Causes of Different Force-Velocity Relationships in Sprint Running Depending on Horizontal Loads and Profiling Methods.

Purpose: We aimed to clarify how the horizontal force-velocity (Fvh) relationship during over-ground sprint running differs with horizontal resistance loads and profiling methods (multiple- and single-trial methods).

Methods: Twelve males performed sprint running (one unresisted and five resisted) using a motorized loading device. During the trials, the ground reaction forces at every step were obtained using a 50 m force plate system.

Revamping Pace Distribution: A Case Study on Elevating the Men's 400 m Track and Field Japanese National Record After 32 Years.

Chiba, Y, Sato, K, Yoshimoto, T, Ohnuma, H, Yamanaka, R, Takahashi, K, Kobayashi, K, Matsubayashi, T, and Takai, Y. Revamping pace distribution: A case study on elevating the men's 400 m track and field Japanese national record after 32 years. J Strength Cond Res XX(X): 000-000, 2024-Many studies have investigated the 400-m sprint, and the optimal pacing strategy is subject to debate.

Resistance training leading to repetition failure increases muscle strength and size, but not power-generation capacity in judo athletes.

Strength-trained athletes has less trainability in muscle size and function, because of their adaptation to long-term advanced training. This study examined whether resistance training (RT) leading to repetition failure can be effective modality to overcome this subject. Twenty-three male judo athletes completed a 6-week unilateral dumbbell curl training with two sessions per week, being added to in-season training of judo.

Validity of spatiotemporal and ground reaction force estimates during resisted sprinting with a motorized loading device.

We aimed to examine the validity of estimating spatiotemporal and ground reaction force (GRF) parameters during resisted sprinting using a robotic loading device (1080 Sprint). Twelve male athletes (age: 20.9 ± 2.

Effects of Different Isometric Training Programs on Muscle Size and Function in the Elbow Flexors.

It remains unknown whether a regimen of a combination of high- and low-intensity resistance training increases muscle size and maximal voluntary isometric contraction (MVC) simultaneously. This study aimed to clarify the effect of the combination of high- and low-intensity resistance training on muscle size and neuromuscular function in the elbow flexors. Sixteen male adults participated in a 9-week isometric training regimen in elbow joint flexion of each arm.

Differences between junior and senior male sprinters in physiological variables associated with sprint performance.

Background: The physiological variables associated with sprint performance have been extensively studied. However, little information is available on how the corresponding physiological variables differ between junior and senior sprinters. This study aimed to examine this subject.

Comparison of available equations to estimate sit-to-stand muscle power and their association with gait speed and frailty in older people: Practical applications for the 5-rep sit-to-stand test.

Objectives: This study aimed i) to compare relative sit-to-stand power (STS) values yielded by the different equations reported in the literature; ii) to examine the associations between STS, derived from the equations, and age, sex, frailty and habitual gait speed (HGS); and iii) to compare the ability of the different STS equations to detect frailty and low HGS in older adults.

Methods: 1568 participants (>65 years) were included. STS was calculated according to four validated equations.

A new approach to quantify angles and time of changes-of-direction during soccer matches.

Background And Aims: Soccer players frequently perform change-of-directions (CODs) at various speeds during matches. However, tracking systems have shown limitations to measure these efforts. Therefore, the aim of the present study was to propose a new approach to measure CODs using a local positioning system (LPS), and clarify position-related difference in profile of CODs by using the approach.

Force-velocity relationship profile of elbow flexors in male gymnasts.

Background: The theoretical maximum force (F), velocity (V), and power (P) of athletes calculated from the relationship between force and velocity (F-V relationship) and the slope of the F-V relationship, reflect their competitive and training activity profiles. Evaluating the F-V relationship of athletes facilitates categorizing the profiles of dynamic muscle functions in relation to long-term sport-specific training. For gymnastics, however, no studies have tried to examine the profiles of F-V relation and power output for upper limb muscles in relation to the muscularity, while the use of the upper extremities in this sport is very unique as described earlier.

The effect of biological maturity status on ground reaction force production during sprinting.

Sprint ability develops nonlinearly across childhood and adolescence. However, the underpinning ground reaction force (GRF) production is not fully understood. This study aimed to uncover the kinetic factors that explain these maturation-related sprint performance differences in Japanese boys and girls.

Profile of regional fat and fat-free soft tissue accumulation in male athletes.

Background: It is unclear whether or not the breakpoint (BP), at which the proportion of each of fat mass (FM) and fat-free soft tissue mass (FFSTM) to body mass (BM) alter, exists in male athletes. We examined the hypothesis that in male athletes, the regional FM and FFSTM-BM relationships have a BP, but the body mass at BP (BM) differs among the arms, trunk, and legs.

