Grant: Travel Awards - Institute Community Support

With aging, muscle mass decreases whereas adipose tissue mass increases. These changes are associated with an increased risk of developing metabolic alterations and functional decline. High-Intensity Interval Training (HIIT), due to its high effectiveness and short duration, is a promising avenue to prevent these phenomena. Citrulline supplementation (CIT) was shown to increase muscle protein synthesis and increase lipolysis in adipocytes. Therefore, CIT may exert additional beneficial effects when combined with HIIT. The aim of this study was to determine the effects of CIT combined with HIIT in inactive obese older adults. Thirty-nine men and 36 women were involved in a 12-week elliptical HIIT program and randomly and double-blindly divided into 2 groups according to gender: 1) HIIT+CIT (18 men; 19 women) and 2) HIIT+Placebo (PLA, 21 men; 17 women). CIT (10 g/day) or PLA (isovalent products) was ingested once a day for the duration of the exercise program. Body composition was measured pre- and post-intervention. A two-way repeated-measure ANOVA was used to determine the effect of the intervention (HIIT) and supplementation. (CIT vs. PLA) in men and women groups. p <0.05 was considered significant. At baseline, subjects were comparable for all variables. Following the HIIT intervention, total fat mass was further decreased in CIT (CIT: 37.3±4.1 vs 35.6±3.4kg) vs. PLA group (PLA: 34.7±3.9 vs 34.2±4.1kg, p=0.022) in men. In Women, total fat-free mass was further increased in CIT (CIT: 44.1±3.9kg vs 46.6±3.4kg) vs. PLA group (PLA: 40.7±5.1 vs 41.2±5.5kg; p=0.039) following the HIIT intervention. Addition of CIT supplementation to HIIT significantly ameliorates body composition in elderly obese people. These effects appear to involve different sex-dependent mechanisms of action, which is reflected in men by a decrease in adipose tissue mass, but in women by an increase in muscle mass.