Introduction: Exercise not only benefits physical and cardiovascular function in older adults with multiple chronic conditions but may also improve cognitive function. Peak 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 test (GXT) results, age-predicted maximal HR values are typically used. Using individuals with stroke as a model for examining older adults with coexisting cardiovascular and neuromotor conditions, the purpose of this article was to examine the determinants associated with achieving age-predicted maximal HR on a GXT, with respect to neurological, cognitive, and lower limb function.
Methods: Forty-seven participants with stroke (age, 67 ± 7 yr; 4 ± 3 yr poststroke (mean ± SD)) performed GXT. The peak values for gas exchange, HR, and RPE were noted. Logistic regression analysis was performed to examine determinants (neurological impairment, leg motor impairment, Montreal Cognitive Assessment score, and walking ability) associated with the ability to achieve age-predicted maximal HR on the GXT.
Results: V˙O2peak 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; odds ratio, 2.3) and higher cognitive scores (P = 0.048; odds ratio, 1.3).
Conclusions: These results suggest that noncardiopulmonary 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 poststroke exercise prescription, whereby training intensities that are based on peak HR from GXT may be underestimated among individuals with cognitive and physical impairments.
1Department of Physical Therapy, University of British Columbia, Vancouver, BC, CANADA; 2GF Strong Rehabilitation Centre, Vancouver Coastal Health, Vancouver, BC, CANADA; 3International Collaboration on Repair Discoveries, Vancouver Coastal Health, Vancouver, BC, CANADA; 4Division of Cardiology, University of British Columbia, Vancouver, BC, CANADA; 5Vancouver General Hospital, Vancouver Coastal Health, Vancouver, BC, CANADA; and 6Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, BC, CANADA
Address for correspondence: Janice J. Eng, Ph.D., B.Sc.(PT/OT), Department of Physical Therapy, University of British Columbia, 212-2177 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3; E-mail: firstname.lastname@example.org.
Submitted for publication June 2012.
Accepted for publication October 2012.