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Updated: Jan 15, 2026
Conducting Maximal and Submaximal Endurance Exercise Testing to Measure Physiological and Biological Responses to Acute Exercise in Humans
Published on: October 17, 2018
No sex differences in fat oxidation in response to exercise prescribed according to maximal heart rate or ventilatory
Todd A Astorino1, Alex J MacDonald2, Alex Anderson2
1Department of Kinesiology, California State University-San Marcos, 333. S. Twin Oaks Valley Road, UNIV 320, San Marcos, CA, 92096-0001, USA. astorino@csusm.edu.
Aim:
Most data report that women exhibit higher fat oxidation (FOx) than men during exercise, yet studies typically prescribe exercise using percent maximal heart rate or oxygen uptake (%HR/VO2max) which does not match metabolic strain.
Purpose:
To examine sex differences in substrate metabolism when exercise is prescribed using %HRmax and ventilatory threshold (VT).
Methods:
Active men (n = 24) and women (n = 25) underwent incremental cycling to determine VO2max, HRmax, peak power output (PPO), and VT. After an overnight fast, participants subsequently completed 35 min of cycling at 62%HRmax or 30% below VT.
Results:
At 62%HRmax (workload = 31 ± 6 vs. 24 ± 7%PPO, p < 0.001), there was no difference in RER (0.88 ± 0.05 vs. 0.85 ± 0.06, p = 0.12) or FOx (4.6 ± 2.3 vs. 4.8 ± 2.0 mg/kg FFM/min, p = 0.78) between men and women, although men revealed higher carbohydrate oxidation (CHOOx) versus women (16.4 ± 4.8 vs. 12.9 ± 6.1 mg/kg FFM/min, p = 0.03). Cycling at 30% below VT (workload = 46 ± 5 vs. 44 ± 7%PPO, p = 0.20) revealed no difference in RER (0.92 ± 0.06 vs. 0.90 ± 0.05, p = 0.16), FOx (3.9 ± 3.2 vs. 4.8 ± 2.6 mg/kg FFM/min, p = 0.49), or CHOOx (27.3 ± 7.8 vs. 24.6 ± 11.1 mg/kg FFM/min, p = 0.35).
Conclusion:
Data reveal no sex differences in FOx when exercise is prescribed according to VT or %HRmax.
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