Associations of Moderate-to-Vigorous Physical Activity with Obesity and Low Muscle Mass Among Postmenopausal Chinese Women: A Cross-Sectional Study

Abstract

Objective

To examine the associations of guideline-based moderate-to-vigorous physical activity (MVPA) levels with obesity and low muscle mass in postmenopausal Chinese women.

Methods

Cross-sectional data from 1578 postmenopausal women aged ≥45 years in Jiangsu, China were analyzed. Obesity was defined as body fat percentage ≥30% according to Chinese criteria, and low muscle mass as appendicular skeletal muscle index <5.7 kg/m² according to the Asian Working Group for Sarcopenia 2019 criteria. Both were assessed using bioelectrical impedance. Physical activity was assessed using the International Physical Activity Questionnaire–Short Form. MVPA was calculated and categorized according to World Health Organization (WHO) physical activity recommendations (<150, 150–299, and ≥300 min/week). Multivariable logistic regression models were used to examine associations between MVPA levels and study outcomes.

Results

27.7% (n=437) of women had obesity and 7.5% (n=118) had low muscle mass. Compared with women reporting <150 min/week of MVPA, those reporting 150–299 min/week and ≥300 min/week had lower odds of obesity. In fully adjusted models, the odds ratios were 0.55 (95% CI: 0.35–0.86) and 0.42 (95% CI: 0.29–0.61), respectively. The corresponding odds ratios for low muscle mass were 0.21 (95% CI: 0.07–0.68) and 0.30 (95% CI: 0.14–0.66).

Conclusion

Higher MVPA was associated with lower odds of obesity. Inverse associations were also observed for low muscle mass, although this finding warrants cautious interpretation.

Plain Language Summary

Menopause is often accompanied by increases in body fat and declines in muscle mass, which may affect later-life health and physical function. Evidence on these outcomes among postmenopausal Chinese women remains limited.

This study examined 1578 postmenopausal women in Jiangsu, China. Women reporting at least 150 min/week of moderate-to-vigorous physical activity (MVPA) were less likely to have obesity than those reporting lower activity levels. Lower odds of low muscle mass were also observed, although relatively few women in the higher MVPA groups had low muscle mass.

These findings show an association between higher MVPA and healthier body composition but do not establish that physical activity directly caused these differences. Further longitudinal research is needed, particularly for low muscle mass.

Introduction

Menopause, marked by the permanent cessation of ovarian function, is accompanied by a pronounced decline in circulating estrogens, particularly estradiol.^1,2 These changes include greater abdominal and visceral adiposity and reductions in lean or skeletal muscle mass, which may contribute to poorer cardiometabolic and functional health in later life.^3,4 These changes may increase susceptibility to obesity and low muscle mass and complicate health management in postmenopausal women.⁵

Obesity during and after menopause is associated with metabolic, cardiovascular, musculoskeletal, and oncological morbidity.⁶ Low muscle mass is a core component of sarcopenia and represents an important health concern in aging women.⁷ A recent meta-analysis estimated the prevalence of sarcopenia at 21.6% among older Chinese women, while a study of Chinese women reported a prevalence of 7.4% among postmenopausal participants.^8,9 Because body size and muscle-mass distribution differ across populations, criteria developed primarily for European populations may not be directly applicable to Asian adults. The Asian Working Group for Sarcopenia (AWGS) therefore provides population-specific thresholds for Asian populations.^10,11 Sarcopenia is associated with functional impairment and reduced health-related quality of life.^12,13 The coexistence of excess adiposity and impaired muscle health may further compromise physical function and metabolic health.¹⁴ Preserving muscle mass and metabolic health is therefore fundamental to healthy aging in women.¹⁵

Physical activity (PA) may help mitigate menopause-related disturbances in adipose metabolism and support cardiovascular health in postmenopausal women.^16,17 Despite growing evidence supporting the benefits of physical activity for body composition in postmenopausal women, current guidelines, including the World Health Organization (WHO) 2020 recommendations, primarily emphasize overall activity levels, while evidence regarding guideline-defined activity levels and body-composition outcomes remains limited.¹⁸ A recent target trial emulation found that moderate and vigorous activity were associated with more favorable body-composition changes in postmenopausal women.¹⁹ However, much of the available evidence has been derived from structured exercise interventions,²⁰ providing limited evidence on whether meeting or exceeding recommended moderate-to-vigorous physical activity (MVPA) levels is associated with obesity and low muscle mass in postmenopausal Chinese women.

