%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% http://isb.ri.ccf.org/biomch-l/archives/biomch-l-1995-08/00051.html McMahon says for isometric contraction Peak Stress = 2 kg/cm^2 = 20,000 kg/m^2 = 200,000 N/m^2 = 20 N/cm^2 = 200 KPascals = 2 atmospheres = 0.001 the yield stress of soft steel But other more reliable sources quote peak numbers more like 30 N/cm^2 And less reliable sources quote numbers up to 40 N/cm^2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% http://robotics.eecs.berkeley.edu/~ronf/MFI/TABLES/tables.html Peak strain rate = 5/s This would imply (peak stress and peak strain rate don't occur simultaneously): Peak power per kg = (1/3 peak strain rate) * (1/3 peak stress) * 1/(density of muscle) = (5/s)/3 * (3.5 * 10^5 N/m^2)/3 * (1 m^3/1000 kg) = 200 Nm/s per kg = 200 watts per kg But actually the peak power is about 50 watts per kg. I don't know if this 50 weatts is peak power is during a contraction or averaged over a contraction cycle. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% http://www.insidetri.com/train/tips/articles/1639.0.html Lance Armstrong, as a whole, muscle, fat, bones and all produces about 6-7 watts/kg in the Tour de France. For comparison I, Andy at his best, in 1980 could climb about 800 feet in 16 minutes on my bike. That's (250m)*(1000N)/((90 kg)*(1000s) = almost 3 watts/kg. http://answers.google.com/answers/threadview?id=44907 Another comparison, 2 stroke gas engines are typically 700 watts/kg. That's 15 times better than pure muscle and 100 times better than Lance Armstrong's body viewed as a motor. But Ultralight plane engines can have even twice that power to weight ratio (up to 1500 watts/kg).