"Testosterone: No Strength Gains without It!"

by: Robbie Durand, M.A.

Samson was a legendary warrior and is something of a Herculean figure, using massive strength to combat his enemies and perform heroic feats unachievable by ordinary men: wrestling a lion, slaying an entire army with nothing more than a donkey's jawbone, and tearing down an entire building. Samson would have definitely been a hardcore reader of Fitness Rx for Men with feats of strength like that.  Eventually Samson tells his wife Delilah that he will lose his strength at the loss of his hair. Delilah calls for a servant to shave Samson's head as he sleeps.  Sampson wakes up an ordinary man having lost all his superhuman strength.  It may not have been the loss of his Samson's hair that caused his strength loss...maybe it was his testosterone levels!  The research on testosterone and strength training is complex and is not as clear cut as one would expect.  For example, examinations of elite Olympic weightlifters have shown no changes in testosterone over a 1-year training period5.  Others have shown that during a 2 week heavy weight training session there was a 12% reduction in resting testosterone concentration6.  There is a fine line between training hard enough to present an overloading stimulus and prompt new muscle growth and training too hard where the body cannot adapt quickly and efficiently enough before the next training session. When one pushes the body past its limits this is termed "overreaching". Men involved in heavy resistance exercise "overreaching" programs results in reductions in testosterone during strength training as well32.    Furthermore, women can have large increases in strength from a resistance exercise strength training protocol yet have low endogenous testosterone levels4.  Just how important is testosterone for increasing muscle strength?  In this month's American Journal of Physiology Endocrinology and Metabolism, a research study documented that without testosterone, you can expect zero strength gains from a heavy resistance training protocol.  Testosterone is just like Sampson's magic hair...you need it to be strong, but just like Sampson cutting his hair, loss of testosterone will impede strength gains.  In the study, 22 young men with minor experience with strength training participated in this double-blinded intervention study. It was important to use relatively untrained subjects because when untrained subjects start a strict weight lifting program they make huge gains in strength.  The subjects were randomized to treatment with a medication called goserelin which is a gonadotropin-releasing hormone agonist (Goserelin acts on the pituitary gland in the brain and affects leutinizing hormone (LH) release which stimulates testosterone release. With chronic administration of goserelin, it desensitizes the pituitary gland. This means that the pituitary gland produces less LH, which in turn stops the production of testosterone.) or a placebo subcutaneously every 4 weeks for a period of 12 weeks. The strength training period of 8 weeks included exercises for all major muscles (3-4 sets per exercise x 6-10 repetitions) and 1 minute rest periods between sets.  The protocol was designed to cause acute increases in testosterone which has been validated by previous investigations2.  The subjects that received the goserelin had a decrease in testosterone that was 10% lower than that of normal males whereas testosterone remained constant in the placebo group. So here is where the importance of testosterone becomes clear for muscle strength and weight loss.  The goserelin group showed no changes in isometric knee extension strength after training, whereas the placebo group had increased strength gains. Body fat mass increased by 3lbs. in the goserelin group while it decreased by 1.3 lbs in placebo group. Interestingly, even though the goserelin group had below normal testosterone they still were able to gain small increases in lean mass, but not as much as the placebo group.  The study demonstrates that testosterone is one of many growth factors controlling muscle growth (i.e., GH, IGF-1, intramuscular growth factors). The researchers concluded that endogenous testosterone is of paramount importance to the adaptation to strength training. So how can subject’s not having changes in resting testosterone but have increases in strength and lean mass?  Researchers in the study suggested that the acute increases in testosterone produced during the high intensity weight training program may have been a key regulator of those subjects gaining strength and size.  The research findings are in agreement with other researchers who have shown acute elevations in circulating anabolic hormones are potent stimulators of strength.  For example, Hakkinen et al.3 reported that when subjects were divided into arm only training group and arm plus leg training group, the arm and leg group had greater increases in testosterone and growth hormones than arm training alone that resulted in greater increases in isometric arm strength compared to arm training alone.  It's interesting that the even though both groups trained arms that the group that trained both arms and legs had greater increases in arm strength.  Additionally, the larger gains in strength from arm and leg training were related to the larger increases in GH and testosterone produced during the exercise sessions.