View Full Version : Re: Bolt

09-07-2008, 03:02 PM
Hello Colleagues,

I think it's very interesting to estimate Mr. Bolt's power output in the first 4
seconds of the run when he reaches the velocity of ~12.5 m/s shown in
Fig.2. Based on his kinetic energy, he would need to generate ~1450 watts or
2 HP.

If you put his step frequency (~4.0 Hz) with a leg-stiffness of 15 to 20 kN/m
into the spring mass model, he is expending ~850 watts in mechanical leg-
spring compression when he runs at 10 m/s (assuming no energy recovery from
leg recoil).

I wonder if he expends 200 to 300 watts driving his legs above their resonant
swing frequencies. That would be an interesting calculation.

Ted Andresen
St. Petersburg, Florida