Kichline T, et al. - Researchers examined 71 youth (M=13.34 y) with chronic abdominal pain in order to better understand their physical activity levels. In addition, they investigated whether day-level physical activity is related to next day pain intensity in order to identify any intraindividual heterogeneity. Youth with chronic abdominal pain did not report meeting recommended levels of moderate-to-vigorous physical activity per day. Further, a random effect of the previous day’s moderate-to-vigorous physical activity in predicting pain severity was noted. Within-person total sleep time was noted to have a small significant negative effect as a predictor of pain severity. These findings emphasize the significance of separating between-person and within-person differences when the relationship between physical activity and pain severity is examined.