Search

Purpose : Phase contrast magnetic resonance imaging (PC-MRI) represents an opportunity to non-invasively investigate cerebral spinal fluid (CSF) flow in patients with idiopathic normal pressure hydrocephalus (iNPH). Studies in recent years have explored the diagnostic and prognostic value of PC-MRI derived parameters. This review aims to identify all PC-MRI studies of iNPH published since 2010, synthesise a review based on collated results, and analyse specific flow parameters identified in the selected studies. Methods: Our protocol was prospectively registered on PROSPERO [CRD42020180826]. We systematically searched four databases: Pubmed, Web of Science, Ovid, and Cochrane library to identify all eligible studies. Quality assessment was performed using a modified Newcastle–Ottawa Scale [19]. Systematic review was conducted according to Prisma guidelines. A random-effects model was used to perform meta-analysis on the available flow parameters. Results: Eighteen records were identified for inclusion. Five studies were eligible for meta-analysis, representing 107 iNPH patients and 82 controls. CSF flow parameters available for analysis were stroke volume and peak velocity. Both were significantly higher than controls (p = 0.0007 and p = 0.0045 respectively) according to our random-effects analysis, consistent with a model of hyper-dynamic CSF in iNPH. Our systematic review revealed average stroke volumes in iNPH ranging from 43uL to over 200uL. Peak velocity values ranged from 5.9 cm/s to 12.8 cm/s. Conclusion: Significant increases in stroke volume and peak velocity values in iNPH patients suggest a place for PC-MRI as supplementary evidence in the diagnostic work-up of iNPH. Although shunting reduces aqueductal stroke volume and peak velocity, the ability of pre-shunt values to reliably predict treatment response remains complicated. We suggest that it may be more appropriate to consider a range of values that reflect varying probabilities of shunt success. We recommend that future studies should prioritise standardising PC-MRI protocols, and before then PC-MRI findings should be considered supportive rather than determinative. [ABSTRACT FROM AUTHOR]

The practice of the wheelchair rugby is becoming more and more worldwide. However, few biomechanical studies have focused on this sport. The aim of this study was to compare kinematic parameters of wheelchair rugby players, classified as defensive players (LP-D) versus offensive players (HP-O). Twenty-nine wheelchair rugby players (17 LP-D and 12 HP-O) performed a 20-m sprint test. The peak velocities, temporal parameters (propulsion phase time, deceleration phase time, cycle time and cycle frequencies) and asymmetries (the difference in peak velocities between the right and the left wheels) were measured at the acceleration and constant peak velocity phases of the sprint by an inertial measurement unit which was placed on each rear wheel. At the acceleration and constant peak velocity phases, peak velocities and cycle frequencies were higher in HP-O players than LP-D players. The deceleration phase times and the cycle times were higher in LP-D players than HP-O players. However, no significant difference in asymmetry was found between LP-D players and HP-O players. The HP-O players showed superior performance than the LP-D players, but they could be more exposed at risk of injury at their upper limbs than LP-D players. [ABSTRACT FROM AUTHOR]

Objective: The aim of the studywas to evaluate the influence of repeated sprints on kinematic performance and propulsion variables during the acceleration and constant peak velocity phases in wheelchair rugby players classified as defensive (low point in defensive [LP-D]) or offensive players (high point in offensive [HP-O]). Design: Twenty-two players (13 LP-D and 9 HP-O) performed 6° 20-m repeated sprint field tests. We calculated peak wheelchair velocities, propulsion phase times, deceleration phase times, cycle times, and left-right velocity asymmetry of the best and last sprints during the acceleration and constant peak velocity phases, the rate of decline in performance variables between the best and the last sprint and a fatigue index. Results: Peak velocities during the acceleration and constant peak velocity phases and mean velocity over thewhole sprint were significantly higher during the best than last sprint. Peak velocities were higher during the acceleration and constant peak velocity phases for the best and last sprint for HP-O. The rate of decline in peak velocity during the constant peak velocity phasewas higher for LP-D. Fatigue index and rate of decline in velocities and sprint time were higher for LP-D. Conclusions: Performance variables and the rate of decline in performance variables depended on functional capacity and wheelchair type. [ABSTRACT FROM AUTHOR]

Objective: The main purpose of this study was to evaluate and compare the in-hospital, 1-month and 1-year post-procedure outcomes of patients treated with Evolut-R 34 mm and Evolut-R 23/26/29 mm devices. Additionally, the study aimed to identify factors that could predict the occurrence of = mild paravalvular leaks (PVL). Methods: Between April 2015 and May 2022, 269 consecutive patients who underwent transcatheter aortic valve implantation (TAVI) with Evolut-R 34 mm (n = 66, 24.5%) and Evolut-R 23/26/29 mm (n = 203, 75.5%) devices in a single center were retrospectively analyzed. Results: Patients in the Evolut-R 34 mm group had a lower female sex ratio (16.7% vs. 66.5%, P < .001, respectively), ejection fraction (50.7 ± 10.1% vs. 54.5 ± 9.3%, P = .016, respectively), and mean aortic gradient (7.4 ± 3.3 vs. 9.2 ± 5.0, P = .026, respectively) compared to the Evolut-R 23/26/29 mm group. The groups did not exhibit any statistically significant distinctions with regard to technical success, the need for a permanent pacemaker, occurrences of stroke, major vascular complications, PVL, major adverse cardiovascular and cerebrovascular events, or mortality. Peak velocity was confirmed as a significant predictor of =mild PVL in both patient groups in the receiver operating characteristic curve analysis. In logistic regression analysis; In patients with Evolut-R 34 mm valve, pre-TAVI aortic valve peak velocity (odds ratio (OR) = 23.202; P = .019) and calcium volume 800 Hounsfield Units (mm3) (OR = 1.017; P < .001) were independent predictors of =mild PVL. Conclusion: The Evolut-R 34 mm valve has shown comparable in-hospital results with smaller valve sizes. Pre-TAVI aortic valve peak velocity and calcium volume predicted = mild PVL in Evolut-R 34 mm patients. [ABSTRACT FROM AUTHOR]

The aims of this study were to: (a) determine the differences in external load quantification between arbitrary and individual speed thresholds over the weekly microcycle in professional soccer players, and (b) analyse the association between internal load and different external load quantification strategies (ELQSs). Ten professional outfield players were monitored during training sessions and official matches using 10 Hz GPS devices over a 6-week in-season period. The absolute and relative ("R" before the distance category) distances covered were calculated for the following external load variables: medium-intensity running distance (MIR), highintensity running (HIR), sprint distance (SD), and very high-intensity running (VHIR). Individualized thresholds were determined based on maximal sprinting speed (MSS) and the last speed achieved during the 30-15 Intermittent Fitness Test (VIFT) of each player. In terms of match-day workload, significant differences (p < 0.05) were observed between arbitrary and individualized strategies (i.e., MSS and VIFT) for the distance covered in MIR, HIR, SD, VHIR, RHIR, RSD, and RVHIR. The MSS strategy compared to arbitrary thresholds revealed significant differences (p < 0.05) for distance covered in HIR, RHIR, and VHIR during all training sessions. The present results showed that arbitrary thresholds lead to underestimation of external load absolute and relative metrics compared to the MSS strategy throughout the microcycle. The VIFT strategy mainly revealed differences in external load quantification regarding MD compared to arbitrary thresholds. Individualized speed threshold strategies did not achieve better associations with internal load measures in comparison with arbitrary thresholds in professional soccer players. [ABSTRACT FROM AUTHOR]

