Exercise May Change Sperm in Ways That Benefit Babies Brains

Putting soon-to-be mouse fathers on a six-week exercise regimen before procreating resulted in mice offspring with better brain structure and function than mice born from the sperm of an inactive father, according to a new study. These findings, “Intergenerational Transmission of the Positive Effects of Physical Exercise on Brain and Cognition,” were published April 22 in the journal Proceedings of the National Academy of Sciences (PNAS). The images from this study are breathtaking:

 Patricia Tezano

Staining for neural stem cells expressing SOX2 (red) and GFAP (green) in the subgranular zone of the dentate granule cell layer of an adult male mouse hippocampus. DOI: 10.1073/pnas.1816781116

Source: Patricia Tezano

This pioneering research is part of an effort by various research groups in Spain to better understand the impact that parental lifestyle choices prior to conception may have on offspring.

Last year, another group of researchers from Germany (Benito et al., 2018) reported that physically active male mice passed on cognitive benefits to their offspring via a phenomenon that appeared to be mediated by altered expression of sperm RNA.

For the most recent study on whether fathers who exercise have “smarter” babies, the researchers in Spain started by giving long- and short-term memory tests to a large group of male mice. At this stage of the experiment, they had all of the “sedentary” male mice (none of whom had been given access to a running wheel) impregnate female mice. Then, they put some of these mice on a six-week cardio regimen of wheel running.

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After six weeks, both the exercise and non-exercise control group of male mice were given the opportunity to mate with female mice again. The primary objective was to see if different litters of offspring from the same father before and after he’d participated in a six-week exercise regimen would display any differences in brain structure or cognition .

Notably, the researchers found that mice born to the same father just after completing a six-week exercise regimen did better on memory tests than mice born to him when he was living a sedentary lifestyle. Conversely, progenies born to chronically sedentary fathers in the control group at the beginning and end of the study did not show any changes in their brain structure or function.

The authors explain the importance of these findings in their significance statement:

“We report here the inheritance of moderate exercise-induced paternal traits in offspring’s cognition, neurogenesis, and enhanced mitochondrial activity. These changes were accompanied by specific gene expression changes, including gene sets regulated by microRNAs, as potential mediating mechanisms. We have also demonstrated a direct transmission of the exercise-induced effects through the fathers’ sperm, thus showing that paternal physical activity is a direct factor driving offspring’s brain physiology and cognitive behavior."

The researchers also gave all the male mouse fathers the same memory tests before and after an exercise intervention and found that male mice who had been running regularly on a wheel for six weeks scored higher than their inactive counterparts. A closer look showed that adult male mice who had exercised regularly for six weeks displayed an increased number of neurons in specific regions of the hippocampus. According to the researchers, this is more evidence that aerobic exercise can trigger neurogenesis (birth of new neurons) in adults.

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Of course, because this research was conducted on mice, it would be half-witted and reckless to automatically assume that the exact same results would be replicated in a study on humans. That said, there is a strong possibility that the same changes in gene sets regulated by microRNAs observed in the sperm of male mice who were put on an exercise regimen might also occur in human sperm, too. Therefore, if you are considering having a baby sometime soon: Why not kickstart an exercise regimen today?

Exercise is cost-free. Even if the preliminary results of this research on mice are debunked in the years ahead, you have nothing to lose and will reap countless other health benefits by making exercise a part of your daily routine. If nothing else, the latest findings that regular aerobic exercise may improve the quality of a father's sperm is just one more reason—and an additional source of motivation —to stay active and make healthier lifestyle choices if you're planning on becoming a dad.