kinase with the number of sprints. 8 However, no single biomarker was exclusively able to cover all aspects of player load or recovery status. 4 , 7 In this respect, cell-free, circulating DNA (cfDNA) seems to be a promising approach. Low concentrations of cfDNA can be detected in healthy subjects
Nils Haller, Tobias Ehlert, Sebastian Schmidt, David Ochmann, Björn Sterzing, Franz Grus and Perikles Simon
Michely V. Andreatta, Victor M. Curty, João Victor S. Coutinho, Miguel Ângelo A. Santos, Paula F. Vassallo, Nuno F. de Sousa and Valério G. Barauna
The search for an early biomarker of exercise-induced performance decrement related to muscle damage is an ongoing topic of interest by exercise physiologists, and cell-free DNA (cfDNA) in the plasma is one of the most investigated recently. Small quantities of cfDNA are found both in healthy
Stephanie Whisnant Cash, Shirley A.A. Beresford, Thomas L. Vaughan, Patrick J. Heagerty, Leslie Bernstein, Emily White and Marian L. Neuhouser
Limited evidence suggests that very high-intensity exercise is positively associated with DNA damage but moderate exercise may be associated with DNA repair.
Participants were 220 healthy, Washington State 50- to 76-year-olds in the validity/biomarker substudy of the VITamins And Lifestyle (VITAL) cohort, who provided blood samples and completed questionnaires assessing recent physical activity and demographic and health factors. Measures included nested activity subsets: total activity, moderate- plus high-intensity activity, and high-intensity activity. DNA damage (n = 122) and repair (n = 99) were measured using the comet assay. Multivariate linear regression was used to estimate regression coefficients and associated 95% confidence intervals (CIs) for relationships between MET-hours per week of activity and each DNA outcome (damage, and 15- and 60-minute repair capacities).
DNA damage was not associated with any measure of activity. However, 60-minute DNA repair was positively associated with both total activity (β = 0.21, 95% CI: 0.0057–0.412; P = .044) and high-intensity activity (β = 0.31, 95% CI: 0.20–0.60; P = .036), adjusting for age, sex, BMI, and current multivitamin use.
This study is the first to assess broad ranges of activity intensity levels related to DNA damage and repair. Physical activity was unrelated to DNA damage but was associated with increased repair.
G.W. Davison, C.M. Hughes and R.A. Bell
The purpose of this investigation was to determine the effects of antioxidant supplementation on DNA damage following exercise. Fourteen subjects were randomly assigned to one of two groups and required to ingest either antioxidants (400 mg α-lipoic acid, 200 mg co-enzyme Q10, 12 mg manganese, 600 mg vitamin C, 800 mg N-acetyl cysteine, 400 μg selenium, and 400 IU α-tocopherol per day) or placebos for 7 d. Exercise increased DNA damage, PS, FRAP, and LDH (P < 0.05), but not selectively between groups. LDH and PS concentration decreased 1 h post-exercise (P < 0.05), while LH concentration decreased 1 h post-exercise in the antioxidant group only (P < 0.05). The antioxidant group had a higher concentration of LH (P < 0.05), perhaps due to a selective difference between groups post-exercise (P < 0.05). The main findings of this investigation demonstrate that exhaustive aerobic exercise induces DNA damage, while anti-oxidant supplementation does not protect against damage.
J.A. Goon, A.H. Noor Aini, M. Musalmah, M.Y. Yasmin Anum, W.M. Wan Nazaimoon and W.Z. Wan Ngah
The biochemical mechanisms involving oxidative stress to explain the relationship between exercise and healthy aging are still unclear.
Tai Chi participants and matched sedentary volunteers age 45 and above were enrolled. Glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) activities; levels of DNA damage using the comet assay; and malondialdehyde (MDA) and advanced glycation end products (AGE) were determined at 0, 6, and 12 months.
Tai Chi subjects had decreased normal and increased mildly damaged DNA with elevated GPx activity after 6 months (n = 25). Plasma MDA and AGE concentrations decreased significantly after 12 months (n = 15) accompanied by increased SOD activity. This may be attributed to the hormesis effect, whereby mild induction of oxidative stress at the first 6 months of exercise resulted in stimulation of antioxidant defenses. These parameters were unchanged in the sedentary subjects in the first 6 months (n = 27) except for elevated SOD activity. After 12 months, the sedentary subjects (n = 17) had decreased normal DNA and increased severely damaged DNA with unaltered MDA and AGE levels while SOD and GPx activities were significantly elevated.
Regular Tai Chi exercise stimulated endogenous antioxidant enzymes and reduced oxidative damage markers.
Nils Haller, Suzan Tug, Sarah Breitbach, Arne Jörgensen and Perikles Simon
Increases in concentrations of circulating cell-free DNA (cfDNA) have recently been demonstrated to occur in a variety of exhausting and vigorous exercise settings. Here, the authors assessed the association of cfDNA with exercise duration and intensity in a controlled test–retest setting of a regenerative up-to-moderate-level aerobic run.
