Thursday, July 25, 2013

True or False? Lower Rest Times Equate Lower Total Work Volume for a Given Workout. Plus: The Volume-Increasing Beauty of Progressive Exercise-To-Rest Ratios

Are short rest periods overtly exhausting and will reduce your training volume and compromise the beneficial effects of your workouts?
It sounds completely logical. If you rest less you cannot move as much weight, because you will feel jaded due to the "insuffient" rest (I wonder who defines what "insufficient" is...?). Scientists from the University of Rio de Janeiro have now put this cornerstone of conventional training wisdom to the test and found that things are - once again - not as easy as it would seem.

To this ends, the researchers recruited 16 young trained subjects with at least 1 year of previous training experience and tested the effect 5 different rest protocols would have on the total volume of otherwise identical workouts.

Short vs. long, progressive vs. constant and fixed intervals

Now, instead of telling their subjects to simply rest one minute or three, the researchers had them train the same bench press and triceps extension protocol with 5 sets for each exercise following

  • Suggested read: "Does Rest Matter? Study Finds 7-9%  Increase in Muscle Gains W/ Decreasing Rest Periods." | read more
    exercise to rest ratios (ERR) of 1:3, 1:5, 1:7 and 1:9 (meaning if an exercise lasted 30s, you would rest 90s, 150s, etc.), or
  • progressively increasing exercise to rest ratios (i.e 1:3 after the first, 1:5 after the 2nd, 1:7 after the third and 1:9 after the fourth set), or
  • fixed 2 min rest intervals as you can find them in many of the cookie cutter training prescriptions out there
According to the researchers, these intervals were chosen based on the recommendations by Pincivero et al. (1997) and amount to rest times between 45s and 270s depending on whether trainees perform their exercises at 75% or 90% of the RM (75% ~30s TUT; 90% ~15s TUT).

So what's the optimum, then?

The researchers assessed the number of repetitions per set, the total volume in each set & the whole exercise and calculated the percent variation of the maximum number of reps that were performed within a set. As you can see in figure 1 the differences in terms of maximum reps were not exactly earth shattering - still based on what we see here, you could argue that at least the 1:2 protocol offers a bit too little rest for a compound exercise such as the bench press.
Figure 1: Relative decrease on the transition from one set to another during the 1:3-1:9 exercise:rest ratio intervals, the progressive exercise:rest ratio (IP) and the fixed 2min rest condition (Monteiro. 2013)
On the other hand, the progressively increasing exercise to rest ratios seem to be something that may actually be worth copying. After all, the performance loss on subsequent set appears to be minimal with this workout strategy.
Figure 2: Total volume in reps for the different ERR conditions (Monteiro. 2013)
With an identical total volume (see figure 2) and given the fact that the workout density, i.e. the ratio of training volume to training time, appears to have beneficial effects on the "anabolic hormones", and clear advantages for anyone trying to get rid of some body fat, the IP strategy that did use exercise to rest ratios (ERRs) of 1:3, 1:5, 1:7, 1:9 would probably be a great compromise. That will allow you to handle maximal weights up to the last set and still train with a high volume, while taking advantage of a faster pace on the earlier sets in your workout.

"Ah come on, just another set!" ... "I don't know man, we've already pumped away 100,000kg today... do you really believe that's going to be productive, I mean, yeah, we are cuttin', but still... I mean I don't dig this epic!", "EPOC man, it's called EPOC!" *shakes his head* "Call it whatever you want, bro, I am out!" Interested in the background of this conversation (read more)?
Bottom line: Coming back to the original question from the headline, the most astounding result of the study at hand may in fact be that only the 1:3 exercise:rest ratio produced a statistically significant reduction in total volume. And we do noteven know for sure, whether it would result in suboptimal lean mass and strength gains. Mass gains, in particular, have after all not been found to benefit from rest times beyond 90-120s (Ahtiainen. 2005); and as of now it is unclear whether they would be compromised by rest times ranging from 40-90s, as they were recorded in the 1:3 condition in the study at hand.

So, even if the results of this study tell us only little about the optimal length of the rest period, they do tell us something about an (imho) quite interesting yet rarely applied approach to determine the amount of rest you would need in-between sets, namely by specific ratios of total time under tension to subsequent rest - or, put differently: By resting X seconds for each Y seconds you've just been lifting.

  • Ahtiainen JP, Pakarinen A, Alen M, Kraemer WJ, H√§kkinen K. Short vs. long rest period between the sets in hypertrophic resistance training: influence on muscle strength, size, and hormonal adaptations in trained men. J Strength Cond Res. 2005 Aug;19(3):572-82.
  • Monteiro WD, Venturim FO, Perez AJ, Farinatti PT. Work volume in strength training is not affected by rest interval strategy. J Sports Med Phys Fitness. 2013 Jun;53(3):312-8.
  • Pincivero DM, Lephart SM, Karunakara RG. Effects of rest interval on isokinetic strength and functional performance after short-term high intensity training. Br J Sports Med. 1997 Sep;31(3):229-34.