Therefore, this study aimed to examine the associations between guideline-based MVPA levels and obesity and low muscle mass in a large community-based sample of postmenopausal Chinese women. We also explored the continuous associations between MVPA and both outcomes using spline models.

Methods

Study Design and Population

This cross-sectional secondary analysis used data from the Jurong Chronic Non-communicable Disease Survey conducted in Jiangsu Province, China, between October 2015 and January 2016. The archived survey data were incorporated into a research database in 2024 and subsequently used for the present analysis. The parent survey recruited 11,151 community-dwelling residents, including 5125 women. Women who were not postmenopausal (n=1614), had undergone hysterectomy (n=222), or were aged <45 years (n=507) were excluded. A further 952 women were excluded because of missing or abnormal bioelectrical impedance analysis (BIA) data. Among the remaining participants, 213 were excluded because of missing or abnormal questionnaire data and 39 were excluded because of current hormone therapy use. The final analytic sample comprised 1578 postmenopausal women (Figure 1).

Figure 1.

Flow diagram of participant selection. The flow diagram shows the sequential inclusion and exclusion of participants from the parent survey to the final analytic sample of 1578 postmenopausal women.

Abbreviation: BIA, bioelectrical impedance analysis.

Eligible participants were women aged ≥45 years who had experienced natural menopause, defined as at least 12 consecutive months of amenorrhea. Women with a history of hysterectomy were excluded because natural menopausal status could not be reliably determined from menstrual history. A complete-case analysis was conducted, and participants with missing data on the exposure, outcomes, or prespecified covariates were excluded.

The establishment and secondary research use of the archived database were approved by the Tsinghua University Science and Technology Ethics Committee in 2024 (Approval No. THU01-20240130). Written informed consent was obtained from all participants at the time of the original survey.

Measures

Basic Information

Trained investigators conducted face-to-face interviews using a standardized questionnaire. Information was collected on demographic characteristics, lifestyle behaviors, chronic diseases, menopausal duration, and regularly used medications. Current hormone therapy use was identified from the reported medication names. Chronic disease status was coded as a binary variable indicating the presence of at least one self-reported chronic disease.

Body Composition

Body composition was assessed using a multi-frequency bioelectrical impedance analyzer (BCA-2A, Tsinghua Tongfang, Beijing, China). Measurements were performed by trained personnel using a standardized protocol. The instrument was calibrated twice daily. Participants removed all metal objects and were measured barefoot while wearing light clothing. They stood quietly on the electrode platform, held the hand electrodes, and kept their arms slightly away from the trunk during measurement.

Participants with cardiac pacemakers or other metal implants, limb disabilities, or communication difficulties that prevented standardized measurement were not assessed. Body-composition assessment and questionnaire administration were completed during the same visit, and each participant was measured once. Body fat percentage and appendicular skeletal muscle mass were recorded. Appendicular skeletal muscle index (ASMI) was calculated as appendicular skeletal muscle mass divided by height squared (kg/m²).

Dietary Assessment

Dietary intake was assessed using an interviewer-administered food frequency questionnaire. The present analysis included six selected protein-rich food groups: eggs, fish and seafood, livestock meat, poultry, milk and dairy products, and soybeans and soy products. Participants reported their usual consumption frequency as times per day, week, month, or year, together with the amount consumed on each occasion. Egg intake was converted to weight assuming that one egg was equivalent to one liang (50 g), while the amounts of the other foods were recorded in liang (1 liang = 50 g). Consumption frequencies were converted to weekly equivalents and multiplied by the amount consumed on each occasion. Weekly intakes of the six food groups were summed to derive the combined intake of selected protein-rich foods (g/week), which was included as a covariate.

