Wednesday, April 16, 2008

Work Capacity

We all may have slightly different fitness goals, but no one is going to argue that they don't want to be in 'better shape.' The only problem with being in 'better shape' is that it is very vague. What does this mean? How do you know if you are in better shape? Do you weigh less or more? Are you stronger or in better aerobic condition? What about your physical health? Your energy level?

After training for years, my answer is.... being in shape = better work capacity. What is work capacity? First, we have to review some basic physics to answer this. Then we can easily see how it is applied to fitness. Work, in physic's terms, equals force times distance. Think of force as moving a mass (i.e. bodyweight or kettlebell). The greater distance we move a force the more work and energy it takes (think of climbing a flight of stairs, the more stairs, the higher we go the more work is done). So, the greater work capacity we have, the more work (moving a mass over a distance)we can do without fatiguing and risking injury.

Lets apply this to exercise training and fitness. If I do 10 pull-ups with my body weight (215 lbs) I have moved a mass (215 lbs) a distance (shoulder to wrist, say 24") times 10. This equals 215 lbs x 2' x 10 = 4300 foot-lbs. Sounds impressive! However, how long did this take me to do? One minute? Thirty minutes? Six hours? The time it takes you to perform this work makes a difference. So, we need to divide our 'work' by the time it took to complete the work (4300/ time). Now we have our work capacity defined as work/time. The beauty of this, as measure of fitness, is that it is dependent on our strength, endurance, and body composition. So if we improve any or all of these facets of fitness we will improve our work capacity. If we are lacking one facet (low strength level and push-ups) then that will negatively impact our work capacity.

For these reasons, I have been incorporating more timed sets. We can objectively see if you are getting in better shape by the number of repetitions performed in a period of time. Also, this is a great motivator. Tell someone, after performing 39 challenging reps that they need three more reps, with only 0:12 seconds left in their set, and watch them push themselves 100% to get those last three reps.

Speaking of work capacity, congratulations to Ray for performing 62 kettlebell snatches with a 26lb kettlebell in 3:00. Not bad for a 57 year old guy!

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