Why Do Slow Repetitions?

Yesterday someone in a Facebook exercise group posted a video of himself performing the leg press and asked for comments. Like most of the people who post exercise videos in that group his form needed work. He was was holding his breath, moving too fast, locking out, stopping to rest at the end point, bouncing at the bottom, allowing his pelvis to lift and tilt/spine to flex, and appeared to be gripping the handles hard and forcefully extending his neck against the seat pad.

Understanding of and standards for exercise form in this group aren’t very high, and a few people commented that his form looked “good” or even “perfect”. Normally I don’t reply to posts in the group. I only follow groups like this because reading the discussions and watching the videos is a good way to find popular myths and misconceptions to address in articles. However, he was an older trainee and if he continues to train like that or follows some of the other advice he was getting he is likely to injure himself, so I offered some advice anyway. Trying not to be too harsh I wrote,

“Good effort, but need to work on form. Slow way down. Smoothly reverse about ten degrees short of lockout without stopping to rest there. Don’t hold your breath. Reverse direction more smoothly at the start. Worry less about how much weight you lift and more about how well you lift it.”

Within seconds someone was disagreeing with me, claiming that slowing down during the negative would “hamper building up overload” and be harder to recover from. It was almost time for dinner and I didn’t feel like explaining and told him so, but he said he was interested in learning so I wrote the following brief explanation. I’m sharing it here (with minor editing for grammar and readability) in case others find it helpful:

“Cool. First, it’s important to understand where I coming from. When I train people I have three rules:

The first is to make sure their program is based on their body, goals, and circumstances and not cookie-cutter. The general principles are the same for everyone but the best application varies between individuals based on these.

The second is not to hurt anyone. If there are different equally effective ways to accomplish the same goal always choose the one with the lowest risk of acute or overuse injuries.

Third is don’t waste their time. If there are different equally safe and effective ways to achieve the same goal, choose the most time efficient.

Consider that mechanical work and power during exercise isn’t very important. It’s not how much work you do that matters, or even the absolute force produced in most cases, but the relative effort.

Tension and metabolic stress matter. How many times the weight goes up and down doesn’t. You can hold a weight motionless, or move it up and down really fast, or something in between and stimulate comparable improvements in muscular strength and size over time, but moving more slowly allows you to reduce acceleration during the turnarounds avoiding potentially harmful increases in force and allowing better control over the movement. If you are training hard you can get decent results with a variety of speeds, but slower is generally safer.

Avoiding lockout increases the difficulty of the exercise so less weight is required to produce the same level of fatigue in the same time frame. Imagine performing squats in only the bottom half of the ROM with no bounce at the bottom, no rest at the top. It makes it much harder so the weight has to be reduced, meaning just as effective but less compression on the spine.

Contrary to what many believe, you don’t need to move fast during exercise to recruit the fast twitch motor units. Recruitment depends upon force requirements and fatigue, and even with moderate loads eventually all of the motor units – even the fast twitch ones – will be recruited even at slower speeds, even with isometrics which is as slow as you can get.

Power production in other movements improves as muscular strength increases regardless of the speed the strength is built at. Specific skill training for a particular athletic or vocational movement is a separate thing, and that is where movement specific speed is important. Since there is no general physical advantage to moving more quickly, and since moving slowly reduces the risk of injury, I have people move more slowly.

In a much, much broader sense, any reasonable strength training program – anything done hard, progressively, and consistently with a volume and frequency appropriate to the individual, will eventually get someone as strong and well conditioned as they are capable of. Lots of things work. However, not all of them are as efficient or safe.

Over a long enough period of time if you compare the potential results of different training methods the difference becomes zero since it is ultimately dictated by individual genetics. In the long run, as long as the programming is suitable for the individual and the volume and frequency don’t exceed what they can recover from and adapt to, they all work. However, the longer you do one program versus another, the larger the differences in time investment and risk become. What might be a small difference in weekly time invested, wear on the joints, and risk of injury becomes cumulatively larger as months and years pass. So, in the long run although there is no significant difference in potential results the difference in time invested and risk continues to grow.

Going slower doesn’t just make exercise safer though, it can also make it much harder thus more effective, especially if you move more slowly in those portions of the ROM that are more difficult that most people tend to rush through. Keep in mind the goal during exercise is not to do something to the weights with your muscles, it is to do something to your muscles with the weights. How much you lift, how many times, etc. doesn’t matter. How efficiently you create tension and fatigue in the target muscles matters.

