Associations Among Physical Activity Level and Skeletal Muscle Antioxidants in Older Adults

Impacts of Resistance Training on Endogenous Antioxidants in Older Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Cellular antioxidant activity and oxidative stress are assumed to be critical factors in the aging process. This study aims to investigate the effects of resistance training (RT) on endogenous antioxidants in healthy older individuals.

DESIGN

The records were identified through searches in 5 electronic databases (PubMed, Bireme, Scopus, SPORTDiscus, and Web of Science) in June 2024 for eligible randomized controlled trials that observed older individuals subjected to RT programs that reported endogenous antioxidant outcomes. The Tool for the assEssment of Study qualiTy and reporting in EXercise (ranging from 0 to 15) was used to verify the methodological quality of the studies.

RESULTS

Fourteen randomized controlled trials involving 676 healthy older individuals were included in the systematic review. Of these, 10 articles were included in the meta-analysis. The meta-analysis indicated that RT interventions did not have significant effects on improving catalase levels (standardized mean difference = 0.84; 95% CI, -0.61 to 2.29) or antioxidant activity (standardized mean difference = 0.28; 95% CI, -0.41 to 0.98). However, RT was associated with a significant reduction in superoxide dismutase (mean difference = -0.16; 95% CI, -0.29 to -0.04) and glutathione peroxidase increased (standardized mean difference = 0.57; 95% CI, 0.13 to 1.01).

CONCLUSIONS

Based on available evidence, the meta-analysis suggests potential improvement in glutathione peroxidase gene expression and reduction in gene expression of superoxide dismutase after the intervention physical activity intervention in healthy older individuals.

Exercise-induced Nrf2 activation increases antioxidant defenses in skeletal muscles

Following the discovery that exercise increases the production of reactive oxygen species in contracting skeletal muscles, evidence quickly emerged that endurance exercise training increases the abundance of key antioxidant enzymes in the trained muscles. Since these early observations, knowledge about the impact that regular exercise has on skeletal muscle antioxidant capacity has increased significantly. Importantly, in recent years, our understanding of the cell signaling pathways responsible for this exercise-induced increase in antioxidant enzymes has expanded exponentially. Therefore, the goals of this review are: 1) summarize our knowledge about the influence that exercise training has on the abundance of key antioxidant enzymes in skeletal muscles; and 2) to provide a state-of-the-art review of the nuclear factor erythroid 2-related factor (Nrf2) signaling pathway that is responsible for many of the exercise-induced changes in muscle antioxidant capacity. We begin with a discussion of the sources of reactive oxygen species in contracting muscles and then examine the exercise-induced changes in the antioxidant enzymes that eliminate both superoxide radicals and hydrogen peroxide in muscle fibers. We conclude with a discussion of the advances in our understanding of the exercise-induced control of the Nrf2 signaling pathway that is responsible for the expression of numerous antioxidant proteins. In hopes of stimulating future research, we also identify gaps in our knowledge about the signaling pathways responsible for the exercise-induced increases in muscle antioxidant enzymes.

Effects of Endurance Training on Antioxidant and Hormonal Status in Peripheral Blood of Young Healthy Men

(1) Background: Physical activity may cause an imbalance in the major functions of the human body. This study aimed to investigate the effects of endurance running training on the parameters of the antioxidant defense system (SOD, CAT, GPx, GR, GSH), LPO (malondialdehyde, MDA), and stress hormones (A, NA) in young healthy, previously untrained men. (2) Methods: The training program was as follows: 8 weeks of running, three times per week; the duration of a single session was 30-70 min, the intensity was twice a week in the so-called extensive endurance zone, and once a week in the anaerobic threshold zone. Blood samples were collected from the subjects, before and after the running program. (3) Results: The training program resulted in a significant increase in maximal oxygen consumption (p < 0.001). The activities of SOD, GPx, and GR also increased significantly (p < 0.05, p < 0.01, and p < 0.05, respectively), while CAT activity and GSH and MDA concentrations remained unchanged. The concentration of A decreased (p < 0.05), while the NA concentration increased significantly (p < 0.05). SOD, GPx, GR, and NA positively correlated with VO2max (p < 0.05, p < 0.001, p < 0.01, p < 0.05, respectively), while a negative correlation was detected between A and VO2max (p < 0.05). (4) Conclusions: These results indicate that there is no persistent oxidative stress in response to the applied 8-week running program, probably due to exercise-induced protective alterations in the antioxidant defense system. Furthermore, adaptations occurred at the hormonal level, making the organism more ready for a new challenge.

Exercise Training and Skeletal Muscle Antioxidant Enzymes: An Update

The pivotal observation that muscular exercise is associated with oxidative stress in humans was first reported over 45 years ago. Soon after this landmark finding, it was discovered that contracting skeletal muscles produce oxygen radicals and other reactive species capable of oxidizing cellular biomolecules. Importantly, the failure to eliminate these oxidant molecules during exercise results in oxidation of cellular proteins and lipids. Fortuitously, muscle fibers and other cells contain endogenous antioxidant enzymes capable of eliminating oxidants. Moreover, it is now established that several modes of exercise training (e.g., resistance exercise and endurance exercise) increase the expression of numerous antioxidant enzymes that protect myocytes against exercise-induced oxidative damage. This review concisely summarizes the impact of endurance, high-intensity interval, and resistance exercise training on the activities of enzymatic antioxidants within skeletal muscles in humans and other mammals. We also discuss the evidence that exercise-induced up-regulation of cellular antioxidants reduces contraction-induced oxidative damage in skeletal muscles and has the potential to delay muscle fatigue and improve exercise performance. Finally, in hopes of stimulating further research, we also discuss gaps in our knowledge of exercise-induced changes in muscle antioxidant capacity.

Activity of erythrocyte antioxidant enzymes in healthy women depends on age, BMI, physical activity, and diet

Introduction

Antioxidant enzymes protect the human body against the harmful effects of oxidative stress. The activity of antioxidant enzymes changes with age and depends on dietary nutrients such as fats and vitamins, which can have a significant impact on minimizing or exacerbating oxidative stress.

Aim

To examine the effect of age, BMI, diet, physical activity, and smoking status on the activity of erythrocyte antioxidant enzymes catalase, glutathione reductase, glutathione peroxidase glutathione S-transferase, superoxide dismutase, and glutathione concentrations in healthy women.

Material and methods

This study included 98 healthy women aged between 20 and 65 years. All women underwent anthropometric tests: body weight, height, hip, and waist circumference. Antioxidant activity in erythrocytes was measured by spectrophotometric methods.

Results

Catalase activity increased significantly with age (p < 0.001), while superoxide dismutase activities and glutathione decreased with age (p = 0.008, p = 0.023, respectively). Women with a lower BMI (emaciation) had higher superoxide dismutase activity than those in the first degree of obesity (p = 0.009).

Conclusions

(1) Increased catalase activity with age may signify a large amount of hydrogen peroxide resulting from malfunctioning antioxidant systems in old age. (2) A decline in superoxide dismutase activity with age may indicate inactivation of this enzyme, inappropriate SOD function in the presence of excessive amounts of hydrogen peroxide, and glycation of superoxide dismutase molecules. (3) A negative correlation between superoxide dismutase activity and the BMI index may indicate a decreased enzymatic activity in obese people.