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Repetitive passive movement (RPM) enhances reciprocal inhibition. RPM is more effective when performed rapidly and at wide joint angles. However, patients with limited joint range of motion may not receive the most effective RPM. Therefore, having an alternative method for performing RPM in patients who cannot perform actual exercise due to limited joint motion is necessary. This study investigated the effects of RPM on spinal excitability using a visual kinesthetic illusion. Participants included 17 healthy adults (7 women). Measurements were taken before, during, and immediately after the intervention. We established two intervention conditions: the control condition, in which participants focused their attention forward, and the illusion condition, in which participants watched a video about RPM. F-waves from the tibialis anterior and soleus muscles were measured, and F-wave persistence and F/M amplitude ratios were analyzed. Under the illusion condition, compared with the preintervention condition, the F/M amplitude ratio of the tibialis anterior increased by approximately 44% during the intervention (p < 0.05), whereas the F-wave persistence of the soleus decreased by approximately 23% from the immediate start of the intervention (p < 0.05). This study suggests that a visual kinesthetic illusion can increase the spinal excitability of the tibialis anterior, whereas reciprocal inhibition can decrease the spinal excitability of the soleus. [ABSTRACT FROM AUTHOR]

The standard treatment for patients with confirmed Venous Leg Ulcers (VLUs) is compression therapy to improve the function of the calf muscle pump. There is a significant cohort of patients who are unable to tolerate optimal compression therapy or indeed any level of compression therapy. In addition, there is a cohort of patients who can tolerate compression whose ulcers show little or no evidence of healing. There is a need for ways to further improve calf muscle pump function and to improve venous ulcer healing in these patients. Published data were reviewed on the use of Muscle Pump Activation (MPA) using common peroneal nerve neuromuscular electrical stimulation (NMES) to improve calf muscle pump function. There is physiological evidence that MPA can improve calf muscle pump function and venous return in both control subjects and in patients with venous disease. The use of MPA has also been shown to improve venous flow volume and venous flow velocity on ultrasound scanning in patients with venous disease. MPA has been shown to improve microcirculation in the skin using Laser Doppler and laser Doppler Speckle Contrast Imaging, in both normal subjects as well as in patients with venous disease and VLU. A recent randomized controlled trial of MPA plus compression therapy compared with compression therapy alone, found significantly faster rates of healing with the use of MPA in addition to compression therapy. There are indications for the use of MPA as an adjunctive treatment to enhance calf muscle pump function in patients with VLU:who cannot tolerate compression therapywho can only tolerate suboptimal, low‐level compressionwhose ulcer healing remains slow or stalled with optimal compression. [ABSTRACT FROM AUTHOR]

The aim of our study was to compare the effects of two different plyometric training programs (targeting knee extensors or plantar flexors) on jump height and strength of leg muscles. Twenty‐nine male basketball players were assigned to the knee‐flexed (KF), knee‐extended (KE), or control groups. In addition to regular training, the KF group performed plyometric jumps (10 sets of 10 jumps, 3 sessions/week, 4 weeks) from 50 cm boxes with the knee flexed (90°–120°), whereas the KE group performed the jumps from 30 cm boxes with the knee much more extended (130°–170°). Jumping ability was evaluated with squat jumps (SJs), countermovement jumps (CMJs), and drop jumps from 20 cm (DJ20) and 40 cm (DJ40). Knee and ankle muscles were assessed during maximal isokinetic and isometric tests, and EMG activity was recorded from vastus lateralis and medial gastrocnemius. The KF group increased SJ (+10%, d = 0.86) and CMJ (+11%, d = 0.70) but decreased DJ40 height (−7%, d = −0.40). Conversely, the KE group increased DJ20 (+10%, d = 0.74) and DJ40 (+12%, d = 0.77) but decreased SJ height (−4%, d = −0.23). The reactivity index during DJs increased (+10% for DJ20, d = 0.47; +20% for DJ40, d = 0.91) for the KE group but decreased (−10%, d = −0.48) for the KF group during DJ40. Plantar flexor strength increased for the KE group (d = 0.72–1.00) but not for the KF group. Negative transfer across jumps is consistent with the principle of training specificity. Basketball players interested to perform fast rebounds in their training should avoid plyometric jumps with large knee flexions and long contact times. Highlights: Plyometric training specificity: different jump techniques (knee flexed vs. knee extended) elicited specific adaptations in jumping performance. Training with the knees flexed improved squat jump and countermovement jump height, whereas training with the knees extended augmented drop jump height.Negative transfer: the different jump techniques can have a negative influence on jump height and reactivity index. Drop jump height declined after knee‐flexed training, whereas squat jump height decreased after knee‐extended training.Plyometric training exercises should be aligned with sport‐specific movements to optimize performance. Basketball players who perform fast, powerful movements should avoid plyometric jumps with large knee flexions and long contact times. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injuries often occur when an athlete experiences an unexpected disruption, or perturbation, during sports. ACL injury rates may also be influenced by the menstrual cycle. Purpose: To determine whether training adaptations to knee control and muscle activity during a perturbed single-leg squatting (SLS) task depend on menstrual cycle phase in female athletes. Study Design: Controlled laboratory study. Methods: A total of 21 healthy female collegiate athletes (current or former [<3 years]) who competed in 9 different sports performed an SLS task in which they attempted to match their knee position (user signal) to a target signal. The protocol consisted of a 9-condition pretest, 5 sets of 3 training trials, and a 9-condition posttest. One perturbation was delivered in each condition by altering the resistance of the device. Sagittal knee control (absolute error between the target signal and user signal) was assessed using a potentiometer. Muscle activity during perturbed squat cycles was normalized to maximal activation and to corresponding muscle activity during unperturbed squat cycles (%unperturbed) within the same test condition. Athletes performed the protocol during a distinct menstrual cycle phase (early follicular [EF], late follicular [LF], midluteal [ML]). Two-way mixed analysis of variance was used to determine the effects of the menstrual cycle and training on knee control and muscle activity during task performance. Venous blood was collected for hormonal analysis, and a series of health questionnaires and anthropometric measures were also assessed to determine differences among the menstrual cycle groups. Results: After training, athletes demonstrated better knee control during the perturbed squat cycles (lower absolute error, P <.001) and greater soleus feedback responses to the perturbation (%unperturbed, P =.035). Better knee control was demonstrated in the ML phase versus the EF phase during unperturbed and perturbed squat cycles (P <.039 for both). Quadriceps activation was greater in the ML phase compared with the EF and LF phases, both immediately before and after the perturbation (P <.001 for all). Conclusion: Athletes learned to improve knee control during the perturbed performance regardless of menstrual cycle phase. The best knee control and greatest quadriceps activation during the perturbed squatting task was found in the ML phase. Clinical Relevance: These findings may correspond to a lower incidence of ACL injury in the luteal phase and alterations in exercise performance across the menstrual cycle. [ABSTRACT FROM AUTHOR]

Mobilization with movement (MWM) and myofascial release (MFR) are treatment techniques that increase ankle dorsiflexion range of motion (DFROM). Manual lymphatic drainage (MLD) facilitates waste drainage and improves soft tissue tension in peripheral tissues. To date, no studies have investigated how the combination of MLD, MWM, and MFR influences the human body. The purpose of this study is to determine how the combination of MLD, MWM, and MFR affects DFROM and balance ability. We randomly assigned 16 individuals (26 feet) to one of three groups: MWM-MFR (MR), MWM-MLD (MD), or MWM-MFR-MLD (MRD) intervention. To confirm the intervention effect of each group, DFROM was assessed using a modified lunge test, and dynamic balance was measured using a modified star excursion balance test. In the results, differences were found between the MR and MRD groups in PL and mGCM activities in the 1 section (p = 0.008, p = 0.036) and between the MD and MRD groups in mGCM activity in the 4 and 5 sections (p = 0.049, p = 0.004). We suggest that the application of MRD is the most effective intervention for increasing muscle activation of the PL and mGCM during the modified star excursion balance test. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate how additional cognitive tasks (Stroop test and counting backwards task) influence young adults' ability to generate appropriate postural responses while standing on a continuously oscillating platform. Twenty young adults (25.95 ± 2.97 years) stood on a moving platform which was translated in the anterior–posterior direction at three different frequencies (0.10, 0.25 and 0.50 Hz) in three dual‐task conditions (counting backwards task, a Stroop task or no additional cognitive task). Postural muscle onset latencies and tonic activity levels of the leg muscles were measured through surface electromyography; the number of steps taken and cognitive errors made were recorded. Results showed no significant differences in muscle activity between dual and single‐tasking conditions nor between the two dual tasking conditions. Cognitive errors were made in the counting backwards task but not the Stroop task. A frequency effect was identified with participants showing greater tonic activity in rectus femoris (p = 0.012), gastrocnemius medialis (p = 0.016) and bicep femoris (p = 0.043) at 0.5 Hz, as well as earlier muscle activation in tibialis anterior, gastrocnemius medialis and bicep femoris (p < 0.001) at 0.50 Hz. Transition and steady state muscle onset latencies were only significantly different for gastrocnemius medialis at 0.25 Hz (p = 0.001). Dual tasking did not seem to influence anticipatory postural adjustments in young adults; however, perturbation intensities did. The differences observed in the number of cognitive errors made could be indicative of the regional cortical activations and overlapping demand for resources interfering with balance control, though cortical activation was not recorded. Future research should include detailed cognitive behavior, including cortical activations and task reaction times to better understand the allocation of attentional resources during perturbed balance dual tasking. Highlights: Directionally specific muscle onset latencies in the tibialis anterior, gastrocnemius medialis and bicep femoris were triggered sooner at 0.50 Hz than in the other lower frequencies.Postural responses were largely unchanged between single and dual tasking, suggesting that for young adults, dual‐tasking appears to have no more strength to alter postural control responses than altered support surface stability alone.Only the counting backwards dual‐task condition elicited cognitive errors, suggesting a potential overlapping demand for resource allocation between tasks, though this will need to be confirmed in future work with observation of cortical activation (e.g., through EEG or fNIRS) [ABSTRACT FROM AUTHOR]

