The effects of free-living interval-walking training on glycemic control, body composition, and physical fitness in type 2 diabetic patients: a randomized, controlled trial

Abstract

Objective: To evaluate the feasibility of free-living walking training in type 2 diabetic patients and to investigate the effects of interval-walking training versus continuous-walking training upon physical fitness, body composition, and glycemic control.

Research design and methods: Subjects with type 2 diabetes were randomized to a control (n = 8), continuous-walking (n = 12), or interval-walking group (n = 12). Training groups were prescribed five sessions per week (60 min/session) and were controlled with an accelerometer and a heart-rate monitor. Continuous walkers performed all training at moderate intensity, whereas interval walkers alternated 3-min repetitions at low and high intensity. Before and after the 4-month intervention, the following variables were measured: VO(2)max, body composition, and glycemic control (fasting glucose, HbA(1c), oral glucose tolerance test, and continuous glucose monitoring [CGM]).

Results: Training adherence was high (89 ± 4%), and training energy expenditure and mean intensity were comparable. VO(2)max increased 16.1 ± 3.7% in the interval-walking group (P < 0.05), whereas no changes were observed in the continuous-walking or control group. Body mass and adiposity (fat mass and visceral fat) decreased in the interval-walking group only (P < 0.05). Glycemic control (elevated mean CGM glucose levels and increased fasting insulin) worsened in the control group (P < 0.05), whereas mean (P = 0.05) and maximum (P < 0.05) CGM glucose levels decreased in the interval-walking group. The continuous walkers showed no changes in glycemic control.

Conclusions: Free-living walking training is feasible in type 2 diabetic patients. Continuous walking offsets the deterioration in glycemia seen in the control group, and interval walking is superior to energy expenditure-matched continuous walking for improving physical fitness, body composition, and glycemic control.

Trial registration: ClinicalTrials.gov NCT01234155.

Figure 1

Subjects with type 2 diabetes were randomized to a CON (white bars), CWT (striated bars), or IWT group (black bars). Aerobic fitness (VO₂max) (A), body mass (B), whole-body fat mass (dual-energy X-ray absorptiometry) (C), and abdominal visceral adiposity (MRI) (D) were measured at baseline and after 4 months. Data are presented as mean Δ values (post − preintervention values) ± SEM. Statistical differences were analyzed by two-way repeated-measures ANOVA when comparing pre to post changes within groups (indicated by ***P < 0.001), and one-way ANOVA of Δ values when comparing differences between groups (indicated by a connecting line between bars; *P < 0.05 and **P < 0.01).

Figure 2

Subjects with type 2 diabetes were randomized to a CON (white bars), CWT (striated bars), or IWT group (black bars). Intervention-induced changes in glycemic control were assessed by examining post − preintervention changes in the following variables: mean 48-h CGM glucose (A), minimum 48-h CGM glucose (B), and maximum 48-h CGM glucose (C). Data are presented as mean Δ values (post − preintervention values) ± SEM. Statistical differences were analyzed by two-way repeated-measures ANOVA when comparing pre to post changes within groups (indicated by *P < 0.05 and **P < 0.01), and one-way ANOVA of Δ values when comparing differences between groups (indicated by a connecting line between bars; **P < 0.01).