Asymmetry between lower limbs during rested and fatigued state running gait in healthy individuals.

Although normal gait is often considered symmetrical in healthy populations, differences between limbs during walking suggest that limbs may be used preferentially for braking or propulsion. The purpose of this study was to evaluate kinematic and kinetic variables, at both rested state and following a two-stage treadmill fatiguing run, for asymmetry between limbs. Kinematic (240Hz) and kinetic (960Hz) running data were collected bilaterally for 20 physically active individuals at both rested and fatigued states. Symmetry angles were calculated to quantify asymmetry magnitude at rested and fatigued states. Paired t-tests were used to evaluate differences between right and left limbs at rested and fatigued states, as well as rested and fatigued states symmetry angles. Variables that have been previously associated with the development of overuse injuries, such as knee internal rotation, knee stiffness, loading rate, and adduction free moment, were found to be significantly different between limbs at both rested and fatigued states. Significant differences in vertical stiffness were found, potentially indicating functional asymmetry during running. Symmetry angle was used to investigate changes in percentage of asymmetry at rested and fatigued states. Small (1-6%), but significant decreases in vertical stiffness, loading rate, and free moment symmetry angles indicate that these variables may become more symmetrical with fatigue. Knee internal rotation and knee stiffness became more asymmetrical with fatigue, increasing by 14% and 5.3%, respectively. The findings of the current study indicate that fatigue induced changes in gait may progress knee movement pattern asymmetry

Hydration Behaviors Before and After an Educational and Prescribed Hydration Intervention in Adolescent Athletes

Context: The effectiveness of education in modifying hydration behaviors in adolescent athletes is unclear. Objective: To assess the hydration status and behaviors of female athletes before and after a 1-time educational intervention and prescribed hydration intervention in a warm, humid, tropical environment. Design: Cohort study. Setting: Non–air-conditioned gymnasium in a tropical environment (indoor wet bulb globe temperature  =  24.0 ± 0.2°C). Patient or Other Participants: Thirty-six female adolescent elite volleyball players (age  =  14.8 ± 0.8 years, height  =  168.2 ± 8.2 cm, mass  =  60.8 ± 9.0 kg, body mass index  =  21.7 ± 2.7, body surface area  =  1.65 ± 0.14 m2, body surface area to mass ratio  =  2.71 ± 0.18 m2·kg−1·10−2) participated. Intervention(s): Four observational periods consisting of 3 practices per observational period separated by 48 hours. The 4 periods included a control period, educational intervention, prescribed hydration intervention (PHI), and observational follow-up (OF-U). After the control period, an educational intervention consisting of a slide presentation was provided to the participants, followed by a week of observation. In the PHI, a precalculated volume of water based on individual sweat rate was consumed every 20 minutes during each 2-hour practice. During all other periods, participants consumed their fluid of choice ad libitum. The order of the treatment periods was not randomized and was the same for all participants. Main Outcome Measure(s): Prepractice to postpractice changes in body mass (ΔBM), percentage of body mass lost (%BML), urine specific gravity, urine color, urine osmolality, sweat rate, and volume of fluid consumed (Fvol). Results: The PHI was the only period during which participants maintained body mass (ΔBM  =  0.05 ± 1.3%); Fvol consumed was greatest during this time (Fvol  =  1.3 ± 0.4 L; F1,3  =  34.869, P ≤ .001). The ΔBM was less for the PHI (ΔBM  =  0.05 ± 0.9 kg, %BML  =  0.04 ± 1.3%) than the OF-U period (ΔBM  =  −0.7 ± 1.1 kg, %BML  =  −1.2 ± 1.9%; F1,3  =  6.220, P  =  .01). The Fvol (1.3 ± 0.4 L) and percentage of fluid consumed (143.7 ± 110.8%) to restore sweat loss for the PHI period were higher than for any other period (F1,3  =  34.869, P ≤ .001). None of the participants experienced serious dehydration in any of the conditions. Conclusions: A 1-time education session alone was not successful in changing hydration behaviors. However, prescribing individualized hydration protocols improved hydration for adolescents exercising in a warm, humid environment