Diagnostic Criteria

Obesity

Obesity was defined as whole-body fat percentage ≥30%, consistent with the 2024 Chinese guidelines for adult women.²¹

Low Muscle Mass

Low muscle mass was defined as appendicular skeletal muscle index (ASMI) < 5.7 kg/m², according to the bioelectrical impedance-based cut-off point for women established by the AWGS in 2019.¹¹

Physical Activity Assessment

PA over the preceding seven days was assessed using the Chinese version of the International Physical Activity Questionnaire-Short Form (IPAQ-SF), which has been validated in this population.²² Trained investigators administered the questionnaire through face-to-face interviews. Following the official IPAQ scoring protocol, total minutes per week were calculated for three intensity levels: walking, moderate-intensity PA (MPA), and vigorous-intensity PA (VPA). Participants were excluded if the total reported daily time in activities exceeded 960 min/day, in accordance with the IPAQ data-processing protocol.²³

Weekly MPA and VPA minutes were calculated from the reported frequency and duration. MVPA was calculated as MPA minutes plus twice the VPA minutes (MVPA = MPA + 2 × VPA). Participants were categorized as reporting <150, 150–299, or ≥300 min/week of MVPA according to the WHO recommendations.¹⁸

Statistical Analysis

Continuous variables were assessed for distributional characteristics and are presented as mean ± standard deviation (SD) or median with interquartile range (IQR), as appropriate. Differences across MVPA categories were evaluated using one-way analysis of variance for approximately normally distributed variables and the Kruskal–Wallis test for skewed variables. Categorical variables were compared using the chi-square test or Fisher’s exact test when expected cell counts were small. Multivariable logistic regression models were used to examine the associations between MVPA categories and the presence of obesity and low muscle mass. Three models were constructed: Model 1 (crude), Model 2 adjusted for age, menopausal duration, and education level, and Model 3 further adjusted for smoking status, alcohol consumption, chronic disease status, and protein-rich food intake. Results are presented as odds ratios (ORs) with 95% confidence intervals (CIs). To further explore the continuous associations between MVPA and the study outcomes, multivariable logistic regression models incorporating a B-spline term with four degrees of freedom were fitted.

All analyses were conducted using R software (version 4.3.3; R Foundation for Statistical Computing, Vienna, Austria). A two-sided P-value < 0.05 was considered statistically significant.

Results

Participant Characteristics

A total of 1578 postmenopausal women were included in the analysis. According to weekly MVPA levels, 1166 participants reported <150 min/week, 148 reported 150–299 min/week, and 264 reported ≥300 min/week of moderate-to-vigorous physical activity.

Participant characteristics according to MVPA category are presented in Table 1. Mean age and menopausal duration were lower across progressively higher MVPA categories (both P<0.001). Education level and protein-rich food intake also differed across MVPA categories (both P<0.001), whereas BMI and body fat percentage did not differ significantly (P=0.235 and P=0.650, respectively). ASMI differed slightly across groups (P=0.031). Differences were also observed in alcohol use and chronic disease prevalence (P=0.003 and P<0.001, respectively), whereas current smoking status did not differ across groups (P=0.431). All participants were Han Chinese.

Table 1.

Participant Characteristics According to Levels of Moderate-to-Vigorous Physical Activity (MVPA)

Variable	<150 Min/Week (n=1166)	150–299 Min/Week (n=148)	≥300 Min/Week (n=264)	P value
Age (years)	64.28 ± 7.82	61.71 ± 7.46	60.48 ± 7.12	<0.001
Ethnicity, n (%)				—
Han Chinese	1166 (100.0%)	148 (100.0%)	264 (100.0%)
Menopausal duration (years)	15.13 ± 9.32	12.80 ± 8.57	10.88 ± 9.04	<0.001
Education level, n (%)				<0.001
No formal education	615 (52.7%)	67 (45.3%)	91 (34.5%)
Primary school not completed	207 (17.8%)	18 (12.2%)	39 (14.8%)
Primary school completed	139 (11.9%)	18 (12.2%)	32 (12.1%)
Junior secondary school completed	160 (13.7%)	36 (24.3%)	71 (26.9%)
Senior secondary or technical secondary school completed	45 (3.9%)	9 (6.1%)	30 (11.4%)
College diploma or bachelor’s degree	0 (0.0%)	0 (0.0%)	1 (0.4%)
Protein-rich food intake (g/week)	964.17 (558.96–1525.62)	1050.00 (671.80–1947.50)	1155.75 (719.23–1849.58)	<0.001
BMI (kg/m2)	24.95 ± 3.66	25.28 ± 3.03	25.29 ± 2.91	0.235
Body fat percentage (%)	33.94 ± 5.37	34.25 ± 5.18	34.22 ± 6.10	0.650
ASMI (kg/m2)	7.59 ± 2.13	7.95 ± 1.44	7.83 ± 0.99	0.031
Current smoker, n (%)	23 (2.0%)	2 (1.4%)	2 (0.8%)	0.431
Alcohol use, n (%)	103 (8.8%)	26 (17.6%)	30 (11.4%)	0.003
Chronic disease, n (%)	919 (78.8%)	130 (87.8%)	235 (89.0%)	<0.001
Obesity, n (%)	374 (32.1%)	27 (18.2%)	36 (13.6%)	<0.001
Low muscle mass, n (%)	108 (9.3%)	3 (2.0%)	7 (2.7%)	<0.001

