Mechanical and Structural Remodeling of Cardiac Muscle after Aerobic and Resistance Exercise Training in Rats

Aerobic and Resistance Training Attenuate Differently Knee Joint Damage Caused by a High-Fat-High-Sucrose Diet in a Rat Model

OBJECTIVE

Obesity and associated low-level local systemic inflammation have been linked to an increased rate of developing knee osteoarthritis (OA). Aerobic exercise has been shown to protect the knee from obesity-induced joint damage. The aims of this study were to determine (1) if resistance training provides beneficial metabolic effects similar to those previously observed with aerobic training in rats consuming a high-fat/high-sucrose (HFS) diet and (2) if these metabolic effects mitigate knee OA in a diet-induced obesity model in rats.

DESIGN

Twelve-week-old Sprague-Dawley rats were randomized into 4 groups: (1) a group fed an HFS diet subjected to aerobic exercise (HFS+Aer), (2) a group fed an HFS diet subjected to resistance exercise (HFS+Res), (3) a group fed an HFS diet with no exercise (HFS+Sed), and (4) a chow-fed sedentary control group (Chow+Sed). HFS+Sed animals were heavier and had greater body fat, higher levels of triglycerides and total cholesterol, and more joint damage than Chow+Sed animals.

RESULTS

The HFS+Res group had higher body mass and body fat than Chow+Sed animals and higher OA scores than animals from the HFS+Aer group. Severe bone lesions were observed in the HFS+Sed and Chow+Sed animals at age 24 weeks, but not in the HFS+Res and HFS+Aer group animals.

CONCLOSION

In summary, aerobic training provided better protection against knee joint OA than resistance training in this rat model of HFS-diet-induced obesity. Exposing rats to exercise, either aerobic or resistance training, had a protective effect against the severe bone lesions observed in the nonexercised rats.

Clinical effect of aerobic exercise training in chronic obstructive pulmonary disease: A retrospective study

Aerobic exercise training is a kind of pulmonary rehabilitation for lung diseases. This was a retrospective study to assess the efficacy of aerobic exercise training in chronic obstructive pulmonary disease (COPD) at a stable stage. A total of one hundred and fifty-six stable COPD patients who had accepted self-education only or self-education combined with an aerobic exercise training between January 2017 to January 2019 were reviewed retrospectively. A total of 79 patients who had received self-education combined with an aerobic exercise training schedule comprised the aerobic exercise training group (AET group) and 77 patients who had received self-education only were regarded as the education group (EDU group). The acute incidence rate in AET group was 7.6% better than that in EDU group 20.7% (P < .05). The AET group patients expressed higher levels of 6 minutes walking distance (6MWD) (P < .05) and better evaluations of both lung function (P < .05) and T lymphocyte immune response (P < .05), as well as significantly decreased chronic obstructive pulmonary disease assessment test (CAT) scores and modified British medical research council (mMRC) grades (P < .05). Patients in EDU group did not report any changes in any of these characteristics. The aerobic exercise training intervention contributed to an increasing in 6MWD and decrease in CAT scores and mMRC grades, as well as improving the T lymphocyte immune response in stable COPD patients.

trans 10, cis 12, but Not cis 9, trans 11 Conjugated Linoleic Acid Isomer Enhances Exercise Endurance by Increasing Oxidative Skeletal Muscle Fiber Type via Toll-like Receptor 4 Signaling in Mice

Conjugated linoleic acid (CLA) has been implicated in regulating muscle fiber. However, which isomer elicits this effect and the underlying mechanisms remain unclear. Here, male C57BL6/J mice and C2C12 cells were treated with two CLA isomers, and the exercise endurance, skeletal muscle fiber type, and involvement of Toll-like receptor 4 (TLR4) signaling were assessed. The results demonstrated that dietary t10, c12, but not c9, t11-CLA isomer enhanced exercise endurance of mice (from 115.88 ± 11.21 to 130.00 ± 15.84 min, P < 0.05) and promoted the formation of oxidative muscle fiber type of gastrocnemius muscle (from 0.15 ± 0.04 to 0.24 ± 0.05, P < 0.05). Consistently, t10, c12-CLA isomer increased the mRNA expression of oxidative muscle fiber type in C2C12 myotubes (from 1.00 ± 0.08 to 2.65 ± 1.77, P < 0.05). In addition, t10, c12-CLA isomer increased TLR4 signaling expression in skeletal muscle and C2C12 myotubes. More importantly, knockdown of TLR4 eliminated the t10, c12-CLA isomer-induced enhancement of exercise endurance in mice and elevation of oxidative muscle fiber type in C2C12 myotubes and gastrocnemius muscle. Together, these findings showed that t10, c12, but not c9, t11-CLA isomer enhances exercise endurance by increasing oxidative skeletal muscle fiber type via TLR4 signaling.

Consumption of a high-fat-high-sucrose diet partly diminishes mechanical and structural adaptations of cardiac muscle following resistance training

[Purpose]

The purpose of this study was to investigate the effects of a high-fat high-sucrose (HFHS) diet on previously reported adaptations of cardiac morphological and contractile properties to resistance training.

[Methods]

Twelve-week-old rats participated in 12-weeks of resistance exercise training and consumed an HFHS diet. Echocardiography and skinned cardiac muscle fiber bundle testing were performed to determine the structural and mechanical adaptations.

[Results]

Compared to chow-fed sedentary animals, both HFHS- and chow-fed resistance-trained animals had thicker left ventricular walls. Isolated trabecular fiber bundles from chow-fed resistance-trained animals had greater force output, shortening velocities, and calcium sensitivities than those of chow-fed sedentary controls. However, trabeculae from the HFHS resistance-trained animals had greater force output but no change in unloaded shortening velocity or calcium sensitivity than those of the chow-fed sedentary group animals.

[Conclusion]

Resistance exercise training led to positive structural and mechanical adaptations of the heart, which were partly offset by the HFHS diet.