The six-minute walk test predicts cardiorespiratory fitness in individuals with aneurysmal subarachnoid hemorrhage.

BACKGROUND: Peak oxygen uptake (VO2peak) established during progressive cardiopulmonary exercise testing (CPET) is the "gold-standard" for cardiorespiratory fitness. However, CPET measurements may be limited in patients with aneurysmal subarachnoid hemorrhage (a-SAH) by disease-related complaints, such as cardiovascular health-risks or anxiety. Furthermore, CPET with gas-exchange analyses require specialized knowledge and infrastructure with limited availability in most rehabilitation facilities. OBJECTIVES: To determine whether an easy-to-administer six-minute walk test (6MWT) is a valid clinical alternative to progressive CPET in order to predict VO2peak in individuals with a-SAH. METHODS: Twenty-seven patients performed the 6MWT and CPET with gas-exchange analyses on a cycle ergometer. Univariate and multivariate regression models were made to investigate the predictability of VO2peak from the six-minute walk distance (6MWD). RESULTS: Univariate regression showed that the 6MWD was strongly related to VO2peak (r = 0.75, p < 0.001), with an explained variance of 56% and a prediction error of 4.12 ml/kg/min, representing 18% of mean VO2peak. Adding age and sex to an extended multivariate regression model improved this relationship (r = 0.82, p < 0.001), with an explained variance of 67% and a prediction error of 3.67 ml/kg/min corresponding to 16% of mean VO2peak. CONCLUSIONS: The 6MWT is an easy-to-administer submaximal exercise test that can be selected to estimate cardiorespiratory fitness at an aggregated level, in groups of patients with a-SAH, which may help to evaluate interventions in a clinical or research setting. However, the relatively large prediction error does not allow for an accurate prediction in individual patients.

Impaired muscle strength may contribute to fatigue in patients with aneurysmal subarachnoid hemorrhage.

Patients with aneurysmal subarachnoid hemorrhage (a-SAH) show long-term fatigue and face difficulties in resuming daily physical activities. Impaired muscle strength, especially of the lower extremity, impacts the performance of daily activities and may trigger the onset of fatigue complaints. The present study evaluated knee muscle strength and fatigue in patients with a-SAH. This study included 33 patients, 6 months after a-SAH, and 33 sex-matched and age-matched healthy controls. Isokinetic muscle strength of the knee extensors and flexors was measured at 60 and 180°/s. Maximal voluntary muscle strength was defined as peak torque and measured in Newton-meter. Fatigue was examined using the Fatigue Severity Scale. In patients with a-SAH, the maximal knee extension was 22% (60°/s) and 25% (180°/s) lower and maximal knee flexion was 33% (60°/s) and 36% (180°/s) lower compared with that of matched controls (P≤0.001). The Fatigue Severity Scale score was related to maximal knee extension (60°/s: r=-0.426, P=0.015; 180°/s: r=-0.376, P=0.034) and flexion (60°/s: r=-0.482, P=0.005; 180°/s: r=-0.344, P=0.083). The knee muscle strength was 28-47% lower in fatigued (n=13) and 11-32% lower in nonfatigued (n=20) patients; deficits were larger in fatigued patients (P<0.05), particularly when the muscle strength (peak torque) was measured at 60°/s. The present results indicate that patients with a-SAH have considerably impaired knee muscle strength, which is related to more severe fatigue. The present findings are exploratory, but showed that knee muscle strength may play a role in the severity of fatigue complaints, or vice versa. Interventions targeting fatigue after a-SAH seem necessary and may consider strengthening exercise training in order to treat a debilitating condition.

Impaired cardiorespiratory fitness after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: To assess cardiorespiratory fitness in patients following an aneurysmal subarachnoid haemorrhage and to explore this in fatigued and non-fatigued patients. DESIGN: Cross-sectional case-control study. SUBJECTS/PATIENTS: A total of 28 patients, 6 months post aneurysmal subarachnoid haemorrhage, and 28 sex- and age-matched controls. METHODS: Cardiorespiratory responses to a progressive cardiopulmonary exercise test on a cycle ergometer were obtained using indirect calorimetry. Fatigue was assessed using the Fatigue Severity Scale. RESULTS: Mean peak oxygen uptake (V̇O2peak) was significantly lower in patients (22.0 (standard deviation (SD) 6.2) ml/kg/min) than in controls (69% of controls, p < 0.001). All other cardiorespiratory fitness parameters were also lower, with peak levels ranging from 62% to 77% of matched controls. Mean V̇O2peak was 19.4 (SD 4.1) ml/kg/min in fatigued patients (63% of matched controls, p < 0.001) and 23.9 (SD 6.9) ml/kg/min in non-fatigued patients (74% of matched controls, p = 0.002). CONCLUSION: Cardiorespiratory fitness is impaired after aneurysmal subarachnoid haemorrhage, both in fatigued and non-fatigued patients. This finding may have implications for treatment.