Background: The purpose of the study was to determine the relationship between the Kinematic parameter (Peak Velocity during Counter Movement Jump (CMJ)) with Agility Run and Short Sprint Acceleration Run. Material and Method: Total of 124 (66 males and 58 females) hockey trainees performed CMJ on Force Platform followed by 5-m short sprint acceleration and 6 m × 10 m shuttle run. Pearson's correlation was calculated, and the level of significance was kept at P ≤ 0.05. Results: The correlation of peak velocity with short sprint acceleration run and agility run was found as r = −0.542 and r = −0.457, respectively, for all subjects, while male hockey trainees demonstrated the values of r = −0.794 and −0.699, whereas the female hockey trainees indicated the values of r = −0.632 and r = −0.575 with short sprint acceleration run and agility run, respectively. Conclusion: The present study concluded that peak velocity had a linear correlation with short sprint acceleration run as well as agility run. This could be a fruitful result for coaches as well as players to inculcate the vertical Jump regime in their training program so as to improve the performance of the players. [ABSTRACT FROM AUTHOR]

We investigated the influence of advance lunging in fencing from the perspective of velocity and lower limb joint angles to identify how the joint angles contribute to the peak velocity in a lunge with advance (LWA). Fourteen skilled athletes (age: 19.6 ± 0.9 years, height: 171.2 cm ± 5.2 cm, weight: 63.7 kg ± 5.3 kg, and fencing experience: 9.7 ± 3.1 years) participated by performing two types of attacking movements, and data were collected with a 3D movement analysis system. A correlation between the peak velocity of the body center of mass (CoM) in an advance lunge and several joint angle variables (rear hip peak flexion angle (r = 0.63), rear ankle peak dorsiflexion angle (r = −0.66), rear ankle range of motion (r = −0.59), and front hip peak extension angle (r = 0.54)) was revealed. In addition, the joint angle variables that significantly predicted peak CoM velocity during an LWA were the rear knee peak flexion angle (β = 0.542), rear knee peak extension angle (β = −0.537), and front knee peak extension angle (β = −0.460). Our findings suggest that the rear leg hip joint, rear leg ankle joint, and front leg hip joint may control the acceleration generated by an LWA. Furthermore, more flexion of the rear leg knee joint in the early phase of the lunge and greater extension of the rear and front leg knee joints at the end of the lunge phase may help increase peak velocity.

The aims of this study were to: (a) determine the differences in external load quantification between arbitrary and individual speed thresholds over the weekly microcycle in professional soccer players, and (b) analyse the association between internal load and different external load quantification strategies (ELQSs). Ten professional outfield players were monitored during training sessions and official matches using 10 Hz GPS devices over a 6-week in-season period. The absolute and relative (“R” before the distance category) distances covered were calculated for the following external load variables: medium-intensity running distance (MIR), highintensity running (HIR), sprint distance (SD), and very high-intensity running (VHIR). Individualized thresholds were determined based on maximal sprinting speed (MSS) and the last speed achieved during the 30–15 Intermittent Fitness Test (V IFT ) of each player. In terms of match-day workload, significant differences (p < 0.05) were observed between arbitrary and individualized strategies (i.e., MSS and V IFT ) for the distance covered in MIR, HIR, SD, VHIR, RHIR, RSD, and RVHIR. The MSS strategy compared to arbitrary thresholds revealed significant differences (p < 0.05) for distance covered in HIR, RHIR, and VHIR during all training sessions. The present results showed that arbitrary thresholds lead to underestimation of external load absolute and relative metrics compared to the MSS strategy throughout the microcycle. The V IFT strategy mainly revealed differences in external load quantification regarding MD compared to arbitrary thresholds. Individualized speed threshold strategies did not achieve better associations with internal load measures in comparison with arbitrary thresholds in professional soccer players.

Purpose: This study aimed to examine the reliability and validity of load−velocity (L–V) relationship variables obtained through the 2-point method using different load combinations and velocity variables. Methods: Twenty men performed 2 identical sessions consisting of 2 countermovement jumps against 4 external loads (20 kg, 40 kg, 60 kg, and 80 kg) and a heavy squat against a load linked to a mean velocity (MV) of 0.55 m/s (load0.55). The L–V relationship variables (load-axis intercept (L0), velocity-axis intercept (v0), and area under the L–V relationship line (Aline)) were obtained using 3 velocity variables (MV, mean propulsive velocity (MPV), and peak velocity) by the multiple-point method including (20–40–60–80–load0.55) and excluding (20–40–60–80) the heavy squat, as well as from their respective 2-point methods (20–load0.55 and 20–80). Results: The L–V relationship variables were obtained with an acceptable reliability (coefficient of variation (CV) ≤ 7.30%; intra-class correlation coefficient ≥ 0.63). The reliability of L0 and v0 was comparable for both methods (CVratio (calculated as higher value/lower value): 1.11–1.12), but the multiple-point method provided Aline with a greater reliability (CVratio = 1.26). The use of a heavy squat provided the L–V relationship variables with a comparable or higher reliability than the use of a heavy countermovement jump load (CVratio: 1.06–1.19). The peak velocity provided the load–velocity relationship variables with the greatest reliability (CVratio: 1.15–1.86) followed by the MV (CVratio: 1.07–1.18), and finally the MPV. The 2-point methods only revealed an acceptable validity for the MV and MPV (effect size ≤ 0.19; Pearson's product-moment correlation coefficient ≥ 0.96; Lin's concordance correlation coefficient ≥ 0.94). Conclusion: The 2-point method obtained from a heavy squat load and MV or MPV is a quick, safe, and reliable procedure to evaluate the lower-body maximal neuromuscular capacities through the L–V relationship.

From November to December 2015, shaking table experiments were conducted on a ten-story reinforced-concrete building to acquire useful data for developing advanced technology for seismic structures and to investigate numerical analysis models. Two structural system types, which are a free-standing base-sliding and conventional seismic structure system, were used in this experiment; the second system was the same building as the first, but with a fixed base. The specimen building was subjected to Kobe earthquake motions with amplitudes of 10%, 25%, 50%, 100%, and 60%. The experimental results of the free-standing base-sliding and conventional seismic structures were compared, and regression analysis was conducted on the relationship between the seismic performance of each structure and seismic intensity. During the Kobe earthquake with 100% amplitude, the peak maximum inter-story drift ratio of the free-standing base-sliding was smaller than that of the conventional seismic structure. The acceleration response distributions for the free-standing base-sliding and conventional seismic structure system experiments with smaller amplitudes were similar to the distribution provided by the Architectural Institute of Japan. The shear force coefficient at the base-sliding surface did not fluctuate significantly, despite the increase in sliding velocity. According to the regression analysis results, the global rotation stiffness ratio and equivalent story stiffness ratio of each story may be related to the cumulative value of the peak velocity of the shaking table; further, the peak maximum inter-story drift ratio may be linearly related to the seismic intensity. [ABSTRACT FROM AUTHOR]

We investigated the influence of advance lunging in fencing from the perspective of velocity and lower limb joint angles to identify how the joint angles contribute to the peak velocity in a lunge with advance (LWA). Fourteen skilled athletes (age: 19.6 ± 0.9 years, height: 171.2 cm ± 5.2 cm, weight: 63.7 kg ± 5.3 kg, and fencing experience: 9.7 ± 3.1 years) participated by performing two types of attacking movements, and data were collected with a 3D movement analysis system. A correlation between the peak velocity of the body center of mass (CoM) in an advance lunge and several joint angle variables (rear hip peak flexion angle (r = 0.63), rear ankle peak dorsiflexion angle (r = −0.66), rear ankle range of motion (r = −0.59), and front hip peak extension angle (r = 0.54)) was revealed. In addition, the joint angle variables that significantly predicted peak CoM velocity during an LWA were the rear knee peak flexion angle (β = 0.542), rear knee peak extension angle (β = −0.537), and front knee peak extension angle (β = −0.460). Our findings suggest that the rear leg hip joint, rear leg ankle joint, and front leg hip joint may control the acceleration generated by an LWA. Furthermore, more flexion of the rear leg knee joint in the early phase of the lunge and greater extension of the rear and front leg knee joints at the end of the lunge phase may help increase peak velocity. [ABSTRACT FROM AUTHOR]

