Mechanisms for the increased fatigability of the lower limb in people with type 2 diabetes

Fatiguing exercise is the basis of exercise training and a cornerstone of management of type 2 diabetes mellitus (T2D); however, little is known about the fatigability of limb muscles and the involved mechanisms in people with T2D. The purpose of this study was to compare fatigability of knee extensor muscles between people with T2D and controls without diabetes and determine the neural and muscular mechanisms for a dynamic fatiguing task. Seventeen people with T2D [ten men and seven women: 59.6 (9.0) yr] and twenty-one age-, body mass index-, and physical activity-matched controls [eleven men and ten women: 59.5 (9.6) yr] performed one hundred twenty high-velocity concentric contractions (one contraction/3 s) with a load equivalent to 20% maximal voluntary isometric contraction (MVIC) torque with the knee extensors. Transcranial magnetic stimulation (TMS) and electrical stimulation of the quadriceps were used to assess voluntary activation and contractile properties. People with T2D had larger reductions than controls in power during the fatiguing task [42.8 (24.2) vs. 26.4 (15.0)%; P < 0.001] and MVIC torque after the fatiguing task [37.6 (18.2) vs. 26.4 (12.1)%; P = 0.04]. People with T2D had greater reductions than controls in the electrically evoked twitch amplitude after the fatiguing task [44.0 (20.4) vs. 35.4 (12.1)%, respectively; P = 0.01]. However, the decrease in voluntary activation was similar between groups when assessed with electrical stimulation [12.1 (2.6) vs. 12.4 (4.4)% decrease; P = 0.84] and TMS ( P = 0.995). A greater decline in MVIC torque was associated with larger reductions of twitch amplitude ( r2 = 0.364, P = 0.002). Although neural mechanisms contributed to fatigability, contractile mechanisms were responsible for the greater knee extensor fatigability in men and women with T2D compared with healthy controls. NEW & NOTEWORTHY Transcranial magnetic stimulation and percutaneous muscle stimulation were used to determine the contributions of neural and contractile mechanisms of fatigability of the knee extensor muscles after a dynamic fatiguing task in men and women with type 2 diabetes (T2D) and healthy age-, body mass index-, and physical activity-matched controls. Although neural and contractile mechanisms contributed to greater fatigability of people with T2D, fatigability was primarily associated with impaired contractile mechanisms and glycemic control.

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Abstract P057: Clusters of Cardiovascular Risk Factors Predict Incidence of Type 2 Diabetes in Men and Women: A Swedish Population-based Study

Circulation ◽

10.1161/circ.133.suppl_1.p057 ◽

2016 ◽

Vol 133 (suppl_1) ◽

Author(s):

Charlotte A Larsson ◽

Bledar Daka ◽

Margareta I Hellgren ◽

Maria C Eriksson ◽

Lennart Råstam ◽

...

Keyword(s):

Physical Activity ◽

Risk Factors ◽

Type 2 Diabetes ◽

Cardiovascular Risk ◽

Cardiovascular Risk Factors ◽

Population Based ◽

Population Based Study ◽

Men And Women ◽

Self Rated Health

Introduction: Clusters of metabolic variables and their effects on incidence of type 2 diabetes have been studied previously; however, little is known about the effects on diabetes from risk factor clusters including lifestyle and self-rated health. Hypothesis: We assessed the hypothesis that clusters of common cardiovascular risk factors, including lifestyle and self-rated health, can predict development of type 2 diabetes in men and women, respectively. Methods: In 2002-2005, 2816 men and women, 30-74 years, were randomly selected from two municipalities in southwestern Sweden and assessed with regard to cardiovascular/metabolic risk factors within the Skaraborg Project (76% participation). Participants performed an OGTT, had blood samples drawn, had anthropometric measurements and blood pressure taken, and answered validated questionnaires about e.g. leisure-time physical activity (with four answer alternatives from intensive to sedentary) and self-rated health (with five alternatives from excellent to very poor). Using the same protocol, 1332 participants from the baseline survey where re-examined in 2011-2014. After excluding those with diabetes at baseline, 1268 participants were included in this prospective population-based study. Results: Factor analysis (using varimax rotation) identified significant loadings (≥0.40) on the following three identical factors in men and women: the metabolic factor , comprising HOMA-ir, WHR, systolic blood pressure, and apolipoprotein B-to-A1 ratio; the vitality factor , comprising physical activity and self-rated health; and the addiction factor , comprising smoking and alcohol consumption. After a mean follow-up of 9.7±1.4 years, 76 cases of diabetes were identified; 46 in men and 30 in women. In a logistic regression analysis adjusted for all principal components, age, and educational level, the metabolic factor significantly predicted type 2 diabetes in both men (OR: 3.3, CI: 2.3-5.0) and women (OR: 3.5, CI: 2.2-5.6). Furthermore, a predictive effect of the vitality factor was also seen in women (OR: 1.8, CI: 1.2-2.9), but not in men (OR: 1.1, CI: 0.8-1.6), whereas the addiction factor had no effect in either men or women. Conclusions: This is to our knowledge the first time principle components of cardiovascular risk factors, including both metabolic and lifestyle variables, have been used to predict incidence of type 2 diabetes. The gender difference observed with regard to the combined impact of self-rated health and physical activity are novel and indicates a mechanism beside the metabolic syndrome that warrants further gender-specific exploration in future studies.

