Effects of Rest Interval Length on Muscle Hypertrophy in Amateur Bodybuilders
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Rest interval length is a routine programming variable in bodybuilding, yet its chronic influence on hypertrophy in trained recreational competitors remains debated. This study compared 60 s, 90 s, and 180 s inter-set rest intervals during a supervised 10-week hypertrophy-oriented program in amateur bodybuilders. Thirty-six natural amateur bodybuilders (24 men and 12 women) with at least two years of resistance-training experience were randomly assigned to one of three rest-interval conditions. All groups completed the same five-day split routine, identical exercise order, matched repetition targets, and progressive overload; the only programmed difference was rest duration. Primary outcomes were ultrasound-derived muscle thickness of the vastus lateralis and biceps brachii. Secondary outcomes were bench press and back squat one-repetition maximum (1RM), body composition, and cumulative training volume. Assumption checks included the Shapiro-Wilk and Levene tests. Between-group differences in change scores were examined using one-way analysis of variance with Tukey-adjusted post hoc comparisons, and within-group changes were tested with paired-samples t tests. Results: Baseline characteristics did not differ between groups (all p > 0.80). Vastus lateralis thickness increased by 3.9%, 8.0%, and 8.8% in the 60 s, 90 s, and 180 s groups, respectively. Biceps brachii thickness increased by 4.2%, 7.4%, and 8.9%, respectively. Group effects were significant for vastus lateralis change (F = 39.81, p < 0.001, eta squared = 0.71) and biceps brachii change (F = 28.00, p < 0.001, eta squared = 0.63), with both 90 s and 180 s outperforming 60 s. Bench press and squat 1RM improved in all groups, but strength gains were larger with 90 s and 180 s rest. Cumulative training volume was also higher in the longer-rest conditions and was positively associated with the composite hypertrophy response (r = 0.59, p < 0.001). In amateur bodybuilders, moderate-to-long rest intervals appear to support superior hypertrophy and strength development compared with 60 s rest, largely through better preservation of weekly training volume. A 90 s interval seems to provide the most practical balance between session efficiency and adaptation.
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1. N. A. Ratamess, B. A. Alvar, T. K. Evetoch, T. J. Housh, W. B. Kibler, W. J. Kraemer, and N. T. Triplett, "Progression models in resistance training for healthy adults," Med. Sci. Sports Exerc., vol. 41, no. 3, pp. 687-708, 2009, doi: 10.1249/MSS.0b013e3181915670. DOI: https://doi.org/10.1249/MSS.0b013e3181915670
2. W. J. Kraemer and N. A. Ratamess, "Fundamentals of resistance training: progression and exercise prescription," Med. Sci. Sports Exerc., vol. 36, no. 4, pp. 674-688, 2004, doi: 10.1249/01.MSS.0000121945.36635.61. DOI: https://doi.org/10.1249/01.MSS.0000121945.36635.61
3. B. J. Schoenfeld, "The mechanisms of muscle hypertrophy and their application to resistance training," J. Strength Cond. Res., vol. 24, no. 10, pp. 2857-2872, 2010, doi: 10.1519/JSC.0b013e3181e840f3. DOI: https://doi.org/10.1519/JSC.0b013e3181e840f3
4. W. J. Kraemer et al., "American College of Sports Medicine position stand. Progression models in resistance training for healthy adults," Med. Sci. Sports Exerc., vol. 34, no. 2, pp. 364-380, 2002, doi: 10.1097/00005768-200202000-00027. DOI: https://doi.org/10.1097/00005768-200202000-00027
