Strength Versus Power (Part 2 of 4)

By Vince Del Monte, WBFF Pro Fitness Model, Certified Fitness Trainer and Nutritionist and author of No Nonsense Muscle Building.

Strength is of primary importance regardless of the goal and today we’ll compare the role of strength in power development, and vice versa.

The nuts and bolts of what you must understand…

  • ‘Power’ is measured by this equation: force X distance / time
  • The ‘force’ variable is limited by how strong you are – therefore, you’re ability to express and develop power is heightened in direct proportion to your ability to generate force (which is a reflection of your strength)
  • The ability to express power is a collaborated effort of the nervous system and muscular system – the more coordinated their effort, the greater power expression, and increasing the capacity to express power can indirectly increase your capacity to stimulate growth as a result of the increased capacity to recruit the largest, strongest muscle fibers

In the first part of this miniseries I built a case about the importance of being strong in a relatively vague way. In Parts 2, 3, and 4, I’m going to compare strength to other physical characteristics to help further cement the point that strength, up to a point, is of primary importance regardless of the goal. So let’s compare the role of strength in power development, and vice versa.

Power can be defined as the ability to generate maximum force in minimal time – in fact, the equation for ‘power’ is: force X distance/time (force times distance, divided by time). In this case the ‘force’ is measured in terms of the amount of weight on the bar – therefore, by this definition, the faster a given load travels from one point to another, the greater expression of ‘power.’

But Who Needs Power Anyway?

Well, based on the components of the equation, anyone who relies on their ability to move from one point to another, in as short a time as possible, needs to be powerful. Since power is a reflection of the rate in which one can produce a substantial amount of force – also termed the ‘rate of force development,’ those who need to be able to accelerate, or create momentum, also need to be powerful.

What about those who want to build muscle? Well, they benefit from being powerful as the ability to demonstrate power is dependent on motor unit activation, which is the result of the coordinated effort between the nervous system and the muscular system. The more motor units that are recruited and the faster they are recruited, the greater force production potential there is, and this is developed in direct proportion to increasing power. Since muscular development is also dependent on motor unit activation/stimulation (if a motor unit is not recruited, it is not trained), increasing power can increase the capacity to stimulate growth.

Even those who are training to reduce their body fat can benefit from the type of training geared toward increasing power, as explosive efforts have the most positive downstream effects on insulin sensitivity. Basically, the types of explosive lifting included in the training geared towards increasing power promotes the body to send more nutrients to muscle tissue and less to fat cells! If the fat cells are more sensitive to insulin, for the same amount of caloric consumption, you’ll gain more fat and less muscle – so, obviously for someone training for fat loss, the goal is to tip the scale in favor of muscle insulin sensitivity as much as possible, and explosive lifting will do that better than any other kind of lifting.

 

Here’s an example for using explosive strength training to build muscle and lose fat:

 

Understanding Power, And The Role Of Strength In Power Development
To better understand power, and the role strength has in power development, let’s break down the power equation above into its simplest terms:

Force: measured in terms of how much weight is on the bar – this will vary depending on the load selected in relation to the individual’s strength levels.

Distance: measured in terms of how far the bar travels in relation to the beginning and end range of motion – this variable is ‘fixed’ and remains constant.

Time: measured in seconds, or milliseconds, starting and ending in direct proportion to the range of motion of the lift – this will also vary depending on the load selected in relation to the individual’s strength levels.

Since we can’t practically measure how much force is being applied – all we know is the force must be greater than the amount of weight on the bar in order for it to be lifted in the first place, we measure it in terms of how much weight is on the bar. We then use the distance in which the bar travels and divide it by the length of time in which it travels to come to a conclusion of how many units of power were produced.

Using this equation, we can conclude that there are two ways in which an increase in power can be expressed:

  • Lifting the same amount of weight in less time
  • Lifting a greater amount of weight in the same amount of time

 

Linking Strength Development To Power Development

Let’s use a hypothetical example to link the development of strength to the development of power, and how increasing strength can increase the capacity to increase power.

Generally, when training to develop power, you want to select a load that allows for the heaviest load to be used without negatively compromising the amount of time it takes to complete the lift – since these are the two variables that can fluctuate.

The heavier the weight is, the slower it will be lifted, and the longer it will take to travel regardless of the distance between the beginning of the range of motion and the end.

The lighter the weight is, the faster it can be lifted, and the less time it can take to travel the same distance. There is a point however where the tradeoff in reducing the weight simply doesn’t allow for the weight to be lifted any faster. For example:

Let’s pick an exercise with a relatively long range of motion – since the range of motion is constant (as long as form/technique remain consistent). We’ll use a deadlift, since the range cannot necessarily be varied from rep to rep, and compensation due to fatigue or weakness won’t alter the length of the movement.

deadlift

 

The length from where the bar rests on the floor to where it rests at the top of the movement will be nearly identical every single time. With a squat or bench press, it’s possible to manipulate your body to alter the range of motion a lot more than a deadlift in which the bar starts on the floor, and is held at arm’s length in an upright position upon completion of the lift.

