A recent study showed no significant differences in muscle protein synthesis or hypertrophy between high and low loads taken to volitional failure. The responses were similar in upper and lower body, and responses were correlated within each person (i.e., people who tended to grow more in the legs also grew more in the arms, and people who tended to respond well to higher loads also tended to respond better to lower loads).
Overview
- What did they test? A total of 20 young untrained men completed 10 weeks of training. One arm and one leg was trained with 20-25 reps at 30-40% 1-RM, while the other leg and arm was trained with 8-12 reps at 70-80% 1-RM. The researchers measured body composition, muscle size, strength, and muscle protein synthesis responses.
- What did they find? There were no significant differences in hypertrophy between high and low loads in both the arms and the legs. Hypertrophy responses were highly variable between individuals, but were correlated within individuals. People who tended to gain more size with higher loads also tended to gain more size with lower loads. Likewise, people who tended to gain more size in the arms also tended to gain more size in the legs. Muscle protein synthesis responses were also not significantly different between high and low loads, but the responses became diminished with training. Gains in size and strength were not correlated, and there was limited correlation between different measures of hypertrophy.
- What does it mean for you? There is a big genetic and biological component in how much size you’ll gain from training, and switching your rep ranges likely won’t have much impact assuming you’re training hard and taking sets to near failure. If you’re someone who gains well with lower reps, there’s a good chance you’ll respond just as well to higher reps. Also, if your legs are responsive to training, most likely your upper body will be responsive as well. Finally, measures of muscle size (like ultrasound vs. DEXA) are not well correlated, so it’s best to use multiple metrics when possible.
What’s the Problem?
Purpose
In last month’s issue of REPS, I covered a study that showed that training responses were repeatable. People who responded initially well to a training program responded well again when embarking on training after a 10-week layoff period. Likewise, people who responded poorly tended to not respond well the second time. This provided evidence supporting the anecdotal observation that some people respond better to weight training than others. Not everyone can become a champion bodybuilder or powerlifter, no matter how hard or effectively a person trains.
This brings about the question as to whether program design can impact someone’s individual responsiveness. For example, for muscle size, if you’re a good responder to lower reps, does that mean you’re a good respond to high reps too? If your lower body responds well, does your upper body also respond well? If there are innate biological differences in how different people respond in terms of hypertrophy, are there also differences in the muscle protein synthesis response? A recent study provides us some answers to these questions. In a within-subject design, researchers had young men train with high reps to failure with one limb and low reps to failure with the other limb. This was performed in both the upper and lower limbs. Let’s take a closer look at what the researchers did and what they found.
Hypothesis
The researchers hypothesized that the responses within each subject would be more similar than the responses between different subjects.
