Introduction

Metabolic syndrome (MetS) is characterized by a cluster of interrelated metabolic abnormalities that markedly increase the risk of cardiovascular disease and type 2 diabetes1. Diagnostic criteria typically include abdominal obesity, dyslipidemia, hypertension, and insulin resistance2. The global prevalence of MetS has risen sharply in parallel with escalating sedentary lifestyles and obesity rates3. In China, its age-adjusted prevalence now exceeds 24%, posing a major public health challenge4.

University faculty are particularly vulnerable to metabolic disorders owing to prolonged sedentary occupational patterns, psychological stress, and time constraints that limit opportunities for physical activity5. Importantly, sedentary behavior at work has been shown to independently contribute to MetS risk, even after accounting for leisure-time physical activity6. Female academics may face compounded risks during perimenopause, as hormonal fluctuations exacerbate abdominal adiposity and metabolic dysfunction7.

Our findings are consistent with a growing body of evidence supporting the efficacy of various exercise modalities for improving metabolic health. Recent studies have highlighted that concurrent training can elicit comprehensive improvements in body composition and cardiometabolic risk factors8,9. Similarly, aerobic and high-intensity interval training (HIIT) have demonstrated potent effects on enhancing metabolic profiles and reducing cardiovascular risk in individuals with metabolic dysregulation10,11. Furthermore, resistance training is recognized as a cornerstone therapy for increasing lean mass and improving insulin sensitivity, which is particularly crucial for populations with metabolic syndrome or type 2 diabetes12,13. These findings, along with evidence from tailored interventions in specific populations14,15, underscore the broad applicability of exercise and suggest that optimized programs can yield significant health benefits. Our study extends this literature by evaluating the effects of a combined aerobic and resistance training program within a specific, high-risk occupational group that has been understudied.

Despite this evidence, the specific efficacy of combined exercise programs in high-risk occupational groups, such as perimenopausal female academics, remains insufficiently studied. The present study evaluated the effects of a 12-week combined aerobic and resistance training program on physical fitness, lipid metabolism, and MetS components in Chinese female university teachers. We hypothesized that the intervention would significantly improve lipid profiles (particularly triglycerides and cholesterol), MetS-related indices, and fitness outcomes, with differential responses depending on baseline metabolic status.

Methods

Ethical approval

This study was approved by the Biomedical Ethics Committee of Hebei University of Engineering Medical College [Approval No.: 2023[K]030-20], and data were processed after obtaining permission from the China Clinical Trial Registry (ChiCTR). The research process strictly adhered to international ethical standards and followed the principles stipulated in the Declaration of Helsinki.

Participants

Sample size was calculated using G*Power, based on prior findings of ~ 10% improvement in HDL-C16, yielding a minimum requirement of 90 participants (f = 0.25, α = 0.05, β = 0.8). A total of 120 eligible female university teachers were screened. Following exclusion of 19 high-risk individuals according to the American College of Sports Medicine (ACSM) pre-participation guidelines17, 101 perimenopausal women (aged 43–49 years) were enrolled.

Participants were stratified according to International Diabetes Federation criteria1:

  • Asymptomatic (n = 19): No metabolic abnormalities.

  • Metabolic syndrome (MetS) (n = 50): Presence of 2–3 MetS components.

Metabolic disease (n = 32): Presence of ≥ 4 MetS components or diagnosed type 2 diabetes (T2D), hypertension, or dyslipidemia requiring stable pharmacological treatment treatment for ≥ 3 months.

*Note:* The “Metabolic Disease” group included participants with clinically diagnosed disorders aligning with MetS components (e.g., T2D, hypertension, or dyslipidemia) under stable medication for ≥ 3 months. These conditions were defined as “related disorders” due to their direct pathophysiological link to MetS. Medication regimens remained unchanged during the study to minimize confounding effects.

Exclusion criteria were: (1) cardiovascular, renal, or hepatic disease; (2) current use of medications influencing metabolic parameters; (3) pregnancy or lactation; and (4) inability to adhere to the exercise program.

Exercise intervention

The supervised 12-week program consisted of three 60-min sessions per week, with progressive increases in intensity. Each session included a 10-min warm-up, the main exercise component, and a cooldown with dynamic and static stretching. Aerobic activity comprised moderate-intensity brisk walking, while resistance training incorporated progressive core and lower-limb exercises. Polar heart rate monitors were used to maintain target intensities, and certified fitness instructors supervised all sessions to ensure correct technique and adherence. Attendance exceeded 90% across participants (Table 1).

Table 1 12-week progressive exercise program design (HRR: Heart Rate Reserve).
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Measurements

Trained staff conducted all baseline and post-intervention assessments. To minimize bias, the outcome assessors who performed these measurements were blinded to the participants’ baseline metabolic classification (asymptomatic, MetS, or metabolic disease) throughout the data collection and analysis phases. The assessments included:

  1. 1.

