The Effect of Branched-Chain Amino Acids, Citrulline, and Arginine on High-Intensity Interval Performance in Young Swimmers

High-intensity interval training has drawn significant interest for its ability to elicit similar training responses with less training volume compared to traditional moderate-intensity protocols. The purpose of this study was to examine the effect of co-ingestion of branched-chain amino acids (BCAA), arginine, and citrulline on 8 × 50 m high-intensity interval swim performance in trained young swimmers. This study used a randomized cross-over design. Eight male (age 15.6 ± 1.3 years) and eight female (age 15.6 ± 0.9 years) swimmers completed both amino acids (AA) and placebo (PL) trials. The participants ingested 0.085 g/kg body weight BCAA, 0.05 g/kg body weight arginine and 0.05 g/kg body weight citrulline before the swim test in the AA trial. The average 50 m time was significantly shorter in the AA trial than that in the PL trial. The AA trial was faster than the PL trial in the first, second, and the seventh laps. The AA trial showed significantly higher plasma BCAA concentrations and lower tryptophan/BCAA ratio. The other biochemical parameters and ratings of perceived exertion were similar between the two trials. The results showed that BCAA, arginine, and citrulline, allowed the participants to swim faster in a high-intensity interval protocol in young swimmers

Factor Structure and Correlates of Functional Fitness of Older Adults in Taiwan

Background: The purposes of the study were to test the factor structure of the models of functional fitness for older adults, in which the latent factor flexibility represents scores in chair sit-and-reach and back scratch, and the latent factor Physical Power represents scores in chair stand, arm curl, 8-foot up-and-go, and 2-minute step. Correlates of the latent factors including age, sex, and physical activity level were also investigated. Methods: Functional fitness tests were administered to 94 older adults (age: 73.61 ± 5.77 years). Demographic data were collected and physical activity level was measured by using the Physical Activity Scale for Elderly (PASE). The structural equation modeling technique was used to investigate the factor structure of flexibility model and physical power model as well as the contribution of the correlates. Results: The goodness-of-fit indices were excellent for the flexibility model (χ²-square = 4.725, df = 5, p = 0.451, comparative fit index [CFI] = 1.00, Root mean square error of approximation [RMSEA] = 0.001, standardized root mean square of residuals [SRMR] = 0.0646) and physical power model (χ²-square = 17.962, df = 14, p = 0.209, CFI = 0.981, RMSEA = 0.055, SRMR = 0.0651). Age and sex were significant predictors to flexibility and physical power (p < 0.05). Physical activity level was a significant predictor of flexibility (p < 0.05). Conclusion: Flexibility and physical power decline with advanced age. Males have higher physical power, and females have better flexibility. A higher level of physical activity, as measured by PASE, relates to better flexibility but not physical power