Older adults who report a fear of falling are more likely to subsequently fall, yet, some gait anxiety-related alterations may protect balance. We examined the effect of age on walking in anxiety-inducing virtual reality (VR) settings. We predicted a high elevation-related postural threat would impair gait in older age, and differences in cognitive and physical function would relate to the observed effects. Altogether, 24 adults (age (y) = 49.2 (18.7), 13 women) walked on a 2.2-m walkway at self-selected and fast speeds at low (ground) and high (15 m) VR elevation. Self-reported cognitive and somatic anxiety and mental effort were greater at high elevations (all p < 0.001), but age- and speed-related effects were not observed. At high VR elevations, participants walked slower, took shorter steps, and reduced turning speed (all p < 0.001). Significant interactions with age in gait speed and step length showed that relatively older adults walked slower (β = − 0.05, p = 0.024) and took shorter steps (β = − 0.05, p = 0.001) at self-selected speeds at high compared to low elevation settings. The effect of Age on gait speed and step length disappeared between self-selected and fast speeds and at high elevation. At self-selected speeds, older adults took shorter and slower steps at high elevation without changing step width, suggesting that in threatening settings relatively older people change gait parameters to promote stability. At fast speeds, older adults walked like relatively younger adults (or young adults walked like older adults) supporting the notion that people opt to walk faster in a way that still protects balance and stability in threatening settings. [ABSTRACT FROM AUTHOR]

• The load−velocity relationship variables (L 0 , v 0 , and A line) are obtained with an acceptable reliability during the countermovement jump exercise regardless of the method (multiple-point vs. 2-point), load combination (heavy-squat vs. heavy countermovement jump), and velocity variable (mean velocity vs. mean propulsive velocity vs. peak velocity). • The concurrent validity of the 2-point method with respect to the multiple-point method was only acceptable for mean velocities. • The 2-point method obtained from a heavy squat load and mean velocities is a quick, safe, and reliable procedure to evaluate the maximal neuromuscular capacities of lower-body muscles through the assessment of the load−velocity relationship variables. This study aimed to examine the reliability and validity of load−velocity (L–V) relationship variables obtained through the 2-point method using different load combinations and velocity variables. Twenty men performed 2 identical sessions consisting of 2 countermovement jumps against 4 external loads (20 kg, 40 kg, 60 kg, and 80 kg) and a heavy squat against a load linked to a mean velocity (MV) of 0.55 m/s (load 0.55). The L–V relationship variables (load-axis intercept (L 0), velocity-axis intercept (v 0), and area under the L–V relationship line (A line)) were obtained using 3 velocity variables (MV, mean propulsive velocity (MPV), and peak velocity) by the multiple-point method including (20–40–60–80–load 0.55) and excluding (20–40–60–80) the heavy squat, as well as from their respective 2-point methods (20–load 0.55 and 20–80). The L–V relationship variables were obtained with an acceptable reliability (coefficient of variation (CV) ≤ 7.30%; intra-class correlation coefficient ≥ 0.63). The reliability of L 0 and v 0 was comparable for both methods (CV ratio (calculated as higher value/lower value): 1.11–1.12), but the multiple-point method provided A line with a greater reliability (CV ratio = 1.26). The use of a heavy squat provided the L–V relationship variables with a comparable or higher reliability than the use of a heavy countermovement jump load (CV ratio : 1.06–1.19). The peak velocity provided the load–velocity relationship variables with the greatest reliability (CV ratio : 1.15–1.86) followed by the MV (CV ratio : 1.07–1.18), and finally the MPV. The 2-point methods only revealed an acceptable validity for the MV and MPV (effect size ≤ 0.19; Pearson's product-moment correlation coefficient ≥ 0.96; Lin's concordance correlation coefficient ≥ 0.94). The 2-point method obtained from a heavy squat load and MV or MPV is a quick, safe, and reliable procedure to evaluate the lower-body maximal neuromuscular capacities through the L–V relationship. [Display omitted] [ABSTRACT FROM AUTHOR]

Warm-up is important for increasing athlete performance, preventing injuries and rehabilitation. Different methods are used for warm-up. In professional soccer, warming up has an important place in preventing injuries while increasing performance. The effect of warm-up on performance, endurance and injuries is still controversial. Today, conventional warm-up (CWU), FIFA11+ and self myofascial release (SMR) methods are frequently used for warm-up and rehabilitation. The aim of this study was to evaluate the effects of CWU, FIFA11+ and FIFA11+ plus SMR (F+SMR) methods on endurance in soccer players. The study included 16 licensed amateur male soccer players (Age: 17.00±00 years, Height: 174.12±5.89 cm, weight: 60.87±8.09 kg, Body Mass Index: 20.01±1.90) who regularly trained five times a week and played one official competition. CWU, FIFA 11+ and F+SMR sessions were performed on different days, respectively. Care was taken to ensure that the soccer players were not tired during the practice. After each warm-up session, the 30-15 intermittent fitness test was performed and its effects on endurance were evaluated. When running times, peak velocities and maximal aerobic speeds were compared; it was found that running times after CWU were 12.3% higher than FIFA 11+ warm-up, while peak running speeds after FIFA 11+ warm-up were 6.3% lower than CWU warm-up. In terms of maximal aerobic speed, 7.1% higher values were found in CWU warm-up group compared to FIFA 11+ and 3.5% higher values compared to F+SMR. In conclusion, in terms of endurance performance of the athletes, CWU and F+SMR warm-up showed higher running speeds compared to FIFA 11+ warm-up session. The results of the study show that CWU gives better results in terms of endurance and FIFA11+ warm-up method may be insufficient in this respect. It can be speculated that it is important for coaches to apply different warm-up methods for different purposes in the performance of soccer players. [ABSTRACT FROM AUTHOR]

Abstract Background Measurement of peak velocities is important in the evaluation of heart failure. This study compared the performance of automated 4D flow cardiac MRI (CMR) with traditional transthoracic Doppler echocardiography (TTE) for the measurement of mitral inflow peak diastolic velocities. Methods Patients with Doppler echocardiography and 4D flow cardiac magnetic resonance data were included retrospectively. An established automated technique was used to segment the left ventricular transvalvular flow using short-axis cine stack of images. Peak mitral E-wave and peak mitral A-wave velocities were automatically derived using in-plane velocity maps of transvalvular flow. Additionally, we checked the agreement between peak mitral E-wave velocity derived by 4D flow CMR and Doppler echocardiography in patients with sinus rhythm and atrial fibrillation (AF) separately. Results Forty-eight patients were included (median age 69 years, IQR 63 to 76; 46% female). Data were split into three groups according to heart rhythm. The median peak E-wave mitral inflow velocity by automated 4D flow CMR was comparable with Doppler echocardiography in all patients (0.90 ± 0.43 m/s vs 0.94 ± 0.48 m/s, P = 0.132), sinus rhythm-only group (0.88 ± 0.35 m/s vs 0.86 ± 0.38 m/s, P = 0.54) and in AF-only group (1.33 ± 0.56 m/s vs 1.18 ± 0.47 m/s, P = 0.06). Peak A-wave mitral inflow velocity results had no significant difference between Doppler TTE and automated 4D flow CMR (0.81 ± 0.44 m/s vs 0.81 ± 0.53 m/s, P = 0.09) in all patients and sinus rhythm-only groups. Automated 4D flow CMR showed a significant correlation with TTE for measurement of peak E-wave in all patients group (r = 0.73, P

