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  • Author: Serge S. Colson x
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Fabrice Vercruyssen, Mathieu Gruet, Serge S. Colson, Sabine Ehrstrom and Jeanick Brisswalter

Background:

Physiological mechanisms behind the use of compression garments (CGs) during off-road running are unknown.

Purpose:

To investigate the influence of wearing CGs vs conventional running clothing (CON) on muscle contractile function and running economy before and after short-distance trail running.

Methods:

Knee-extensor neuromuscular function and running economy assessed from two 5-min treadmill runs (11 and 14 km/h) were evaluated before and after an 18.6-km short-distance trail run in 12 trained athletes wearing either CGs (stocking + short-tight) or CON. Quadriceps neuromuscular function was assessed from mechanical and EMG recording after maximal percutaneous electrical femoral-nerve stimulations (single-twitch doublets at 10 [Db10] and 100 Hz [Db100] delivered at rest and during maximal quadriceps voluntary contraction [MVC]).

Results:

Running economy (in mL O2 · km–1 · kg–1) increased after trail running independent of the clothing condition and treadmill speeds (P < .001). Similarly, MVC decreased after CON and CGs conditions (–11% and –13%, respectively, P < .001). For both clothing conditions, a significant decrease in quadriceps voluntary activation, Db10, Db100, and the low-to-high frequency doublet ratio were observed after trail running (time effect, all P < .01), without any changes in rectus femoris maximal M-wave.

Conclusions:

Wearing CGs does not reduce physiological alterations induced during short-distance trail running. Further studies should determine whether higher intensity of compression pressure during exercises of longer duration may be effective to induce any physiological benefits in experienced trail runners.

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Jérôme Vaulerin, Frédéric Chorin, Mélanie Emile, Fabienne d’Arripe-Longueville and Serge S. Colson

Context: Firefighters participating in mandatory physical exercise sessions are exposed to a high risk of ankle sprain injury. Although both physiological and psychological risk factors have been identified, few prospective studies considered the complex interaction of these factors in firefighters. Objective: To prospectively determine whether intrinsic physical risk factors and work-related environments predict ankle sprains occurring during on-duty physical exercise in firefighters during an 8-month follow-up period. Design: Prospective. Setting: Fire Department and Rescue Service. Participants: Thirty-nine firefighters were selected based on convenience sampling. Intervention: Participants performed physical tests and completed questionnaires. Main Outcome Measures: Lower Quarter Y-Balance Test, Weight-Bearing Lunge Test, anthropometric measures, postural stability, chronic ankle instability (Cumberland Ankle Instability Tool) scores, previous injuries, and perceived psychosocial work environment (Copenhagen Psychosocial Questionnaire [COPSOQ]). Results: During the follow-up, 9 firefighters sustained an injury. Lower Quarter Y-Balance Test and Weight-Bearing Lunge Test performances, Cumberland Ankle Instability Tool scores, history of previous ankle sprain, and specific dimensions of the COPSOQ significantly differed between injured and uninjured firefighters. Lower-limbs asymmetries of the Lower Quarter Y-Balance Test (ie, anterior, posteromedial, and posterolateral directions) and the Weight-Bearing Lunge Test were predictors of ankle sprains. Conclusions: These findings originally provide evidence that intrinsic factors mainly contribute to ankle sprains, although psychosocial work environment assessment could also characterize firefighters at risk.

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Olivier Seynnes, Olivier A. Hue, Frédéric Garrandes, Serge S. Colson, Pierre L. Bernard, Patrick Legros and Maria A. Fiatarone Singh

The relationship between isometric force control and functional performance is unknown. Submaximal steadiness and accuracy were measured during a constant force-matching task at 50% of maximal isometric voluntary contraction (MVC) of the knee extensors in 19 older women (70–89 years). Other variables included MVC, rate of torque development, and EMG activity. Functional performance was assessed during maximal performance of walking endurance, chair rising, and stair climbing. Isometric steadiness (but not accuracy) was found to independently predict chair-rise time and stair-climbing power and explained more variance in these tasks than any other variable. Walking endurance was related to muscle strength but not steadiness. These results suggest that steadiness is an independent predictor of brief, stressful functional-performance tasks in older women with mild functional impairment. Thus, improving steadiness might help reduce functional limitations or disability in older adults.