Effect of Combined Exercise Training on Physical and Cognitive Function in Women With Type 2 Diabetes

The Impact of Exercise Training on the Brain and Cognition in Type 2 Diabetes, and its Physiological Mediators: A Systematic Review

BACKGROUND

Type 2 diabetes (T2DM) affects brain structure and function, and is associated with an increased risk of dementia and mild cognitive impairment. It is known that exercise training has a beneficial effect on cognition and brain structure and function, at least in healthy people, but the impact of exercise training on these aspects remains to be fully elucidated in patients with T2DM.

OBJECTIVE

To determine the impact of exercise training on cognition and brain structure and function in T2DM, and identify the involved physiological mediators.

METHODS

This paper systematically reviews studies that evaluate the effect of exercise training on cognition in T2DM, and aims to indicate the most beneficial exercise modality for improving or preserving cognition in this patient group. In addition, the possible physiological mediators and targets involved in these improvements are narratively described in the second part of this review. Papers published up until the 14th of January 2025 were searched by means of the electronic databases PubMed, Embase, and Web of Science. Studies directly investigating the effect of any kind of exercise training on the brain or cognition in patients with T2DM, or animal models thereof, were included, with the exception of human studies assessing cognition only at one time point, and studies combining exercise training with other interventions (e.g. dietary changes, cognitive training, etc.). Study quality was assessed by means of the TESTEX tool for human studies, and the CAMARADES tool for animal studies.

RESULTS

For the systematic part of the review, 22 papers were found to be eligible. 18 out of 22 papers (81.8%) showed a significant positive effect of exercise training on cognition in T2DM, of which two studies only showed significant improvements in the minority of the cognitive tests. Four papers (18.2%) could not find a significant effect of exercise on cognition in T2DM. Resistance and endurance exercise were found to be equally effective for achieving cognitive improvement. Machine-based power training is seemingly more effective than resistance training with body weight and elastic bands to reach cognitive improvement. In addition, BDNF, lactate, leptin, adiponectin, GSK3β, GLP-1, the AMPK/SIRT1 pathway, and the PI3K/Akt pathway were identified as plausible mediators directly from studies investigating the effect of exercise training on brain structure and function in T2DM. Via these mediators, exercise training induces multiple beneficial brain changes, such as increased neuroplasticity, increased insulin sensitivity, and decreased inflammation.

CONCLUSION

Overall, exercise training beneficially affects cognition and brain structure and function in T2DM, with resistance and endurance exercise having similar effects. However, there is a need for additional studies, and more methodological consistency between different studies in order to define an exercise program optimal for improving cognition in T2DM. Furthermore, we were able to define several mediators involved in the effect of exercise training on cognition in T2DM, but further research is necessary to unravel the entire process.

Effects of human concurrent aerobic and resistance training on cognitive health: A systematic review with meta-analysis

Background

The rising prevalence of cognitive decline and neurodegenerative diseases, projected to affect 150 million individuals by 2050, highlights the urgent need to enhance neurocognitive health. While both aerobic and resistance training are recognized as effective strategies, their combined effects on cognition remain underexplored.

Objective

This study aimed to determine if concurrent aerobic and resistance training (CT) is effective in enhancing cognitive function.

Methods

Seven English and three Chinese databases were searched from inception to August 2024. Randomised controlled trials (RCTs) examining the effects of CT on global cognition across diverse populations were included. A meta-analysis was performed using a random-effects model in R and Stata, supplemented by subgroup and meta-regression analyses to explore variability.

Results

The meta-analysis included 35 RCTs with 5,734 participants, revealing a positive effect of CT on global cognition (g = 0.32, 95% CI: 0.17-0.46, p < 0.001). Notably, older adults (≥65 years) exhibited greater cognitive benefits (g = 0.33; 95% CI: 0.14-0.51, p < 0.05) compared to younger populations. Significant effects were also observed in clinical populations (g = 0.28; 95% CI: 0.11-0.46, p < 0.001). Exercise frequency and duration positively influenced outcomes, with medium-length interventions (13-26 weeks) demonstrating significant effects (g = 0.21; 95% CI: 0.05-0.37, p = 0.011).

