Determinants of VO2peak responsiveness to aerobic exercise training in adults with Type 2 diabetes: the PROTECTION...

In individuals with Type 2 diabetes (T2D), aerobic exercise training improves cardiorespiratory fitness (VO2peak), a key determinant of cardiovascular risk and mortality. However, substantial interindividual variability exists in VO2peak responsiveness, and its determinants remain poorly characterized.

A total of 108 adults with T2D participated in a 26-week supervised, high-volume, moderate-intensity cycling programme (three sessions/week). VO2peak was assessed by cardiopulmonary exercise testing pre- and post-intervention. Based on the individual technical error of measurement (mean: 1.3 mL/kg/min) and the minimal clinically important difference (3.5 mL/kg/min), participants were divided into three groups: non-responder (n = 14), responders (n = 33), and high-responders (n = 41). Baseline demographic, clinical characteristics, as well as physical activity and sedentary behaviour were compared. Determinants of change in VO2peak were identified using univariate and multivariable LASSO regression analyses. Eighty-eight participants completed the exercise programme (59.8 ± 9.2 years, 64% male). VO2peak improved by +3.6 ± 2.5 mL/kg/min (+17%). Compared with non-responders, high-responders exhibited lower fat mass, lower insulin resistance, and lower baseline fitness. Changes in VO2peak were negatively associated with female sex, smoking status, anthropometric measures, insulin resistance, and beta-blocker or GLP-1 agonist use. In contrast, positive associations were found with lung function, muscle strength, and haemoglobin. In multivariable regression, fat mass (%) and insulin resistance emerged as key baseline predictors for VO2peak responsiveness.

A 26-week moderate-intensity cycling programme improved VO2peak in adults with T2D, although responses varied widely. Initiating exercise early after diagnosis of (pre)diabetes, along with interventions improving body composition, may enhance improvements in cardiorespiratory fitness.