Physical Activity Patterns of Pediatric Heart Transplant Patients

Purpose An active lifestyle is crucial for co-morbidity prevention in pediatric cardiac transplant patients(CTxP). The purpose of this study was to evaluate daily physical activity in CTxP and to identify relationships between anthropometric measurements, cardiac function and physical activity habits.

Methods Anthropometric measures and resting 2D echocardiograms were obtained. CTxP wore an Actigraph GT1M accelerometer for 7 days and were ask to maintain normal activity. Data were considered valid if the patient had accelerometer counts for ≥5 days with ≥10 h of recording time/day. The thresholds for categorizing levels of physical activity for the accelerometer were <400 counts/minute for sedentary activity, 401-1900 counts/minute for light activity, 1901-3918 counts/minute for moderate activity and >3918 counts/minute for vigorous activity. Correlations were examined using SPSS18.

Results Fourteen CTxP were included(males N=7) and were 12.9±2.2 years old. Their BMI was 23.7±9.5kg/m2(61±30 percentile). CTxP attained 8078±2232 steps/ day. They attained 168.2±35.8 activity counts per minute which is low compared to range of 381.6-646.5 activity counts per minute(Troiano et al, 2007) reported in similar-age and gender controls. CTxP engaged in sedentary activity for 13.1±2.0 hours/day, light activity for 2.3±0.8 hours/day, moderate activity for 0.56±0.2 hours/ day and vigorous activity for 0.74±2.2 hours/day. Resting ejection fraction was normal for all patients(60±7%). Daily step count was negatively correlated with ejection fraction(-0.609; p=0.02). There was a positive relationship between ejection fraction and minutes of daily vigorous physical activity(0.82; p<0.01). There was a negative correlation between minutes of light physical activity and ejection fraction(-0.674; p=0.02).

Conclusions Our CTxP did not attain the recommended 12-15,000 steps/day for a healthy BMI in childhood. Interestingly, the patients did attain one hour of moderateto- vigorous physical activity each day, but were inactive for the remainder of the day. It is unclear if the amount of vigorous physical activity is a result of higher ejection fraction or is facilitated by it. The relationship between ejection fraction and quantities of physical activity encourage further investigation.