Eccentric and concentric exercises induce different adaptions in adipose tissue biology

Alterations in adipose tissue (AT) metabolism related to inflammation and adipokine’s production lead to perturbations in its capacity to store lipids and release fatty acids (FA) during feeding/fasting transition or during exercise. Exercise has a beneficial effect on AT metabolism, but conventional trainings are not always suitable for patients with functional limitations. Dynamic eccentric (ECC) exercise prevents the accumulation of AT and may then overcome those limitations. Consequently, this study aimed at investigating AT’s adaptations after ECC training. Nine-week-old male rats were randomly assigned to a control sedentary or three-trained groups for which treadmill slopes modulated exercise oxygen consumption (VO2) and mechanical work (n = 15 per group): (1) + 15% uphill-concentric group (CONC), (2) − 15% downhill group (ECC15, same mechanical work as CONC) and (3) − 30% downhill group (ECC30, same VO2, or oxygen cost as CONC). Body composition and energy expenditure (EE) were measured before and after 8 weeks of training. Subcutaneous AT was collected to study total FA profile and gene expression. Higher total EE was driven by lean mass gain in trained animals. In AT, there was a decrease in arachidonic acid with CONC or ECC15 training. Increased adiponectin, leptin, lipases, Glut4 and Igf1 mRNA levels in ECC15 group suggested major metabolic adaption in AT. In conclusion, ECC could induce beneficial modifications in AT fatty acid profile and the expression of key genes related to metabolism and insulin sensitivity. (AU)

Eccentric and concentric exercises induce different adaptions in adipose tissue biology.

Alterations in adipose tissue (AT) metabolism related to inflammation and adipokine's production lead to perturbations in its capacity to store lipids and release fatty acids (FA) during feeding/fasting transition or during exercise. Exercise has a beneficial effect on AT metabolism, but conventional trainings are not always suitable for patients with functional limitations. Dynamic eccentric (ECC) exercise prevents the accumulation of AT and may then overcome those limitations. Consequently, this study aimed at investigating AT's adaptations after ECC training. Nine-week-old male rats were randomly assigned to a control sedentary or three-trained groups for which treadmill slopes modulated exercise oxygen consumption (VO2) and mechanical work (n = 15 per group): (1) + 15% uphill-concentric group (CONC), (2) - 15% downhill group (ECC15, same mechanical work as CONC) and (3) - 30% downhill group (ECC30, same VO2, or oxygen cost as CONC). Body composition and energy expenditure (EE) were measured before and after 8 weeks of training. Subcutaneous AT was collected to study total FA profile and gene expression. Higher total EE was driven by lean mass gain in trained animals. In AT, there was a decrease in arachidonic acid with CONC or ECC15 training. Increased adiponectin, leptin, lipases, Glut4 and Igf1 mRNA levels in ECC15 group suggested major metabolic adaption in AT. In conclusion, ECC could induce beneficial modifications in AT fatty acid profile and the expression of key genes related to metabolism and insulin sensitivity.

Effects of exercise-induced metabolic and mechanical loading on skeletal muscle mitochondrial function in male rats.

Over the past decades, a growing interest in eccentric (ECC) exercise has emerged, but mitochondrial adaptations to ECC training remain poorly documented. Using an approach for manipulating mechanical and metabolic exercise power, we positioned that for the same metabolic power, training using concentric (CON) or ECC contractions would induce similar skeletal muscle mitochondrial adaptations. Sixty adult rats were randomly assigned to a control (CTRL) or three treadmill training groups running at 15 m·min-1 for 45 min, 5 days weekly for 8 wk at targeted upward or downward slopes. Animals from the CON (+15%) and ECC30 (-30%) groups were trained at iso-metabolic power, whereas CON and ECC15 (-15%) exercised at iso-mechanical power. Assessments were made of vastus intermedius mitochondrial respiration (oxygraphy), enzymatic activities (spectrophotometry), and real-time qPCR for mRNA transcripts. Maximal rates of mitochondrial respiration were 14%-15% higher in CON and ECC30 compared with CTRL and ECC15. Apparent Km for ADP for trained groups was 40%-66% higher than CTRL, with statistical significance reached for CON and ECC30. Complex I and citrate synthase activities were 1.6 (ECC15) to 1.8 (ECC30 and CON) times values of CTRL. Complex IV activity was higher than CTRL (P < 0.05) only for CON and ECC30. mRNA transcripts analyses showed higher TFAM, SLC25A4, CKMT2, and PPID in the ECC30 compared with CTRL. Findings confirm that training-induced skeletal muscle mitochondrial function adaptations are governed by the extent of metabolic overload irrespective of exercise modality. The distinctive ECC30 mRNA transcript pattern may reflect a cytoskeleton damage-repair or ECC adaptive cycle that differs from that of biogenesis.NEW & NOTEWORTHY Anticipating outcomes of eccentric versus concentric training is confounded by differences in mechanical efficiency. Our observations in groups of rats submitted to uphill and downhill running regimens inducing similar levels of metabolic demands or same external power outputs reaffirm that independent of modality, oxygen requirements and not external work governs skeletal muscle mitochondrial function adaptations.

Impact of Eccentric or Concentric Training on Body Composition and Energy Expenditure.

PURPOSE: 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. METHODS: 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 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. RESULTS: 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; ECC15, 11.6 ± 5.10 kJ·d; ECC30, 18.3 ± 4.33 kJ·d) but not in CTRL one. This difference disappeared when BMR was normalized for LBM. CONCLUSIONS: 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.