Why Do Bodybuilders Do Partial Reps?

| by Truth Seeker |

Short answer: Professional bodybuilders and the amateurs imitating them in the gym often perform partial reps, especially when working the shoulders and the chest. Why?

The official explanation behind this strategy is that partial repetitions ensure constant tension on the targeted muscle group and therefore hit the area harder. However, a good argument could be made that the gains from this maneuver are marginal at best.

The Benefits of Partial Reps According to Bodybuilders

The advocates of half-reps provide the following points to justify partial range of motion (ROM) training:

1. Constant muscular tension

The demand on the muscles drops when the joints are locked due to the increased skeletal support. By eliminating the lockout position, bodybuilders prevent the muscles from entering “rest mode”.

For instance, if you do squats without fully extending your knees at the top of the movement, your quads will get smoked quicker because the musculature is under constant strain.

Partial reps pump the muscles with blood and lactic acid faster than complete reps and allow the lifter to reach muscular fatigue, and potentially failure, with a lighter load.

The hypertrophy scholars believe that this technique generates greater stress on the musculature resulting in prominent myofibrillar and sarcoplasmic hypertrophy.

2. Reduced stress on the joints

Bodybuilders keep their elbows and knees “unlocked” to increase the tension on the muscle and to “unload” the joint. Some believe that locking out the joints is inherently bad and causes problems in the long-term; others do it because the final part of the exercise triggers pain from previous injuries.

3. To keep the muscle fresh for “important exercises”

In a bodybuilding video that I watched a long time ago, a bro-scientist said: “Don’t lock out your joints during shoulder presses. That’s all triceps. It’s better to hit the triceps with other exercises. Keep them fresh.”

His idea was that the shoulder press was going to rob his pupil’s triceps of juice that’s better spent on direct triceps work. E.g., Skull-crushers, kickbacks, push-downs…etc.

4. Muscle Targeting/Activation

The aim of bodybuilding is to develop a muscle group rather than to move iron from point A to point B. Partial reps are a reminder of that goal. A bodybuilder who is doing half-reps on the bench is thinking about pumping his chest whereas a powerlifter benching with full ROM is focused on completing the lift and is not necessarily concerned with the degree of pectoral activation and pump that he is getting from the movement.

The use of lighter loads during pumping sets facilitates that mission too. When the weight gets heavy, one is more likely to enter “survival mode” and complete the lift by any means necessary without focusing on the targeted muscle group.

5. To get a quick pump

Partial training rises the pumping effect of each repetition and floods the muscle with blood and lactic acid resulting in a burning sensation.

6. To extend a set and reach full exhaustion

You’ve probably seen the following situation: A bodybuilder is doing triceps pushdowns. He starts the exercise with full ROM repetitions, but eventually, the muscle fatigues and the triceps become too weak to lock out the elbow. The bodybuilder continues to do partials until even the strongest part of the exercise (the beginning) becomes impossible. The purpose of this technique is to reach complete muscular failure from top to bottom.

The R-E-A-L-I-T-Y

The text above would make for a great write-up in a mainstream bodybuilding magazine or website, but the reality of the situation is different.

The effectivity and the benefits of the points above aren’t as unequivocal as the believers in bodybuilding dreams and their teachers would like you to believe. Here’s the true story.

1. Locking the joints at the end of a rep is fine.

Many gullible souls still think that locking out your joints is bad. Hence why bodybuilders often claim that they are saving their precious elbows by doing partial bench presses and overhead lifts. Yet there’s nothing fundamentally unhealthy about locking your joints when lifting. They are designed for that.

Moreover, the lockout position represents the most stable biomechanical structure for supporting heavy weights. If the final range of motion is not trained, the tendons and the muscles will be weaker when forced to exert force over that amplitude. This increases the risk of injury in sports and outside of the gym.

Locking out is dangerous only if you land on a fully locked joint e.g., ending a jump with locked knees. This is why it feels natural to bend your knees after a jump as the movement of the legs acts as suspension absorbing the impact. If you look at skaters jumping off stairs, you’ll see that they squat when landing.

But this isn’t happening during strength training. The joints enter the lockout position gradually and under the support of muscular force.

