Ankle and Plantar Flexor Muscle-Tendon Unit Function in Sprinters: A Narrative Review.

Maximal sprinting in humans requires the contribution of various muscle-tendon units (MTUs) and joints to maximize performance. The plantar flexor MTU and ankle joint are of particular importance due to their role in applying force to the ground. This narrative review examines the contribution of the ankle joint and plantar flexor MTUs across the phases of sprinting (start, acceleration, and maximum velocity), alongside the musculotendinous properties that contribute to improved plantar flexor MTU performance.

Neuromuscular Plantar Flexor Performance of Sprinters versus Physically Active Individuals.

Introduction: Comparison of the neuromuscular performance of different athlete types may give insight into the in vivo variability of these measures and their underpinning mechanisms. The study aims to compare the neuromuscular function of the plantar flexors of sprinters and physically active individuals to assess any differences in explosive force performance.

Methods: Neuromuscular performance of a group of sprinters (highly trained/national level, n = 12; elite/international level, n = 2) and physically active individuals ( n = 14) were assessed during involuntary, explosive, and maximum voluntary isometric plantar flexions, across different muscle-tendon unit (MTU) lengths (10° plantarflexion, 0° (anatomical zero/neutral), and 10° dorsiflexion).

Reliability of mechanical properties of the plantar flexor muscle tendon unit with consideration to joint angle and sex.

The reliability of mechanical measures can be impacted by the protocol used, including factors such as joint angle and the sex of participants. This study aimed to determine the inter-day reliability of plantar flexor mechanical measures across ankle joint angles and contraction types and consider potential sex-specific effects. 14 physically-active individuals participated in two identical measurement sessions involving involuntary and voluntary plantar flexor contractions, at three ankle angles (10° plantarflexion (PF), 0° (anatomical zero (AZ)), and 10° dorsiflexion (DF)), while torque and surface EMG were recorded.

Effect of Changing Match Format from Halves to Quarters on the Performance Characteristics of Male University Field Hockey Players.

The study examined whether the performance characteristics of male university field hockey players differed when the match format was 2 × 35 min halves compared to 2 × 2 × 17.5 min quarters. Thirty-five male university field hockey players (age 21.

Sources of Error When Measuring Achilles Tendon Mechanics During the Stance Phase of Running.

In recent years, the use of methods to investigate muscle-tendon unit function that combine motion capture with ultrasound (MoCapUS) has increased. Although several limitations and individual errors of these methods have been reported, the total error from all the potential sources together has not been estimated. The aim of this study was to establish the total error in the Achilles tendon (AT) measurements, specifically its length (ATL), strain (ATS), and moment arm (ATMA) acquired with MoCapUS during running.

Onset detection in surface electromyographic signals across isometric explosive and ramped contractions: a comparison of computer-based methods.

. Accurate identification of surface electromyography (EMG) muscle onset is vital when examining short temporal parameters such as electromechanical delay. The visual method is considered the 'gold standard' in onset detection.

Measurement of instantaneous Achilles tendon moment arm and force during the stance phase of running.

Accurate estimates of the Achilles tendon (AT) moment arm (AT) are necessary for investigating triceps surae muscle-tendon unit loading and function. There are limited reported values of AT during running. By combining ultrasound and motion capture, AT was estimated during the stance phase of running.

Changes in inertial parameters of the lower limb during the impact phase of dynamic tasks.

Mechanical analysis at the whole human body level typically assumes limbs are rigid bodies with fixed inertial parameters, however, as the human body consists mainly of deformable soft tissue, this is not the case. The aim of this study was to investigate changes in the inertial parameters of the lower limb during landing and stamping tasks using high frequency three-dimensional motion analysis. Seven males performed active and passive drop landings from 30 and 45 cm and a stamp onto a force plate.

Measuring muscle size and symmetry in healthy adult males using a time-efficient analysis of magnetic resonance images.

