Search results for "229"
showing 10 items of 1572 documents
Running in highly cushioned shoes increases leg stiffness and amplifies impact loading
2018
AbstractRunning shoe cushioning has become a standard method for managing impact loading and consequent injuries due to running. However, despite decades of shoe technology developments and the fact that shoes have become increasingly cushioned, aimed to ease the impact on runners’ legs, running injuries have not decreased. To better understand the shoe cushioning paradox, we examined impact loading and the spring-like mechanics of running in a conventional control running shoe and a highly cushioned maximalist shoe at two training speeds, 10 and 14.5 km/h. We found that highly cushioned maximalist shoes alter spring-like running mechanics and amplify rather than attenuate impact loading. T…
Associations of Physical Fitness and Body Composition Characteristics With Simulated Military Task Performance
2017
Pihlainen, K, Santtila, M, Hakkinen, K, and Kyrolainen, H. Associations of physical fitness and body composition characteristics with simulated military task performance. J Strength Cond Res 32(4): 1089-1098, 2018-The purpose of this study was to evaluate the associations of physical fitness and body composition characteristics with anaerobic endurance performance, tested in the combat load using the occupationally relevant military simulation test (MST). Eighty-one male soldiers, deployed to a crisis management operation in the Middle East, volunteered for the study and participated in a test battery consisting measurements of muscle strength, body composition characteristics, endurance ca…
Motor Development and Physical Activity: A Longitudinal Discordant Twin-Pair Study.
2015
ntroduction : Previous longitudinal research suggests that motor proficiency in early life predicts physical activity in adulthood. Familial effects including genetic and environmental factors could explain the association, but no long-term follow-up studies have taken into account potential confounding by genetic and social family background. The present twin study investigated whether childhood motor skill development is associated with leisure-time physical activity levels in adulthood independent of family background. Methods : Altogether, 1550 twin pairs from the FinnTwin12 study and 1752 twin pairs from the FinnTwin16 study were included in the analysis. Childhood motor development wa…
Conditioning hops increase triceps surae muscle force and Achilles tendon strain energy in the stretch-shortening cycle
2018
Postactivation potentiation can improve athletic performance, but the underlying mechanisms are poorly understood. This study investigated the effect of conditioning hops on triceps surae muscle force and tendon strain and its contribution to potentiated stretch-shortening cycle (SSC) performance. Thirty-two subjects participated in two experiments. In both experiments, subjects performed three drop jumps (DJs) after prior conditioning with 10 maximal hops, three unconditioned DJs served as control. Ground reaction forces, kinematics, and triceps surae electromyographic activity were recorded. Ultrasound imaging was used to determine fascicle lengths (FASC) of the gastrocnemius (GM) and sol…
Mechanical and neural function of triceps surae in elite racewalking
2016
Racewalking is a unique event combining mechanical elements of walking with speeds associated with running. It is currently unclear how racewalking technique impacts upon lower limb muscle-tendon function, despite the relevance of this to muscle economy and overall performance. The present study examined triceps surae neuromechanics in 11 internationally competitive racewalkers (age 25±11 years) walking and running on a treadmill at speeds between 4.5 - 13.8 km/h whilst triceps surae fascicle lengths, electromyography and kinematic data were recorded. Cumulative muscle activity required to traverse a unit distance (CMAPD) was calculated for each muscle. Medial gastrocnemius (MG) and soleus …
Genetic and Environmental Effects on the Individual Variation and Continuity of Participation in Diverse Physical Activities
2021
INTRODUCTION Participation in diverse physical activities has beneficial health effects. However, little is known on how genetic and environmental factors affect this trait. Thus, we examined to what extent these factors explain participation in diverse leisure-time physical activities from late adolescence to adulthood using a twin study design. METHODS The participants were Finnish twins who reported their participation in diverse leisure-time physical activities at ages 17 (n = 5429) and 34 yr (n = 4246). The number of physical activities engaged in was analyzed using applications of structural linear modeling for twin data. RESULTS On average, the total number of physical activities eng…
Tracking the corticospinal responses to strength training
2020
Purpose\ud The motor cortex (M1) appears to be a primary site of adaptation following both a single session, and repeated strength-training sessions across multiple weeks. Given that a single session of strength-training is sufficient to induce modification at the level of the M1 and corticospinal tract, this study sought to determine how these acute changes in M1 and corticospinal tract might accumulate across the course of a 2-week heavy-load strength-training program.\ud \ud Methods\ud Transcranial magnetic stimulation (TMS) was used to infer corticospinal excitability (CSE), intracortical facilitation (ICF), short and long-interval intracortical inhibition (SICI and LICI) and silent per…
Postactivation potentiation can counteract declines in force and power that occur after stretching.
2016
Stretching can decrease a muscle's maximal force, whereas short but intense muscle contractions can increase it. We hypothesized that when combined, postactivation potentiation induced by reactive jumps would counteract stretch-induced decrements in drop jump (DJ) performance. Moreover, we measured changes in muscle twitch forces and ankle joint stiffness (KAnkle ) to examine underlying mechanisms. Twenty subjects completed three DJs and 10 electrically evoked muscle twitches of the triceps surae subsequent to four different conditioning activities and control. The conditioning activities were 10 hops, 20s of static stretching of the triceps surae muscle, 20s of stretching followed by 10 ho…
Cardiorespiratory Changes During Prolonged Downhill Versus Uphill Treadmill Exercise
2020
AbstractOxygen uptake (V̇O2), heart rate (HR), energy cost (EC) and oxygen pulse are lower during downhill compared to level or uphill locomotion. However, a change in oxygen pulse and EC during prolonged grade exercise is not well documented. This study investigated changes in cardiorespiratory responses and EC during 45-min grade exercises. Nine male healthy volunteers randomly ran at 75% HR reserve during 45-min exercise in a level (+1%), uphill (+15%) or downhill (−15%) condition. V̇O2 , minute ventilation (V̇E ) and end-tidal carbon dioxide (PetCO2) were recorded continuously with 5-min averaging between the 10th and 15th min (T1) and 40th and 45th min (T2). For a similar HR (157±3 bpm…
Changes in biomechanics of skiing at maximal velocity caused by simulated 20 km skiing race using V2 skating technique
2017
This study investigated how the fatigue caused by a 20 km simulated skating cross-country skiing race on snow affects the final spurt performance from a biomechanical perspective. Subjects performed a 100 meter maximal skiing trial before and at the end of the simulated race. Cycle characteristics, ground reaction forces from skis and poles, and muscle activity from eight muscles were recorded during each trial. Results showed that subjects were in a fatigued state after the simulated race manifested by 11.6% lower skiing speed (P < 0.01). The lower skiing speed was related to an 8.0% decrease in cycle rate (P < 0.01) whereas cycle length was slightly decreased (tendency). In temporal patte…