Purpose: This study investigates the effects of exercises on sand on the frequency content of the lower limb muscles in individuals with anterior cruciate ligament reconstruction and pronated feet during walking. Methods: This was a semi-experimental and laboratory-type study. The study samples included 28 male students with pronated feet and anterior... [ABSTRACT FROM AUTHOR]

Background: Calcaneus distress is a frequent moan in the trotter and talus, and plantar fasciosis, which accounts for 11-15% of adult patients' symptoms of the foot need medical attention. One in ten people are predicted to get PF at some point in their lives. It is further prevalent in mid-life fat women and adolescent athletes. The desire of this project is to evaluate the success of calf stretching by theraband among plantar fasciitis patients. Purpose: To determine the effects of calf stretching using theraband on managing pain among plantar fasciitis patients Materials and Methods: Fifty eight people were covered for addition and prohibition. They were splitted into two groups: passive calf stretching group (29) and self-calf stretching group (29). The pre and post-test values were measured by pain catastrophizing scale. Group-A received passive calf stretching using theraband and group-B received self-calf stretching. Both programs were given for 2 weeks, weekly 5 days. Result: Using pain catastrophizing scale, Group A's (Passive calf stretching group) post-test mean was 27.38 and whereas group B's (Self calf stretching) was 32.24. This demonstrates that group-A has decreased pain catastrophizing score less than group-B. And this suggests that group A showed considerably finer than group B. Conclusion: Passive calf stretching using theraband by group-A was found to be more effective than self-calf stretching of group-B.. [ABSTRACT FROM AUTHOR]

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Background: Muscle wasting is a common phenomenon in oncology and seems to be attenuated by exercise training. The aim of this study is to determine the degree of aggressiveness of cancer-induced muscle wasting in two different phenotypic muscles. It will also determine whether exercise training can attenuate this muscle dysfunction. Methods: Fifty Sprague Dawley rats were randomly assigned to four experimental groups: two breast cancer model groups (sedentary and exercise) and two control groups (sedentary and exercise). Breast cancer was induced by 1-methyl-1-nitrosoureia (MNU). After 35 weeks of endurance training, animals were sacrificed, and gastrocnemius and soleus muscles harvested for morphometric analysis. Results: In sedentary tumor-bearing animals, a significant reduction in cross-sectional area was found in both muscles (p < 0.05). Interstitial fibrosis was significantly higher in the gastrocnemius muscle of the sedentary tumor-bearing animals (p < 0.05), but not in the soleus muscle. In the gastrocnemius of sedentary tumor-bearing animals, a shift from large to small fibers was observed. This cancer-related muscle dysfunction was prevented by long-term exercise training. Conclusions: In sedentary animals with tumors, the gastrocnemius muscle showed a very pronounced reduction in cross-sectional area and a marked degree of interstitial fibrosis. There was no difference in collagen deposition between tumor groups, and the soleus muscle showed a less pronounced but significant reduction in cross-sectional area. These contrasting results confirm that cancer-induced muscle wasting can affect specific types of fibers and specific muscles, namely fast glycolytic muscles, and that exercise training can be used to improve it. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the neural changes that differentiate Parkinson's disease patients with freezing of gait and age-matched controls, using ambulatory electroencephalography event-related features. Compared to controls, definite freezers exhibited significantly less alpha desynchronization at the motor cortex about 300 ms before and after the start of overground walking and decreased low-beta desynchronization about 300 ms before and about 300 and 700 ms after walking onset. The late slope of motor potentials also differed in the sensory and motor areas between groups of controls, definite, and probable freezers. This difference was found both in preparation and during the execution of normal walking. The average frontal peak of motor potential was also found to be largely reduced in the definite freezers compared with the probable freezers and controls. These findings provide valuable insights into the underlying structures that are affected in patients with freezing of gait, which could be used to tailor drug development and personalize drug care for disease subtypes. In addition, the study's findings can help in the evaluation and validation of nonpharmacological therapies for patients with Parkinson's disease. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the acute effects of back squat exercise with or without elastic band on counter-movement jump performance. Thirteen collegiate male basketball players (age: 20.5 ± 0.9 years; height: 188.5 ± 8.5 cm; body mass: 82.8 ± 12.9 kg) completed 5 familiarization and 4 experimental sessions separated by at least 48 hours. In the experimental sessions, the order of the conditions was randomized so that the participants performed 1 set of 3 repetitions of barbell back squat at 85% of their one-repetition maximum (1-RM), 1 set of 3 repetitions of back squat at 85% 1-RM with 20% variable resistance training (VRT), 30%VRT, or 40%VRT of the total load coming from the elastic band. Countermovement jump performance was assessed before (baseline), 30 seconds, 3 minutes, 6 minutes, and 9 minutes following each condition. Jump height, rate of force development, peak power, and vastus lateralis, vastus medialis, and medial gastrocnemius electromyography data were collected. Compared with the baseline, 30%VRT significantly improved jump height at 3 minutes post-exercise by 1.3 cm (P < 0.001) and 6 minutes post-exercise by 1.2 cm (P = 0.005); 40%VRT significantly improved jump height from 30 seconds up to the 9th minute (1.2 to 1.9 cm, P ≤ 0.036). The superior jump height was also accompanied by improved kinetic and electromyography data. No significant changes were observed in the barbell back squat and 20%VRT conditions. In conclusion, back squat at 85% 1-RM with 40% elastic band resistance led to superior vertical jump performance with an optimal time window of 3 minutes. [ABSTRACT FROM AUTHOR]

Background The Y-Balance Test (YBT), especially the posteromedial (PM) reach direction (PM-YBT), is able to identify dynamic postural control deficits in those who have ankle instability. However, there still exists a need to understand how sensorimotor function at the ankle explains the performance during the PM-YBT. Hypothesis/Purpose The purpose of this study was to determine whether the ability to accurately control eccentric ankle torque explained PM-YBT performance. It was hypothesized that eccentric dorsiflexion/plantarflexion torque control would be positively related to the maximum reach distance (MRD) of PM-YBT. Study Design Cross-sectional study Methods Twelve healthy subjects performed the PM-YBT, maximum voluntary isometric contractions (MVIC) for both dorsiflexion and plantarflexion muscle strength, and then the torque control testing of the ankle. The torque control testing provided a target torque level on a screen in front of the subject and passive rotations of the ankle joint in the sagittal plane at 10 deg/sec between plantarflexion to dorsiflexion. Subjects were then instructed to eccentrically contract the dorsiflexors and plantar flexors to generate torque while the ankle joint rotated. The accuracy of torque control during eccentric dorsiflexion and plantarflexion by calculating absolute errors, the area between the target torque and the produced torque were evaluated. Tibialis anterior and soleus muscle activities were simultaneously recorded during testing. A step-wise linear regression model was used to determine the best model predicted the MRD of the PM-YBT (PM-MRD). Results A step-wise linear regression developed a model explaining only eccentric dorsiflexion torque control predicted higher PM-MRD score (R² = 44%, F1,10 = 7.94, β = -0.67, p = 0.02). Conclusion The accuracy of torque control during eccentric dorsiflexion predicts better performance in the PM-YBT. [ABSTRACT FROM AUTHOR]

Purpose: A key determinant of long jump performance is the ability to increase the vertical velocity of the center of mass (COM) while minimizing the loss in forward velocity (running speed) during the take-off phase, but exactly how this occurs is not fully understood. We combined a three-dimensional musculoskeletal model of the body with dynamic optimization theory to simulate the biomechanics of the long jump take-off and determine the contributions of the individual leg muscles to jump performance. Methods: The body was modeled as a 29-degree-of-freedom skeleton actuated by a combination of muscles and net joint torques. A dynamic optimization problem was solved to reproduce full-body motion and ground-force data recorded from experienced subelite jumpers. The optimization solution then was analyzed to determine each muscle's contribution to the ground-force impulse and hence the change in velocity of the COM during the take-off phase. Results: The hip, knee, and ankle extensors dominated the change in velocity of the COM during take-off. Vasti (VAS) generated the highest support impulse and contributed one-third (33%) of the increase in vertical COM velocity generated by all the muscles. Soleus (SOL) and gluteus maximus (GMAX) also developed substantial support impulses and contributed 24% and 16% of the increase in vertical COM velocity, respectively. VAS also generated the highest braking impulse and contributed approximately one-half (55%) of the loss in forward COM velocity generated by all the muscles, whereas SOL and GMAX made much smaller contributions (12% and 7%, respectively). Conclusions: VAS, SOL, and GMAX contributed nearly three-quarters (73%) of the increase in vertical COM velocity at take-off, suggesting that these muscles ought to be prioritized in strength training programs aimed at improving long jump performance. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the effects of specialized Kyokushin karate exercises on the activity of leg muscles and the height of the medial longitudinal arch in adolescent girls with foot pronation. Methods: This study recruited twenty-four adolescent girls with foot pronation who voluntarily agreed to participate and were randomly assigned to either a training group (n=12) or control group (n=12). The training program consisted of eight weeks of specialized Kyokushin karate exercises. The fibularis longus, tibialis anterior, and lateral gastrocnemius muscles activity was measured during single-leg landing using surface electromyography. The medial longitudinal arch height was measured using the navicular drop test. All statistical analyses, including independent and paired t-tests, were conducted using SPSS software, version 26 at a significance level of 0.05. Results: The results showed that following eight weeks of specialized Kyokushin karate exercises, there was a significant increase in the activity levels of the tibialis anterior (P=0.005) and lateral gastrocnemius (P=0.04) muscles in the training group compared to the control group. However, there was no significant change in the activity of the fibularis longus muscle in the training group compared to the control group (P>0.05). Within the training group, there was a significant increase in the activity of all three measured muscles (fibularis longus, P=0.009; tibialis anterior, P=0.008; and lateral gastrocnemius, P=0.008) from post-test to pre-test (P<0.05). Additionally, the study found that the amount of navicular drop in the training group was significantly reduced compared to the control group (P=0.04) after eight weeks of training Conclusion: This study demonstrated that eight weeks of specialized Kyokushin karate exercises resulted in a significant increase in the activity levels of the tibialis anterior and lateral gastrocnemius muscles in adolescent girls with foot pronation. These exercises also improved the height of the medial longitudinal arch, indicating a potential solution for correcting flat feet. Therefore, we recommend Kyokushin karate exercises to improve muscle activity and arch height in adolescent girls with foot pronation. [ABSTRACT FROM AUTHOR]

