Effects of detraining on cardiorespiratory fitness of individuals with chronic stroke.

BACKGROUND: Aerobic training can improve cardiorespiratory fitness in individuals after stroke. However, the effects of short-term and long-term detraining are not well known. OBJECTIVE: To determine the effects of short-term (1-month) and long-term (6-month) detraining on cardiorespiratory fitness (VO2peak) of individuals after stroke, who participated in aerobic training. METHODS: A cohort study was developed. Twenty adults (57 ± 11 years old) with stroke were included. After completing an outpatient aerobic training, participants were divided into gain group (VO2peak increase >1.3 ml.kg-1.min-1 from before to immediately after the training) or non-gain group (VO2peak change ≤1.3 ml.kg-1.min-1). Cardiorespiratory fitness (VO2peak), obtained by the cardiopulmonary exercise test was assessed one and 6 months after the end of the training (short- and long-term detraining, respectively), or collected retrospectively from patient chart (before and after the training). RESULTS: There was found a significant interaction effect (time*group) for VO2peak (F= 6.108;p < 0,001). Higher values in the VO2peak observed in the gain group with the aerobic training (F = 25.86; p< .001) were significantly reduced with short-term detraining, reaching values similar to that observed before the training and to that of the non-gain group (F = 14.81;p= .001). Both groups had similar VO2peak values within long-term detraining (F = 2.70;p= .12), with no significant differences from the values observed before the training and after short-term detraining (0.11 ≤ p≤ 1.00). CONCLUSIONS: Detraining on cardiorespiratory fitness of individuals after chronic stroke occurred within only 1 month. Therefore, it is important to maintain aerobic training throughout life.

Reliability and validity of the incremental shuttle walking test in individuals after stroke.

BACKGROUND: There are limitations to perform the cardiopulmonary exercise test (CPET) and the six-minute walking test (6MWT) in clinical settings. The incremental shuttle walking test (ISWT) might be an alternative assessment of exercise capacity and an estimation of cardiopulmonary fitness after stroke. OBJECTIVES: To investigate the test-retest and inter-rater reliabilities, the standard error of measurement (SEM) and the minimal detectable change (MDC) of the ISWT, its construct validity to assess exercise capacity and its concurrent validity to estimate cardiopulmonary fitness after stroke. METHODS: Prospective diagnostic accuracy study. Fifty-one individuals (54 ± 11 years) at the chronic phase (65 ± 73 months after stroke) were included. The distance walked, in meters, during the 12-stage-ISWT and the 6MWT and the peak oxygen uptake (VO2peak, ml.kg-1.min-1) in the CPET (gold standard) were assessed. RESULTS: Significant and high to very high magnitude test-retest and inter-rater reliabilities (0.88≤ICC≤0.93) of the ISWT was found. The SEM for both reliabilities was small (-23.35 m≤ SEM≤41.47 m). The MDC for test-retest and inter-rater reliabilities were 114.63 m and 64.53 m, respectively. For construct validity, a significant and high magnitude correlation between the ISWT and the 6MWT was found (ICC = 0.82). For the concurrent validity, a significant, but low magnitude correlation was found between the ISWT and the VO2peak (rho = 0.42). CONCLUSIONS: The ISWT demonstrated adequate reliabilities and construct validity for exercise capacity assessment. However, the concurrent validity of the ISWT as an estimation of cardiopulmonary fitness still requires further research.