Decreased stiffness at the ankle joint in patients with long-term Type 1 diabetes.
OBJECTIVE
To evaluate contractile and reflex properties of the soleus muscle together with ankle joint stiffness in long-term Type 1 patients.


METHODS
Stretch reflex and muscle function of the soleus muscle was tested in 15 Type 1 diabetes mellitus patients and 15 controls. M-wave amplitude and maximal twitch torque was elicited by supramaximal stimulation of the tibial nerve. The stretch reflex was elicited by a 4 degree rotation of the ankle.


RESULTS
Rise time and fall time of the maximal twitch torque were increased compared with controls. The amplitude of the short latency stretch reflex was significantly reduced in patients at contraction levels of 5-30 Nm. At a contraction level of 5 Nm the median stretch reflex threshold was 10 degrees/s in patients and 6 degrees/s in controls (P = 0.03). Stiffness was decreased in diabetic patients, especially at lower contraction levels. There was no significant correlation between the clinical neuropathy score and stiffness. In contrast, high neuropathy score was correlated with low amplitude of the reflex amplitude (rho = -0.51, P = 0.05).


CONCLUSIONS
We demonstrate altered contractile properties, a decrease in stretch reflex of the soleus muscle, and a reduced stiffness at the ankle joint in patients with long-term Type 1 diabetes. These changes may cause delayed muscle contraction and impaired reflex modulation which could contribute to gait disturbances and increased number of falls in diabetic patients.
Nielsen
J F
JF
Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark. neujfn@ss.aaa.dk
Andersen
H
H
Sinkjaer
T
T
D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology*; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D012026:Reflex, Stretch / Q000502:physiology