Insulin resistance is associated with an exaggerated blood pressure response to ischemic rhythmic handgrip exercise in non-diabetic older adults.

Patients with type 2 diabetes display an exaggerated pressor response to exercise. However, evidence supporting the association between the magnitude of the pressor response to exercise and insulin resistance-related factors including hemoglobin A1c (HbA1c) or homeostatic model assessment of insulin resistance (HOMA-IR) in non-diabetic subjects has remained sparse and inconclusive. Thus we investigated the relationship between cardiovascular responses to exercise and insulin resistance-related factors in non-diabetic healthy men (n=23) and women (n=22) above 60 years old. We measured heart rate (HR) and blood pressure (BP) responses during: isometric handgrip (IHG) exercise of 30% maximal voluntary contraction, a period of skeletal muscle ischemia (SMI) induced by tourniqueting the arm after IHG, and rhythmic dynamic handgrip (DHG) exercise during SMI. Greater diastolic BP (DBP) responses to DHG with SMI was associated with male-sex (r=0.44, P=0.02) and higher HbA1c (r=0.33, P=0.03), heart-ankle pulse wave velocity (haPWV) (r=0.45, P<0.01), and resting systolic BP (SBP) (r=0.36, P=0.02). HbA1c persisted as a significant determinant explaining the variance in the DBP response to DHG with SMI in multivariate models despite adjustment for sex, haPWV, and resting SBP. It was also determined that the DBP response to DHG with SMI in a group in which HOMA-IR was abnormal (Δ33±3 mmHg) was significantly higher than that of groups in which HOMA-IR was at intermediate (Δ20±4 mmHg) and normal (Δ23±2 mmHg) levels. These data suggest that even in non-diabetic older adults, insulin resistance is related to an exaggerated pressor response to exercise especially when performed under ischemic conditions.