One of the things that drives me crazy is the misinterpretation of research results. I have most often seen this in the case of measuring physics outputs like force, impulse, or power. I have previously posted and ranted on this topic regarding regarding sprinting research.

The key to Bolt’s success

Ground reaction force in sprinting


Here are some more examples.

What load maximizes power production in jump squats? Much research has been done on this topic, and a variety of loads have been identified as optimum.

jump squats

This inconsistency in the conclusions comes from variation in the research methods and in the research subjects. Is body weight included in the 1RM and the testing loads? Are the jump squats done with a free barbell or on a smith machine? What are the instructions given to the research subject? How was the movement executed? How strong were the research subjects? These are all factors that influence the results of the research. In spite of all the variation in conclusions, people have still tried to sort through all the data and come up with a load recommendation for peak power, such as 30% of 1RM squat or 40% of total system weight. I do not have any interest in getting in on that discussion. My message is that NONE OF THIS MATTERS. Which load evokes the highest power output is irrelevant.

Why? Isn’t increasing power critical to improving athletic performance? Yes, absolutely. But the load that evokes the highest power output immediately is unrelated to the load that will produce the most powerful athlete over time. The goal is not to win a contest of who can get the highest force plate reading. The goal is to make an athlete generally more forceful in sporting movements. To do this we develop strength and explosiveness. Power is just an arbitrary physics measurement, and trying to optimize it on jump squats is a completely meaningless pursuit.  We need to stimulate adaptation by the body, not manipulate the load on a particular exercise to produce the highest power output right now.

Let’s say we could identify the best load for power. But then we also say that athletes need to improve force production, so we find the load that produces the highest force. But then we also say athletes need to improve acceleration, so we find the best load for that. See where this is going? Which of these “ideal” loads is the correct “ideal” load? None of them. They are all completely arbitrary.

“Which load produces the highest X, Y, Z?” is the wrong question to be asking. Instead ask, “What stimulus am I trying to get out of this exercise?” For sprinting and jumping athletes, jump squats are a strength exercise. Yes, they are explosive. But if you want to train explosiveness for sports, you shouldn’t be slowing yourself down with weight on your back. So jump squats are a strength exercise. Depending on the athlete and the situation, jump squats may be used to build strength, to maintain strength, or to measure force or power.  If you’re measuring something, pick a weight and stick with it over time. It should not really matter what that weight is. If you are training strength, and you want a stronger stimulus from jump squats, use more weight and/or drop down lower in the counter-movement. If you want less of a strength stimulus, use less weight and less knee bend. It’s that simple.

So let’s say I’m training a sprinter. In the off-season we’re working on strength, but I want to have a consistent measure of power along the way. I might choose jump squats on a force plate for that and use a load of just 40kg with minimal knee bend to keep it fast. Then the season comes around, and we stop using heavy lifting but want to maintain power. Maybe then we keep testing with 40kg, but do some jump squats with 70kg and some more knee bend to get more of a strength stimulus. Then let’s say the sprinter has a minor injury and can’t train for a few weeks. When he comes back, we want to get some strength back quickly but not slow him down with heavy deep squats. So we do some jump squats with 100kg and 2/3 squat depth to get an even greater strength stimulus. Adjustments are made based on the stimulus we want from the exercise. At no point in that process is the load that maximizes power relevant.


Straight bar deadlift vs hex bar deadlift.

The increasingly wide spread use of hex bar deadlift has sparked a fair amount of debate on whether or not it is superior to straight bar deadlift. Research done comparing the two versions has shown consistent results. The hex bar involves more knee loading and less hip loading and as a result uses the quads more and uses the posterior chain less than the straight bar deadlift. Lifters also tend to push greater force and power into the ground in hex bar deadlift. This leads some people to conclude that hex bar is the superior deadlift for athletic development.

My response again is that these force and power numbers do not matter. Getting high ground reaction forces is not the purpose of deadlift. You could do tuck jumps on a force plate and produce far greater force and power than any version of deadlift. Does that mean tuck jumps are a better exercise for athletes? No, they’re just different. All strength exercises involve relatively low ground reaction forces, because we train strength by getting into biomechanically weak positions and lifting out of them. In weak positions we produce a lot of muscle tension but not a lot of force into the ground. In the case of deadlift, the hex bar puts the body in a slightly stronger position, so the forces tend to be a little higher, but that is not a meaningful difference. The purpose of a strength exercise is high muscle tension and high neural drive, not high ground reaction force. Now if you perform the exact same movement with the exact same load and produce greater force or power than before, that is an indication of increased ability. That is meaningful. But one movement producing different physics outputs than another movement is irrelevant.

Again the correct question to ask is, “What is the stimulus on the body?” In the case of hex bar and straight bar deadlift, both are concentric lifts from the floor. Both use knee and hip extension, but hex bar is slightly less hip dominant. So if you want to be more hip dominant, use straight bar deadlift. If not, use hex bar. It’s that simple.