Glucose tolerance and insulin sensitivity following an one-week volleyball competition.
The purpose of the study was to compare glucose tolerance and insulin sensitivity between trained (TR) and competition (CP) states, in relation to cortisol and testosterone levels. Sixteen highly trained volleyball players voluntarily participated in this study. The first testing session (TR state) occurred 1 week before the start of national level volleyball CP, and the second testing session (CP state) occurred next morning after the 1-week CP. Fasted serum sample was used for measuring cortisol and testosterone. Subjects were then orally challenged with 75 g of glucose solution for determinations of oral glucose tolerance test (OGTT) and insulin response. Under both fasted and glucose challenged conditions, glucose levels of CP were not different from TR state, whereas insulin levels of CP were significantly elevated above TR (50 min: from 78.8 +/- 8.7 to 96.6 +/- 8.1 microU/ml, P < 0.05; 80 min: from 62.8 +/- 7.0 to 82.0 +/- 7.3; P < 0.05). Muscle creatine kinase (CK) level in blood was significantly increased above TR, suggesting greater muscle damage by CP. Serum leptin level, percent fat mass, and body weight were not different between two states. CP significantly increased serum cortisol level without significantly change in testosterone level. The new finding of the study was that volleyball CP reduced the whole-body insulin sensitivity significantly compared to TR state. The greater level of insulin concentration under CP state appears to be associated with elevated serum cortisol level. Despites the benefit of increased physical activity on metabolic function is widely recognized, physiological stress associated with CP can result in attenuation of systemic insulin sensitivity compared TR state.
Kuo
Mao-Chuan
MC
Laboratory of Exercise Biochemistry, Taipei Physical Education College, Taiwan, ROC.
Chou
Chia-Hau
CH
Ho
Chung-Fong
CF
Lee
Hsing-Hao
HH
Chang
Wei-Hsiang
WH
Lin
Tzi-Wen
TW
Hou
Chien-Wen
CW
Chien
Kuei-Yu
KY
Liu
Te-Chih
TC
Kuo
Chia-Hua
CH
D000293:Adolescent; D001823:Body Composition / Q000502:physiology; D003402:Creatine Kinase / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000502:physiology*; D013177:Sports / Q000502:physiology*; D013739:Testosterone / Q000097:blood
D007328:Insulin; D013739:Testosterone; D003402:Creatine Kinase; D006854:Hydrocortisone