Karpouzi C, Kosmidis I, Petridou A, Bogdanis G, Mougios V (2022). EFFECTS OF PROTEIN SUPPLEMENTATION COMBINED WITH HIGH-INTENSITY FUNCTIONAL TRAINING ON BODY COMPOSITION

AIM: High-intensity functional training (HIFT) is a new version of high-intensity interval training, which has gained interest in recent years and is based on the CrossFit training template, including multijoint movement patterns via both endurance and strengthening exercises. Research has shown positive effects of HIFT on body composition, cardiorespiratory fitness, and muscle performance. However, whether protein supplementation enhances the adaptations to HIFT (as it does with strength training) is less well documented. The aim of this research was to compare the effects of two protein supplements and placebo, combined with short-term HIFT, on body composition in trained young and middle-aged men and women.

MATERIAL & METHOD: Twenty trained men, aged 23–55, and 10 trained women, aged 23–39, underwent 6 weeks of HIFT while receiving 0.6g/kg/day of egg white protein, whey protein, or maltodextrin in a single-blinded (on the part of the researchers), randomized, triple-crossover, and counterbalanced design, with 2 weeks of washout between supplements. Participants received dietary plans designed to be isoenergetic and with protein content of 1g/kg/day. Body composition was assessed through multifrequency bioelectrical impedance analysis (BIA) and full scan dual-energy X-ray absorptiometry (DXA). All measurements were performed before and after each intervention period. Data were analyzed by 3-way ANOVA (supplement x sex x time) with repeated measures on supplement and time. Common parameters of BIA and DXA (lean body mass, percentage lean body mass, fat mass, percentage fat mass) were analyzed by Spearman’ s correlation and Wilcoxon’ s signedrank test. Statistical significance was declared at p<0.05.

RESULTS: After 6 weeks of HIFT, total body mass increased by 0.4 ± 1.9 kg, of which 0.3 ± 1.5 kg were lean body mass, regardless of supplementation, according to BIA (p < 0.05), but not according to DXA. BIA and DXA parameters were significantly correlated but differed between methods (all p<0.001), with BIA overestimating lean body mass.

CONCLUSION: The novel finding of the present study is that short-term HIFT increased lean body mass in trained men and women (according to BIA), but there was no significant effect of protein supplementation.