Contractile properties of zebra finch and budgerigar pectoralis fascicles
| Parameter . | Zebra finches . | Budgerigars . |
|---|---|---|
| Peak isometric, tetanic stress (kN m–2) | 167±10 | 220±12 |
| Twitch:tetanus ratio | 0.35±0.07 | 0.51±0.07 |
| Twitch rise time (ms) | 9.7±0.7 | 18.1±0.5 |
| Twitch 50% relaxation time (ms) | 9.8±0.7 | 22.1±2.0 |
| Twitch 90% relaxation time (ms) | 20.2±2.5 | 48.2±4.0 |
| Maximum shortening velocity (Vmax, L0s–1) | 21.3±1.0 | 14.7±0.7 |
| Velocity at maximum power (L0 s–1) | 9.8±0.2 | 5.6±0.2 |
| Relative force at maximum power (P/P0) | 0.50±0.01 | 0.44±0.01 |
| Power ratio | 0.22±0.01 | 0.17±0.003 |
| Maximum isotonic power (W kg–1) | 730±58 | 522±37 |
| Parameter . | Zebra finches . | Budgerigars . |
|---|---|---|
| Peak isometric, tetanic stress (kN m–2) | 167±10 | 220±12 |
| Twitch:tetanus ratio | 0.35±0.07 | 0.51±0.07 |
| Twitch rise time (ms) | 9.7±0.7 | 18.1±0.5 |
| Twitch 50% relaxation time (ms) | 9.8±0.7 | 22.1±2.0 |
| Twitch 90% relaxation time (ms) | 20.2±2.5 | 48.2±4.0 |
| Maximum shortening velocity (Vmax, L0s–1) | 21.3±1.0 | 14.7±0.7 |
| Velocity at maximum power (L0 s–1) | 9.8±0.2 | 5.6±0.2 |
| Relative force at maximum power (P/P0) | 0.50±0.01 | 0.44±0.01 |
| Power ratio | 0.22±0.01 | 0.17±0.003 |
| Maximum isotonic power (W kg–1) | 730±58 | 522±37 |
Values are means ± s.e.m.; N=7 zebra finches, isometric parameters, N=5 zebra finches, force–velocity parameters, N=9 budgerigars, all parameters