Table 4.
Characteristics of the included studies and relevant outcomes
| Study | Participants | Exercise protocol | Sample | Biomarker | Technique | Findings |
|---|---|---|---|---|---|---|
| Møller et al. [34] | 12 Healthy subjects (7 males and 5 females); MA ± SD = 26.1 ± 4.9 y/o | Maximal bicycle exercise (VO2-max test) under normal conditions and at 4559 m (high-altitude hypoxia) for 3 days | Lymphocytes | SBs,FPG-s s, ENDO III-s s | Comet assay | Increased SBs at hypoxia on all 3 days; ENDO III-s s increased on day 3 at hypoxia; FPG-s s remained unchanged |
| Fogarty et al. [66] | 10 Healthy males; MA ± SD = 23 ± 4 y/o | Treadmill test to exhaustion | Lymphocytes | Tail DNA (%) | Comet assay | DNA damage increased 63% (p < 0.05) after exercise compared to rest |
| Sardas et al. [55] | 12 Male rowers (MA ± SD = 22 ± 3.8 y/o) and 11 PE students (MA ± SD = 21.8 ± 3.8 y/o) | Three-staged exercise test on a rowing (rowers) and bicycle ergometer (PE students) | Lymphocytes | Tail DNA (%) | Comet assay | DNA damage was increased 24 h post exercise compared to pre-exercise in both rowers and PE students but overall pre- and post-exercise damage was significantly higher in rowers compared to PE students |
| Reichhold et al. [47]a | 28 Male triathletes; MA ± SD = 32.7 ± 6.3 y/o | Ironman triathlon (3.8 km swim, 180 km cycle, 42 km run) | Lymphocytes | Tail DNA (%) | Comet assay |
The % of SBs decreased significantly immediately post-race, then increased 1 d post-race and declined again 5 d after the race Between days 5 and 19 post-race the levels of strand breaks decreased further below initial levels |
| Hartmann et al. [70] | 2 Males (20 and 30 y/o) and 1 female (32 y/o) | Treadmill test to exhaustion | White blood cells | DNA migration (μm) | Comet assay | No increase in DNA migration was seen immediately after the test but a significant increase in DNA migration was found after 6, 24 and 48 h. |
| Liu et al. [38] | 8 Males athletes; MA ± SD = 21.35 ± 1.04 | Treadmill exercise to exhaustion | Peripheral blood cells | Tail length; Olive tail moment | Comet assay | Compared to before exercise, both tail length and olive tail moment significantly rose after exercise (p < 0.001) |
| Inoue et al. [56] | 9 Swimmers (MA ± SD = 20.1 ± 1.2 y/o) and 9 distance runners (MA ± SD = 20.9 ± 2.1 y/o) | 1500 m for 90 min (swimmers) and 15 km distance running for 70 min (runners) | Lymphocytes | 8-OHdG | HPLC | 8-OHdG decreased significantly after swimming, but no significant change was observed after running |
| Sacheck et al. [62] | 8 Young (MA ± SD = 25.4 ± 2.2 y/o) and 8 older (MA ± SD = 69.3 ± 3.5 y/o) | Downhill running on a treadmill for 45 min at 75% VO2-max | Leukocytes | 8-OHdG | HPLC | No change in 8-OHdG 24 h post-exercise |
| Revan [61] | 14 Healthy males; MA ± SEM = 22.3 ± 0.5 y/o | Incremental exercise test to exhaustion on a cycle ergometer | Plasma | 8-OHdG | Cayman ELISA Kit | No significant difference in 8-OHdG levels before and after exercise |
| Tanimura et al. [54] | 8 Young untrained (MA ± SD = 23.8 ± 3.2 y/o) and 8 endurance-trained (MA ± SD = 21.1 ± 3.7 y/o) men | Cycling at 75% VO2-max 1 h daily for three consecutive days | Lymphocytes | Tail DNA (%) | Comet assay | DNA damage at day 4 was significantly greater than that at day 1 in both groups |
| Saritaş et al. [63] | 22 Healthy trained men; MA ± SEM = 21.45 ± 0.43 y/o | 12 min run test | Serum | 8-OHdG | ELISA Kit | 8–OHdG levels were not different between the time periods (before exercise, immediately after exercise and 24 h after the exercise) (p > 0.05) |
| Mastaloudis et al. [51] | 5 Males (MA ± SEM = 39 ± 8 y/o) and 5 females (MA ± SEM = 35 ± 4 y/o) | 50 km ultramarathon | Leukocytes | Tail DNA (%) | Comet assay | On average, in both placebo and experimental groups, DNA damage increased at mid-race but returned to baseline values by the end of the race |
| Harms-Ringdahl et al. [50] | 15 Healthy untrained males and females (7 females and 8 males; MA ± SD = 30.5 ± 6.9 y/o | 20 min cycling at 80% of maximum heart rate | Serum | 8-OHdG | ELISA Kit | Levels of 8-OHdG increased 42% after the exercise |
