Comparison of Post-Exercise Lipid Oxidation Rates Between Lower and Upper-Body Resistance Training in Well-Trained Females

INTRODUCTION: Lipid oxidation (LOx) is a relevant physiological process linked to metabolic health. Despite growing interest in resistance training (RT) as a means to influence substrate utilization, LOx responses in females remain poorly characterized, with no study examining whether lower- and upper-body RT elicits different LOx patterns during the recovery period following exercise. This distinction may be relevant because lower-body exercises involves greater fat-free mass (FFM) and energy expenditure, whereas upper-body exercises recruit less FFM, potentially influencing metabolic effects. PURPOSE: To determine if LOx rates after exercise differ between lower- and upper-body RT in well-trained females. METHODS: Twenty-two females (age: 25.4±5.6years, FFM: 44.5±4.9kg, mean relative strength: 1.1±0.2) completed repetition-maximum (RM) tests in the barbell back squat (BS) and bench press (BP). From these, an equated volume-load (sets×repetitions×load) was determined using 65%1RM of participants' BS and BP. Metabolic testing was completed before either the BS or BP, then immediately (IP), 30-, 60-, and 90-min post-exercise. RESULTS: No significant differences were found between BS or BP LOx rates (p>0.05). LOx relative to FFM averaged 1.57±0.4 mg·kg⁻¹FFM·min⁻¹ across both exercises from IP to 90-min post-exercise, representing a 45% and 65% increase from baseline in the BP and BS, respectively. At 90-min post-RT, LOx reached 1.78±0.37mg·kg⁻¹FFM·min⁻¹ (SEM=0.08) for the BS and 1.65±0.31mg·kg⁻¹FFM·min⁻¹ (SEM=0.07) for BP, with no between-condition differences (p>0.05). Resting energy expenditure (REE) was not different between conditions (p>0.05), with a pooled average of 1.04±0.13kcal·min⁻¹ from IP to 90-min post-RT. CONCLUSIONS: These data demonstrate that RT, differing in FFM but not volume-load, stimulates comparable LOx rates and REE responses during the post-exercise recovery period. These findings support versatility in exercise prescription, indicating that RT of different muscle regions can produce similar acute metabolic outcomes.