Introduction: Flexibility is an important physiological component of physical fitness. The length of the muscle tissue is thought to play an important role in the effectiveness and efficacy of human movement. Calf is one of the commonest muscle prone to tightness. Most of the forefoot and ankle problems arise due to gastrocnemius and soleus tightness and contractures. To manage such a condition, stretching of the calf muscles are commonly prescribed to increase available dorsiflexion of the ankle joint. Though there are several effective physiotherapeutic exercises available to resolve this problem, but it's still in dilemma about the immediate effects. Muscle Energy Technique (MET) and Static Stretching (SS) are the techniques which can efficiently improve the flexibility of muscles and also very scarce literature is present on comparing the effect of these techniques for increasing ankle dorsiflexion for improving calf tightness. So, this study aimed to evaluate and compare the immediate effect of Muscle Energy Technique and Static Stretching on calf flexibility in females. Methodology: An experimental study in which 30 female subjects aged between 18 to 25 years were divided into two groups.GroupA (n= 15) and Group B (n=15) were given MET and Static Stretching (SS) respectively. Ankle Dorsiflexion ROM was assessed pre- intervention and post- intervention. The data collected were analyzed by SPSS (version 26). Result and Conclusion: Group A (MET) and Group B (SS) were given suitable intervention for calf muscle tightness, and bothgroups showed that the mean ROM during post-test was higher than pre-test. After the comparison of both groups, no significant difference was seen in the mean scores (p≥ 0.05). Equal number of repetitions of both techniques were given, however, still MET showed slightly greater effect. Therefore, the study concluded that fewer repetitions of MET could have greater or equal effect as Static Stretching. Further studies with large sample size and follow up are recommended. [ABSTRACT FROM AUTHOR]

Purpose: Neuroimaging and electrodiagnostic studies are used to evaluate the changes in the spinal cord after trauma, both for clinical and research purposes. The aim of the present study was to find a correlation between the MRI and electrodiagnostic testing for acute traumatic spinal cord injury (SCI) over different points in time. Methods: Thirty-five patients with acute SCI presenting within 48 h of injury and completing a minimum of 6 months of regular follow-up comprised the study population. Patients were examined clinically for neurological involvement as per international guidelines. Magnetic resonance imaging (MRI) spine and electrodiagnostic testing of both lower limbs [two motor (tibial and peroneal) and one sensory (sural) nerve] and five muscles (Iliopsoas, Vastus medialis, Tibialis anterior, Gastrocnemius, and Extensor hallucis longus (EHL)] were done at admission, 3 and 6 months. Results: Quantitative MRI parameters [maximum spinal cord compression (MSCC), maximum canal compromise (MCC), and lesion length (LL)] showed a significant correlation to motor nerve conduction velocity and sensory nerve conduction velocity at all points in time. Electromyography of tested muscles at admission showed a significant correlation (Spearman's correlation test) with MRI quantitative parameters (-0.818 to -0.510); stenosis (-0.564 to -0.347) except right EHL for peak to peak amplitude; and disk herniation (-0.427 to -0.339) except tibialis anterior for recruitment of motor unit potential (MUP) and iliopsoas, right gastrocnemius, and EHL for peak to peak amplitude. This correlation remained significant even at 3 and 6 months post-acute SCI. Conclusion: The quantitative MRI parameters, along with a few of the qualitative parameters, show a significant correlation with electrodiagnostic features at different points in acute traumatic SCI. [ABSTRACT FROM AUTHOR]

Introduction: The effect of cadence in eccentric (ECC) cycling on physiological and perceptual responses is, to date, poorly understood. This study aimed to evaluate the effect of cadence during ECC cycling on muscular activation (EMG), oxygen consumption (V̇O2), and perceived effort (PE) for two different levels of power output. Methods: Seventeen participants completed four sessions 1 wk apart: 1) determination of the maximal concentric peak power output (PPO) and familiarization with ECC cycling at five cadences (30, 45, 60, 75, and 90 rpm); 2) second familiarization with ECC cycling; 3) and 4) ECC cycling exercise consisting of 5 min at the five different cadences at either 40% or 60% PPO. PE was reported, and V̇O2 and EMG of seven muscles were calculated over the exercise's last minute. Results: PE, V̇O2, and global lower limb muscles activation (EMGALL) showed an effect of cadence (P < 0.001) and followed a curvilinear function. Both low and high cadences increased PE and V̇O2 responses compared with intermediate cadences. Although muscle activation of vastus lateralis follows a U-shaped curve with cadence, it was greater at low cadence for rectus femoris and biceps femoris, greater at high cadence for tibialis anterior and gastrocnemius medialis, and was not altered for soleus. The estimated optimal cadence was greater (all P < 0.01) for V̇O2 (64.5 ± 7.9 rpm) than PE (61.7 ± 9.4 rpm) and EMGALL (55.9 ± 9.3 rpm), but power output had no effect on the optimal cadences. Conclusions: The physiological and perceptual responses to changes in cadence during ECC cycling followed a U-shaped curve with an optimal cadence depending on the parameter considered. [ABSTRACT FROM AUTHOR]

Purpose: Heat acclimation (HA) is recommended before competing in hot and humid conditions. HA has also been recently suggested to increase muscle strength, but its effects on human's muscle and tendon mechanical properties are not yet fully understood. This study investigated the effect of active HA on gastrocnemius medialis (GM) muscle–tendon properties. Methods: Thirty recreationally active participants performed 13 low-intensity cycling sessions, distributed over a 17-d period in hot (HA = ~38°C, ~58% relative humidity; n = 15) or in temperate environment (CON = ~23°C, ~35% relative humidity; n = 15). Mechanical data and high-frame rate ultrasound images were collected during electrically evoked and voluntary contractions pre- and postintervention. Shear modulus was measured at rest in GM, and vertical jump performance was assessed. Results: Core temperature decreased from the first to the last session in HA (−0.4°C ± 0.3°C; P = 0.015), while sweat rate increased (+0.4 ± 0.3 L·h−1; P = 0.010), suggesting effective HA, whereas no changes were observed in CON (both P ≥ 0.877). Heart rate was higher in HA versus CON and decreased throughout intervention in groups (both P ≤ 0.008), without an interaction effect (P = 0.733). Muscle–tendon unit properties (i.e., maximal and explosive isometric torque production, contractile properties, voluntary activation, joint and fascicular force–velocity relationship, passive muscle, and active tendon stiffness) and vertical jump performance did not show training (P ≥ 0.067) or group–training interaction (P ≥ 0.232) effects. Conclusions: Effective active HA does not alter muscle–tendon properties. Preparing hot and humid conditions with active HA can be envisaged in all sporting disciplines without the risk of impairing muscle performance. [ABSTRACT FROM AUTHOR]

Purpose: Voluntary activation (VA) determined by interpolation-twitch technique could be affected by the characteristics of the in-series elastic components. To overcome this possible bias, a novel approach based on the mechanomyographic (MMG) signal to detect voluntary activation (VAMMG) has been proposed. We examined the changes in VA and VAMMG after passive stretching to check the influence of neural and mechanical factors in the force output. Methods: Twenty-six healthy men underwent VA assessment using the interpolated-twitch technique before and after unilateral passive stretching of the plantarflexors (five 45-s on + 15-s off). In addition to the force signal, the MMG signal was detected on gastrocnemius medialis, gastrocnemius lateralis, and soleus. From the force and MMG signal analysis, VA and VAMMG were calculated in the stretched and contralateral nonstretched limbs. Joint passive stiffness was also defined. Results: In the stretched limb, passive stretching increased dorsiflexion range (mean ± SD = +18% ± 10%, P < 0.001, ES = 1.54) but reduced joint passive stiffness (−22% ± 8%, P < 0.001, ES = −1.75), maximum voluntary contraction (−15% ± 7%, P < 0.001, ES = −0.87), VA (−7% ± 3%, P < 0.001, ES = −2.32), and VAMMG (~−5% ± 2%, P < 0.001, ES = −1.26/−1.14). In the contralateral nonstretched limb, passive stretching increased dorsiflexion range (+10% ± 6%, P < 0.001, ES = 0.80) but reduced joint passive stiffness (−3% ± 2%, P = 0.041, ES = −0.27), maximum voluntary contraction (−4% ± 3%, P = 0.035, ES = −0.24), VA (−4% ± 2%, P < 0.001, ES = −1.77), and VAMMG (~− 2% ± 1%, P < 0.05, ES = −0.54/−0.46). The stretch-induced changes in VA correlated with VAMMG (R ranging from 0.447 to 0.583 considering all muscles) and with joint passive stiffness (stretched limb: R = 0.503; contralateral nonstretched limb: R = 0.530). Conclusions: VA output is overall influenced by both neural and mechanical factors, not distinguishable using the interpolated-twitch technique. VAMMG is a complementary index to assess the changes in VA not influenced by mechanical factors and to examine synergistic muscles. [ABSTRACT FROM AUTHOR]

