Adaptation of Insulin-Resistance Indicators to a Repeated Bout of Eccentric Exercise in Human Skeletal Muscle

• Published in: International journal of sport nutrition and exercise metabolism 2010-06, Vol.20 (3), p.181-190
• Main Authors: Green, Michael S, Doyle, J. Andrew, Ingalls, Christopher P, Benardot, Dan, Rupp, Jeffrey C, Corona, Benjamin T
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Adult; Area Under Curve; Blood Glucose - metabolism; Creatine Kinase - metabolism; eccentric exercise; exercise; Exercise Test; Female; glucose tolerance; Glucose Tolerance Test; homeostasis; Humans; Insulin - blood; Insulin Resistance; Isometric Contraction - physiology; Muscle, Skeletal - physiology; Muscle, Skeletal - physiopathology; oral administration; oral glucose-tolerance test; Physical Exertion - physiology; protective effect; Running - physiology; skeletal muscle; Time Factors; Young Adult
• ISSN: 1526-484X; 1543-2742
• DOI: 10.1123/ijsnem.20.3.181

This study determined whether disrupted glucose and insulin responses to an oral glucose-tolerance test (OGTT) induced by eccentric exercise were attenuated after a repeated bout. Female participants (n = 10, age 24.7 ±3.0 yr, body mass 64.9 ± 7.4 kg, height 1.67 ± 0.02 m, body fat 29% ± 2%) performed 2 bouts of downhill running (DTR 1 and DTR 2) separated by 14 d. OGTTs were administered at baseline and 48 hr after DTR 1 and DTR 2. Maximum voluntary isometric quadriceps torque (MVC), subjective soreness (100-mm visual analogscale), and serum creatine kinase (CK) were assessed pre-, post-, and 48 hr post-DTR 1 and DTR 2. Insulin and glucose area under the curve (38% ± 8% and 21% ± 5% increase, respectively) and peak insulin (44.1 ±5.1 vs. 31.6 ± 4.0 μU/ml) and glucose (6.5 ± 0.4 vs. 5.5 ± 0.4 mmol/L) were elevated after DTR 1, with no increase above baseline 48 hr after DTR 2. MVC remained reduced by 9% ± 3% 48 hr after DTR 1, recovering back to baseline 48 hr after DTR 2. Soreness was elevated to a greater degree 48 hr after DTR 1 (48 ± 6 vs. 13± 3 mm), with a tendency for greater CK responses 48 hr after DTR 1 (813 ± 365 vs. 163 ± 43 U/L, p = .08). A novel bout of eccentric exercise confers protective effects, with subsequent bouts failing to elicit disruptions in glucose and insulin homeostasis.