    Health-related fitness:

  2. •

    Muscular strength: Handgrip (T.K.K. 5401 Dynamometer, Takei, Japan)

  3. •

    Muscular endurance: 1-min sit-up test

  4. •

    Flexibility: Sit-and-reach (T.K.K. 5413 Box, Takei, Japan)

  5. •

    Cardiorespiratory endurance: 6-min walk test (ST-200 Spirometer, Kangyu, China)

  6. •

    Body composition: InBody 770 bioelectrical impedance analyzer (InBody, South Korea)

  7. 2.

    Blood pressure: Triplicate seated measurements after 10 min of rest (Omron HEM-7130, Japan)

  8. 3.

    Biochemical analysis: After a 12-h fast, venous blood was drawn and analyzed for total cholesterol, HDL-C, LDL-C, triglycerides (TG), and glucose using enzymatic colorimetric methods (Mindray BS-800, China).

Statistical analysis

Data were analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY). Normality was assessed with the Shapiro–Wilk test. For normally distributed variables, paired t-tests compared pre- and post-intervention data within groups; for non-normal data, Wilcoxon signed-rank tests were applied. Frequency analysis was used to evaluate changes in MetS classification. Results are reported as mean ± standard deviation (SD). Statistical significance was set at p < 0.05. Effect sizes were calculated using Cohen’s d.

Results

Participant characteristics

All 101 participants completed the intervention, yielding a 100% retention rate. The intervention was well-tolerated by all participants.At baseline, no significant differences were observed between groups apart from the metabolic parameters that defined classification (Table 2). The metabolic disease group exhibited significantly higher baseline BMI, blood pressure, fasting glucose, and triglyceride levels (p < 0.01).

Table 2 Baseline characteristics of study participants (*p < 0.05 vs asymptomatic; †p < 0.05 vs MetS).
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Physical fitness improvements

Significant improvements were observed in all fitness parameters following the 12-week intervention (Table 3). The metabolic disease group achieved the largest gains in muscular strength (+ 9.5%, Cohen’s d = 0.477) and muscular endurance (+ 35.4%, Cohen’s d = 1.770), with the endurance parameter demonstrating a large effect size. Flexibility and cardiorespiratory endurance improved across all groups (p < 0.001).

Table 3 Changes in health-related physical fitness parameters.
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Lipid and metabolic parameters

Systolic blood pressure decreased significantly (132 ± 11 to 128 ± 10 mmHg, p < 0.001). Improvements in lipid and metabolic indices are summarized in Table 4. Total cholesterol declined significantly in the metabolic disease group (− 4.6%, p < 0.01, Cohen’s d = − 0.228). Triglycerides decreased in both the MetS (− 9.3%, p < 0.05, Cohen’s d = − 0.467) and metabolic disease groups (− 10.0%, p < 0.05, Cohen’s d = − 0.498). Fasting glucose levels declined significantly across all groups (p < 0.001), with the largest reduction observed in participants with metabolic disease.For the entire cohort (n = 101), fasting glucose decreased significantly from 5.37 ± 0.54 to 5.09 ± 0.48 mmol/L (p < 0.001), representing an overall reduction of 5.2%.

Table 4 Changes in blood lipid profile and metabolic parameters.
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Most notably, triglyceride concentrations were significantly reduced in both the MetS group (− 9.3%, p < 0.05) and the metabolic disease group (− 10.0%, p < 0.05).

Changes in metabolic syndrome classification

The intervention resulted in substantial shifts in metabolic classification (Table 5). The prevalence of metabolic disease decreased by 18.8% (from 31.7 to 12.9%), while the proportion of asymptomatic participants increased by 17.8% (from 18.8 to 36.6%). These findings suggest a meaningful reversal of metabolic dysfunction in a clinically significant proportion of participants.

Table 5 Changes in metabolic syndrome classification status.
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Sensitivity analysis

To address potential confounding from pharmacological treatments, a post hoc sensitivity analysis was conducted using MetS component count (0, 1–3, ≥ 4) as an alternative grouping method. This reclassification excluded participants with diagnosed disorders but < 4 MetS criteria (n = 5). Results demonstrated consistent trends:

  • Triglycerides decreased by 9.1% in the 1–3 component group (p < 0.05) and 10.2% in the ≥ 4 component group (p < 0.05).

  • MetS prevalence reduced by 16.5% (from 49.5% to 33.0%).

  • These findings corroborate the primary analysis, supporting the robustness of the intervention effect. (Full data in Supplementary Table S1).

Discussion

This study demonstrates that a 12-week combined aerobic and resistance training program significantly improved health-related fitness, lipid metabolism, and metabolic syndrome (MetS) components in female university teachers. These findings corroborate prior evidence of exercise benefits on metabolic health18,19, while extending existing knowledge by focusing on a high-risk occupational group within the Chinese context.