The present study aims to determine the test-retest reliability of the input signal (INPUT) of foot impact and soft tissue vibration (STV) of the lower limb muscles during treadmill running. Twenty-six recreational runners participated in three running trials at constant velocity (10 km/h) within two days. The INPUT and STV of gastrocnemius medialis (GAS) and vastus lateralis (VL) were extracted from 100 steps measured by three triaxial accelerometers. The Intraclass Correlation Coefficient (ICC) was calculated to determine the Intra-trial and Inter-day reliability of the different variables. Intra-trial reliability results indicated that most of the INPUT and GAS STV parameters, except for damping coefficient and setting time, have good to excellent reliability (0.75 < ICC < 0.9) from the beginning of the run (10 steps) to the end. In contrast, only 4 VL STV parameters showed good reliability. Furthermore, inter-trial reliability measured on day one showed that the number of reliable parameters reduced, especially for VL STV, and more steps were required (20 < steps < 80) to achieve good reliability. Inter-day reliability results showed that only one VL STV parameter reached good reliability. Therefore, the present results show that the measurement of the foot impact and the calf muscle vibrations present a good to excellent reliability measured on a single trial and two trials carried out on the same day. The reliability of these parameters remains good when comparing two days of experimentation. We recommend measuring impact and STV parameters during treadmill running in the same session. [ABSTRACT FROM AUTHOR]

Studies have reported that a stiff triceps surae muscle and tendonaponeurosis and also a more compliant quadriceps muscle and tendon-aponeurosis, are related to lower oxygen cost during running. However, to date, no study has investigated in a single experiment how oxygen cost during running is related to the stiffness of the free tendons (Achilles tendon, patellar tendon) and all the superficial muscles of two major muscle groups for running (i.e., quadriceps, triceps surae). Thus, 17 male trained runners/triathletes participated in this study and visited the laboratory on three occasions. On the first day, the participants were familiarized with the tests. On the second day, the passive compression stiffness of the triceps surae muscle (i.e., gastrocnemii), Achilles tendon, quadriceps muscle (i.e., vastii, rectus femoris), and patellar tendon was non-invasively measured using a digital palpation device (MyotonPRO). In addition, an incremental test was applied to test the VO2max of the participants. Thereafter, in the third visit, after at least 48-h of rest, participants performed a 15-min run on the treadmill with a speed reflecting a velocity of 70% VO2max, to assess oxygen costs during running. The Spearman correlation showed a significant negative correlation between passive Achilles tendon compression stiffness and running oxygen consumption, with a large effect size (rρ = -0.52; CI (95%) -0.81 to -0.33; P = 0.03). Moreover, no further significant relationship between oxygen cost during running and the passive compression stiffness of the quadriceps muscle and patellar tendon, as well as the triceps surae muscle, was detected. The significant correlation indicates that a stiffer passive Achilles tendon can lead to a lower oxygen cost during running. Future studies will have to test the causality of this relationship with training methods such as strength training that are able to increase the Achilles tendon stiffness. [ABSTRACT FROM AUTHOR]

Although neuromuscular deficits in people with chronic ankle instability (CAI) have been identified, previous researchers have mostly investigated the activation of multiple muscles in isolation. Investigating muscle synergies in people with CAI would provide information about the coordination and control of neuromuscular activation strategies and could supply important information for understanding and rehabilitating neuromuscular deficits in this population. To assess and compare muscle synergies using nonnegative matrix factorization in people with CAI and healthy control individuals as they performed different landing-cutting tasks. Cross-sectional study. Laboratory. A total of 11 people with CAI (5 men, 6 women; age = 22 ± 3 years, height = 1.68 ± 0.11 m, mass = 69.0 ± 19.1 kg) and 11 people without CAI serving as a healthy control group (5 men, 6 women; age = 23 ± 4 years, height = 1.74 ± 0.11 m, mass = 66.8 ± 15.5 kg) participated. Muscle synergies were extracted from electromyography of the lateral gastrocnemius, medial gastrocnemius, fibularis longus, soleus, and tibialis anterior (TA) muscles during anticipated and unanticipated landing-cutting tasks. The number of synergies, activation coefficients, and muscle-specific weighting coefficients were compared between groups and across tasks. The number of muscle synergies was the same for each group and task. The CAI group exhibited greater TA weighting coefficients in synergy 1 than the control group (P =.02). In addition, both groups demonstrated greater fibularis longus (P =.03) weighting coefficients in synergy 2 during the unanticipated landing-cutting task than the anticipated landing-cutting task. These results suggest that, although both groups used neuromuscular control strategies of similar complexity or dimensionality to perform the landing-cutting tasks, the CAI group displayed different muscle-specific weightings characterized by greater emphasis on TA function in synergy 1, which may reflect an effort to increase joint stability to compensate for ankle instability. [ABSTRACT FROM AUTHOR]

(1) Background: Forward step-up (FSU) simulates the stance phase in stair ascension. With the benefits of physical properties of water, aquatic FSU exercise may be more suitable for patients with lower limb weakness or pain. The purpose of this study is to investigate the effect of progressive steps per min on the surface electromyography (sEMG) of gluteus maximus (GM), biceps femoris (BF), rectus femoris (RF), and gastrocnemius (GA), when performing FSU exercise with different steps per min in water and on land. (2) Methods: Participants (N = 20) were instructed to perform FSU exercises at different steps per min (35, 60, and 95 bpm) in water and on land. The sEMG of the tested muscles were collected. The percentage maximum voluntary isometric contraction (%MVIC) of GM, RF, GA and BF at different environments and steps per min was compared. (3) Result: There was a statistically significant difference of %MVIC of RF at all steps per min comparisons regardless of the movement phases and environments (p < 0.01, except for descending phases of 35 bpm vs. 60 bpm). All tested muscles showed a statistically significant lower muscle activation in water (p < 0.05) (4) Conclusion: This study found that the %MVIC of the tested muscle in both investigated environments increase as steps per minute increases. It is also found that the movement pattern of FSU exercise activates RF the most among all the tested muscles. Muscle activation of all tested muscles is also found to be smaller in water due to buoyancy property of water. Aquatic FSU exercise might be applicable to patients with lower limb weakness or knee osteoarthritis to improve their lower limb strength. [ABSTRACT FROM AUTHOR]

This study examined the effects of gaze fixation and different kinds of smooth-pursuit eye movements on the trunk and lower extremity muscle activities and center of pressure. Methods: Twenty-four subjects were selected for the study. The activity of trunk and lower limb muscles (tibialis anterior, lateral gastrocnemius, medial gastrocnemius, vastus midialis obliques, vastus lateralis, biceps femoris, rectus abdominis, and erector spinae) and the COP (center of pressure) (surface area ellipse, length, and average speed) were measured to observe the effects of gaze fixation and different kinds of smooth-pursuit eye movements on the center of pressure and muscle activities during one leg standing. Before the experiment, a Gaze point GP3 HD Eye Tracker (Gazept, Vancouver, BC, Canada) was used to train eye movement so that the subjects would be familiar with smooth eye movement. Repeated each exercise 3 times at random. In order to avoid the sequence deviation caused by fatigue, the movement sequence is randomly selected. Result: The center of pressure and muscle activities were increased significantly when the smooth-pursuit eye movement with one leg standing compared with gaze fixation with one leg standing. In smooth-pursuit eye movements, the changes in the center of pressure and muscle activities were increased significantly with eye and head movement. When the head and eyes moved in opposite directions, the center of pressure and muscle activities were increased more than with any other exercises. Conclusion: Smooth-pursuit eye movement with one leg movement affects balance. In particular, in the smooth-pursuit eye movement with one leg standing, there were higher requirements for balance when the eyes and head move in the opposite direction. Therefore, this movement can be recommended to people who need to enhance their balance ability. [ABSTRACT FROM AUTHOR]

To investigate how plyometric exercise (PLYO-Ex) affects mechanics and morphometrics of the plantar flexor musculotendinous unit in children with unilateral cerebral palsy, 38 participants (aged 10–16 years) were allocated at random to either the PLYO-Ex group (n = 19; received 24 sessions of plyometric muscle loading, conducted 2 times a week for 3 months in succession) or the control group (n = 19; underwent traditional physical therapy for the same frequency and duration). Measurements were taken pre- and post-intervention. Standard ultrasound imaging was applied to evaluate morphometrics of the gastrocnemius muscle and Achilles tendon unit and an isokinetic dynamometer was used to evaluate maximum voluntary isometric plantar flexors contraction (IVCmax). With controlling for pre-treatment values, significant post-treatment changes favoring the PLYO-Ex group were observed for morphological (tendon (p = 0.003, η2p = 0.23) length; belly length (p = 0.001, η2p = 0.27); tendon thickness (p = 0.035, η2p = 0.35); muscle thickness (p = 0.013, η2p = 0.17); fascicle length (p = 0.009, η2p = 0.18); pennation angle (p = 0.015, η2p = 0.16)) and mechanical and material properties (IVCmax (p = 0.009, η2p = 0.18); tendon's elongation (p = 0.012, η2p = 0.17), stiffness (p = 0.027, η2p = 0.13); stress (p = 0.006, η2p = 0.20); strain (p = 0.004, η2p = 0.21)). In conclusion, plyometric exercise induces significant adaptations within the musculotendinous unit of the plantar flexors in children with unilateral cerebral palsy. These adaptations could improve muscular efficiency and consequently optimize physical/functional performance. [ABSTRACT FROM AUTHOR]