Let’s also say that the range of motion between where the bar rests on the floor and arm’s length in an upright position is two feet.

Let’s use a hypothetical max of 405 lbs, and hypothetically compare the effect that 90%, 80%, 70%, 60%, and 50%, has on power expression.

If 405 = 100% of what can be lifted:

  • 90% = 364.5 lbs
  • 80% = 324 lbs
  • 70% = 283.5 lbs
  • 60% = 243 lbs
  • 50% = 202.5 lbs

Now, let’s say that a true one-rep max for a lift that covers a broad range of motion like the deadlift, will take three seconds to complete. If we plug these numbers into the equation we get:

F = 405 X D = 2 feet / T = 3 seconds

  • 405 x 2 = 810
  • 810 / 3 = 270

Therefore, a one rep max with 405 lbs yields 270 units of power.

It’s important to note that power is an arbitrary term used for illustrative purposes in this context. By no means do these numbers reflect exactly how long it would take someone with a 405 lb. max deadlift through a full range of motion, assuming their full range was exactly two feet. This is strictly for demonstration purposes.

Moving on, let’s say that a 10% reduction in weight results in a one second reduction in time. If we plug these numbers into the equation we get:

F = 364.5 X D = 2 feet / T = 2 seconds

  • 5 X 2 / 2
  • 729 / 2 = 364.5

In this case, one rep yields 364.5 units of power.

Let’s continue on, but I’m going to skip a few steps by removing the equations (since you now have an idea of how they go), and simply provide the answers:

  • 80% yields 648 units of power, assuming that it takes roughly one second to lift through a full range of motion.
  • 70% yields 667 units of power, assuming that it takes roughly 0.85 seconds to lift through a full range of motion.
  • 60% yields 694 units of power, assuming that it takes roughly 0.7 seconds to lift through a full range of motion.
  • 50% yields 810 units of power, assuming that it takes roughly 0.5 seconds to lift through a full range of motion.

If we continue on with reducing the weight to 40% and then 30%, and so on, what happens is that the units of power would begin to decline because at some point it’s simply not possible to lift any faster. Remember, to develop power, the ideal load is that which is the heaviest load you can handle without negatively compromising the amount of time it takes to complete the lift. Since you can only lift so fast, anything lower than what you can lift with maximal speed will result in less power being expressed. For argument’s sake, here’s what 40% would look like (under the impression that the speed in which a full range lift is capped at roughly 0.5 seconds):

  • 40% = 162 lbs

162 X 2 / 0.5 = 648 units of power – which happens to be the exact same in this case as 80%. Therefore, in this example, and in this example ONLY, it would suggest that the loads best suited for developing power are anywhere between 50% and 80%.

So how does strength tie into this whole thing? Well, think about it – in the hypothetical example above, we used 405 lbs as our max. And in our example we concluded that the best loads for developing power were between the 50-80% range, which in this case would be 202.5-324 lbs. But what if the individual in question needed more power for some reason? Since using loads below 50%, or above 80% in this case will not yield the greatest response in terms of expressing power, what options would there be?

Well, let’s take a moment to think about what would happen if the individual increased their deadlift by 100 lbs. Would doing so lend itself to an increased capacity to develop power? Of course it would, because if we are limited to the 50-80% range of our max, increasing our max would mean that the loads that fall under the 50-80% are greater! And this is how strength can be a limiting factor in terms of power development, because the more you can lift, the greater the loads you can use that fit within the range best suited for increasing power.

If we add 100 lbs to our hypothetical example we end up with a 505 lb deadlift, and a range between 252.5-404 lbs. In this case, what was once a max effort lift, is now within the range to develop power. And just how much more power can we express with these loads? Well, 50% now yields 1,010 units of power – an increase of 200 units of power, and 80% now yields 808 units of power – an increase of 160 units of power (this operating under the assumption that it takes the same amount of time to lift the same relative amount of weight: basically this assumption suggests that it takes roughly one second to lift 80% through a full range of motion in the example above, regardless of how much 80% actually is).

At the end of the day, those training for increased power can become limited by the strength levels, and by increasing their strength levels, they increase their capacity to further develop power. When viewed through this scope, it’s easy to understand how strength serves as the foundation upon which power can be built.

 

What’s your take on power? Have anything else to share?
Let me know in the comments below!

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Like this article? Check out the rest of the series at the links below!

Strength: The Common Denominator Irrespective of Your Ultimate Goal (Part 1 of 4)

Strength Verses Endurance (Part 3 of 4)

Strength Verses Size (Part 4 of 4)

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