The importance of physical training in the treatment of PCOS needs to be clarified. In the present study we did not observe differences in telomere length after the CAT and IAT training protocols, with no changes in the inflammatory biomarkers’ homocysteine and C-reactive protein. Despite no differences in telomere length and inflammation, the CAT protocol reduced the hormonal level of total testosterone, total cholesterol, and LDL, while also improving anthropometric indexes, decreasing WC and HC. The IAT, on the other hand, showed a decrease in total testosterone and FAI, and a reduction in WC and WHR. The non-training CG’s total cholesterol was reduced; however, the WC and body fat percentage were increased after non-intervention observational period. Considering the evaluation of structured aerobic physical training protocols in PCOS women, most studies are transversal and unsupervised, and the effects of physical training on telomere length may not be representative.
To our knowledge, few studies investigate changes on telomere length in PCOS, and the results are controversial leading to ambiguous conclusions, probably due to the heterogeneity of this syndrome. The first study was carried out by Li et al (2014) and the authors observed leukocytes telomere shortening in PCOS women. Then, we reported no alterations in leukocyte’s telomere length from PCOS, however, a negative correlation of inflammatory biomarkers with telomere length was observed. In agreement, Wei et al. (2017) did not find changes in telomere length in leukocytes of PCOS women. Contradictorily, an increasing in leukocytes’ telomeres from women with PCOS was reported by Wang et al. (2017). The authors also reported a reduction of the TERRA (Telomeric repeat-containing RNA) gene expression that was negatively correlated with testosterone, whereas, telomere length had a positive correlation with testosterone.
We previously reported that physical resistance training (PRT) improved hyperandrogenism, reproductive function, and body composition in women with PCOS, with no changes on BMI or metabolic parameters of PCOS. The PRT was performed three times per week during a four-week period in PCOS and non-PCOS women. We also observed that PRT reduced telomere length and increased homocysteine level in all participants, irrespective of them having PCOS or not. Considering aging and senescence, the PRT should be practiced with caution. In addition, a positive correlation between androstenedione and telomere length was observed in PCOS, suggesting that the hyperandrogenism may be an important protective factor for telomere erosion, irrespective of metabolic disturbance that contribute to telomere shortening in PCOS. Short term PRT seems to change telomere content, however the same period of continuous or intermittent aerobic training did not affect telomere biology.
Loprinzi and Sng (2016) evaluated the effect of nine types of unsupervised exercise on telomere length and suggested that running was the most effective exercise with positive impacts on telomere biology. In young and elderly populations, the endurance exercise practice increases maximum aerobic capacity (VO2max) that consequently increases telomere length[14, 29]. Unfortunately, we did not measure the VO2max in our groups. Tucker (2017) evaluated the metabolic equivalent (MET), the ratio of the work metabolic rate, to the resting metabolic rate, using frequency, intensity and duration, observed that higher level of physical activity meant longer telomeres were reported in men and women. Differently, shortening of telomeres in endurance athletes after exposure to acute exercise was observed, due to oxidative damage in DNA.
Physical exercise can improve the cardiometabolic profile in women with PCOS without weight loss. High intensity interval training reduced insulin resistance and body composition in women with PCOS, whereas resistance training improved the body composition, and these improvements were independent of weight loss. We also investigated the effects of aerobic exercise on metabolic, hormonal and anthropometric parameters which also may interfere in telomere biology. Both CAT and IAT showed benefits to women with PCOS, decreasing total testosterone level and anthropometric indexes in PCOS women, even though only CAT reduced lipids parameters. Mario et al. (2017) reported that habitual physical activity improves anthropometric parameters and hyperandrogenism in women with PCOS. According to non-supervised data, intense physical activity reduces metabolic syndrome in PCOS, irrespective of age, BMI, or total energy expenditure.
As a molecular marker of aging, progressive telomere shortening with each cell division is a common biological process, leading to chromosomal instability and cell senescence or apoptosis. Age-related diseases and some metabolic alterations might contribute to an accelerated shortening of telomeres  while others conditions, as increased estrogens levels  and physical activity prevent against progressive telomeric loss . As reported in this study, Mason et al. (2013) did not observe changes on telomere biology after aerobic physical exercise, and maybe the time of exposition was relatively shorter to observe changes in telomere length . Since telomere changes are progressive and a relatively slow process (~52 base pair/year) , 16 weeks of intervention may be not sufficient to observe the effect of the aerobic intervention on telomere biology. Sanberoth et al. (2015) suggested that at least 10 years of regular physical activity will be necessary for improvements on telomeres, that may explain our results, since four months of CAT or IAT might be insufficient to observe differences on telomere biology, and an increase in exposure time might provide additional information. Despite no differences in telomeres, in the non-obese population, physical exercise may prevent telomere shortening [14, 29].
In the adjusted model of our data, none of the confoundable variables seemed to interfere in telomere length in PCOS. However, a negative correlation was observed between telomere length and age, as expected, and the obesity index BMI and WC and the inflammatory biomarkers CRP and homocystein. A cross-sectional meta-analysis of 87 observational studies reported that telomere length is negatively correlated with BMI, since higher BMI is related with reduced telomeres, and this association appeared to be stronger in the young individuals. This negative correlation may be due to the increased inflammation and oxidative stress, a common characteristic of PCOS that is positively correlated with BMI. Nevertheless, the inflammatory biomarkers did not change after aerobic exercises, but a negative correlation with telomere length was observed in PCOS as previously reported . Increased WC is related to reduced telomeres in obese women and physical activity is an important strategy for obesity treatment, by reducing anthropometric indices and improving body composition [35, 41]. Since booth exercises reduced WC and hyperandrogenism in our BMI randomized study, the differences in telomere length might not be observed in a short time of training. Associated with the well-controlled study, as a repetitive molecular marker, telomeres have a great variability
Despite the important findings of this manuscript, one of the limitations of our clinical trial is that we used a platform chemiluminescence for the measurement of steroid sex hormones, which may not be as sensitive as mass spectrometry for detecting androgen levels in women. Still, we did not control the diet of the participants or evaluated the levels of habitual physical activity related to work and leisure. It’s important to consider that intensity of the protocols was defined in terms of HRmax (%). Although the literature shows which there is a linear relationship between VO2max and HRmax at submaximal exercise intensities, the VO2max (%) or metabolic equivalent (METS) are considerate the gold standard to determine exercise intensity (19). It´s may have underestimated the intensity. However, in this controlled clinical trial study the effect of aerobic physical exercises evaluated were supervised by a physical education professional, which strengthens our results.