Background: Sprinter is a person who runs very fast over a short distance in a race. In this study we determine the effect of Instrument Assisted Soft Tissue Manipulation (IASTM) vs THERAGUN separately on triceps surae muscle to check the Active Range of Motion and Functional Movement in sprinters of age group 18- 25 years. Methods: Study design: Experimental study (pre-test and post-test design). Sampling Technique: The subjects were selected by Random Sampling. Source of Data: Universities of Patiala & Ludhiana Districts. Conclusion: The study examined the effect of IASTM Active Range of Motion & functional movement. [ABSTRACT FROM AUTHOR]

BACKGROUND: By examining whether age and speed each differently affect beta coherence during walking, we can extend the limited evidence on age-related impairment in the neural control of walking. AIM: We determined the effects of age and walking speed on intermuscular beta coherence between lower extremity muscle pairs and the association between stride characteristics and intermuscular beta coherence in these muscle pairs. METHOD: Older (n=12) and younger (n=14) individuals walked on a treadmill at fixed (1.2 m/s) and fast (~1.3x preferred) speeds for 3min. For 100 dominant leg strides, we measured length, width, stance, swing time, cadence and intermuscular beta coherence (15-35Hz) for the synergistic thigh (biceps femoris (BF)-semitendinosus, rectus femoris (RF)-vastus lateralis (VL)) and ankle (Gastrocnemius lateralis (GL)-soleus (SL), Tibialis anterior (TA)- peroneus longus (PL)) and the antagonistic (RF-BF and TA-GL) muscle pairs in swing and stance phases. RESULTS: Comparing fast vs. fixed speed, participants walked with longer strides (21%), faster cadence (12%), and greater coefficient of variation (CV) of stride length (14%), narrower stride width (-20%), and shorter stance (- 5%) and swing times (-14%) and with stronger TA-GL beta coherence in early stance (69%, all p<0.01). Older vs. younger individuals walked with slower fast gait speed (~9%), higher CV of stride length (21%), weaker GL-SL (- 47%) and TA-PL (-60%) beta coherences during the late swing and early stance phase, respectively (all p<0.01). No Group*Condition interactions occurred. CONCLUSION: While old age seems to affect synergistic ankle but not thigh muscle beta coherence, based on a lack of speed effect on coherence and a lack of association between spatiotemporal gait variables and ankle muscle beta coherence, variables other than intermuscular beta coherence most likely underlie age-differences in the neural control of walking speed. [ABSTRACT FROM AUTHOR]

BACKGROUND: Stretching exercises increase the joint range of motion (ROM) and depend on the skeletal tissues' exposition-time to stretch. However, it is unclear how a long stretching time affects the muscle-tendon unit's passive mechanical properties. AIM: This study aimed to analyze changes in the triceps surae muscle-tendon unit’s passive mechanical properties before and after a 10-minute passive stretching protocol. METHOD: Thirty healthy participants (26.57 ± 3.82 years old) were allocated into a control group (n=15), who did not perform any intervention, and to an experimental group (n=15), who performed one bout of a 10-minute ankle plantar flexor passive static stretching. Ankle ROM, plantar flexor passive torque, and myotendinous junction displacement were evaluated pre-intervention, immediately after, and 15, 30, 45, and 60 minutes after the end of the intervention. The stiffnesses of the muscle-tendon unit, muscle, and tendon were calculated for all moments. A generalized estimating equation test was performed to compare groups and moments. RESULTS: The experimental group increased the ROM (p<0.001) from pre- to post-intervention and remained augmented up to 60 minutes. The myotendinous junction displacement decreased at post-30 and post-45 moments compared to pre-intervention. Muscular stiffness increased immediately after stretching and post-45 and post-60 minutes. Passive torque and musculotendinous unit stiffness decreased over time, with trivial, small, and moderate effect sizes, respectively. CONCLUSION: Passive static stretching (10 min) generates an acute ROM increase associated with muscletendon unit passive mechanical properties reduction, which lasts up to one-hour post-intervention. [ABSTRACT FROM AUTHOR]

Introduction: During exercise, angiogenesis occurs in active skeletal muscle; however, little is known about potential mechanisms for improving this adaptation. This study aimed to investigate a period of interval training on chemokine gene expression and its effect on vascular endothelial growth factors in male adult rats. Material & Methods: In this study, 24 rats were divided into three groups (n=8 in each): high-intensity training (HIT), low-intensity training (LIT), and control groups. HIT and LIT groups were trained for eight weeks (five days per week). The exercise program in the HIT group consisted of running on a treadmill for 8 min with 85-90% VO2max intensity and 2 min with 50-60% VO2max intensity. The LIT group exercise program consisted of running on a treadmill for 8 min with 55-60% VO2max intensity and 2 min with 45- 50% VO2max intensity. The control group had no training. The expression of chemokine and vascular endothelial growth factor genes was measured in soleus muscle. The data were analyzed using one-way ANOVA and Tukey post hoc test. Statistical differences were considered significant at P<0.05. (Ethic code: 141/370299) Findings: The results of this study, showed that the expression levels of chemokine and vascular endothelial growth factor gene in the HIT group were significantly higher than that in the control group (P=0.01, P=0.04), while the levels of chemokine and vascular endothelial growth factor in the LIT group were not significantly different from those in the control group (P=0.2, P=0.1). Discussion & Conclusion: According to the results of the present study, it seems that high-intensity exercises can be more effective than low-intensity exercises in increasing angiogenesis caused by the increase of chemokine that in turn depends on vascular endothelial growth factor levels. [ABSTRACT FROM AUTHOR]

The occurrence and mechanisms underlying non-local or crossover muscle fatigue is an ongoing issue. This study aimed to investigate crossover fatigue of the plantar flexor muscles. Sixteen recreationally active males (n = 6) and females (n = 10) visited the laboratory for four sessions and performed a single 5-s pre-test maximal voluntary isometric contraction (MVIC) with each plantar flexors muscle. Thereafter, the fatigue intervention involved two 100-s MVICs (60-s recovery) with their dominant plantar flexors or rested for 260-s (control). Subsequently, in two separate sessions, Hoffman reflexes (H-reflex) were evoked in the non-dominant, non-exercised, leg before and following the dominant leg fatigue or control intervention (Fatigue-Reflex and Control-Reflex conditions). MVIC forces and volitional (V)-waves were monitored in the non-dominant leg in the other two sessions (Fatigue-MVIC and Control-MVIC) before and after the intervention (fatigue or control) as well as during 12 repeated MVICs and immediately thereafter. Despite the force reduction in the dominant leg (42.4%, p = 0.002), no crossover force deficit with single (F(1,9) = 0.02, p = 0.88, pη² = 0.003) or repeated (F(1,9) = 0.006, p = 0.93, pη² = 0.001) MVIC testing were observed. The H-reflex did not change after the fatigue (F(1,7) = 0.51; p = 0.49; pη² = 0.06) or repeated MVICs (F(1,8) = 0.27; p = 0.61; pη² = 0.03). There were also no crossover effects of fatigue on the V-wave with single (F(1,8) = 3.71, p = 0.09, pη² = 0.31) or repeated MVICs (F(1,6) = 1.45, p = 0.27, pη² = 0.19). Crossover fatigue was not evident with the plantar flexors nor any significant changes in H-reflex and V-waves in the soleus muscle. This finding suggests that crossover fatigue may not necessarily occur in slow-twitch predominant muscle groups. [ABSTRACT FROM AUTHOR]

Objective Plantar fasciitis is the most common cause of heel pain. The night splints are used to prevent nocturnal contractures happening in the calf muscles and plantar fascia. The objective of this study was to investigate the effects of using a tension night splint for calf and plantar fascia on the range of motion of foot and ankle complex, pain severity, and quality of life. Materials & Methods 30 people (27 female) with plantar fasciitis volunteered in a parallel-group clinical study. Participants were allocated to three study groups: a tension calf splint, a tension plantar fascia splint, and a control group (heel pad). The study outcomes were the range of motion of foot and ankle complex, pain severity, and quality of life measured with a goniometer, visual analog scale, and 36-Item Short Form Survey (SF-36) questionnaire, respectively. The post-session was four weeks after participants received their interventions. The analysis of covariance statistical test was used to analyze the within and between-group differences. Results The analysis of covariance test showed statistically significant differences for pain (F=9.35, P=0.001, η2=0.44) and extension of the first metatarsophalangeal (F=4.76, P=0.017, η2=0.27). There was no statistically significant difference in the quality of life and the ankle dorsiflexion range between groups (P>0.05). The Bonferroni post-hoc showed a significant reduction of the reported pain post-session in all study groups (P<0.05). The calf tension splint caused a greater extension of the first metatarsophalangeal post-session (P=0.02). Conclusion All three orthoses used in this study significantly reduced pain in people with plantar fasciitis. The results also suggest that a tension calf splint has greater effectiveness in improving pain severity and soft tissue flexibility than a tension fascia splint. [ABSTRACT FROM AUTHOR]

