Effects of different exercise programmes on ankle stiffness, muscle strength, and plantar pressure distribution in individuals with type 2 diabetes mellitus and peripheral neuropathy: a single-blind randomised controlled trial

BACKGROUND: Diabetic peripheral neuropathy impairs plantar sensation and disrupts foot and ankle biomechanics, thereby increasing the risk of foot ulceration. This study aimed to compare the effects of different exercise interventions on ankle stiffness, ankle muscle strength, plantar pressure distribution and vibration perception threshold (VPT) in individuals with type 2 diabetes mellitus (T2D) and diabetic peripheral neuropathy (DPN). METHODS: Seventy-four participants with T2D and DPN were randomised into three groups: a control group (CG) receiving standard medical treatment; an aerobic exercise group (AEG) receiving medical treatment plus supervised treadmill training three times per week; and a combined exercise group (AE+FAEG) performing additional targeted foot and ankle exercises following each aerobic session. Custom-made foot orthoses were provided to all participants. Ankle stiffness, isokinetic muscle strength, plantar pressure distribution, vibration perception threshold (VPT), and glycaemic parameters were assessed at baseline, Week 12, and Week 24. Data were analysed using two-way repeated measures ANOVA to evaluate Group × Time interactions. RESULTS: Significant Group × Time interactions were observed for ankle stiffness (p < 0.001, η²p = 0.35), muscle strength (p < 0.001, η²p = 0.19-0.48), forefoot-to-rearfoot pressure ratio (p < 0.001, η²p = 0.31), VPT (p < 0.001, η²p = 0.51-0.52), and glycaemic parameters (p < 0.05, η²p = 0.10-0.24). Compared with the CG, both exercise groups improved over time, with greater gains in the AE+FAEG. While within-group reductions in plantar pressure were observed across all groups (p < 0.001), between-group differences were not consistently detected. CONCLUSIONS: The integration of targeted foot and ankle exercises into a supervised aerobic programme was associated with meaningful improvements in ankle stiffness and muscle strength in individuals with T2D and DPN. Both exercise modalities were associated with improvements in glycaemic parameters, with the combined intervention demonstrating superior functional benefits compared with standard care. These findings support the inclusion of combined exercise strategies in rehabilitation programmes targeting biomechanical and metabolic impairments associated with diabetic foot complications. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05422235. Registered 13 June 2022 (Prospectively registered).