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

Abstract 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  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.