Table 2.

Descriptive Statistics of the Dependent and Independent Variables along with Results of their Univariate Associations.

	Mean ± SD or Median (25th-75th Percentile) 95% Confidence Interval	Univariate Correlation Coefficients (Pearson’s r or Spearman’s rho)
		Quadriceps Density, HU (Skeletal Muscle Fat)†	Intermuscular Adipose Tissue, sq.cm	Subcutaneous Adipose Tissue, sq.cm
Dependent Variables
Quadriceps Strength, Newton-meters‡	141.6 (114.8 – 165.9) 134.3 – 158.7	.454*	.072	.075
Single leg stance, seconds‡	12.7 (3.2–23.5) 11.0 −16.3	.508*	−.211	−.071
Gait speed, meters/second	1.06 ± 0.25 0.99 – 1.12	.397*	−.389*	−.219
5-Chair-stand time, seconds	12.5 (10.4–15.1) 12.0 −14.9	−.244	.270*	.128
Stair ascend time, seconds	6.3 (5.1 – 7.7) 6.1 −7.6	−.576*	.372*	.289*
HAQ	0.88 (0.38–1.25) 0.72 – 1.04	−.418*	.424*	.190
Physical Activity, minutes/day	34.0 (16.0 −47.0) 31.1 −52.4	.578**	−.388*	−.321*
Independent Variables‡
Skeletal muscle fat (quadriceps density, HU)	46.4 ± 4.7 45.1 – 47.6
Intermuscular adipose tissue area (sq. cm)	11.8 (7.9 – 17.3) 11.4 – 15.3
Subcutaneous adipose tissue area (sq.cm)	106.3 (69.4 – 153.4) 101.3 – 134.9

N = 60, except for HAQ (N = 59), Gait speed (N = 59), and Chair-stand (N=58) due to missing data, and Physical Activity (N=51) due to insufficient activity monitor data (<10 hours per day on 4 days).

^*significant at alpha level 0.05

^†Higher values of muscle density corresponds to lower amount of skeletal muscle fat

^‡Values represent the averages of the right and left leg.

HAQ: Health Assessment Questionnaire, HU: Hounsfeld Units, sq.cm: square centimeter