Muscle fatigability in type 2 diabetes

Comparison of fatigue and functional status in elderly type 2 diabetes patients versus age and gender matched individuals

Introduction

Fatigue is a common yet not frequently explored complication of diabetes. There are fewer studies available on the impact of diabetes on the severity of fatigue and the functional status of patients.

Methods

Fifty individuals meeting the inclusion criteria were included. The individuals were divided into two groups: group A (diabetic elderly individuals) and group B (nondiabetic age and gender-matched individuals). An observational analytical study was conducted. Outcome measures used were: fatigue severity scale (FSS), lower extremity functional scale (LEFS), 6-minute walk distance (6MWD), and 30-second chair stand test. SPSS 16 was used to analyze data.

Results

As per the normality test, a between-group comparison of fatigue severity scale (FSS) score, chair stand test score, and LEFS score was carried out by a nonparametric Mann-Whitney test, which showed a statistically significant difference between the groups (P < 0.05). Between-group comparison of 6MWD was carried out by parametric unpaired t test. The results showed a statistically significant difference in the distance walked by both groups.

Conclusion

Higher levels of fatigue and impaired functional status along with reduced strength and function of lower limbs was seen in elderly patients with type 2 diabetes Inclusion of symptom assessment and strategies to reduce the burden of fatigue in diabetes patient should be incorporated.

Hand loading, rates of perceived exertion, and usability during assisted walking in patients with type 2 diabetes mellitus

BACKGROUND

Patients suffering from a diabetic foot ulcer often receive a non-weight bearing prescription of the affected limb to promote healing. Total unilalteral offloading of the affected foot necessitates walking aids that require loading at the hands during ambulation. Excessive loading at the hands can increase of the risk of crutch palsy. In addition, certain walking aids can also be more strenuous and less comfortable to use than others, resulting in lower prescription compliance. This study aimed to investigate hand loading, rates of perceived exertion, and usability of typically prescribed walking aids in patients with Type 2 Diabetes.

METHODS

Twenty patients (12 F | 8 M, 61.0 ± 10.36 yrs., 90.54 ± 13.34 kg, 1.71 ± 0.08 m) walked as much as 200 m without assistance and with crutches, walkers, and a wheeled knee walker instrumented with flexible force-sensing pads on walking aid handles. Patients rated exertion using a Modified Borg Scale and completed a System Usability Scale questionnaire after each walking condition with or without walking aids.

FINDINGS

Results show that using a wheeled knee walker required 94% less hand loading than crutches and walkers. Patients reported 45% lower exertion with the WKW compared to crutches and walkers, and scored the usability of the wheeled knee walker 106% higher than crutches and walkers.

INTERPRETATION

The wheeled knee walker could be the preferred walking aid for total unilateral offloading because of the reduced loading demand at the hands, lower exertion during use, and greater usability compared to crutches and walkers.

Novel Approach for Glycemic Management Incorporating Vibration Stimulation of Skeletal Muscle in Obesity

Because obesity is associated with impaired glucose tolerance and type 2 diabetes (T2D), it is important to manage the blood glucose level at an early stage. Nevertheless, people with obesity have significantly lower resistance to muscle fatigue after exercise and exercise adherence. Therefore, we developed a novel "Relaxing-Vibration Training (_RVT)" consisting of 25 postures using vibration stimulation of skeletal muscle and determined the feasibility of _RVT for glycemic management. Thirty-one participants with obesity were enrolled in a controlled trial (CT) and experimental trial (ET) based on a 75 g oral glucose tolerance test (OGTT). During the CT, participants were required to rest in a quiet room. During the ET, the _RVT program (50 Hz, 4 mm), consisting of 25 postures of relaxation and stretching on the vibratory platform, was performed for 40 min. Subsequently, the participants rested as in the CT. Subjective fatigue and muscle stiffness measurements and blood collection were conducted before and after _RVT. In both the CT and ET, interstitial fluid (ISF) glucose concentrations were measured every 15 min for 2 h. The incremental area under the curve value of real-time ISF glucose during an OGTT was significantly lower in the ET than in the CT (ET: 7476.5 ± 2974.9, CT: 8078.5 ± 3077.7, effect size r = 0.4). Additionally, the levels of metabolic glucose regulators associated with myokines, muscle stiffness, and subjective fatigue significantly improved after _RVT. This novel _RVT suggests that it is effective in glycemic management with great potential to improve impaired glucose tolerance and T2D with obesity in the future.