In a pretest, the lactate threshold (LT) was determined in 13 participants (range 10.8–13.4 km/h) by using a step-wise incremental running test. The speed of the 2 endurance runs was set to 9.6 km/h for 40 min; for the participants with an LT below the median (12.8 km/h; G1), this was a moderate aerobic run, and for those with an LT above the median, this was a regenerative run (G2). Capillary cfDNA, lactate, and rating of perceived exertion (RPE) were assessed before, every 10 min during, and after the runs.
During the last 30 min of the 2 runs, lactate did not increase, whereas cfDNA increased steadily (3.46-fold for G1 and 2.05-fold for G2). Intraclass correlation for cfDNA was high (r = .81, P < .0001) for all runners but higher for male participants (r = .92, P < .0001). The correlations of cfDNA and lactate with RPEs were r = .58 (P < .0001) and r = .32 (P < .05), respectively.
Both duration and level of intensity were significantly associated with accumulation of cfDNA. The correlation with RPE and the high test–retest reliability suggest that cfDNA might be applicable as a marker to monitor individual training load for aerobic and intermittent exercises. Future randomized, controlled, longitudinal training studies will have to reveal the full potential of cfDNA as an exercise-physiology marker.
Zuhal Hamurcu, Nazmi Saritas, Gulden Baskol and Nese Akpinar
The objective of the current study is to determine the effects of regular wrestling exercise oxidative DNA damage and antioxidant parameters. The findings of the current study have shown that 8-hydroxy-2’-deoxyguanosine (8-OHdG) obtained from wrestlers in basal status were significantly lower than those of sedentary (p = .001). In contrast, Nitric oxide (NO) and Paraoxonase-1 (PON1) were remarkably higher in wrestlers in basal status than those of sedentary (respectively, p = .001, p = .024). While the NO of wrestlers increased immediately after a 1.5-h exercise compared with those before exercise (p = .002), no differences was found between before and immediately after a 1.5-h exercise in 8-OHdG and PON1 (respectively, p = .777, p = .408).Statistically significant correlations were found between the NO and PON1 in the wrestlers in basal status (r = .671, p = .002). In conclusion, our study suggests that wrestling exercise for a healthy life is important in that it reduces DNA damage as well as enhancing antioxidant parameters.
Suzan Tug, Matthias Mehdorn, Susanne Helmig, Sarah Breitbach, Tobias Ehlert and Perikles Simon
Intensive exercise is known to be accompanied by a rapid release of cell-free DNA (cfDNA). The physiological significance of cfDNA release for performance diagnostics has not been studied. The authors analyzed the release of cfDNA during bicycle exercise and its correlation with physiological parameters.
Eleven male athletes performed an incremental cycling test. Venous blood was collected before and immediately after exercise and after 90 min of recovery. Since the amount of cfDNA is influenced by preanalytical parameters like DNA extraction and quantification method, the authors applied different measurement approaches based on quantitative real-time polymerase chain reaction. They compared a direct measurement procedure not requiring cfDNA extraction for a short (L1PA290) and a long fragment (L1PA2222) and a procedure for extracted cfDNA for a short (LTR570) and long fragment (LTR5323) with primers targeting the repetitive sequences L1PA2 and LTR5 in both assays, respectively.
With the exception of LTR5323, the procedures revealed significant increases of cfDNA postexercise, whereas the direct approach showed lower interindividual variance in cfDNA values. When linking cfDNA levels to parameters of exercise performance the authors observed that, especially, the measurement based on L1PA2222 correlated significantly with exercise markers. These correlations were similar to the relationship of the performance markers among themselves.
cfDNA is a possible physiological marker to assess and predict exercise performance in athletes. In addition, the results indicate that using cfDNA as a marker in exercise physiology requires careful selection of a suitable measurement technique, whether it is eluted DNA or directly quantified.
Carlos A. Muniesa, Zoraida Verde, Germán Diaz-Ureña, Catalina Santiago, Fernando Gutiérrez, Enrique Díaz, Félix Gómez-Gallego, Helios Pareja-Galeano, Luisa Soares-Miranda and Alejandro Lucia
Growing evidence suggests that regular moderate-intensity physical activity is associated with an attenuation of leukocyte telomere length (LTL) shortening. However, more controversy exists regarding higher exercise loads such as those imposed by elite-sport participation.
The authors investigated LTL differences between young elite athletes (n = 61, 54% men, age [mean ± SD] 27.2 ± 4.9 y) and healthy nonsmoker, physically inactive controls (n = 64, 52% men, 28.9 ± 6.3 y) using analysis of variance (ANOVA).
Elite athletes had, on average, higher LTL than control subjects, 0.89 ± 0.26 vs 0.78 ± 0.31, P = .013 for the group effect, with no significant sex (P = .995) or age effect (P = .114).
The results suggest that young elite athletes have longer telomeres than their inactive peers. Further research might assess the LTL of elite athletes of varying ages compared with both age-matched active and inactive individuals.
Ryan P. Durk, Esperanza Castillo, Leticia Márquez-Magaña, Gregory J. Grosicki, Nicole D. Bolter, C. Matthew Lee and James R. Bagley
follow their normal diet for 7 days and track their dietary intake with MyFitnessPal.com (MyFitnessPal Inc., San Francisco, CA). Participants were given a kit for stool collection at home (DNA Genotek Inc., Ontario, Canada) and were instructed on proper use. Participants’ stool samples and dietary logs