There are a lot of different approaches to training. Some are very universal and can be effective for a great many people. Others should either be largely avoided or will only apply to a select few. On occasional, there can be an approach or technique that will be useful and effective in some situations, but completely counterproductive in others. The practice of doing partial repetitions, reps that fall short of a complete range of motion, is one of those approaches. Under some circumstances partials can be an effective training tool. Under others, it can be a complete waste of time and energy and even dangerous. Here is some information on how, when, and if you should use partials in your training.
We’ve all seen the guy in the gym with the overloaded leg press machine doing 4-6 inch reps. Or maybe you’ve seen someone doing bench press who acts like if he comes all the way down and touches the bar to his chest, he will be burned to a crisp! While there are times when doing partial reps can be a good thing, if the only goal is to simply make the movement easier, or to be able to use a greater amount of weight than you can properly handle, then it’s the ego and not the muscles that are being trained. Doing partial movements just for the cosmetic effect of having more weight on the bar or machine won’t give you a better physique. Often, extra momentum is being used along with this which takes the stress off of the muscle. Plus, if a weight that is too heavy is taken beyond this shortened range (which is often the mechanically advantaged section of the movement) it can be disastrous. You should never select your weight based on trying to impress anyone.
All repetitions are tools. They are the building blocks of your workout and how, when, and whey they are done programs your body for the changes you desire. Partial reps (like cheat reps) should not be used simply to make a movement easier or to increase the load by incorporating altered or improper form. There are however a number of situations when partial reps may be as good or even better than full, normal reps for certain, specific goals:
Strength Targeting: Partial reps can be used effectively to improve or increase strength at a key section of an exercise. Strength athletes have long used power racks to do lockouts or partial movements on limited controlled ranges of exercises like bench presses and overhead presses. Through focusing on a section of a movement in which they were having trouble by doing some heavier, partial movements, an athlete can increase their strength in that area which would then ideally transfer over to the regular, full-range exercises. Using partials can be a great way to help blast through a sticking point.
Growth Targeting: At times using partial reps can create a more targeted effect on a specific muscle or body area allowing for improved growth. For example, focusing on the upper half of a glute machine press may effect a greater feel and response in the glute. Doing those 6 inch leg press may better work the “tear drop” or lower quad area by using those heavier weight than would full reps with lighter reps. This principle is more instinctive than anything, but the feel of a movement to a given area can definitely be effected by the range of motion. In some cases for advanced physique athletes this is used to target improving or increasing development in that area.
Pain Avoidance: Partial or limited range movements may be ideal to use when normal full range movements cause excessive pain or injury due to joint or mobility issues. For some people or in certain situations, a full range of motion may not be possible or cause undue pain or risk of injury. Controlled partial movements within a more defined range of motion can often still be used to effectively work the muscle. This is something that may be an option for older athlete or someone coming off an injury (after they have been cleared to resume training of course). Care must always be taken with the amount of weight used and of course any injury should be checked by medical professionals.
Burns: Doing a series of partial reps at the end of a set of normal reps is called “burns” and is a great way to utilize partials. For example, after a normal set of dumbbell presses, you can do 5-6 more half or partial reps with the same weight to make the set even tougher. Burns are great for targeting stubborn muscle groups by adding another level of intensity to the set, allowing you to go beyond normal failure. They should only be done for 1-2 sets on 1-2 exercises per body part, but they can be quite effective at shocking the muscles in an effort to produce better results. They will cause excessive fatigue and muscle burn (hence the name) during their use so be careful to use them only on movements where they would be safe. (Don’t get stuck on the bench after a set of burns!)
Natural Range: Not everyone has the same natural range of motion. Our bodies can be engineered quite differently from one person to the next. Doing a full squat below parallel may be easy and seem natural for some people, while anything lower that barely reaching parallel may be next to impossible for someone else. In general you should work within your own natural range of motion. This may be a bit more or less than someone else or what is considered “standard”. Care should be taken not to place undue stress on a joint or muscle by going beyond a safe range and creating stress in a unwelcome area. As long as you’re working within your own natural range, it’s OK if it may at times be a bit different than what someone else is doing.
Continuous Tension: One technique popular with some more advanced trainers is to slightly reduce the range of motion so that the weight/resistance is constantly felt on the working area. This principle of continuous tensions requires a great deal of control, and momentum should be eliminated as much a possible. Because many movements cause a shift in leverage that can reduce the tension on the working muscle (like with barbell curls for example) the movement is shortened during a set or two in order to better target and effect the muscle area. It is not a substitute for normal range training, just an occasional or additional variation to push towards improved gains in an area that may not be responding ideally.
Partial repetitions can be a useful and effective part of your training program. You just need to make sure that you are using them at the proper times and in the correct ways. Never use them for ego gratification. Only use them in ways that can help some aspect of your training or physique progress. If employed with care, partial reps can be another tool to help you push to a new level.
Photo: Terry Goodlad Model: Ramon Ramjit-Munoz