Mechanisms underlying altered neuromuscular function in people with DPN

Diabetes alters numerous physiological functions and can lead to disastrous consequences in the long term. Neuromuscular function is particularly affected and is impacted early, offering an opportunity to detect the onset of diabetes-related dysfunctions and follow the advancement of the disease. The role of physical training for counteracting the deleterious effects of diabetes is well accepted but at the same time, it appears difficult to reliably assess the effects of exercise on functional capacity in patients with diabetic peripheral neuropathy (DPN). In this paper, we will review the specific characteristics of various neuromuscular dysfunctions associated with diabetes according to the DPN presence or not, and their changes over time. We present several propositions regarding the onset of neuromuscular alterations in people with diabetes compared to people with DPN. It appears that motor unit loss and neuromuscular transmission impairment are among the main mechanisms explaining the considerable degradation of neuromuscular function in the transition from a diabetic to neuropathic state. Rate of force development and contractile properties could start to decrease with the onset of preferential type II fiber atrophy, commonly reported in people with DPN. Finally, M_max amplitude could decrease with neuromuscular fatigue only in people with DPN, reflecting the fatigue-related neuromuscular transmission impairment reported in people with DPN. In this review, we show that the different neuromuscular parameters are altered at different stages of diabetes, according to the presence of DPN or not. The precise evaluation of these parameters might participate in adapting the physical training prescription.

Impact of resistance training on muscle fatigue in type 2 diabetes mellitus patients during dynamic fatigue protocol

BACKGROUND

Type 2 diabetes mellitus (T2DM) is often accompanied with several neuromuscular complications of which muscle fatigue is one of the scantily studied and less-explored complication of this disease.

OBJECTIVE

To investigate the effects of resistance training (RT) on muscle fatigue markers from electromyography (EMG) and capillary blood in T2DM patients.

METHODS

Forty T2DM patients were randomized to either RT (n = 20) or control group (n = 20). They were assessed for EMG indices of muscle fatigue along with blood lactate (at three time points: Lactate_pre, Lactate_peak, Lactate_post) during a dynamic fatigue protocol. Dynamic fatigue protocol consisted of 5 sets of leg press exercise at 10 repetition maximum intensity. RT group performed moderate intensity (65%-75% 1 repetition maximum) RT 3 times/week for 12 weeks. Control group followed usual routine.

RESULTS

Findings revealed that EMG amplitude (root mean square) and Dimitrov's muscle fatigue index (FI_nsmk) decreased significantly while median frequency (MF) increased significantly during the dynamic fatigue protocol for both vastus medialis (Root mean square, p = .02; FI_nsmk, p = .001; MF, p < .001) and vastus lateralis muscle (Root mean square, p= .04,FI_nsmk,p = .01; MF, p < .001) post-RT. Blood lactate responses did not change after RT (Lactate_pre, p = .55; Lactate_peak, p = .91; Lactate_post, p = .33).

CONCLUSIONS

Findings of the present study illustrated that moderate intensity RT led to a significant reduction muscle fatigue in knee extensor muscles of T2DM patients. These results reinforce the utilization of RT in patients with T2DM.

Walking Attenuates Postprandial Glycemic Response: What Else Can We Do without Leaving Home or the Office?

We evaluated the effects of different exercise types suitable for a home/work setting on the postprandial glucose response. Twenty-three healthy, active, young individuals performed one of two studies (12 in Study 1 and 11 in Study 2), with four randomized protocols each. After a meal high in carbohydrate content (1 g of carbohydrate per kg of body weight), in Study 1, participants performed 30 min of either walking (WALK), bench stepping exercise (STEP) or isometric wall squat (SQUAT); in Study 2, participants performed 30 min of either walking (WALK), neuromuscular electrical stimulation alone (P_NMES) or superimposed on voluntary muscle contraction (VC_NMES). In both studies, participants performed a prolonged sitting condition (CON) that was compared to the exercise sessions. In Study 1, WALK and STEP significantly reduced the glucose peak compared to CON (p < 0.011). In Study 2, the peak was significantly reduced in WALK compared to CON, P_NMES and VC_NMES (p < 0.011) and in VC_NMES compared to CON and P_NMES (p < 0.011). A significant reduction of 3 h glucose iAUC was found for WALK and VC_NMES compared to CON and P_NMES (p < 0.033). In conclusion, WALK is the most effective strategy for improving the postprandial glycemic response. However, STEP and VC_NMES can also be used for reducing postprandial glycemia.

