Most of us have, at one time or another, been warned by some medico not to lift for a few days, weeks, or months so that we can heal up from whatever ding or dent we've suffered in the gym.
More often than not we nod our head in compliance, but mentally we're miming a cranking motion with one hand while the middle finger of the other hand rises to full F-You extension.
Sure, there are legitimate scenarios where we might want to think twice about returning to the gym too early (dual punctured lungs, dislocated spleen, sucking chest wound, etc.), but most of us choose, wisely or unwisely, to keep on lifting, to "work around" injuries. Most of the time this involves doing however much of our regular workouts as possible, albeit at a lighter weight.
I'm not here to weigh in on the wisdom of such a strategy. I'm just here to report on the best way to train with light weight and still keep making progress.
Many Methods, Some Better Than Others
Most lifters will work around an injury by using roughly 50% of our normal, healthy 1RM, but science tells us that lifting with that percentage doesn't increase muscle size or strength. However, you can make lifting with 50% of your 1RM an effective strategy, provided you do it the right way.
- One effective method involves training with 50% of your 1RM, but resting for only 30 seconds between sets. At least one study has shown that it works fairly well.
- Another semi-effective method involves taking 10 seconds to do the lifting, or concentric portion of the lift, while taking 4 seconds to do the lowering, or eccentric part of the lift.
- A third method was the subject of another study by Japanese researchers. They call it "resistance exercise with relatively slow movement and tonic force generation." It involves using 50% of your 1RM, but doing it so slowly that you can only muster enough energy and force to do 8 reps. For the sake of their experiment, the researchers somewhat arbitrarily decided to make both the concentric and eccentric movement takes 3 seconds, for a total of 6 seconds per rep.
Light and Slow: The Study
The scientists recruited 24 male students and had them train their legs on a leg-extension machine 3 times a week for 12 weeks. They divided them into three groups:
- The LST group did "resistance exercise with relatively slow movement and tonic force generation" (sets of 8 at 50% of 1RM, taking 3 seconds to raise the weight and 3 seconds to lower it).
- The HN group trained the conventional way, i.e., they did sets of 8 at 80% of 1RM.
- The LN group did 8 reps at 50% of their 1RM, but didn't train to failure (unlike the other two groups.)
After 12 weeks, the max strength of the LST group increased by 28% and the strength of the HN group increased by 32%, so it was pretty close. The LN group, however, only increased their strength by 16%.
As far as muscle mass, the LST group and the HN group fared equally well, while the LN group didn't grow at all.
Less Oxygen, More Muscle
The researchers theorized that oxygen depletion in muscles is a major component of increases in muscle size. When oxygen decreases, lactic acid increases, and the synthesis of growth hormone and testosterone increases as well. Since the amount of oxygen in the muscles of the LST group decreased almost as dramatically as it did in the HN group, they realized nearly equal results.
So, based on this study at least, you can still make progress during those periods when you're banged up and going full bore isn't the best idea.
- Tanimoto M, Ishii N. "Effects of low-intensity resistance exercise with slow movement and tonic force generation on muscular function in young men."
- J Appl Physiol (1985). 2006 Apr;100(4):1150-7.