To compare the effects of 8-wk eccentric (ECC) versus concentric (CON) training using downhill and uphill running in rats on whole body composition, bone mineral density (BMD), and energy expenditure.
Animals were randomly assigned to one of the following groups: 1) control (CTRL), 2) +15% uphill-running slope (CON), 3) −15% downhill-running slope (ECC15), and 4) −30% downhill-running slope (ECC30). Those programs enabled to achieve conditions of isopower output for CON and ECC15 and of iso-oxygen uptake (V˙O2) for CON and ECC30. Trained rats ran 45 min at 15 m·min−1 five times per week. Total body mass, fat body mass, and lean body mass (LBM) measured through EchoMRI™, and 24-h energy expenditure including basal metabolic rate (BMR) assessed using PhenoMaster/LabMaster™ cage system were obtained before and after training. At sacrifice, the right femur was collected for bone parameters analysis.
Although total body mass increased in all groups over the 8-wk period, almost no change occurred for fat body mass in exercised groups (CON, −4.8 ± 6.18 g; ECC15, 0.6 ± 3.32 g; ECC30, 2.6 ± 6.01 g). The gain in LBM was mainly seen for ECC15 (88.9 ± 6.85 g) and ECC30 (101.6 ± 11.07 g). ECC was also seen to positively affect BMD. An increase in BMR from baseline was seen in exercise groups (CON, 13.9 ± 4.13 kJ·d−1; ECC15, 11.6 ± 5.10 kJ·d−1; ECC30, 18.3 ± 4.33 kJ·d−1) but not in CTRL one. This difference disappeared when BMR was normalized for LBM.
Results indicate that for iso-V˙O2 training, the impact on LBM and BMD is enhanced with ECC as compared with CON, and that for isopower but lower V˙O2 ECC, an important stimulus for adaptation is still observed. This provides further insights for the use of ECC in populations with cardiorespiratory exercise limitations.
1Human Nutrition Unit, ASMS Team, CRNH Auvergne, Clermont-Ferrand, FRANCE
2Faculty of Health Sciences, University of Ottawa, Ottawa, ON, CANADA
3Department of Sports Medicine and Functional Explorations, University Hospital of Clermont-Ferrand, Clermont-Ferrand, FRANCE
4Human Nutrition Unit, IEN Team, Theix, FRANCE
5Delegation to Clinical Research and Innovation, University Hospital of Clermont-Ferrand, Clermont-Ferrand, FRANCE
Address for correspondence: Julianne Touron, Unité de Nutrition Humaine, Laboratoire de Nutrition Humaine, 58 rue Montalembert, B.P. 321, 63009 Clermont-Ferrand, France; E-mail: Julianne.TOURON@uca.fr.
Submitted for publication December 2018.
Accepted for publication March 2019.
Online date: March 26, 2019