| Hartmann et al. [69] | 3 Male and 3 female athletes (aged between 21-33 y/o) | Short-distance triathlon competition (1.5 km swimming, 40 km cycling, 10 km running) | Lymphocytes | Tail moment (DNA migration) | Comet assay | Increase in DNA migration was seen at 24 h post-exercise, whereas at 48 h the values were lower compared to 24 h but higher than the pre-exercise values. At 72 h, the maximum increase in DNA migration was found and baseline values were still elevated after 120 h |
| Fogarty et al. [67] | 12 Healthy males; MA ± SD = 23 ± 4 y/o) | Bike test at 40,70 and 100% of VO2-max | Leukocytes | Tail length | Comet assay | Increase in DNA damage observed at moderate (70% VO2max) and high-intensity exercise (100% VO2max) compared to rest |
| Tanimura et al. [74] | 15 Healthy sedentary males; MA ± SD = 23.7 ± 1.1 y/o | Cycling at 75% VO2-max for 1 h | Lymphocytes | Tail DNA (%) | Comet assay | There was increased DNA damage at 3 h post-exercise compared to pre-exercise (p < 0.05) |
| Paik et al. [72] | 10 Healthy males; MA ± SD = 25.6 ± 0.8 y/o | Treadmill run to exhaustion at 80% VO2-max | Lymphocytes | Tail DNA (%), tail length, tail moment | Comet assay | There was increased DNA damage measured just prior to the termination of exercise compared to pre-exercise (p < 0.05) |
| Ryu et al. [40] | 30 Male runners, 10 in each group; 10 km group (MA ± SD = 36.5 ± 10.9 y/o), 21 km group (MA ± SD = 45.0 ± 7.8 y/o), 45 km group (MA ± SD = 37.9 ± 13.6 y/o) | 3 different marathon distances: 10 km,21 km and 45 km | Lymphocytes | Tail DNA (%), tail length, tail moment | Comet assay | Compared to rest and recovery, tail moment was significantly higher in all groups. Also, at 45 km tail moment was found to be higher a post-exercise compared to the 10 km and 21 km (p < 0.05). No differences in DNA in tail (%) or tail length was observed |
| Itoh et al. [60] | 8 Untrained males; MA ± SD = 21.8 ± 2.1 y/o | 10 km run | Plasma | 8-OHdG | ELISA kit | Decreased plasma 8-OHdG levels both immediately and 1 h after the 10-km run compared to resting values (p < 0.05) |
| Tsai et al. [75] | 14 Male runners (median age 21, range 20–24 y/o) | 42 km marathon race | Peripheral blood mononuclear cells | Tail DNA (%), FPG-s s, ENDO III-s s | Comet assay | SBs increased on day 1; increased levels of FPG-s s were observed immediately and 24 h (day 1) after the race; ENDO III-s s levels also increased immediately post-exercise and on day 7 |
| Bloomer et al. [59] | 11 & 6 Aerobically trained men and women; MA ± SD = 23.3 ± 5.2 y/o | Treadmill run for 30 min at 80% VO2-max | Plasma | 8-OHdG | ELISA Kit | No significant difference was observed in 8-OHdG levels before and after exercise |
| Turner et al. [76] | 9 Healthy men; MA ± SD = 46.1 ± 5.3 y/o | 233 km ultraendurance race | Peripheral blood mononuclear cells | Tail DNA (%), FPG | Comet assay | Increased SBs immediately and 24 h after the race, compared to baseline (p < 0.01); an increase in FPG-dependent oxidative DNA damage was also observed immediately after the race (p < 0.05) |
| Peters et al. [73] | 8 Male athletes; MA ± SD = 34.2 ± 2.44 y/o | 2.5-h treadmill run at 75% VO2-max | Lymphocytes | Tail length/DNA migration (μm) | Comet assay | There was no significant increase in DNA strand breaks before and after the exercise (p > 0.05) |
| Zhang et al. [78] | 11 Healthy male students aged between 18–20 y/o | Bicycle exercise to exhaustion | White blood cells | Tail length/DNA migration (mm) | Comet assay | Significantly increased DNA migration at 6 h and 24 h compared to pre-exercise (p < 0.01) |
| Wagner et al. [77] | 42 Male athletes; MA ± SD = 35.3 ± 7 y/o | Ironman triathlon (3.8-km swimming, 180 km cycling and 42.2-km running) | Lymphocytes | SBs, Tail DNA (%), ENDO III-s s, FPG-s s | Comet assay | SBs decreased post-race; DNA migration increased 1 day post-race due to SBs (p < 0.01), then 5 days post-race returned to pre-race levels and decreased further to below the initial levels 19 days post-race (p < 0.01) |
| Sato et al. [64] | 15 Male subjects aged 19–29 y/o (7 physically active and 8 sedentary) | 50% VO2-max of cycle ergometer exercise for 30 min | Leukocytes | 8-OHdG | HPLC | No change in physically active subjects but decreased in sedentary subjects |
