Table 1—

Sample characteristics by sex-specific quartiles of HRR at 2 min

TotalSex-specific quartiles
1 (slow)234 (fast)Trend P
HRR Median (minimum, maximum)
 Women42 (1, 116)29 (1, 33)37 (34, 40)44 (41, 48)54 (49, 116)
 Men45 (−8, 95)32 (−8, 36)40 (37, 43)47 (44, 51)57 (52, 95)
Age (years)25.1 ± 3.625.6 ± 3.525.1 ± 3.525.0 ± 3.624.7 ± 3.7<0.01
Race (% black)44.539.440.648.747.7<0.01
Education
 Less than high school (%)5.93.56.55.67.5<0.01
 High school (%)57.254.555.958.159.60.03
 More than high school (%)36.942.037.636.232.9<0.01
Smoking status
 Never (%)61.667.463.159.258.0<0.01
 Former (%)14.714.614.514.514.90.41
 Current (%)23.718.022.326.327.0<0.01
Family history of diabetes (%)4.93.85.15.84.80.21
BMI (kg/m2)24.2 ± 4.524.6 ± 5.124.2 ± 4.324.3 ± 4.523.7 ± 3.9<0.01
Waist circumference (cm)77.4 ± 10.578.7 ± 11.577.4 ± 10.777.4 ± 10.376.2 ± 9.5<0.01
Length of exercise test (min)10.5 ± 2.710.2 ± 2.810.3 ± 2.710.5 ± 2.611.0 ± 2.6<0.01
Resting heart rate (bpm)69.0 ± 10.772.2 ± 10.970.1 ± 10.968.4 ± 10.565.8 ± 9.6<0.01
Maximum heart rate (bpm)185.9 ± 9.1186.6 ± 9.1185.9 ± 8.3185.5 ± 9.3185.7 ± 9.70.10
Increase in heart rate from resting to maximum (bpm)107.9 ± 15.1103.3 ± 15.8105.6 ± 14.8108.6 ± 14.3112.9 ± 13.9<0.01
Estimated METs at peak exercise12.7 ± 2.612.4 ± 2.712.5 ± 2.612.6 ± 2.613.1 ± 2.5<0.01
Poor physical fitness (%)28.044.931.525.014.0<0.01
Physical activity intensity (exercise units)443.6 ± 305.3388.9 ± 274.6434.8 ± 314.7454.4 ± 300.9485.6 ± 317.8<0.01
% of heart rate reserve used during exercise92.4 ± 7.893.0 ± 8.192.3 ± 7.392.1 ± 7.792.4 ± 8.10.30
  • Data are means ± SD, unless otherwise noted. Linear trend test based on F tests (continuous variables) and χ2 tests (categorical variables),

  • Highest quartile (age and sex specific) of heart rate at stage 2 of the exercise test (4 min),

  • Heart rate reserve = ([maximum heart rate - resting heart rate]/[220 − age − resting heart rate]) × 100; <80% was excluded.