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Muscle Building: Optimum Rest Interval Between Sets

The optimum length of recovery [between sets] for muscle hypertrophy/muscle building is still a widely disputed area amongst the bodybuilding community. Some bodybuilders prefer longer recovery periods in order to maximize the weight lifted in each set, whilst others prefer shorter rest periods which increases the average intensity of the workout (since less time is spent resting) and allows a greater amount of work to be performed in a set time period. 

Currently most experienced bodybuilders tend to utilise a short between-set recovery period - typically lasting 30-60 seconds. This is supported by research which suggests that keeping rest periods short (around 30-60seconds between sets) enhances the increase in growth hormone response to exercise and may be beneficial for muscle hypertrophy (Willardson 2006; Bottaro et al., 2009; Rahimi et al 2010). 

Rest Interval Between Sets and Hormonal Responses

Research looking at the Growth Hormone responses to varying rest intervals (30, 60 or 120 seconds) in previously strength trained women found that the greatest GH response occurred with rest intervals of 30s (Bottaro et al., 2009). A further study looking at hormonal responses (growth hormone and testosterone) to three different rest intervals (60, 90 or 120s) during 4 sets of 85% 1RM (Rahimi et al 2010) in experienced resistance trained men, found that the 60s rest interval led to the greatest increases in GH whilst the 120s rest interval resulted in the greatest testosterone response.

A recent study (Villanueva et al., 2012) looking at the acute increases in total testosterone following 3x10reps (70% 1RM) to 60 and 90s recoveries found that short rest intervals increased the total testosterone response to resistance training. The researchers suggest that shortening rest intervals may enhance muscle strength and size over longer training period. Taken together the results indicate that shorter rest intervals (30-60secs) appear to enhance the growth hormone response and appear to be more beneficial for muscle hypertrophy.

Rest Interval Between Sets and Muscle Hypertrophy

Research (de Souza-Jr et al., 2010) comparing the effects of a decreasing rest intervals (2mins decreasing to 30 seconds over a 6-week period) with a constant interval rest interval (2mins recovery maintained throughout the 6-week period) found that both were equally as effective for increasing maximal strength and cross-sectional area. Whilst this may not seem significant, it is important to consider that the shorter rest interval (30 seconds) allows for a significantly greater volume of training to be completed during a set time period, compared with 60, 90, or 120 second rest period. This is important since training volume is believed to play a role in muscle hypertrophy, particularly amongst strength athletes/bodybuilders who have been training for a period of years, and it has been suggested that these individuals may require increased training volumes to further stimulate the hormonal response to training (Cadore et al 2008).

In addition, shorter rest intervals are known to result in greater average power production across the workout (Paulo et al., 2012). In effect the shorter rest period results in a greater average intensity across the workout, due to the reduced rest interval, which may provide an additional stimulus to muscle hypertrophy.

Interestingly, when researchers (de Souza-Jr et al., 2011) compared the effects of a decreasing rest interval (2mins decreasing to 30secs over 8 weeks) with a constant interval (2mins) amongst subjects consuming creatine (both groups) they found a greater increases in cross sectional area in the decreasing interval (DI) group compared with the constant interval (CI) group for both the Upper arm (13.8% CI vs 20.8% DI) and the thigh (18.8% CI vs 27.5% DI). Although the cross sectional area increases were not significantly different between the groups the effect size was greater for the DI group suggesting that creatine may be more beneficial when utilising short rest intervals. Although it is not completely clear why creatine showed a possible greater benefit to muscle hypertrophy in the DI group it may be that creatine enhanced recovery during the short rest periods allowing greater work to be completed, which may further enhance the benefits of short rest intervals.

Muscle Fibre Microtrauma following different rest intervals

Muscle fibre microtrauma - whereby tiny microscopic tears occur in muscle fibres following strength/resistance training - is considered to play a role in muscle hypertrophy. When researchers looked at the effects of different rest intervals (60,90,120 & 180 seconds) on muscle damage they found that similar amounts of damage occurred to muscle fibres independent of rest interval (Machado et al., 2011). The researchers suggested that this indicated that the volume of training is a key determinant of muscle damage amongst trained subjects. Since shorter rest intervals allow a greater amounts of work to be completed in a set time they may increase microtrauma by allowing a greater training volume to be completed. Therefore, in the case of bodybuilders where the desired outcome of training is to stimulate muscle growth through overstressing muscle fibres it appears that shorter recovery periods are more beneficial since they allow a greater work volume.

Summary

  • Shorter rest intervals (30-60secs) increase the anabolic response to strength training
  • Shorter rest intervals may be more beneficial to highly resistance trained individuals
  • Allows a greater average power production across the workout
  • Creatine may enhance the benefits of short rest intervals
  • The rest interval duration doesn't influence the level of muscle fibre microtrauma, however, shorter rest intervals allow a greater volume to be completed in a set time which may increase the level of muscle fibre microtrauma

 

 

References

Bottaro M, Martins B, Gentil P, Wagner D. (2009) Effects of rest duration between sets of resistance training on acute hormonal responses in trained women. J Sci Med Sport. 2009 Jan;12(1):73-8. Epub 2008 Feb 21.

Cadore EL, Lhullier FL, Brentano MA, da Silva EM, Ambrosini MB, Spinelli R, Silva RF, Kruel LF. (2008) Hormonal responses to resistance exercise in long-term trained and untrained middle-aged men. J Strength Cond Res. 2008 Sep;22(5):1617-24.

Machado M, Koch AJ, Willardson JM, Pereira LS, Cardoso MI, Motta MK, Pereira R, Monteiro AN. (2011) Effect of varying rest intervals between sets of assistance exercises on creatine kinase and lactate dehydrogenase responses. J Strength Cond Res. 2011 May;25(5):1339-45.

Paulo CA, Roschel H, Ugrinowitsch C, Kobal R, Tricoli V. (2012) Influence of different resistance exercise loading schemes on mechanical power output in work to rest ratio - equated and - nonequated conditions. J Strength Cond Res. 2012 May;26(5):1308-12.

Rahimi R, Qaderi M, Faraji H, Boroujerdi SS. (2010) Effects of very short rest periods on hormonal responses to resistance exercise in men. J Strength Cond Res. 2010 Jul;24(7):1851-9.

de Souza TP Jr, Fleck SJ, Simão R, Dubas JP, Pereira B, de Brito Pacheco EM, da Silva AC, de Oliveira PR. (2010) Comparison between constant and decreasing rest intervals: influence on maximal strength and hypertrophy.J Strength Cond Res. 2010 Jul;24(7):1843-50.

de Souza TP Jr, Willardson JM, Bloomer R, Leite RD, Fleck SJ, Oliveira PR, Simão R.(2011) Strength and hypertrophy responses to constant and decreasing rest intervals in trained men using creatine supplementation.J Int Soc Sports Nutr. 2011 Oct 27;8(1):17.

Villanueva MG, Villanueva MG, Lane CJ, Schroeder ET. (2012) Influence of Rest Interval Length on Acute Testosterone and Cortisol Responses to Volume-Load Equated Total Body Hypertrophic and Strength Protocols. J Strength Cond Res. 2012 Jul 12. [Epub ahead of print]

Willardson JM. (2006) A brief review: factors affecting the length of the rest interval between resistance exercise sets. J Strength Cond Res. 2006 Nov;20(4):978-84.