Muscle synergies are largely unaffected in individuals with diabetes who do not have diabetic neuropathy

Background

Impaired neuromuscular function in individuals with diabetes can adversely affect gait kinematics, kinetics, and electromyography, potentially increasing the risk of serious complications such as plantar ulcers and amputations. However, it remains unclear whether these changes are associated with alterations in muscle synergies. This study aims to examine muscle synergies in individuals with diabetes.

Methods

Surface electromyography recordings were obtained from seven lower extremity muscles (vastus lateralis, rectus femoris, biceps femoris, semitendinosus, lateral gastrocnemius, soleus, and tibialis anterior) during 20 trials of barefoot walking. Eleven individuals with type 2 diabetes without diabetic neuropathy and ten age-matched controls were recruited. Variations in synergy complexity were assessed by the number of synergies needed to account for >90 % of the total variance in the electromyography data, total variance accounted for by one synergy, and total variance accounted for by four synergies. Synergy weights and activations for a four-synergy solution were compared using cosine similarity. An electromyography co-contraction index was computed for agonist and antagonist pairs of muscles.

Findings

Those with diabetes did not significantly differ from controls in the number of synergies, total variance accounted for by one synergy, total variance accounted for by four synergies, or synergy composition. However, they demonstrated higher levels of variability in synergy composition similarity.

Interpretation

These results indicate that, at the group level, individuals with diabetes without neuropathy employ largely similar motor control strategies as their healthy counterparts while walking, and previously reported variations in gait biomechanics in this population may be attributed to peripheral neuromuscular dysfunction.