Supervised aerobic exercise improved fitness but not cardiometabolic markers in night-shift nurses
A 12-week randomized trial of 26 physically inactive night-shift hospital nurses found that supervised aerobic training improved cardiorespiratory fitness (VO₂max) compared to a control group, with very high adherence, though cardiometabolic risk markers and body composition did not change significantly.
Night-shift work is associated with increased risk for cardiometabolic disease, yet few structured exercise programs target shift workers. Researchers randomized 26 physically inactive acute care nurses (average age 33 years) working night shifts to either 12 weeks of supervised aerobic training or a wait-list control.
The exercise group performed progressive workouts on a cycle ergometer and treadmill 3 days per week, guided by supervising staff. Adherence was exceptionally high: participants completed 96% of prescribed sessions, with 97% performed at the correct heart rate intensity. The aerobic training group improved VO₂max (a marker of cardiorespiratory fitness) by 0.19 L/min compared to a small decline of 0.04 L/min in the control group—a difference that remained significant after adjusting for age, sex, and baseline differences. However, fasting glucose, insulin, lipid profiles, body composition, grip strength, and muscle power showed no significant between-group changes over the 12 weeks. The small sample size and short intervention window limit generalizability; larger and longer studies are needed to determine whether extended training or different exercise modalities might improve cardiometabolic markers in this population.
The fitness gain (VO₂max increase) is meaningful—roughly a 4–5% improvement in aerobic capacity—and emerged despite no change in body composition or muscle power, suggesting cardiovascular adaptation occurred independently of strength or weight loss. Notably, the control group's VO₂max declined slightly, a pattern consistent with sedentary shift work. The study's exceptional adherence (96% attendance, near-perfect intensity compliance) underscores that night-shift nurses can engage with structured, supervised exercise if logistically supported—a key insight for workplace health programs. That cardiometabolic markers (glucose, cholesterol, triglycerides) did not shift significantly over 12 weeks may reflect the short timeframe; chronic metabolic improvements often require 6–12 months of sustained activity. The authors note this is the first rigorous trial of exercise in shift-working hospital nurses, so the field lacks historical comparisons.
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Open in Cadence →References
- Efficacy and Adherence to a Supervised Aerobic Exercise Training Intervention in Night-Shift Hospital Nurses: A Randomized Controlled Trial. — FASEB journal : official publication of the Federation of American Societies for Experimental Biology (Read the original)
- Gan Y., Yang C., Tong X., et al., “Shift Work and Diabetes Mellitus: A Meta‐Analysis of Observational Studies,” Occupational and Environmental Medicine 72, no. 1 (2015): 72–78.
- Pan A., Schernhammer E. S., Sun Q., and Hu F. B., “Rotating Night Shift Work and Risk of Type 2 Diabetes: Two Prospective Cohort Studies in Women,” PLoS Medicine 8, no. 12 (2011): e1001141.
- Chellappa S. L., Morris C. J., and Scheer F. A., “Circadian Misalignment Increases Mood Vulnerability in Simulated Shift Work,” Scientific Reports 10, no. 18614 (2020): 1–10.
- Scheer F. A., Chellappa S. L., Hu K., and Shea S. A., “Impact of Mental Stress, the Circadian System and Their Interaction on Human Cardiovascular Function,” Psychoneuroendocrinology 103 (2019): 125–1
- Sletten T. L., Cappuccio F. P., Davidson A. J., Van Cauter E., Rajaratnam S. M., and Scheer F. A., “Health Consequences of Circadian Disruption,” Sleep 43, no. 1 (2020): zsz194.