Maximal or peak aerobic capacity (V˙O2peak) during a maximal-effort graded exercise test is considered by many to be the “gold standard” outcome for assessing the effect of exercise training on cardiorespiratory fitness. The reliability of this measure in Parkinson disease (PD) has not been established, where the degree of motor impairment can vary greatly and is influenced by medications. This study examined the reliability of V˙O2peak during a maximal-effort graded exercise test in subjects with PD.
Seventy healthy middle-aged and older subjects with PD Hoehn and Yahr stage 1.5–3 underwent a screening/acclimatization maximal-effort treadmill test followed by two additional maximal-effort treadmill tests with repeated measurements of V˙O2peak. A third V˙O2peak test was performed in a subset of 21 subjects.
The mean V˙O2peak measurement was 2.4% higher in the second test compared with the first test (21.42 ± 4.3 vs 21.93 ± 4.50 mL·kg−1·min−1, mean ± SD, P = 0.03). The intraclass correlation coefficients (ICC) for V˙O2peak expressed either as milliliters per kilogram per minute or as liters per minute were highly reliable, with ICC of 0.90 and 0.94, respectively. The maximum HR (ICC of 0.91) and final speed achieved during the tests (ICC of 0.94) were also highly reliable, with the respiratory quotient being the least reliable of the parameters measured (ICC of 0.65).
Our results demonstrate that measurement of V˙O2peak is reliable and repeatable in subjects with mild to moderate PD, thereby validating use of this parameter for assessing the effects of exercise interventions on cardiorespiratory fitness.
1Geriatrics Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, MD; 2Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD; 3Department of Neurology, University of Maryland School of Medicine, Baltimore, MD; 4Maryland Exercise and Robotics Center of Excellence, Veterans Affairs Rehabilitation Research & Development Service, Baltimore Veterans Affairs Medical Center, Baltimore, MD; and 5University of Maryland School of Nursing, Baltimore, MD
Address for correspondence: Leslie I. Katzel, M.D., Ph.D., Geriatrics Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, BT/18/GR, 10 N. Greene Street, Baltimore, MD 21201; E-mail: firstname.lastname@example.org.
Submitted for publication January 2011.
Accepted for publication April 2011.