Alterations to plantar loading and ankle range of motion of the contralateral foot during assisted walking in patients with Type 2 Diabetes Mellitus

AIMS

Patients with diabetic foot ulcers are instructed to be non-weight bearing on the affected limb to promote healing. Therefore, the aim of this study was to investigate the effect of different assistive devices on whole foot plantar loading, peak forefoot force, ankle range of motion, and locomotion speed during gait in patients with Type 2 Diabetes Mellitus.

METHODS

Participants walked normally, with crutches, a walker, and a wheeled knee walker (WKW) in randomized order. Force sensitive insoles and 3D motion capture were used to record plantar normal force and ankle kinematics. Force sensitive pads were wrapped around handles of the crutches and walker to measure bodyweight offloaded onto the assistive device. An instrumented WKW was used to measure bodyweight offloaded onto the handlebars and knee cushion.

RESULTS

Locomotion with the WKW produced the lowest whole foot plantar loading and peak forefoot force in the propulsive limb, while also producing the greatest ankle range of motion and locomotion speed amongst assistive devices.

CONCLUSIONS

This pre-clinical study found that the WKW could be the preferred assistive device for total unilateral offloading of diabetic foot ulcers as it reduced propulsive limb whole foot and forefoot plantar loading while retaining ankle range of motion and locomotion speed.

Morphological and functional changes in skeletal muscle in type 2 diabetes mellitus: A systematic review and meta-analysis

INTRODUCTION

Changes in the skeletal muscle are common in patients with type 2 diabetes mellitus (T2DM). These changes impair your motor skills.

OBJECTIVE

This systematic review aimed to investigate changes in skeletal muscle in patients with T2DM.

METHODS

The search was carried out in the PubMed, Scopus, and Web of Science databases until December 1, 2021. Observational studies that evaluated musculoskeletal changes in people with T2DM were included. The review was based on PRISMA recommendations. The primary parameters analyzed were muscle strength, muscle mass, muscle power, and muscle endurance.

RESULTS

Forty-eight studies were included, with a total of 26,042 participants. The results revealed that T2DM is associated with a reduction in handgrip [-2.64 (CI 95% = -3.33 to -1.95, Z = -7.50, p < .0001], and knee extension muscle strength [-0.56 (CI 95% = -0.76 to -0.36, Z = -5.64, p < .0001)], a higher percentage of type II fibers [11.74 (CI 95% = 6.24 to 17.25, Z = 4.18, p < .0001)], and a lower percentage of type I fibers [-15.69 (CI 95% = -18.22 to -13.16, Z = -12.16, p < .0001], in addition to a greater thickness of the calcaneus tendon (p < .0001).

CONCLUSION

Individuals with T2DM present skeletal muscle impairments, mainly reduced muscle strength, mass, and endurance; increase in the thickness of the calcaneus tendon, and alteration in the proportion of type I and II fibers, even in the initial stage of the disease.

The Effects of Passive Simulated Jogging on Parameters of Explosive Handgrip in Nondiabetics and Type 2 Diabetics: A Single Arm Study

Aims

Type 2 diabetes (T2D) is associated with sarcopenia and decreased muscle strength. Explosive and isometric voluntary handgrip strengths (EHGS and HGS) are frequently utilized methods to ascertain health status and a marker of overall muscle strength. We have previously shown that a portable, motorized device, which produces effortless, rapid stepping in place (passive simulated jogging device (JD)), improves glucose homeostasis. This study quantitatively evaluated the effects of JD in modifying parameters of the modified EHGS curve in T2D and nondiabetic (ND) subjects.

