Range of motion is simply the degree of movement at a joint. Training with a full range of motion means moving a joint through its full potential during an exercise. Partial range of motion training involves intentionally shortening this movement. Many trainees firmly believe in one of two approaches. Some strongly advocate for full range of motion, believing it superior for muscle growth and viewing partial reps as primarily ego-driven.
Others prefer partial reps, believing they allow for lifting heavier weights or maintaining constant muscle tension by keeping the weight in the mid-range. They may even cite IFBB pro bodybuilders who utilize partials and experience significant gains.
Both sides have valid points. Let’s examine the arguments for partial range of motion training.
The first argument is that partials allow for heavier weights, leading to greater muscle tension. While lifting heavier is possible with a shorter range of motion, it doesn’t necessarily equate to more tension on the muscle. The extra weight comes at the expense of reduced distance moved.
For instance, if you squat 225 pounds for three sets of eight reps, and then halve the range of motion to squat 315 pounds, it might appear you’re handling more workload. However, the reduced distance means less overall work. The increased weight doesn’t compensate for the loss of distance in terms of hypertrophy.
Trading range of motion for weight is generally disadvantageous, though there are exceptions we’ll explore later.
The second argument for partials, maintaining constant muscle tension, is more compelling. This involves stopping just short of full lockout, keeping the muscle continuously engaged in the active mid-range. Full lockout can provide a brief rest and tension release, potentially hindering growth.
A 2017 study supports this. Researchers compared full range of motion skull crushers with half range of motion skull crushers focusing on the mid-range. The full range group experienced a tension break at the top of each rep, while the partial group maintained continuous triceps engagement. After eight weeks, the partial group showed significantly greater muscle growth, almost double the gains.
This suggests constant tension can be beneficial, especially on certain movements like skull crushers and dumbbell flies where the top of the range of motion is relatively easy. Stopping just short of lockout can be advantageous. However, this likely applies mainly to free weight isolation exercises. Cables and machines often provide constant tension, making a full stretch and squeeze more beneficial.
It’s important to note that of the six studies on range of motion and hypertrophy, this is the only one favoring partials. This is likely due to the unique benefits of constant tension on single-joint, free-weight isolation exercises like skull crushers.
The final argument for partials involves the observation that many IFBB pro bodybuilders utilize them. However, classic era bodybuilders often used full range of motion. While some modern pros may favor partials, it’s difficult to isolate this variable as the sole cause of their success. Other factors, like genetics, nutrition, and supplementation, play significant roles.
While such anecdotes aren’t worthless, stronger evidence exists. A systematic review examined six studies on range of motion and muscle growth. Four lower body studies favored full range of motion. Upper body studies showed conflicting results, with one finding no difference between full and partial range curls and the other favoring partials (the skull crusher study).
The evidence suggests full range of motion is generally better for muscle growth, especially in the legs. A study by Bloomquist et al. compared heavier partial squats to lighter deep squats. Despite being lighter, deep squats resulted in greater muscle growth across the quadriceps.
A good rule of thumb is to prioritize full range of motion, achieving a reasonably full stretch and contraction. However, this shouldn’t be taken to extremes. Respecting individual mobility limitations is crucial. Squatting to just below parallel is likely as effective as squatting deeper for quad growth.
Exceptions to the full range of motion rule exist. Partials can be a useful advanced technique for isolation exercises, eliminating the easy portions of the range of motion. Cutting out the bottom of lateral raises or not fully locking out skull crushers are examples.
Extended sets with partials after reaching failure can also be effective for stubborn body parts, particularly on the last set. For powerlifters and powerbuilders, the bench press and deadlift may also warrant exceptions. A powerlifting arch on the bench press, while limiting range of motion, can be a worthwhile trade-off, especially when combined with other chest exercises.
Similarly, a sumo deadlift stance, even with slightly reduced range of motion, can be a smart powerlifting strategy, especially when combined with other exercises.
While full range of motion is generally preferable, incorporating both approaches can yield optimal results.
