Low Weight, High Rep Workouts Stimulate Muscle Growth More than High Weight, Low Rep Workouts
Title: Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise
Author: Burd et al.
Journal: PLOS One
Objective: To determine the effect of resistance exercise intensity (% 1 repetition maximum—1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression.
It’s well documented and intuitive that resistance exercise stimulates skeletal muscle protein synthesis. Muscular people generally don’t get bigger or stronger sitting on their butts doing nothing; they get it playing sports and exercising.
What isn’t as clear, is how to optimize muscle growth and hypertrophy during resistance training. One commonly held belief is that high load , close to 1 rep max is the best way to stimulate skeletal muscle growth.
Recent research has suggested that you max out your myofibrillar protein synthesis at 60% of your 1-rep max.
Blood flow restriction training, which has been in use by the military for several years and is gaining traction in pro sports circles, is another indicator that max weight lifting may not optimize muscle growth. The concept here is that you place a ‘tourniquet’ on the extremity you are training, occluding vascular flow, which promotes muscle protein synthesis at much lower weights, often 20% of your 1-rep max. The army has been using this with it’s veterans with great results over the last few years.
This study sought to explore the separate influences of load (intensity) and volume on specific anabolic variables after acute resistance exercise
Fifteen men (average age 21, average BMI 24) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes:
- 90% of repetition maximum (1RM) until volitional failure (90FAIL)
- 30% 1RM work-matched to 90%FAIL (30WM)
- 30% 1RM performed until volitional failure (30FAIL)
Infusion of radiolabeled phenylalanine was used to measure rates of mixed, myofibrillar, and sarcoplasmic protein synthesis at rest, 4 hours, and 24 hours after exercise.
Exercise at 30% work matched to 90% fail induced a significant increase above rest in mixed (121%) and myofibrillar (87%) protein synthesis at 4 h post-exercise. At 24 hours after, only mixed protein synthesis was increased.
The increase in the rate of mixed and myofibrillar protein synthesis at 4 hour post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions. At 24 hours, myofibrillary protein synthesis was only elevated in 30FAIL.
The authors also looked at several signaling pathways related to muscle protein synthesis.
- There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025).
- Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise,
- Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of exercise condition.
- The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.
These results suggest that low-load, high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load, low volume.
More specifically, exercising at 30% of your 1-rep max until fail induced similar increases in myofibrillar protein synthesis at 4 hours, but was greater at 24 hours than 90% of 1-rep max until fail.
Why this occurs is still unclear, but likely associated with muscle fibre activation and type 2 fiber recruitment.
How do you incorporate this into your workout? How will professional athletes use this knowledge moving forward? This remains to be seen, but it certainly throws a wrench into some of the commonly held beliefs of resistance weight training.
Low Weight, High Rep Workouts Stimulates Muscle Growth More than High Weight, Low Rep Workouts
Burd, N. A., West, D. W., & Staples, A. W. (2010). Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men. PLoS ONE, 5(8). doi:10.1371/journal.pone.0012033