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The Nordic Hamstring Exercise (NHE) effectively strengthens the knee flexors. Typically conducted without assistance, extended knee angles are not reached with sustained muscle activation in the presence of insufficient eccentric strength and/or fatigue. This might impair the desired neuromuscular adaptations and assessment accuracy. This study investigated kinetic and kinematic differences between assisted and unassisted NHEs (3 × 3 repetitions) performed by sixteen male sprinters (22 years, 181 cm, 76 kg). Kinetic (peak moment, impulse) and kinematic parameters (e.g., time under tension, range of motion to excessive downward acceleration (ROMDWA) were investigated. All analysed parameters significantly differed between assisted and unassisted NHEs (p ≤ 0.003; 0.635≤ ηp² ≤ 0.929) favouring assisted execution, except for peak moments and maximal hip flexion. Repetition 1 of assisted NHEs revealed 21% higher impulses rising to 82% during repetition 9. Equivalent interactions of mode and repetition became apparent for time under tension, ROMDWA, mean and fractional angular velocity. Unassisted NHEs elicited substantially greater inter-repetition fatigue (rep1 vs. rep9): +79% fractional angular velocity (d = 1.01), −41% impulse (d = 1.53), −31% ROMDWA (d = 0.99) and −29% time under tension (d = 1.45). Assisted NHEs ensured higher execution quality and lower between-participant variability by facilitating a controlled full-ROM movement. Three sets of 3 NHEs sufficed to induce substantial fatigue within and across sets. [ABSTRACT FROM AUTHOR]

Eccentric quasi-isometric (EQI) contractions (maintaining a yielding contraction for as long as possible, beyond task failure) have gained interest in research and applied settings. However, little is known regarding the biomechanical profile of EQIs. Fourteen well-trained males performed four maximal effort knee-extensor EQIs, separated by 180 seconds. Angular impulse, velocity, and time-under-tension through the 30–100º range of motion (ROM), and in eight ROM brackets were quantified. Statistical parametric mapping, analyses of variance, and standardised effects (Hedges' g (ES), %Δ) detected between-contraction joint-angle-specific differences in time-normalised and absolute variables. Mean velocity was 1.34º·s−1 with most (62.5 ± 4.9%) of the angular impulse imparted between 40–70º. Most between-contraction changes occurred between 30–50º (p≤ 0.067, ES = 0.53 ± 0.31, 60 ± 52%), while measures remained constant between 50–100º (= 0.069–0.83, ES = 0.10 ± 0.26, 14.3 ± 24.6%). EQIs are a time-efficient means to impart high cumulative mechanical tension, especially at short to medium muscle lengths. However, angular impulse distribution shifts towards medium to long muscle lengths with repeat contractions. Practitioners may utilise EQIs to emphasize the initial portion of the ROM, and limit ROM, or apply EQIs in a fatigued state to emphasize longer muscle lengths. [ABSTRACT FROM AUTHOR]

Les Mills BODYPUMPTM is a resistance training group exercise class with a low load, high repetition format. Squat training in BODYPUMPTM has two key variables: depth and load. The study aim was to determine the effect of these parameters on the mean and peak EMG amplitude of vastus lateralis, gluteus maximus, biceps femoris and lateral gastrocnemius. Ten female BODYPUMPTM participants (age 41 ± 9 years, height 161.9 ± 3.8 cm, mass 67.7 ± 7.0 kg) performed 1 × 7 squats under four conditions, representing every combination of two depths (90° knee angle and 125° knee angle) and two loads (23% bodyweight and 38% bodyweight). The main effect of depth was significant for mean and peak activity of vastus lateralis and gluteus maximus, and peak activity of biceps femoris and lateral gastrocnemius. The main effect of load was significant for mean and peak activity of gluteus maximus and lateral gastrocnemius. There was no depth * load interaction. These data can be used to inform BODYPUMPTM programme design and amplify the training effect of participation in group exercise classes. [ABSTRACT FROM AUTHOR]

