Impact of concurrent aerobic and resistance training on body composition, lipid metabolism and physical function in patients with type 2 diabetes and overweight/obesity: a systematic review and meta-analysis

Abstract

Background: The potential advantages of concurrent aerobic and resistance training (CART) for enhancing cardiometabolic health-related outcomes appear to surpass the outcomes of engaging in aerobic or resistance training alone. The present study aimed to synthesize the available scientific evidence on the effects of CART on body composition, lipid metabolism, and physical function in patients with type 2 diabetes and overweight/obesity.

Methods: PubMed, Scopus, ScienceDirect, Cochrane Library, and Google Scholar were searched from inception to August 7, 2024. The review focused on randomized controlled trials and controlled clinical trials of CART. The Cochrane risk of bias tool was used to assess eligible studies, and the GRADE method to evaluate the reliability of evidence. A random-effects model was used and data were analyzed using standardized mean differences (SMD) and 95% confidence intervals (CI).

Results: A total of 22,878 studies were retrieved; only 20 studies were included, and data were extracted from 1,289 participants (57.0 ± 7.0 years; 31.1 ± 4.6 kg/m²) who met the eligibility criteria. CART group significantly reduced body fat percentage (SMD -0.42, 95% CI [-0.70 to -0.15]), low-density lipoprotein-cholesterol (SMD -0.32, 95% CI [-0.62 to -0.02]), triglycerides (SMD -0.48, 95% CI [-0.71 to -0.24]), total cholesterol (SMD -0.35, 95% CI [-0.58 to -0.12]), and fasting blood glucose levels compared to standard treatment (non-exercising controls). CART significantly increased high-density lipoprotein-cholesterol (SMD 0.44, 95% CI [0.05-0.82]) and improved physical function (cardiorespiratory fitness: SMD 78.78, 95% CI [46.30-111.25]; muscular fitness: SMD 5.19, 95% CI [1.80-8.59]) compared to standard treatment. There were no significant differences in body mass, waist-to-hip ratio, fat mass, and lean body mass between CART and standard treatment. An uncertain risk of bias and poor quality of evidence were observed in the eligible studies.

Conclusions: The present results indicate clear evidence that CART has a beneficial role in the improvement of several cardiometabolic health-related parameters in patients with type 2 diabetes and concomitant overweight/obesity. More trials with robust methodological design are needed to investigate the dose-response effects, training parameters formation, and potential mechanisms.

Keywords: Aerobic exercise; Cardiometabolic health; Metabolic syndrome; Obesity; Overweight; Resistance training.

Figure 1. PRISMA flowchart for search strategy.

The process of study selection for the systematic review and meta-analysis, including identification, screening, eligibility, and inclusion phases. A total of 22,878 records were identified through database searching, and 1,683 duplicates were removed. After screening 21,195 records, 36 full-text articles were assessed for eligibility. Ultimately, 20 studies (22 reports) met the inclusion criteria, while 14 were excluded for reasons such as lack of control group, irrelevant outcomes, or combined interventions.

Figure 2. Summary of the risk of bias assessment.

Summary of risk of bias across all included studies based on the Cochrane risk-of-bias tool. The figure presents the proportion of studies showing low (green), unclear (yellow), and high (red) risk of bias for each domain assessed.

Figure 3. Risk of bias assessment results.

Each study was evaluated across seven domains: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other sources of bias. Green (+) indicates low risk of bias, yellow (?) indicates unclear risk, and red (−) indicates high risk. Most studies demonstrated low or unclear risk in most domains, with a few showing high risk, particularly in performance bias and allocation concealment (Annibalini et al., 2017; Cuff et al., 2003; Dunstan et al., 1998; Ferrer-García et al., 2011; Gibbs et al., 2012; Hale et al., 2022; Jorge et al., 2011; Lambers et al., 2008; Loimaala et al., 2003; Magalhães et al., 2020, 2019; Maiorana et al., 2002; Motahari Rad et al., 2023; de Oliveira et al., 2012; Sabouri et al., 2021; Scheer et al., 2020; Sigal et al., 2007; Swift et al., 2012; Tan, Li & Wang, 2012; Tessier et al., 2000; Yavari et al., 2012; Zarei et al., 2021).

Figure 4. The effect of CART on body mass.

The forest plot displays standardized mean differences (SMD) and 95% confidence intervals (CI) across studies, with subgroup analysis based on intervention duration (≤16 weeks and >16 weeks). No statistically significant reduction in body mass was observed (SMD = −0.05, 95% CI [−0.66 to 0.56]; p = 0.87), and the overall heterogeneity was high (I² = 93%) (Annibalini et al., 2017; Cuff et al., 2003; Ferrer-García et al., 2011; Hale et al., 2022; Jorge et al., 2011; Lambers et al., 2008; Loimaala et al., 2003; Magalhães et al., 2019; Maiorana et al., 2002; Motahari Rad et al., 2023; Sabouri et al., 2021; Sigal et al., 2007; Swift et al., 2012; Tan, Li & Wang, 2012; Tessier et al., 2000; Zarei et al., 2021).

Figure 5. The effect of CART on the waist-to-hip ratio.

Forest plot illustrating the effect of combined aerobic and resistance training (CART) on waist-to-hip ratio in individuals with type 2 diabetes and overweight/obesity. No significant effect was observed compared to standard treatment (SMD = −0.26, 95% CI [−0.69 to 0.17], p = 0.24), with moderate heterogeneity (I² = 41%) (Dunstan et al., 1998; Jorge et al., 2011; Maiorana et al., 2002; Scheer et al., 2020; Tan, Li & Wang, 2012; Zarei et al., 2021).