Consider those guys at the gym who only do quarter squats or leg presses because they are focused on weight while ignoring resistance (weight x lever, mostly). It’s the same thing taken much further. Going the opposite direction, if you want to make the exercise as difficult as possible you should avoid positions in an exercise where there is little or no meaningful resistance, not spend much time where there is only moderate resistance, and take your time where there is a lot, because the goal isn’t to make the weight go up and down, it is to use the weight to challenge the muscles you’re working as much as possible, as safely as possible.

One of the most important things to understand about this, and one that almost everybody gets wrong, is that it is about resistance, not weight. Too many people are too concerned with how much they can lift rather than how well they lift, how efficiently they create resistance against the target muscles with a given weight. Unless you are a competitive lifter, and even then it only matters for the competitive lifts, your goal during an exercise isn’t to lift as much weight as possible, it is to create as much demand in the targeted muscles as possible.

This can be done more safely and efficiently with less weight when you move in a way that increases rather than decreases the average lever against the targeted muscles. Often, when a person’s form sucks it is because they’re focusing on how much weight they can move instead of how well they’re able to move it. Slowing down improves your ability to feel and focus on the tension in the target muscles and to be able to adjust your positioning and movement based on that feeling, to keep the tension high.”

I then ended with a quote from Fisher J, Steele J, Bruce-Low S, Smith D. Evidence Based Resistance Training Recommendations. Medicine Sportiva Med Sport 01/2011; 15:147-162 which you can read about in my Evidence-Based Resistance Training Recommendations posts,

“Comprehensive reviews of this area of research have reported that resistance training at shorter repetition durations produced no greater strength or power increases than training at longer repetition durations [18, 129]. The latter study also considered the application of Olympic lifting and plyometric exercises concluding that there is no evidence to suggest that these techniques can enhance strength and/or sporting performance (including vertical jump and sprint) to any greater degree than traditional weight training methods.Also,Bruce-Low and Smith[129] specifically considered the risk of injury from ballistic exercises, reporting some disturbing statistics suggesting that explosive lifting such as that involved in performing the Olympic lifts can cause injuries to the wrist, shoulder, elbow and lumbar region.”

This morning there were a few replies, and while the original poster thanked me for the feedback (and I hope he applies it – his knees, hips, and spine will thank him) the commenter was incredulous. After expressing several misinformed opinions about mechanical work and exercise, volume, frequency, etc. he asked,

“Are you seriously talking about 5/5 and 10/10 cadences on your blog or are you just using these humongous numbers as examples?”

When I told him I was serious, he dismissed me entirely, saying he wouldn’t touch the subject “with a ten foot pole”. Considering how people accept without question all sorts of utterly ridiculous things from the fitness and bodybuilding media it’s odd some are so skeptical about moving slowly during exercise. I wasn’t going to waste any more time on it so I told him if he wanted to learn more in the future I’m easy to find. In closing I wrote,

“Just keep in mind what I said about the long term; any method of strength training done hard, progressively, and consistently with appropriate volume and frequency for the individual will eventually produce the same general physical improvements, but in the long run they’re not equally safe and time efficient. I value my long term joint health and mobility and I value my time. Anyone who does owes it to themselves to at least “empty their cup” and learn about safer and more time efficient alternatives.”

Will the original poster take my advice and improve his form? I hope so. Will anyone else who reads my comments do the same? I hope so, but I’m not optimistic considering the overwhelming amount of contradictory and misinformed advice given by other members of the group. I’d like to be able to help everyone, but consider something I recently told a reader who was frustrated that someone ignored his advice against overtraining:

“Keep in mind almost everybody else is telling him the opposite, that more is better. It isn’t enough to tell someone they need to do less, you need to explain why. Even if you explain it effectively he may not change for various reasons. He might not believe you because of blind faith in the bodybuilding media. His ego might be too invested in what he’s doing. He may have other, non-physical reasons for wanting to exercise more frequently.

Maybe he will give it a try eventually when he accepts what he’s doing isn’t working. Maybe not. You definitely can’t help everyone, but don’t let the ones you can’t help discourage you from continuing to try to help others.”