Title, Date of Publication & Journal

Physical activity and television watching in relation to semen quality in young men,

Monday 04 February 2013, British Journal of Sports Medicine

Claim supported by evidence?

The paper suggests that higher moderate-to-vigorous physical activity and lower TV watching may be associated with higher sperm concentration.

Summary

• Well conducted study that collected information on a variety of lifestyle risk factors
• Small sample size

Study Conclusions

The study found higher moderate-to-vigorous physical activity and low TV watching were significantly associated with higher sperm concentrations; weak trends towards higher sperm counts were observed for these factors. No associations between exercise and TV watching on motility or proportion of morphologically abnormal sperm were found.

Study conclusions are based on comparisons between levels of moderate to vigorous physical activity, no trend was observed between levels of mild physical activity and sperm concentration, and in fact sperm concentrations in men that reported mild physical activity were comparable with those that reported vigorous activity.

This was a relatively small study and the possibly that the findings could be due to chance cannot be ruled out. Previous studies have reported inconsistent results.

Strengths/Limitations

Study appeared well conducted and collected detailed information on variety of lifestyle factors which could have had impact on analyses.

Men who were more physically active were shown to have healthier diets than those who watched a lot of TV, however diet was not accounted for in the analyses.

Authors do account for study limitations, such as the inability to conclude whether the observed differences are clinically relevant or whether they translate to differences in reproductive success.

The homogeneity of the study population may limit the generalisability of results.

‘Before the headlines’ is a service provided to the SMC by volunteer statisticians: members of the Royal Statistical Society (RSS), Statisticians in the Pharmaceutical Industry (PSI) and experienced statisticians in academia and research.  A list of contributors, including affiliations, is available here.