LAUSR

Cardiovascular fitness (CRF), measured by maximal cardiopulmonary exercise test and expressed as peak oxygen uptake (VO 2peak ), can well reflect the integrated function of whole-body physiological responses of involved cardiovascular, metabolic, musculoskeletal, and neuropsychiatric systems under exercise stress. Studies have firmly established the inverse association between CRF and cardiovascular disease (CVD) and all-cause mortality. Recent studies demonstrate that CRF is a stronger independent predictor for health outcomes than traditional risk factors. Improvement of CRF, irrespective of traditional risk factors and initial CRF level, produces substantial health benefits. Emerging studies have also supported CRF as a strong predictor for stroke incidence. These studies have observed a graded and inverse association between CRF and all types of stroke risk in the young and old, men and women, healthy and unhealthy population. Review, observational, and trail studies suggest that high CRF contributes to walking capacity and functional recovery in subacute and chronic phases of stroke. Despite these health benefits, low CRF is prevalent in stroke population. Reviews have reported an average VO 2peak of 14.6 mL/ kg per minute, and VO 2peak level in stroke survivor is about 53% of the ageand sex-matched health controls. Muscle atrophy, increased muscle fat mass, impaired cardiac function, and respiratory function, reduced peripheral blood flow, as well as diminished muscle strength, and impaired gait performance all contribute to the decline of CRF after stroke. Exercise training (ET) particularly aerobic training (AT) has been well established for improving CRF in stroke population. Cochrane review has shown that AT can elicit an increase of VO 2peak of 2.86 mL/kg per minute (95% CI, 1.76–3.96; P=0.00001). Actually, regular physical activity (PA) can substantially reduce stroke risk in a dose-response fashion. A 7.5-year follow-up in 487 334 participants displayed that every 4 metabolic equivalents (METs)-h/d (1 MET = a whole-body oxygen consumption of 3.5 mL O 2 /kg/min) increase in PA was associated with 5% and 6% decrease in ischemic stroke and intracerebral hemorrhage respectively. Study in 336 326 Koreans with an even age distribution showed that 1 to 2 times per week moderateto vigorous-intensity PA was associated with 16% lower stroke incident. Strategies to promote PA and ET in stroke population are critical. We provide a narrative review to address the association of CRF with stroke, examine the level and evolution of CRF poststroke, aiming to propose that improving CRF is essential in stroke rehabilitation, particularly in acute and early subacute phase, and assessing CRF level and prescribing ET in clinical practice should be considered as a strategy to promote PA and ET in stroke population. We assume that there is a substantial decline of CRF after stroke, particularly in subacute phase.