The differential responses across subgroups suggest a dose–response relationship, wherein individuals with greater baseline impairment achieved larger benefits. This is consistent with the principle of training adaptation, which predicts greater improvements among less fit individuals20. Physiologically, this may be attributed to two complementary mechanisms. First, individuals with more severe baseline insulin resistance have a higher ceiling for improvement; thus, exercise-induced enhancements in muscle glucose uptake via GLUT-4 translocation and improved insulin signaling are more pronounced21. Second, participants with metabolic disease often present with lower baseline muscle mass; they may exhibit a more robust hypertrophic and neuromuscular response to the resistance training component of the intervention, leading to greater gains in strength and a subsequent increase in metabolic capacity22.The marked gains in the metabolic disease group (strength + 9.5%; endurance + 35.4%) highlight the responsiveness of this population, even over a relatively short intervention period.

The reductions in triglycerides (− 9.3% in MetS, − 10.0% in metabolic disease) likely reflect enhanced lipoprotein lipase activity, while the non-significant trend toward increased HDL-C may require a longer intervention period to reach statistical significance, as suggested in prior studies16,23. The selective decrease in total cholesterol in the metabolic disease group (p < 0.01) further indicates that combined training may be particularly effective for individuals with dyslipidemia, consistent with meta-analyses showing superior lipid benefits of combined versus single-modality exercise16.

The consistent reduction in fasting glucose across all groups (p < 0.001) underscores the intervention’s role in improving glycemic control, likely mediated by enhanced skeletal muscle glucose uptake via GLUT-4 translocation and improved insulin signaling21. Importantly, improvements in the asymptomatic group highlight the preventive potential of structured exercise, reinforcing its role in both treatment and primary prevention.

One of the most clinically relevant findings is the reclassification of metabolic status: an 18.8% reduction in metabolic disease prevalence and a 17.5% increase in asymptomatic status. These shifts suggest partial reversal of metabolic dysfunction and mirror outcomes of longer-term lifestyle interventions24,25, but achieved here within a shorter timeframe and a real-world occupational setting.

The synergy of aerobic and resistance training may explain these results. Aerobic exercise primarily enhances lipid metabolism, while resistance training increases muscle mass and basal metabolic rate, collectively promoting lipid oxidation and improving body composition22.

Several clinical implications emerge. First, the differential subgroup responses support tailoring exercise prescriptions to baseline metabolic status, with those at higher risk potentially deriving the greatest benefit. Second, the significant improvements in the metabolic disease group suggest that metabolic dysfunction is at least partially reversible in middle-aged women. Third, implementing structured workplace exercise programs could be a practical strategy to mitigate MetS among academic professionals, for whom time constraints are a key barrier to regular exercise.

In summary, the observed 17.5% rise in asymptomatic cases and 18.8% reduction in metabolic disease prevalence represent meaningful clinical improvements, corresponding to the reduction of approximately 1.5 MetS components per participant who transitioned. These results indicate that structured, combined exercise interventions may accelerate metabolic improvements, offering both preventive and therapeutic benefits in high-risk occupational populations.

Limitations and future directions

Several limitations should be acknowledged. First, the absence of a control group limits the ability to attribute all observed changes exclusively to the exercise intervention, although the magnitude, specificity, and temporal patterns of improvement strongly support an intervention effect26. Second, dietary intake was neither controlled nor monitored, which may have influenced metabolic outcomes25. Third, the relatively short 12-week follow-up precludes conclusions regarding long-term sustainability, though previous studies suggest that continued exercise can maintain metabolic benefits27.Fourth, the inclusion of participants with stable pharmacological treatments for metabolic disorders could introduce confounding effects. However, these participants were included to reflect real-world clinical management. While medications may influence baseline metabolic status, the 3-month stability requirement minimized confounding effects on intervention outcomes.

Future studies should:

  • Employ randomized controlled designs with extended follow-up periods.

  • Incorporate advanced lipid profiling (e.g., LDL particle size, apolipoproteins) to clarify exercise-induced modifications in lipoprotein metabolism.

  • Identify optimal exercise prescriptions tailored to distinct metabolic phenotypes.

  • Integrate nutritional interventions to enhance exercise efficacy.

  • Develop strategies to promote long-term adherence in occupational settings.

Conclusion

This 12-week combined aerobic and resistance exercise program significantly improved lipid profiles—particularly triglycerides—reversed multiple MetS components, and enhanced physical fitness in perimenopausal female university teachers. Benefits were evident across all measured parameters, with the greatest improvements observed among participants with baseline metabolic impairments.

These findings support structured exercise programs as an effective, non-pharmacological strategy for the prevention and management of metabolic syndrome in sedentary occupational populations. The improvements in lipid metabolism and MetS classification underscore the potential of combined exercise interventions to favorably alter disease trajectories in high-risk groups. Future randomized controlled trials with extended follow-up and advanced lipidomic analyses are warranted to confirm these effects and further elucidate underlying mechanisms.