Sedentary men who start exercising between three and five times per week improve their sperm counts and other measures of sperm quality in just a few months, according to a new study published today in Reproduction. The researchers also found that men exercising moderately and continuously improved their sperm quality more than those following popular intensive exercise programs like HIIT.
1 in 3 couples struggle to conceive due to poor semen quality. The only treatment available for couples unable to conceive naturally is IVF, but using poor quality sperm may increase the risk of miscarriage, birth defects and the development of childhood cancer.
Current advice for men seeking to improve their chances of conceiving include combining healthy eating with regular exercise while giving up smoking and reducing the intake of alcohol. However, the link between exercise and sperm quality is not definitely proven. Some studies have even shown that strenuous exercise, such as long-distance running and endurance cycling, may actually have a negative impact on sperm quality.
In this study, researchers from the Urmia University in Iran set out to investigate whether the time men spend exercising and the intensity at which they work out have an impact on sperm quality. The researchers investigated 261 healthy men aged between 25 and 40 years old. Men who followed a regular exercise program or did more than 25 minutes of exercise more than 3 days per week were excluded from participating.
The researchers assigned each participant to one of four groups: moderate intensity continuous training (MICT), high intensity continuous training (HICT), high intensity interval training (HIIT), or a control group that did no exercise.
MICT and HICT exercises consisted of running on a treadmill for half an hour and one hour for 3-4 days per week respectively. HIIT consisted of short one-minute bursts of sprinting on a treadmill, followed by a one minute recovery period, repeating between ten to fifteen times. These routines were followed during a 24-week period.
Semen samples were taken before, during and after the different exercise regimens to assess the men's semen volume, sperm count, morphology, motility, levels of inflammatory markers and their response to oxidative stress.
The researchers found that men in all exercise groups had improved sperm quality across all measures when compared to the samples from the control group.
After completing the 24-week program, the MICT exercise group showed the biggest improvements in sperm quality, and also maintained these benefits for longer. Compared to the control group, those following MICT had:
- 8.3% more semen volume
- 12.4% higher sperm motility
- 17.1% improved sperm cell shape/morphology
- 14.1% more concentrated sperm
- and 21.8% more sperm cells on average
However, the benefits to sperm count, shape and concentration started to drop back towards pre-training levels after a week of stopping the exercise program, and sperm motility 30 days afterwards.
"Our results show that doing exercise can be a simple, cheap and effective strategy for improving sperm quality in sedentary men," said Behzad Hajizadeh Maleki, lead author of the study. "However, it's important to acknowledge that the reason some men can't have children isn't just based on their sperm count. Male infertility problems can be complex and changing lifestyles might not solve these cases easily."
The authors noted that while losing weight in general is likely to have contributed to improving sperm quality, MICT may have had the most profound impact on sperm quality because it reduces the gonad's exposure to inflammatory agents and oxidative stress.
The researchers' next steps are to investigate whether the training-induced changes in sperm quality will affect their fertilizing potential.