5. B. F. de Salles, R. Simao, F. Miranda, J. S. Novaes, A. Lemos, and D. Willardson, "Rest interval between sets in strength training," Sports Med., vol. 39, no. 9, pp. 765-777, 2009, doi: 10.2165/11315230-000000000-00000. DOI: https://doi.org/10.2165/11315230-000000000-00000
6. M. Henselmans and B. J. Schoenfeld, "The effect of inter-set rest intervals on resistance exercise-induced muscle hypertrophy," Sports Med., vol. 44, no. 12, pp. 1635-1643, 2014, doi: 10.1007/s40279-014-0228-0. DOI: https://doi.org/10.1007/s40279-014-0228-0
7. J. Grgic, B. Lazinica, P. Mikulic, J. W. Krieger, and B. J. Schoenfeld, "The effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy: A systematic review," Eur. J. Sport Sci., vol. 17, no. 8, pp. 983-993, 2017, doi: 10.1080/17461391.2017.1340524. DOI: https://doi.org/10.1080/17461391.2017.1340524
8. J. Grgic, B. J. Schoenfeld, M. Skrepnik, T. B. Davies, and P. Mikulic, "Effects of rest interval duration in resistance training on measures of muscular strength: A systematic review," Sports Med., vol. 48, no. 1, pp. 137-151, 2018, doi: 10.1007/s40279-017-0788-x. DOI: https://doi.org/10.1007/s40279-017-0788-x
9. R. C. Alves, J. Prestes, A. Enes, W. M. Moraes, F. de Salles Painelli, E. A. Nunes, B. B. Ribeiro, B. J. Schoenfeld, and D. Cyrino, "Training programs designed for muscle hypertrophy in bodybuilders: A narrative review," Sports, vol. 8, no. 11, Art. no. 149, 2020, doi: 10.3390/sports8110149. DOI: https://doi.org/10.3390/sports8110149
10. W. J. Kraemer, B. J. Noble, M. J. Clark, and B. W. Culver, "Physiologic responses to heavy-resistance exercise with very short rest periods," Int. J. Sports Med., vol. 8, no. 4, pp. 247-252, 1987, doi: 10.1055/s-2008-1025663. DOI: https://doi.org/10.1055/s-2008-1025663
11. R. Buresh, K. Berg, and J. French, "The effect of resistive exercise rest interval on hormonal response, strength, and hypertrophy with training," J. Strength Cond. Res., vol. 23, no. 1, pp. 62-71, 2009, doi: 10.1519/JSC.0b013e318185f14a. DOI: https://doi.org/10.1519/JSC.0b013e318185f14a
12. J. P. Ahtiainen, A. Pakarinen, M. Alen, W. J. Kraemer, and K. Hakkinen, "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., vol. 19, no. 3, pp. 572-582, 2005, doi: 10.1519/15604.1. DOI: https://doi.org/10.1519/00124278-200508000-00015
13. J. M. Willardson and L. N. Burkett, "A comparison of 3 different rest intervals on the exercise volume completed during a workout," J. Strength Cond. Res., vol. 19, no. 1, pp. 23-26, 2005, doi: 10.1519/R-13853.1. DOI: https://doi.org/10.1519/00124278-200502000-00005
14. J. M. Willardson and L. N. Burkett, "The effect of rest interval length on bench press performance with heavy vs. light loads," J. Strength Cond. Res., vol. 20, no. 2, pp. 396-399, 2006, doi: 10.1519/R-17735.1. DOI: https://doi.org/10.1519/00124278-200605000-00027
15. N. A. Ratamess, M. J. Falvo, G. T. Mangine, J. R. Hoffman, A. D. Faigenbaum, and J. Kang, "The effect of rest interval length on metabolic responses to the bench press exercise," Eur. J. Appl. Physiol., vol. 100, no. 1, pp. 1-17, 2007, doi: 10.1007/s00421-007-0394-y. DOI: https://doi.org/10.1007/s00421-007-0394-y
16. H. Miranda, S. J. Fleck, R. Simao, A. C. Barreto, E. H. M. Dantas, and J. Novaes, "Effect of two different rest period lengths on the number of repetitions performed during resistance training," J. Strength Cond. Res., vol. 21, no. 4, pp. 1032-1036, 2007, doi: 10.1519/R-21026.1. DOI: https://doi.org/10.1519/00124278-200711000-00009
17. G. Senna, B. F. de Salles, J. Prestes, R. A. Mello, and R. Simao, "Influence of two different rest interval lengths in resistance training sessions for upper and lower body," J. Sports Sci. Med., vol. 8, no. 2, pp. 197-202, 2009, doi: not assigned.
