Association Between Parental Socioeconomic Status and Skeletal Muscle Mass in Chinese College Students: Fitness Improvement Tactics in Youths (FITYou) Project

Figures & data

Figure 1 Participants’ selection flowchart.

Table 1 Participants’ Characteristics According to Parental SES Scores in Chinese College Freshmen (n=2204)

Variable^a	Tertiles of Total Parental SES Scores
	Low	Middle	High	p value^b
Participants, no. (%)	712 (32.3)	739 (33.5)	753 (34.2)
Sex (female), no. (%)	556 (78.1)	562 (76.0)	549 (72.9)	0.066
Age (years)	18.7 (1.4)	18.5 (1.4)	18.3 (1.2)	<0.001
Han ethnicity, no. (%)	592 (83.1)	627 (84.8)	628 (83.4)	0.635
BMI (kg/m^2)	21.7 (3.8)	21.6 (3.8)	21.8 (4.0)	0.519
Smoking status
Never, no. (%)	685 (96.2)	711 (96.2)	720 (95.6)
Former, no. (%)	11 (1.5)	17 (2.3)	13 (1.7)
Current, no. (%)	16 (2.2)	11 (1.5)	20 (2.7)	0.450
Alcohol use (yes), no. (%)	70 (9.8)	107 (14.5)	106 (14.1)	0.016
Sleep duration (hours/day)
<6, no. (%)	145 (20.4)	155 (21.0)	181 (24.0)
6–7, no. (%)	280 (39.3)	279 (37.8)	279 (37.1)
7–8, no. (%)	239 (33.6)	250 (33.8)	226 (30.0)
≥8, no. (%)	48 (6.7)	55 (7.4)	67 (8.9)	0.273
Paternal educational status
Primary school, no. (%)	182 (25.6)	64 (8.7)	6 (0.8)
Middle school, no. (%)	422 (59.3)	316 (42.8)	93 (12.4)
High school, no. (%)	89 (12.5)	247 (33.4)	179 (23.8)
≥ College, no. (%)	19 (2.7)	112 (15.2)	475 (63.1)	<0.001
Paternal annual income (CNY)
<15,000, no. (%)	531 (74.6)	235 (31.8)	74 (9.8)
15,000–29,999, no. (%)	129 (18.1)	146 (19.8)	33 (4.4)
30,000–49,999, no. (%)	40 (5.6)	187 (25.3)	193 (25.6)
≥ 50,000, no. (%)	12 (1.7)	171 (23.1)	453 (60.2)	<0.001
Paternal occupational status
Non-employed, no. (%)	169 (23.7)	76 (10.3)	30 (4.0)
Self-employed, no. (%)	115 (16.2)	131 (17.7)	73 (9.7)
Blue collar worker, no. (%)	422 (59.3)	470 (63.6)	288 (38.2)
White collar worker, no. (%)	6 (0.8)	62 (8.4)	362 (48.1)	<0.001
Maternal educational status
Primary school, no. (%)	229 (32.2)	81 (11.0)	3 (0.4)
Middle school, no. (%)	390 (54.8)	351 (47.5)	103 (13.7)
High school, no. (%)	78 (11.0)	203 (27.5)	191 (25.4)
≥ College, no. (%)	15 (2.1)	104 (14.1)	456 (60.6)	<0.001
Maternal annual income (CNY)
<15,000, no. (%)	631 (88.6)	362 (49.0)	93 (12.4)
15,000–29,999, no. (%)	67 (9.4)	173 (23.4)	79 (10.5)
30,000–49,999, no. (%)	12 (1.7)	137 (18.5)	233 (30.9)
≥ 50,000, no. (%)	2 (0.3)	67 (9.1)	348 (46.2)	<0.001
Maternal occupational status
Non-employed, no. (%)	228 (32.0)	118 (16.0)	38 (5.0)
Self-employed, no. (%)	117 (16.4)	156 (21.1)	134 (17.8)
Blue collar worker, no. (%)	365 (51.3)	433 (58.6)	295 (39.2)
White collar worker, no. (%)	2 (0.3)	32 (4.3)	286 (38.0)	<0.001

Notes: ^aCategorized variables were presented as number and percentages, and continuous variables were presented as means (standard deviations). ^bAnalysis of variance or χ² test, as appropriate.

