The effect of exercise on neuropathic symptoms, nerve function, and cutaneous innervation in people with diabetic peripheral neuropathy

Abstract

Although exercise can significantly reduce the prevalence and severity of diabetic complications, no studies have evaluated the impact of exercise on nerve function in people with diagnosed diabetic peripheral neuropathy (DPN). The purpose of this pilot study was to examine feasibility and effectiveness of a supervised, moderately intense aerobic and resistance exercise program in people with DPN. We hypothesized that the exercise intervention can improve neuropathic symptoms, nerve function, and cutaneous innervation.

Methods: A pre-test post-test design was used to assess change in outcome measures following participation in a 10-week aerobic and strengthening exercise program. Seventeen subjects with diagnosed DPN (8 males/9 females; age 58.4±5.98; duration of diabetes 12.4±12.2 years) completed the study. Outcome measures included pain measures (visual analog scale), Michigan Neuropathy Screening Instrument (MNSI) questionnaire of neuropathic symptoms, nerve function measures, and intraepidermal nerve fiber (IENF) density and branching in distal and proximal lower extremity skin biopsies.

Results: Significant reductions in pain (-18.1±35.5 mm on a 100 mm scale, P=.05), neuropathic symptoms (-1.24±1.8 on MNSI, P=.01), and increased intraepidermal nerve fiber branching (+0.11±0.15 branch nodes/fiber, P=.008) from a proximal skin biopsy were noted following the intervention.

Conclusions: This is the first study to describe improvements in neuropathic and cutaneous nerve fiber branching following supervised exercise in people with diabetic peripheral neuropathy. These findings are particularly promising given the short duration of the intervention, but need to be validated by comparison with a control group in future studies.

Trial registration: ClinicalTrials.gov NCT00970060.

Conflict of interest statement

The authors have no conflict of interest to disclose.

Copyright © 2012 Elsevier Inc. All rights reserved.

Figures

Figure 1

Individual change in neuropathic symptom scores using the Michigan Neuropathy Screening Instrument questionnaire. Pre-intervention measures are labeled as #1 and post-intervention measures are labeled as #2; exercise duration was 10 weeks.

Figure 2

Individual change in intraepidermal nerve fiber (IENF) branching at proximal biopsy site. Pre-intervention measures are labeled as #1 and post-intervention measures are labeled as #2; exercise duration was 10 weeks.

Figure 3

Increased cutaneous nerve fibers after exercise in an individual subject with DPN. PGP 9.5+ fibers (arrows) in the epidermis before (A) and after (B) 10 weeks of exercise. Scale bar equals 50 μm.