18. H. Miranda, R. Simao, L. M. Moreira, R. A. de Souza, J. A. A. de Souza, B. F. de Salles, and J. M. Willardson, "Effect of rest interval length on the volume completed during upper body resistance exercise," J. Sports Sci. Med., vol. 8, no. 3, pp. 388-392, 2009, doi: not assigned.
19. B. J. Schoenfeld, Z. K. Pope, F. M. Benik, G. M. Hester, J. Sellers, J. L. Nooner, J. A. Schnaiter, K. E. Bond-Williams, A. S. Carter, C. L. Ross, B. L. Just, and M. Henselmans, "Longer interset rest periods enhance muscle strength and hypertrophy in resistance-trained men," J. Strength Cond. Res., vol. 30, no. 7, pp. 1805-1812, 2016, doi: 10.1519/JSC.0000000000001272. DOI: https://doi.org/10.1519/JSC.0000000000001272
20. N. A. Burd, A. M. Holwerda, K. C. Selby, D. W. D. West, A. W. Staples, N. E. Cain, J. G. A. Cashaback, J. R. Potvin, S. K. Baker, and S. M. Phillips, "Resistance exercise volume affects myofibrillar protein synthesis and anabolic signaling molecule phosphorylation in young men," J. Physiol., vol. 588, no. 16, pp. 3119-3130, 2010, doi: 10.1113/jphysiol. 2010.192856. DOI: https://doi.org/10.1113/jphysiol.2010.192856
21. N. A. Burd, D. W. D. West, A. W. Staples, P. J. Atherton, J. M. Baker, D. R. Moore, A. M. Holwerda, G. Parise, M. J. Rennie, S. K. Baker, and S. M. Phillips, "Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men," PLoS One, vol. 5, no. 8, Art. no. e12033, 2010, doi: 10.1371/journal.pone.0012033. DOI: https://doi.org/10.1371/journal.pone.0012033
22. F. Damas, S. M. Phillips, C. A. Libardi, F. C. Vechin, M. E. Lixandrao, P. R. Jannig, L. A. R. Costa, A. V. N. Bacurau, T. Snijders, G. Parise, V. Tricoli, H. Roschel, and C. Ugrinowitsch, "Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage," J. Physiol., vol. 594, no. 18, pp. 5209-5222, 2016, doi: 10.1113/JP272472. DOI: https://doi.org/10.1113/JP272472
23. R. W. Morton, S. Y. Oikawa, C. G. Wavell, N. Mazara, C. McGlory, J. Quadrilatero, B. L. Baechler, S. K. Baker, and S. M. Phillips, "Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men," J. Appl. Physiol., vol. 121, no. 1, pp. 129-138, 2016, doi: 10.1152/japplphysiol. 00154.2016. DOI: https://doi.org/10.1152/japplphysiol.00154.2016
24. B. J. Schoenfeld, M. D. Peterson, D. Ogborn, B. Contreras, and G. T. Sonmez, "Effects of low- vs. high-load resistance training on muscle strength and hypertrophy in well-trained men," J. Strength Cond. Res., vol. 29, no. 10, pp. 2954-2963, 2015, doi: 10.1519/JSC.0000000000000958. DOI: https://doi.org/10.1519/JSC.0000000000000958
25. B. J. Schoenfeld, B. Contreras, J. Krieger, J. Grgic, K. Delcastillo, R. Belliard, and A. Alto, "Resistance training volume enhances muscle hypertrophy but not strength in trained men," Med. Sci. Sports Exerc., vol. 51, no. 1, pp. 94-103, 2019, doi: 10.1249/MSS.0000000000001764. DOI: https://doi.org/10.1249/MSS.0000000000001764