Conclusion

The findings indicate that CT significantly enhances cognitive health, particularly in older adults and clinical populations. Prioritizing strength training, implementing short- to medium-term interventions (4-26 weeks), and maintaining session durations of 30-60 minutes are crucial for optimizing cognitive benefits.

Irisin and neuroinflammation: Challenges and opportunities

Irisin is a myokine that is cleaved from 5-domain type III fibronectin (FNDC5), and is known for its metabolic functions as it stimulates browning of white adipose tissue; similarly, effects on the central nervous system have been described, specifically in neurodevelopmental and neuroprotection processes. The purpose of this review is to describe recent information on the effects of irisin on neuroinflammation to contribute to the knowledge about the mechanisms by which irisin and exercise could generate benefits for some neurological diseases. The review conducted found several studies describing the effect of irisin on pathways such as STAT3, p38, cAMP/PKA/CREB, as well as effects on GFAP protein expression or apoptosis processes in both in vitro and in vivo models; likewise, these pathways are associated with better BDNF expression. Despite increasing information on this topic, it is still necessary to clarify the mechanisms by which irisin has effects on neuroinflammation and this could represent an opportunity to generate more treatments for diseases such as Alzheimer's, Parkinson's or Diabetes Mellitus.

Irisin's emerging role in Parkinson's disease research: A review from molecular mechanisms to therapeutic prospects

Parkinson's disease (PD), a neurodegenerative disorder characterized by impaired motor function, is typically treated with medications and surgery. However, recent studies have validated physical exercise as an effective adjunct therapy, significantly improving both motor and non-motor symptoms in PD patients. Irisin, a myokine, has garnered increasing attention for its beneficial effects on the nervous system. Research has shown that irisin plays a crucial role in regulating metabolic balance, optimizing autophagy, maintaining mitochondrial quality, alleviating oxidative stress and neuroinflammation, and regulating cell death-all processes intricately linked to the pathogenesis of PD. This review examines the mechanisms through which irisin may counteract PD, provides insights into its biological effects, and considers its potential as a target for therapeutic strategies.

Short- and long-term effects of concurrent aerobic and resistance training on circulating irisin levels in overweight or obese individuals: a systematic review and meta-analysis of randomized controlled trials

Background

Concurrent training (CT) is emerging as a practical and effective approach to enhance body composition, cardiovascular function, and muscle mass, thereby elevating overall individual health. This study aims to systematically investigate the effects of short- and long-term concurrent aerobic and resistance training on circulating irisin levels in overweight or obese individuals.

Methodology

The electronic databases, including China National Knowledge Infrastructure, PubMed, Embase, Wan Fang Database, and Web of Science, were systematically searched for articles on "concurrent training" and "irisin" published from their inception to 30 November 2023. The pooled effect size was determined using standardized mean difference (SMD) and corresponding 95% confidence intervals (CIs). The study protocol received registration with the International Prospective Register of Systematic Reviews (CRD42023494163).

Results

All nine studies, encompassing a total of 264 participants, were randomized controlled trials and met the eligibility criteria. Results indicate that short- and long-term concurrent training moderately increased circulating irisin levels compared to the control group (SMD = 0.56, 95% CI [0.33-0.80], p = 0.00; I 2 = 36.6%, heterogeneity p = 0.106). Subgroup analyses revealed that both equal to or less than 10 weeks (SMD = 0.78, 95% CI [0.18-1.37], p = 0.01; I 2 = 62.3%, heterogeneity p = 0.03) and more than 10 weeks (SMD = 0.45, 95% CI [0.14-0.76], p = 0.00; I 2 = 0%, heterogeneity p = 0.54) of concurrent training significantly increased circulating irisin levels in overweight or obese individuals. There were no significant between-group differences (I 2 = 0%, p = 0.34). Additionally, concurrent training significantly increased irisin levels in overweight or obese participants (SMD = 1.06, 95% CI [0.34-1.78], p = 0.00; I 2 = 50.6%, heterogeneity p = 0.13) and in type 2 diabetes patients (SMD = 0.70, 95% CI [0.30-1.10], p = 0.00; I 2 = 0%, heterogeneity p = 0.99). However, no significant effect was observed in patients with metabolic syndrome (SMD = 0.21, 95% CI [-0.25-0.68], p = 0.37; I 2 = 38.7%, heterogeneity p = 0.18). There were significant between-group differences (I 2 = 53.9%, p = 0.11). Lastly, concurrent training significantly increased circulating irisin levels in overweight or obese individuals aged 45-60 years (SMD = 0.56, 95% CI [0.25-0.86], p = 0.00; I 2 = 6.5%, heterogeneity p = 0.38), and a significant increase in irisin levels was observed 12 h post-intervention (SMD = 0.70, 95% CI [0.35-1.05], p = 0.00; I 2 = 0%, heterogeneity p = 0.74). However, none of the above categorical variables showed significant between-group differences.

