We hosted a seminar this past weekend at Squats & Science Bushwick. We had a great time, and on my flight home as I was reminiscing on the event, I realized I wasn't fully satisfied with an answer I gave to what I thought was a simple question: why is a shorter range of motion (ROM) better than a longer ROM?

The first answer I gave was about the definition of Work.

W = F*d

Where F is the force you're exerting on the bar, and d is the displacement or ROM. 

As you reduce ROM, you also reduce Work, which is in Joules (a unit of energy). You can convert from 1 kcal to 4.184 joules, so you literally burn less energy with lower ROM. But, that still doesn't quite explain why lower ROM is better.

It kept nagging at me, and my plane didn’t have screens, so I came up with something I'm more satisfied with. 

The sport of Powerlifting is essentially an optimization algorithm for one very specific skill, the ability to output maximal force for the longest possible amount of time. 

A beginner, when attempting a one repetition maximum (1RM), will likely hit a brick wall when there's a slight pause in the lift, and then the bar collapses back down. That point, the 'highest' point of the lift where they briefly paused, is also the point where they're applying maximal force. They are only able to apply that force for a brief period, so the lift often fails. 

An advanced athlete, however, still encounters maximal effort reps where the bar slows significantly or even stops moving (the moment of maximal force output), but they're able to exert that maximal force for much longer, often making it through the lift to completion. 

The effect is an eventual 'training down' of the average concentric velocity (ACV) of the lift. The ACV being the distance traveled over the time it took to complete the lift. Distance over time, where distance is in the numerator and time is in the denominator. 

In fact, recent research shows this to be the case. A lifters velocity at 1RM is highly correlated with their training age, or the number of years (or months) the lifter has been consistently training. So the goal becomes clear, how do I get better at training down my velocity at 1RM (V1RM)? Well, there are two ways - you can reduce the numerator, or you can increase the denominator.

Your arms don't get shorter over the course of your lifting career, so it would make sense to focus on the denominator. If you can apply maximal force for a longer period of time, that bench press takes longer, thus increasing the denominator of the equation and lowering your ACV. This is different from simply slowing down your rep. Yes, that will also increase the denominator and lower ACV, but you’re no longer outputting maximal force. This is why maximal intent for speed it also critical in the sport of powerlifting (more on that in a future blog post).

But, what if instead of shortening your arms, we can shorten your ROM? This is possible by retracting shoulder blades, widening grip, and arching your back. The result is the same. Your V1RM goes down. 

Intuitively, it makes sense that you can either get better at exerting maximal force over a longer period of time, or you can reduce the amount of time you need to exert maximal force (by reducing ROM). 

Hopefully this helps you wrap your head around what turned out to be a very interesting question.