The effect of long-term ultra-endurance exercise and SOD2 genotype on telomere shortening with age

Aging Processes Are Affected by Energy Balance: Focused on the Effects of Nutrition and Physical Activity on Telomere Length

PURPOSE OF REVIEW

The number and proportion of individuals aged 60 and over are increasing globally. The increase in the elderly population has important social and economic effects. Telomere length is an important marker for healthy aging. Here, we review the relevance between telomere length and energy balance by determining the effects of physical activity, nutrients, dietary patterns, and foods on healthy aging and telomere length with related studies.

RECENT FINDINGS

Evidence emphasizes the importance of telomere length and integrity for healthy aging. It also focuses on the importance of potential interventions such as physical activity and a healthy diet to improve this process. We suggest that ensuring energy balance with regular physical activity and healthy diets can contribute to the aging process by protecting telomere length. In addition, different methods in studies, short and inconsistent durations, different types of exercise, different diet patterns, and non-standard foods have led to conflicting results. More studies are needed to elucidate molecular-based mechanisms.

Physical Activity on Telomere Length as a Biomarker for Aging: A Systematic Review

Background

Overall life expectancy continues to rise, approaching 80 years of age in several developed countries. However, healthy life expectancy lags far behind, which has, in turn, contributed to increasing costs in healthcare. One way to improve health and attenuate the socio-economic impact of an aging population is to increase overall fitness through physical activity. Telomere attrition or shortening is a well-known molecular marker in aging. As such, several studies have focused on whether exercise influences health and aging through telomere biology. This systematic review examines the recent literature on the effect of physical activity on telomere length (TL) and/or telomerase activity as molecular markers of aging.

Methods

A focused search was performed in the databases PubMed and Web of Science for retrieving relevant articles over the past ten years. The search contained the following keywords: exercise, sport, physical activity, fitness, sedentary, physical inactivity, telomere, telomere length, t/s ratio, and telomerase. PRISMA guidelines for systematic reviews were observed.

Results

A total of 43 articles were identified and categorized into randomized controlled trials (RCT), observational or interventional studies. RCTs (n = 8) showed inconsistent findings of increased TL length with physical activity in, e.g. obese, post-menopausal women. In comparison with a predominantly sedentary lifestyle, observational studies (n = 27) showed significantly longer TL with exercise of moderate to vigorous intensity; however, there was no consensus on the duration and type of physical activity and training modality. Interventional studies (n = 8) also showed similar findings of significantly longer TL prior to exercise intervention; however, these studies had smaller numbers of enrolled participants (mostly of high-performance athletes), and the physical activities covered a range of exercise intensities and duration. Amongst the selected studies, aerobic training of moderate to vigorous intensity is most prevalent. For telomere biology analysis, TL was determined mainly from leukocytes using qPCR. In some cases, especially in RCT and interventional studies, different sample types such as saliva, sperm, and muscle biopsies were analyzed; different leukocyte cell types and potential genetic markers in regulating telomere biology were also investigated.

Conclusions

Taken together, physical activity with regular aerobic training of moderate to vigorous intensity appears to help preserve TL. However, the optimal intensity, duration of physical activity, as well as type of exercise still need to be further elucidated. Along with TL or telomerase activity, participants’ fitness level, the type of physical activity, and training modality should be assessed at different time points in future studies, with the plan for long-term follow-up. Reducing the amount of sedentary behavior may have a positive effect of preserving and increasing TL. Further molecular characterization of telomere biology in different cell types and tissues is required in order to draw definitive causal conclusions on how physical activity affects TL and aging.

