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Table 1 Physical characteristics, habitual daily activities, variables of segmental bioelectrical impedance spectroscopy, and neuromuscular properties

From: Association of age-related decrease in intracellular-to-total water ratio with that in explosive strength of the plantar flexors: a cross-sectional study

  Young (n = 29) Older (n = 30) Main effect of age Effect size (η2)
Mean SD Min Max 95% CI Mean SD Min Max 95% CI P Age Sex
Physical characteristics
 Age (years) 23 3 21 33 22–24 72 5 64 83 70–74    
 Height (cm) 165.3 8.4 152.6 181.2 162.1–168.5 159.8 9.0 141.3 176.4 156.3–163.2 < 0.001 0.086 0.571
 Weight (kg) 59.8 11.9 40.3 86.3 55.3–64.3 60.1 11.9 38.2 87.2 55.1–64.1 0.808 0.001 0.449
 BMI (kg/m2) 21.7 2.8 16.3 29.1 20.6–22.8 23.4 3.6 17.9 32.7 21.9–24.6 0.034 0.069 0.112
 Leg length (cm) 37.3 2.7 32.5 41.5 36.3–38.3 36.0 2.5 32.5 40.5 35.0–36.9 0.018 0.056 0.414
Habitual daily activities
 Light (min/day) 621 115 465 857 577–665 715 121 460 947 670–760 0.003 0.137 0.066
 Moderate (min/day) 67 23 31 145 59–76 56 19 17 99 49–63 0.036 0.071 0.076
 Vigorous (min/day) 3 4 0 17 1–4 1 2 0 8 0–1 0.003 0.146 0.007
S-BIS variables
 ICW (mL) 894.7 265.4 411.7 1323.6 793.7–995.6 773.5 193.9 461.1 1262.9 701.0–845.9 0.007 0.060 0.509
 ICW/TW 0.710 0.033 0.633 0.762 0.697–0.723 0.661 0.039 0.567 0.736 0.647–0.676 < 0.001 0.309 0.151
Explosive muscle strength
 RTD0–50 (Nm/s) 145.0 74.1 30.3 288.8 116.8–173.2 87.7 51.6 27.0 198.0 68.4–107.0 0.001 0.170 0.055
 RTD50–100 (Nm/s) 431.7 225.9 113.1 882.4 345.8–517.6 271.3 156.6 65.2 584.5 212.9–329.8 0.001 0.146 0.139
 RTD100–200 (Nm/s) 382.4 143.9 84.0 681.0 327.7–437.2 287.0 125.7 100.4 511.7 240.1–334.0 0.003 0.109 0.233
 nRTD0–50 (%/s) 115.6 50.3 18.3 201.5 96.4–134.7 81.1 40.1 22.1 169.0 66.1–96.0 0.006 0.129 0.000
 nRTD50–100 (%/s) 334.9 135.9 105.3 554.4 283.3–386.8 247.3 114.3 53.2 498.8 204.6–290.0 0.009 0.110 0.035
 nRTD100–200 (%/s) 297.5 70.9 110.0 430.2 270.5–324.5 263.6 88.2 106.8 408.3 230.6–296.4 0.109 0.043 0.054
Maximal muscle strength
 PTMVC (Nm) 111.8 37.7 38.2 184.8 97.4–126.1 88.1 25.0 40.0 140.7 78.8–97.4 0.001 0.118 0.311
Twitch contractile properties
 PTtwitch (Nm) 21.4 5.6 10.2 34.4 19.3–23.5 17.1 4.1 11.0 27.0 15.6–18.7 < 0.001 0.159 0.190
 RTDtwitch (Nm/s) 176.6 50.1 71.5 298.9 157.5–195.7 125.4 31.1 77.4 200.0 113.8–137.0 < 0.001 0.274 0.187
 TPTtwitch (s) 0.122 0.012 0.098 0.164 0.118–0.127 0.136 0.010 0.110 0.159 0.133–0.140 < 0.001 0.293 0.045
Neuromuscular activity
 VA (%) 87.2 14.4 50.0 100.0 81.7–92.6 82.9 16.1 30.9 99.5 76.9–88.9 0.297 0.018 0.060
 nRMS-MVC (%Mmax) 3.59 2.01 1.30 8.95 2.83–4.35 3.32 1.78 0.98 6.89 2.66–3.98 0.579 0.004 0.277
 nRMS-RTD0-50 (%Mmax) 1.49 0.98 0.27 3.32 1.12–1.87 1.44 1.00 0.14 4.76 1.05–1.81 0.835 0.001 0.029
 nRMS-RTD50-100 (%Mmax) 2.90 1.57 0.75 6.54 2.29–3.49 2.81 1.66 0.33 6.43 2.18–3.42 0.859 0.001 0.115
 nRMS-RTD100-200 (%Mmax) 3.05 1.62 0.79 7.68 2.44–3.67 3.03 1.97 0.67 8.07 2.29–3.77 0.995 0.000 0.130
  1. BMI body mass index, CI confidence interval, ICW intracellular water, Max maximum, Min minimum, MVC maximal voluntary contraction, nRMS normalized root mean square, nRTD normalized rate of torque development, PT peak torque, RTD rate of torque development, SD standard deviation, TPT time-to-peak torque, VA voluntary activation, BMI body mass index, CI confidence interval, ICW intracellular water, Max maximum, Min minimum, MVC maximal voluntary contraction, nRMS normalized root mean square, nRTD normalized rate of torque development, PT peak torque, RTD rate of torque development, SD standard deviation, TPT time-to-peak torque, VA voluntary activation