Said study was conducted by Crewther et al. and published recently in the Biology of Sport. It examined the effects of two equal-volume resistance-training protocols upon strength, body composition and salivary hormones in male rugby union players.
The scientists used a crossover design, involving 24 male rugby players (mean age 29.8 ± 6.8 years; height 179.5 ± 7.9 cm; body mass 92.9 ± 12.2 kg) with at least 2 years of resistance-training experience (3-4 times per week) who completed a 4-week full-body (FB) and split-body (SB) training protocol of equal volume during the competitive season.
"Both training approaches involved 3 weekly sessions (Monday, Wednesday and Friday) completed between 1600 to 1800 hours. Training involved 8 repetition maximum lifts for selected exercises, performed for 3-6 sets with rest periods of 60-90 seconds between sets and exercises. In the FB protocol, all muscle groups were ex ercised during each of the 3 weekly training sessions, while in the SB protocol only a sub-set of the muscle groups was exercised dur ing each session. The prescribed exercises included; back squats, leg curls, leg press, bench press, bent-over row, pull downs, shoulder press, bicep curls and calf raises. To equate for training volume, the total number of repetitions prescribed each week were identical (i.e. FB training = 21 exercises, 2-3 sets × 8 repetitions; SB training = 13 exercises, 3-6 sets × 8 repetitions). The 2 protocols are commonly used in research and practice and these were incorporated into the weekly schedule of the study population to improve the ecological validity of our findings. A standard warm-up was performed before all training sessions comprising of basic exercises performed with increasing intensities and stretching of the major muscle groups , with the athletes self-selecting the inten sity and duration of stretching" (Crewther. 2016).One repetition maximum (1RM) strength, body composition via skinfold measurements and salivary testosterone (T) and cortisol (C) concentrations were assessed pre and post training.
|Figure 1: Rel. changes in strength (1RM in bench presses and squats) and body composition (body mass, body fat (%), fat mass and fat free mass) during the FB and SB training phases (Crewther. 2016).|
|Figure 2: Post training period (not immediately post-workout) changes in hormone concentration (Crewther. 2016).|
"slope testing on the individual responses identified positive associations (p ≤ 0.05) between T and C concentrations and absolute 1RM strength in stronger (squat 1RM = 150.5 kg), but not weaker (squat 1RM = 117.4 kg), men" (Crewther. 2016),a result that does not exactly make it easier to decide whether the hormonal differences were corollary or causative for the differential effect on the body composition of the athletes. What is quite clear, though, is that even within a short window of training, both, FB and SB protocols, can improve strength and body composition in rugby players.
In that, the scientists rightly point out that "[t]he similar strength gains highlight training volume as a key adaptive stimulus" - a result we've encountered in numerous previous studies, as well. What is "news", though is that the program structure (i.e. FB or SB) had a measurable influence on the the body composition and hormonal outcomes, of which the latter were only partly (namely in the strong athletes) related to the strength gains.
- Crewther BT, Heke TOL, Keogh JWL. The effects of two equal-volume training protocols upon strength, body composition and salivary hormones in male rugby union players. Biol Sport. 2016;33(2):111–116.