Notes: Values are presented as mean ± standard deviation (SD) for approximately normally distributed continuous variables, median (interquartile range, IQR) for protein-rich food intake, and number (percentage) for categorical variables. Differences across MVPA categories were evaluated using one-way analysis of variance, the Kruskal–Wallis test, the chi-square test, or Fisher’s exact test, as appropriate. No P value was calculated for ethnicity because all participants were Han Chinese.

Abbreviations: ASMI, appendicular skeletal muscle index; BMI, body mass index; IQR, interquartile range; MVPA, moderate-to-vigorous physical activity; SD, standard deviation.

The prevalence of obesity was 32.1% among women reporting <150 min/week of MVPA, 18.2% among those reporting 150–299 min/week, and 13.6% among those reporting ≥300 min/week. The corresponding prevalence of low muscle mass was 9.3%, 2.0%, and 2.7%, respectively. Both outcomes differed across MVPA categories (both P<0.001).

Associations of MVPA Categories with Obesity and Low Muscle Mass

The association was more consistent for obesity than for low muscle mass, with lower obesity odds among women meeting or exceeding the guideline-recommended 150 min/week of MVPA (Figure 2A). For low muscle mass, the curve was non-monotonic and less precise at higher MVPA levels (Figure 2B).

Figure 2.

Spline-based associations of moderate-to-vigorous physical activity with obesity and low muscle mass. (A) Obesity; (B) low muscle mass. Solid lines represent adjusted odds ratios and shaded areas represent 95% confidence intervals. The horizontal and vertical dashed lines indicate OR=1.0 and 150 min/week of MVPA, respectively. Models were adjusted for age, menopausal duration, education level, smoking status, alcohol consumption, chronic disease status, and protein-rich food intake.

Results from the multivariable logistic regression analyses are presented in Table 2. Compared with women reporting <150 min/week of MVPA, those reporting 150–299 min/week had lower odds of obesity (OR = 0.55, 95% CI: 0.35–0.86). Women reporting ≥300 min/week also had lower odds (OR = 0.42, 95% CI: 0.29–0.61).

Table 2.

Associations of MVPA Categories with Obesity and Low Muscle Mass

Outcome	MVPA Category	Model 1 OR (95% CI)	Model 2 OR (95% CI)	Model 3 OR (95% CI)
Obesity	<150 min/week	1.00 (Reference)
	150–299 min/week	0.47 (0.31–0.73)	0.52 (0.34–0.81)	0.55 (0.35–0.86)
	≥300 min/week	0.33 (0.23–0.49)	0.40 (0.27–0.58)	0.42 (0.29–0.61)
Low muscle mass	<150 min/week	1.00 (Reference)
	150–299 min/week	0.20 (0.06–0.65)	0.23 (0.07–0.72)	0.21 (0.07–0.68)
	≥300 min/week	0.27 (0.12–0.58)	0.32 (0.14–0.69)	0.30 (0.14–0.66)

Notes: Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression models. Model 1 was unadjusted. Model 2 was adjusted for age, menopausal duration, and education level. Model 3 was further adjusted for smoking status, alcohol consumption, chronic disease status, and protein-rich food intake.

Abbreviations: CI, confidence interval; MVPA, moderate-to-vigorous physical activity; OR, odds ratio.