2. Time under tension is just another hypertrophy concept that doesn’t have a high practical value.

If you listen to the mainstream bodybuilding doctrines, you will quickly fill your head with various training principles which sound sweet in theory, but don’t offer the promised benefits in practice. Time under tension is one of them.

Consider the following:

Person A performs all exercises over their full range of motion. This allows him/her to do more repetitions thanks to the “mini-rests” at the top.

Person B does partials to “keep the tension on the muscle” and gets a great pump.

Who’s bigger?

Exactly. There are too many factors involved to predict the end result.

In the first case, person A is spending less time under tension, but he/she is also moving the weight over a greater length. In the second scenario, person B enjoys more time under tension, but the range of motion/positive work is reduced.

Thinking that similar training calibrations can elicit hypertrophy hiding somewhere in your natural reserves is fairly naive.

3. Bodybuilders are on steroids allowing them to produce all sorts of theories.

Steroids work, brother. Studies show that non-lifters on roids gain more muscle than men who lift. (read more). The chemical substances subsidizing the growth of bodybuilders allow those “hypertrophy professors” to synthesize all kinds of muscle-building philosophies to explain their growth.

If you let them, they will flood your craniums with the most absurd statements on the planet. The base of the pro’s power will always be chemical. Without the drugs, they will all lose a monumental percentage of their size.

Similar methods have inconsequential value. Do you really think that bodybuilding would be any different if you remove partial rep training entirely? I doubt the size of the guys will change by one gram.

4. Many people use partials as an excuse to cheat.

What do unenlightened individuals do to increase their pull-up reps? They switch to “biceps hangs” instead of lowering themselves all the way down.

A while back, I met a dude at the local pull-up bars who furiously criticized me for doing dead hang pull-ups with a pause at the bottom. He called me a “cheater” and told me that I’m destroying my shoulders.

Ironically, he was doing half-rep pull-ups with his scapulae depressed the entire time – a move that is more likely to cause shoulder impingement than full ROM pull-ups because the humeral head could get “trapped” by the structures surrounding it.

Another demonstration of half-rep cheating would be many 2-plate bench competitions. Most competitors don’t lock their elbows to get more reps.

If training with a full range of motion was easier, they wouldn’t be doing that.

5. Intelligent bodybuilders who use partials rarely make it their bread and butter system.

Smart bodybuilders realize that half-rep training could be beneficial in a thin number of situations (e.g., limited equipment), but they know that full ROM training is still the most stable way to train in the long run.

How to Get the Best of Both Worlds

If you want to implement partials into your training, one of the most logical ways to do it would be a back-off set done with a lighter load after the main working sets. This way you’re getting the benefits of full ROM training combined with the pump offered by partials.

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  1. Dave

    Hey Truthseeker,
    What are your thoughts on rep tempo?

    1. Eric Robinson

      Obviously not the guy you’re looking for, but in case you don’t get an answer: It depends a little bit on your goals, but assuming we are prioritizing hypertrophy, slow and controlled is usually the recipe for success. This doesn’t have to be particularly slow, it just means that gravity should not be aiding you at any point e.g. dropping letting the bar drop to your chest and using the bounce to help on the next rep. There are super slow reps and pause reps, too. I like throwing those in sometimes, especially now that the equipment I have access to is limited. But generally speaking, as long as your muscles are working hard on both the way up and the way down, you’re doing it right.

      1. Zagor

        If the weight is heavy enough, your muscles must work hard, there’s no way around it.
        As for tempo, there’s no point in lifting the weight slowly (concentric part of the rep), you gain nothing from it except training yourself to generate less power (power is defined as ability to exert maximum force as quickly as possible).
        As for eccentric part of the rep, if you want to get really sore as quickly as possible, then you’ll do it as slowly as possible. Do you get any benefits in getting that much soreness, I couldn’t tell you, some claim that it does, but I doubt it.
        Personally concentric part of the exercise I lift as powerfully as I can (without compromising the form), and the eccentric part is controlled, but not slow.

        1. Sam

          @Zagor, ‘slow’ is subjective…😉

          Something along the lines of 2-1-3 (sec. con-pau-ecc) seems fine for hypertrophy imo.

  2. dan

    Because Charles Glass said so…

    1. TheFinisher

      Because it works. Period.

