Exercise intolerance in individuals with postconcussion syndrome.

CONTEXT Little is known about exercise intolerance or the utility of an exercise evaluation in patients with postconcussion syndrome (PCS). OBJECTIVE To assess exercise intolerance in male and female patients with PCS. DESIGN Cross-sectional study. SETTING Laboratory setting. PATIENTS OR OTHER PARTICIPANTS Participants included a convenience sample of 34 patients with PCS (17 males, 17 females; age = 25.9 ± 10.9 years) and 22 uninjured individuals on whom we gathered historical deidentified laboratory data (control group; 11 males, 11 females; age = 23.3 ± 6.2 years). MAIN OUTCOME MEASURE(S) Self-reported symptoms, heart rate, systolic and diastolic blood pressures (BPs), and the Borg rating of perceived exertion were measured before, during each minute of, and immediately after a graded treadmill exercise test (Balke protocol). Exercise was stopped when participants could no longer maintain the effort or reported the onset of or increase in PCS symptoms. RESULTS Exercise test duration (8.5 ± 4.4 minutes versus 17.9 ± 3.6 minutes; t51 = 1.8, P < .001), heart rate (142.8 ± 24.1 versus 175.2 ± 17.4; t54 = -5.5, P < .001), and systolic BP (142.1 ± 18.3 mm Hg versus 155.5 ± 24.5 mm Hg; t53 = 2.3, P = .02) were lower, and diastolic BP (78.4 ± 10.2 mm Hg versus 73.5 ± 11.7 mm Hg; t53 = 2.2, P = .03) was higher at test cessation in the PCS than control group. Cox regression showed the odds of a shorter exercise duration were nearly 8 times greater in the PCS than control group (hazard ratio = 7.93; 95% confidence interval = 3.39, 18.56). In the general linear models that adjusted for differences in test duration, rating of perceived exertion was the only physiologic measure to show an overall difference between groups, with the control group reporting higher ratings than the PCS group (t53 = -6.0, P < .001). Within the PCS group, systolic BP was the only measure to show a sex effect, with males showing higher pressure readings than females throughout the exercise tests (t31 = 2.8, P = .009). CONCLUSIONS Patients with PCS had a symptom-limited response to exercise, and the treadmill test was a potentially useful tool to monitor the recovery from PCS.