Should You Train for Power?The goal for every training session is to facilitate physical adaptive responses, like increases in muscle size and contractile capacity. We know that, all else equal, an improvement in your ability to produce power is a useful, salutary improvement. The question is, how do you become more powerful?
Become Positively Powerful
More and more, coaches and athletes are becoming obsessed with power output. Whereas cyclists have revered the wattage calculators on their bikes for ages, runners are now putting devices in their shoes to measure the power output of every foot strike, and you can buy devices to attach to your barbell that will calculate the power output of every rep. The trend is toward power as both the guiding metric for training and the predictor of performance in endurance sports, and one can make convincing arguments that as the technology becomes more widespread, strength training will revolve around power output as well. Power is a neutral physical measure, subjective only to the individual. With enough data, you can, theoretically, prescribe training stress based on power output rather than performance metrics. This means that power production may be a more accurate metric than physical displays (such as your performance in the main barbell lifts).
If that’s the case, then why doesn’t everyone train for power rather than just strength? To answer that, we need to take a closer look at power, what makes a person more powerful, and how we can train for power production.
What is Power?
“Power” describes your potential to generate or transfer energy to the world around you through the use of force. Force is the fundamental quantity that produces movement in our physical space. Like distance, time, or space, it describes a concept that we understand intuitively and have developed standardized systems to measure. Whereas force is the thing that tends to cause movement, power describes the quantity of energy supplied in the application of force. If we analogize to other familiar quantities: distance (like force) is a static quantity—one mile is one mile because we say so—speed (like power) measures distance with regard to time—e.g., miles per hour. Power is an in-the-moment snapshot of energy transfer over time. To understand what that looks like, let’s first remove the time component.
We can describe the transfer of energy that causes, or allows for, movement, with two basic concepts: force and distance. When a force causes movement or displacement of the point of force application in the direction of the force, we call that work. The existence of force is the description of the potential for movement in our physical space, and we can describe or measure actual movement by its work. Things that can create or direct force have the capacity to do work; when movement occurs (work is completed), we can measure the amount of work accomplished in the system. For a comparison between work and power, think of it this way: the concept of work is backward-looking (how much work was done); the concept of power is in the moment (how much work is being done right now, or when the measurement was taken).
The nature of power also means that it is predictive of both energy output and outcomes. Going back to our distance/speed analogy, for a journey over a set distance, you can predict both how long that journey will take and how much fuel you will burn at any given moment by your speed and with sufficient data about your vehicle’s efficiency. A car traveling 10 miles an hour will complete the journey, but a car that is traveling 100MPH is going to do so much more quickly.
Human energy output is measured in watts. A watt is the amount of work performed at the rate of one joule per second. As we know, work is force and distance. The joule is the standardized measure of work—a force of one newton acting through a distance of one meter. Knowing the average power output for a period of time, you can predict a person’s energy expenditure. 400 watts, sustained over one hour, would require 1,440,000 joules, which would be 344 kCal expended over the hour. (This would be an extremely high amount of sustained power output.)
Cyclists have harnessed the measurement of power for training and performance. The bicycles used at the highest levels are around 95% efficient, meaning that most of the force the cyclist generates goes into turning the crank and moving the wheels. With a relatively simple device, cyclists can measure how much power they put into every pedal stroke. With loads of training data, they can get a clear picture of what wattage they can sustain and for how long. This is useful because power output from the body to the crank doesn’t change with the terrain. Whether the cyclist is climbing the alps or flying down a hill, 400 watts is 400 watts.
And that is what is really important about power output. It is oblivious to the terrain, your perceived effort, and even (to an extent) the weight on the bar. A watt is a watt. While there are some barbell training utilities that can measure power output and the future of barbell training may very well start to look more like cycling, with prescriptive wattages in addition to prescribed volume and intensity factors, we aren’t recommending you start viewing power output as a goal of your training session. The goal for every training session is to facilitate physical adaptive responses, like increases in muscle size and contractile capacity. Instead, we know that, all else equal, an improvement in your ability to produce power is a useful, salutary improvement. The question is, how do you become more powerful?
Train Strength to Generate Power
The answer, as with so many things in life, is math. Power is work performed quickly. Work (W) is the product of force (F) and distance (d). (W=F*d) On earth, if you want to move a 100kg mass vertically, you would need to exert force in excess of 980N. If you move the mass 1 meter, you will have exerted 980 Joules of work. If it took one second to complete the work, then you would produce 980 watts. For a given task, we may assume that the distance part of the equation is given, whether for a barbell lift, a pedal crank, a foot strike, or a vertical jump. There are two ways, then, that you can increase the amount of power in the movement. The first is by decreasing the amount of time it takes to accomplish the work. For our hypothetical, if we halve the time, the wattage doubles. Imagine the equation as a deadlift: if it takes you second to lift a 100kg barbell one meter, you will produce less power than if you move the bar the same meter in half a second.
The other way to increase power is to increase the amount of force in the equation. It takes a minimum of 980N to move 100kg. If we increase the load on the bar to 200kg, then the force to move the bar vertically will be a minimum of 1960N. If the time and distance stay the same, you will have doubled the wattage for that movement. So, to improve power output, you either have to decrease time (do the same work more quickly) or increase the amount of force (do more work at the same rate).
When it comes to human performance, there is a limit to how quickly you can do anything. That limit is different for everybody. Very explosive athletes are able to produce force extraordinarily quickly, as demonstrated by things like the vertical jump test or throwing abilities. But their ceiling though exponentially higher than most people’s is quickly reached and will not fluctuate much so long as they are in game-day shape. The same could be said of yours and our abilities to produce force quickly. Moreover, a specific task like the vertical jump is different from other powerful athletic movements like the Olympic weightlifting lifts or various throwing events. Power production will depend not just on force and time, but efficiency and skill in those particular movements.
But the ability to produce force is both general and trainable. Force production requires strength, and strength is eminently trainable. The trainability of an adaptation depends on our ability to cause an overload, the specificity with which we can direct that overload toward the desired adaptation, and the reversibility of that adaptation. Neural-motor components that allow you to recruit muscle mass (and produce force) quickly change rapidly and to a small degree with targeted training, tapering off quickly. The same goes for your skill and coordination to produce force in specific ways. There is a narrow range of improvements in both these areas. But a person can increase muscle size and their ability to produce force continuously for years, perhaps even decades, depending on when and how they start.
The takeaway for all of this is that power measurements are useful, and they may become even more useful in the future. However, we have to remember that power is a less general display of physical competence than basic strength. It is built on a foundation of neuromuscular efficiency, skilled and efficient movement, and the general strength that you are building every day in the gym. While the more powerful you become, the more capable you will be, the best way to become more powerful is to improve your ability to produce force—to train for strength.