Training throughout the whole possible working amplitude of each exercise is extremely important for every trainee, whether they are a beginner or an advanced athlete. While advanced and elite athletes periodically revolve around that principle, it is a mandatory one for beginners. For intermediate trainees the full amplitude is not so effective, due to the fast growth of the musculature, that is practically discontinued.
From a side point of view, during the exercise “barbell bicep curls” the weight is constant but the tension upon the biceps is different at every different angle of the motion. After the start of the motion, the tension constantly increases up until the point of 90 degrees, and then regressively decreases up until the end of the curl. Practically, full range of motion limits the used weights, according to the overcoming potential in the critical 90 degrees range.
This way, besides the fact the muscle contracts and stretches upon the full length of it’s range of motion, a stimulating effect is only achieved in the 80~100 degrees range, while the first and third 1/3 of the motion, the tension is insignificant.
Considering the fact that the separate parts of the movements require a differential inclusion of different muscle sectors, it’s clear why the full ROM cannot give you an overall muscle development.
It’s known that when we contract a given muscle group with a low level of intensity, all of the muscle fibers are involved but with lowered activity. And when reaching 100% intensity, the muscle fibers progressively increase their tone and efficiency.
In reality however, when we do an exercise, using a light weight the CNS doesn’t activate all the muscle fibers, but only as many as needed. The interesting thing here is that the activated fibers always contract to their maximum contraction potential.
As intensity goes up, more and more fibers are involved.
From this, we can conclude that in order to involve all the muscle fibers of the working musculature, we must apply the workload and it’s intensity when the contraction of the musculature is not past the critical point of 80~100 degrees.
How to apply the intensity in this fashion
Through the method of incomplete range of motion, we do this by completing the last part (30-40% of the whole movement) for each exercise, by avoiding the critical point. This way of training allows us to focus on the muscle sectors that are relatively inactive during the whole completion of the exercise.
In addition to that, this allows us to use bigger weights, compared to the conventional execution of the full ROM, that requires relatively lower weights.
When doing a couple of incomplete repetitions after doing a regular set, your body holds the blood and lactic acid, that slows down the energy recovery processes, leading to a hypertrophy stimulus and a feeling of better muscle pump.
From a physiological perspective, during such workloads, it’s not possible to recover the muscle energy. The almost complete lack of hyper-recovery of the muscle glycogen, even during a longer rest, leads the organism of the trainee to a quantity adaptation through hypertrophy.
The method of incomplete ROM is often done separately, using 75~85% of the possible amplitude for the given exercise. This way of exercise execution does not allow even a momentary relaxation of the activated musculature, and therefore limits the recovery during the set. This is impossible to achieve through the usual method of full ROM.
It’s recommended for this method to be used for the first half of exercises, planned for the given muscle group, and the second half is completed with full ROM respectively.
Exhaustion is even more prominent if this method is combined with the method of constant tension. Practically this principle can be applied with all exercises. If a given athlete does a barbell squat, in 4 sets of 8 reps, using 100 kg, they can complete the same sets and reps with 130-150 kg, using the incomplete ROM principle.
From a joint and muscle flexibility point of view, the full ROM is the better option, which is why, these two methods should be rationally combined. This certain combination (incomplete + complete ROM), implies the ideas of the pre-exhaustion method.
The incomplete range of motion method is effective for every part of the skeletal musculature, but especially with the leg musculature. This is because during basic exercises like Barbell squats, leg press and hack squats, we reach almost complete quadriceps relaxation at the end of each rep.
However, we should remember to not use this method excessively, and only use it for certain, individually beneficial exercises.