The Modified Ashworth Scale (MAS) and Modified Tardieu Scale (MTS) are widely used to quantify spasticity. However, the reliability of their use for ankle plantar flexors has been questioned. In this study, we aimed to examine whether their reliabilities could be increased to acceptable levels for ankle plantar flexors using standardized movement speed in children with spastic cerebral palsy. The MAS and MTS scores for 92 limbs were assessed by two raters on two occasions, 1 week apart. A metronome was used to maintain the stretching velocity at 120 beats per minute. The intraclass correlation coefficients (ICCs) of the intra-rater reliabilities of the MAS and MTS and inter-rater reliability of the MAS were over 0.7. However, the ICCs for the inter-rater reliability of the MTS were <0.7 and >0.75 for the gastrocnemius and soleus muscles, respectively. The ICCs for the inter- and intra-rater reliabilities of the R1 angles ranged from 0.68 to 0.84, while those of the R2 angles ranged from 0.74 to 0.93. The reliabilities of the R2-R1 angles were not satisfactory. In conclusion, with a standardized movement speed, the reliability of the MAS for the ankle plantar flexors and the MTS for the soleus were satisfactory; however, that of the MTS for the gastrocnemius was not. [ABSTRACT FROM AUTHOR]

Objective: Regular exercise is a powerful tool that enhances skeletal muscle mass and strength. Lysine acetylation is an important post-translational modification (PTM) involved in a broad array of cellular functions. Skeletal muscle protein contains a considerable number of lysine-acetylated (Kac) sites, so we aimed to investigate the effects of exercise-induced lysine acetylation on skeletal muscle proteins. Methods: We randomly divided 20 male C57BL/6 mice into exercise and control groups. After 6 weeks of treadmill exercise, a lysine acetylation proteomics analysis of the gastrocnemius muscles of mice was performed. Results: A total of 2,254 lysine acetylation sites in 693 protein groups were identified, among which 1,916 sites in 528 proteins were quantified. The enrichment analysis suggested that protein acetylation could influence both structural and functional muscle protein properties. Moreover, molecular docking revealed that mimicking protein deacetylation primarily influenced the interaction between substrates and enzymes. Conclusion: Exercise-induced lysine acetylation appears to be a crucial contributor to the alteration of skeletal muscle protein binding free energy, suggesting that its modulation is a potential approach for improving exercise performance. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to identify the underpinning physiological and speed/mechanical determinants of different types of 800-m running time trials (i.e. with a positive or negative pacing strategy) and key components within each 800-m time trial (i.e. first and final 200 m). Methods: Twenty trained male 800-m runners (800-m personal best time (min:s): 1:55.10 +/- 0:04.44) completed a maximal 800-m time trial (800MAX) and one pacing trial, whereby runners were paced for the first lap, and speed was reduced by 7.5% (800PACE) relative to 800MAX, whereas the last lap was completed in the fastest time possible. Anaerobic speed reserve, running economy, the velocity corresponding with V[spacing dot above]O2peak (VV[spacing dot above]O2peak), maximal sprint speed (MAXSS), maximal accumulated oxygen deficit, and sprint force-velocity-power profiles were derived from laboratory and field testing. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus and expressed as a carnosine aggregate Z (CAZ) score to estimate muscle typology. Data were analyzed using multiple stepwise regression analysis. Results : MAXSS and vV[spacing dot above]O2peak largely explained the variation in 800MAX time (r 2 = 0.570; P = 0.020), whereas MAXSS was the best explanatory variable for the first 200-m time in 800MAX (adjusted r 2 = 0.661, P < 0.001). Runners with a higher CAZ score (i.e. higher estimated percentage of type II fibers) reduced their last lap time to a greater extent in 800PACE relative to 800MAX (adjusted r 2 = 0.413, P < 0.001), whereas better maintenance of mechanical effectiveness during sprinting, a higher CAZ score and vV[spacing dot above]O2peak was associated with a faster final 200-m time during 800PACE (adjusted r 2 = 0.761, P = 0.001). Conclusions: These findings highlight that diversity in the physiological and speed/mechanical characteristics of male middle-distance runners may be associated with their suitability for different 800-m racing strategies to have the best chance of winning. [ABSTRACT FROM AUTHOR]

Background. Aerobic exercise has been proven to have a positive effect on cardiac function after hypertension; however, the mechanism is not entirely clarified. Skeletal muscle mass and microcirculation are closely associated with blood pressure and cardiac function. Objective. This study was designed to investigate the effects of aerobic exercise on the skeletal muscle capillary and muscle mass, to explore the possible mechanisms involved in exercise-induced mitigation of cardiac dysfunction in pressure overload mice. Methods. In this study, 60 BALB/C mice aged 8 weeks were randomly divided into 3 groups: control (CON), TAC, and TAC plus exercise (TAE) group and utilized transverse aortic constriction (TAC) to establish hypertensive model; meanwhile, treadmill training is used for aerobic exercise. After 5 days of recovery, mice in the TAE group were subjected to 10-week aerobic exercise. Carotid pressure and cardiac function were examined before mice were executed by Millar catheter and ultrasound, respectively. Muscle mass of gastrocnemius was weighed; cross-sectional area and the number of capillaries of gastrocnemius were detected by HE and immunohistochemistry, respectively. The mRNA and protein levels of VEGF in skeletal muscle were determined by RT-PCR and western blot, respectively. Results. We found that ① 10-week aerobic exercise counteracted hypertension and attenuated cardiac dysfunction in TAC-induced hypertensive mice; ② TAC decreased muscle mass of gastrocnemius and resulted in muscle atrophy, while 10-week aerobic exercise could reserve transverse aortic constriction-induced the decline of muscle mass and muscle atrophy; and ③ TAC reduced the number of capillaries and the protein level of VEGF in gastrocnemius, whereas 10-week aerobic exercise augmented the number of capillaries, the mRNA and protein levels of VEGF in mice were subjected to TAC surgery. Conclusions. This study indicates that 10-week aerobic exercise might fulfill its blood pressure-lowering effect via improving skeletal muscle microcirculation and increasing muscle mass. [ABSTRACT FROM AUTHOR]

Purpose: Runners naturally adopt a stride frequency closely corresponding with the stride frequency that minimizes energy consumption. Although the concept of self-optimization is well recognized, we lack mechanistic insight into the association between stride frequency and energy consumption. Altering stride frequency affects lower extremity joint power; however, these alterations are different between joints, possibly with counteracting effects on the energy consumption during ground contact and swing. Here, we investigated the effects of changing stride frequency from a joint-level perspective. Methods: Seventeen experienced runners performed six running trials at five different stride frequencies (preferred stride frequency (PSF) twice, PSF ± 8%, PSF ± 15%) at 12 km⋅h-1. During each trial, we measured metabolic energy consumption and muscle activation, and collected kinematic and kinetic data, which allowed us to calculate average positive joint power using inverse dynamics. Results: With decreasing stride frequency, average positive ankle and knee power during ground contact increased (P < 0.01), whereas average positive hip power during leg swing decreased (P <0.01). Average soleus muscle activation during ground contact also decreased with increasing stride frequency (P < 0.01). In addition, the relative contribution of positive ankle power to the total positive joint power during ground contact decreased (P = 0.01) with decreasing stride frequency, whereas the relative contribution of the hip during the full stride increased (P < 0.01) with increasing stride frequency. Conclusions: Our results provide evidence for the hypothesis that the optimal stride frequency represents a trade-off between minimizing the energy consumption during ground contact, associated with higher stride frequencies, without excessively increasing the cost of leg swing or reducing the time available to produce the necessary forces. [ABSTRACT FROM AUTHOR]

Background. It is not known if foot structure may change after an Achilles tendon rupture and if a possible change may have an impact on lower limb function. The primary aim of the study was to explore the difference in foot structure between injured and healthy limb and between two treatment groups, at mean 6 years after an Achilles tendon rupture. A secondary aim was to explore if the differences in foot structure correlated with functional and clinical outcome. Methods. Ninety patients (15 women) with the mean (SD) age of 49 (9) years were evaluated. They had all been randomized to be treated with (n = 45) or without (n = 45) surgery. Foot structure was evaluated with Navicular Drop (Ndrop) and Drift (Ndrift), Longitudinal Arch Angle (LAA) and standing Dorsiflexion with knee straight and bent (DFstraight) and (DFbent). Calf muscle performance was evaluated with Single-leg standing heel-rise test and tendon length with ultrasound. For Patient-reported outcome measurements, Achilles tendon Total Rupture Score (ATRS) and Physical Activity Scale (PAS) were used. Both limbs were evaluated and the limb symmetry index (LSI (%) = injured/healthy x 100) was calculated. Results. In all patients, the injured limb demonstrated lower values (injured/healthy) in Ndrift (6.0/6.7 mm, p = 0.034), Ndrop (6.6/7.4 mm, p = 0.32) and DFbent (44/46°, p < 0.001). In the group treated with surgery, there was significant difference between limbs in DFbent (44/46°, p = 0.002). In the non-surgically treated group, the injured limb demonstrated significantly lower values in Ndrift (6.0/7.4 mm, p = 0.005), Ndrop (6.9/8.2 mm, p = 0.005) and DFbent (44/46°, p = 0.008). There was no difference between treatment groups in LSI-values. Conclusions. An Achilles tendon rupture seems to have an impact on foot structure long time after the injury. There is a need to clarify if the injury influences both feet and if there is a difference between treatment groups. [ABSTRACT FROM AUTHOR]

