Cardiac Rehabilitation of The Patient with Stroke

Prescribing Aerobic Exercise Intensity without a Cardiopulmonary Exercise Test Post Stroke: Utility of the Six-Minute Walk Test

BACKGROUND

The cardiopulmonary exercise test (CPET) is an established method for determining target exercise training intensity (ventilatory threshold [VAT]) and cardiovascular risk; unfortunately, CPET is not readily accessible to people post stroke. The objective of this study was to determine the utility of the 6-minute walk test (6MWT) as a less resource-intensive alternative to CPET for prescribing exercise intensity to people post stroke with motor impairments.

METHODS

Sixty participants (male, 71.7%; 13.5 ± 22.5 [mean ± standard deviation] months post stroke; age 64.5 ± 12.5 years, with a Chedoke-McMaster Stroke Assessment score of 4.9 ± .9 of the leg) underwent 6MWT, CPET, balance, strength, and cognition assessments.

RESULTS

6MWT heart rate (hr) was significantly lower than VAT-hr (92.3 ± 14.8 beats⋅min(-1) versus 99.8 ± 15.7 beats⋅min(-1), respectively, P < .001; correlation r = .7, P < .001). Bland-Altman analysis revealed that the 6MWT underestimated the VAT-hr by 7.7 ± 11.5%. The 95% confidence interval of the mean bias was large (14.8% and -30.3%), reflecting poor agreement, with 71.7% (n = 43) of the participants unable to reach a walking intensity at or above the VAT-hr. Lower oxygen uptake at the VAT (β = .655, P = .004), higher 6MWT-hr (β = 1.07, P = .01), and better balance (β = 1.128, P = .04) were associated with greater utility of the 6MWT for prescribing exercise.

CONCLUSIONS

The 6MWT-hr was not interchangeable with the target training VAT-hr determined by CPET. However, in combination with CPET, the 6MWT will indicate when deficits preclude walking alone as the primary exercise modality for optimizing cardiovascular fitness. Future studies to develop a less resource-intensive, multimodal alternative to the CPET for prescribing exercise are needed. A modality that minimizes the effect of stroke deficits, specifically poor balance, should be included.

Cardiovascular Health and Fitness After Stroke

Stroke patients have profound cardiovascular and muscular deconditioning, with metabolic fitness levels that are about half those found in age-matched sedentary controls. Physical deconditioning, along with elevated energy demands of hemiparetic gait, define a detrimental combination termed diminished physiological fitness reserve that can greatly limit that can greatly limit performance of activities of daily living. The physiological features that underlie worsening metabolic fitness in the chronic phase of stroke include gross muscular atrophy, altered muscle molecular phenotype, increased intramuscular area fat, elevated tissue inflammatory markers, and diminished peripheral blood flow dynamics. Epidemiological evidence further suggests that the reduced cardiovascular fitness and secondary biological changes in muscle may propagate components of the metabolic syndrome, conferring added morbidity and mortality risk. This article reviews some of the consequences of poor fitness in chronic stroke and the potential biological underpinnings that support a rationale for more aggressive approaches to exercise therapy in this population.

The feasibility of cardiopulmonary exercise testing for prescribing exercise to people after stroke

BACKGROUND AND PURPOSE

Despite the importance of exercise training in mitigating cardiovascular risk, the development of exercise programs for people poststroke has been limited by lack of feasibility data concerning cardiopulmonary exercise testing (CPET) to inform the exercise prescription. Therefore, we examined the feasibility of CPETs for developing an exercise prescription in people ≥3 months poststroke.

METHODS

CPET results from 98 consecutively enrolled patients poststroke with motor impairments and 98 age- and sex-matched patients with coronary artery disease were examined at baseline and after 6 months of exercise training.

