Effects of resistance exercise training on redox homeostasis in older adults. A systematic review and meta-analysis

Effectiveness of Whey Protein Supplementation during Resistance Exercise Training on Skeletal Muscle Mass and Strength in Older People with Sarcopenia: A Systematic Review and Meta-Analysis

OBJECTIVE

To determine the effectiveness of whey protein (WP) supplementation during resistance exercise training (RET) vs. RET with or without placebo supplementation on skeletal muscle mass, strength, and physical performance in older people with Sarcopenia.

METHODS

Electronic searches in the PubMed, Embase, Scopus, Web of Science, LILACS, SPORTDiscus, Epistemonikos, and CINAHL databases were performed until 20 January 2023. Randomized clinical trials conducted on sarcopenic adults aged 60 or older were included. The studies had to compare the effectiveness of the addition of supplements based on concentrated, isolated, or hydrolyzed whey protein during RET and compare it with RET with or without placebo supplementation on skeletal muscle mass and strength changes. The study selection process, data extraction, and risk of bias assessment were carried out by two independent reviewers.

RESULTS

Seven randomized clinical trials (591 participants) were included, and five of them provided data for quantitative synthesis. The overall pooled standardized mean difference (SMD) estimate showed a small effect size in favor of RET plus WP for skeletal muscle mass according to appendicular muscle index, with statistically significant differences compared with RET with or without the placebo group (SMD = 0.24; 95% CI, 0.05 to 0.42; p = 0.01; I2 = 0%, p = 0.42). The overall pooled mean difference (MD) estimate showed a significant difference of +2.31 kg (MD = 2.31 kg; 95% CI, 0.01 to 4.6; p = 0.05; I2 = 81%, p < 0.001) in handgrip strength in the RET plus WP group compared with the RET group with or without placebo. The narrative synthesis revealed discordance between the results of the studies on physical performance.

CONCLUSIONS

WP supplementation during RET is more effective in increasing handgrip strength and skeletal muscle mass in older people with Sarcopenia compared with RET with or without placebo supplementation. However, the effect sizes were small, and the MD did not exceed the minimally important clinical difference. The quality of the evidence was low to very low according, to the GRADE approach. Further research is needed in this field.

Redox-based disruption of cellular hormesis and promotion of degenerative pathways: perspectives on ageing processes

The present work aims to link the redox and cell-centric theories of chronic processes in human biology, focusing on ageing. A synthetic overview of cellular redox pathways will be integrated by the concept of hormesis, which disruption leads to several physiopathological processes. The onset of age-related diseases due to the restriction of homeodynamic capacity will be herein considered in a redox fashion. Up-to-date arguments on hormetic agents, such as geroprotectors, dietary interventions, and physical exercise are refining the presented theoretical framework, integrated by insights from extracellular vesicles, microbiota, pollutants, and timing mechanisms. The broad concepts of exposome encompass the redox-based alteration of cellular hormesis for providing meaningful perspectives on redox biogerontology.

Antioxidative properties of phenolic compounds and their effect on oxidative stress induced by severe physical exercise

Extensive research has found strongly increased generation of reactive oxygen species, free radicals, and reactive nitrogen species during acute physical exercise that can lead to oxidative stress (OS) and impair muscle function. Polyphenols (PCs), the most abundant antioxidants in the human diet, are of increasing interest to athletes as antioxidants. Current literature suggests that antioxidants supplementation can effectively modulate these processes. This overview summarizes the actual knowledge of chemical and biomechanical properties of PCs and their impact as supplements on acute exercise-induced OS, inflammation control, and exercise performance. Evidence maintains that PC supplements have high potency to positively impact redox homeostasis and improve skeletal muscle's physiological and physical functions. However, many studies have failed to present improvement in physical performance. Eleven of 15 representative experimental studies reported a reduction of severe exercise-induced OS and inflammation markers or enhancement of total antioxidant capacity; four of eight studies found improvement in exercise performance outcomes. Further studies should be continued to address a safe, optimal PC dosage, supplementation timing during a severe training program in different sports disciplines, and effects on performance response and adaptations of skeletal muscle to exercise.

Dose- and Intensity-Response Associations Between Leisure-Time Physical Activity and Markers of Inflammation and Oxidative Stress in Older Adults

This study aimed to investigate the dose- and intensity-response associations between leisure-time physical activity (LTPA) and markers of inflammation and oxidative stress in older adults. Multivariable linear regression was performed to evaluate the associations among 3,559 older adults in 2015-2018 National Health and Nutrition Examination Survey. LTPA was negatively associated with inflammatory markers including C-reactive protein, segmented neutrophil count and alkaline phosphatase, and positively associated with one marker of antioxidants albumin in older adults. Compared with vigorous LTPA, moderate LTPA could provide more benefits through further decreasing white blood cell count and alkaline phosphatase, and increasing serum bilirubin and albumin. The effects of LTPA on C-reactive protein and albumin were more significant in participants with chronic diseases including diabetes, hypertension, and cancer. In conclusion, this study demonstrates the dose- and intensity-response effects of LTPA on inflammation and oxidative stress and provides exercise prescription recommendations for older adults.

Effect of Physical Exercise Under Different Intensity and Antioxidative Supplementation for Plasma Superoxide Dismutase in Healthy Adults: Systematic Review and Network Meta-Analysis

Background

The dynamic balance between oxidation and anti-oxidation in the body’s internal environment has a significant meaning for human health. Physical exercise and antioxidative supplementation could affect the balance of oxidation and anti-oxidation systems. The evidence on the effects of physical exercise and antioxidative supplementation is mixed.

Aims

To identify the effects of physical exercise, antioxidative supplementation, and their combination on the dynamic balance between oxidation and anti-oxidation in different subgroups of healthy adults.

