Submitted on November 4, 2005
Accepted on January 8, 2006
DIFFERENTIAL EFFECTS OF STRENGTH TRAINING LEADING TO FAILURE VERSUS NOT TO FAILURE ON HORMONAL RESPONSES, STRENGTH AND MUSCLE POWER GAINS
Mikel Izquierdo1*, Javier Ibanez1, Juan Jose Gonzalez-Badillo2, Keijo Hakkinen3, Nicholas A. Ratamess4, William J. Kraemer5, Duncan N. French6, Jesus Eslava1, Aritz Altadill1, Xabier Asiain1, and Esteban M. Gorostiaga1
1 Studies, Research and Sport Medicine Center, Government of Navarra, Pamplona, Navarra, Spain
2 Olympic Center of Sport Studies, Spanish Olympic Committee, Madrid, Madrid, Spain
3 Department of Biology Physical Activity, University of Jyvaskyla, Jyvaskyla, Jyvaskyla, Finland
4 Department of Health and Exercise Science, The College of New Jersey, Ewing, New Jersey, USA
5 Department of Kinesiology, Human Performance Laboratory, University of Connecticut, Storrs, Connecticut, USA
6 Institute of Sport, Northumbria University, Northumbria, United Kingdom
* To whom correspondence should be addressed. E-mail: mikel.izquierdo{at}ceimd.org.
The purpose of this study was to examine the efficacy of 11 weeks of resistance training to failure vs. non-failure, followed by an identical 5- week peaking period of maximal strength and power training for both groups as well as to examine the underlying physiological changes in basal circulating anabolic/catabolic hormones. Forty-two physically-active men were matched and then randomly assigned to either a training to failure (RF; n=14), non-failure (NRF; n=15) or control groups (C;n=13). Muscular and power testing and blood draws to determine basal hormonal concentrations were conducted before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3). Both RF and NRF resulted in similar gains in 1RM bench press (23% and 23%) and parallel squat (22% and 23%), muscle power output of the arm (27% and 28%) and leg extensor muscles (26% and 29%) and maximal number of repetitions performed during parallel squat (66% and 69%). RF group experienced larger gains in the maximal number of repetitions performed during the bench press The peaking phase (T2 to T3) followed after NRF resulted in larger gains in muscle power output of the lower extremities, whereas after RF resulted in larger gains in the maximal number of repetitions performed during the bench press. Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration. This investigation demonstrated a potential beneficial stimulus of NRF for improving strength and power, especially during the subsequent peaking training period, whereas performing sets to failure resulted in greater gains in local muscular endurance. Elevation in IGFBP-3 following resistance training may have been compensatory to accommodate the reduction in IGF-1 in order to preserve IGF availability.