Most empirical formulae for the basin concentration time (Tc) and storage coefficient (K) focus on estimating the representative values under the ordinary condition, with their return period being a maximum of 100–200 years. Under more extreme conditions, those parameters should be modified to consider faster velocity conditions. The main objective of this study is to examine the possibility of determining these parameters corresponding to the given peak velocity (vp) at the basin outlet. Two issues are involved in this problem; one is whether Tc can be fully expressed by vp, while the other is whether K is still linearly proportional to Tc under extreme conditions. In this study, these two issues are resolved by the theoretical review of these parameters, as well as an analysis of the rainfall–runoff events collected at the Chungju Dam basin, Korea. It is observed that as vp increases, Tc and K decrease. Their relationship is close to inverse but in linear proportion. That is, strong linear relationships are found among Tc, K, and vp. As a result, the ratio of K to Tc is found to be almost identical, regardless of vp. This ratio at a basin can be assumed as a basin characteristic that is unchanged, regardless of the size of rainfall events. HIGHLIGHTS Strong linear relationships at the basin outlet are found among the basin concentration time, storage coefficient, and peak velocity.; The ratio of the storage coefficient to the concentration time is found to be almost identical, regardless of the peak velocity.; The ratio of the storage coefficient to the concentration time can be assumed as an unchanged basin characteristic, regardless of the size of rainfall events.;

This study aimed to compare sprint skating profile characteristics of the different playing positions of junior and senior bandy players. In total, 111 male nationallevel bandy players (age: 20.7 ± 5.0 years, height: 1.80 ± 0.05 m, body mass: 76.4 ± 0.4 kg, training experience: 13.8 ± 5.0 yrs) were tested on their sprint skating profile over 80 m. The main findings were that no differences between positions were found in sprint skating performance (speed and acceleration), but that elite players were in general heavier (p < 0.05) than junior players (80.0 ± 7.1 vs. 73.1 ± 8.1 kg), they could accelerate faster (2.96 ± 0.22 vs. 2.81 ± 0.28 m/s2), and they reached a higher velocity (10.83 ± 0.37 vs. 10.24 ± 0.42 m/s) earlier over 80mthan the junior players. This implies that junior level players should spend more time in power and sprint training to meet the specific demands of playing at a higher, elite level. [ABSTRACT FROM AUTHOR]

To ensure that large precision instruments and equipment are in the best working condition, it is necessary to provide a suitable working environment for them. At this time, there is a high requirement for the vibration of the foundation at the location. Measuring the foundation vibration parameters, analyzing the foundation vibration state, and taking necessary damping measures during the construction process to provide basis are the premise of equipment installation and normal work. Combined with an application example, this paper briefly introduces the general situation of a project blasting, and obtains the basic characteristic parameters such as the peak velocity of ground motion and the time of arrival during the blasting operation; Based on the basic principle of regression analysis, the relationship between the peak velocity and the distance between the detonation centers and the charge weight is obtained by fitting the Sadovsky formula. [ABSTRACT FROM AUTHOR]

This study aimed to compare sprint skating profile characteristics of the different playing positions of junior and senior bandy players. In total, 111 male national-level bandy players (age: 20.7 ± 5.0 years, height: 1.80 ± 0.05 m, body mass: 76.4 ± 0.4 kg, training experience: 13.8 ± 5.0 yrs) were tested on their sprint skating profile over 80 m. The main findings were that no differences between positions were found in sprint skating performance (speed and acceleration), but that elite players were in general heavier (p < 0.05) than junior players (80.0 ± 7.1 vs. 73.1 ± 8.1 kg), they could accelerate faster (2.96 ± 0.22 vs. 2.81 ± 0.28 m/s2), and they reached a higher velocity (10.83 ± 0.37 vs. 10.24 ± 0.42 m/s) earlier over 80 m than the junior players. This implies that junior level players should spend more time in power and sprint training to meet the specific demands of playing at a higher, elite level.

There is no research examining female bandy players, which creates a gap of knowledge of female skating performance and its determinants with male skating performance, not only in bandy but also in exercise science in general. Therefore, the aim of this explorative study was to investigate position and playing-level differences in the sprint skating performance and anthropometrics of 74 elite female bandy players (age: 18.9 ± 4.1 years; height: 1.67 ± 0.06 m; body mass: 63.2 ± 7.4 kg). Participants were categorised according to playing level (26 elite and 48 junior elite players) and position (22 defenders, 35 midfielders, and 17 forwards). They were tested on their anthropometric characteristics and sprint linear skating profile over 80mwith the split times measured at 10, 20, 40, 50, 60, 70, and 80mto calculate the average velocities between these different 10m intervals. Results revealed that elite players had more training experience, were heavier, could accelerate faster, and reached a higher maximal velocity than the junior elite players (9.52 ± 0.37 vs 8.84 ± 0.40 m/s, respectively). In general, defenders were heavier than forwards, and the elite forwards accelerated faster in the first 10m than the midfielders (p = 0.041). In summary, playing level and position, body mass, and training experience modulated skating sprint performance. The findings suggest that female junior-level players should spend more time developing skating sprint and acceleration abilities to meet the specific demands of playing at the elite level. Moreover, the coaches and professionals who work with female bandy players should be aware that the development of acceleration ability is more important for forwards. [ABSTRACT FROM AUTHOR]

Background: Measurement of peak velocities is important in the evaluation of heart failure. This study compared the performance of automated 4D flow cardiac MRI (CMR) with traditional transthoracic Doppler echocardiography (TTE) for the measurement of mitral inflow peak diastolic velocities. Methods: Patients with Doppler echocardiography and 4D flow cardiac magnetic resonance data were included retrospectively. An established automated technique was used to segment the left ventricular transvalvular flow using short-axis cine stack of images. Peak mitral E-wave and peak mitral A-wave velocities were automatically derived using in-plane velocity maps of transvalvular flow. Additionally, we checked the agreement between peak mitral E-wave velocity derived by 4D flow CMR and Doppler echocardiography in patients with sinus rhythm and atrial fibrillation (AF) separately. Results: Forty-eight patients were included (median age 69 years, IQR 63 to 76; 46% female). Data were split into three groups according to heart rhythm. The median peak E-wave mitral inflow velocity by automated 4D flow CMR was comparable with Doppler echocardiography in all patients (0.90 ± 0.43 m/s vs 0.94 ± 0.48 m/s, P = 0.132), sinus rhythm-only group (0.88 ± 0.35 m/s vs 0.86 ± 0.38 m/s, P = 0.54) and in AF-only group (1.33 ± 0.56 m/s vs 1.18 ± 0.47 m/s, P = 0.06). Peak A-wave mitral inflow velocity results had no significant difference between Doppler TTE and automated 4D flow CMR (0.81 ± 0.44 m/s vs 0.81 ± 0.53 m/s, P = 0.09) in all patients and sinus rhythm-only groups. Automated 4D flow CMR showed a significant correlation with TTE for measurement of peak E-wave in all patients group (r = 0.73, P < 0.001) and peak A-wave velocities (r = 0.88, P < 0.001). Moreover, there was a significant correlation between automated 4D flow CMR and TTE for peak-E wave velocity in sinus rhythm-only patients (r = 0.68, P < 0.001) and AF-only patients (r = 0.81, P = 0.014). Excellent intra-and inter-observer variability was demonstrated for both parameters. Conclusion: Automated dynamic peak mitral inflow diastolic velocity tracing using 4D flow CMR is comparable to Doppler echocardiography and has excellent repeatability for clinical use. However, 4D flow CMR can potentially underestimate peak velocity in patients with AF. [ABSTRACT FROM AUTHOR]

