Sunday, January 25, 2009

Wattage while climbing...


MEN AT WORK. Climbing stairs is definitely "work" but it can also be measured in terms of "power." From a previous post, Power is summarized as how quickly work is being done.

If Work is equal to how much weight is being moved how far (foot-pounds), then power is equal to how much work in a certain time (foot-pounds per second). This Power notation is then converted into the common unit of measurement -- WATTS.

I decided to compare a couple of stair training sessions with regards to Work and Power. Since my race is timed, the time element is important to me! Here are four different stair WOs and my performances:
  • A = 84 floors, 20 carrying 70# of sandbags, all with 25# vest, in 25:26.
  • B = 84 floors, 20 carrying 70# of sandbags, no vest, in 21:48.
  • C = 60 floors, none with sandbags, all with 25# vest, in 17:30.
  • D = 84 floors, 20 carrying 70# of sandbags, all with 50# vest, in 27:50.
As you can see, some are with sandbags, some are while wearing a 25# or 50# weight vest, and two different distances. Each of the four was done on a 4-floor tower, and I had to walk down between climbs...but the timer continued. The time began before the first climb, and ended when I got to the bottom after the last climb. Lastly, I kept my weight to be 238#.

Here are the Work results:
  • A = 279,077 N
  • B = 254,129 N
  • C = 187,461 N
  • D = 304,024 N
Now here are the Power results:
  • A = 183 Watts
  • B = 194 Watts
  • C = 178 Watts
  • D = 182 Watts
These results are worth study time. I don't think anyone needed a physics calculation to determine that the most work was done during workout D...the one with the most weight and the tallest height. Surprisingly, the most Power was produced on the training session WITHOUT the weight vest. The added weight (and added time necessary to complete the WO) did not balance out with the longer duration of the weighted climb. However, during workout B, I still carried sandbags up every 4th climb. I wonder how my Power output will change on 84 floors without any sandbags. I bet it goes up as my time decreases.

My hypothesis is this: In preparing for a timed event such as a stair race, training sessions should focus on Power more than Work Performed. I should be shedding the weight vest for faster upward sprints...attempting to reach (and train in) the highest Power output possible. Maybe I'm totally wrong on this. Maybe practicing with the vest has allowed me to produce more Power without it.

For now, I will be limiting the weighted training sessions until my race on Feb 8th. Then I will have the luxury of messing around with different loads, heights/floors, durations, and whatnot.

Comments? Disputes?

Note: On 02-08-09, I made a few adjustments to this post for consistency sake. It did NOT affect the outcome, only the unit of measurements. LH

Note: On 10-22-09, I adjusted the units to Newtons and Watts using more accurate data of the heights of the climbs. LH

2 comments:

George Demetriou said...

Those are good times Lou!

84 floors is roughly what you would have done to rescue people in the World trade center on 9/11, just fyi.

I agree with doing less weighted work as you approach race day. It's probably better to work with the weight, if any, you'll carry on race day and try to get as fast as possible. Better to train the nervous system for power as you approach race day.

I'm impressed that there is only, roughly, a two and half minute difference between when you wore the 25# vest as compared to the 50# vest.

Thanks for sharing this, the data is interesting!

lisa said...

Hey those are very interesting times...I cant believe all the weight you hauled! That was truly impressive and inspirational. As in the orvious comment mentioned it like going dow nthe stairs during Sept llth. and having to cary someone else. Its developing the CNS too...
I was also very interested in your "female" section post. Its good for both men and women to read tht!
thanks for your contributions, you really put out gret info. I really enjoy your site.
be safe -lisa