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. 2019 Aug 21;7:181. doi: 10.3389/fbioe.2019.00181

Table 1.

Neuromuscular function of the wrist flexors depending on the wrist joint angle.

Wrist joint angle P-values
Extension (– 30°) Neutral (0°) Flexion (30°) −30° vs. 0° −30° vs. 30° 30° vs. 0°
Maximal voluntary torque (N·m) 16.08 ± 2.78 19.17 ± 3.12 18.46 ± 2.46 <0.001** 0.001** 0.552
Voluntary activation (%) 98.11 ± 2.65 97.40 ± 3.52 96.06 ± 4.05 0.742 0.005** 0.055
Central activation ratio (%) 99.21 ± 1.05 99.20 ± 1.01 98.89 ± 1.06 n.a. n.a. n.a.
   Interpolated twitch torque (N·m) 0.118 ± 0.154 0.149 ± 0.186 0.200 ± 0.191 1 0.039* 0.186
   Control twitch torque (N·m) 6.02 ± 0.93 5.68 ± 0.85 5.17 ± 0.87 0.192 0.002** 0.017*
RMS·M−1
   Flexor carpi radialis (FCR) 0.088 ± 0.023 0.087 ± 0.030 0.084 ± 0.030 n.a. n.a. n.a.
   Extensor carpi radialis brevis (ECRB) 0.042 ± 0.018 0.041 ± 0.016 0.046 ± 0.015 n.a. n.a. n.a.
   ECRB·FCR−1 ratio 0.50 ± 0.24 0.52 ± 0.23 0.62 ± 0.30 1 0.021* 0.174
Mmax (mV)
   FCR 9.00 ± 3.03 9.29 ± 2.95 10.63 ± 3.77 1 0.009** 0.033*
   ECRB 6.98 ± 2.53 6.90 ± 2.05 6.47 ± 2.03 n.a. n.a. n.a.
Peak twitch torque (N·m)
   SS 1.58 ± 0.34 1.25 ± 0.28 0.98 ± 0.24 <0.001** <0.001** <0.001**
   PS100 4.01 ± 0.65 3.44 ± 0.66 2.90 ± 0.51 <0.001** <0.001** <0.001**
   SSPOT 2.99 ± 0.38 2.69 ± 0.44 2.29 ± 0.36 0.006** <0.001** <0.001**
   PS100POT 6.29 ± 0.99 5.93 ± 0.92 5.40 ± 0.95 0.31 <0.001** 0.06
Rate of twitch torque development (N·m·s–1)
   SS 23.16 ± 4.27 18.55 ± 3.46 15.63 ± 4.00 <0.001** <0.001** 0.032*
   PS100 52.32 ± 9.22 47.10 ± 8.76 40.40 ± 7.12 0.009** <0.001** 0.001**
   SSPOT 53.42 ± 8.91 50.30 ± 7.84 45.01 ± 7.11 0.46 0.001** 0.067
   PS100POT 86.32 ± 14.74 85.98 ± 12.68 83.27 ± 15.70 n.a. n.a. n.a.
Rate of twitch torque relaxation (N·m·s–1)
   SS 12.77 ± 3.05 11.09 ± 2.94 9.65 ± 2.87 0.009** 0.001** 0.016*
   PS100 31.60 ± 5.44 30.68 ± 5.35 29.30 ± 5.93 n.a. n.a. n.a.
   SSPOT 30.01 ± 4.15 30.37 ± 4.05 27.91 ± 4.64 n.a. n.a. n.a.
   PS100POT 52.15 ± 9.71 56.36 ± 6.86 57.76 ± 7.94 0.114 0.038* 1
Electromechanical delay (ms)
   SS 9.04 ± 0.82 9.80 ± 1.03 11.61 ± 2.65 0.009** 0.004** 0.017*
   PS100 9.11 ± 0.78 9.87 ± 1.07 11.70 ± 2.55 0.004** 0.002** 0.008**
   SSPOT 8.56 ± 0.96 8.94 ± 0.85 10.72 ± 1.63 0.556 <0.001** <0.001**
   PS100POT 8.22 ± 1.18 9.22 ± 1.03 10.67 ± 1.70 0.073 <0.001** 0.001**
Twitch contraction time (ms)
   SS 68.24 ± 5.27 67.31 ± 5.29 63.41 ± 8.49 1 0.029* 0.211
   PS100 77.09 ± 5.85 73.02 ± 3.98 71.94 ± 5.61 <0.001** 0.002** 0.757
   SSPOT 56.56 ± 6.18 53.61 ± 4.98 51.78 ± 8.97 0.173 0.074 0.701
   PS100POT 73.06 ± 4.01 69.06 ± 5.15 65.44 ± 6.52 0.003** <0.001** 0.036*
Twitch half-relaxation time (ms)
   SS 63.17 ± 9.92 57.63 ± 7.67 51.97 ± 6.94 0.019* 0.002** 0.010**
   PS100 63.96 ± 7.64 56.09 ± 5.52 50.09 ± 7.08 0.001** <0.001** 0.001**
   SSPOT 50.33 ± 7.10 44.78 ± 8.50 41.67 ± 6.19 <0.001** <0.001** 0.406
   PS100POT 61.00 ± 7.13 52.72 ± 6.23 46.72 ± 5.01 <0.001** <0.001** <0.001**
Percentage changes peak twitch torque
   SS vs. SSPOT 92.84 ± 27.71 119.59 ± 34.52 142.88 ± 49.17 <0.001** <0.001** 0.111
   PS100 vs. PS100POT 57.82 ± 15.44 75.75 ± 26.12 88.74 ± 28.77 0.010** 0.002** 0.189
   SS vs. PS100 158.89 ± 47.04 180.52 ± 54.37 205.49 ± 60.15 0.013* <0.001** 0.002**
   SSPOT vs. PS100POT 111.23 ± 26.52 122.66 ± 28.02 136.56 ± 31.61 0.074 <0.001** 0.063

Please note that post-hoc comparisons are only available if the ANOVA with repeated measures indicated a statically significant difference (P-values in bold are significant,

*

P ≤ 0.050,

**

P ≤ 0.010). n. a., not applicable because the ANOVA did not indicate a main effect of angle; RMS·M−1, root mean square of the EMG signal normalized to the maximal M-wave (Mmax); SS, unpotentiated peak twitch torque evoked by a single stimulus; PS100, unpotentiated peak twitch torque evoked by paired stimuli at 100 Hz [inter-stimulus interval (ISI) 10 ms]; SSPOT, potentiated peak twitch torque evoked by a single stimulus; PS100POT, potentiated peak twitch torque evoked by paired stimuli at 100 Hz (ISI 10 ms). Values are expressed as means ± standard deviations.

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