High intensity interval training combined with L-citrulline supplementation: Effects on physical performance in healthy older adults.

Introduction: The aim of this study was to evaluate the effect of citrulline (CIT) supplementation combined to high intensity interval training (HIIT) on physical performance in healthy older adults.

Methods: This study is a secondary analysis from a double-blind, randomized trial. Among the participants (sedentary & inactive older adults aged over 65 yrs), 44 were non obese (BMI <30 kg/m) and completed the intervention: Placebo + HIIT (PLA; n = 21) or CIT + HIIT (n = 23). All participants ingested either 10 g of CIT supplementation/day or placebo and followed HIIT sessions (30 min/session; cycle: 30 s > 85% of maximal heart rate (HR) and Borg scale >17/20 + 1:50 min at 65% HR and Borg scale between 13 and 16) on an elliptical device 3 times per week over a 12-week period. Body composition, muscle strength, muscle power, functional capacities (unipodal balance; self-paced and fast Timed Up and Go (nTUG; fTUG); chair test; step tests; 4-meter walking test; 6-minute walking test); dietary intake, energy expenditure and biological markers were measured pre and post-intervention. A repeated-measure analysis of variance was used to estimate time (HIIT intervention), group (PLA vs. CIT) and time*group effects.

Results: The decrease in BMI (p = 0.02) and android fat mass (p = 0.05) were significantly greater in the HIIT+CIT group than in the HIIT+PLA group. Finally, a greater increase in self-paced gait speed (nTUG) (p = 0.02) and fast-paced gait speed (fTUG) (p = 0.03) were also observed in the HIIT+CIT group than in the HIIT+PLA group.

Conclusion: CIT supplementation combined to HIIT is more effective in improving functional capacities and body composition in healthy older adults than HIIT alone.