The Impact of Exercise Timing on Glycemic Control: A Randomized Clinical Trial

Shaun Y. M. Teo, Jill A. Kanaley, Kym J. Guelfi, Kieran J. Marston, Timothy J. Fairchild

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42 Citations (Scopus)
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Despite the acknowledgement of exercise as a cornerstone in the management of Type 2 Diabetes (T2D), the importance of exercise timing has only recently been considered.

PURPOSE: This study sought to determine the effect of diurnal exercise timing on glycemic control in individuals enrolled in a 12-week supervised multi-modal exercise training program. A secondary aim was to determine the effect of diurnal exercise timing on the circadian rhythm of wrist skin temperature.

METHODS: Forty sedentary, overweight adults (age: 51[SD 13]years; BMI: 30.9[SD 4.2]kg/m; women: n=23) with and without (n=20) T2D diagnosis were randomly allocated to either a morning (amEX) or evening (pmEX) exercise training group. The supervised 12-week (3 days/week) program, comprised 30 minutes of moderate intensity walking and 4 resistance-based exercises (3 sets, 12-18 repetitions each). Glycemic outcomes (glycated haemoglobin, HbA1c; fasting glucose, FG; postprandial glucose, PPG) wrist skin temperature were assessed at baseline and post-intervention.

RESULTS: Exercise training improved (main effect of time: all p<0.01) all glycemic outcomes, however, this was independent of allocation to either the amEX (Hedge's g: 0.23-0.90) or pmEX (Hedge's g: 0.16-0.90) group. Accordingly, the adopted exercise training program did not alter the circadian rhythm of skin temperature. When only T2D individuals were compared, amEX demonstrated greater effects (all Hedge's g) on HbA1c (amEX: 0.57; pmEX: 0.32), FG (amEX: 0.91; pmEX: 0.53) and PPG (amEX: 1.12; pmEX: 0.71) but was not statistically different.

CONCLUSIONS: Twelve weeks of multi-modal exercise training improved glycemic control and postprandial glycemic responses in overweight non-T2D and T2D individuals. However, no distinct glycemic benefits or alterations in circadian rhythm were associated with morning versus evening exercise, when performed three times per week in this cohort.


Original languageEnglish
Pages (from-to)323-334
Number of pages12
JournalMedicine and Science in Sports and Exercise
Issue number2
Early online date30 Aug 2019
Publication statusPublished - 1 Feb 2020


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