Introduction: This study examined the effects of 24 wk of daily static stretching of the plantarflexors (unilateral 4 _ 60-s stretching, whereas the contralateral leg served as a control; n = 26) on joint range of motion (ROM), muscle-tendon unit morphological and mechanical properties, neural activation, and contractile function. Methods: Torque-angle/velocity was obtained in passive and active conditions using isokinetic dynamometry, where as muscle-tendon morphology and mechanical properties were examined using ultrasonography. Results: After the intervention, ROM increased (stretching, +11° ± 7°; control, 4° ± 8°), and passive torque (stretching, -10 ± 11 N⋅m; control, -7 ± 10 N⋅m) and normalized EMG amplitude (stretching, -3% ± 6%; control, -3% ± 4%) at a standardized dorsiflexion angle decreased. Increases were seen in passive tendon elongation at a standardized force (stretching, +1.3 ± 1.6 mm; control, +1.4 ± 2.1 mm) and in maximal passive muscle and tendon elongation. Angle of peak torque shifted toward dorsiflexion. No changes were seen in tendon stiffness, resting tendon length, or gastrocnemius medialis fascicle length. Conformable changes in ROM, passive dorsiflexion variables, tendon elongation, and angle of peak torque were observed in the nonstretched leg. Conclusions: The present findings indicate that habitual stretching increases ROM and decreases passive torque, altering muscle-tendon behavior with the potential to modify contractile function. [ABSTRACT FROM AUTHOR]

Background: McKenzie back extension exercises from prone position has been widely prescribed for patients with lumbosacral radiculopathy (LSR). It has been reported to reduce radicular symptoms. Such reduction might indicate that decompression effect of this exercise on the compromised nerve root. The aim of this study was to evaluate the effect of McKenzie back extension exercise from prone position on soleus H-reflex of patients with LSR. Patient and Method: Seventeen male and Thirteen female patients (46.27±10.13 years) with confirmed chronic unilateral LSR participated in the study. All patients had done thirty repetitions of McKenzie back exercise from prone position. The soleus H-reflex was measured before and after the exercise. The Hreflex was elicited by electrical stimulation of the tibial nerve on the popliteal fossa of each legs. The non-involved leg of the patient was used as a control. Subjective pain intensity and sit-to-stand performance were additionally measured before and after back extension exercise using numerical pain analog scale and a stopwatch respectively. Results: The H-reflex latency within the affected leg showed significant difference after the exercise (p <0.05). The pain intensity and the sit-to-stand test had shown significant changes following exercise (p < 0.05). Conclusion: This study could indicate that the McKenzie repeated back extension exercises the manner performed in this study had improved the H-reflex, pain intensity or functional level of the patients. [ABSTRACT FROM AUTHOR]

Many studies have investigated the relationship between hypertension and its association with muscle health, showing controversial results on the subject. It is believed that high blood pressure can reduce the blood supply and cause damage to the arteries that supply areas of the motor cortex, responsible for muscle contraction and mobility, leading to a decay of functionality and reduced oxygen consumption and muscle strength. However, during aging there is a natural decrease in muscle mass, strength and quality, associated with the process of sarcopenia, although there are still difficulties identifying which factors are responsible for causing and worsening this process. In this context, it is believed that hypertension may play an important role in understanding this issue. compare isokinetic muscle function, muscle mass and gait speed among normotensive and hypertensive older adults. A cross-sectional observational study was conducted with 81 community-dwelling older adults selected by convenience. Participants were older people capable of walking without assistance and without cognitive alterations detectable by the Mini-Mental State Examination (MMSE). The diagnosis of arterial hypertension (independent variable) was made through the self-report of the participant´s previous medical diagnosis of arterial hypertension, validated by the record of using antihypertensive medication. The dependent variables of the study were: peak torque, muscle power, work by body weight and agonist-antagonist ratio of hip, knee and ankle (isokinetic dynamometry), handgrip strength (handgrip dynamometry), muscle mass (calf circumference) and usual gait speed at 10 meters. The dependent variables were compared between the groups of normotensive and hypertensive older adults by means of simple analyses and covariance adjusted for sex. most participants were female (51.9%), active (53.1%) and hypertensive (74%). In the simple analyses, it was observed that the hypertensive older group presented lower handgrip strength, lower mean peak torque of hip extensors and knee flexors, lower muscle power of knee flexors and extensors, lower work by body weight of hip flexors and knee extensors and lower knee agonist-antagonist ratio. However, in the analysis of covariance adjusted for sex, only in the knee agonist-antagonist ratio was found a statistically significant difference between the groups (40.64±9.01 vs 45.78±7.34; p=0.040). The study identified a lower knee agonist-antagonist ratio in hypertensive older adults when compared to normotensive patients. Our findings are linked to changes in muscle functioning that reflect uncoordinated activation of knee agonists and antagonists, although such changes cannot be fully explained by a significant reduction in strength. The understanding of hypertension and its impacts on muscle health contributes to a better understanding of the factors that cause and worsen the decline of muscle function in the older adults, in addition to being a potential contributor to the planning of health care strategies for the older people with a focus on the prevention and correct prescription of physical exercises. [ABSTRACT FROM AUTHOR]

The in vivo characterization of the passive mechanical properties of the human triceps surae musculotendinous unit is important for gaining a deeper understanding of the interactive responses of the tendon and muscle tissues to loading during passive stretching. This study sought to quantify a comprehensive set of passive muscle-tendon properties such as slack length, stiffness, and the stress-strain relationship using a combination of ultrasound imaging and a three-dimensional motion capture system in healthy adults. By measuring tendon length, the cross-section areas of the Achilles tendon subcompartments (i.e., medial gastrocnemius and soleus aspects), and the ankle torque simultaneously, the mechanical properties of each individual compartment can be specifically identified. We found that the medial gastrocnemius (GM) and soleus (SOL) aspects of the Achilles tendon have similar mechanical properties in terms of slack angle (GM: − 10.96 ° ± 3.48 ° ; SOL: − 8.50 ° ± 4.03 ° ), moment arm at 0° of ankle angle (GM: 30.35 ± 6.42 mm; SOL: 31.39 ± 6.42 mm), and stiffness (GM: 23.18 ± 13.46 Nmm-1; SOL: 31.57 ± 13.26 Nmm-1). However, maximal tendon stress in the GM was significantly less than that in SOL (GM: 2.96 ± 1.50 MPa; SOL: 4.90 ± 1.88 MPa, p = 0.024), largely due to the higher passive force observed in the soleus compartment (GM: 99.89 ± 39.50 N; SOL: 174.59 ± 79.54 N, p = 0.020). Moreover, the tendon contributed to more than half of the total muscle-tendon unit lengthening during the passive stretch. This unequal passive stress between the medial gastrocnemius and the soleus tendon might contribute to the asymmetrical loading and deformation of the Achilles tendon during motion reported in the literature. Such information is relevant to understanding the Achilles tendon function and loading profile in pathological populations in the future. [ABSTRACT FROM AUTHOR]

Background. Dystrophic skeletal muscle undergoes fast degeneration and therapeutic exercise is controversial in this condition. The aim of this study was investigate the effects of a low-intensity training protocol on muscle fibrosis and function of the mdx model. Methods. Mdx male animals with 8 weeks of age were (T0; n=8) underwent a protocol of eight weeks at a horizontal treadmill (9 m/min, 3x/week, 30 min/day). Mdx animals were randomly allocated at the Trained group (mdx-T, n=8) or sedentary (mdx-NT, n=8). In vivo functional measurements of strength and performance, immunolocalization of TGF-β1 and histomorphometry of intramuscular collagen fibers were assessed over time of protocol (T0, T4, T8) on Tibial Anterior (TA) and Soleus (SOL). Results. Strength decreased after 4 weeks of training (T4) and was regained at T8 at mdx-T. The percentage of intramuscular collagen fibers area decreased at SOL muscle of mdx-T at T4 when compared to T0 (p=0,025) and TA of mdx-T had a lesser area at T8 when compared to TA of mdx-NT group (p=0,002). TGF-β1 was observed at the sarcoplasm of TA and SOL muscles of mdx-NT group, with an age-dependent change. Conclusions. Treadmill low-intensity training provoked dystrophic skeletal muscle adaptation of fibrosis and maintained grip strength of the mdx model. [ABSTRACT FROM AUTHOR]

About 20% of individuals with autism spectrum disorders (ASD) showed tip-toe behavior (TTB). This behavior may be related to a decreased ankle joint range of motion (ROM) in dorsiflexion. Physiologically, gastrocnemius (GM) and soleus (SM) muscles influence ankle ROM independently. However, no studies investigated the relationship between the amount of time individuals with ASD spend in TTB and GM and SM muscle lengths. To evaluate the relationship between three mutually exclusive clinical patterns of TTB i.e., during standing, walking and running (TTB Class 1), or during walking and running (TTB Class 2), or only when running (TTB Class 3), and GM and SM muscle lengths. Sixty-nine individuals with ASD (average age: 14.1 ± 3.6 years, 56 males) were enrolled. In a clinical setting, SM and GM muscle lengths of both legs were assessed through a manual goniometer. Measurements were performed by two trained assessors blinded to TTB classifications. Individuals with ASD classified as TTB Class 1 demonstrated a shortening of both GM and SM compared with NO-TTB and TTB Class 3 individuals. Our results support the relationship between TTB severity and GM and SM shortening assessed by a decreased ankle joint ROM in dorsiflexion. Further studies are needed to determine the factors associated with TTB and decreased ankle ROM. [ABSTRACT FROM AUTHOR]