Portable data collection devices and machine learning (ML) have been combined in autonomous movement analysis models for resistance training (RT) movements. However, input features for these models were mostly extracted empirically and subsequent models demonstrated limited interpretability and generalisability to real-world settings. This study aimed to investigate the utility of interpretable and generalisable modelling techniques and several data-driven feature extraction (FE) methods. This was achieved by developing machine learning movement analysis models for the barbell back squat and deadlift using markerless motion capture. 61 participants performed submaximal and maximal repetitions of both RT movements. Movement data was collected using two Azure Kinect cameras. Joint and segment kinematic variables were calculated from the collected depth imaging, and input features were extracted using traditional, manual FE methods and novel data-driven techniques. Classifiers were developed for several predefined technical deviations for both movements. Many of the addressed technical deviations could be classified with good levels of accuracy (≥70%) while the remainder were poor (55%–60%). Additionally, data-driven FE techniques were comparable to previous, traditional FE methods. Interpretable and generalisable modelling techniques can be utilised to good effect for certain classification tasks while data-driven FE techniques did not provide a consistent advantage over traditional FE methods. [ABSTRACT FROM AUTHOR]

The potential for high performance in many sports can be assessed by quantifying whole-body explosiveness. The backwards overhead medicine ball (BOMB) throw is commonly-used to tests this ability, but the effect of varied loading on test execution is unknown. The purpose of this study was to determine the effect of different medicine ball (MB) loads on force, velocity, and power output during the BOMB throw. Female collegiate softball and rugby players (n=31) performed the BOMB throw on a force plate using 2.7, 3.6, 4.5, and 5.5 kg MBs, with three throws per load in a randomised order, and 30 seconds rest between throws. A series of Repeated Measures ANOVAs noted no differences (p>0.05) in peak power, peak force, peak velocity, force at the moment of peak power, or velocity at the moment of peak power, across MB loads. The lack of differences among these loads indicates that coaches can likely compare kinetic characteristics of the BOMB throw within this range (2.7-5.5 kg). Therefore, coaches can use the BOMB throw with 2.7-5.5 kg MBs for training or measurement among female athletes to obtain reference data for programming or evaluation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare one repetition maximum (1RM), a rating of discomfort, and myoelectric activity between self-selected and experimentally controlled speeds and grip widths during the bench press (BP). Four BP conditions used were self-selected speed and grip (SS), self-selected speed and experimentally controlled grip (SC), experimentally controlled speed and self-selected grip (CS), and experimentally controlled speed and grip (CC). Twenty male individuals completed 1RM measurements with each BP condition and then performed 16 BP trials (four trials per condition) for measuring myoelectric activity. A one-way repeated measures analysis of variance was conducted for 1RM. Frequency analyses were conducted for a rating of discomfort. Two-way repeated measures multivariate analyses of variance were performed for myoelectric activity. SS showed a significantly higher 1RM than SC, CS, and CC. CC was characterised as the most uncomfortable BP condition (80%) followed by CS (15%), SC (5%), and SS (0%). There were no significant main effects and interaction of speed and width on myoelectric activity. A self-selected speed and grip width was recommended because it would allow a more practical and ecologically valid assessment of 1RM and a lower rating of discomfort during the BP. [ABSTRACT FROM AUTHOR]

This study aimed to compare the effect of three interset rest intervals (1, 3, and 5 minutes) on (I) mean velocity during a resistance training session conducted in a Smith machine with the squat and bench press exercises, and (II) the pre- and post-exercise force-velocity relationship. Fifteen male university students completed three sessions (i.e., Rest 1ʹ, Rest 3ʹ, and Rest 5ʹ) consisting of three sets of five repetitions against the 10RM load during the squat and bench press exercises. The force-velocity relationship (maximal values of force [F0], velocity [v0], and power [Pmax]) was evaluated at the beginning and at the end of each session with the countermovement jump and bench press throw exercises. During training, mean velocity was slower in sets 2 and 3 of the Rest 1ʹ protocol compared to Rest 3ʹ and Rest 5ʹ, but no significant differences were present between Rest 3ʹ and Rest 5ʹ. After training, there was a significant decrease in F0 (p = 0.017) and Pmax (p = 0.010), but not in v0 (p = 0.259). These results support the Rest 3ʹ as the most time-efficient protocol, among those analysed, for the maintenance of high mean velocities during training sessions not leading to failure. [ABSTRACT FROM AUTHOR]