Methods

Twenty-one adult participants (11 ND and 10 T2D) (mean age: 41.3 ± 13.5 yr) performed a modified explosive handgrip strength (EHGS) test on study day 1 followed by daily use of JD (90 min per day) for 7 days. The EHGS was repeated after 3 and 7 days' use of JD (JD3 and JD7) and 3 days after completion of JD (Carryover). EHGS curves were analyzed for the following: maximal peak force value (MAX); rate of force development at 25%,75%, and 90% of maximum force; and maximum force (RFD_25%, RFD_75%, RFD_90%, and RFD_max); time to 90%, 75%, and 25% of maximal force (t₉₀, t₇₅, t₂₅) and time to maximal force (t_max); and the integrated area under the curve for force vs. time until task failure (iAUC_TF); and fatigue resistance times at 50% and 25% of maximal force (FR₅₀ and FR25) and fatigue resistance time to task failure (FR_TF).

Results

At baseline, T2D had lower MAX compared to ND. There were no differences at baseline for force development time or fatigue resistance time between T2D and ND. In both T2D and ND, 7 days of JD increased FR₂₅ and FR_TF and iAUC_TF compared to baseline.

Conclusion

JD for at least 7 days prior to EHGS increased time to task failure (fatigue resistance) and iAUC_TF of the force-time curve. JD is a reasonable intervention to decrease sedentary behavior and improve muscle fatigue resistance under various clinical and nonclinical scenarios. This trial is registered with NCT03550105 (08-06-2018).

Neuromuscular dysfunction and exercise training in people with diabetic peripheral neuropathy: A narrative review

Diabetic peripheral neuropathy (DPN) is a common condition that is associated with neuromuscular dysfunction and peripheral sensory impairment. These deficits predispose patients to sensory and motor system limitations, foot ulcers and a high risk of falls. Exercise training has been proposed as an effective tool to alleviate neural deficits and improve whole-body function. Here we review the effects of DPN on neuromuscular function, the mechanisms underlying this impairment, and the neural and muscular adaptations to exercise training. Muscle dysfunction is an early hallmark of DPN. Deficits in muscle strength, power, mass and a greater fatigability are particularly severe in the lower extremity muscles. Non-enzymatic glycation of motor proteins, impaired excitation-contraction coupling and loss of motor units have been indicated as the main factors underlying muscular dysfunction. Among the exercise-based solutions, aerobic training improves neural structure and function and ameliorates neuropathic signs and symptoms. Resistance training induces marked improvement of muscle performance and may alleviate neuropathic pain. A combination of aerobic and resistance training (i.e., combined training) restores small sensory nerve damage, reduces symptoms, and improves muscle function. The evidence so far suggests that exercise training is highly beneficial and should be included in the standard care for DPN patients.

Type 2 Diabetes Mellitus Patients Manifest Greater Muscle Fatigability Than Healthy Individuals During Dynamic Fatigue Protocol

OBJECTIVE

The present study aimed to investigate the electromyographic (EMG) indices of muscle fatigue along with biochemical marker of fatigue-that is, blood lactate-during a dynamic fatigue protocol in individuals with type 2 diabetes mellitus (T2DM) vs a healthy control group. Secondarily, it aimed to examine the association between EMG indices of muscle fatigue and blood lactate in these patients.

METHODS

Thirty-four participants took part in the study: 19 individuals with T2DM (age, 53.5 ± 6.85 years) and 15 age-matched healthy controls (age, 50.2 ± 3.55 years). Participants performed a dynamic fatigue protocol consisting of 5 sets of 10 repetitions each at an intensity of the 10-repetition maximum. Surface EMG of the vastus medialis and vastus lateralis muscles was recorded during the dynamic fatigue protocol, and EMG indices such as median frequency (MF), slope of MF (MF_slope), Dimitrov muscle fatigue spectral index, and root-mean-square were evaluated for each contraction across all the 5 sets. Blood lactate concentrations were also assessed 3 times during the fatigue protocol.

RESULTS

Findings revealed that EMG muscle fatigue indices such as MF, MF_slope, and Dimitrov muscle fatigue spectral index were significantly altered in individuals with T2DM vs healthy individuals across the sets and repetitions for both the vastus medialis (P < .001) and vastus lateralis muscles (P < .001). There was a significantly greater rise in blood lactate in individuals with T2DM than in healthy individuals (P < .001), which was not found to be associated with changes in EMG indices of muscle fatigue.

