Guest article written by Chris Branam
Many workout programs include repetitions done to failure. This could be with very light weight where an individual is doing repetitions numbering well over 20, or it could be done with heavy weight where failure is reached after doing as low as 1 repetition (i.e. 1 rep max). Why is it that most strength athlete programs include the latter, but not the former?
The first distinction that needs to be made for the purpose of being on common ground is the difference between muscle size and muscle strength. Hypertrophy is the process by which muscles increase in size. An increase in size usually coincides with an increase in strength, but there is not always going to be a direct ratio between the two. Surely you’ve seen a big dude at the gym struggling to hit a 400 pound back squat. His legs are huge and yet he can’t hit those numbers. But here comes a guy who is relatively small who hits it for a double. I point most people to Taner Sagir, the man in the photo above, for a good example of when strength does not always equal size. That’s nearly 380 pounds he’s holding over his head there, and he looks like he couldn’t bench 225.
So there is a difference between training for hypertrophy and training for overall strength. Though hypertrophy might occur while training for overall strength, the inverse is not necessarily true.
Let’s say you are interested in achieving bigger muscles, though. There’s certainly nothing wrong with that goal. What causes hypertrophy to occur? Two things must happen. We must have high motor unit recruitment of the muscle and the mechanical loading must be high. For example, a back squat of 85% or more will have high motor unit recruitment because the body will require all the muscle fibers to be actively working in order to move the heavy weight. Additionally, the heavy weight will cause the bar speed to be slow which means high levels of mechanical loading or–another way to think of it–higher time under tension. Let’s think of another example: bicep curls performed with light weight. At first, the motor unit recruitment is low because of the light weight, but as fatigue begins to set in, the muscle recruits more fibers in order to continue moving the weight until high motor unit recruitment is occurring. Mechanical loading then begins to increase as fatigue sets in and causes a slowing of the weight and a longer time under tension. So in the above examples, both the heavy back squat and the light bicep curl will cause hypertrophy. Only one will increase total strength, though.
For the sake of being thorough, here are some examples of what will not cause hypertrophy. First, moving a light weight quickly will cause a high level of motor unit recruitment, but will have a low mechanical loading because of the speed at which the weight is moved (e.g. power snatches with an empty barbell). Second, moving a light weight at an intentionally slow speed (the aforementioned bicep curl done slowly) will increase the mechanical loading because of the time under tension, but motor unit recruitment will be low. Lastly, as the chart below shows, the hypertrophic effect begins to fall off after 30 repetitions and one can actually experience negative effects from repetitions done in this range as central nervous system fatigue sets in.
Why else might a lifter want to avoid training to failure? The first one is probably what occurred to most of you as soon as you saw “reps to failure”: It’s exhausting! Because of the amount of muscle damage that can occur when training to failure, recovery times are greater. For an athlete like myself who trains six days a week, lengthy recovery times can cause subsequent workouts to suffer. Another huge reason weightlifters would want to avoid training to failure is that this type of training can cause type II muscle fibers to convert from type IIx to type IIa. Type IIx muscle fibers produce short explosive contractions of the muscles. In other words, these are the type of muscle fibers weightlifters want to preserve. Stopping short of fatigue can help preserve type IIx muscle fibers.
So, what is the takeaway? Strength is specific, so training with heavy weights is the best way to end up lifting heavier weights. Strength gains occur through multiple factors; hypertrophy being one of them, but not the only one. This is why in our aforementioned example, Taner Sagir could put up more weight than a man with larger muscle size. Training to failure should be avoided by strength athletes for multiple reasons:
heavy weights will increase muscle size without going to failure,
velocity-based strength training is best done without reaching failure,
recovery times are longer when training to failure,
and training to failure causes a decrease in type IIx (explosive) muscle fibers.
For bodybuilders and others who are primarily concerned with maximum hypertrophy, Chris Beardsley, Director at Strength and Conditioning Research Limited, has a recommendation:
For maximum hypertrophy, it makes sense to stay in the 5-10RM range. If it is too heavy (<5RM), it will require too many sets to get enough stimulating reps in. If it is too light (>10RM), it can lead to excessive muscle damage and slow recovery.
There’s nothing wrong with including hypertrophy work in your program, but understand that your heavy work is already achieving hypertrophy and strength gains, and that light weights carried to failure might not be worth the recovery times and deleterious effects on muscle fiber type. Stick with the heavy weights or moderate weights moved quickly for speed work and leave the light weights for someone else.