CARR, J.A.*; ELLERBY, D.J.; MARSH, R.L.; HERR, H.: Work and Power Output in Knee Flexor Muscle of the Frog (Rana pipiens)
Numerous studies have reported on work and power output of various skeletal muscles. However, relatively few studies have reported on frog muscle. We measured work and power output in the sartorius and the dorsal semitendinosus, two knee flexor muscles of the frog. Peak tetanic force (P0), force-velocity data and work loop measurements were recorded in vitro on both the sartorius and the dorsal semitendinosus. Work loop settings were adjusted to maximize the work per cycle. The strain settings for the sartorius measurements ranged from 6.0% to 10.0% and the frequency was 5 Hz. For the dorsal semitendinosus work loops, the strain was set between 3.00% and 7.00% and the frequency was set at either 4.0 Hz or 5.0 Hz. The average P0 of the sartorius was 28 N/cm2, the average Vmax was 9 l/s, and the power ratio was 0.115. The average maximum work per cycle calculated from the work loop data was 19 J/kg, the average power was 94 W/kg, and the peak power was 330 W/kg. The average P0 for the dorsal semitendinosus was lower than that of the sartorius. However, the average Vmax and the power ratio measurements were similar. The average work per cycle, the average power and the peak power were lower in the dorsal semitendinosus than in the sartorius. Overall, our values are slightly higher than those previously reported. This may be due to setting a higher frequency when performing the work loops. This research was supported by NIH grant AR47337 and a DARPA contract.
