Metabolic dysfunction is associated with excess adipose tissue, and interventions that improve body composition may mitigate related health consequences. Acute nutritional and exercise strategies have the potential to shift metabolic processes toward those favoring fat oxidation. PURPOSE: The purpose of this study was to investigate the effects of high-intensity resistance training (HIRT) and pre-exercise protein (PRO) ingestion on post-exercise respiratory exchange ratio (RER) in lean (LN) and overweight (OW) females. METHODS: Twenty recreationally active females (LN: n =10, body fat percentage: 22.6 ± 4.0; OW: n = 10, body fat percentage: 30.8 ± 3.2) completed two experimental sessions, consisting of HIRT and two acute nutritional interventions: PRO and placebo (PLA). RER was analyzed via indirect calorimetry (TrueOne 2400, Parvo Medics Inc., Sandy, UT) at the following timepoints: baseline (BASE), immediately-post (IP), 30-min (30), and 60-min (60) post-HIRT. A 2 x 2 x 4 mixed-factor, repeated measures analysis of variance was used to assess statistical significance on 5-minute averaged RER values. RESULTS: Data are presented as means ± SD. LN and OW females displayed significantly lower 30-RER (LN: 0.75 ± 0.04, OW: 0.74 ± 0.06) and 60-RER (LN: 0.76 ± 0.04, OW: 0.73 ± 0.06) post-HIRT when compared to BASE. PRO ingestion resulted in significantly lower RER values in OW females IP-HIRT (PRO: 0.74 ± 0.05, PLA: 0.78 ± 0.08; p = 0.02), and lower RER values in LN females at all timepoints post-HIRT (all p < 0.05), compared to PLA. CONCLUSION: These results show that HIRT effectively reduces RER in LN and OW females for 60 min post-exercise, and that the addition of PRO ingestion prior to HIRT provides a synergistic effect. However, the differential responses between LN and OW females highlight the need for further research to optimize protein dosing and explore the underlying hormonal and physiological mechanisms.