Resistance exercise on Earth commonly involves both body weight and external load. When developing exercise routines and devices for use in space, the absence of body weight is not always adequately considered. This study compared musculoskeletal load distribution during two flywheel resistance knee-extension exercises, performed in the direction of (vertical squat; S) or perpendicular to (horizontal leg press; LP) the gravity vector. Eleven participants performed these two exercises at a given submaximal load. Motion analysis and musculoskeletal modelling were used to compute joint loads and to simulate a weightless situation. The flywheel load was more than twice as high in LP as in S (p < 0.001). Joint moments and forces were greater during LP than during S in the ankle, hip and lower back (p < 0.01) but were similar in the knee. In the simulated weightless situation, hip and lower-back loadings in S were higher than corresponding values at Earth gravity (p ≤ 0.01), whereas LP joint loads did not increase. The results suggest that LP is a better terrestrial analogue than S for knee-extension exercise in weightlessness and that the magnitude and direction of gravity during resistance exercise should be considered when designing and evaluating countermeasure exercise routines and devices for space. [ABSTRACT FROM AUTHOR]

The assessment of the mechanical power production is of great importance for researchers and practitioners. The purpose of this review was to compare the differences in ground reaction force (GRF), kinematic, and combined (bar velocity x GRF) methods to assess mechanical power production during weightlifting exercises. A search of electronic databases was conducted to identify all publications up to 31 May 2019. The peak power output (PPO) was selected as the key variable. The exercises included in this review were clean variations, which includes the hang power clean (HPC), power clean (PC) and clean. A total of 26 articles met the inclusion criteria with 53.9% using the GRF, 38.5% combined, and 30.8% the kinematic method. Articles were evaluated and descriptively analysed to enable comparison between methods. The three methods have inherent methodological differences in the data analysis and measurement systems, which suggests that these methods should not be used interchangeably to assess PPO in Watts during weightlifting exercises. In addition, this review provides evidence and rationale for the use of the GRF to assess power production applied to the system mass while the kinematic method may be more appropriate when looking to assess only the power applied to the barbell. [ABSTRACT FROM AUTHOR]

The kettlebell swing is a complex exercise shown to provide cardiovascular and strength benefits. However, novice kinematic pattern differences might limit the effectiveness of the kettlebell swing to fully realise those benefits. The purpose of this study was to assess how novices self-directed their learning of the kettlebell swing using only an instructional video. Twelve young adults performed kettlebell swings sets over one week. We captured kinematic data of their first sets without practice, sets within-day following practice, and sets one week later following practice. The subjects received no augmented feedback. Ankle, knee, hip, and shoulder mean and variability kinematics were compared. In addition, the relative timing of peak sagittal plane angular velocity of the hip and shoulder was evaluated to determine whether the hips led to the shoulders. Within-day subjects reduced hip and shoulder peak extension, knee and hip peak flexion, and hip peak flexion velocity. Between-day subjects reduced mean hip peak flexion and range of motion, as well as peak knee flexion. Our results suggest novices prioritised improving consistency early in practice and then adjusted their kinematic pattern over the week. Moreover, most subjects transitioned to the hips leading shoulders, suggesting this is a perceivable coordination pattern by intrinsic feedback. [ABSTRACT FROM AUTHOR]

This study aimed to compare the changes in body composition and physical qualities of under 19’s backs and forwards during the season (i.e. from pre-season [Pre-S] to end-season [End-S]). Twenty-seven male youth rugby union players (mean ± SD: age, Forwards [n = 11]: 17.5 ± 1.2 and Backs [n = 16]: 17.0 ± 0.9 years) participated in this study. Participants were tested twice (i.e. at Pre-S and End-S) and completed: anthropometric, body composition, countermovement and squat jumps, 30-m sprint, squat and bench press 1-repetition maximum (SQ-1RM and BP-1RM). Significant differences were observed between Pre-S and End-S for body mass (BM) and lean mass (LM), among both playing positions (p < 0.034; ES > 0.71), whereas all other variables remained unchanged. Regarding physical performance, backs and forwards showed greater SQ-1RM and BP-1RM, respectively (p < 0.043; ES>-0.69). Moreover, backs and forwards exhibited higher split times from 5 to 30 m (p: 0.013 to <0.001). Substantial increases were observed in BM and LM for backs and forwards, which may have negatively impacted acceleration (i.e. 5-m sprint time) and initial sprint momentum for both playing positions. Our findings highlight the importance of carefully balancing changes in BM and body composition, to avoiding the detrimental effects of these variations on sprint performance. [ABSTRACT FROM AUTHOR]

