Reliability and Construct Validity of the 6-Minute Racerunner Test in Children and Youth with Cerebral Palsy, GMFCS Levels III and IV.
OBJECTIVE
To determine the test-retest reliability and construct validity of a novel 6-Minute Racerunner Test (6MRT) in children and youth with cerebral palsy (CP) classified as Gross Motor Function Classification System (GMFCS) levels III and IV. The racerunner is a step-propelled tricycle.


METHODS
The participants were 38 children and youth with CP (mean age 11 y 2 m, SD 3 y 7 m; GMFCS III, n = 19; IV, n = 19). Racerunner capability was determined as the distance covered during the 6MRT on three occasions. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and smallest detectable differences (SDD) were calculated to assess test-retest reliability.


RESULTS
The ICC for tests 2 and 3 were 0.89 (SDD 37%; 147 m) for children in level III and 0.91 for children in level IV (SDD 52%; 118 m). When the average of two separate test occasions was used, the SDDs were reduced to 26% (104 m; level III) and 37% (118 m; level IV). For tests 1 to 3, the mean distance covered increased from 345 m (SD 148 m) to 413 m (SD 137 m) for children in level III, and from 193 m (SD 100 m) to 239 m (SD 148 m) for children in level IV.


CONCLUSIONS
Results suggest high test-retest reliability. However, large SDDs indicate that a single 6MRT measurement is only useful for individual evaluation when large improvements are expected, or when taking the average of two tests. The 6MRT discriminated the distance covered between children and youth in levels III and IV, supporting construct validity.
a Department of Rehabilitation Medicine , VU University Medical Center , Amsterdam , The Netherlands.
Eline A M
EA
Bolster
a Department of Rehabilitation Medicine , VU University Medical Center , Amsterdam , The Netherlands.
Annet J
AJ
Dallmeijer
b Department of Clinical Methods and Public Health , Academic Medical Centre Amsterdam , Amsterdam , The Netherlands.
G Sander
GS
de Wolf
c Department of Pediatric Rehabilitation, Section Physical Therapy , De Vogellanden Centre for Rehabilitation , Zwolle , The Netherlands.
Marieke
M
Versteegt
a Department of Rehabilitation Medicine , VU University Medical Center , Amsterdam , The Netherlands.
Petra E M van
PE
Schie
D000293:Adolescent; D002547:Cerebral Palsy / Q000145:classification / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D000070857:Walk Test / Q000295:instrumentation*; D016138:Walking / Q000502:physiology*; D055815:Young Adult
Cerebral palsy; GMFCS level III; GMFCS level IV; construct validity; exercise; fitness; racerunner; reliability