The intensity of large muscle mass exercise declines at altitude due to reduced oxygen delivery to active muscles. The purpose of this investigation was to determine if the greater limb blood flow during single-leg cycling prevents the reduction in tissue oxygenation observed during traditional double-leg cycling in hypoxic conditions. Ten healthy individuals performed bouts of double and single-leg cycling (4, four-minute stages at 50–80% of their peak oxygen consumption) in hypoxic (15% inspired O²) and normoxic conditions. Heart rate, mean arterial pressure, femoral blood flow, lactate, oxygenated hemoglobin, total hemoglobin, and tissue saturation index in the vastus lateralis were recorded during cycling tests. Femoral blood flow (2846 ± 912 mL/min) and oxygenated hemoglobin (−2.98 ± 3.56 au) during single-leg cycling in hypoxia were greater than double-leg cycling in hypoxia (2429 ± 835 mL/min and −6.78 ± 3.22 au respectively, p ≤ 0.01). In addition, tissue saturation index was also reduced in the double-leg hypoxic condition (60.2 ± 3.1%) compared to double-leg normoxic (66.0 ± 2.4%, p = 0.008) and single-leg hypoxic (63.3 ± 3.2, p < 0.001) conditions. These data indicate that while at altitude, use of reduced muscle mass exercise can help offset the reduction in tissue oxygenation observed during larger muscle mass activities allowing athletes to exercise at greater limb/muscle specific intensities.

Alterations in running shoe design have been studied and used in the prevention of injury and enhancement of performance allowing running shoe companies to market to a variety of runners based on skill level, foot-strike pattern, and even sex. These alterations have been shown to affect biomechanical and physiological variables associated with running. Some shoe companies have designed shoes specifically for biological female runners due to the morphological differences found between male and female feet. The purpose of this study is to determine if sex-specific running shoes can alter female runner biomechanics or physiology. Female runners were asked to run in the male and female models of the Altra Torin 4 Plush shoe to determine if there were differences in ground reaction forces (GRFs), sagittal plane joint angles and moments, oxygen consumption (VO₂), respiratory exchange ratio (RER), and perceived level of comfort while running; There were no significant differences in GRFs, sagittal joint angles and moments, VO₂, RER, or perceived comfort; There were no differences in measured biomechanical or physiological variables between the female and male version of the shoes suggesting that the alterations made to the female-specific shoe do not provide any additional benefit to female recreational runners.

Introduction: Identifying an accurate, user friendly alternative to skinfold calipers may allow for accurate assessment of body composition in more applied settings, such as various training and competition venues.  The purpose of our study was to determine the validity of B-mode ultrasound (BMUS) for body composition assessment by comparing this method to values obtained using air displacement plethysmography (ADP). Methods: Twenty-four active runners underwent two forms of body composition assessment during a single lab visit; ADP and BMUS. ADP body density was estimated using an air displacement chamber in combination with measured lung volume. BMUS body density was estimated from measuring the Jackson-Pollock 7 site skinfolds with a portable, app-based ultrasound device to determine subcutaneous fat thickness. Images were analyzed using proprietary software. Body density values for both methods were converted to body fat percentage using the Siri equation. A paired samples t-test was used to compare values obtained from ADP and BMUS. Results: There was no difference between ADP (18.3 ± 7.3%) and BMUS (17.2 ± 7.6%; p = 0.1) for percent body fat. Conclusions: BMUS provides a valid method for assessing body composition when compared to ADP, thus providing a portable, accurate method for assessing body composition in applied settings.

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