Targeted muscle strengthening might improve performance or help overcome training stagnation; therefore, the aim of the present study was to investigate changes in muscle activity patterns before and after six weeks of targeted resistance training. Twenty-seven resistance-trained men were divided into three groups according to their prime mover activity, as measured by surface electromyography during a bench press (BP). Each group underwent a six-week block of targeted exercises for one of the following muscles: anterior deltoid (AD), pectoralis major (PM) or triceps brachii (TB). ANOVA showed that each group increased their 1 repetition maximum (1RM) (p < 0.05) and the activity of the exercised muscle group during an isometric bench press (p < 0.01) and during a dynamic bench press (p < 0.01) at 85% of the 1RM. During the isometric BP, the TB training group had an increase in TB activity in comparison to the other groups. Targeted muscle training is a useful method for muscle activity increase and increasing the maximum strength in complex exercise, when applied in activity-deficient muscle groups. Strengthening the TB elicits changes in all prime movers and results in TB activity domination during a bench press. [ABSTRACT FROM AUTHOR]

Performing the bench-press (BP) exercise in a weight stack machine (WSM) is a common practice. However, no previous studies have analysed the load-velocity relationship in this BP variant. The purpose of this study was 1) to investigate the load-velocity relationship during BP exercise using a WSM; and 2) to compare the load-velocity relationship in this exercise in two conditions: WSM vs. Smith machine (SM). Twenty-six young men performed a BP progressive loading test to determine their one-repetition maximum and load-velocity relationship using a WSM. Additionally, 19 participants performed two progressive loading tests (WSM and SM). A high relationship was found between the relative load (%1RM) and mean propulsive velocity (MPV) (R2 = 0.97; SEE = 0.07 m/s) in the WSM. Moreover, significant differences were observed (p <.05) in the MPV values attained in every %1RM in WSM and SM from 30 to 75% 1RM. The close relationship between the MPV values and the %1RM in BP exercise using a WSM enables coaches to use the MPV to accurately monitor their athletes on a daily basis. The differences observed between WSM and SM in the %1RM and their respective MPVs indicate that different equations must be used for each exercise mode. [ABSTRACT FROM AUTHOR]

This study determined the acute changes in rotational work with thigh attached wearable resistance (WR) of 2% body mass during 50-m sprint-running. Fourteen athletes completed sprints with, and without, WR in a randomised order. Sprint times were measured via timing gates at 10-m and 50-m. Rotational kinematics were obtained over three phases (steps 1–2, 3–6 and 7–10) via inertial measurement unit attached to the left thigh. Quantification of thigh angular displacement and peak thigh angular velocity was subsequently derived to measure rotational work. The WR condition was found to increase sprint times at 10-m (1.4%, effect size [ES] 0.38, p 0.06) and 50-m (1.9%, ES 0.55, p 0.04). The WR condition resulted in trivial to small increases in angular displacement of the thigh during all phases (0.6–3.4%, ES 0.04–0.26, p 0.09–0.91). A significant decrease in angular velocity of the thigh was found in all step phases (−2.5% to −8.0%, ES 0.17–0.51, p < 0.001–0.04), except extension in step phase 1 with the WR. Rotational work was increased (9.8–18.8%, ES 0.35–0.53, p < 0.001) with WR in all phases of the sprint. Thigh attached WR provides a means to significantly increase rotational work specific to sprinting. [ABSTRACT FROM AUTHOR]

The aim of this acute cross-sectional study was to quantify the kinematic and kinetic changes that occur during sprint acceleration when lower body WR is worn. Fifteen male rugby athletes (19 years; 181 cm; 91 kg) were assessed during maximal effort over−ground and treadmill sprinting over 20 m under three different loading conditions: 0%, 3% and 5% body mass (BM) added weight attached to the lower body. Treadmill data provided a convenient estimate of kinetic changes in the absence of in-ground force plates. The loaded conditions resulted in significantly increased ground contact time (5 to 6%) and decreased step frequency (−2 to −3%) during sprint accelerations (effect size = 0.32–0.72). Moderate WR loading (3% BM) resulted in increased (9%; effect size = 0.66) theoretical maximum horizontal force (relative to BM) and unchanged 20 m sprint times (p > 0.05). Heavier WR loading (5% BM) resulted in a significant decrease (−4%) in vertical ground reaction forces (relative to total system mass) and slower (1 to 2%) 20 m sprint times (effect size = 0.38–0.70). Lower body WR loading up to 5% BM can provide specific sprint training overload, while affecting sprint acceleration biomechanics by ≤ 6%. [ABSTRACT FROM AUTHOR]