Damage to intramuscular tendons is very common in sports injuries, specifically in soleus muscle injuries. This study sought to compare the effects of applying ultrasound- (US-) guided percutaneous needle electrolysis (PNE) in combination with an eccentric exercise program on pain and functionality in dancers with chronic soleus injury, located in the central tendon. Thirty dancers with injured central tendon of the soleus muscle were randomly allocated to a PNE group (n = 10), an eccentric exercise group (n = 10), or a combined group (n = 10). Pain, ankle dorsiflexion range of motion (DROM), endurance, the heel raise test, the DFOS questionnaire, and the minimal clinically important difference (MCID) were analyzed at baseline and after treatment (four weeks). Over half (52%) of the dancers had a chronic soleus muscle injury. Variables for pain, DROM, the heel rise test, ADL, technique, DFOS total, and DFOS-subjective variables showed significant differences (P < 0.05) in pretreatment and posttreatment in all groups, whereas no significant differences were observed between intervention groups. However, the combined group showed a higher percentage of changes compared to the other groups, and these dancers had greater perceived changes (MCID = 4.70 ± 1.42). The conclusion of the study was that dancers with chronic soleus injury, located in the central tendon, treated with a combination of US-guided PNE and an eccentric exercise program displayed improved outcomes compared to the application of PNE therapy or eccentric exercise alone. The US-guided PNE, combined with an eccentric exercise program, is a useful therapeutic tool for the treatment of chronic soleus injury, located in the central tendon. The trial is registered with NCT04042012. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Introduction: Athletes returning to sport after anterior cruciate ligament reconstruction (ACLR) demonstrate prolonged changes in landing kinematics, kinetics, and muscle activation, predisposing them for reinjury, knee osteoarthritis, and/or knee instability. So far, researchers have been focusing on how kinematics and kinetics change in every joint separately. However, as the human body operates within a kinetic chain, we will assess whether single-joint changes are associated with whole-body changes. Methods: Twenty-one athletes who had an ACLR and 21 uninjured controls performed five unilateral landing tasks, whereas lower limb kinematics, kinetics, and muscle activations of vastus medialis, vastus lateralis, biceps femoris, semitendinosus, semimembranosus, gastrocnemius, and gluteus medius were recorded. Single-joint landing kinematics, kinetics, and muscle activations of the ACL-injured leg were compared with the uninjured leg and compared with the control group. Whole-body changes were assessed by decomposing movements into fundamental components using marker-based principal component analysis (PCA). Results: We found several single-joint changes in landing kinematics, kinetics, and muscle activations in the athletes with ACLR that were seen across all tasks and therefore of major interest as they are likely to occur during sports as well. Hamstrings activation increased and external knee flexion moments decreased in the ACL-injured leg compared with their uninjured leg. Furthermore, hip adduction moments and knee abduction angles decreased compared with the control group. The PCA could detect changes in whole-body movement, which were task-specific. Conclusions: Athletes with ACLR still show protective task-independent single-joint kinematic, kinetic, and muscle activation changes during single-leg landings at the time of return to sport. These single-joint changes were not consistently accompanied by changes in whole-body movements (revealed by marker-based PCA). Whole-body expressions of the single-joint compensations are likely to be affected by the demands of the task. [ABSTRACT FROM AUTHOR]

Background & aims: The Global Leadership Initiative on Malnutrition (GLIM) is new criteria for diagnosing malnutrition that need validation adjusted to race. Our aim is to determine the optimal reference values of calf circumference (CC), investigate the prevalence of GLIM-defined malnutrition based on different screening tools in inpatients over 70 years old in China and assess its relationship with clinical outcomes. Methods: We designed two continuity studies by analyzing a prospective multicenter database. First, we estimated and validated the CC cut-off values by receiver operating characteristic analyses against in-hospital mortality. Then the patients who were at risk by NRS 2002, MNA-SF and MUST were assessed by the GLIM criteria using the new CC values. Some clinical parameters and outcome data were evaluated. Results: The optimal cut-off values of CC were 29.6 cm for male patients and 27.5 cm for female patients. The prevalence of GLIM-defined malnutrition was 27.5% by using NRS2002, 32.6% by using MNA-SF and 25.4% by using MUST. Patients with GLIM-defined malnutrition showed significantly worse values in BMI, total protein, albumin, neutrophil/lymphocyte ratio, CC, rate of complication, in-hospital mortality, length of stay, and total hospital cost than normal patients. Multivariate logistic regression showed the odds ratio of in-hospital mortality was significantly associated with GLIM defined malnutrition by using MNA-SF [OR = 1.231, 95%CI (1.022, 1.484), P = 0.029]. Conclusions: The Chinese reference values of CC for inpatients over 70 years old were validated by in-hospital mortality, which could be implemented in GLIM criteria. And this population possessed a high prevalence of nutrition risk and malnutrition. GLIM criteria with MNA-SF seems to be the first choice to diagnose malnutrition. [ABSTRACT FROM AUTHOR]

• Unloader brace did not change co-contraction of agonist and antagonist muscles. • Unloader brace produced changes in gluteal and gastrocnemius timing and amplitude, however, the clinical relevance is unclear. • There were no differences between adjusted and unadjusted brace conditions. To determine the immediate effects of a varus unloader knee brace on lower-limb electromyographic activity in individuals with lateral knee osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction. Electromyographic data were recorded in 19 individuals with lateral knee osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction during walking under three conditions: (i) no brace, (ii) unadjusted brace (no varus adjustment), and adjusted brace (varus adjustment). Variables of interest were statistically analyzed using repeated measures analysis of variance. There were no significant differences in muscle co-contraction between the three test conditions. The adjusted brace resulted in delayed offset of gluteus maximus (mean difference [95% CI]: 72 ms [24, 119]), and earlier onset of gluteus medius (59 ms [21, 97]) compared to no brace. The adjusted brace delayed onset of lateral gastrocnemius compared to no brace (53 ms [28, 78]) and the unadjusted brace (39 ms [7, 71]) and reduced average activation amplitude of gluteus maximus (−4 mV [−6, −1]) and lateral gastrocnemius (−9 mV [−16, −2]) compared to no brace. The unloader brace did not produce significant changes in muscle co-contraction in individuals with lateral knee osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction. Significant changes in gluteal and gastrocnemius muscle activation timing and amplitude were observed, however, it is not clear whether these changes are of clinical importance. [ABSTRACT FROM AUTHOR]

Dynamic stretching (DS) is performed to increase sports performance and is also used primarily for transiently increasing range of motion (ROM). Recently, vibration foam rolling (VFR) has emerged. Its underlying concept is that it combines foam rolling techniques with local vibration to improve ROM and muscular activation concurrently. This crossover study investigated the effects of DS or DS followed by VFR (DS + VFR) during warm-ups on flexibility, muscle stiffness, power, and agility of the lower limbs in badminton athletes. Forty badminton players performed DS or DS + VFR as warmup exercises on two occasions in a randomized order. The target muscle groups were the bilateral shoulder, anterior and posterior thigh, posterior calf, and lower back. Main outcome measures: The primary outcome was knee range of motion (ROM), and the secondary outcomes were muscle stiffness, lower limb power (countermovement jump [CMJ]), and agility. Results indicated that the protocols improved performance. DS increased knee flexion ROM (% change = 1.92, ES = 0.3, p = 0.033), CMJ height (% change = 5.04, ES = 0.2, p = 0.004), and agility (% change = -4.97, ES = 0.4, p < 0.001) but increased quadriceps muscle stiffness (% change = 3.74, ES = 0.3, p = 0.001) and increased gastrocnemius muscle stiffness (% change = 10.39, ES = 0.5, p = 0.001). DS + VFR increased knee extension ROM (% change =2.87, ES = 0.4, p = 0.003), reduced quadriceps muscle stiffness (% change = -2.79, ES = 0.3, p = 0.017), CMJ height (% change = 2.41, ES = 0.1, p = 0.037), and agility (% change = -4.74, ES = 0.2, p < 0.001). DS + VFR was not significantly superior to DS, except for muscle stiffness reduction. Taken together, we suggest that practitioners consider DS as a first line of warm-up exercise to increase ROM, CMJ height, and agility in athletes. Moreover, the addition of VFR to DS results in a large reduction of muscle stiffness, potentially reducing the risk of sports injury. Athletes, coaches and athletic professionals may consider them when selecting effective warm-up practices to augment athletic performance. [ABSTRACT FROM AUTHOR]

An acute bout of distance running decreases Achilles tendon CSA. The purpose of this study was to examine if three-week stretch training of the Achilles tendon alters the Achilles tendon thinning response to running. Thirty-three recreational runners were divided into a control group (n = 17) and an intervention group (n = 16). The intervention included a three-week soleus stretch (knee flexed) and gastrocnemius stretch (knee extended). Three gastrocnemius stretches and three soleus stretches were performed each day, six days per week. Stretches were held for 30 s per repetition for a total duration of 180 s per leg per day. Achilles tendon CSA and range of motion measures were completed pre and post-run before and after the three-week stretching intervention. The runs prior to and following the three-week stretch training intervention both resulted in a 6% decrease in Achilles tendon CSA (p < 0.0001). There was no interaction across time between control and intervention groups in CSA (p = 0.446). Only the intervention group experienced a significant increase in dorsiflexion range of motion following the stretch training (p = 0.009). We therefore conclude that even when an increased dorsiflexion range of motion occurs, three weeks of triceps surae stretching does not alter the response of the Achilles tendon CSA. [ABSTRACT FROM AUTHOR]