Abbreviations: BMI, body mass index; CNY, Chinese Yuan; SES, socioeconomic status.

Table 2 Association Between Total Parental SES Scores and Skeletal Muscle Mass in Chinese College Freshmen (n=2204)

	Tertiles of Total Parental SES Scores
	Low (n=712)	Middle (n=739)	High (n=753)	p value ^a
Skeletal muscle mass (kg)
Non-adjusted model	42.0 (41.3, 42.6)	42.9 (42.3, 43.5)	44.2 (43.6, 44.8)	<0.001
Adjusted model 1^b	42.4 (42.0, 42.8)	43.0 (42.6, 43.3)	43.7 (43.4, 44.1)	<0.001
Adjusted model 2^c	42.4 (42.0, 42.8)	42.9 (42.6, 43.3)	43.7 (43.4, 44.1)	<0.001
Skeletal muscle mass (kg)/height^2 (m^2)
Non-adjusted model	15.4 (15.3, 15.6)	15.4 (15.3, 15.6)	15.5 (15.4, 15.7)	0.269
Adjusted model 1^b	15.5 (15.4, 15.6)	15.4 (15.3, 15.5)	15.4 (15.3, 15.5)	0.461
Adjusted model 2^c	15.5 (15.4, 15.6)	15.4 (15.3, 15.5)	15.4 (15.3, 15.5)	0.417
Skeletal muscle mass (kg)/weight (kg)
Non-adjusted model	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.949
Adjusted model 1 ^b	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.385
Adjusted model 2^c	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.377
Skeletal muscle mass (kg)/BMI (kg/m^2)
Non-adjusted model	1.96 (1.94, 1.99)	2.01 (1.98, 2.03)	2.05 (2.03, 2.08)	<0.001
Adjusted model 1^b	1.98 (1.96, 1.99)	2.01 (1.99, 2.03)	2.03 (2.02, 2.05)	<0.001
Adjusted model 2^c	1.98 (1.96, 1.99)	2.01 (1.99, 2.03)	2.03 (2.02, 2.05)	<0.001

Notes: ^ap for linear trend was obtained by using analysis of covariance, and data were shown as mean and 95% confidence interval. ^bAdjusted for age (continuous variable), sex (male, female), and ethnicity (Han ethnicity, others). ^cAdjusted for model 1 plus smoking status (current smoker, former smoker, never smoker), alcohol use (yes, no), and daily sleep duration (<6, 6–7, 7–8, ≥8 hours).

Abbreviations: BMI, body mass index; SES, socioeconomic status.

Table 3 Association Between Total Paternal and Maternal SES Scores and Skeletal Muscle Mass in Chinese College Freshmen (n=2204)