      1. Sam

        Hahaha, what is optimal for hardly anyone (natural) works surprisingly for the big Finisher … 😂

        1. TheFinisher

          Yeah that’s why natural bodybuilders do it…. You clearly have no idea about bodybuilding, back to your low volume dogshit,

  3. mattsk1

    I can atest that time under tension does effect hypertrophy even with natties. I don’t do slow reps, slow negatives or partials. I do loaded carries. It has added some thickness to my back, shoulders, upper traps, forearms and core. My body weight started to go up to from 170lb to 180lb after switching from conventinal lifting to nearly all loaded carries. I don’t mind sharing my routine to those who are interested.

    1. Kristian

      Can you shared it bro.Appreciate

  4. mattsk1

    I train loaded carries three times a week. I have an A day which is Farmer Carries. My B I call Man Makers. My Man Maker consisit of me lifting a loaded barbell off the floor using snatch overhand grip, walking it 25m, lowering it, then powercleaning it, then strict press, then walk back to the start with the bar in the position front load like front squats, then I lower to the bar to the ground, rest and repeat. I alternate between double overhand and double underhand grip for my snatch carries. I use 135lb for the Man Makers. I do about 4-8 of these in a session depending on how I am feeling. I use 110lb in each hand for farmer walks. I do Front squats each time before I do farmer walks. Thats it. Nothing else.

    1. David

      Love farmer walks! Have you tried Zercher holds and bear hugs?

  5. mattsk1

    Not yet with the Zercher holds and bear hugs. I have my set up at my house and back yard. I can make a bag for bear hugs. I would have to learn out do a zercher deadlift to do the zercher hold walk outside. I do like my snatch grip walks and rack walks. Rack walks are as close to bag hugs I do since it restricts my breathing with the bar bracing my neck.

  6. mattsk1


    You sound like a critic of loaded carries due to infomation. My suggestion is for you to give it a trial run of three weeks and see what it does for you. It is not one size fits all because everyone has different body types, but it is what human kind has been doing for thousands of years unlike all those seated weight machines. At the very least it will strengthen your grip.

    1. Sam

      No, I am not critical, and if it is functional because you have to carry heavy shopping bags, for example, then definitely continue to do so. But otherwise there are smarter exercises for the various muscle groups with more benefits (if hypertrophy is the goal). Did you watch Brignole’s video? Then you know what I mean.

  7. mattsk1

    I see your point now. Yes their are other exersises for hypertorphy. My point is loaded carries can help with that too even if it is not optimal. It can be used as a tool to use but not rely on for hypertrophy for those who are bodybuilding. I am not a bodybuilder so I am ok with my results with loaded carries.

  8. Sam

    Glad we agree! 💪🏽👍🏽

  9. JIM

    In short:

    Just do your own thing. Progress as far as you can naturally. Do what ever you want…train often but do not over train.
    Focus on health not on lifting weights.
    Your diet is 80%+ of the problem/solution
    Genes and body structure is the rest.

    Roiders can by pass all this. Except the health part (and IMHO they do not look good)

    1. Sam

      @Jim, I agree with many of your points, but “80% nutrition” is absolutely incorrect imo. Unless a low body fat percentage is important, nutrition / training is fifty / fifty. Otherwise, training is much more important than nutrition.

      Honestly, I have to say that I have long thought that nutrition is very important, after 40 years of dedicated training, I am aware that this is not true.

  10. Baron2Duke


    I’ve been orbiting at about 165 lbs on regular, IBM of 22.5 for a few years now. My calorie intake is ‘only’ 1600-1800 kcal, with a visible twopack and during summer a fourpack, 2-3 square meals per day, eating everything, no special diet and supplements.

    ‘Science’ would say I am being malnourished, but I feel much better than when over-ate it with 2000+ calories. Not to mention I got lard on my gut when undertook a muscle-mass program few years ago combined with a mass gainer and whey, and got no special size in my arms during those few months. People have different needs for calorie intake even at similar body types, and our own bodies with themselves adjust to it over time.

  11. Sirloin

    The summary of the article is spot on.

    Bodybuilding aside, i suffered a stroke at the age of 24 (now 42), during my recovery i utilized partial reps and static holds with good effect. Ive also found limiting ROM (but still an “effective” ROM) and static holds in different positions of certain exercises have helped with working around various injuries (for me thats a shoulder impingement and 3 herniated discs in my low back).

    Good health and training to all

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