Objective: Aerobic exercise on land decreases arterial stiffness, however, the effect of exercise in water on arterial stiffness has not been clear. This study investigated the effect of a 15-min cycling exercise on land and that in water on pulse wave velocity (PWV) as an index of arterial stiffness. Methods: Nine healthy young men were randomly performed exercise on land and exercise in water equivalent to 50% of each maximum oxygen uptake on separate days. The PWV from carotid to femoral artery (aortic PWV) and femoral to posterior tibial artery (leg PWV) were measured at baseline and 15, 30, 60 min after exercise. Results: The heart rate in water was significantly lower during exercise than that on land. In addition, the carbon dioxide output and respiratory exchange ratio during exercise were significantly greater in water. Body temperature increased after the exercise on land but decreased after the exercise in water. Although the aortic PWV and leg PWV decreased concomitantly with decrease in SBP and DBP after the exercise on land, there were no significant changes after the exercise in water. Conclusion: Although acute exercise on land decreased arterial stiffness after exercise, acute exercise in water of the same exercise load did not. The differences in body temperature and blood pressure after exercise may result in diverse arterial stiffness after exercise.

Objective: Osteoporotic vertebral fracture (OVF) is conventionally treated with conservative management such as bed rest, but a relatively prolonged bed rest has the potential risk of muscle disuse atrophy. This study aimed to examine whether the 2-week of rigorous bed rest affects muscle disuse atrophy in OVF patients.Patients and Methods: A total of 54 OVF patients (16 males; 38 females; mean age, 80.2 ± 9.2 years) were treated with an initial 2-week rigorous bed rest by hospitalization with persistent rehabilitation. Cognitive function, swallowing function, grip strength, and lower extremity circumference were evaluated at three-time points (admission, end of bed rest, and discharge).Results: Of the 51 patients who were able to walk independently before the injury, one patient (2.0%) had to use a wheelchair after the injury. During hospitalization, cognitive function decline was observed in 33.3% of patients, but not in patients with Revised Hasegawa’s Dementia Scale score ≥25 at admission. Swallowing function decline was observed in one patient, and none of the patients developed aspiration pneumonia during hospitalization. The grip strength significantly improved both at the end of bed rest (P=0.04) and discharge (P=0.02). Although the lower extremity circumference significantly decreased at the end of bed rest (P<0.01), it was recovered afterward. The lower extremity circumference did not significantly differ between the admission and discharge (P=0.17).Conclusion: Our results suggested that conservative treatment of OVF through an initial 2-week rigorous bed rest with persistent hospital rehabilitation poses a low risk of muscle disuse atrophy. If cognitive dysfunction is observed on admission, close monitoring for exacerbation should be performed during the hospital stay.