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  • Luke French, Health Coach

Exercise, Sex Hormones and Health



It is increasingly common to see people signing up for marathons, triathlons and IronMans, long distance cycle events and much more. These people may think it is beneficial for their health, by increasing exercise and acuity, but this is a little bit dramatic. I would say a Saturday morning park run is healthy, not continuously exercising for 10-15 hours in on day (IRONMAN) along with all the training and mileage you have to clock up to train for it.

Sex hormones plummet massively due to stress and this is studies massively in endurance athletes who complete long distance events like the previously mentioned. Testosterone is at all time lows, menstrual cycles are ruined and the body undergoes serious physiological adaptations in order to compensate for the stress load dropped on it.


For example. Males who do extreme amounts of exercise, such as football players, distance runners and cyclists, covering 40-50 miles per week or more, have less reproductive/sex hormones in the bloodstream, consequently meaning far smaller levels of testosterone in the system, smaller testes and less functional sperm. They also have higher levels of glucocorticoids in the bloodstream, which could lead to a whole host of detrimental metabolic and cardiovascular effects such as high blood pressure, obesity, diabetes, strokes, heart attacks, metabolic syndrome and so on (that’s a topic for a different blog). So if you do lots of endurance events/training, i would ask yourself about your libido, testosterone levels, growth hormones levels, and consequently the functioning of your reproductive system. This is not just to make babies, but the sex hormones are essential for baseline health and gender characteristics.


This is not just seen in males, in females it is just as evident. Up to half competitive runners have menstrual irregularities, and highly athletic girls reach puberty later than usual. 1 study of 14 year old girls approximately 95% of the control group had started menstruating, whereas 30% of runners and gymnasts had not. Proving the disruption endurance, chronic and excessive cardiovascular work has on the reproductive hormones. Do you really want to sacrifice all of this just to get the ‘much needed’ mileage in, in preparation for the race.

Obviously too much chronic, excessive exercise causes various harmful physiological adaptations. 30 year-old athletes who run 40-50 miles a week can wind up with decalcified bones, as the stress response elicits greater resorption of skeletal mass, obviously leading to osteoporosis, with increased risk of stress fractures and scoliosis. (and that’s just for a 30 y/o athlete. How old are you?)


Where people go wrong is frequencies and intensities. Everyone knows strength training has THE MOST benefits in all modalities of sport. If a runner had to chose either the weight room or the track, the weight room would bring the most bang for your buck in all forms of beneficial adaptation for race day (yes - including improved aerobic capacity).

So, if after every run, cycle, swim, or whatever form of training you do for an endurance event, you are red faced and sweaty, coming home tired and fatigued because you ‘smashed’ your session, you are probably doing more harm than good.

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