Slower conduction velocity and motor unit discharge frequency are associated with muscle fatigue during isometric exercise in type 1 diabetes mellitus

Abstract

Type 1 diabetes mellitus (T1DM) is associated with a peripheral neuropathy that reduces nerve conduction velocity. This may impair high motor-unit discharge frequencies (MUDF), decrease muscle activation, and curtail the ability to sustain repetitive contractile tasks. We examined (1) whether MUDF, the contractile properties of the knee extensors, and the conduction velocity of persons with T1DM differed from controls; (2) whether persons with T1DM can maintain adequate MUDF during a fatigue protocol; and (3) the relationship between these parameters and impaired glycemic control. We studied male and female subjects with T1DM and controls matched for age, height, weight, and gender. Single motor unit recordings were made from vastus lateralis during maximal and submaximal contractions and during a fatigue protocol. Glycemic control was assessed from blood glucose concentration and glycosylated hemoglobin (HbA1c). Control femoral conduction velocities were comparable to literature values and those of the T1DM subjects were slower. These values correlated with plasma glucose and HbA1c. T1DM subjects fatigued 45% sooner than controls, and time to fatigue and conduction velocity were correlated (r = 0.54, P < 0.05). Discharge frequencies tended to be slower during 50% maximal voluntary contractile force in the T1DM subjects at task failure. Persons with T1DM had slower conduction velocities and lower MUDF than their controls, which apparently leads to impaired activation of muscle and decreased endurance during isometric fatigue.

Declining Skeletal Muscle Function in Diabetic Peripheral Neuropathy

“…49 Declines in femoral nerve conduction have also been reported in diabetic patients without overt signs of neuropathy. 50 The slower conduction velocities may be linked to enhanced muscle fatigue with DPN. Slower femoral nerve conduction velocities are also associated with higher blood glucose.…”

Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients

“…10 MFCV depends, among other factors, on sarcolemmal excitability (Arendt-Nielsen 11 and Zwarts 1989; Linssen et al 1996;Chisari et al 1998), morphological and 12 functional characteristics of muscle fibers (Arendt-Nielsen and Zwarts 1989; Kupa et 13 al. 1995;Almeida et al 2008) and can be influenced by changes in neuromuscular 14 recruitment strategies occurring independently of motor nerve dysfunction (Sacchetti 15 et al, 2013). In particular, the T2D patients involved in the present study did not 16 present clinical signs of neuropathy and their median duration of diabetes was very 17 short, so it may be plausible that their baseline MFCV values were not much different 18 from the ones of healthy subjects.…”

“…The number of studies investigating muscle endurance in 14 relation with diabetes is limited (Andersen 1998;Almeida et al 2008;Shah et al 15 2011;Ijzerman et al 2012) and the results are conflicting partially due to the different 16 testing procedure adopted (isometric vs concentric contractions), the limb tested 17 (upper vs lower) and the diabetic population (type 1 vs type 2) considered. 18…”

“…More information, however, is needed 25 on the effects of exercise training on the torque-angular velocity relationship, which 26 reflects the fundamental mechanisms of force generation during different contractile 27 tasks (Larsson et al, 1979). Similarly, muscle endurance, another important 28 determinant of performance during functional task/activities of daily living, has been 29 poorly explored in relation with diabetes, with the few investigations performed 1 leading to conflicting results (Almeida et al, 2008;Andersen et al, 2005;Andersen, 2 1998;Fritschi & Quinn, 2010). The use of surface electromyography (EMG), a non-3 invasive measure of myoelectric activity, allows a greater understanding of the 4 activation patterns of the muscle of interest.…”

Decreased Satellite Cell Number and Function in Humans and Mice With Type 1 Diabetes Is the Result of Altered Notch Signaling

“…Although skeletal muscle is a largely resilient tissue that is capable of adapting to changing conditions, the skeletal muscle of individuals with T1D exhibits a decline in physiological function and performance compared with healthy skeletal muscle, including significant impairments to its reparative capacities (2)(3)(4)(5)(6)(7).…”