Original Research ARTICLE
Differences in Exercise Capacity and Responses to Training in 24 Inbred Mouse Strains
- 1Department of Health and Kinesiology, Texas A&M University, United States
Changes in cardiorespiratory fitness in response to a standardized exercise training protocol differ substantially between individuals. Results from cross-sectional, twin, and family studies indicate genetics contribute to individual differences in both baseline exercise capacity and the response to training. Exercise capacity and responses to training also vary between inbred strains of mice. However, such studies have utilized a limited number of inbred strains. Therefore, the aim of this study was to characterize exercise-training responses in a larger number of genetically diverse strains of inbred mice and estimate the contribution of genetic background to exercise training responses. Eight-week old male mice from 24 inbred strains (n = 4-10/strain) performed a graded exercise test before and after 4 weeks of exercise training. Before training, exercise capacity was significantly different between strains when expressed as time (range = 21 - 42 min) and work performed (range = 0.42 - 3.89 kg·m). The responses to training also were significantly different between strains, ranging from a decrease of 2.2 min in NON/ShiLtJ mice to an increase of 8.7 min in SWR/J mice. Changes in work also varied considerably between the lowest (-0.24 kg·m in NON/ShiLtJ) and highest (+2.30 kg·m in FVB/NJ) performing strains. Heart and skeletal muscle masses also varied significantly between strains. Two broad sense heritability estimates were calculated for each measure of exercise capacity and for responses to training. For change in run time, the intraclass correlation between mice within the same inbred strain (rI) was 0.56 and the coefficient of genetic determination (g2) was 0.39. Heritability estimates were similar for the change in work: rI = 0.52 and g2 = 0.35. In conclusion, these results indicate genetic background significantly influences responses to exercise training.
Keywords: exercise training, treadmill running, heritability, inbred strains, skeletal muscle, Heart
Received: 11 Sep 2017;
Accepted: 15 Nov 2017.
Edited by:Kimberly Huey, Drake University, United States
Reviewed by:Will Hopkins, Victoria University, Australia, Australia
I. M. Olfert, West Virginia University School of Medicine, United States
Kevin A. Murach, University of Kentucky, United States
Copyright: © 2017 Avila, Kim and Massett. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Michael P. Massett, Texas A&M University, Department of Health and Kinesiology, College Station, United States, email@example.com