The effects of different accumulated pressure-time integral stimuli on plantar blood flow in people with diabetes mellitus

Yih-Kuen Jan,Wenqiang Ye,Weiyan Ren,Fang Pu,Yijie Duan,Liqiang Xu

doi:10.1186/s12891-021-04437-9

Abstract

BackgroundExercise, especially weight-bearing exercise (e.g. walking), may affect plantar tissue viability due to prolonged repetitive high vertical and high shear pressure stimulus on the plantar tissue, and further induce development of diabetic foot ulcers (DFUs). This study aimed to investigate the effects of different accumulated pressure-time integral (APTI) stimuli induced by walking on plantar skin blood flow (SBF) responses in people with diabetes mellitus (DM).MethodsA repeated measures design was used in this study. Two walking protocols (low APTI (73,000 kPa·s) and high APTI (73,000 × 1.5 kPa·s)) were randomly assigned to ten people with DM and twenty people without DM. The ratio of SBF measured by laser Doppler flowmetry after walking to that before (normalized SBF) was used to express the SBF responses.ResultsAfter low APTI, plantar SBF of people with DM showed a similar response to people without DM (P = 0.91). However, after high APTI, people with DM had a significantly lower plantar SBF compared to people without DM (P < 0.05). In people with DM, plantar SBF in the first 2 min after both APTI stimuli significantly decreased compared to plantar SBF before walking (P < 0.05).ConclusionsPeople with DM had a normal SBF response after low APTI walking but had an impaired SBF response after high APTI walking, which suggests that they should avoid weight-bearing physical activity with intensity more than 73,000 kPa·s and should rest for more than 2 min after weight-bearing physical activity to allow a full vasodilatory response to reduce risk of DFUs.

Highlights

Exercise, especially weight-bearing exercise, may affect plantar tissue viability due to prolonged repetitive high vertical and high shear pressure stimulus on the plantar tissue, and further induce development of diabetic foot ulcers (DFUs)
A repeated measures design was used in this study to analyse the effects of different accumulated pressure-time integral (APTI) stimuli induced by walking on plantar skin blood flow responses in people with and without diabetes
The results showed that normalized skin blood flow (SBF) of people with diabetes mellitus (DM) was significantly lower than that of healthy participants after the high APTI stimulus but not after the low APTI stimulus, which indicates that people with DM may have an impaired blood flow response under the high APTI stimulus

Summary

Introduction

Especially weight-bearing exercise (e.g. walking), may affect plantar tissue viability due to prolonged repetitive high vertical and high shear pressure stimulus on the plantar tissue, and further induce development of diabetic foot ulcers (DFUs). Wu et al demonstrated that faster walking speeds (i.e. 6 and 9 km/h) could significantly increase plantar skin blood flow within the same duration, and concluded that faster walking speeds should be suggested for people with DM for improving microvascular function [13]. Burnfield et al showed that faster walking speeds increased plantar pressure at the toes, medial metatarsal heads and heel [14] It indicates that the diabetic plantar tissue may be subjected to a high level of cumulative pressure during the repetitive high stress (faster walking) over the same duration, which has been considered to negatively affect the plantar blood perfusion and plantar tissue viability [5, 15,16,17]. It is crucial to further explore the response of plantar microcirculation to different amounts of cumulative pressure, which will help to further clarify the degree of foot ulcer risk when pursuing various exercise with different accumulated pressure stimuli in people with DM [5, 18]

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