Traditional sets can be fatiguing, but redistributing rest periods to be shorter and more frequent may help maintain peak vertical barbell displacement (DISP) and reduce concentric repetition duration (CRDI), peak velocity decline (PVD) and perceptual exertion (RPE) across multiple repetitions, sets and loads during clean pulls. Fifteen strength-trained men performed: 3 traditional sets of 6 clean pulls using 80% (TS80), 100% (TS100) and 120% (TS120) of power clean 1RM with 180 seconds of inter-set rest; and 3 'rest redistribution' protocols of 9 sets of 2 clean pulls using 80% (RR80), 100% (RR100) and 120% (RR120) of power clean 1RM with 45 seconds of inter-set rest. DISP was greater during RR100 (g = 0.39) and RR120 (g = 0.56) compared to TS100 and TS120, respectively. In addition, PVD was less during RR120 than TS120 (g = 1.18), while CRDI was greater during TS100 (g = 0.98) and TS120 (g = 0.89) compared to RR100 and RR120, respectively. Also, RR protocols resulted in lower RPE across the sets at all loads (g = 1.11–1.24). Therefore, RR generally resulted in lower perceptual and mechanical fatigue, evidenced by lower RPE, PVD, CRDI and greater DISP than TS, and these differences became even more exaggerated as the barbell load and the number of sets performed increased. [ABSTRACT FROM AUTHOR]

Functional training aims to provide specific adaptations due to exercise training and utilises a variety of equipment, including kettlebells. Due to the training principle of overload, a greater resistance must be applied to yield increased strength results. This study examined the effects of kettlebell mass on lower body joint kinetics in young recreationally trained adults. Thirty recreationally active, college-aged adults were recruited for this study. Participants performed hip-hinge style swings with kettlebells equivalent to 10%, 15% and 20% of their respective body mass. 3-D marker coordinate data were captured via infrared camera system and ground reaction force data were measured with two force plates. The resultant joint moments of the lower body were calculated using the inverse dynamics procedure. As mass increased, there was an increase in joint moment at the L4/5, hip and ankle joint, primarily due to an increase in ground reaction force. Increasing kettlebell mass can potentially cause greater strength gains in the hip and trunk musculature due to increase in lower body moments, while avoiding excessive moments about the knee. [ABSTRACT FROM AUTHOR]

The article presents the discussion on correction notice ""Acute changes in acceleration phase sprint biomechanics with lower body wearable resistance."

The aims of the study were to evaluate the relative and absolute variability of upper (T11-L2) and lower (L2-S2) lumbar spinal alignment in power- and weightlifters during the deadlift and back squat exercises, and to compare this alignment between the two lifting groups. Twenty-four competitive powerlifters (n = 14) and weightlifters (n = 10) performed three repetitions of the deadlift and the back squat exercises using a load equivalent to 70% of their respective one-repetition maximum. The main outcome measures were the three-dimensional lumbar spinal alignment for start position, minimum and maximum angle of their spinal alignment, and range of motion measured using inertial measurement units. Relative intra-trial reliability was calculated using the two-way random model intraclass correlation coefficient (ICC) and absolute reliability with minimal detectable change (MDC). The ICC ranged between 0.69 and 0.99 and the MDC between 1°-8° for the deadlift. Corresponding figures for the squat were 0.78–0.99 and 1°-6°. In all participants during both exercises, spinal adjustments were made in both thoracolumbar and lumbopelvic areas in all three dimensions. In conclusion, when performing three repetitions of the deadlift and the squat, lumbar spinal alignment of the lifters did not change much between repetitions and did not differ significantly between power- and weightlifters. [ABSTRACT FROM AUTHOR]

