Hormonal Responses to Resistance Exercise Variables
Posted Jan 26 2009 4:27pm
Marx et al (2001) examined the long-term training (6-month training regime) adaptations assocated with a low-volume (circuit) resistance training program versus a periodized, high volume resistance program in college-aged women. The study found that subjects who followed the periodized, high-volume resistance program had higher levels of testosterone and insulin-like growth factor-1 (a muscle building hormone) and lower levels of cortisol after 24 weeks of training compared with subjects who followed the circuit program. Greater increases in muscular strength, power and speed were also seen in the high-volume group.
In the muscular strength protocol, the number of sets did not affect the hormonal profile. In the muscular hypertrophy and strength endurance protocols, there was an increase in cortisol and growth hormone levels when 4 sets were performed versus 2.
Training Volume. Acute and chronic research shows that higher-volume resistance programs tend to elicit the greatest hormonal responses.
Rest Period. Trainers are always working to create the most time-efficient workouts for their busy clients. Previous research (Kraemer et al. 1990) suggested that a shorter rest period (1 minute versus 3 minutes) elicited slightly higher acute hormonal responses. However, a newer study (Ahtiainen et al. 2005) suggests that changes in strength, mass and hormone elevations do not differ significantly, whether the rest period is 2 minutes or 5 minutes.
Training to Failure Versus Not to Failure
The results showed that 11 weeks of training to failure or not to failure resulted in similar gains. However, after the identical 5 week peaking period, the not-to-failure group showed greater increases in strength, power and resting testosterone levels and greater reductions in cortisol levels compared with the failure group. The failure group did show a greater increase in muscular endurance measured by bench press repetitions and a decrease in insulin-like growth factor 1.
Resistance exercise protocols that stress large muscle mass (i.e., that use multi-joint exercises) and are high in volume and moderate to high in intensity tend to produce the greatest hormonal elevations, thus resulting in optimal muscular fitness benefits (Kraemer et al. 2005).