Table 1.
Measured dynamics and modelled energetics (mean ± SD; n = 14) for the gastrocnemius medialis (GM) muscle and Achilles tendon (AT).
| Variable | Control | Stiff | Stiffer | Stiffest |
|---|---|---|---|---|
| Erun (J kg−1 m−1) | 4.85 ± 0.31 | 4.85 ± 0.37 | 4.75 ± 0.36 | 4.85 ± 0.29 |
| GM fascicle length at heel-strike (mm) | 52.0 ± 5.0 | 51.9 ± 5.7 | 51.2 ± 5.4 | 51.7 ± 5.4 |
| GM fascicle length at toe-off (mm) | 34.6 ± 4.9 | 35.6 ± 4.7 | 35.7 ± 4.9 | 36.2 ± 4.7 |
| GM total length change (mm) | − 17.4 ± 2.1 | − 16.3 ± 2.4 | − 15.5 ± 2.3* | − 15.5 ± 2.3* |
| Average GM shortening velocity (mm s−1) | − 69.0 ± 10.9 | − 63.2 ± 9.4* | − 60.1 ± 9.2* | − 59.6 ± 9.2* |
| GM efficiency (%) | 35.5 ± 4.0 | 35.2 ± 4.7 | 35.8 ± 4.5 | 35.2 ± 4.3 |
| GM energy cost (J kg−1) | 0.237 ± 0.043 | 0.226 ± 0.047 | 0.231 ± 0.057 | 0.222 ± 0.054 |
| GM fascicle work (J kg−1) | 0.084 ± 0.015 | 0.078 ± 0.013 | 0.082 ± 0.017 | 0.077 ± 0.017 |
| Peak GM force (N kg−1) | 11.63 ± 1.40 | 11.73 ± 1.29 | 11.94 ± 1.51 | 11.81 ± 1.48 |
| GM force per crossbridge (pN) | 2.55 ± 0.07 | 2.59 ± 0.05 | 2.60 ± 0.05* | 2.61 ± 0.05* |
| In-series sarcomeres (count in 103) | 30.521 ± 3.490 | 31.193 ± 3.812 | 31.019 ± 3.841 | 31.525 ± 3.406 |
| Cycles per crossbridge (count) | 46.01 ± 6.10 | 43.15 ± 5.17 | 41.60 ± 5.59* | 41.22 ± 5.30* |
| AT energy return (J kg−1) | 0.15 ± 0.03 | 0.17 ± 0.04* | 0.18 ± 0.04* | 0.19 ± 0.05* |
| AT force (N kg−1) | 58.96 ± 6.69 | 59.76 ± 6.47 | 60.92 ± 7.68 | 60.38 ± 7.60 |
*Significant (p ≤ 0.017) differences compared to Control.