Flywheel-based iso-inertial training (FIT) has been purported to provide enhanced adaptations to muscle overload compared to dynamic constant external resistance (DCER), but previous studies have not controlled for exercise intensity. We compared quadriceps electromyography (EMG) amplitude between FIT- and DCER-squats with similar tempo. Eleven (5 M and 6F) resistance-trained participants completed sets of five maximal velocity FIT (0.025 kg∙m2) and DCER (55 ± 15 %1RM) squats. Sagittal plane knee joint angles and surface EMG activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) were measured. Repetition time and peak knee angles were similar between FIT and DCER squats. Mean knee angular velocity during the concentric (122.2 ± 23.6 vs. 108.9 ± 22.9, p = 0.022, Cohen’s D: 0.820), but not eccentric, phase was significantly greater during FIT. Peak VM (210.4 ± 49.3 vs. 177.5 ± 56.3 %MVIC, p = 0.001; Cohen’s D: 1.416), but not VL or RF, EMG amplitude was significantly greater in FIT compared to DCER. Mean EMG amplitude was significantly (p < 0.001) greater during the concentric than the eccentric phase for the VL and VM but not RF. Mean EMG amplitude was not significantly different between modes during either the concentric or eccentric phase. Quadriceps EMG amplitude is largely similar between FIT and DCER squats when matched for movement velocity. [ABSTRACT FROM AUTHOR]

This systematic review aimed to quantify the acute and longitudinal effects that occur with weighted vests during sprint-running. PubMed, SPORTDiscus, and Web of Science were searched using the Boolean phrases (vest OR trunk) AND (sprint*) AND (resist* OR weight OR load*). From 170 articles retrieved, 11 studies (6 acute, 5 longitudinal) met the inclusion criteria. Vest loads (5–40% body mass) were found to significantly increase acute over-ground times (10–50 m 4.1–16.9%, effect sizes [ES] = 0.93–3.11) through significantly decreased velocity (−2.2% to −17.3%, ES = −0.41 to −3.19), horizontal force (−5.9% to −22.1%, ES = −0.85 to −3.30), maximal power (−4.3% to −35.6%, ES = −0.32 to −3.44), and flight times (−8.3% to −14.6%, ES = −0.88 to −1.03), while increasing contact times (14.7–19.6%, ES = 1.80–3.17). Treadmill sprints were less effected until loads >11% body mass were used. Improvements in velocity (1.2–1.3%, ES = 0.24–0.37) and times (10–50 m 1.2–9.4%, ES = 0.25–3.30) were found in longitudinal studies (5.6–18.9% body mass, 3–7 weeks). Future studies should focus on determining the optimum load and volume to clearly establish the training benefits of this form of resisted sprinting. [ABSTRACT FROM AUTHOR]

The manipulation of the volume and intensity of static stretching (SS) can affect the range of motion (ROM) and muscle force output. The purpose of this study was to investigate the effect of two different SS protocols with different intensities (50% and 85% POD) and volumes (120-s and 240-s) on ROM, peak force, and muscle activity during maximal isometric leg curl exercise in well-trained participants. Fifteen young males (age:27.5 ± 6.1years, height:175.6 ± 4.7cm, and body mass:81.5 ± 10.4kg, 6 ± 2 years of resistance training experience) performed passive hip flexion with two different SS protocols: six stretches of 40-s, with 15-sec rest between each stretch at 50% of the point of discomfort (POD) and three stretches of 40-s, with 15-sec rest between each stretch at 85%POD. The passive hip flexion ROM, biceps femoris muscle activation (integrated electromyography: IEMG), and knee flexors force were monitored during a 3-s maximal voluntary isometric leg curl exercise. ROM increased between pre- and post-intervention for both SS protocols (50%POD: p = 0.016, Δ% = 4.6% and 85%POD: p < 0.001, Δ% = 11.42%). Peak force decreased between pre- and post-intervention only for 85%POD (p = 0.004, Δ% = 23.6%). There were no significant IEMG differences. In conclusion, both SS protocols increased ROM, however, the high-intensity and short-duration SS protocol decreased peak force. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effects of shank mass manipulation on the sprinting technique in maximal-speed sprinting. Sixteen well-trained male athletes sprinted with and without an additional 15% of shank mass attached to the shank centre of mass. Kinematic data were collected using a 12-camera motion analysis system and analysed using linear regression analyses with categorical variables and paired t-tests. The sprinting speed (p < 0.01), knee flexion angle at landing (p = 0.028), and maximum hip flexion angular velocity (p = 0.029) decreased; contact time (p < 0.01) increased; and step length, step frequency, and other analysed technique measures of maximal-speed sprinting were unchanged (p ≥ 0.12) with shank mass manipulation, compare with no manipulation. The relationships of sprinting speed with critical linear and angular kinematics at landing, take-off and swing in maximal-speed sprinting were not affected by the shank mass manipulation. These results suggest that 15% shank mass manipulation does not change the sprinting technique of well-trained male athletes in maximal-speed sprinting. This supports the use of shank mass manipulation as a training method for well-trained sprinters; however, a change in correlations between sprinting speed and technique measures should be considered during such training. [ABSTRACT FROM AUTHOR]

