Smorawinski, J., Nazar, K., Kaciuba-Uscilko, H., Kaminska, E., Cybulski, G., Kodrzycka, A., Bicz, B., & Greenleaf, J. E. (2001). Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men. Journal of Applied Physiology, 91, 249-257.

Sedentary men (N = 12), endurance-trained male athletes (N = 10), and strength-trained male athletes (N = 10) undertook three days of bed rest. Before and after the bed rest, an incremental exercise test to volitional exhaustion was performed.

Peak oxygen uptake (VO2peak) was significantly reduced more in the endurance group (-17%) than in the other two groups (-10%). Resting and exercise respiratory exchange ratios were increased in the athletes. Exercise heart rate increased and stroke volume decreased in the sedentary group. Submaximal lactate and lactate threshold significantly decreased (from 71 to 60% VO2peak) in the endurance group. An earlier increase in norephinephrine concentration, a reduced increase in hGH concentration, and accentuated plasma renin activity and cortisol elevations during exercise were observed in the endurance athletes. These changes were not observed in the other two groups.

Implications. Three days of bed rest affected endurance trained athletes more than strength-trained or sedentary males. The trained state of endurance athletes is more tenuous than in strength-trained athletes.

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