CONCLUSION

Findings suggest the existence of significantly greater fatigue in the knee extensor muscles of individuals with T2DM than healthy individuals.

Clinical and Structural Outcomes After Rotator Cuff Repair in Patients With Diabetes: A Meta-analysis

Background:

The impact of diabetes on clinical and structural outcomes after rotator cuff repair remains controversial.

Purpose/Hypothesis:

The purpose of this study was to compare clinical outcomes and retear rates after rotator cuff repair in patients with and without diabetes. Our hypotheses were that adequate control of diabetes would decrease the retear rate after rotator cuff repair and that patients with diabetes would have worse clinical outcomes.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

The PubMed, Embase, and Cochrane Library databases were searched for studies comparing outcomes in patients with and without diabetes after full-thickness rotator cuff repair. Clinical outcome analysis included the Constant score, the American Shoulder and Elbow Surgeons (ASES) score, and the University of California–Los Angeles shoulder rating scale; we compared preoperative, postoperative, and change in functional scores from baseline to final follow-up among the included studies. The pooled relative risk was calculated using a random-effects model for retear rates. Clinical outcomes were also pooled using a random-effects model.

Results:

Overall, 10 studies were included. Compared with patients without diabetes, patients with diabetes had a worse preoperative ASES score (P = .009) as well as worse postoperative Constant score (final follow-up range, 9-103 months; P = .0003). However, there was no significant difference in the absolute mean change in clinical outcomes between patients with and without diabetes. Diabetes was associated with a higher retear rate (19.3% in patients without diabetes vs 28.2% in patients with diabetes; P < .0001). The retear rate according to the severity of sustained hyperglycemia in the subgroup analysis was 14.6% in patients without diabetes, versus 22.7% in patients with well-controlled diabetes (<7.0% of preoperative serum HbA1c level; P = .12) and 40.0% in patients with uncontrolled diabetes (HbA1c level ≥7.0%; P < .00001).

Conclusion:

This meta-analysis suggests that diabetes mellitus is associated with an increased risk of retears after rotator cuff repair, and improved blood glucose control may reduce the risk of retears in patients with diabetes mellitus. Although effective glycemic control was associated with a decreased risk of retears in patients with diabetes, we could not prove causation because of potential bias and confounding in the included studies.

Muscle fatigability in patients with type 2 diabetes: relation with long-term complications

AIMS

It is unclear whether long-term complications play a role in muscle fatigue characteristic of patients with type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the association between muscle fatigability and microvascular and macrovascular complications in patients with T2DM.

METHODS

One-hundred forty-six patients with T2DM (80 males, 66 females, aged 66.9 ± 7.9 years) were recruited. Maximal voluntary contraction (MCV) and endurance time (ET, 50% of the MVC) were assessed at the knee extensor muscles with an isometric dynamometer. Univariate and multivariate correlations of ET values with diabetic complications, a wide range of surrogate measures of these sequelae, and cardiovascular risk factors were examined.

RESULTS

A higher muscle fatigability was detected in patients with diabetic peripheral neuropathy (DPN, ET: -32.4%), cardiovascular disease (CVD, ET: -32.1%), retinopathy (ET: -35.8%), and nephropathy (ET: -30.4%). At univariate analysis, muscle fatigability was associated with age, physical activity level, diabetes duration, HbA_1c , systolic blood pressure, albuminuria, eGFR, and several parameters of nervous and vascular function. Multivariate analysis showed that, after adjusting for covariates, ET was independently associated with sensory nerve conduction velocity, vibration perception threshold at malleolus, and ankle-brachial index. In addition, ET values were independently associated with the presence of DPN, CVD, and retinopathy.

CONCLUSIONS

In T2DM, muscle fatigability is associated with presence of DPN, CVD, and retinopathy. Such defect appears to be mediated predominantly by sensory nerve and peripheral vascular dysfunction.

Diffusion Tensor Imaging of the Calf Muscles in Subjects With and Without Diabetes Mellitus

BACKGROUND

Diffusion tensor imaging (DTI) has been used to characterize calf skeletal muscle architecture.

