Most of the time you see people in the gym doing partial reps it’s not for any of the reasons below, it’s because ego has gotten in the way and they half ass (literally) their sessions, and get the results they deserve.
The thing is partial reps are useful in some circumstances and when programmed properly.
Here are 3 instances where partial reps can help your training.
Getting back to training post injury can be aided by introducing partial reps, allowing your to work through pain free ranges of movement, building strength as you gradually increase the range you work in. From my own experience, re-introducing the deadlift via high rack pulls from above the knee, then below the knee, then trap bar deadlifts and finally back to full range deadlifts. Each time progressing only when I was able to do so completely pain free. For clients, I’ve used high box squats, then lower box squats and finally bodyweight squats to parallel, then deeper if they are able.
Break through sticking points
Some exercises will have you failing at certain points. For example on a DB press or bench press you may find yourself pressing easily off your chest and getting “stuck” about half way up where your triceps need to kick in to finish. You can fix this issue by setting up the safety bars at your sticking point and pressing just through the top end of the movement. You get strong in the range of movements you work in. So to push through sticking points work more in the “sticky” ranges. But to get a full range in which you are strong, you still need those full reps.
Work around poor mobility
Occasionally, I’ll have a client who just doesn’t have the ability to get into a deep squat, or can’t deadlift from the floor. The first of these is usually a mobility issue, the second is more often a structural issue and they just can’t get a flat back at the bottom of the lift. Slightly different issues, same fix.
For the squatter you can use a box that allows squatting to the depth that can be controlled well. As strength and mobility improve the box gets lower and eventually, in most cases, the box goes and good, deep, box free squats are the outcome.
For the deadlift, no amount of mobility work is going to fix the issue. You have to remember that the height of the bar off the floor is pretty arbitrary and not every body type is going to be able to get shoehorned into the correct position. So we make the bar height fit the lifter, not the other way around.
Raising the bar and plates up on to boxes or onto safety bars by a few inches is enough to allow a good position to be gained and pain free lifting can recommence.