Objective: Muscle volume (MV) analysis from magnetic resonance imaging (MRI) is time-intensive, and limited measurement reliability data are available. This study investigated a method to reduce lower limb MV analysis time demands, established reliability of these measurements, and applied the findings to quantify muscle size and symmetry in healthy adult males.

Approach: Bilateral MRI images were acquired from 15 healthy males (age: 26.

Measures of Strength and Jump Performance Can Predict 30-m Sprint Time in Rugby Union Players.

Furlong, L-AM, Harrison, AJ, and Jensen, RL. Measures of strength and jump performance can predict 30-m sprint time in Rugby Union players. J Strength Cond Res 35(9): 2579-2583, 2021-Performance and fitness monitoring in Rugby Union often include jumping, sprinting, and strength tests, but repeatability of and relationships between these measures are unclear.

The Internationalization of National Biomechanics Day.

National Biomechanics Day (NBD) was initiated in 2016 as a nation-wide effort to introduce Biomechanics to high school students throughout the United States. After that initial year, many people around the world joined NBD to promote Biomechanics in their own countries. National Biomechanics Day became international.

Does the McNeill Alexander model accurately predict maximum walking speed in novice and experienced race walkers?

Background: Mathematical models propose leg length as a limiting factor in determining the maximum walking velocity. This study evaluated the effectiveness of a leg length-based model in predicting maximum walking velocity in an applied race walking situation, by comparing experienced and novice race walkers during conditions where strictly no flight time (FT) was permitted and in simulated competition conditions (i.e.

Injury incidence in elite youth field hockey players at the 2016 European Championships.

Despite being an essential consideration when deciding rule changes, injury prevention strategies, and athlete development models, there is little epidemiological data of U18 field hockey player injuries-something explicitly referred to in the 2015 International Olympic Committee's Consensus Statement on Youth Athlete Development. The aim of this study was to quantify incidence and characteristics of injuries in elite youth field hockey players during a major international tournament. Standardized reporting forms detailing time, location on pitch, mechanism and anatomical location of injury were completed for new musculoskeletal conditions resulting in a time stoppage by the umpire and where a player was noticeably affected by an injury for up to 20 s regardless of time stoppage.

Kinetic Asymmetry during Running at Preferred and Nonpreferred Speeds.

Purpose: The aim of this study was to investigate the effect of altering preferred running speed by ±20% on kinetic asymmetry.

Methods: Three-dimensional motion analysis and force data were acquired from 15 healthy males (age, 27 ± 4.6 yr; height, 1.

Differences in plantarflexor function during a stretch-shortening cycle task due to limb preference.

Most healthy humans move symmetrically at gross limb level but large kinetic and kinematic asymmetries have been observed at joint level during locomotion. The aim of this study was to assess muscle function asymmetries in healthy, active adults using an adapted force sledge apparatus which isolates the plantarflexors during a stretch-shortening cycle (SSC) task. Peak force, rate of force development and SSC function of preferred and non-preferred limbs were assessed in 21 healthy, active individuals using the adapted sledge and three-dimensional motion analysis.

A motion analysis marker-based method of determining centre of pressure during two-legged hopping.

The fixed position of force plates has led researchers to pursue alternative methods of determining centre of pressure (CoP) location. To date, errors reported using alternative methods to the force plate during dynamic tasks have been high. The aim of this study was to investigate the accuracy of a motion analysis marker-based system to determine CoP during a two-legged hopping task.

Reliability and consistency of plantarflexor stretch-shortening cycle function using an adapted force sledge apparatus.

There are various limitations to existing methods of studying plantarflexor stretch-shortening cycle (SSC) function and muscle-tendon unit (MTU) mechanics, predominantly related to measurement validity and reliability. This study utilizes an innovative adaptation to a force sledge which isolates the plantarflexors and ankle for analysis. The aim of this study was to determine the sledge loading protocol to be used, most appropriate method of data analysis and measurement reliability in a group of healthy, non-injured subjects.