PURPOSE

To assess the diffusional properties of the calf muscles of subjects with and without diabetes, at rest and during isometric plantarflexion exercise.

STUDY TYPE

Prospective.

SUBJECTS

Twenty-six subjects in two groups: 13 healthy and 13 subjects with type 2 diabetes (DM); each group consisted of seven females and six males.

FIELD STRENGTH/SEQUENCE

3T/2D single-shot spin echo planar imaging.

ASSESSMENT

Fractional anisotropy (FA), mean diffusivity (MD), diffusion eigenvalues, and fiber tracking indices were obtained from the medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus (SOL) muscles of the calf at rest and during isometric plantarflexion exercise.

STATISTICAL TESTS

We used a combination of nonparametric (Wilcoxon) and parametric (t-test) statistical assessments.

RESULTS

The medial gastrocnemius muscle had more indices with significant differences between the two groups (six indices with P < 0.05) than did the lateral gastrocnemius (three indices with P < 0.05) and soleus muscles (only one index with P < 0.05). While the healthy group showed elevated MD values from rest to exercise (MG = 5.83%, LG = 13.45%, and SOL = 11.68%), the diabetic MD showed higher increases (MG = 19.74%, LG = 29.31%, and SOL = 20.84%) that were different between groups (MG: P = 0.009, LG: P = 0.037, and SOL: P = 0.049).

DATA CONCLUSION

Our results indicate considerable diffusional changes between healthy subjects and subjects with diabetes at rest and during isometric plantarflexion exercise in the calf muscles. The medial gastrocnemius muscle displayed the most diffusion sensitivity to diabetes-related microstructural changes.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1285-1295.

Impairment of respiratory muscle strength in Berardinelli-Seip congenital lipodystrophy subjects

BACKGROUND

Berardinelli-Seip Congenital Generalized Lipodystrophy (BSCL) is an ultra-rare metabolic disease characterized by hypertriglyceridemia, hyperinsulinemia, hyperglycemia, hypoleptinemia, and diabetes mellitus. Although cardiovascular disturbances have been observed in BSCL patients, there are no studies regarding the Respiratory Muscle Strength (RMS) in this type of lipodystrophy. This study aimed to evaluate RMS in BSCL subjects compared with healthy subjects.

METHODS

Eleven individuals with BSCL and 11 healthy subjects matched for age and gender were included in this study. The Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP), and Peripheral Muscle Strength (PMS) were measured for three consecutive years. BSCL subjects were compared to healthy individuals for MIP, MEP, and PMS. Correlations between PMS and MIP were also analyzed. The genetic diagnosis was performed, and sociodemographic and anthropometric data were also collected.

RESULTS

BSCL subjects showed significantly lower values for MIP and MEP (p <  0.0001 and p = 0.0002, respectively) in comparison to healthy subjects, but no changes in handgrip strength (p = 0.15). Additionally, we did not observe changes in MIP, MEP, and PMS two years after the first analysis, showing maintenance of respiratory dysfunction in BSCL subjects (p = 0.05; p = 0.45; p = 0.99). PMS and MIP were not correlated in these subjects (r = 0.56; p = 0.18).

CONCLUSION

BSCL subjects showed lower respiratory muscle strength when compared with healthy subjects; however, PMS was not altered. These findings were maintained at similar levels during the two years of evaluation. Our data reveal the first association of BSCL with the development of respiratory muscle weakness.

A new hypoglycemic mechanism of catalpol revealed by enhancing MyoD/MyoG-mediated myogenesis

AIMS

Enhancing myogenesis has been identified as a possible target to improve insulin sensitivity and protect against metabolic diseases. Catalpol, an iridoid glycoside, has been shown to exert a hypoglycaemic effect by improvement of insulin sensitivity; however, the underlying mechanism remains unknown. In this study, we tested whether catalpol has the potential to improve insulin sensitivity by augmenting myogenesis.

MAIN METHODS

We examined the hypoglycaemic mechanism of catalpol in db/db mice and C2C12 cells. db/db mice were treated with catalpol (200 mg/kg) for 8 consecutive weeks. Serum analysis, skeletal muscle performance and histology, and gene and protein expression were performed. In vitro glucose uptake, gene and protein expression were determined, and small interfering RNA was used to identify the underlying hypoglycaemic mechanism of catalpol.

