Table 3.
Moment arm lengths
| Muscle | Joint | Linear estimate*r (SD) (m) | r at max angle (m) | r at min angle (m) | r mean (SD) (m) | r mid-stance (m) | Fascicle length/r(m) |
|---|---|---|---|---|---|---|---|
| Ambiens* | Hip | (0.086 (0.016)) | 0.095 | 0.069 | 0.076 (0.015) | 0.076 | 0.62 |
| Caudofemoralis | Hip | (–0.067 (0.015)) | –0.086 | –0.026 | –0.053 (0.025) | –0.042 | 2.39 |
| Flexor cruris lateralis | Hip | (–0.123 (0.042)) | –0.156 | –0.061 | –0.101 (0.031) | –0.087 | 2.20 |
| Flexor cruris medialis* | Hip | –0.058 (0.013) | –0.058 | –0.058 | –0.058 (0.013) | –0.058 | 0.59 |
| Iliofemoralis externus* | Hip | (0.037 (0.017)) | 0.046 | 0.031 | 0.038 (0.019) | 0.034 | 1.47 |
| Iliofibularis | Hip | (–0.136 (0.037)) | –0.144 | –0.083 | –0.090 (0.051) | –0.071 | 2.86 |
| Iliotibialis cranialis† | Hip | 0.133 (0.013) | 0.133 | 0.133 | 0.133 (0.013) | 0.133 | 2.05 |
| Iliotibialis lateralis* | Hip | (–0.045 (0.018)) | –0.069 | –0.014 | –0.038 (0.026) | –0.022 | 3.21 |
| Iliotrochantericus caudalis* | Hip | (0.047 (0.014)) | 0.059 | 0.038 | 0.043 (0.012) | 0.043 | 1.05 |
| Iliotrochantericus cranialis* | Hip | (0.050 (0.012)) | 0.074 | 0.031 | 0.045 (0.007) | 0.040 | 1.40 |
| Pubo-ischio-femoralis* | Hip | (–0.111 (0.012)) | –0.139 | –0.051 | –0.081 (0.031) | –0.071 | 0.90 |
| Ambiens | Knee | –0.027 (0.010) | –0.027 | –0.027 | –0.027 (0.010) | –0.027 | 1.74 |
| Femorotibialis externus | Knee | –0.015 (0.009) | –0.015 | –0.015 | –0.015 (0.009) | –0.015 | 3.30 |
| Femorotibialis medius | Knee | (–0.057 (0.013)) | –0.045 | –0.070 | –0.055 (0.013) | –0.054 | 1.78 |
| Gastrocnemius (caudalis) | Knee | (0.029 (0.018)) | 0.044 | –0.003 | 0.019 (0.015) | 0.028 | 5.26 |
| Gastrocnemius (lateralis) | Knee | 0.009 (0.010) | 0.009 | 0.009 | 0.009 (0.010) | 0.009 | n/a |
| Gastrocnemius (medialis)* | Knee | (0.007 (0.006)) | 0.019 | 0.006 | 0.009 (0.008) | 0.012 | n/a |
| Iliofibularis | Knee | (0.107 (0.016)) | 0.119 | 0.083 | 0.095 (0.017) | 0.106 | 2.71 |
| Extensor digitorum longus | Ankle | 0.018 (0.004) | 0.018 | 0.018 | 0.018 (0.004) | 0.018 | 3.96 |
| Flexor digitorum longus* | Ankle | –0.024 (0.003) | –0.024 | –0.024 | –0.024 (0.005) | –0.024 | 1.72 |
| Fibularis longus | Ankle | 0.026 (0.002) | 0.026 | 0.026 | 0.026 (0.002) | 0.026 | 2.40 |
| Flexors (FPDIII, FPDIV, FPetPDIII) | Ankle | (–0.025 (0.006)) | –0.037 | –0.017 | –0.025 (0.007) | –0.034 | 0.80 |
| Gastrocnemius* | Ankle | (–0.040 (0.006)) | –0.052 | –0.031 | –0.038 (0.008) | –0.049 | 2.42 |
| Tibialis cranialis | Ankle | 0.028 (0.003) | 0.028 | 0.028 | 0.028 (0.003) | 0.028 | 0.46 |
| Extensor digitorum longus† | MTP | (0.014 (0.004)) | 0.009 | 0.022 | 0.014 (0.002) | 0.010 | 4.65 |
| Flexor digitorum longus | MTP | (–0.029 (0.006)) | –0.042 | –0.015 | –0.027 (0.006) | –0.040 | 1.56 |
| Flexors (FPDIII, FPDIV, FPetPDIII) | MTP | (–0.034 (0.007)) | –0.053 | –0.015 | –0.032 (0.009) | –0.050 | 0.63 |
N = 6 for all muscles except where indicated.
*
n = 5
†
n = 4.
Linear estimates are shown for all muscles as a comparison with the actual variation in moment arm observed through the range of motion, and for muscles where the moment arm was found to change with joint angle these data are shown in parentheses.
Maximum and minimum angles are those defined by the range of motion of each joint during level running.