One of the most popular strength sports is Powerlifting, yet, lifters who compete in this sport are not concerned with power, but total force production. Despite this, we often here strength training being called power training or force development being used interchangeably with power development. What is the difference between strength and power in training for human performance?
What is Strength?
As revealed in the StrengthMinde article what is strength training, training for strength concerns any training that is done to increase the absolute force production of the muscles, as expressed by the lifting or moving of heavy external loads, most typically a loaded barbell. The goal of this type of resistance training is to increase your one rep maximum or the maximum amount of weight you can lift. While different rep ranges and parameters will be used at different times to achieve this goal, in strength training, an increase in the maximum force potential of the muscles is always desired. You can read more about force here. While power relates to force production, power development and force development are not the same things.
What is Power?
Power is the rate of doing work or the product of force and velocity (find out more about velocity). So, Power = Force X speed of force application (P = F X v). It can also be described as work divided by time or P = W/t. These two equations produce the same result.
As a muscle’s velocity of contraction increases, its maximum force output decreases. Therefore, a muscle that is contracting slowly can produce more force than a muscle contracting quickly. However, this high force does not also mean high power output. If the muscle’s force output is multiplied by its velocity of contraction, the muscle’s power output for that velocity can be determined.
The maximum power output of a muscle is generally at one-half of the maximum contraction velocity. The duration of an activity produces the power output that an athlete can sustain, making it a constraint that must be considered in human performance.
How is Power Improved?
Power can be improved by two methods: 1) by increasing the amount of force one can produce or 2) by increasing the speed of movement. Strength Power focuses on improving the muscle’s ability to produce force. This is used in preparation for most sports. The ability to produce very high levels of force at a high rate is a key determining factor in sport, and must not be neglected. Compensatory acceleration should always be used during the concentric portion regardless of bar speed. The intent to move the implement as fast as possible is a key determinant in power development. This applies to all training methods. POWER implies using intensities in which there is a more or less equal contribution from acceleration and strength (practically pounds of force against the implement).
As mentioned, the term power is sometimes used interchangeable with strength or displays of high force application but this is not technically correct. Olympic weightlifters produce much higher power than Powerlifters, who produce more force.
Note that a capital P is always used to denote power because a lower-case p is the symbol for momentum.
See also Fundamentals of Biomechanics by Duane V. Knudson, for further information.