In order to elucidate muscle functional changes by acute reloading, contractile and fatigue properties of the rat soleus muscle were investigated at three weeks of hindlimb suspension and the following 1 hr, 5 hr, 1 d, and 2 weeks of reloading. Compared to age-matched controls, three weeks of unloading caused significant changes in myofibrillar alignments, muscle mass relative to body mass (-43%), normalized tension (-35%), shortening velocity (+143%), and response times. Further significant changes were not observed during early reloading, because the transitional reverse process was gradual rather than abrupt. Although most of the muscle properties returned to the control level after two weeks of reloading, full recovery of the tissue would require more than the two-week period. Delayed recovery due to factors such as myofibrillar arrangement and fatigue resistance was apparent, which should be considered for rehabilitation after a long-term spaceflight or bed-rest.
Animals ; Hindlimb Suspension ; Lactic Acid/metabolism ; Microscopy, Electron ; Muscle Contraction/*physiology ; Muscle Fatigue/*physiology ; Muscle, Skeletal/cytology/*physiology ; Myofibrils/ultrastructure ; Rats ; Rats, Sprague-Dawley ; Research Support, Non-U.S. Gov't ; Weight-Bearing/physiology

BACKGROUND: The purpose of this study was to investigate the relationship between sleep patterns and health in Korea, using data from the Korea National Health and Nutrition Examination Survey 2016–2017.METHODS: In total, 12,646 individuals were divided into those who sleep more than 5 hours and less than 5 hours per day during the week. In addition, 512 people who slept less than 5 hours a day on weekdays were further classified into those sleeping on average less than 5 hours a day and those sleeping more than 5 hours a day on weekends.RESULTS: People who slept on average for more than 5 hours on weekdays were taller, had lower body mass index, and lower fasting blood sugar and glycated hemoglobin levels than those who slept less than 5 hours on weekdays. In addition, the percentage of people with osteoporosis, cervical cancer, and depression was lower in the group that slept on average 5 hours or more on weekdays than in the group that slept less than 5 hours on weekdays. Among those who slept on average less than 5 hours a day on weekdays, individuals who slept more than 5 hours a day on weekends were taller and had lower fasting blood glucose and glycated hemoglobin than those who slept less than 5 hours a day on weekends. The prevalence of patients with angina, arthritis, osteoporosis, colon cancer, and depression was higher in the group who slept less than 5 hours a day on weekends.CONCLUSION: There are differences in height, body mass index, fasting blood sugar level and glycated hemoglobin level and in the prevalence of angina, arthritis, osteoporosis, colon cancer, and depression according to weekday and weekend sleep times.
Adult ; Arthritis ; Blood Glucose ; Body Height ; Body Mass Index ; Colonic Neoplasms ; Depression ; Fasting ; Hemoglobin A, Glycosylated ; Humans ; Korea ; Nutrition Surveys ; Osteoporosis ; Prevalence ; Uterine Cervical Neoplasms