RESULTS

The proportion of patients with stroke and coronary artery disease attaining an intensity sufficient for prescribing exercise at baseline was 68.4% versus 82.7%, respectively (P=0.02) and 84.7% versus 83.8% (P=0.9) at 6 months. Women were less likely than men poststroke to achieve a sufficient intensity at baseline (40% versus 80.9%, P<0.001) but not at 6 months (78.3% versus 87.1, P=0.3). A clinically relevant abnormality occurred in 11.2% of stroke and 12.2% of patients with coronary artery disease on baseline CPETs (P=0.8) and 10.6% of stroke and 5.9% of patients with coronary artery disease on the 6-month CPET (P=0.4). No serious cardiovascular events occurred during 349 CPETs.

CONCLUSIONS

Most patients after stroke achieved a level of exertion during the CPET sufficient to inform an exercise prescription. At least 1 of 10 patients poststroke developed a clinically relevant abnormality on baseline and postprogram CPETs with no serious cardiovascular events. These data support the feasibility and safety of CPETs for prescribing exercise poststroke. Strategies to improve use of baseline CPETs for women poststroke require further investigation.

Exercise stress testing in subacute stroke patients using a combined upper- and lower-limb ergometer

OBJECTIVE

To assess functional cardiopulmonary exercise tolerance in a subset of patients with residual neurologic deficits after stroke by exercise stress testing using the Power Trainer, a combined upper- and lower-limb ergometer.

DESIGN

Prospective, observational study using a convenience sample.

SETTING

Clinical locomotor laboratory in a tertiary rehabilitation hospital.

PARTICIPANTS

Thirty subjects undergoing rehabilitation an average of 7.3 weeks after stroke.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Percentage of age-predicted maximal heart rate (APMHR) achieved and rate-pressure product (RPP).

RESULTS

Thirty subjects completed stress tests. Twelve of the 30 subjects were taking beta-blocker medications. Mean maximum heart rate +/- standard deviation achieved was 119+/-21 beats/min, equal to 75%+/-11% of APMHR. Ten subjects achieved 85% of APMHR or greater. Those not taking a beta-blocker attained 80%+/-10% of APMHR. The percentage increase in RPP from rest to maximal exercise for the whole group was 117%+/-44%. Four subjects developed cardiopulmonary signs or symptoms. Exercise prescriptions were provided to patients using the Karvonen formula. Overall subject satisfaction with the Power Trainer was high.

CONCLUSION

The Power Trainer can be used safely to assess cardiopulmonary exercise tolerance in a select subset of patients with neurologic impairments secondary to stroke. This information can be extrapolated for proper exercise prescription and may contribute to the investigation of coronary artery disease in this high-risk population.

Low-velocity graded treadmill stress testing in hemiparetic stroke patients

BACKGROUND AND PURPOSE

Coronary artery disease is prevalent in stroke patients and is an important factor affecting rehabilitation and health outcomes. However, the presence of neurological deficits in gait and balance has discouraged systematic application of exercise testing and prescription in the stroke population. We evaluated a novel graded treadmill stress test in paretic stroke patients and tested floor walking as a predictor of adequate neurological function to perform the treadmill test.

METHODS

Patients (n = 31) with residual paretic gait deficits after ischemic stroke were evaluated with graded treadmill at gait velocities individualized to functional mobility observed during an initial zero-incline treadmill tolerance test.

RESULTS

Most patients (30/31) tolerated testing, achieving mean heart rates of 129 +/- 14 beats per minute (mean +/- SD), representing 84 +/- 10% of maximal age-predicted heart rate. Evidence for asymptomatic myocardial ischemia was found in 29% of those without known coronary artery disease. Exercise termination was more often due to generalized fatigue than cardiopulmonary intolerance (23/31 versus 4/31; P < .0001) or hemiparetic leg fatigue (1/31; P < .0001). Floor walking across a wide range of velocities (0.25 to 2.5 mph) demonstrated a strong linear relation with treadmill velocities (n = 24; r = 80; P < .0001); all patients floor walking at > or = 0.5 mph had adequate neuromotor function to perform the exercise test.

CONCLUSIONS

These findings suggest that graded treadmill exercise testing, with proper safety precautions, can be used to assess cardiopulmonary function in paretic stroke patients. A simple floor-walking test predicts adequate neurological function to perform the exercise test. Exercise capacity is most limited by generalized fatigue and not by the paretic limb, supporting a rationale for endurance training in this population.