Functional losses associated with spaceflight negatively influence astronaut health and mission success. Exercise combined with protein supplementation is a promising countermeasure. Blood flow restricted (BFR) exercise is an effective modality, but synergistic benefits when combined with protein supplementation are not clearly identified. The purposes of this investigation were to determine if blended (e.g., whey and casein) protein supplementation combined with BFR exercise favorably altered body composition, muscle function, and cardiovascular health during a short training program. MethodsSixteen participants (female = 50%, age = 36.0 ± 10.1 y, BMI = 27.2 ± 5.0 kg/m2) completed a six-week, ground-based, double-blind, placebo controlled, clinical trial. Participants were randomly assigned to daily blended protein supplementation (28 g protein with 3 g leucine) or an isocaloric placebo. Pre-and post-intervention, body composition, muscular strength and function, balance, and cardiovascular health were evaluated. Dietary intake was evaluated pre-, mid-, and post-intervention. ResultsDietary protein intakes for the supplement and placebo groups, respectively, were beyond adequate (1.6 ± 0.2 g kg·day−1 and 1.0 ± 0.2 g kg·day−1; p = 0.004) and remained consistent throughout the study. However, total leucine intake increased from 3.5 ± 3.2 g·day−1 to 5.6 ± 1.5 g·day−1 following supplementation (p = 0.002). Post-training, knee flexor strength, sit-to-stand repetitions, and gait speed significantly increased, while resting heart rate declined (p < 0.05), with no between group differences. ConclusionExercise with intermittent BFR improves muscular strength and function while positively influencing cardiovascular health in adults. The leucine-rich protein supplement provided no additional benefits. These data suggest potential as an adjunct countermeasure for negative effects of disuse; however, further spaceflight analog-specific data are required before implementation.
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