KEY FINDINGS

In this study, we tested whether catalpol has the potential to improve skeletal insulin sensitivity by augmenting myogenesis, in which we found that, catalpol treatment in db/db mice lowered blood glucose and improved insulin sensitivity via activation of phosphatidylinositol‑3‑Kinase (PI3K)/protein kinase B (AKT) pathway. Moreover, catalpol-treated mice exhibited enhanced myogenesis, as evidenced by increased myogenic differentiation (MyoD), myogenin (MyoG) and myosin heavy chain (MHC) expressions. The in vitro experimental results showed that both catalpol and metformin enhanced glucose uptake via activation of PI3K/AKT pathway. However, unlike metformin, the PI3K/AKT pathway activation by catalpol was dependent on enhanced MyoD/MyoG-mediated myogenesis.

SIGNIFICANCE

Improvement of insulin sensitivity by enhancing MyoD/MyoG-mediated myogenesis may constitute a new therapeutic approach for treating type 2 diabetes.

Acute Whole Body Vibration Decreases the Glucose Levels in Elderly Diabetic Women

Type II diabetes (TIIDM) is characterized by high levels of blood glucose followed by excessive insulin release so that the target cells become less sensitive, developing insulin resistance and maintaining hyperglycemic levels. Physical activity is the strongest element to prevent and to manage the TIIDM, and the majority of patients do not remain in regularly active levels, because the premature fatigue in these patients decreases the adherence to the training. Contrastingly, the whole body vibration (WBV) training may improve the glucose metabolism in diabetic patients, reducing the peripheral blood sugar, decreasing the physical discomfort and perceived exertion. Therefore, the purpose of the study was to determine the effect of an acute WBV session as therapy to promote fasting decreases in insulin levels in peripheral blood in TIIDM when compared to healthy elderly. For this, fifteen healthy elderly women and fourteen diabetic elderly women, all sedentary, were allocated in diabetic or control groups, and we made an acute whole body session composed of 10 bouts lasting 2 minutes each one, separated by a 30-second rest period. The WBV was executed in a triaxial platform MY3 Power Plate® at 35 hertz and has been chosen a peak-to-peak displacement of 4 millimeters. After the protocol, both groups decreased the glycemic levels and increased lactate production in relation to the basal levels and when compared diabetic and control, where the most important results have been shown in diabetic women. This study revealed that WBV training in TIIDM has had significant beneficial effects on the control of glucose levels, still in an acute session. So that, the complete training probably will show better results about glycemic control and this finding could be especially important when prescribing exercise for elderly who are unable or unwilling to use traditional loads or who show poor exercise compliance.

The impact of type 1 diabetes and diabetic polyneuropathy on muscle strength and fatigability

AIMS

Although it is widely accepted that diabetic polyneuropathy (DPN) is linked to a marked decline in neuromuscular performance, information on the possible impact of type 1 diabetes (T1D) on muscle strength and fatigue remains unclear. The purpose of this study was to investigate the effects of T1D and DPN on strength and fatigability in knee extensor muscles.

METHODS

Thirty-one T1D patients (T1D), 22 T1D patients with DPN (DPN) and 23 matched healthy control participants (C) were enrolled. Maximal voluntary contraction (MVC) and endurance time at an intensity level of 50% of the MVC were assessed at the knee extensor muscles with an isometric dynamometer. Clinical characteristics of diabetic patients were assessed by considering a wide range of vascular and neurological parameters.

RESULTS

DPN group had lower knee extensor muscles strength than T1D (-19%) and the C group (-37.5%). T1D group was 22% weaker when compared to the C group. Lower body muscle fatigability of DPN group was 22 and 45.5% higher than T1D and C group, respectively. T1D group possessed a higher fatigability (29.4%) compared to C group. A correlation was found between motor and sensory nerve conduction velocity and muscle strength and fatigability.

CONCLUSIONS

Patients with T1D are characterised by both a higher fatigability and a lower muscle strength, which are aggravated by DPN. Our data suggest that factors other than nervous damage play a role in the pathogenesis of such defect.