New Study Suggests Best Times to Train For Abdominal Fat and Blood Pressure Reduction

On May 31, 2022, a study published in Frontiers in Physiology sought to find the best times for men and women to train for optimized health and performance outcomes. While there isn’t a position stand on the ideal time of day to train, the study concluded that training in the morning "reduced abdominal fat and blood pressure," while evening training "enhanced muscular performance in the women." (1)

For men, training in the evening "increased fat oxidation and reduced systolic blood pressure and fatigue." The study did not specify whether any women or men who participated were trans and did not seem to include any nonbinary participants. Let’s dive into the methods this study used to conclude the best time of day to exercise.

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[Related: New Study Shows the Sooner You Swap to a Healthy Diet, the More Years You Can Add to Your Life]

Ideal Exercise Times

The study featured 30 women between the ages of 34 and 50 and 26 men between the ages of 37 and 53. All of the participants were randomized into groups that trained in the morning (between 6:00 a.m. and 8:00 a.m.) and in the evening (between 6:30 p.m. and 8:30 p.m.) for 12 weeks — all training remained consistent between groups. The following measurements and means by which they took those measurements were taken as follows:

• Muscular Strength — one-rep max bench press, one-rep max leg press
• Endurance — sit-ups and push-ups
• Power — jump squats, bench throws
• Body Composition — fat mass, abdominal fat
• Blood Pressure
• Respiratory Exchange Ratio
• Profile of Mood States
• Diet

Body composition was assessed via iDXA, a densitometer for body composition and bone mineral assessment. (2) Twenty-seven of the 30 women and 20 of the 26 men completed all 12 weeks of the study. Women in the evening group could bench press more weight and perform more push-ups than the morning group. However, the morning group performed significantly more jump squats and achieved more than double the reduction in body fat (two percent versus five percent) and more than three times the reduction in abdominal fat (three percent versus 10 percent).

This suggests that women who seek to "optimize total body and abdominal fat loss, lowering of blood pressure, and increasing lower body muscular power" should train in the morning. Women who want to improve "upper-body muscular performance" should train in the evening.

For the male groups, those who trained in the evening reduced systolic blood pressure significantly more than their counterparts who trained in the morning. The study determined that men and women respond differently to training in the morning versus the evening due to circadian rhythms‘ potential impact on performance.

References

1. Arciero, P., Ives, S., Mohr, A., Robinson, N., Escudero, D., & Robinson, J. et al. (2022). Morning Exercise Reduces Abdominal Fat and Blood Pressure in Women; Evening Exercise Increases Muscular Performance in Women and Lowers Blood Pressure in Men. Frontiers In Physiology, 13. doi: 10.3389/fphys.2022.893783
2. Hull, H., He, Q., Thornton, J., Javed, F., Allen, L., Wang, J., Pierson, R. N., Jr, & Gallagher, D. (2009). iDXA, Prodigy, and DPXL dual-energy X-ray absorptiometry whole-body scans: a cross-calibration study. Journal of clinical densitometry: the official journal of the International Society for Clinical Densitometry, 12(1), 95–102. https://doi.org/10.1016/j.jocd.2008.09.004

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