Methods: By using a dual X-ray absorptiometry, whole-body and regional FMs and FFSTMs in the arms, trunk, and legs were estimated in 198 male athletes (20.

Ten-second maximal pedaling power as a representative measure for assessing sprint performance.

Background: There is no evidences concerning the relative contribution of physiological parameters to maximal sprinting velocity and acceleration ability. The aim of this study is to elucidate the associations between physiological variables and sprint performance.

Methods: Twenty-six male sprinters performed a 60-m sprint twice.

Age-related differences in kinematics and kinetics of sprinting in young female.

This study aimed to investigate the age-related differences in sprinting performance, kinematic and kinetic variables in girls aged between 7.0 and 15.3 years.

Spatiotemporal and Kinetic Determinants of Sprint Acceleration Performance in Soccer Players.

We aimed to elucidate spatiotemporal and kinetic determinants of sprint acceleration performance in soccer players. Thirty-seven male soccer players performed 60-m sprints. The spatiotemporal variables and ground reaction impulses were calculated over a 50-m distance.

How sprinters accelerate beyond the velocity plateau of soccer players: Waveform analysis of ground reaction forces.

Forces applied to the ground during sprinting are vital to performance. This study aimed to understand how specific aspects of ground reaction force waveforms allow some individuals to continue to accelerate beyond the velocity plateau of others. Twenty-eight male sprint specialists and 24 male soccer players performed maximal-effort 60-m sprints.

Age-Related Differences in Spatiotemporal Variables and Ground Reaction Forces During Sprinting in Boys.

Purpose: We aimed to elucidate age-related differences in spatiotemporal and ground reaction force variables during sprinting in boys over a broad range of chronological ages.

Methods: Ground reaction force signals during 50-m sprinting were recorded in 99 boys aged 6.5-15.

Vertical Impulse as a Determinant of Combination of Step Length and Frequency During Sprinting.

This study aimed to clarify the influence of vertical impulse on the magnitude of step length (SL) and frequency (SF) and their ratio during the entire acceleration phase of maximal sprinting. Thirty-nine male soccer players performed 60-m sprints, during which step-to-step ground reaction forces were recorded over a 50-m distance. The mean values of spatiotemporal variables and vertical and anteroposterior impulses for each set of four steps during the acceleration phase until the 28th step were computed to examine relationships among variables in seven sections.

Body shape indices are predictors for estimating fat-free mass in male athletes.

It is unknown whether body size and body shape parameters can be predictors for estimating whole body fat-free mass (FFM) in male athletes. This study aimed to investigate whether body size and shape variables can be predictors for FFM in male athletes. Using a whole-body dual-energy X-ray absorptiometry scanner, whole body fat mass (FM) and FFM were determined in 132 male athletes and 14 sedentary males.

Cardiorespiratory and metabolic responses to body mass-based squat exercise in young men.

Background: The purpose of this study was to quantify cardiorespiratory and metabolic responses to body mass-based squat exercise, with specific emphasis on the relationships with the exercise duration.

Methods: Fifteen healthy young men performed body mass-based squat exercise as well as an incremental loaded bicycle test, which determine maximal oxygen uptake and maximal heart rate, with an interval of 2 days between the tests. During both tasks, oxygen uptake, blood lactate concentration (BLa), and heart rate (HR) were determined.

Validity of muscle thickness-based prediction equation for quadriceps femoris volume in middle-aged and older men and women.

Background: This study examined the validity of muscle thickness (MT)-based prediction equation for the muscle volume of the quadriceps femoris (QFMV) by evaluating the applicability of a prediction equation previously derived from young men and by developing a new prediction equation in middle-aged and older individuals.

Methods: The MT at the midpoint of the thigh anterior and QFMV were determined using ultrasonography and magnetic resonance imaging in 30 men and 30 women aged 51 to 77 years. First, we examined the validity of the MT-based prediction equation previously developed for young men to estimate the QFMV of middle-aged and older individuals.

The relationship between childhood aerobic fitness and brain functional connectivity.

Several studies have indicated that higher levels of childhood aerobic fitness is associated with superior cognitive function, and this association is disproportionately observed in tasks requiring greater top-down control. We designed the current study to clarify the relationship between childhood fitness and top-down control in terms of functional connectivity among brain regions, by evaluating phase-locking values (PLVs), which is a measure of frequency-specific phase synchrony between electroencephalographic signals during a visual search task. Lower-fit and higher-fit children performed a visual search task that included feature search and conjunction search conditions.

Acute effects of different conditioning activities on running performance of sprinters.

This study investigated acute effects of different conditioning activities on sprint performance of collegiate sprinters using a randomized, crossover design. Male sprinters (N = 10; 20.1 ± 0.