Skip to main content
. 2024 Nov 15;603(1):187–209. doi: 10.1113/JP286938

Table A1.

Force–velocity parameters and peak power of slow MyHC I fibers at 15°C

Men Women Combined P value
Young (31) Old (34) Young (35) Old (34) Young (66) Old (68) Age Sex Age × Sex
Po (mN)
pH 7.0 + 4 mm Pi 0.56 ± 0.15 0.60 ± 0.22 0.59 ± 0.14 0.54 ± 0.17 0.57 ± 0.14 0.57 ± 0.20 0.890 0.572 0.174
pH 6.8 + 12 mm Pi 0.45 ± 0.12 0.51 ± 0.18 0.48 ± 0.12 0.45 ± 0.15 0.47 ± 0.12 0.48 ± 0.17 0.734 0.459 0.106
pH 6.6 + 20 mm Pi 0.41 ± 0.12 0.47 ± 0.17 0.44 ± 0.13 0.41 ± 0.15 0.42 ± 0.13 0.44 ± 0.16 0.887 0.466 0.160
pH 6.2 + 30 mm Pi 0.33 ± 0.09 0.36 ± 0.13 0.34 ± 0.11 0.34 ± 0.13 0.34 ± 0.10 0.35 ± 0.13 0.800 0.515 0.382
Po (kN m−2)
pH 7.0 + 4 mm Pi 94 ± 17 113 ± 20 101 ± 18 113 ± 26 98 ± 18 113 ± 23 0.054 0.972 0.337
pH 6.8 + 12 mm Pi 76 ± 17 98 ± 20 83 ± 17 93 ± 25 80 ± 17 96 ± 21 0.045 0.675 0.269
pH 6.6 + 20 mm Pi 70 ± 18 89 ± 18 74 ± 18 86 ± 24 72 ± 18 87 ± 22 0.041 0.822 0.485
pH 6.2 + 30 mm Pi 57 ± 17 70 ± 16 60 ± 14 71 ± 22 58 ± 15 70 ± 19 0.068 0.812 0.879
V max (fl s−1)
pH 7.0 + 4 mm Pi 1.54 ± 0.19 1.57 ± 0.18 1.56 ± 0.18 1.44 ± 0.20 1.55 ± 0.19 1.51 ± 0.20 0.369 0.372 0.126
pH 6.8 + 12 mm Pi 1.45 ± 0.18 1.48 ± 0.16 1.46 ± 0.16 1.34 ± 0.17 1.46 ± 0.17 1.41 ± 0.18 0.256 0.122 0.092
pH 6.6 + 20 mm Pi 1.36 ± 0.18 1.39 ± 0.14 1.35 ± 0.16 1.25 ± 0.18 1.35 ± 0.17 1.32 ± 0.17 0.434 0.139 0.105
pH 6.2 + 30 mm Pi 1.20 ± 0.14 1.25 ± 0.13 1.22 ± 0.18 1.14 ± 0.16 1.22 ± 0.16 1.20 ± 0.15 0.600 0.497 0.108
Peak power (µN fl s−1)
pH 7.0 + 4 mm Pi 22.4 ± 6.9 24.6 ± 8.9 23.5 ± 7.3 20.7 ± 6.0 23.0 ± 7.1 22.6 ± 7.8 0.660 0.476 0.115
pH 6.8 + 12 mm Pi 20.2 ± 6.6 22.2 ± 8.2 21.2 ± 6.8 18.7 ± 5.6 20.7 ± 6.7 20.5 ± 7.2 0.720 0.471 0.120
pH 6.6 + 20 mm Pi 16.9 ± 5.8 18.5 ± 6.7 16.7 ± 4.9 15.6 ± 5.1 16.8 ± 5.3 17.1 ± 6.1 0.980 0.335 0.224
pH 6.2 + 30 mm Pi 11.0 ± 3.4 12.0 ± 4.5 11.1 ± 3.5 10.2 ± 3.4 11.1 ± 3.4 11.1 ± 4.0 0.954 0.400 0.285
Peak power (W L−1)
pH 7.0 + 4 mm Pi 3.8 ± 0.8 4.7 ± 1.2 4.0 ± 1.0 4.3 ± 0.9 3.9 ± 0.9 4.5 ± 1.0 0.056 0.786 0.319
pH 6.8 + 12 mm Pi 3.4 ± 0.7 4.2 ± 1.0 3.6 ± 1.0 3.9 ± 0.8 3.5 ± 0.9 4.1 ± 0.9 0.049 0.849 0.314
pH 6.6 + 20 mm Pi 2.8 ± 0.6 3.5 ± 0.8 2.9 ± 0.7 3.3 ± 0.7 2.8 ± 0.7 3.4 ± 0.8 0.013 0.589 0.523
pH 6.2 + 30 mm Pi 1.9 ± 0.4 2.3 ± 0.6 1.9 ± 0.5 2.1 ± 0.5 1.9 ± 0.5 2.2 ± 0.5 0.031 0.650 0.697
a/Po
pH 7.0 + 4 mm Pi 0.039 ± 0.007 0.039 ± 0.005 0.037 ± 0.007 0.040 ± 0.007 0.038 ± 0.007 0.039 ± 0.006 0.498 0.802 0.325
pH 6.8 + 12 mm Pi 0.048 ± 0.010 0.044 ± 0.005 0.047 ± 0.012 0.050 ± 0.011 0.047 ± 0.011 0.047 ± 0.009 0.439 0.573 0.289
pH 6.6 + 20 mm Pi 0.047 ± 0.011 0.043 ± 0.005 0.044 ± 0.013 0.049 ± 0.011 0.046 ± 0.012 0.046 ± 0.009 0.991 0.426 0.152
pH 6.2 + 30 mm Pi 0.045 ± 0.014 0.039 ± 0.007 0.040 ± 0.010 0.042 ± 0.013 0.042 ± 0.012 0.040 ± 0.010 0.714 0.894 0.174

Absolute (µN fl s−1) and size‐specific (W L−1) peak power were calculated with the fitted‐parameters from the force–velocity curves. The absolute (mN) and size‐specific (kN m−2) Po for each fibre was the average from all the contractions within each condition. The maximal shortening velocity (V max) was calculated using the Hill equation, and the a/Po ratio is a unitless parameter describing the curvature of the force–velocity relationship. The number of fibres (n) for each cohort is reported in parentheses. Values are the mean ± SD.