Aim: To compare 4D flow magnetic resonance imaging (MRI) and 2D phase contrast (PC) MRI when evaluating bicuspid (BAV) and tricuspid (TAV) aortic valves. Materials and Methods: A total of 83 subjects (35 BAV, 48 TAV) were explored with 4D flow and 2D PC MRI. Systolic peak velocity, peak flow and regurgitation fraction were analysed at two pre-defined aortic levels (aortic root, midtubular). Furthermore, the two methods of 4D flow analysis (Heart and Artery) were compared. Results: Correlation between the 2D PC MRI and 4D flow MRI derived parameters ranged from moderate (R=0.58) to high (R=0.90). 4D flow MRI yielded significantly higher peak velocities in the tubular aorta in both groups. Regarding the aortic root, peak velocities were significantly higher in the TAV group with 4D flow MRI, but in the BAV group 4D flow MRI yielded non-significantly lower values. Findings on peak flow differences between the two modalities followed the same pattern as the differences in peak velocities. 4D flow MRI derived regurgitation fraction values were lower in both locations in both groups. Interobserver agreement for different 4D flow MRI acquired parameters varied from poor (ICC=0.07) to excellent (ICC=1.0) in the aortic root, and it was excellent in the tubular aorta (ICC=0.8-1.0). Conclusion: 4D flow MRI seems to be accurate in comparison to 2D PC MRI in normal aortic valves and in BAV with mild to moderate stenosis. However, the varying interobserver reproducibility and impaired accuracy at higher flow velocities should be taken into account in clinical practice when using the 4D flow method. [ABSTRACT FROM AUTHOR]

There is no research examining female bandy players, which creates a gap of knowledge of female skating performance and its determinants with male skating performance, not only in bandy but also in exercise science in general. Therefore, the aim of this explorative study was to investigate position and playing-level differences in the sprint skating performance and anthropometrics of 74 elite female bandy players (age: 18.9 ± 4.1 years; height: 1.67 ± 0.06 m; body mass: 63.2 ± 7.4 kg). Participants were categorised according to playing level (26 elite and 48 junior elite players) and position (22 defenders, 35 midfielders, and 17 forwards). They were tested on their anthropometric characteristics and sprint linear skating profile over 80 m with the split times measured at 10, 20, 40, 50, 60, 70, and 80 m to calculate the average velocities between these different 10 m intervals. Results revealed that elite players had more training experience, were heavier, could accelerate faster, and reached a higher maximal velocity than the junior elite players (9.52 ± 0.37 vs 8.84 ± 0.40 m/s, respectively). In general, defenders were heavier than forwards, and the elite forwards accelerated faster in the first 10 m than the midfielders (p = 0.041). In summary, playing level and position, body mass, and training experience modulated skating sprint performance. The findings suggest that female junior-level players should spend more time developing skating sprint and acceleration abilities to meet the specific demands of playing at the elite level. Moreover, the coaches and professionals who work with female bandy players should be aware that the development of acceleration ability is more important for forwards.

Purpose: To examine the reliability of peak velocity (PV), mean propulsive velocity (MPV), and mean velocity (MV) in the development of load–velocity profiles (LVP) in the full-depth free-weight back squat performed with maximal concentric effort. Methods: Eighteen resistance-trained men performed a baseline 1-repetition maximum (1-RM) back-squat trial and 3 subsequent 1-RM trials used for reliability analyses, with 48-h intervals between trials. 1-RM trials comprised lifts from 6 relative loads including 20%, 40%, 60%, 80%, 90%, and 100% 1-RM. Individualized LVPs for PV, MPV, or MV were derived from loads that were highly reliable based on the following criteria: intraclass correlation coefficient (ICC) >.70, coefficient of variation (CV) ≤10%, and Cohen d effect size (ES) <0.60. Results: PV was highly reliable at all 6 loads. MPV and MV were highly reliable at 20%, 40%, 60%, 80%, and 90% but not 100% 1-RM (MPV: ICC =.66, CV = 18.0%, ES = 0.10, SEM = 0.04 m·s−1; MV: ICC =.55, CV = 19.4%, ES = 0.08, SEM = 0.04 m·s−1). When considering the reliable ranges, almost perfect correlations were observed for LVPs derived from PV20–100% (r =.91–.93), MPV20–90% (r =.92–.94), and MV20–90% (r =.94–.95). Furthermore, the LVPs were not significantly different (P >.05) between trials or movement velocities or between linear regression versus 2nd-order polynomial fits. Conclusions: PV20–100%, MPV20–90%, and MV20–90% are reliable and can be utilized to develop LVPs using linear regression. Conceptually, LVPs can be used to monitor changes in movement velocity and employed as a method for adjusting sessional training loads according to daily readiness. [ABSTRACT FROM AUTHOR]

Wilk, M, Krzysztofik, M, Filip, A, Zajac, A, Bogdanis, GC, and Lockie, RG. Short-term blood flow restriction increases power output and bar velocity during the bench press. J Strength Cond Res 36(8): 2082–2088, 2022—This study examined the effect of blood flow restriction (BFR) with 2 different types of cuffs on peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) in the bench press exercise (BP). Fourteen healthy strength-trained male athletes (age = 27.6 ± 3.5 years; body mass = 84.1 ± 8.0 kg; height = 175.8 ± 6.7 cm; BP 1 repetition maximum [RM] = 138.6 ± 17.8 kg) performed 3 different testing protocols as follows: without BFR (NO-BFR), BFR with a narrow cuff (BFRNARROW), and BFR with a wide cuff (BFRWIDE) in a randomized crossover design. During all sessions, subjects performed one set of 3 repetitions of the BP exercise using 70% 1RM. Cuff pressure was set to approximately 90% full arterial occlusion pressure of the upper limb at rest. Analyses of variance showed an increase in PP (by 21%, p < 0.01; effect size [ES] = 1.67), MP (by 16%, p < 0.01; ES = 0.93), PV (by 22%, p < 0.01; ES = 1.79), and MV (by 21%, p < 0.01; ES = 1.36) during BFRWIDE compared with NO-BFR and a significant increase in PP (by 15%, p < 0.01; ES = 1.07), MP (by 17%, p < 0.01; ES = 0.78), PV (by 18%, p < 0.01; ES = 1.65), and MV (by 13% p < 0.01; ES = 1.00) during BFRWIDE compared with BFRNARROW. There were no significant differences in any of the variable between NO-BFR and BFRNARROW. The results of the study indicate that short-term BFR training increases power output and bar velocity during the BP exercise. However, only BFRWIDE significantly influenced bar velocity and power output, which indicates that the width of the cuff is a critical factor determining acute exercise adaptation during BFR resistance training. [ABSTRACT FROM AUTHOR]

