Moderate-intensity physical activity is associated with favorable semen-parameter changes and normalization of selected abnormalities in men with impaired semen quality.

backgroundPhysical activity is a potentially modifiable lifestyle factor relevant to male reproductive health, yet evidence among men with confirmed impaired semen quality remains limited. This study examined the association between self-reported physical activity intensity and changes in semen parameters in men with abnormal baseline semen quality.

methodsThis prospective observational cohort study included men undergoing fertility evaluation at a single reproductive center between June 2024 and January 2026. Eligible participants had at least one semen parameter below the WHO sixth-edition reference limits. All participants received standardized lifestyle counseling, but no specific exercise modality, supervised training program, or physical activity group was assigned by the investigators. Physical activity during follow-up was assessed using a study-specific structured questionnaire that recorded self-reported weekly activity duration and intensity using the Borg scale with a practical Talk Test description. Participants were classified at follow-up as inactive, low-activity, or moderate-activity. Associations with 3-month semen parameters were evaluated.

resultsA total of 1,316 men were included: 434 in the inactive group, 430 in the low-activity group, and 452 in the moderate-activity group. Compared with inactivity, moderate-intensity physical activity was associated with favorable adjusted differences in sperm concentration, motility, normal morphology, total progressively motile sperm count, and DNA fragmentation index. The largest relative difference was observed for total progressively motile sperm count, which was 51.01% higher in the moderate-activity group (95%CI, 18.03%-93.64%; P for trend = 0.001). Although no significant association was observed for normalization of low total sperm count or elevated DNA fragmentation index, moderate-intensity physical activity was associated with higher odds of normalization of low sperm concentration (OR, 2.32; 95%CI, 1.12-4.81), low progressive motility (OR, 1.53; 95%CI, 1.09-2.15), low total motility (OR, 2.17; 95%CI, 1.41-3.36), and abnormal morphology (OR, 1.54; 95%CI, 1.13-2.12). The low-activity group showed no consistent favorable associations.

conclusionsAmong men with impaired semen quality undergoing their first fertility evaluation, moderate-intensity physical activity was associated with favorable changes in several semen parameters and with normalization of selected baseline abnormalities. Given the observational design, self-reported exposure, and potential for residual confounding, these findings should be interpreted cautiously and require confirmation in prospective controlled studies.

trial registrationNot applicable. This was a prospective observational cohort study. Although all participants received the same standardized lifestyle counseling, the investigators did not prospectively assign participants to physical activity levels, exercise regimens, or comparison groups. Physical activity exposure was self-selected during follow-up and classified analytically at the 3-month visit. Therefore, the study did not meet the WHO/ICMJE definition of a clinical trial requiring prospective assignment to a health-related intervention to evaluate health outcomes.