After reading some of the interesting comments some of you had written in one of my previous posts I’m kind of forced to explain the physics after that. I´ll do my best to do it in the most understandable way. Don’t hesitate asking for any help of clarification here or by private if needed.

Whenever we lift weights, we are exerting force against the barbell. In physics, they measure force using Newton’s Second Law of Motion via the equation F = ma, or putting it in a different way: force is equal to mass multiplied by acceleration. So, basically, to generate more force, we must either increase mass or acceleration (or both).

As we all have noticed when working out, heavier weight moves slower; lighter weight moves faster, in a more explosive movement. We are always moving faster 80% of our one-rep max weight than the 100% one. No doubt about it. Stating it in a different way: lighter weights will lead to higher acceleration.

Strength training is a function of the second law of physics. Moving a heavy mass with minimal acceleration will produce one type of strength. Rapidly accelerating a lighter mass generates a significant amount of power.

Now, linking the previous post I wrote, we may need to put our muscles under tension for around 40 seconds (average) for the muscular laceration start. If you are using high weight with low repetition will you be able to reach to those 40 seconds or will it be easier to do so when using lighter weights (60-80% of your maximum) and high amount of repetitions?

According to science, the most efficient working out will be the lighter weights one, with high acceleration (explosive concentric movements and controlled eccentric ones) during certain amount of time (not repetitions) –40 seconds–.

So, basically, lifters generate more force at 60% – 80% of their one-rep max than they do above or below those levels basically because they can move them faster and they can be more time moving them before failure.

We should use science to train better and to improve our physical condition while minimise the risk to be injured. Think in terms of fast or slow, not heavy or light!