	Tertiles of Paternal SES Scores				Tertiles of Maternal SES Scores
	Low (n=701)	Middle (n=690)	High (n=813)	p value ^a	Low (n=966)	Middle (n=611)	High (n=627)	p value ^a
Skeletal muscle mass, kg
Non-adjusted model	42.2 (41.5, 42.8)	42.5 (41.8, 43.1)	44.3 (43.7, 44.9)	<0.001	42.0 (41.5, 42.6)	43.1 (42.4, 43.7)	44.6 (43.9, 45.2)	<0.001
Adjusted model 1^b	42.4 (42.0, 42.8)	43.1 (42.7, 43.5)	43.6 (43.2, 44.0)	<0.001	42.5 (42.2, 42.8)	43.0 (42.6, 43.4)	44.0 (43.5, 44.4)	<0.001
Adjusted model 2^c	42.4 (42.0, 42.8)	43.1 (42.7, 43.5)	43.6 (43.2, 44.0)	<0.001	42.5 (42.2, 42.8)	43.0 (42.5, 43.4)	44.0 (43.5, 44.4)	<0.001
Adjusted model 3^d	42.7 (42.4, 43.1)	43.1 (42.8, 43.5)	43.2 (42.9, 43.6)	0.077	42.6 (42.3, 42.9)	43.1 (42.8, 43.4)	43.7 (43.3, 44.1)	<0.001
Skeletal muscle mass (kg)/height^2 (m^2)
Non-adjusted model	15.4 (15.3, 15.6)	15.4 (15.2, 15.5)	15.6 (15.4, 15.7)	0.155	15.4 (15.3, 15.5)	15.4 (15.2, 15.5)	15.6 (15.5, 15.8)	0.016
Adjusted model 1^b	15.5 (15.4, 15.6)	15.5 (15.4, 15.6)	15.4 (15.3, 15.5)	0.772	15.5 (15.4, 15.6)	15.4 (15.2, 15.5)	15.5 (15.4, 15.6)	0.549
Adjusted model 2^c	15.5 (15.4, 15.6)	15.5 (15.4, 15.6)	15.4 (15.3, 15.5)	0.757	15.5 (15.4, 15.6)	15.4 (15.3, 15.5)	15.5 (15.4, 15.6)	0.563
Adjusted model 3^d	15.5 (15.4, 15.6)	15.5 (15.4, 15.6)	15.4 (15.3, 15.5)	0.448	15.5 (15.3, 15.6)	15.4 (15.3, 15.5)	15.5 (15.3, 15.8)	0.679
Skeletal muscle mass (kg)/weight (kg)
Non-adjusted model	0.73 (0.72, 0.73)	0.72 (0.71, 0.73)	0.72 (0.72, 0.73)	0.510	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.955
Adjusted model 1^b	0.73 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.71, 0.72)	0.096	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.71, 0.73)	0.236
Adjusted model 2^c	0.73 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.71, 0.72)	0.097	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.71, 0.73)	0.234
Adjusted model 3^d	0.73 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.71, 0.73)	0.188	0.72 (0.72, 0.73)	0.72 (0.72, 0.73)	0.72 (0.71, 0.73)	0.630
Skeletal muscle mass (kg)/BMI (kg/m^2)
Non-adjusted model	1.98 (1.95, 2.00)	1.99 (1.96, 2.01)	2.05 (2.03, 2.07)	<0.001	1.97 (1.95, 1.99)	2.02 (1.99, 2.05)	2.05 (2.02, 2.08)	<0.001
Adjusted model 1^b	1.98 (1.97, 2.00)	2.00 (1.99, 2.03)	2.03 (2.01, 2.04)	0.001	1.98 (1.97, 2.00)	2.02 (2.00, 2.04)	2.03 (2.01, 2.05)	<0.001
Adjusted model 2^c	1.98 (1.97, 2.00)	2.01 (1.99, 2.03)	2.03 (2.01, 2.04)	0.001	1.98 (1.97, 2.00)	2.02 (2.00, 2.04)	2.03 (2.01, 2.05)	<0.001
Adjusted model 3^d	1.99 (1.97, 2.02)	2.01 (1.99, 2.03)	2.01 (1.99, 2.04)	0.225	1.98 (1.96, 2.01)	2.02 (2.00, 2.04)	2.03 (1.99, 2.07)	0.177

Notes: ^ap for linear trend was obtained by using analysis of covariance, and data were shown as mean and 95% confidence interval. ^bAdjusted for age (continuous variable), sex (male, female), and ethnicity (Han ethnicity, others). ^cAdjusted for model 1 plus smoking status (current smoker, former smoker, never smoker), alcohol use (yes, no), and daily sleep duration (<6, 6–7, 7–8, ≥8 hours). ^dAdjusted for model 2 plus paternal or maternal SES (continuous variable), as appropriate.

Abbreviations: BMI, body mass index; SES, socioeconomic status.

Figure 2 Association of paternal and maternal socioeconomic status with skeletal muscle mass in Chinese college freshmen. Analysis of covariance was performed by adjusting for age (continuous variable), sex (male, female), ethnicity (Han ethnicity, others), smoking status (current smoker, former smoker, never smoker), alcohol use (yes, no), and daily sleep duration (<6, 6–7, 7–8, ≥8 hours). Data are presented as mean and 95% confidence interval.

Figure 3 Association of paternal and maternal socioeconomic status with skeletal muscle mass adjusted by BMI in Chinese college freshmen. Analysis of covariance was performed by adjusting for age (continuous variable), sex (male, female), ethnicity (Han ethnicity, others), smoking status (current smoker, former smoker, never smoker), alcohol use (yes, no), and daily sleep duration (<6, 6–7, 7–8, ≥8 hours). Data are presented as mean and 95% confidence interval. BMI, body mass index.