Over time, decreased levels of PA are generally associated with impairments of vascular function and structure and increased cardiovascular risk. This becomes particularly important when PA levels are limited in children and adolescents with a physical disability, such as cerebral palsy. Thus, early vascular assessments in this at-risk population may assist in determining potential CV risk factors. In this study we purposefully studied vascular health in the most functional adolescents with CP to contrast their PA levels and vascular health with their healthy peers. The primary findings did not confirm our hypothesis that arterial function and structure in adolescents with CP (GMFCS level I-II) are different from a healthy control group despite individuals with CP spending significantly less time performing vigorous PA in comparison to their typically developing peers.
In this study, the primary risk factor (for future cardiovascular health) of interest was level of PA, as measured using the Exercise Questionnaire [38
]. Both groups spent similar amounts of time performing light-to-moderate PA; however, the CP group spent a significantly less amount of time engaging in vigorous intensity PA. Despite this discrepancy in time spent in high intensity PA, no group differences were seen in any of the measured indices of vascular health. It has been suggested that the strongest relationships between exercise interventions (comparable to levels of PA) and enhanced endothelial function exist in groups with relatively impaired FMD a priori. The tightest correlations between PA and FMD response have been shown to exist in the lowest tertiles of endothelial function [40
]. Considering this, there is no reason to believe that the control group has experienced vascular dysfunction, which would predispose them to a positive vascular adaptation as a result of their higher levels of vigorous activity in comparison to the seemingly healthy CP group.
No significant differences between groups were found in cPWV or pPWV. These values were comparable to a previous study assessing PWV in a slightly younger group of healthy children (10.1 ± 0.3
yrs) who showed very similar cPWV values (4.2 ± 0.4
] to those in both groups in the current study (). This indicates preserved arterial stiffness at this time point for both the control and CP group. Similarities in PWV between groups in this study may be reflective of similar levels of low intensity PA, as indicated by the same amount of time spent in light and moderate intensity PA as well as the same total time spent performing PA per week ().
No differences were found between groups in either carotid distensibility or c
IMT. Throughout the lifespan, habitual PA has been shown to positively influence arterial distensibility [14
]. Age-related decreases in arterial distensibility and increases in stiffness have been reported [18
]; however, increased levels of PA have been suggested to delay the age-dependent loss of arterial distensibility, in proportion to the amount and/or intensity of exercise [18
]. Although there was no difference in distensibility between the CP and control group at this time, sufficient rationale is provided for this clinical group of adolescents to increase their levels of high intensity PA at an early stage and maintain these behaviours into adulthood in an attempt to mitigate these normative age-related changes.
IMT measurements were also similar between groups and were comparable to other control groups used in previous studies [43
]. Iannuzzi and colleagues (2004) [43
] characterized the differences in c
IMT between obese children and age-matched control subjects (6–14 years) and showed a significantly greater IMT in the obese group in comparison to the healthy controls (0.55 ± 0.08
mm versus 0.49 ± 0.09
mm). The c
IMT of the obese children in the aforementioned study was approximately 24% and 25% greater than the c
IMT of the present study's CP and control group, suggesting healthy vascular structure in both groups in the current study.
In a previous study assessing the relationship between habitual PA (as measured using the double labeled water approach) and brachial FMD in 5–10-year-old children, a significant correlation was found (r
= 0.39, P
= 0.007), highlighting PA as the most influential variable in predicting the FMD response [9
]. This group reported that physical fitness, as assessed using an incremental discontinuous treadmill-based exercise test, and levels of PA, as measured using Actigraph accelerometers, were lowest in the lowest %FMD and %FMD/SRAUC
tertile. These relationships between fitness, PA, and FMD response were significant, and it was concluded that PA measurements were the best predictors of endothelial (dys) function in this young group [40
]. These data support the concept that PA exerts its protective effect on CV health via the endothelium and draws attention to the role of lifestyle modifications, specifically increases in levels of habitual PA in pediatric practice.
This cross-sectional study is the first to characterize indices of vascular health in higher functioning youth with CP and to make comparisons to a group of their typically developing peers. Children harbouring classic CV risk factors, including physical inactivity have been shown to exhibit impairments in vascular function and structure early in life and have an increased risk of premature atherosclerosis in adulthood [44
]. It has been shown that levels of both PA and inactivity track significantly from adolescence (9 to 18
yrs) to young adulthood placing inactive children at an increased risk of becoming physically sedentary adults [45
]. With evidence of physical inactivity being a significant precursor to CVD-related death and moderate levels of fitness providing protective effects against the influence of traditional risk factors on mortality [46
], the value of well-established, healthy patterns of habitual PA in pediatric practice must not be overlooked. In a group of youth that may have increased susceptibility to physical inactivity, identifying any early alterations in vascular function and structure may assist in identifying preclinical vascular disease, allowing for intervention at the earliest stage possible.