Merrigan, JJ and Martin, JR. Is the OUTPUT sports unit reliable and valid when estimating back squat and bench press concentric velocity? J Strength Cond Res 36(8): 2069–2076, 2022—This study evaluated the reliability and concurrent validity of the OUTPUT sports inertial unit to measure concentric velocity of free-weight back squat and bench press exercises. Eleven men and women performed back squat and bench press 1 repetition maximum (1RM) testing. One week later, subjects performed 3 repetitions of each exercise with 35, 45, 55, 65, 75, and 85% 1RM (18 total repetitions). The OUTPUT and 4 cable extension transducers (criterion) simultaneously recorded the mean and peak velocity. The OUTPUT had acceptable reliability for all loads except 85% 1RM for back squat and bench press (intraclass correlation coefficient = 0.72–0.96, coefficient of variation = 0.03–0.12). High systematic biases existed for the mean and peak velocity for the back squat and bench press, according to Bland-Altman plot's wide limits of agreement and ordinary least products regressions. According to Bland-Altman plots, OUTPUT tended to overestimate bench press velocity and overestimate back squat velocity at slower velocities. Least products regression analyses determined proportional bias existed for the mean and peak velocity of the back squat and peak velocity of the bench press. In conclusion, researchers and practitioners are advised not to compare velocity estimates of the OUTPUT unit with criterion devices because these methods cannot be used interchangeably. However, because of the demonstrated reliability when estimating the mean and peak velocity, strength and conditioning practitioners may find the OUTPUT unit valuable for monitoring performance of the back squat and bench press exercises. Yet, caution should be taken when evaluating loads ≥85% 1RM. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine the effects of coupling WBV and acute muscular fatigue to determine its effects on countermovement vertical jump (CMVJ) performance and isometric mid-thigh pull (IMTP). Twenty-eight healthy active adults volunteered for five-day study. Testing sessions 2–5 included one of four conditions: No WBV and no fatigue (CON), WBV and fatigue (WBV + FAT), WBV and no fatigue (WBV), and no WBV and fatigue (FAT). WBV was performed using a frequency of 50 Hz and a low amplitude while performing quarter squats for a total of 4 min with a 30 s rest or work ratio. Lower-body fatigue induced using Bosco fatigue protocol. CMVJ and IMTP were performed on force plates. SPSS was used to perform a 2 × 2 Repeated Measures ANOVA. Significant main effects were found for fatigue in CMVJ-height and CMVJ-peak ground reaction force, no significant main effect for WBV, and no significant interactions. Lower-body fatigue decreases vertical jump performance, and WBV did not attenuate the detrimental effects of lower-body fatigue.

Purpose: The purpose of this study was to evaluate the accuracy of four‐dimensional (4D) flow MRI for direct assessment of peak velocity, flow volume, and momentum of a mitral regurgitation (MR) flow jets using an in vitro pulsatile jet flow phantom. We systematically investigated the impact of spatial resolution and quantification location along the jet on flow quantities with Doppler ultrasound as a reference for peak velocity. Methods: Four‐dimensional flow MRI data of a pulsatile jet through a circular, elliptical, and 3D‐printed patient‐specific MR orifice model was acquired with varying spatial resolution (1.5–5 mm isotropic voxel). Flow rate and momentum of the jet were quantified at various axial distances (x = 0–50 mm) and integrated over time to calculate Voljet and MTIjet. In vivo assessment of Voljet and MTIjet was performed on 3 MR patients. Results: Peak velocities were comparable to Doppler ultrasound (3% error, 1.5 mm voxel), but underestimated with decreasing spatial resolution (−40% error, 5 mm voxel). Voljet was similar to regurgitant volume (RVol) within 5 mm, and then increased linearly with the axial distance (19%/cm) because of flow entrainment. MTIjet remained steady throughout the jet (2%/cm) as theoretically predicted. Four and 9 voxels across the jet were required to measure flow volume and momentum‐time‐integral within 10% error, respectively. Conclusion: Four‐dimensional flow MRI detected accurate peak velocity, flow rate, and momentum for in vitro MR‐mimicking flow jets. Spatial resolution significantly impacted flow quantitation, which otherwise followed predictions of flow entrainment and momentum conservation. This study provides important preliminary information for accurate in vivo MR assessment using 4D flow MRI. [ABSTRACT FROM AUTHOR]

IntroductionIn wheelchair rugby, players use either an offensive or defensive wheelchair depending on their field position and level of impairment. Performance of wheelchair rugby players is related to several parameters, however it is currently unclear if differences in performance are related to wheelchair type or no: the effect of wheelchair type on performance variables has not been evaluated. The aim of this study was to compare offensive and defensive wheelchairs on performance variables during a straight-line sprint.MethodsThirteen able-bodied people performed two 20 m sprint trials: one with an offensive and one with a defensive wheelchair. Data were collected using inertial measurement units fixed on the wheelchair. Peak wheelchair velocities and left-right asymmetries in peak wheel velocities were measured during the acceleration and constant peak velocity phases. Sprint time, cycle frequency, and mean and maximum velocity were calculated over the entire sprint.ResultsThe peak velocities of the first 2 pushes (acceleration phase) were significantly higher with the defensive than the offensive wheelchair (p < 0.04 and p < 0.02). Mean and maximum sprint velocity were significantly higher (p < 0.03 and p < 0.04, respectively) with the defensive wheelchair. Cycle frequency and asymmetry did not differ between wheelchairs.ConclusionPerformance was higher with the defensive than the offensive wheelchair, suggesting that the frequent finding that the higher performance of offensive as compared to defensive players is not related to the use of an offensive wheelchair.

In order to study the influence of different delay times on underground shallow hole blasting, numerical simulation software LS-DYNA was used to study the operation mode of underground shallow hole blasting with precise delay and hole-by-hole initiation. Based on the research status at home and abroad, five kinds of continuous uncoupled charged with different delay times of 15,20,25,30 and 35 ms were used for shallow-hole blasting. The field fine delay by hole initiation test was carried out. The blasting vibration velocity was collected by blasting vibration tester, and the velocity waveform was explored and analyzed. It was found that the vibration velocity peak at 25 ms with delay time decreased by 27%,8%,29% and 52% respectively, compared with the peak velocity at 15,20,30 and 35 ms. The research shows that the delay time is 25 ms, and the vibration reduction is the most pronounced. Reasonable delay time can effectively reduce the blasting vibration intensity and ensure the safety of surrounding rock masses. [ABSTRACT FROM AUTHOR]

Timing of puberty and adult height have opposing secular trends yet are positively associated in individuals. We demonstrate this using data from a single sample and discuss possible statistical and epidemiological reasons behind it. The sample comprised 365 females from Fels Longitudinal Study born 1929–1992. We used Super-Imposition by Translation and Rotation (SITAR) to estimate individual age at peak height velocity (PHV) and PHV from serial height data (8149 observations between 5 and 24 years). General linear regression was used to investigate the association between height and age at PHV, and secular trends in height, age at PHV and PHV. Although adult height increased 0.42 (95% CI: 0.08, 0.77) cm per decade, and age at PHV decreased 1.14 (−3.74, 1.45) weeks per decade, adult height increased by 2.44 (1.78, 3.10) cm per year higher age at PHV. We found tentative evidence of the positive association between age at PHV and adult height strengthened 0.25 (−0.09, 0.59) cm each decade. Secular trends in related variables may differ if the between-individual and between-cohort associations are different. To understand if a secular trend in one variable has contributed to a trend in another, each needs to be modelled over time, together with the changing association between them.

