Exercise not only benefits physical and cardiovascular function in older adults with multiple chronic conditions, but may also improve cognitive function. Peak heart rate (HR), a physiological indicator for maximal effort, is the most common and practical means of establishing and monitoring exercise intensity. In particular, in the absence of graded maximal exercise tests (GXT) results, age-predicted maximal HR values are typically used. Using individuals with stroke as a model for examining older adults with co-existing cardiovascular and neuromotor conditions, the purpose of this paper was to examine the determinants associated with achieving age-predicted maximal HR on a GXT, with respect to neurological, cognitive and lower limb function.

Forty-seven participants with stroke (mean±SD age 67±7 years, 4±3 years post-stroke) performed GXTs. Peak values for gas exchange, HR and ratings of perceived exertion were noted. Logistic regression analysis was performed to examine determinants (neurological impairment, leg motor impairment, Montreal Cognitive Assessment (MoCA) score, walking ability) associated with the ability to achieve age-predicted maximal HR on the GXT.

VO₂peak was 16.5±6 ml•kg⁻¹•min⁻¹. Fourteen (30%) participants achieved ≥ 100% of age-predicted maximal HR. Logistic regression modeling revealed that the ability to achieve this threshold was associated with less leg motor impairment (P=0.02, OR 2.3) and higher cognitive scores (P=0.048, OR 1.3).

These results suggest that non-cardiopulmonary factors such as leg motor impairment and cognitive function are important contributors to achieving maximal effort during exercise tests. This study has important implications for post-stroke exercise prescription whereby training intensities that are based on peak HR from GXTs may be underestimated among individuals with cognitive and physical impairments.