Background: Physical activity and alteration of temperature as a source of stress may have adverse effects on male reproduction.

Objectives: The aim of this study was to investigate the effect of chronic swimming and standing in cold, warm and lukewarm water on mouse spermatogenesis.

Materials and Methods: Forty-nine male mice (N = 49) were randomly divided into seven groups: C, control; SwC, swimming in cold water (10°C); StC, standing in cold water (10°C); SwL, swimming in lukewarm water (23°C); StL, standing in lukewarm water (23°C); SwW, swimming in warm water (36°C); StW, standing in warm water (36°C). Animals in swimming groups were submitted to daily forced swimming for five minutes for five consecutive days/week during five weeks. However groups StC, StL and StW were only standing on a raised platform inside the water pool, without swimming, for the same time and duration. Evaluations on day 36 were made using enzyme linked immunosorbent assay (ELISA), Johnsen score and immunohistochemistry for assay of serum testosterone, luteinizing hormone (LH) levels, quality of spermatogenesis and detection of apoptosis, respectively.

Results: Serum LH and testosterone levels as well as Johnsen score were significantly reduced in all groups except for the group standing in lukewarm water (P < 0.05). Apoptosis was increased only in the swimming or standing in warm water groups (P < 0.05).

Conclusions: This study indicates that forced swimming and standing in all water temperatures has adverse effects on male fertility parameters, the only exception is standing in lukewarm water, which seems to be safe for male fertility parameters.