Conclusions

Short- and long-term concurrent training can effectively improve circulating irisin levels in overweight or obese individuals. However, the effects of short- and long-term concurrent training should consider the participants' health status, age, and the timing of post-exercise measurements to maximize health benefits.

The impact of early-life exercise on CREB-signaling pathway and hippocampus neuroplasticity in diabetic adult male rats; the study of developmental model

BACKGROUND

Childhood exercise enhances brain structure, while diabetes detrimentally affects it. This study examines early-life exercise's influence on adult diabetic rats' memory and neuroplasticity.

METHODS

Male Wistar pups were divided into Control, Diabetes, Exercise Training, and Diabetes exercise groups. Diabetes was induced on day 23 with Alloxan (200 mg/kg). A 3-week regimen included aerobic and resistance training thrice weekly. The aerobic intensity was 70%, and resistance varied from 50% to 100% of the maximal carrying capacity (MCC). Following the last training sessions, spatial memory and retrieval tests were performed in infancy, childhood, and emerging adulthood using the Morris Water Maze test (MWM). The hippocampus was excised to measure protein and gene expression of brain-derived neurotrophic factor (BDNF), calmodulin-dependent protein kinase (CAMKII), N-methyl-D-aspartate receptors (NMDAR), and cAMP-response element-binding protein (CREB) by western blotting and reverse transcription-polymerase-chain reaction (RT-PCR) methods. Blood samples were collected during each developmental stage to measure glucose levels, at the study's conclusion, to assess Interleukin-1β levels using the ELISA method. The Nissel staining assessed dead hippocampal cells in CA1.

RESULTS

Post-natal exercise improved spatial memory (p < 0.05) and glucose levels (p < 0.05) in diabetic rats during adolescence and emerging adulthood. Despite reduced mRNA expression (NMDAR 40%, BDNF 62%, CREB 43%, CAMKII 66%), diabetic rats, by study end, showed increased BDNF, NMDARR, CAMKII, CREB protein/gene expression (p < 0.05) in emerging adulthood for both training groups.

CONCLUSION

Early-life exercise influenced hippocampal BDNF/NMDAR-CAMKII/CREB pathways in a diabetic rat model, highlighting post-natal exercise's role in neuroplasticity memory enhancement and improved glucose level.

Effectiveness of Combined Aerobic and Resistance Exercise on Cognition, Metabolic Health, Physical Function, and Health-related Quality of Life in Middle-aged and Older Adults With Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis

OBJECTIVES

To evaluate the effectiveness of combined aerobic and resistance exercise on cognition, metabolic health, physical function, and health-related quality of life (HRQoL) in middle-aged and older adults with type 2 diabetes mellitus (T2DM).

DATA SOURCE AND STUDY SELECTION

Systematic search of CINAHL, Cochrane, EMBASE, Scopus, PubMed, ProQuest Dissertation and Thesis, PsycINFO, Web of Science databases, and gray literature from Google Scholar. Pertinent randomized controlled trials (RCTs) were selected. The Protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO CRD42023387336).

DATA EXTRACTION

The risk of bias was evaluated using the Cochrane Risk of Bias tool by 2 reviewers independently. Outcome data were extracted in a fixed-effect model if heterogeneity test were not significant and I2≤50%; otherwise, the random-effects model was used.