Background: In view of inconsistencies in threshold values of severe aortic stenosis (AS) hemodynamic indices, it is unclear what is the relative contribution of each variable in a binary classification of AS based on aortic valve replacement (AVR) indication. We aimed to assess relative discriminative value and optimal threshold of each constituent hemodynamic parameter for this classification and confirm additional prognostic value. Methods: Echocardiography studies of 168 patients with ≥ moderate AS were included. AS types were dichotomized into Group‐A, comprising moderate and Normal‐Flow Low‐Gradient (NFLG), and Group‐B, comprising High‐Gradient(HG), Low Ejection Fraction Low‐Flow Low‐Gradient(Low EF‐LFLG), and Paradoxical Low‐Flow Low‐Gradient(PLFLG) AS. Aortic valve area (AVA), Doppler velocity index (DVI), peak aortic velocity, mean gradient, stroke volume index and transaortic flow rate(TFR) were assessed for A/B Group discrimination value and optimal thresholds were determined. Dichotomized values were assessed for predictive value for AVR or death. Results: C‐statistic values for binary AS classification was.74–.9 for the tested variables. AVA and DVI featured the highest score, and SVI the lowest one. AVA≤.81 cm2 and DVI≤.249 had 87.6% and 86% respective sensitivity for Group B patients, and a similar specificity of 80.9%. During a mean follow‐up of 9.1±10.1 months, each of the tested dichotomized variables except for SVI predicted AVR or death on multivariate analysis. Conclusion: An AVA value ≤.81 cm2 or a DVI ≤.249 threshold carry the highest discriminative value for severe AS in patients with aortic stenosis, translating into an independent prognostic value, and can be helpful in making clinical decisions. [ABSTRACT FROM AUTHOR]

With the development of designed materials and structures, a wide array of micro/nanomachines with versatile functionalities are employed for specific sensing applications. Here, we demonstrated a magnetic propelled microdimer-based point-of-care testing system, which can be used to provide the real-time data of plasma glucose and lipids relying on the motion feedback of mechanical properties. On-demand and programmable speed and direction of the microdimers can be achieved with the judicious adjustment of the external magnetic field, while their velocity and instantaneous postures provide estimation of glucose, cholesterol, and triglycerides concentrations with high temporal accuracy. Numerical simulations reveal the relationship between motility performance and surrounding liquid properties. Such technology presents a point-of-care testing (POCT) approach to adapt to biofluid measurement, which advances the development of microrobotic system in biomedical fields.

Abstract Aims: The study aimed to evaluate the effects of a backward running (BR) training program prescribed by the peak backward running velocity (Vpeak_BR) on physiological variables and a 3 km forward running (FR) performance. Methods: Eight untrained running male adults in running took place in the study. All the participants underwent five weeks of BR training prescribed based on Vpeak_BR. They performed a maximal incremental test on the treadmill to determine the maximal oxygen uptake (V̇O2max) and the velocity associated with V̇O2max (vV̇O2max). The participants were also tested on the track field to determine the Vpeak_BR and undertook a 3 km FR performance. All initial assessments were also performed after the training period. Results: The results showed statistically significant improvements in 3 km FR performance (14.2 ± 1.2 min vs. 13.5 ± 1.0 min) and Vpeak_BR (8.0 ± 0.8 km·h−1 vs. 8.5 ± 0.5 km·h−1) after the training period. Conclusion: BR training effectively improved 3 km FR performance and Vpeak_BR, demonstrating that Vpeak_BR determined according to the protocol proposed in this study can be used for the prescription of BR training. Further, BR training represents an effective training method that can be inserted into an FR running training program.

• Analytically compared two approaches on the downstream variation of peak velocity. • Newly derived and evaluated a downstream hydraulic geometry relationships. • All the theoretical results were found to be well matched to those observed. • Especially, the downstream variation of peak velocity was found insignificant. This study compares three approaches to deriving the downstream hydraulic geometry (DHG) relationships: one by Leopold and Maddock (1953), a second by Huang and Nanson (2000), and the third in this study. The DHG relationships are the power function relationships between the downstream discharge and various variables, which include the flow velocity, channel width, channel depth, channel slope, and roughness coefficient. The DHG relationships can be described using a set of equations, including the continuity equation, flow velocity equation, and sediment transport equation. The derived relationships are then compared with the empirical results from previous studies worldwide, as well as those from two basins in Korea. As a result, first, all the theoretically derived exponents for peak velocity are found to be very small at around 0.1. This result supports the assumption that for a given rainfall event, the peak velocity in a basin remains unchanged. Simple regression analysis in this study also confirms that the change of peak flow velocity downstream is statistically insignificant. Through this, the assumption of a constant flow velocity within specific storm events may hold a certain degree of validity. Second, the range of the exponent for the channel width is found to be rather smaller at (0.4–0.6) than the those of the other two exponents. The range of the exponent for the channel depth is found to be (0.2–0.6), while that of the peak velocity to be (0.0–0.4). Possible reasons for this tendency have also been investigated in several studies, but have not yet been universally accepted. [ABSTRACT FROM AUTHOR]

The main goal of the present study was to evaluate the effects of different blood flow restriction (BFR) protocols (continuous and intermittent) on peak bar velocity (PV) and mean bar velocity (MV) during the squat exercise at progressive loads, from 40 to 90% 1RM. Eleven healthy men (age = 23.4 ± 3.1 years; body mass = 88.5 ± 12.1 kg; squat 1RM = 183.2 ± 30.7 kg; resistance training experience, 5.7 ± 3.6 years) performed experimental sessions once a week for 3 weeks in random and counterbalanced order: without BFR (NO-BFR), with intermittent BFR (I-BFR), and with continuous BFR (C-BFR). During the experimental session, the participants performed six sets of the barbell squat exercise with loads from 40 to 90% 1RM. In each set, they performed two repetitions. During the C-BFR session, the cuffs were maintained throughout the training session. During the I-BFR, the cuffs were used only during the exercise and released for each rest interval. The BFR pressure was set to ∼80% arterial occlusion pressure (AOP). Analyses of variance showed a statistically significant interaction for MV (p < 0.02; η2 = 0.18). However, the post hoc analysis did not show significant differences between particular conditions for particular loads. There was no significant condition × load interaction for PV (p = 0.16; η2 = 0.13). Furthermore, there were no main effects for conditions in MV (p = 0.38; η2 = 0.09) as well as in PV (p = 0.94; η2 = 0.01). The results indicate that the different BFR protocols used during lower body resistance exercises did not reduce peak bar velocity and mean bar velocity during the squat exercise performed with various loads.

The main goal of the present study was to evaluate the effects of different blood flow restriction (BFR) protocols (continuous and intermittent) on peak bar velocity (PV) and mean bar velocity (MV) during the squat exercise at progressive loads, from 40 to 90% 1RM. Eleven healthy men (age = 23.4 ± 3.1 years; body mass = 88.5 ± 12.1 kg; squat 1RM = 183.2 ± 30.7 kg; resistance training experience, 5.7 ± 3.6 years) performed experimental sessions once a week for 3 weeks in random and counterbalanced order: without BFR (NO-BFR), with intermittent BFR (I-BFR), and with continuous BFR (C-BFR). During the experimental session, the participants performed six sets of the barbell squat exercise with loads from 40 to 90% 1RM. In each set, they performed two repetitions. During the C-BFR session, the cuffs were maintained throughout the training session. During the I-BFR, the cuffs were used only during the exercise and released for each rest interval. The BFR pressure was set to ∼80% arterial occlusion pressure (AOP). Analyses of variance showed a statistically significant interaction for MV (p < 0.02; η2 = 0.18). However, the post hoc analysis did not show significant differences between particular conditions for particular loads. There was no significant condition × load interaction for PV (p = 0.16; η2 = 0.13). Furthermore, there were no main effects for conditions in MV (p = 0.38; η2 = 0.09) as well as in PV (p = 0.94; η2 = 0.01). The results indicate that the different BFR protocols used during lower body resistance exercises did not reduce peak bar velocity and mean bar velocity during the squat exercise performed with various loads. [ABSTRACT FROM AUTHOR]

