Whereas some would argue that a full range of movement is required for the best result from a rep, there are others who would say partial reps have their place in mass muscle building. There are several variables you can apply to your workout sessions, no matter what your aims are. When it comes to mass building, you can vary the amount of protein and calories you consume and burn off, you can vary the amount you lift, the grip, machine or method. But one thing you might have overlooked is the range of movement in each rep.
So many online guides and coaches meticulously demonstrate the exact way you should perform an exercise but rarely will explain the benefits of performing only a partial range of movement.
A lockout, using the example of a bicep curl, is when you fully stretch out your arm. You’ll have been told before to not ‘lock out’ your knees when performing a leg press or squat, meaning you should leave a slight bend in your leg so there is some give in your joints when keeping your balance.
When it comes to partial reps, there is a question of how much extra strain is placed on the muscle you’re targeting – and how this affects the stress on your joint. It may be argued that avoiding lockouts spares your joints – in the example of a bicep curl, your elbow will be spared more than when you perform a full range. For the targeted muscle, you will experience greater strain and a greater build up of lactic acid because you will not get the rest (however brief) by locking out between reps.This could well be taken as a negative for partial reps, given how much harder lactic acid makes your reps.
In the favour of partial reps, let’s go back to the effect they have on your joints and how your body may well benefit from them. Using the example of compound lifts like squats or leg presses, when you lift all the way (with your glutes close to the plate or floor) this can cause significant issues for your knees and lower back in the long run. When you squat from a parallel position, this means you utilise the posterior chain more, drawing on the glutes and hamstrings so that your knees are spared.
In essence, weightlifting is a great stress on your body as you are literally burdening your muscles in order to break and regrow them. If the aim is bigger muscles, though, where’s the harm in avoiding the long term harm? Where feasible, if partial reps can spare you damage to your connective tissue, or you have suffered an injury, partial reps may be the way forward to work the muscle but not the joints (as much as possible).
Partial reps are also used by bodybuilders because they mean you can lift a greater amount of weight. Think about the last time you tried to increase the amount you bench pressed and came close but not all the way to a full rep. This incomplete attempt will not have hit all the same muscle fibres as a full range rep would have, but it will have put the ones it did hit to greater use. The logic here is to do the same on purpose.
By stacking on a heavier weight and committing to a shorter range of movement you will be able to perform more reps. Taking this approach, you should increase the number of sets and stick to a low number of reps, so that you can place the emphasis on lifting more. Again, without locking out, you won’t last as long lifting this way.
The fact is, that to hit the most muscle groups, which is proven to be the most effective way to develop mass muscle, a full range of movement is the way to do it. The price is lifting a slightly lower weight than you would be able to with a partial rep. So let’s compromise and find a place for both.
If you’re playing the long game, you can utilise partial reps to build your overall strength, therefore developing your strength in the full range of the exercise.