Methods

All studies which reported randomized controlled trials with healthy participants were screened and included from the databases of PubMed, Medline, Embase, and Ovid. All participants were reclassified according to their different daily life activities. All physical exercise interventions were reclassified according to the intensity. The effect size would be calculated in percent or factor units from the mean level change with its associated random-effect variance.

Result

There were 27 studies included in this review. The agreement between authors by using The Cochrane Collaboration Risk of Bias Assessment Tool reached a kappa-value of 0.72. Maintaining a regular physical exercise routine in an appropriate intensity would be beneficial to the body’s anti-oxidative potential. Anti-oxidative supplementation could have some positive but limited effects on the body’s anti-oxidative status and complex interaction with physical exercise.

Conclusion

Keeping a regular physical exercise routine and gradually increasing its intensity according to the individual’s daily life activity might be a better choice to maintain and enhancing the body’s antioxidation potential, only using anti-oxidative supplementation is not recommended. More research is needed to explore the best combination protocol.

Registration Number

CRD42021241995.

Active Life for Brain Health: A Narrative Review of the Mechanism Underlying the Protective Effects of Physical Activity on the Brain

A growing body of evidence clearly indicates the beneficial effects of physical activity (PA) on cognition. The importance of PA is now being reevaluated due to the increase in sedentary behavior in older adults during the COVID-19 pandemic. Although many studies in humans have revealed that PA helps to preserve brain health, the underlying mechanisms have not yet been fully elucidated. In this review, which mainly focuses on studies in humans, we comprehensively summarize the mechanisms underlying the beneficial effects of PA or exercise on brain health, particularly cognition. The most intensively studied mechanisms of the beneficial effects of PA involve an increase in brain-derived neurotrophic factor (BDNF) and preservation of brain volume, especially that of the hippocampus. Nonetheless, the mutual associations between these two factors remain unclear. For example, although BDNF presumably affects brain volume by inhibiting neuronal death and/or increasing neurogenesis, human data on this issue are scarce. It also remains to be determined whether PA modulates amyloid and tau metabolism. However, recent advances in blood-based biomarkers are expected to help elucidate the beneficial effects of PA on the brain. Clinical data suggest that PA functionally modulates cognition independently of neurodegeneration, and the mechanisms involved include modulation of functional connectivity, neuronal compensation, neuronal resource allocation, and neuronal efficiency. However, these mechanisms are as yet not fully understood. A clear understanding of the mechanisms involved could help motivate inactive persons to change their behavior. More accumulation of evidence in this field is awaited.

Exercise-induced oxidative stress and melatonin supplementation: current evidence

Melatonin possesses the indoleamine structure and exerts antioxidant and anti-inflammatory actions and other physiological properties. Physical exercise can influence secretion of melatonin. Melatonin is used as a natural supplement among athletes to regulate sleep cycles and protect muscles against oxidative damage. Despite decades of research, there is still a lack of a comprehensive and critical review on melatonin supplementation and physical activity relationship. The aim of this literature review is to examine the antioxidant, anti-inflammatory and other biological functions played by melatonin with reference to the effect of physical exercise on melatonin secretion and the effect of this compound supplementation on exercise-induced oxidative stress in athletes. Evidence shows that intense exercises disturb antioxidant status of competitive athletes, whereas supplementation with melatonin strengthens antioxidant status in trained athletes in various sports as the compound showed high potency in reduction of the oxidative stress and inflammation markers generated during intense and prolonged exercise.

Effects of Resistance Training on the Redox Status of Skeletal Muscle in Older Adults

The aim of this study was to investigate the effects of resistance training (RT) on the redox status of skeletal muscle in older adults. Thirteen males aged 64 ± 9 years performed full-body RT 2x/week for 6 weeks. Muscle biopsies were obtained from the vastus lateralis prior to and following RT. The mRNA, protein, and enzymatic activity levels of various endogenous antioxidants were determined. In addition, skeletal muscle 4-hydroxynonenal and protein carbonyls were determined as markers of oxidative damage. Protein levels of heat shock proteins (HSPs) were also quantified. RT increased mRNA levels of all assayed antioxidant genes, albeit protein levels either did not change or decreased. RT increased total antioxidant capacity, catalase, and glutathione reductase activities, and decreased glutathione peroxidase activity. Lipid peroxidation also decreased and HSP60 protein increased following RT. In summary, 6 weeks of RT decreased oxidative damage and increased antioxidant enzyme activities. Our results suggest the older adult responses to RT involve multi-level (transcriptional, post-transcriptional, and post-translational) control of the redox status of skeletal muscle.

Exercise rescues mitochondrial coupling in aged skeletal muscle: a comparison of different modalities in preventing sarcopenia

Skeletal muscle aging is associated with a decline in motor function and loss of muscle mass- a condition known as sarcopenia. The underlying mechanisms that drive this pathology are associated with a failure in energy generation in skeletal muscle, either from age-related decline in mitochondrial function, or from disuse. To an extent, lifelong exercise is efficacious in preserving the energetic properties of skeletal muscle and thus may delay the onset of sarcopenia. This review discusses the cellular and molecular changes in skeletal muscle mitochondria during the aging process and how different exercise modalities work to reverse these changes. A key factor that will be described is the efficiency of mitochondrial coupling—ATP production relative to O₂ uptake in myocytes and how that efficiency is a main driver for age-associated decline in skeletal muscle function. With that, we postulate the most effective exercise modality and protocol for reversing the molecular hallmarks of skeletal muscle aging and staving off sarcopenia. Two other concepts pertinent to mitochondrial efficiency in exercise-trained skeletal muscle will be integrated in this review, including- mitophagy, the removal of dysfunctional mitochondrial via autophagy, as well as the implications of muscle fiber type changes with sarcopenia on mitochondrial function.