Muscle Growth: High Repetitions or Heavy Weights?

Which is Better for Muscle Growth: High Repetitions or Heavy Weights? Low repetitions may be better for the ego than it is for actual muscle growth.

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Which is Better for Muscle Growth: High Repetitions or Heavy Weights?

by:Robbie Durand

A set can be defined as the number of repetitions performed consecutively without rest, whereas exercise volume can be defined as the product of total repetitions, sets, and load performed in a training session6.  Previous studies point to the metabolic stress bodybuilding-style routines, which show significant postexercise declines in ATP, creatine phosphate, and glycogen, and increases in blood lactate during exercise from performing multiple sets of 6-12 reps2.  The buildup of these metabolites has been shown to have a significant impact on anabolic processes3.   Genetic background, age, gender, and other factors have been shown to mediate the hypertrophic response to a training protocol, affecting both the rate and the total amount of gains in lean muscle mass1. Exercise-induced muscle hypertrophy is facilitated by a number of signaling pathways, several primary anabolic signaling pathways have been identified including Akt/mammalian target of rapamycin (mTOR), mitogen-activated protein kinase (MAPK).

 Greater Anabolic Signaling from Volume Training for muscle growth

carbs, infinite_labs, Muscle GrowthA study in the Scandinavian Journal of Medicine in Science and Sports that point to why you may want to incorporate more volume for muscle growth.  Researchers compared a bodybuilding type protocol which the participants performed a hypertrophy protocol in which they performed five sets of 10 repetitions; the other group performed a maximal strength protocol in which they performed 15 sets with a maximal repetition.  The exercise consisted of the leg press, and the rest period’s between sets were 3 minutes for the strength program and 2 minutes for the hypertrophy protocol.  The researchers wanted to examine in particular anabolic-signaling pathways expressed after each protocol. Here is a brief background on the anabolic signaling pathways.

1) p70S6K, most probably through mTOR, has been shown to be important in muscle protein synthesis and hypertrophy7, 8.
2.) Mitogen-activated protein kinase (MAPK) also positively regulate muscle size9.

gustavo_badell, infinite_labs, Muscle GrowthAfter each session of strength and hypertrophy sessions the researcher took a muscle biopsy after each session and examined the anabolic signaling pathways for muscle growth. The hypertrophy group performed more volume than the strength group, but the major findings of the study were that after the hypertrophic resistance exercise protocol (5 reps of 10RM) compared with the maximal strength protocol (15 sets of 1 RM) enhanced MAPK signaling in muscle.  Additionally, p38 and Erk 1/2 phosphorylation which has been previously reported to be increased after muscle hypertrophy protocols were only increased in the group that did 5 sets with 10 repetitions whereas the group performing 1 repetitions reps had no increases in these anabolic signaling pathways. In conclusion, MAPK signaling and several other anabolic signaling pathways are greater after hypertrophic than maximal strength exercise protocol. These greater increases in anabolic signaling pathways mediated from higher volume may mediate adaptations in muscle hypertrophy specific to these different types of training regimens such as bodybuilding programs10.  

1. Kraemer, WJ, Häkkinen, K, Newton, RU, Nindl, BC, Volek, JS, McCormick, M, Gotshalk, LA, Gordon, SE, Fleck, SJ, Campbell, WW, Putukian, M, and Evans, WJ. Effects of heavy-resistance training on hormonal response patterns in younger vs. older men. J Appl Physiol 87: 982-992, 1999.

2. Tesch, PA, Colliander, EB, and Kaiser, P. Muscle metabolism during intense, heavy-resistance exercise. Eur J Appl Physiol Occup Physiol 55: 362-366, 1986.
3. Kraemer, WJ and Ratamess, NA. Hormonal responses and adaptations to resistance exercise and training. Sport Med 35: 339-361, 2005.
4. Pipes, TV. Strength training and fiber types. Sch Coach 63: 67-70, 1994.
5. Westcott, WL. Strength training research: Sets and repetitions. Schol Coach 58: 98-100, 1989.
6. Schoenfeld BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res. 2010 Oct;24(10):2857-72.
7. Baar K, Esser K. Phosphorylation of p70(S6k) correlates with increased skeletal muscle mass following resistance exercise. Am J Physiol 1999: 276: C120–C127.
8. Terzis G, Georgiadis G, Stratakos G, Vogiatzis I, Kavouras S, Manta P, Mascher H, Blomstrand E. Resistance
exercise-induced Increase in muscle mass correlates with p70S6 kinase phosphorylation in human subjects. Eur J Appl Physiol 2008: 102: 145–152.
9. Haddad F, Adams GR. Inhibition of MAP/ERK kinase prevents IGF-IInducedIInduced hypertrophy in rat muscles. J Appl Physiol 2004: 96: 203–210.
10. Hulmi JJ, Walker S, Ahtiainen JP, Nyman K, Kraemer WJ, Häkkinen K. Molecular signaling in muscle is affected by the specificity of resistance exercise protocol. Scand J Med Sci Sports. 2010 Sep 9
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