Highway to Huge: High or Low Reps?

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Highway to Huge: High or Low Reps?

by: Robbie Durand

If you look at many fitness websites, you will see such programs as “100-Rep Hell” or the “3 Minute Set” programs being advocated at the ultimate program for muscle size. Some bodybuilders advocate high repetitions for muscle growth where others advocate low repetitions, but there is little research to prove which repetition scheme works the best for muscle growth. Results of these studies are conflicting, with some studies finding superiority for heavier load training and others showing no significant differences between high repetition protocols taken to fatigue compared to lower repetitions taken to fatigue. In the past, researchers thought the only way to stimulate muscle growth was to use tension overload, which means they would just overload the muscle with weights, but then the researchers started examining blood occlusion studies which used a very light weight but it induced a huge metabolic stress.  Something interesting happened with blood occlusion training, the muscles of the subjects grew with a very low amount of weight used, which caused researchers to start examining metabolic stress for muscle hypertrophy.

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Low Repetitions vs High Repetitions for Muscle Growth: Which is Better?

Researchers examined 18 young men experienced with resistance training experience, they were matched according to baseline strength, and then randomly assigned to 1 of 2 experimental groups:

-A low-load resistance training routine where 25-35 repetitions were performed per set per exercise, or

-A high-load resistance training routine where 8-12 repetitions

were performed per set per exercise.

The resistance training protocol consisted of 3 sets of 7 exercises per session targeting all major muscle groups of the body. Training was carried out three times per week on non-consecutive days, for eight total weeks. All other resistance training variables (e.g., exercises performed, rest, repetition tempo, etc.) were held constant. The training interventions lasted eight weeks with subjects performing three total body workouts per week.

At the end of eight weeks, when the researchers crunched all the data, both routines increased muscle growth similarly with no significant differences between the two groups. These results run contrary to accepted hypertrophy training guidelines, which profess that loads of at least 65% are necessary to stimulate muscle growth in well-trained individuals.

In terms of strength, although low load did increase maximal muscle strength, the heavier weight, lower rep routine resulted in greater increases in strength. It should be noted that the greater increase in bench-press strength for the high load method led to their lifting slightly higher mean loads (~2 kg) compared with low weight. 1RM bench press increased by 6.5% vs. 2.0% for the low load routine. In conclusion, the study goes against the popular belief that you can only build muscle with heavy weights. The results suggest that low-load training can be an effective method to increase muscle hypertrophy of the extremities in well-trained men. The gains in muscle size from low-load training were equal to that achieved with training in a repetition range frequently recommended for maximizing muscle hypertrophy. On the other hand, if maximizing strength gains is of primary importance, then heavier loading should be employed to the exclusion of lower load training.

The primary take-home points from the study are as follows:

  • Gains in muscle mass are about the same regardless of repetition range provided training is carried out to muscle failure.
    • To build maximal strength requires the use of heavy loading
    • Muscle endurance is best obtained from the use of light loads
Muscular torso and arms. Bodybuilder with huge muscles. Strong man’s torso. Picture of muscular torso, arms and abs.
Muscular torso and arms. Bodybuilder with huge muscles. Strong man’s torso. Picture of muscular torso, arms and abs.

Training to Fatigue with Light Weights Stimulates Muscle Growth

Previously research has shown that performing resistance exercise to complete fatigue, regardless of load, results in similar increases in skeletal muscle mass, fiber size and strength. However, these studies were performed in untrained subject’s. Researchers wanted to re-examine the impact of resistance exercise using lite weights.

Researchers had forty-nine resistance trained men randomly allocated into:

– a high-repetition-low-load group (30-50% 1RM: 20-25 repetitions/set) or

– a low-repetition-high-load group (70-90% 1RM: 8-12 repetitions/set) and performed 12 week of whole-body resistance exercise. Groups were matched at baseline for age, lean body mass, training experience, and strength for leg press, bench press, knee extension and shoulder press.

In response to the 12-week intervention, muscular strength increased for all exercises in both groups, with change in bench press significantly greater in the heavier weight group. Lean body mass, type I and type II muscle fiber cross sectional area increased following training with no significant differences between groups and no change in fiber type distribution.

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All hormones (cortisol, free testosterone, total testosterone, dihydrotestosterone, dehydroepiandrosterone, luteinizing hormone, free insulin-like growth factor 1, total insulin-like growth factor 1 and growth hormone) increased as a result of an acute bout of resistance exercise. After the numbers were studies, no hormone at any time point was significantly correlated with the change in hypertrophy or strength. These data show that when resistance exercise is performed to complete fatigue neither repetition-load nor post-resistance exercise hormone concentrations are significant determinants of gains in strength or hypertrophy in resistance trained individuals.

Key Points: The researchers found that high repetition exercise taken to fatigue can stimulate muscle growth to a similar extent as heavy weight lifting, but strength gains are superior with heavy weights.  So mixing up your workouts with high and low repetitions can be great for increasing muscle mass.

Andrew C. Fry, The Role of Resistance Exercise; Intensity on Muscle Fibre Adaptations; Sports Med 2004; 34 (10): 663-679.

Nishimura A, Sugita M, Kato K, Fukuda A, Sudo A, Uchida A. Hypoxia increases muscle hypertrophy induced by resistance training. Int J Sports Physiol Perform. 2010 Dec;5(4):497-508.

Yasuda T, Ogasawara R, Sakamaki M, Bemben MG, Abe T. Relationship between limb and trunk muscle hypertrophy following high-intensity resistance training and blood flow-restricted low-intensity resistance training. Clin Physiol Funct Imaging. 2011 Sep;31(5):347-51.

Schoenfeld BJ, Peterson MD, Ogborn D, Contreras B, Sonmez GT. Effects of Low-Versus High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men. J Strength Cond Res. 2015 Apr 3.

Schoenfeld BJ, Wilson JM, Lowery RP, Krieger JW. Muscular adaptations in low-versus high-load resistance training: A meta-analysis. Eur J Sport Sci. 2014 Dec 20:1-10. [Epub ahead of print]

 Schoenfeld BJ, Peterson MD, Ogborn D, Contreras B, Sonmez GT. Effects of Low- Versus High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men. J Strength Cond Res. 2015 Apr 3.

Morton1, S. Oikawa1, N. Mazara1, C. Wavell1, C. McGlory1, J. Quadrilatero2, S. Phillips1. Repetition-load and systemic hormone concentrations do not determine resistance training-mediated adaptations in trained young men. The Biomedical Basis of Elite Performance 2016 (London, UK) (2016) Proc Physiol Soc 35

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