DATA SYNTHESIS

Sixteen studies with 2426 participants were included in this review. Combined aerobic and resistance exercise had significant positive effects on cognition (SMD=0.34, 95% CI: 0.13 to 0.55), metabolic health on HbA1c (SMD=-0.35, 95% CI: -0.48 to -0.22) and lipid profile (total cholesterol SMD=-0.20, 95% CI: -0.34 to -0.07; low-density lipoprotein SMD=-0.19, 95% CI: -0.33 to -0.05; high-density lipoprotein SMD=0.25, 95% CI: 0.12 to 0.39; and triglycerides SMD=-0.18, 95% CI: -0.31 to -0.04), physical function on aerobic oxygen uptake (SMD=0.58, 95% CI: 0.21 to 0.95) and body mass index (MD=-1.33, 95% CI: -1.84 to -0.82), and physical HRQoL (MD=4.17, 95% CI: 0.86 to 7.48). Our results showed that clinically important effects on cognition may occur in combining the low-moderate intensity of aerobic exercise and progressive intensity of resistance training, the total duration of the exercise needs to be at least 135 minutes per week, among which, resistance training should be at least 60 minutes.

CONCLUSION

Combined aerobic and resistance exercise effectively improves cognition, ameliorates metabolic health, enhances physical function, and increases physical HRQoL in middle-aged and older adults with T2DM. More RCTs and longitudinal follow-ups are required to provide future evidence of structured combined aerobic and resistance exercise on other domains of cognition.

Trends in Multicomponent Training Research in the Aged Population: A Bibliometric Analysis

The proportion of aged populations is increasing worldwide. Exercise has a palliating effect on some adverse implications of aging. Multicomponent training (MCT) is a recommended form of exercise for the aged population. The aims of this research were to (1) study the number of publications regarding MCT in the aged population following an exponential growth rate; (2) identify the journals, authors, and countries that stand out the most in this area; and (3) describe the most common themes and used keywords in this field. The analysis was performed through the traditional laws of bibliometrics, including, Price's, Lotka's, Bradford's, and Zipf's law. All documents published in journals indexed in the Web of Science (WoS) Core Collection from 2001 to November 2023 that met the inclusion criteria were included. The 485 documents included in this review revealed that the number of annual publications experienced an exponential growth phase, 15 journals with six or more publications formed the core journals on this topic, and the author Mikel Izquierdo and his collaborative network topped the lists of prominent and prolific co-authors. Spain was the leading country in number of publications. Various thematic lines and keywords regarding strength, sarcopenia, quality of life, falls, balance, dual-task exercise, and cognitive and physical functioning were identified. In conclusion, this work confirmed that research on this topic is going through an exponential growth phase and provided detailed information about the journals, authors, and countries involved in the subject, as well as the keywords most frequently used in the subject matter.

The effect of multi-component exercise on cognition function in patients with diabetes: A systematic review and meta-analysis

BACKGROUND

This meta-analysis investigated the influence of exercise on cognitive function in people living with diabetes.

METHODS

Stringent criteria for literature inclusion and exclusion were defined. Searches were conducted across four English databases to gather randomized controlled trials investigating exercise interventions for cognitive function in people living with diabetes. Outcome indicators from 1193 subjects across 12 articles were analyzed using RevMan 5.4 software.

RESULTS

Exercise intervention demonstrated the ability to mitigate cognitive decline in people living with diabetes, with a combined effect size (standardized mean difference) of 0.91, 95% CI: 0.28, 1.54, P < 0.00001. The intervention effect showed significant modulation by intervention content (I2 = 95%), intervention duration (I2 = 95%), intervention frequency (I2 = 95%), and intervention cycle (I2 = 96%). Among these factors, multi-component exercise, sessions >40 minutes, exercise frequency >4 times per week, and sustained exercise for >6 months were paramount, all with P < 0.05.

CONCLUSION

Exercise intervention emerges as a viable strategy for delaying cognitive decline in people living with diabetes. Its efficacy is subject to modulation by various variables. Optimal intervention includes multi-component exercise, individual sessions lasting 40-60 minutes, exercising >4 times a week, and continuous exercise for over 6 months.

Feasibility and preliminary efficacy of different intensities of functional training in elderly type 2 diabetes patients with cognitive impairment: a pilot randomised controlled trial

BACKGROUND

Aging and type-2 diabetes (T2D) are the most important risk factors for cognitive impairment and Alzheimer's disease. Exercise training is an effective, safe, and practical intervention in improving glucose metabolism, physical function, and cognitive disorders. This pilot study investigated the feasibility and preliminary efficacy of high-intensity low-volume (HIFT) vs. low-intensity high-volume (LIFT) functional training in elderly T2D patients with cognitive impairment.