Figure 6. The effect of CART on body fat.

The forest plot presents standardized mean differences (SMD) with 95% confidence intervals (CI) for each study and the overall pooled estimate. A statistically significant reduction in body fat was observed in the CART group compared to standard treatment (SMD = −0.42, 95% CI [−0.70 to −0.15]; p = 0.002), with moderate heterogeneity (I² = 56%) (Gibbs et al., 2012; Jorge et al., 2011; Magalhães et al., 2019; Maiorana et al., 2002; Motahari Rad et al., 2023; Sigal et al., 2007; Swift et al., 2012; Tan, Li & Wang, 2012; Yavari et al., 2012; Zarei et al., 2021).

Figure 7. The effect of CART on fat mass.

The forest plot shows standardized mean differences (SMD) with 95% confidence intervals (CI). No significant reduction in fat mass was observed following CART compared to standard treatment (SMD = −0.19, 95% CI [−0.50 to 0.11]; p = 0.22), with low heterogeneity across studies (I² = 0%) (Annibalini et al., 2017; Sigal et al., 2007; Zarei et al., 2021).

Figure 8. The effect of CART on lean body mass.

The forest plot shows standardized mean differences (SMD) with 95% confidence intervals (CI). No significant effect of CART on lean body mass was observed compared to standard treatment (SMD = −0.02, 95% CI [−0.33 to 0.30]; p = 0.92), with no observed heterogeneity (I² = 0%) (Magalhães et al., 2019; Sigal et al., 2007; Zarei et al., 2021).

Figure 9. The effect of CART on HDL-C.

The forest plot illustrates a significant improvement in HDL-C following CART compared to standard treatment (SMD = 0.44, 95% CI [0.05–0.82]; p = 0.03), despite moderate heterogeneity among studies (I² = 76%) (Annibalini et al., 2017; Ferrer-García et al., 2011; Gibbs et al., 2012; Jorge et al., 2011; Lambers et al., 2008; Magalhães et al., 2019; Maiorana et al., 2002; Sabouri et al., 2021; Sigal et al., 2007; Tan, Li & Wang, 2012; Zarei et al., 2021).

Figure 10. The effect of CART on LDL-C.

The forest plot shows a statistically significant reduction in LDL-C levels following CART compared to standard treatment (SMD = −0.32, 95% CI [−0.62 to −0.02]; p = 0.03), with moderate heterogeneity observed among studies (I² = 63%) (Annibalini et al., 2017; Ferrer-García et al., 2011; Gibbs et al., 2012; Jorge et al., 2011; Magalhães et al., 2019; Sabouri et al., 2021; Scheer et al., 2020; Sigal et al., 2007; Tan, Li & Wang, 2012; Yavari et al., 2012; Zarei et al., 2021).

Figure 11. The effect of CART on TC.

The forest plot demonstrates a significant reduction in TC following CART compared to standard treatment (SMD = −0.35, 95% CI [−0.58 to −0.12]; p = 0.003), with low heterogeneity (I² = 16%) indicating consistent findings across studies (Annibalini et al., 2017; Ferrer-García et al., 2011; Jorge et al., 2011; Lambers et al., 2008; Magalhães et al., 2019; Maiorana et al., 2002; Sabouri et al., 2021; Scheer et al., 2020; Tan, Li & Wang, 2012; Yavari et al., 2012; Zarei et al., 2021).

Figure 12. The effect of CART on TG.

The meta-analysis revealed a significant reduction in TG following CART compared to standard treatment (SMD = −0.48, 95% CI [−0.71 to −0.24]; p < 0.0001), with moderate heterogeneity (I² = 44%) (Ferrer-García et al., 2011; Gibbs et al., 2012; Jorge et al., 2011; Lambers et al., 2008; Magalhães et al., 2019; Maiorana et al., 2002; Sabouri et al., 2021; Scheer et al., 2020; Sigal et al., 2007; Tan, Li & Wang, 2012; Yavari et al., 2012; Zarei et al., 2021).

Figure 13. The effect of CART on FBG.

The meta-analysis showed a significant reduction in FBG following CART compared to standard treatment (SMD = −0.40, 95% CI [−0.70 to −0.10]; p = 0.009), with moderate heterogeneity (I² = 47%) (Annibalini et al., 2017; Dunstan et al., 1998; Ferrer-García et al., 2011; Jorge et al., 2011; Magalhães et al., 2019; Sabouri et al., 2021; Swift et al., 2012; Tan, Li & Wang, 2012; Yavari et al., 2012).

Figure 14. The effect of CART on cardiorespiratory fitness.

The meta-analysis revealed a significant improvement in cardiorespiratory fitness in the CART group compared to standard treatment (Mean Difference = 78.78, 95% CI [46.30–111.25]; p < 0.00001), with no observed heterogeneity (I² = 0%) (Lambers et al., 2008; Tan, Li & Wang, 2012).

Figure 15. The effect of CART on lower body muscular strength.

A significant increase in lower body strength was observed in the CART group compared to standard treatment (Mean Difference = 5.19, 95% CI [1.80–8.59]; p = 0.003), with moderate heterogeneity (I² = 58%) (Lambers et al., 2008; Loimaala et al., 2003).