This randomised controlled study examined the force–velocity relationship changes (force and velocity axis intercepts, slope and estimated maximum power) in response to 5-week training programmes differing in the set configuration. For each session, the traditional group performed 4 sets of 8 repetitions with 5 min of rest between sets and exercises, while the cluster group completed 16 sets of 2 repetitions with 1 min of rest between sets and 5 min between exercises. Both programmes were performed with the 10-repetition maximum load, including bench press, parallel squat, lat pull-down and leg curl exercises. Individual force-velocity profiles were obtained for bench press and squat using a linear velocity transducer before and after the intervention, along with lactate and mechanical performance during the intervention. Results showed in bench press similar changes of the force-velocity profile after both protocols (no shift of the slope and higher force and velocity axis intercept values). For the squat, significant changes in the slope (P = 0.001) and the velocity intercept (P = 0.002) towards a velocity profile were observed after cluster but not after traditional training. These results suggest that set configuration may modulate changes of force–velocity relationship, especially for squat. [ABSTRACT FROM AUTHOR]

The objective of the study was to investigate the effects of using lifting straps on the lat pull-down exercise on maximal strength, number of repetitions, and muscle activation. Twelve resistance-trained men participated (age 27 ± 4 years, body mass 84 ± 10 kg, height 177 ± 6 cm, resistance training experience 6.6 ± 2.4 years). All participants performed the 1RM tests and training protocols either with the lifting straps (WS) or without (WOS). Exercise sessions for both conditions (WS and WOS) consisted of 3 sets to concentric failure with a load of 70% of one repetition maximum (1RM) and rest intervals of 60 s. For the 1RM test, no difference was observed between WS and WOS conditions (96.5 ± 12.7 kg and 96.6 ± 11.9 kg, respectively). There were no differences between the WS and WOS conditions in the number of repetitions per set, total repetitions and latissimus dorsi muscle activation. In conclusion, the findings of this study demonstrate that the use of lifting straps in the lat pull-down exercise by resistance-trained individuals does not promote beneficial effect in the 1RM value, the number of repetitions performed with 70% of 1RM, and muscle activation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyse the reliability and validity of an opto-electronic sensor system (Velowin) for assessment of the bar-velocity in the deep squat exercise. Mean velocity, mean propulsive velocity and peak velocity generated in the deep squat exercise performed in the Smith machine bar were analysed compared to a linear velocity transducer considered as the gold standard. The study was conducted with a sample of 26 men with experience in resistance training. Six measurements were analysed for squat exercise in concentric phase using a progressive loading increase. Three consecutive repetitions were performed per load with a 3–4 min recovery between loads. Analysis of variance confirmed that there were no significant differences (p > 0.05) for the velocity variables between Velowin and T-Force for each of the loads. The reliability analysis showed high values of the intraclass correlation coefficient (ICC = 0.94–0.99), an 'almost perfect' Lin's concordance coefficient (CCC = 0.99) and a low coefficient of variation (CV <3.4%) for each of the loads and velocities. These results confirm the reliability and validity of the Velowin device for measuring the execution velocity in deep squat exercise. [ABSTRACT FROM AUTHOR]

An introduction is presented which discusses articles in the issue on topics including, need for a more sensitive analysis to determine clinical differences between the techniques; and Para Powerlifting athletes and individuals with scoliosis or structural bone deformations.