Fertility and Fitness
The old saying “lead by example” certainly holds true in medicine. That is not to give the impression that I have any delusion of being the fittest guy around, but it certainly helps me know that trying to stay fit is a reasonable goal when I am counseling my patients to do so and I try to hold myself to the same standard. As a physician I have always learned, and thus always counseled patients on, the importance of a healthy diet and exercise: fitness. In an effort to practice what I preach, I go for a 2-3 mile run in the beautiful hill country of Austin overlooking the Capitol of Texas Highway as the sun rises before work. I spend my days providing care for patients in the area of reproductive urology: men’s fertility, sexual, and hormonal health. My days are topped off after seeing patients in clinic or spending the day in the operating room, with a grueling workout with my personal trainer.
We are fortunate to have the Wild Basin Fitness Center directly downstairs in the same building as our fertility center/clinic/IVF lab. That way, I can’t sneak out in the evenings without my trainer catching me. The combination of weights, resistance exercises, and cardiovascular circuits finish off the day in a painfully satisfying manner. I know that staying fit makes me a better doctor.
Days can be very long in medical practice and can be physically taxing. Staying fit allows my body to tolerate long hours at the operative table on a weekly basis and I am a believer in the philosophy that the body fuels the mind, keeping me sharp to provide the best care possible for my patients. This also allows me to push my patients to get fit or stay fit.
Testosterone is believed to be an important factor in a man’s fertility. Low testosterone (total testosterone level of less than 300 ng/dl) appears to be very prevalent in infertile men. Forty-five percent of men with no sperm in the semen without a blockage in the system transporting sperm have low testosterone and 43% of men with low sperm counts have low testosterone levels (1). Sperm are thought to like a testosterone rich environment. Low testosterone can impact a man’s fertility along with causing other issues such as increased fat mass, decreased muscle mass, decreased exercise tolerance and motivation, decreased bone mass, worsened erectile function, decreased sex drive, depressed mood, irritability, tiredness, lack of motivation, sleep disturbances, difficulty with concentration, and hot flashes (2).
So what does this have to do with being fit? Fat cells in the body contain an enzyme called aromatase. Aromatase converts testosterone into estrogen, so the more fat cells there are, the less overall testosterone there is, as it is being converted into estrogen. This makes it tougher to lose fat cells and maintain muscle mass and starts the vicious cycle of turning more testosterone into estrogen and adding more fat. Getting fit can break the cycle and turn things around. By burning fat, more testosterone can be kept as testosterone. It is also believed that men with more body fat have more fat in the scrotum that can increase testicular temperatures and that can be bad for sperm production as well.
Recently it has also been demonstrated that obese men (BMI ≥ 30 kg/m2) have sperm cells with poorer progressive motility (don’t swim as well) as their leaner counterparts. The obese men were also found to have more damaged sperm DNA making these sperm not as good of candidates to fertilize the egg (3).
Obesity is a worsening epidemic in the United States, where currently one third of all American adults are obese (4). An increase rate of male infertility is paralleling the increase in obesity (5). Another recent study looking at previous data from 14 previous studies including nearly 10,000 men has shown that 32.4% of obese men have low sperm counts when compared to 24% in men with normal weight. The percentage of men with no sperm in the semen whatsoever increases from 2.6% up to 6.9% when comparing normal weight men to obese men!
- Sussman EM, Chudnovsky A, Niederberger CS: Hormonal evaluation of the infertile male: has it evolved? Urol Clin North Am 2008; 35(2):147-155
- Kelleher S, Conway AJ, Handelsman DJ: Blood testosterone threshold for androgen deficiency symptoms. J Clin Enocrinol Metab 2004; 89:3813-3817.
- Fariello RM, Pariz JR, Spaine DM, Cedenho AP, Bertolla RP, Fraietta R: Association between obesity and alteration of sperm DNA integrity and mitochondrial activity. Br Jour of Urol 2012; [epub ahead of prin]
- Arterburn DE, Alexander GL, Calvi J, et al.: Body mass index measurements and obesity prevalence in 10 U.S. health plans. Clin Med Res, 8: 126, 2010.
- Swan SH, Elkin EP, Fenster L: Have sperm densities declined? A reanalysis of global trend data. Environ Health Perspect, 105: 1228,1997.