We investigated whether using electrical muscle stimulation body massagers (EMS-BMs) for the passive contraction of the lower extremity muscles reduces venous stasis in the deep veins of the lower extremities. In this randomized crossover design study of 20 healthy volunteers between November 2018 and February 2019, we measured both the popliteal and femoral vein peak velocities (PV, cm/s) and blood flow volumes (BFV,mL/min), using pulsed-wave Doppler ultrasound at rest (baseline), and at 2 and 10 min after starting EMS-BM use. Two EMS types: types A (two small pads) and B (one large pad) devices respectively, were examined. The PVs of the femoral (A: 23±7, B: 25±8) and popliteal (A: 26±12, B: 27±12) veins and BFV of types A (107±46) and B (141±88) of the femoral vein were significantly increased compared to the baseline (PV of femoral vein: 19±9, PV of popliteal vein: 14±5, BFV of popliteal vein: 81±46) (P <0.01). No significant differences occurred between the devices in the PV or BFV at either 2 or 10 min. Regardless of the type of stimulation or the shape of the pad, contraction of the lower limb muscles by EMS-BM effectively reduces venous stasis in the lower limb. [ABSTRACT FROM AUTHOR]

Based on the in-situ expansion project of Jinjishan tunnel in Fuzhou 2nd ring road, the row-hole blasting was simplified to the triangular blast load and then applied upon the centerline of row-hole according to the detonator time-interval. The whole process of millisecond blast in the left head face of left tunnel was carefully studied by the refined numerical simulation, and the blast-induced vibration effect upon the surrounding tunnels was well focused. As far as pedestrian tunnel was concerned, the peak velocity of frontward side was 5 ~ 13 times to its counterpart of backward side, and the vertical-direction peak velocity at the frontward side wall reached to 4.55 cm/s. On the other hand, the vibration effect of right tunnel was negligible, since the existing cavity within left tunnel could hamper the propagation of vibration wave significantly. The field monitoring at the frontward side wall was also carried out, whose three-dimensional velocity histories generally coincided with the results from numerical simulation. The time-interval among peaks coincided with the delay of detonators, while the peak velocity was 10％~30％ greater than its counterpart calculated by numerical simulation. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of continuous and intermittent blood flow restriction (BFR) with 70% of full arterial occlusion pressure on bar velocity during the bench press exercise against a wide range of resistive loads. Eleven strength-trained males (age: 23.5 ± 1.4 years; resistance training experience: 2.8 ± 0.8 years, maximal bench press strength – 1RM = 101.8 ± 13.9 kg; body mass = 79.8 ± 10.4 kg), performed three different testing protocols in random and counterbalanced order: without BFR (NO-BFR); intermittent BFR (I-BFR) and continuous BFR (C-BFR). During each experimental session, subjects performed eight sets of two repetitions each, with increasing loads from 20 to 90% 1RM (10% steps), and 3 min rest between each set. In the C-BFR condition occlusion was kept throughout the trial, while in the I-BFR, occlusion was released during each 3 min rest interval. Peak bar velocity (PV) during the bench press exercise was higher by 12–17% in both I-BFR and C-BFR compared with NO-BFR only at the loads of 20, 30, 40, and 50% 1RM (p < 0.001), while performance at higher loads remained unchanged. Mean bar velocity (MV) was unaffected by occlusion (p = 0.342). These results indicate that BFR during bench press exercise increases PV and this may be used as an enhanced stimulus during explosive resistance training. At higher workloads, bench press performance was not negatively affected by BFR, indicating that the benefits of exercise under occlusion can be obtained while explosive performance is not impaired.

The aim of this paper is to study the soil vibration response of a pile group induced by train traffic resting on the inclined bedrock condition. A series of model tests on the response of peak velocity were conducted in terms of inclined bedrock, loading frequency and short/long piles. The experimental results show that the peak velocity increased from the upslope to the downslope direction along the soil surface affected by the bedrock. The peak velocity increased with the increasing of loading frequency. In addition, as the loading frequency and horizontal distance increased, the difference of peak velocity along the circular direction in the soil surface would be more significant. The combined effects of long and short piles would induce a large difference of peak velocity on the pile side. However, the peak velocity on the concrete slab would not be affected. Furthermore, the peak velocity at the central point of the pile group was nearly the same to that on the side of the long pile and two times larger than that on the side of the short pile, which indicates the superposition of vibration wave of the pile group. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of continuous and intermittent blood flow restriction (BFR) with 70% of full arterial occlusion pressure on bar velocity during the bench press exercise against a wide range of resistive loads. Eleven strength-trained males (age: 23.5 ± 1.4 years; resistance training experience: 2.8 ± 0.8 years, maximal bench press strength – 1RM = 101.8 ± 13.9 kg; body mass = 79.8 ± 10.4 kg), performed three different testing protocols in random and counterbalanced order: without BFR (NO-BFR); intermittent BFR (I-BFR) and continuous BFR (C-BFR). During each experimental session, subjects performed eight sets of two repetitions each, with increasing loads from 20 to 90% 1RM (10% steps), and 3 min rest between each set. In the C-BFR condition occlusion was kept throughout the trial, while in the I-BFR, occlusion was released during each 3 min rest interval. Peak bar velocity (PV) during the bench press exercise was higher by 12–17% in both I-BFR and C-BFR compared with NO-BFR only at the loads of 20, 30, 40, and 50% 1RM (p < 0.001), while performance at higher loads remained unchanged. Mean bar velocity (MV) was unaffected by occlusion (p = 0.342). These results indicate that BFR during bench press exercise increases PV and this may be used as an enhanced stimulus during explosive resistance training. At higher workloads, bench press performance was not negatively affected by BFR, indicating that the benefits of exercise under occlusion can be obtained while explosive performance is not impaired. [ABSTRACT FROM AUTHOR]

Timing of puberty and adult height have opposing secular trends yet are positively associated in individuals. We demonstrate this using data from a single sample and discuss possible statistical and epidemiological reasons behind it. The sample comprised 365 females from Fels Longitudinal Study born 1929–1992. We used Super-Imposition by Translation and Rotation (SITAR) to estimate individual age at peak height velocity (PHV) and PHV from serial height data (8149 observations between 5 and 24 years). General linear regression was used to investigate the association between height and age at PHV, and secular trends in height, age at PHV and PHV. Although adult height increased 0.42 (95% CI: 0.08, 0.77) cm per decade, and age at PHV decreased 1.14 (−3.74, 1.45) weeks per decade, adult height increased by 2.44 (1.78, 3.10) cm per year higher age at PHV. We found tentative evidence of the positive association between age at PHV and adult height strengthened 0.25 (−0.09, 0.59) cm each decade. Secular trends in related variables may differ if the between-individual and between-cohort associations are different. To understand if a secular trend in one variable has contributed to a trend in another, each needs to be modelled over time, together with the changing association between them. [ABSTRACT FROM AUTHOR]

Economy of effort, a popular notion in contemporary speech research, predicts that dynamic extremes such as the maximum speed of articulatory movement are avoided as much as possible and that approaching the dynamic extremes is necessary only when there is a need to enhance linguistic contrast, as in the case of stress or clear speech. Empirical data, however, do not always support these predictions. In the present study, we considered an alternative principle: maximum rate of information, which assumes that speech dynamics are ultimately driven by the pressure to transmit information as quickly and accurately as possible. For empirical data, we asked speakers of American English to produce repetitive syllable sequences such as wawawawawa as fast as possible by imitating recordings of the same sequences that had been artificially accelerated and to produce meaningful sentences containing the same syllables at normal and fast speaking rates. Analysis of formant trajectories shows that dynamic extremes in meaningful speech sometimes even exceeded those in the nonsense syllable sequences but that this happened more often in unstressed syllables than in stressed syllables. We then used a target approximation model based on a mass-spring system of varying orders to simulate the formant kinematics. The results show that the kind of formant kinematics found in the present study and in previous studies can only be generated by a dynamical system operating with maximal muscular force under strong time pressure and that the dynamics of this operation may hold the solution to the long-standing enigma of greater stiffness in unstressed than in stressed syllables. We conclude, therefore, that maximum rate of information can coherently explain both current and previous empirical data and could therefore be a fundamental principle of motor control in speech production.