Comparative evaluation of the locomotor pattern of activities of daily living in diabetic neuropathic subjects through surface EMG and kinematics

The diabetic neuropathy is one of the main chronic complications of Diabetes Mellitus which causes damage to somatosensory and motor control systems resulting in biomechanical alterations in locomotion patterns. Locomotion activities with greater mechanical and balance demands might be considered a risk factor for ulcer formation in diabetic neuropathic patients. Therefore, to have a better understanding of the diabetic neuropatic interference in the daily life of these individuals, it is essential to evaluate the biomechanics of lower limbs during real life activities. The aim of this study was to investigate the influence of the diabetic neuropathy in the discrete characteristics and in time series of muscle activation patterns, using superficial EMG, and sagittal kinematics, using electrogoniometers, of lower limbs during stair management in diabetics (n=23) and non-diabetic individuals (n=23). The discrete analyses were done by discrete variables of VL, GM and TA linear envelopes and the sagittal angular variation of hip, knee and ankle. These variables were compared between groups in each motor task, by t test for independent samples ( = 0.05). The analyses of electromyographic and sagittal angular variation time series were performed by cross-correlation of each serie between groups. Moreover, the strength of the phase relationship between muscle activity of VL, TA and GM with the angular variation of knee and ankle was assessed in each group. The correlation coefficients of these relationships were compared between groups by independent t tests ( = 0.05). The main findings showed that during the stair ascent, diabetics had lower ankle extension at the end of stance phase, and while projecting their body forward during the first half of stance, their ankle flexion angle was also smaller. Because of that, there was a worse ankle positioning in the beginning of the stance, necessary for an efficient action of VL. The mechanical disadvantage of VL observed in diabetic neuropathic patients at the beginning of the stance phase may have triggered an increased activation in the same muscle at the end of stance in the contralateral leg. In the stair descent, diabetics had lower ankle extension at the beginning of stance, but did not show significant alterations in EMG. In the time series analysis, the EMG signals of all muscles presented higher similarities in timing across time series between groups for stair ascent and descent. The correlation obtained between groups for the muscle activity and angular variation amongst all evaluated relationships were statistically lower in the diabetic group for stair ascent (for VL-knee and GM-ankle (both groups presented weak relation), except for the relation between TA and ankle joint variation, which was moderate for the diabetic individuals and weak for controls. In the stair descent, the correlations were similar between groups (moderate relation for VL- knee and GM - ankle, and a weak relation for TA - ankle). Apparently, the stair ascent explicited motor deficits caused by diabetic neuropathy in the discrete analysis and also in the time series analysis. Although the similarities in the time series in the stair descent, qualitative shape differences were observed, suggesting a impaired pattern of motor recruitment in neuropathic patients. In summary, diabetic neuropathic individuals presented an altered ankle kinematic and VL and TA muscles activities patterns during these real life activities, and also altered coordination between muscle activity of knee and ankle and adjacent joint motion. These facts, combined to higher vertical impacts of stair ascent and descent might raise the plantar ulceration risks in the daily activities of diabetic neuropathic individuals (AU)