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After a unilateral muscle exercise, the performance of the non-exercised contralateral limb muscle can be also impaired. This crossover fatigue phenomenon is still debated in the literature and very few studies have investigated the influence of eccentric contractions. This study was designed to assess neuromuscular adaptations involved in the crossover fatigue of the non-exercised contralateral knee flexor muscles. Seventeen healthy young men performed a unilateral submaximal eccentric exercise of the right knee flexors until a 20% reduction in maximal voluntary isometric contraction torque was attained in the exercised limb. Before (PRE), immediately after exercise cessation (POST) and 24 hours later (POST24), neuromuscular function and perceived muscle soreness were measured in both the exercised limb and non-exercised limb. In addition, global perceived fatigue was assessed at each measurement time. At POST, significant reductions in maximal voluntary isometric contraction were observed in the exercised limb (-28.1%, p < 0.001) and in the non-exercised limb (-8.5%, p < 0.05), evidencing crossover fatigue. At POST, voluntary activation decreased in the exercised limb only (-6.0%, p < 0.001), while electrically evoked potentiated doublet torque was impaired in both the exercised limb and the non-exercised limb (-11.6%, p = 0.001). In addition, global perceived fatigue significantly increased at POST (p < 0.001). At POST24, all measured variables returned to PRE values, except for perceived muscle soreness scores exhibiting greater values than PRE (p < 0.05). A possible cumulative interaction between peripheral alterations and global perceived fatigue may account for the immediate crossover fatigue observed in the non-exercised limb. [ABSTRACT FROM AUTHOR]

Context: Firefighters participating in mandatory physical exercise sessions are exposed to a high ankle sprains' injury risk. 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 environment 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 (YBT-LQ), Weight Bearing Lunge Test (WBLT), anthropometric measures, postural stability, chronic ankle instability scores (CAIT), previous injuries, and perceived psychosocial work environment (COPSOQ). Results.: During the follow-up, nine firefighters sustained an injury. YBT-LQ and WBLT per-formances, CAIT scores, history of previous ankle sprain and specific dimensions of the COPSOQ significantly differed between injured and uninjured firefighters. Lower limbs asym-metries of the YBT-LQ (i.e., anterior, posteromedial and posterolateral directions) and the WBLT were predictors of ankle sprains. Conclusions: These findings originally provide evidence that intrinsic factors mainly contrib-ute to ankle sprains, although psychosocial work environment assessment could also charac-terize firefighters at risk. [ABSTRACT FROM AUTHOR]

Stereotype threat literature has shown that inducing negative stereotypes can contribute to the underperformance of individuals belonging to a range of stereotyped groups and various domains. The present study sought to observe the effect of the emerging nonexerciser stereotype on performance in a fatiguing task consisting of executing intermittent contractions at 40% of maximal voluntary strength until exhaustion. Comparing 13 young male nonexercisers and 13 young male exercisers, results revealed that both exercisers and nonexercisers increased their performance in the negative stereotype condition. Concerning the nonexercisers this is contrary to classic stereotype threat effects. Valuable results were observed for rate of perceived effort as a mechanism through which performance on a fatiguing task may be affected. This study is encouraging as it revealed that nonexercisers' performance on a prolonged fatiguing task was not decreased by the negative nonexerciser stereotype but rather that, to some degree, stereotype threat could be beneficial to performance. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the influence of 4 weeks of whole-body vibration training added to the conventional training of basketball players. Eighteen competitive basketball players (13 [male], 5 [female], 18-24 years old) were randomly assigned to a whole-body vibration group (WBVG, n = 10; [male] and 3 [female]) or a control group (CG, n = 8; 6 [male] and 2 [female]). During the 4-week period, all subjects maintained their conventional basketball training program. The members of WBVG were additionally trained 3 times a week for 20 minutes on a vibration platform (10 unloaded static lower limb exercises, 40-Hz, 4-mm, Silverplate[R]). Testing was performed before and after the 4-week period and comprised strength assessment, vertical jump performance, and a 10-m sprint test. The maximal voluntary isometric strength of the knee extensors significantly increased (p < 0.001) after vibration training, as did squat jump (SJ) height (p < 0.05), whereas performance of the countermovement jump, drop jump, 30-second rebound jump, and 10-m sprint remained unchanged. The results of the present study indicated that a 4-week whole-body vibration training program added to the conventional training of basketball players during the preseason is an effective short-term stimulus to enhance knee extensor strength and slightly SJ performance. KEY WORDS isometric strength, knee extensors, squat jump, countermovement jump; drop jump, sprint performance

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. [ABSTRACT FROM AUTHOR]

People living with HIV (PLHIV) are not physically active enough. As nonexercisers are perceived as less healthy, less active and less strong, it is likely that PLHIV would be subject to a nonexerciser stereotype threat. We looked to elucidate the effect of the emerging nonexerciser stereotype on handgrip strength performance among less active PLHIV. We also sought to observe the modulating role of self-efficacy in the relationship between stereotype activation and performance. Eighteen PLHIV were recruited to participate in two experimental sessions in which both a stereotypical context and self-efficacy were manipulated. Participants performed a handgrip task comprising a 15-s fatiguing maximal voluntary isometric contraction (MVC) exercise preceded (Pre) and followed (Post) by 5-s MVCs. In each session, (i.e. high and low self-efficacy), four experimental conditions (i.e. Control 1; Control 2; Stereotypical; Self-Efficacy) were performed. A significant performance decrease of the 15-s fatiguing MVC exercise was systematically observed when the nonexerciser stereotype was induced (0.01 < p < 0.001). In addition, this performance re-increased after a high self-efficacy manipulation (p < 0.001). Pre- and post- 5-s MVCs were also significantly depressed after the stereotypical condition (0.01 < p < 0.001) and improved following high self-efficacy manipulation (p < 0.001). Our results revealed a detrimental stereotype threat effect on performance during a handgrip task when the nonexerciser stereotype was activated. A high self-efficacy feedback increased performances significantly whereas no significant difference was observed between the stereotypical and low self-efficacy conditions. These results indicate that self-efficacy can modulate the deteriorating effect of a negative exercise stereotype on task performance in less active PLHIV. Highlights Handgrip strength was decreased and performance fatigability increased when a negative exercise stereotype was induced. Performance fatigability and handgrip strength were restored after positive performance feedback was given. Positive task performance feedback could temper the detrimental effects of a negative stereotypical context among less active people living with HIV. [ABSTRACT FROM AUTHOR]

Objectives: The benefits of physical activity in people living with HIV (PLHIV) are numerous and are largely reported in the literature. Understanding why PLHIV engage or not in physical activity is key to better accompanying health behaviors. Through a qualitative approach, our study sought to identify barriers to and facilitators of physical activity participation in PLHIV. Methods: PLHIV were recruited by purposive sampling. Semi-structured interviews were carried-out in Center and Southern France. The data were analyzed following the principals of thematic analysis. Physical activity level was assessed through questions related to physical activity recommendations and a physical activity questionnaire. Results: Fifteen semi-structured interviews (seven men and eight women; Mage = 46.6; SD = 10.3) were analyzed. Only a third of our sample was considered physically active with almost half being considered inactive according to recommendations. A multidimensional perspective of physical activity barriers and facilitators emerged. Barriers to and facilitators of physical activity were related to the physical, psychological and socio-environmental domains. Discussion: Our research sought to better understand the beliefs and attitudes of PLHIV towards physical activity. Physical activity was overall viewed as beneficial by both active and less active PLHIV; however, PLHIV remain insufficiently active. This is discussed through our multidimensional approach of the barriers to and facilitators of physical activity. [ABSTRACT FROM AUTHOR]