Pedometer-assessed physical activity in children and young adults with CKD

Abstract

Background and objectives: Data on physical activity are limited in children with CKD. The objectives of this study were to measure the level and correlates of physical activity in children and young adults with CKD and to determine the association of physical activity with physical performance and physical functioning.

Design, setting, participants, & measurements: Physical activity was measured for 7 days using pedometers; physical performance was measured by the 6-minute walk distance (6MWD) and physical functioning with the PedsQL 4.0.

Results: Study participants were 44 patients 7-20 years of age who had CKD stage 1-4 (n=12), had ESRD and were undergoing dialysis (n=7), or had undergone kidney transplantation (n=25). Participants were very sedentary; they walked 6218 (interquartile range, 3637, 9829) steps per day, considerably less than recommended. Physical activity did not differ among participants in the CKD stage 1-4, ESRD, and transplant groups. Females were less active than males (P<0.01), and physical activity was 44% lower among young adults (18-20 years) than younger participants (P<0.05). Physical activity was associated positively with maternal education and hemoglobin concentration and inversely with body mass index. Respective 6MWD in males and females was 2 and approximately 4 SDs below expected. Low levels of physical activity were associated with poor physical performance and physical functioning, after adjustment for age, sex, and body mass index.

Conclusions: In most participants with CKD, physical activity was considerably below recommended levels. Future studies are needed to determine whether increasing physical activity can improve physical performance and physical functioning.

Figure 1.

Pedometer-determined physical activity. (A) In males and females with CKD (dark bars) compared with healthy children in the United States (National Health and Nutrition Examination Survey 2005–2006; light bars) (22). Dashed lines depict recommended target levels of daily activity (13). (B) In males (light bars) and females (dark bars) with CKD according to age. Dashed lines depict recommended target levels of daily activity (13). The boxes represent the 25th (bottom), 50th (middle), and 75th (upper) percentile for each group. The error bars represent the 5th and 95th percentiles, and the dots represent outliers.

Figure 2.

Physical performance (6-minute walk distance) in children and young adults with CKD according to age. Light bars represent males and dark bars represent females. SD scores for each participant were calculated using age- and sex-specific normative values (15). The boxes represent the 25th (bottom), 50th (middle), and 75th (upper) percentile for each group. The error bars represent the 5th and 95th percentiles, and the dots represent outliers.