Strength Training Principles

Hormonal Impact of Strength Training

Resistance training has been shown to elicit a significant alteration in hormone levels. The hormones that most weight lifters are interested in increasing include testosterone & growth hormone. Both of these hormones are ‘anabolic’, meaning they facilitate growth. According to Kraemer & Ratamess (2005) protocols that are high in volume, moderate to high in intensity, using short rest periods and targeting large muscle groups tend to produce the greatest increase in hormone levels such as testosterone and growth hormone. Weight training also causes an increase in cortisol (stress hormone), as well as adrenaline & neurodrenaline from the adrenal gland. For this reason, it is best not to perform resistance training late at night or where there is a tendency towards difficulty sleeping.

Weight training to failure versus non-failure

Izguierdo et al. (2006) researched the impact of a group performing resistance training to failure & compared this with a group performing resistance exercise to non-failure.  The results demonstrated that both groups demonstrated similar increases in strength & muscle power after 11 weeks of training.

Rest Period Between Sets

Ahtiainen et al. (2005) compared the impact of a two minute rest period versus a longer 5 minute rest period during a 6 months strength training programme with 13 recreationally trained men. No difference in strength, muscle mass or hormone profile (testosterone, growth hormone or cortisol) were found.


Ahtiainen et al. (2005). Short vs. long rest period between the sets in hypertrophic resistance training: influence on muscle strength, size, and hormonal adaptations in trained men. Journal of Strength & Conditioning Research, 19(3); 572-582


Izguierdo et al. (2006)


Kraemer & Ratamess (2005). Hormonal responses and adaptations to resistance exercise & training. Sports Med; 35(4): 339-361.