Increasing daily step counts improves physical fitness, reduces pain and arterial stiffness in sickle cell patients

Patients with sickle cell anemia (SCA) have long been discouraged from physical activity (PA). The aim of the present study was to assess the impact of increasing daily step counts on physical fitness, pain and vascular function in patients with SCA. Thirty-eight patients with SCA were recruited and equipped with a Fitbit wrist-worn accelerometer-based PA tracker for 5 weeks to objectively quantify their baseline daily step counts. Patients were then randomly assigned to one of the three groups: 1) control group: no specific information regarding PA was given for 8 weeks (N=12); 2) PA1 group: daily step counts increased by 25% of baseline for 8 weeks (N=12); 3) PA2 group: daily step counts increased by 25% for 4 weeks, then by 50% for 4 additional weeks (N = 14). Pain intensity and frequency decreased after the intervention in the PA1 and PA2 groups. In addition, patients from these two groups increased the distance walked in 6 minutes. Arterial stiffness decreased in both PA1 and PA2 groups, without any change in the autonomic nervous system activity. Several inflammatory markers slightly decreased in the PA2 group. Incubation of cultured endothelial cells with patient plasma showed a decrease in the percentage of ICAM-1 positive cells in the PA2 group. This study is the first to show that increasing daily PA by a simple way (i.e., increasing daily step count of 25-50%) for 8 weeks is sufficient to decrease pain, and improve physical condition and vascular function of patients with SCA.