We determined whether cold water swimming for six consecutive months results in adaptive changes in body composition and insulin sensitivity. Thirty healthy subjects aged 50.2 ± 9.4 years were exposed to cold water at least twice a week. Body composition was determined and serum glucose and insulin served to calculate beta-cell function, insulin sensitivity, and resistance using HOMA2. Compared with control subjects, swimmers were overweight, and had greater percent body fat and beta cell function. Women had lower values of BMI, fat free mass, muscle mass, visceral adipose tissue level, and greater percent body fat than men. Increased insulin sensitivity and decreased insulin secretion and resistance from beginning to middle of swim season was observed in females and in lean subjects. Findings suggest that men and women differ in regard to body composition and response to repeated cold exposure. Cold water swimming may beneficially modulate insulin sensitivity in cold acclimated lean swimmers.
Magdalena Gibas-Dorna, Zuzanna Chęcińska, Emilia Korek, Justyna Kupsz, Anna Sowińska and Hanna Krauss
Javier T. Gonzalez, Martin J. Barwood, Stuart Goodall, Kevin Thomas and Glyn Howatson
Unaccustomed eccentric exercise using large muscle groups elicits soreness, decrements in physical function and impairs markers of whole-body insulin sensitivity; although these effects are attenuated with a repeated exposure. Eccentric exercise of a small muscle group (elbow flexors) displays similar soreness and damage profiles in response to repeated exposure. However, it is unknown whether damage to small muscle groups impacts upon whole-body insulin sensitivity. This pilot investigation aimed to characterize whole-body insulin sensitivity in response to repeated bouts of eccentric exercise of the elbow flexors. Nine healthy males completed two bouts of eccentric exercise separated by 2 weeks. Insulin resistance (updated homeostasis model of insulin resistance, HOMA2-IR) and muscle damage profiles (soreness and physical function) were assessed before, and 48 h after exercise. Matsuda insulin sensitivity indices (ISIMatsuda) were also determined in 6 participants at the same time points as HOMA2-IR. Soreness was elevated, and physical function impaired, by both bouts of exercise (both p < .05) but to a lesser extent following bout 2 (time x bout interaction, p < .05). Eccentric exercise decreased ISIMatsuda after the first but not the second bout of eccentric exercise (time x bout interaction p < .05). Eccentric exercise performed with an isolated upper limb impairs whole-body insulin sensitivity after the first, but not the second, bout.
Jill Pawlowski, E. Andrew Pitchford, Daniel W. Tindall and Seo Hee Lee
Edited by ZáNean McClain
significantly decreased serum fasting insulin and homeostatic model assessment version 2 measuring insulin resistance (HOMA2-IR; p ≤ .044) and significantly increased VO 2peak ( p ≤ .001) compared with the control group. However, no differences were observed in adipose tissue metabolism or peripheral