Exercise and its effect on sperm quality is investigated in a new study.
An estimated 1 in 3 couples find conceiving difficult because of poor semen quality.
Often, these couples only have in vitro fertilization (IVF) as a treatment option; however, poor sperm quality is known to increase the risk of miscarriage, birth defects, and childhood cancer.
Because of this, ways to naturally increase sperm quality are important for the health and well-being of current and future generations.
Advice given to men to improve sperm quality includes eating well, reducing alcohol intake, quitting smoking, and exercising regularly.
Although this is the standard mantra, evidence for the impact of exercise on sperm quality has, to date, been contradictory.
Some studies have shown that intense exercising - such as endurance cycling and long-distance running - can reduce sperm quality.
Conversely, other studies have found that certain types and durations of exercise have a positive impact on sperm quality.
Exercise interventions and sperm quality
A team of scientists, from Uremia University in Iran, set out to investigate the effects of exercise intensity on a range of sperm parameters.
In total, 261 healthy men, aged 25-40, were included in the study. At baseline, none of the men followed a regular exercise plan or did more than 25 minutes of exercise more than 3 days each week.
The men were split into four experimental groups:
- Moderate-intensity continuous training (MICT) - running on a treadmill for 25-30 minutes, 3-4 days per week
- High-intensity continuous training (HICT) - running on a treadmill for 50 minutes-1 hour, 3-4 days per week
- High-intensity interval training (HIIT) - 1-minute bursts of treadmill sprinting followed by 1 minute of recovery, repeated 10-15 times
- Control group - no exercise.
Each routine was followed for 24 weeks. Semen samples were evaluated before, during, and after the exercise period to assess sperm count, motility (the ability of the sperm to move), morphology (size and shape), levels of inflammatory markers, and their response to oxidative stress.
The role of oxidative stress - specifically reactive oxygen species - is a growing area of focus in fertility research. Although reactive oxygen species are vital in the fertilization process under normal conditions, if they are not under tight physiological control, they can negatively impact the overall quality of sperm.
Changes in semen following exercise
All exercise groups, when compared with the controls, had improved sperm quality across all measures. The best performing of the three experimental groups was the MICT exercise group; compared with the controls, MICT had:
- 8.3 percent more semen volume
- 12.4 percent higher sperm motility
- 17.1 percent improved sperm cell shape/morphology
- 14.1 percent more concentrated sperm
- 21.8 percent more sperm cells.
These results are impressive, but the changes were not long term. Measures of sperm count, shape, and concentration dipped back toward pre-training levels 1 week after the exercise regimen had ended; sperm motility dropped back after 30 days.
"Our results show that doing exercise can be a simple, cheap, and effective strategy for improving sperm quality in sedentary men. 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."
Lead author Behzad Hajizadeh Maleki
The authors note that a loss of weight during the exercise plan might well have been an important factor in the improvement of sperm quality. They also believe that MICT had a particularly positive effect by reducing the teste's exposure to inflammatory agents and oxidative stress.
The next step for the Iranian team will be to see if these measurable changes in sperm quality will translate into an increased ability to fertilize. As further research is conducted to back up these findings, in the future, sperm-specific training packages could hopefully be designed, raising the chances of fertilization without medical intervention.