|Image 1: If you want to build Arnold-esque arms you better not sit around too long in-between your sets.|
For their study, the results of which are going to be published in the next issue of the Journal of the International Society of Sports Nutrition, Tacito P. Souza-Junior and his colleagues recruited 22 "recreationally trained" men with a minimum of one year resistance training experience at a frequency of 4 sessions a week, who were randomly assigned to one out of two exercise protocols, which differed only in the time the subjects were allowed to rest in-between sets (cf. figure 1).
|Figure 1: Identical training protocol for all subjects participating in the study (compiled based on information from Souza-Junior. 2011)|
|Figure 2: The rest times decreased according to a standardized protocol by 15 sec each week.|
|Figure 3: 1RM performance (in kg) for bench press and barbell squat before and after the 8-week training period in subjects with constant and decreasing rest periods (data adapted from Souza-Junior. 2011).|
|Figure 4: Muscle CSA (in cm²) of arm and tigh muscles before and after the 8-week training period (data adapted from Souza-Junior. 2011).|
There is a spark of truth to every myth
To give you an idea of how significant - and I am talking about "posing significance" not statistical significance here - this is, I have calculated the respective increases in arm- and tigh-circumference, which would differ by 0.4cm and 0.7cm, respectively. Not really outstanding, but nevertheless an important finding of which the researchers say that it lends support to the notion that
decreasing [rest] interval[s] seems to be more efficient than constant interval to produces [sic!] hypertrophic responses.It has yet to be stated that the 11 subjects in the decreasing rest interval group paid dearly for this increase in muscular hypertrophy, as their "exercise performance" as measured by the total workload per session decreased profoundly from week 1 to week 8: -35% total volume for barbell squats and -30% for bench presses. The subjects who used constant rest periods, on the other hand, increased their total volume by +20% for squats and by +30% for bench presses. That being said, all powerlifters out there better stick to their constantly (long) rest periods if they do not want to compromise their game.