METHODS

Forty-eight elderly T2D patients (31 female, 17 male, age 67.5 ± 5.8 years, MMSE score 18.8 ± 2.6, FBG 209.5 ± 37.9) were randomly assigned to HIFT, LIFT and control groups. Cognitive impairment was diagnosed with MMSE ≤ 23 based Iranian society. The SDMT, CVLT-II, BVMT-R, and Stroop tests were used to evaluated processing speed, learning, memory and attention respectively. Physical fitness tests include: tandem stance and walk test; TUG; 6MWT, 10MWT; SSST; 5TSTS; and hand grip was used to evaluated static and dynamic balance, agility, walking endurance, gait speed, lower limb function and lower and upper body strength respectively. As well as, Biochemical (FBG, insulin, HOMA-IR, HbA1c) and physiological outcomes (SBP, and DBP) were assessed. The HIFT group performed six weeks of functional training (three sessions per week) with 120-125% of the lactate threshold. The LIFT group performed six weeks of functional training (five sessions per week) with a 70-75% lactate threshold. Feasibility, safety, and acceptability of exercise programs were assessed at the end of the study.

RESULT

HIFT showed a higher adherence rate (91% vs. 87.5%), safety, and acceptability compared to LIFT. MMSE and Stroop scores, 6MWT, FBG, insulin, HOMA-IR, HbA1c, SBP, and DBP significantly improved in HIFT (all, P ≤ 0.004) and LIFT (all, P ≤ 0.023). Changes in 6MWT, FBG, insulin, HOMA-IR, and HbA1c in HIFT (all, P ≤ 0.001) and LIFT (all, P ≤ 0.008) were significant compared to the control group. Changes in Stroop scores were significant only in the HIFT group compared to the control group (P = 0.013). SDMT, CVLT-II, BVMT-R, balance test, 10MWT, SSST, TUG and hang grip significantly improved only in HIFT (all, P ≤ 0.038).

CONCLUSION

HIFT vs. LIFT is a safe, feasible, and effective approach for improving some aspects of physical, biochemical, and cognitive function in elderly T2D patients with cognitive impairment. This pilot study provides initial proof-of-concept data for the design and implementation of an appropriately powered randomised controlled trial (RCT) of HIFT vs. LIFT in a larger sample of elderly T2D patients with cognitive impairment.

TRIAL REGISTRATION

Randomized controlled trial (RCT) (Iranian Registry of Clinical Trials, trial registration number: IRCT20230502058055N1. Date of registration: 11/06/2023.

Qigong Training Effects on Brain-Derived Neurotrophic Factor and Cognitive Functions in Sedentary Middle-Aged and Elderly Females With Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) heightens dementia and cognitive decline risk, notably impacting working memory and executive functions. This study investigates the impact of 8 weeks of qigong training on cognitive functions, blood pressure, plasma brain-derived neurotrophic factor (pBDNF), antioxidant, and biochemical outcomes in sedentary middle-aged and elderly women with T2DM. Thirty-five sedentary middle-aged and elderly women with T2DM were assigned to qigong exercise (QG = 19) or control (CG = 16) groups. Qigong exercise group performed the qigong exercise three times per week, for 8 weeks. The cognitive functions and pBDNF as primary and secondary outcomes (blood pressure parameters, antioxidant, and blood cell indices) were measured at baseline and postexercise training. While cognitive performance did not change, there was a significant interaction (Group × Time), indicating reduced pBDNF levels postintervention in the qigong exercise group (p < .05). Both mean arterial blood and pulse pressure values decreased after qigong training (p < .05), but no significant interaction effects (Time × Group) were seen. There was a pulse pressure reduction after qigong training (p < .05), which was significantly correlated with the increase in longest digit span forward (r = −.34, p < .05). Antioxidant levels decreased from PRE to POST within both groups. This study demonstrated that 8 weeks of qigong training reduced pBDNF levels in sedentary middle-aged and elderly women with T2DM, which is unrelated to cognitive function improvements but possibly indicating a favorable response to exercise. Additionally, reduced blood and pulse pressure, potentially enhancing cognitive function by favorably impacting the autonomic nervous system by qigong training.