Oral Presentation Australian and New Zealand Obesity Society Annual Scientific Conference 2023

Skeletal muscle microvascular blood flow is increased for up to 30 minutes post-maximal aerobic exercise in individuals with pre-diabetes or type 2 diabetes (97630)

Lewan Parker 1 2 , Hannah J Thomas 2 , Kimberley L Way 1 2 3 , Mark Nolan 1 , Ralph Maddison 2 , Tom H Marwick 1 , Michelle A Keske 1 2
  1. Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
  2. Institute for Physical Activity and Nutrition (IPAN), Deakin University, Geelong, Victoria, Australia
  3. Exercise Physiology and Cardiovascular Health Lab, University of Ottawa, Ottawa, Ontario, Canada

Introduction. Skeletal muscle microvascular blood flow has been identified as a factor contributing to exercise capacity, metabolism, and recovery in humans. However, few studies have directly measured skeletal muscle microvascular blood flow responses following aerobic exercise in individuals that often exhibit microvascular health complications such as those with type 2 diabetes. We therefore aimed to measure the effect of maximal aerobic exercise on skeletal muscle microvascular blood flow in individuals with pre-diabetes/type 2 diabetes using contrast enhanced ultrasound.

Methods. Thirteen adults with pre-diabetes/type 2 diabetes (age: 61.1 ± 8.0 years [M ± SD]; BMI: 32.2 ± 6.6 kg/m2; HbA1C: 6.61 ± 0.89%; 12 females and 1 male) attended the laboratory after a 2-hour fast and completed a Modified Bruce treadmill exercise test until exhaustion. Microvascular blood volume, velocity, and flow in the vastus lateralis muscle were assessed at rest, immediately post-exercise, and 30 minutes post-exercise via contrast enhanced ultrasound (iU22, Philips) during a constant-rate intravenous contrast agent infusion (DEFINITY®). Participants also completed a six-minute walk test.

Results. Microvascular blood velocity, volume, and flow increased immediately after exercise (~240%, ~62%, and ~433% increase, respectively; all p < 0.001), and remained elevated above baseline levels 30 minutes post-exercise (~80%, ~31%, and ~133% increase, respectively; all p ≤ 0.005). Skeletal muscle microvascular blood flow measures were not associated with VO2peak (ml/min/kg), time to exhaustion, or six-minute walk distance (all p > 0.05).

Conclusion. Skeletal muscle microvascular blood flow is elevated for up to 30 minutes post-maximal aerobic exercise in individuals with pre-diabetes/type 2 diabetes. The lack of association between microvascular blood flow and exercise capacity is not clear but may involve considerable blood flow redundancy within the vascular network previously reported with exercise. Further analysis in a larger cohort is required to understand the link between microvascular blood flow and exercise capacity.