The effect of short‐term strength training on human skeletal muscle: the importance of physiologically elevated hormone levels

Abstract

The effect of strength training and endogenously elevated hormone levels (plasma testosterone, growth hormone (GH) and cortisol) was studied in 16 young untrained males, divided into an arm only training group, A, and a leg plus arm training group, LA, in order to increase circulating levels of anabolic hormones. Both groups performed the same one-sided arm training for 9 weeks, twice a week. Group A trained only one arm (AT), the contralateral arm serving as control (AC), whereas group LA additionally trained their legs following the training of the one arm (LAT), with the contralateral arm serving as control (LAC). In spite of the attempt to match the two groups, the initial isometric arm strength was 20-25% lower for group LA compared to group A (significant for the arm to be trained). Isometric strength increased significantly in LAT and LAC by 37% and 10%, respectively, while the 9% and 2% increases in AT and AC, respectively, remained insignificant. Isokinetic strength increased at one out of three velocities tested for the trained arm relative to the untrained arm in both group A and group LA (P<0.05). Functional strength increased significantly by 20% in LAT, 18% in LAC, 19% in AT, and 17% in AC. Hormonal responses were monitored during the first and last training sessions. Resting hormone levels remained unchanged for both groups. However, during the first training session plasma testosterone as well as plasma cortisol increased significantly in group LA but not in group A. Plasma GH rose in all exercise tests, except during the last test in group LA, but was significantly higher in group LA than in group A in the first training session. In conclusion, a larger relative increase in isometric strength was found in the group having the highest hormonal response. However, due to the initial difference in isometric strength caution must be taken with the interpretation of this finding, which may only indicate a possible link between anabolic hormones and muscle strength with training.

Physiological elevation of endogenous hormones results in superior strength training adaptation

“…The ~21% increase in 1RM biceps curl in L+A is in line with other studies using similar strength training intervention, while the ~14% increase in A is slightly below the expected improvement (McCall et al 1996;Moss et al 1997;Hansen et al 2001;McBride et al 2003). The observations of superior gains in 1RM biceps curl and CSA in the L+A arm indicates that the acute elevations in circulating hormones contributes to strength training adaptations.…”

“…However, in the study by Hansen et al (2001) legs were also trained after arm exercises and a somewhat additive effect on isometric strength, but not on isokinetic and isotonic strength was reported. Another difference from the study by Walker et al is that in the present study, one arm was subjected to L+A training, while the other arm was subjected to the A training.…”

“…However, there is no consensus regarding the longterm effects of the transient exercise induced increase in anabolic hormones on strength training adaptations. It has, however, been observed that acute increases in circulating factors have an additive effect on strength training adaptations (Hansen et al 2001;Madarame et al 2008) and that acute elevation in endogenous testosterone (by strength training) potentiates the androgen receptor response to a strength training session (Spiering et al 2009). On the other hand, it has been observed increased CSA and strength after strength training without any acute elevations in circulatory hormones (Wilkinson et al 2006) and that exposure of loaded muscle to exercise-induced elevations in endogenous anabolic hormones do not enhance strength training adaptations (West et al 2010).…”

Effect of Conjugated Linoleic Acid on Testosterone Levels In Vitro and In Vivo After an Acute Bout of Resistance Exercise

“…The results of this study will help practitioners and coaches to understand if the CLA supplementation can be useful to increase the testosterone synthesis immediately after an acute session of resistance exercise affecting the anabolic phase followed by each strength training session. It has previously been suggested that the acute elevation of testosterone could mediate an anabolic phase after each strength training session, when the muscle is exposed to the anabolic hormone only for a short period (13). Conjugated linoleic acid induced an increase in testosterone production in our in vitro experiments.…”

The effect of L-ornithine hydrochloride ingestion on human growth hormone secretion after strength training

“…In addition, all sets required 10 repetitions and a 90 second rest was set between trials. The range of elbow joint motions for the concentric part was fully extended from 145 to 155°, flexed and means velocities for one repetition including concentric and eccentric motions were in a range of 100-150°/s [13]. The second blood drawing was conducted 30 minutes after the strength training.…”