| Hartmann et al. [68] | 8 Healthy men (29-34 y/o) | Treadmill run to exhaustion | White blood cells | Tail moment | Comet assay | Increase in DNA damage was seen 24 h after the run (mean increase = 35.3 ± 8.3%) |
| Shi et al. [57] | 5 Healthy males (aged 22–38 y/o) | Exercise on a cycle ergometer at 50% VO2-max for 10.5 ± 1.3 min | Leukocytes | 8-OHdG | HPLC | After aerobic exercise, no significant change in leukocyte 8OHdG level was seen. (However, a significant increase was detected in samples taken 24 h after anaerobic exercise) |
| Davison et al. [65] | 7 Healthy males; MA ± SD = 22.3 ± 4.1 y/o | Treadmill test to exhaustion | Peripheral blood mononuclear cells | Tail moment | Comet assay | An increase in DNA damage was observed after exercise |
| Asami et al. [36]a | 23 Healthy males aged 19-50 y/o (10 untrained and 13 trained) | Maximal cycling exercise | Leukocytes | 8-OHdG | HPLC | A significant decrease in 8-OHdG levels was observed in the untrained subjects only (p < 0.05) |
| Briviba et al. [49] | 10 Subjects for half-marathon (5 males and 5 females; MA ± SD = 43 ± 9 y/o) and 12 subjects for marathon (2 males and 10 females; MA ± SD = 45 ± 10 y/o) | Half-marathon (21.1 km) and a marathon (42.195 km) | Lymphocytes | Tail DNA (%), FPG-s s and ENDO III-s s | Comet assay | No significant changes in the levels of DNA strand breaks in lymphocytes after either race. However, a significant difference was found in the % of ENDO III s in the tail after both races (p < 0.05), whereas the % of FPG-s s was slightly increased but not significantly (p > 0.05) |
| Pittaluga et al. [53] | 7 Females; MA ± SD = 68.1 ± 2.7 y/o | Exhaustive bout on a cycle ergometer | Serum | 8-OHdG | HPLC | No significant difference in 8-OHdG levels before and after exercise |
| Niess et al. [39] | 5 UT and 6 TR | Treadmill run test to exhaustion | Leukocytes | Tail moment/DNA migration(μm) | Comet assay | An increase in DNA migration from 2.31 ± 0.20 (TR) and 2.22 ± 0.16 (UT) at rest to 2.65 ± 0.30 (TR) and 3.00 ± 0.41 tail moment (UT) was observed 24 h after exercise |
| Niess et al. [71] | 12 Male runners; MA ± SD = 27.3 ± 4.1 y/o | Half-marathon (21.1 km) | Leukocytes | DNA migration (μm) | Comet assay | DNA migration rose significantly 24 h after the race, compared to rest (p < 0.01) |
| Williamson et al. [80] | 10 Recreationally males; MA ± SD = 22 ± 2 y/o | Treadmill test to exhaustion | Peripheral blood mononuclear cells | Tail DNA (%) | Comet assay | Tail intensity was increased by 18.2% post-exercise (p < 0.05) |
| Orlando et al. [48]a | 21 Rugby male athletes; MA ± SD = 26 ± 5 y/o | 40 min run at 85% of maximum heart rate | Peripheral blood mononuclear cells | Tail DNA (%) | Comet assay | No significances of DNA damage were observed after the exercise bout |
| Meihua et al. [58] | 10 Male athletes; MA ± SD = 21.1 ± 1.13 y/o | VO2-max (Bruce protocol) | Peripheral blood cells and plasma | DNA damage index and 8-OHdG | Comet assay and HPLC | Exercise increased DNA damage index as measured by comet assay; plasma 8-OHdG levels also increased following exhaustive exercise (p < 0.01) |
| Roh et al. [37]a | 10 Male college athletes; MA ± SD = 18.8 ± 0.8 y/o | 1 h run at 75% of heart rate reserve | Lymphocytes | Tail DNA (%) | Comet assay | DNA tail (%) increased following exercise (p < 0.05) |
| Kim et al. [79] | 11 Amateur male triathletes; MA ± SD = 37.9 ± 6.2 y/o | 2 triathlon races (O2 and Olympic courses) | Lymphocytes | Tail DNA (%) | Comet assay | In the Olympic course, DNA tail intensity (%) increased after match and decreased after 3 and 6 days of recovery; In the O2 course, tail (%) decreased after match, increased after 3 days, and decreased after 6 days of recovery (p < 0.01) |
SBs strand breaks, FPG-s s formamidopyrimidine glycosylase-sensitive sites, ENDO III-s s endonuclease III-sensitive sites, 8-OHdG 8-hydroxy-2′–deoxyguanosine, MA mean age, SD standard deviation, HPLC high-performance liquid chromatography, ELISA enzyme-linked immunosorbent assay, PE physical education, VO2-max maximum rate of oxygen consumption; untrained, UT trained, TR, y/o years old
anot included in meta-analyses