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Table 3 Cadence thresholds (steps/min) for moderate and vigorous relative intensity based on regression and ROC curve analyses

From: Cadence (steps/min) and relative intensity in 21 to 60-year-olds: the CADENCE-adults study

    Age Groups (years)  
Group 1: Ages 21–30 Group 2: Ages 31–40 Group 3: Ages 41–50 Group 4: Ages 51–60
Regression ROC Regression ROC Regression ROC Regression ROC
Moderate Intensity
  ≥ 64% HRmax
  Threshold (steps/min) 127.5 (110.4–144.7) 115.5 (114–122.5) 126 (107.2–144.9) 113.5 (110.5–120.5) 122.7 (101.5–143.9) 112.9 (108.7–117.2) 116.1 (65.1–135.9) 104.8 (100.8–112.5)
  Se 60 100 57.8 91.1 57.7 88.5 52.2 85.5
  Sp 95.2 78.4 93.6 79.5 92.5 80.3 89.1 68.8
  PPV 64.9 40.8 60.5 43.2 61.2 47.9 60 46.1
  NPV 94.1 100 92.9 98.1 91.4 97.1 85.7 93.8
  Accuracy 90.6 81.2 88.3 81.2 86.6 81.7 80.3 72.8
  AUC 94.4 (91.8–97) 92.2 (88.8–95.7) 88.5 (84–93.1) 82.9 (77.5–88.2)
  ≥ 40% HRR
  Threshold (steps/min) 123.8 (112.2–135.5) 118.5 (114–121.5) 121.3 (108.2–134.5) 114.5 (109.5–119.5) 119.6 (102.9–136.4) 112.9 (110.7–116.1) 113.8 (99.7–128) 106 (100.9–113)
  Se 79.6 91.8 72.5 94.1 71.7 90 72.6 91.9
  Sp 94.2 90.8 91.1 81.8 90.7 82.9 89.5 78.5
  PPV 72.2 65.2 61.7 50.5 65.2 56.3 65.2 53.8
  NPV 96.1 98.3 94.4 98.6 92.9 97.1 92.3 97.3
  Accuracy 91.9 90.9 88 83.8 86.9 84.3 85.9 81.4
  AUC 96.7 (94.9–98.5) 93.9 (91.3–96.6) 90.6 (86.7–94.6) 91.6 (88.4–94.9)
  ≥ 12 RPE
  Threshold (steps/min) 126.5 (109.7–143.3) 114.5 (109.5–118.5) 120.2 (93.5–147) 113.5 (103.5–115.5) 117.7 (89.6–145.9) 104.6 (102.6–112.1) 113.3 (85.8–140.9) 103.6 (96.5–111.4)
  Se 51.6 93.8 58.8 75.3 56.7 91.8 56.7 78.4
  Sp 96.7 80.8 93.3 86.2 91.4 77 91.7 81.3
  PPV 80.5 56.1 76.9 67.4 75.3 65 77.5 67.9
  NPV 88.4 98 85.7 90.2 82 95.3 80.8 88.2
  Accuracy 87.4 83.5 83.8 83.2 80.4 81.7 80.0 80.3
  AUC 93.7 (91–96.4) 87.8 (83.6–91.9) 89.2 (85.6–92.8) 86.8 (82.7–91)
Vigorous Intensity
  ≥ 77% HRmax
  Threshold (steps/min) 144.1 (126.9–148) 127.5 (127.5–133.5) 142.6 (123.8–156) 121.5 (121.5–128.5) 143.6 (122.5–157.4) 123.2 (116.3–129.7) 132.8 (113.1–151.8) 113 (110.2–124.6)
  Se 22.2 100 15.4 100 17.6 100 28.6 100
  Sp 99.7 90.7 98.6 84.1 99.3 78.2 98.2 72.8
  PPV 66.7 24.3 33.3 21.7 60 21.3 44.4 15.7
  NPV 97.7 100 96.4 100 95.3 100 96.4 100
  Accuracy 97.4 90.9 95.1 84.8 94.8 79.4 94.8 74.1
  AUC 96.4 (93.7–99.2) 94.4 (91.4–97.4) 94.3 (90.7–97.8) 92.2 (87.3–97.1)
  ≥ 60% HRR
  Threshold (steps/min) 140.3 (128.6–148) 127.5 (127.5–133.5) 140.2 (127–153.6) 121.5 (121.5–126.5) 139.3 (122.5–156.2) 117.2 (116.3–128.1) 131.6 (117.6–145.9) 113 (110.2–126.2)
  Se 30 100 12.5 100 38.1 100 35.7 100
  Sp 99.3 91 98.6 85 98.6 79.3 97.8 72.8
  PPV 60 27 33.3 26.7 66.7 26.3 45.5 15.7
  NPV 97.7 100 95.4 100 95.6 100 96.8 100
  Accuracy 97.1 91.3 94.2 85.8 94.4 80.7 94.8 74.1
  AUC 96.9 (94.6–99.2) 94.3 (91.6–97.1) 94.6 (91.5–97.8) 92.6 (87.7–97.4)
  ≥ 14 RPE
  Threshold (steps/min) 143.9 (127.2–148.0) 124.5 (114.5–130.5) 139.6 (112.9–156.0) 121.5 (104.5–129.5) 138.7 (110.6–157.4) 120.9 (120.5–122.1) 135.2 (107.8–151.8) 122.2 (110.2–126.0)
  Se 12.5 87.5 21.1 84.2 19.0 90.5 23.8 81.0
  Sp 99.7 88.4 99.3 84.8 97.2 85.6 99.3 92.9
  PPV 66.7 29.2 66.7 26.7 33.3 31.7 71.4 47.2
  NPV 95.4 99.2 95.0 98.8 94.2 99.2 94.3 98.4
  Accuracy 95.1 88.3 91.8 84.8 91.8 85.9 93.8 92.1
  AUC 94.2 (90.2–98.3) 90.0 (83.7–96.3) 88.2 (80.7–95.8) 92.7 (87.9–97.5)
  1. The thresholds are represented as means (95% Prediction Intervals) for segmented regression and means (99% Confidence Intervals) for ROC Receiver Operating Characteristic. Classification accuracy analyses to calculate Se Sensitivity, Sp Specificity, PPV Positive Predictive Value, NGV Negative Predictive Value and Accuracy were performed independently on these two optimal thresholds derived from segmented regression and ROC analysis, therefore yielding two values for each classification accuracy metric. AUC Area under the curve. HR maximum [HRmax] = 220 - age. Heart rate reserve [HRR] = HRmax - HRresting. RPE Rate of Perceived Exertion