Long-Term Effects of (Natural) Bodybuilding on Testosterone Levels

Is bodybuilding good for your testosterone?

In bodybuilding, we are told that our workouts should not last more than 45 minutes! Why? Because past this 45 minute limit, our testosterone production is supposed to fall. No one seems to criticize this statement which is, in fact, a very stupid one.

I have weight-trained for 25 years without any major injury. One of the reason for this is that I warm up extensively. In winter, it is not rare that I need 45 minutes to get fully warmed up prior to my first heavy set. What should I do? Stop right after my warm up because I am already beyond the 45 minute limit?

We also know that a post-training supplementation high in both proteins and carbohydrates negatively influences our testosterone levels. Yet, everybody recommends it despite this inhibitory effect. So, we limit your workout volume to preserve our testosterone. Yet, we gladly impair its output right after the workout with a high protein / high carb feeding? Go figure!

Hypogonadism and natural bodybuilding

If bodybuilding is such a good testosterone booster, why do so many seasoned lifters suffer from a very low testosterone level? And I am not talking about former steroid users only. Are they all overtrained? The answer is no. The fact is, long term bodybuilding may not be that good for your endogenous testosterone production.

If you look at the scientific research measuring testosterone output after an intense workout, you will find that some studies show an increase. Others fail to demonstrate any effect on testosterone output. Also, some studies report a reduction in testosterone. So, the testosterone response to a workout is very hard to predict. But I can clearly see a trend: the more advanced you are, the less likely your are to respond positively.

Lactate as a powerful endocrine stimulator

There is a very interesting study that sums up those various trends. Sprinters ran 400 meters as fast as possible. The run lasted around 45 to 50 seconds. This is very interesting because this is how long a normal bodybuilding set lasts. Among these sprinters, some were of Olympic caliber with around 8 years of training. Others were not so advanced with only 4 years of practice under their belt. The elite sprinters produced the most effort in the least amount of time (45 s). Their blood lactic acid concentration increased 1100%. The less advanced sprinters cover the 400 m in 48 s. As their efforts were less intense, their blood lactic acid level increased only 800%. Because of those strong lactic acid elevations, one would expect testosterone level to increase. During an intense effort, the lactate from the lactic acid is supposed to be a very powerful endocrine stimulator.

As a result of this intense run, the luteneizing hormone (LH) level (the hormone triggering the testosterone release):

• almost doubled (+ 100%) in ALL the elite sprinters;
• in the less advanced runners, LH concentration raised only 25%. It increased in most runners of this group but decreased in a minority of them.

Normally, a LH elevation is associated with an increase in testosterone production. This is what we see in the less advanced runners with a 27% increase in total testosterone and a 60% increase in free testosterone. No matter how their LH responded, ALL of them experienced an elevation in blood testosterone.

45 seconds are enough to reduce your testosterone concentration!

The testosterone response in the elite athletes is far more interesting. Despite the very robust LH elevation, ALL of them experienced a decrease in testosterone output. Total and free testosterone decreased 11% and 26%, respectively. So much for the 45 min limit beyond which testosterone might start to decrease. We see in this study that in advanced athletes, an all out effort of 45 seconds is enough to decrease testosterone. This acute effort produced a long lasting negative effect. It took the sprinters 24 h to have their testosterone level back to normal.

Would steroid usage explain this strange phenomenon? I do not think so as their baseline testosterone, LH and follicle-stimulating hormone (FSH) [another testosterone stimulating hormone] levels were normal before the 400 meter run.

Testicular Exhaustion – Explanation for this Unexpected Response?

The answer to the paradox of having a strong LH elevation and negative testosterone response is simple. The testes of these advanced athletes are “exhausted”. Their constant stimulation ends up having a very negative impact on their capacity to manufacture androgens.

In this study, this exhaustion occurred after only 8 years of training. Basal testosterone is not affected, yet. Subjects were still pretty young (25 year old), too. With more training years and as you get older, basal testosterone production is likely to suffer, too. I think this exhaustion explains why so many advanced (natural) bodybuilders end up having low levels of androgens or end up producing no testosterone at all.

An accelerated form of aging?

Note that the free (bio-available) testosterone is the most affected in both groups. It increased the most in the least experienced athletes compared to total testosterone. It decreased the most in the elite group. In that, it resembles to an accelerated form of aging. As we age, the production of the proteins that bind testosterone increases 1% every year. If our testosterone output decline yearly, our free portion is the most negatively affected.

What are the consequences bodybuilding training and testicular exhaustion?

The ‘testicular exhaustion’ is a factor one should take into account when planning his bodybuilding career. When you thing about it, the future does not look very bright. Up to the age of 25, I could tell that a workout, especially a leg workout, was increasing my testosterone level. More than 10 years later, such a feelable kick is very, very rare.

1. Unless you want to become a pro bodybuilders, I would not recommend starting using steroids before reaching this exhaustion stage.
2. Low calorie diets are obviously not a good thing for your testosterone output. This is why I am against the bulking up phase, especially for natural bodybuilders. Overfeeding is not a very strong stimulator for your testosterone production. On the other hand, underfeeding is a potent inhibitor of testosterone output. After several years of bulking up, a severe diet might precipitate this testes exhaustion.

The new logic of the aging bodybuilder

Statistical studies suggest that muscles can still grow despite a low testosterone output. In fact, muscles growth is more closely related to testosterone receptor density than testosterone level. This indirect finding suggests that testosterone receptors can self activate in the absence of testosterone if muscular contractions are intense enough. But in extreme case of exhaustion, testosterone replacement therapy (TRT) might be the only solution.

Reference

Slowinska-Lisowska M, Majda J. Hormone plasma levels from pituitary-gonadal axis in performance athletes after the 400 m run. J Sports Med Phys Fitness. 2002 Jun;42(2):243-9.