Table 1. Subject characteristics.

Subjects and Characteristics	Group 1	Group 2	Group 3
All subjects
No. of subjects	20	20	20
Age (y)*	26.5±2.7	39.9±4.1	61.4±6.2
Body mass index* †	21.5±3.1	22.3±2.5	25.0±2.9
WOMAC pain score	0	0	0
Women
No. of subjects	10	10	10
Age (y)*	25.8±1.8	39.7±3.9	61.4±5.3
Age range (y)	22–28	35–47	50–70
Body mass index*	20.2±2.7	21.3±2.3	25.9±2.9
Men
No. of subjects	10	10	10
Age (y)*	27.2±3.4	40.0±4.6	59.7±5.9
Age range (y)	22–32	35–48	50–69
Body mass index*	22.7±2.9	23.3±2.5	23.8±2.8

^*Mean values ± standard deviations.

^†There was a significant difference (P<0.05) in BMI between Group 2 and Group 3 but not a significant difference in age between Group 1 and Group 2.