For low muscle mass, women reporting 150–299 min/week had lower odds compared with those reporting <150 min/week (OR = 0.21, 95% CI: 0.07–0.68). Women reporting ≥300 min/week also had lower odds (OR = 0.30, 95% CI: 0.14–0.66).

Discussion

This study examined the associations between PA levels and body composition outcomes in postmenopausal Chinese women. Higher levels of MVPA were associated with lower odds of obesity, while an inverse association was also observed for low muscle mass. The association appeared more consistent for obesity than for low muscle mass. In the spline analysis, the adjusted odds of obesity generally decreased with increasing MVPA, whereas the low-muscle-mass curve was less stable. These findings suggest that regular physical activity may play an important role in maintaining healthier body composition during the postmenopausal period.

The observed association with obesity is biologically plausible because the menopausal transition is accompanied by greater abdominal adiposity and adverse cardiometabolic changes.^3,4 Exercise training can reduce fat mass, body fat percentage, waist circumference, and visceral fat in postmenopausal women.²⁴ It also improves several cardiometabolic risk factors.²⁵ The spline analysis showed a generally inverse association between MVPA and obesity, with lower odds observed among women meeting or exceeding 150 min/week. This pattern is broadly consistent with current public health recommendations and with previous evidence linking moderate levels of physical activity to favorable body-composition outcomes in postmenopausal women.²⁶ In particular, prior research suggests that these favorable changes are most apparent at activity levels corresponding to at least 150 minutes of moderate-intensity activity per week.¹⁹

The association between MVPA and low muscle mass was less consistent. The non-monotonic spline curve and wide confidence intervals at higher MVPA levels further support cautious interpretation of this association. Mechanical loading, particularly through resistance-based activity, may help preserve muscle strength and mass.²⁴ Resistance exercise and postexercise protein ingestion may influence the temporal pattern of myofibrillar protein synthesis in postmenopausal women.²⁷ A recent systematic review confirmed the benefits of resistance training for physical fitness and strength in postmenopausal women, although its effects on body-composition measures were less consistent.²⁸ In the present study, the prevalence of low muscle mass did not decline monotonically across MVPA categories. Nevertheless, the overall pattern is broadly consistent with evidence showing that higher levels of total physical activity and MVPA are associated with lower odds of sarcopenia in older adults.²⁹ However, because the IPAQ-SF did not distinguish specific activity types, the observed association cannot be attributed specifically to resistance exercise.

Dietary and health-related factors may also have contributed to the observed associations. Protein-rich food intake differed across MVPA categories. Because dietary protein may support muscle maintenance, this factor was included in the fully adjusted models.³⁰ The association between MVPA and low muscle mass remained after adjustment, suggesting that it was not fully explained by the measured dietary intake. Chronic disease was more prevalent in the higher-MVPA groups, possibly because some women increased their physical activity after diagnosis.

From a practical perspective, the findings support encouraging postmenopausal women to achieve guideline-recommended MVPA and incorporate muscle-strengthening activities where appropriate. Nevertheless, several limitations should be considered. The cross-sectional design precludes causal inference and cannot exclude reverse causation. Physical activity was assessed using the IPAQ-SF, which relies on seven-day recall, may overestimate activity, may not capture habitual or seasonal activity patterns, and does not distinguish specific activity types. The small number of low-muscle-mass cases in the higher-MVPA groups also reduced the precision of these estimates. In addition, previous hormone therapy use and menopausal symptoms were not assessed. Finally, the participants were Han Chinese women from Jiangsu Province, which may limit generalizability to women in other regions of China, particularly rural populations, and to other Asian populations.

Conclusion

Among postmenopausal Chinese women, higher MVPA was associated with lower odds of obesity. Inverse associations were also observed for low muscle mass, although these findings should be interpreted cautiously because of the small number of cases in the higher-MVPA groups. These cross-sectional findings are consistent with current recommendations to promote MVPA, but prospective studies are needed to confirm the direction of the associations and clarify their implications for muscle health.

Funding Statement

This research was funded by the National Population Health Data Center of China, grant number NCMI202307GEN.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki, and was approved by the Institutional Review Board of Tsinghua University [Approval Number: THU01-20240130].

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare no conflicts of interest in this work.