Testosterone is associated with age-related changes in bone health status, muscle strength and body composition in men

Figures & data

Table I.  General characteristics of the study population.

Variable	Chinese (n = 223)	Malay (n = 112)	Overall (n = 335)	Sig.
Age	53.17 (8.97)	56.34 (10.64)	54.23 (9.66)	s
Height (cm)	167.00 (6.33)	164.63 (6.00)	166.21 (6.31)	s
Weight (kg)	68.25 (11.05)	74.33 (15.20)	70.28 (12.89)	s
BMI (kg/m2)	24.42 (3.48)	27.37 (5.11)	25.43 (4.32)	s
Body fat (%)	22.83 (5.45)	25.46 (7.12)	23.71 (6.19)	s
FFM (kg)	52.27 (6.23)	54.64 (7.26)	53.06 (6.67)	s
SOS (m/s)*	1511.7 (27.62)	1518.36 (24.73)	1513.94 (26.84)	ns
Handgrip (kg)	34.37 (6.06)	31.84 (7.28)	33.53 (6.60)	s
Total T (nmol/l)	18.97 (7.71)	18.66 (6.27)	18.76 (6.78)	ns
Bio T (nmol/l)	10.11 (3.31)	10.38 (3.46)	10.20 (3.36)	ns
Free T (nmol/l)	0.36 (0.12)	0.38 (0.13)	0.37 (0.12)	ns
SHBG (nmol/l)	49.85 (26.11)	46.84 (25.63)	48.8 (25.95)	ns

BMI, body mass index; FFM, fat-free mass; T, testosterone; SOS, calcaneal speed of sound; SHBG, sex hormone binding globulin.

The values of all variables were expressed in mean (standard deviation). ‘Sig.’ indicates significance of the independent t-test between Chinese and Malay subjects. Letter ‘s’ indicates a significance difference (p < 0.05) in the variable tested while ‘ns’ indicates an insignificant difference (p > 0.05).

*Insignificant after adjustment for height and body weight.

Table II.  Linear regression results when outcome of aging is regressed against age.

Variable	Age
	Regression coefficient
	Unstandardized	standardized	p
SOS (m/s)	–0.546	–0.197	<0.001
FFM (kg)	–0.166	–0.241	<0.001
Body Fat (%)	0.051	0.079	<0.05
Handgrip (kg)	–0.287	–0.42	<0.001
Total T (nmol/l)	–0.123	–0.175	<0.001
Bio T (nmol/l)	–0.144	–0.414	<0.001
Free T (nmol/l)	–0.005	–0.378	<0.001
SHBG (nmol/l)	0.622	0.231	<0.001

FFM, fat-free mass; T, testosterone; SOS, calcaneal speed of sound; SHBG, sex hormone binding globulin.

Unstandardized regression coefficient (B) indicates the change of the studied variable when the predictor (age) changes by 1 unit. Standardized regression coefficient (β) measures the changes when the predictor changes by one standard deviation. The predictor in this table is age.

Table III.  Linear regression results when outcome of aging is regressed against testosterone levels.

Variable	Total T			Bio T			Free T
	Regression coefficient			Regression coefficient			Regression coefficient
	unstandardized	standardized	p	unstandardized	standardized	p	unstandardized	standardized	p
SOS (m/s)	0.454	0.115	0.062	1.075	0.132	0.02	32.236	0.145	0.011
FFM (kg)	0.056	0.057	0.187	0.229	0.119	0.003	6.722	0.122	0.002
Body fat (%)	–0.062	–0.068	0.017	–0.067	–0.038	0.153	–2.444	–0.048	0.071
Handgrip (kg)	0.109	0.112	0.065	0.271	0.142	0.008	11.937	0.219	<0.001

FFM, fat-free mass; T, testosterone; SOS, calcaneal speed of sound; SHBG, sex hormone binding globulin.

Unstandardized regression coefficient (B) indicates the change of the studied variable when the predictor (testosterone levels) changes by 1 unit. Standardized regression coefficient (β) measures the changes when the predictor changes by one standard deviation. The predictors in this table are the testosterone measurement.