Influence of the SOD2 A16V gene polymorphism on alterations of redox markers and erythrocyte membrane fatty acid profiles in patients with multiple chemical sensitivity

Chronically increased oxidative stress has been reported in patients with multiple chemical sensitivity (MCS). Recently, a single nucleotide polymorphism of the gene coding for mitochondrial superoxide dismutase (SOD2), namely the missense substitution A16V (C47>T) resulting in alteration of SOD2 enzyme activity, has been reported to be associated with MCS. However, the influence of SOD2 A16V genetic background on redox status of patients with MCS has not yet been investigated. Here, the results of a retrospective analysis aimed to evaluate the role of the SOD2 A16V polymorphism in the alterations of antioxidant defense markers as well as fatty acid (FA) composition of erythrocyte membranes in 67 patients with MCS matched with 55 healthy controls is reported. The mutated SOD2 V16 variant was observed more frequently in the MCS group compared with the control group, and this difference was statistically significant. The most common genotype in both groups was the heterozygous SOD2 AV16 variant, whereas the mutated SOD2 VV16 variant was more frequently observed in the MCS group, although the difference was not significant. The MCS cohort showed significantly depleted levels of plasma total antioxidant activity, ubiquinol, erythrocyte reduced glutathione and membrane polyunsaturated FA levels, coupled with significant increases in glutathione peroxidase activity, likely accounting for sustained detoxification from lipoperoxides. Notably, the highest levels of oxidative stress were found in patients with MCS bearing the genotype SOD2 AA16, whereas intermediate levels were found in patients bearing the heterozygous AV16 genotype. Healthy subjects bearing the SOD2 AA16 genotype also showed increased oxidative stress compared with carriers of other SOD2 genotypes. Despite the need for further confirmations in larger cohorts, due to MCS population genetic heterogeneity, these preliminary findings suggest that SOD2 defective activity makes certain patients with MCS more susceptible to developing oxidative stress following a chronic daily exposure to pro-oxidant insults.

Comparison of Telomere Length in Young and Master Endurance Runners and Sprinters

It is unclear how running modality influences telomere length (TL). This single laboratory visit study compared the TL of master sprinters and endurance runners with their young counterparts. The correlation between leukocyte and buccal cell TL in athletes was also explored. Participants consisted of 11 young controls, 11 young sprinters, 12 young endurance runners, 12 middle-aged controls, 11 master sprinters, and 12 master endurance runners. Blood and buccal samples were collected and randomized for analysis of TL by quantitative polymerase chain reaction. Young endurance runners displayed longer telomeres than master athletes (p < .05); however, these differences were not significant when controlled for covariates (p > .05). A positive correlation existed between leukocyte and buccal cell TL in athletes (r = .567, p < .001). In conclusion, young endurance runners possess longer telomeres than master endurance runners and sprinters, a consequence of lower body mass index and visceral fat.

Elite swimmers possess shorter telomeres than recreationally active controls

PURPOSE

Elite athletes are reported to possess longer telomeres than their less active counterparts. ACE gene (Insertion/Deletion) polymorphism has been previously associated with elite athletic performance, with the deletion (D) variant appearing more frequently in short distance swimmers. Additionally, the D allele has been reported to have a negative effect on telomere length. The aim of this study was to investigate the telomere length of elite swimmers and its potential association with ACE genotype.

METHODS

Telomere length was measured by real-time quantitative PCR and ACE I/D genotypes analysed by standard PCR and electrophoresis in 51 young elite swimmers and 56 controls.

RESULTS

Elite swimmers displayed shorter telomeres than controls (1.043 ± 0.127 vs 1.128 ± 0.177, p = 0.006). When split by sex, only elite female swimmers showed significantly shorter telomeres than their recreationally active counterparts (p = 0.019). ACE genotype distribution and allelic frequency did not differ between elite swimmers and controls, or by event distance among elite swimmers only. No association was observed between telomere length and ACE genotype in the whole cohort.

CONCLUSIONS

Elite swimmers possessed shorter telomeres than recreationally active controls. Our findings suggesting a negative effect of high-level swimming competition and/or training on telomere length and subsequent biological aging, particularly in females. However, this significant difference in telomere length does not appear to be attributed to the D allele as we report a lack of association between telomere length and ACE genotype frequency in elite swimmers and controls.