Longer Rest Periods Compromise Adaptational Response in Resistance Training Older Men in 12 Week Study

Best-agers listen up: If you want to make progress, socialize after your workouts and stick to rest periods in the 60-90s range.

Best-agers, listen up! If you are the kind of person who likes to chat for four minutes between his / her sets you are not just wasting time. You are also making your workouts less effective. While there is little evidence that there are major differences between rest times of 60s and 90s, a recent study from the Division of Biokinesiology and Physical Therapy at the Clinical Exercise Research Center of the University of Southern California is not the first study to suggest that resting longer than maximally 120s is going to compromise the changes in body composition, muscular performance, and functional performance that occur in response to resistance training.

I have to admit, with a mean age of 70.3 years, the 22 male volunteers of said study don't qualify as the "classic" gymrat. On the other hand, you will probably have heard the argument that aging muscle cannot sustain the same extent of high intensity hammering that's highly productive in younger folks against.

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Against that background, it's actually all the more surprising that the 11 men in the 60s rest period groups of this recent 4 weeks resistance training study saw significantly greater increase in lean muscle mass, bench press & leg press 1RM max, performance on the pull-down and several parameters of functional performance (not shown in Figure 1).

Figure 1: Changes in body composition and strength after 8 and 12 weeks; expressed relative to the values that were measured after the 4-week pre-training phase that was identical for both groups (Villanueva. 2014)

Except from the rest times, the periodized strength training regimen was 100% identical for both groups. This means that all 22 study subjects performed the same progressive total body resistance training program which was preluded by a 4-week familiarization protocol that was 100% identical for both groups:

• Training frequency: 3 days/week for the 4-week training cycle
• Sets / reps: 2 to 4 sets with 15 to 8 repetitions (set number increased, rep number decreased over time)
• Exercise number: Four to six exercises per workout

Only after the subjects had completed the first four weeks of training they were paired based on the similarity of their flat bench machine chest press 1-RM and randomly placed into one of the two groups: The SS = short (60s) and the SL = long (240s) rest group. As the scientists say they chose

"this strength outcome measure, because previous work from our lab has indicated there is relatively less variability among study participants with chest press 1-RM val ues, versus leg press 1-RM values, and, therefore, it would allow us to more easily randomize and create two treatment groups that are similar in (upper body maximum) strength.

In the following 8-week 'actual' study period the subjects were subjected to a progressive total-body resistance training program emphasizing development of upper and lower body strength.

• Training frequency: 3 days/week for 8 weeks by both groups (SS and SL)
• Sets / reps: sets ranged from 2 to 3, repetitions from 6 to 4
• Exercise number: 4–6 exercises

During this active study period, the only difference in program design between the two strength RT groups in was the rest interval length utilized between sets: 60 s (SS group) versus 4 min (SL group).

"Throughout the entire resistance training program, all sets were performed maximally for the assigned number of repetitions and with proper lifting technique, and loads were adjusted in accordance with recovery and performance, across the repeated sets progression.

At least in untrained subjects shorter rest periods (60s vs. 150s) may have more beneficial effects on body composition, i.e. they elicit greater lean mass gains and higher losses of body fat (Buresh. 2009)

What about studies in younger subjects? The results are not consistent, but generally speaking there appears to be slight advantage in terms of strength gains with rest periods in the 90s-150s range as they were observed by Robert Buresh et al. (2009) in healthy, recently untrained males. In previously strength-trained men the benefits appear to vanish, when the total exercise volume is not controlled for, though (Willardson. 2008). Moreover, the previously cited study by Buresh et al.  (2009) indicates that shorter rest periods will elicit more favorable changes in body composition (see Figure on the left). We must be careful, though - short is not generally better.  A review by de Salles et al. (2009) indicates that rest periods below 60s can impair the strength gains and while respective data is lacking, it is likely that this will also have negative effects on the amount of lean mass you will gain on otherwise identical training regimen.

Furthermore, it is important to note that study participants were never expected to perform sets to absolute muscular failure; given an appropriate loading progression, with alterations in set/repetition schemes throughout and across microcycles (i.e., a series of 3 training sessions), the repetition maximum assignments allowed for successful completion of the assigned number of repetitions at the load(s) prescribed, across multiple sets, and with minimal need for assistance/'spotting'" (Villanueva. 2014.)

Now this certainly sounds as if the protocol was realistic. But there is one major difference that puts a question mark behind the results of the study: usually regimen with long and short rest times differ significantly in the number of sets and the number of reps. Thus it is possible that future studies using different protocols for both groups would yield different results.

Figure 2: More helps more... at least in elderly study subjects increasing the intake of whey protein after a workout from 20g to 40g will yield significant benefits (Yang. 2012).

Bottom line: The study at hand certainly supports previous evidence that older men and women don't necessarily have to train with the "handbreak firmly fixed". The relatively large increase in strength and functional performance, however, stand in stark contrast to the pathetic increase in lean mass. And the standardized set and rep ranges make it impossible for the 240s rest group to benefit from the ability to train at higher volumes.

Another thing that is wirth mentioning is that the subjects consumed >1.0 gram protein/kilogram body weight/day - without the addition of fast absorbing high BCAA protein sources, however, elderly men (and women) are always having a hard time to build practically relevant amounts of lean muscle.

Against that background, I would love to see this study being repeated with 30-40g of whey protein being consumed in the vicinity of the workout; and in case you want to do your own N=1 experiment using this or any other workout protocol described in the study at hand, I would suggest you make sure to add some extra-protein, as well. Previous studies do after all indicate that "more" as in 40g vs. just 15-20g helps more in men and women in their 60s or older | Comment on Facebook!

References:

• Buresh, Robert, Kris Berg, and Jeffrey French. "The effect of resistive exercise rest interval on hormonal response, strength, and hypertrophy with training." The Journal of Strength & Conditioning Research 23.1 (2009): 62-71.
• de Salles, Belmiro Freitas, et al. "Rest interval between sets in strength training." Sports Medicine 39.9 (2009): 765-777.
• Villanueva, Matthew G., Christianne Joy Lane, and E. Todd Schroeder. "Short rest interval lengths between sets optimally enhance body composition and performance with 8 weeks of strength resistance training in older men." European journal of applied physiology (2014): 1-14.
• Willardson, Jeffrey M., and Lee N. Burkett. "The effect of different rest intervals between sets on volume components and strength gains." The Journal of Strength & Conditioning Research 22.1 (2008): 146-152.
• Yang, Yifan, et al. "Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men." British Journal of Nutrition 108.10 (2012): 1780-1788.