The influence of dairy consumption, sedentary behaviour and physical activity on bone mass in Flemish children: a cross-sectional study

Table 1 Subject characteristics for the whole study group and for boys and girls separately, as well as the p-value for the comparison between boys and girls

	Whole group		Boys		Girls		Boys versus girls
	N	Mean (SD)	N	Mean (SD)	N	Mean (SD)	p-value
Socio-demographic
Age (years)	272	9.8 (1.4)	133	9.8 (1.5)	139	9.8 (1.4)	0.86^a
Height (m)	272	1.4 (0.1)	133	1.4 (0.1)	139	1.4 (0.1)	0.81^a
Tanner stage	272		133		139		0.22^b
No signs of puberty (%)		71		74		68
Signs of puberty (%)		29		26		32
PEL Level (≤3/4/5or 6) (%)	263	32.7/14.8/52.5	128	28.1/14.4/57.8	135	35.0/15.6/47.4	0.22 ^b
DXA: Whole body minus head	272		133		139
BMC (g)		777 (177)		770 (165.5)		784 (188)	0.79^c
BMC z-score		−0.20 (0.91)		−0.19 (0.91)		−0.20 (0.92)	0.93^a
Areal BMD (g/cm²)		0.68 (0.08)		0.68 (0.07)		0.68 (0.08)	0.73^a
Areal BMD z-score		−0.17 (0.86)		−0.16 (0.83)		−0.18 (0.89)	0.84^a
DXA: Whole body	272		133		139
Fat mass (g)		8540 (3646)		7313 (2816)		9717 (3625)	<0.01^c
FMI (kg/m²)		4.27 (1.54)		3.65 (1.16)		4.86 (1.62)	<0.01^c
Lean mass (g)		24169 (4750)		24522 (4401)		23832 (5055)	0.23^a
FFMI (kg/m²)		12.09 (1.08)		12.31 (0.96)		11.88 (1.15)	<0.01^c
Nutrition	264		130		134
Dairy consumption (g/week)		1953 (1159)		2048 (1122)		1861 (1190)	0.19^a
Accelerometry	210		105		105
Sedentary time (%)^d		57.7 (7.3)		56.9 (7.6)		58.8 (6.9)	0.09^a
Light PA (%)^d		34.6 (5.5)		34.5 (5.7)		34.5 (5.2)	0.82^a
Moderate PA (%)^d		5.0 (1.9)		5.7 (2)		4.4 (1.5)	<0.01^a
Vigorous PA (%)^d		2.7 (1.8)		2.9 (1.8)		2.4 (1.7)	0.01^c
MVPA (%)^d		7.7 (3.3)		8.7 (3.5)		6.7 (2.9)	<0.01^a

Abbreviations: PEL, Parental education level; DXA, Dual-energy X-ray Absorptiometry; BMC, Bone Mineral Content; BMD, Bone Mineral Density; FMI, fat mass index; FFMI, fat-free mass index; PA, Physical Activity; MVPA, Moderate to Vigorous Physical Activity;^aT-test;^bChi-square test; ^cMann-Whitney U-test; ^d% of recorded time

ISSN: 1471-2458