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Exercise-induced hyperemia is associated with knee extensor fatigability in adults with type 2 diabetes

Journal of Applied Physiology ◽

10.1152/japplphysiol.00854.2018 ◽

2019 ◽

Vol 126 (3) ◽

pp. 658-667 ◽

Cited By ~ 5

Author(s):

Jonathon W. Senefeld ◽

Jacqueline K. Limberg ◽

Kathleen M. Lukaszewicz ◽

Sandra K. Hunter

Keyword(s):

Type 2 Diabetes ◽

Blood Flow ◽

Lower Limb ◽

Contractile Function ◽

Muscle Blood Flow ◽

Knee Extensor ◽

Dynamic Exercise ◽

Extensor Muscles ◽

Exercise Induced

The aim of this study was to compare fatigability, contractile function, and blood flow to the knee extensor muscles after dynamic exercise in patients with type 2 diabetes mellitus (T2DM) and controls. The hypotheses were that patients with T2DM would demonstrate greater fatigability than controls, and greater fatigability would be associated with a lower exercise-induced increase in blood flow and greater impairments in contractile function. Patients with T2DM ( n = 15; 8 men; 62.4 ± 9.0 yr; 30.4 ± 7.7 kg/m2; 7,144 ± 3,294 steps/day) and 15 healthy control subjects (8 men, 58.4 ± 6.9 yr; 28.4 ± 4.6 kg/m2; 7,893 ± 2,323 steps/day) were matched for age, sex, body mass index, and physical activity. Fatigability was quantified as the reduction in knee extensor power during a 6-min dynamic exercise. Before and after exercise, vascular ultrasonography and electrical stimulation were used to assess skeletal muscle blood flow and contractile properties, respectively. Patients with T2DM had greater fatigability (30.0 ± 20.1% vs. 14.6 ± 19.0%, P < 0.001) and lower exercise-induced hyperemia (177 ± 90% vs. 194 ± 79%, P = 0.04) than controls but similar reductions in the electrically evoked twitch amplitude (37.6 ± 24.8% vs. 31.6 ± 30.1%, P = 0.98). Greater fatigability of the knee extensor muscles was associated with postexercise reductions in twitch amplitude ( r = 0.64, P = 0.001) and lesser exercise-induced hyperemia ( r = −0.56, P = 0.009). Patients with T2DM had greater lower-limb fatigability during dynamic exercise, which was associated with reduced contractile function and lower skeletal muscle blood flow. Thus, treatments focused on enhancing perfusion and reversing impairments in contractile function in patients with T2DM may offset lower-limb fatigability and aid in increasing exercise capacity. NEW & NOTEWORTHY Although prior studies compare patients with type 2 diabetes mellitus (T2DM) with lean controls, our study includes controls matched for age, body mass, and physical activity to more closely assess the effects of T2DM. Patients with T2DM demonstrated no impairment in macrovascular endothelial function, evidenced by similar flow-mediated dilation to controls. However, patients with T2DM had greater fatigability and reduced exercise-induced increase in blood flow (hyperemia) after a lower-limb dynamic fatiguing exercise compared with controls.

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Clinical Measures of Physical Fitness Predict Insulin Resistance in People at Risk for Diabetes

Physical Therapy ◽

10.2522/ptj.20080064 ◽

2008 ◽

Vol 88 (11) ◽

pp. 1355-1364 ◽

Cited By ~ 31

Author(s):

Chiao-Nan Chen ◽

Lee-Ming Chuang ◽

Ying-Tai Wu

Keyword(s):

Physical Activity ◽

Insulin Resistance ◽

Type 2 Diabetes ◽

Body Mass Index ◽

At Risk ◽

Risk Factor ◽

Waist Circumference ◽

Physical Fitness ◽

Clinical Measures

Background and Purpose Physical inactivity has been well documented as a risk factor for type 2 diabetes. Previous studies measured the level of physical activity either with questionnaires or with direct measurements of maximum oxygen uptake. However, questionnaires are patient-report measures, and methods for obtaining direct maximum oxygen uptake measurements often are not available clinically. The purpose of this study was to investigate whether clinical measurement of health-related physical fitness with a simple test battery can predict insulin resistance, a precursor of type 2 diabetes, in people at risk for diabetes. Subjects and Methods A total of 151 volunteers with at least one diabetes risk factor (overweight, hypertension, dyslipidemia, family history, impaired glucose tolerance, gestational diabetes, or delivering a baby weighing more than 4.0 kg) were recruited. Insulin resistance (as determined with the homeostasis model assessment of insulin resistance [HOMA-IR]), physical fitness (including body composition, as determined with the body mass index and waist circumference), muscle strength (handgrip strength [force-generating capacity]), muscle endurance (sit-up test), flexibility (sit-and-reach test), and cardiorespiratory endurance (step test) were measured, and a physical activity questionnaire was administered. Backward regression analysis was used to build the prediction models for insulin resistance from components of physical fitness and physical activity. Results Body mass index, muscle strength, and cardiorespiratory fitness predicted HOMA-IR in men (adjusted R2=.264). In women, age, waist circumference, and cardiorespiratory fitness were the predictors of HOMA-IR (adjusted R2=.438). Discussion and Conclusion Clinical measures of physical fitness can predict insulin resistance in people at risk for diabetes. The findings support the validity of clinical measures of physical fitness for predicting insulin resistance in people at risk for diabetes.

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