Undergoing 8 weeks of moderate-intensity endurance training can improve muscular microvasculature in patients with sickle cell disease (SCD) according to results from a clinical trial (ClinicalTrials.gov Identifier: NCT02571088) published in Blood.

Two major clinical manifestations of SCD are hemolytic anemia and iterative vaso-occlusive crises. Additionally, the muscular microvascular remodeling that accompanies SCD is profound, so researchers aimed to assess whether undergoing endurance training improved the microvasculature in skeletal muscle of patients with SCD.

Related Articles

“Considering the feasibility and the safety of endurance exercise training in patients with SCD and the potential benefits for patients of such an intervention, it is important to consider endurance exercise training as a possible strategy to counteract or even reverse, at least in part, the skeletal muscle microvascular defects observed in adult patients with SCD,” explained the researchers.

Continue Reading

Researchers biopsied the vastus lateralis muscle of 40 patients randomly assigned to undergo endurance training (15 patients) or no training (17 patients), with complete data available for 32 total patients. All patients performed a submaximal incremental exercise prior to and following the period of endurance training.

No significant differences in anthropometric, hemoglobinic, or hematologic characteristics between the 2 groups were present at baseline. Baseline muscle microvascular features were similar between patients who did and did not undergo training as well as between patients receiving hydroxyurea and patients not receiving hydroxyurea.

Patients who underwent training participated in 40-minute sessions on a cycle ergometer 3 times a week for 8 weeks. Researchers used histological analysis to compare the microvascular benefits in patients with SCD undergoing training compared with patients not undergoing training, and found increased capillary density (P =.003), functional exchange surface (P <.0001), and number of capillaries around a fiber (P =.015) in the training group. There was a 23% change in number of capillaries around a fiber in type I muscle fibers in patients who underwent training (P =.0004).

No significant difference in the morphology of capillaries occurred between the groups. Measurements of physical ability, such as oxygen consumption, improved in the training cohort compared with the nontraining cohort.

Taken together, these results indicate a partial reversal of the microvascular defects that affect skeletal muscles in patients with SCD.

“The present study suggests that training-induced rearrangement of the microvascular network due to capillary growth may contribute to the concomitant improvement in the patients’ physical capacity,” the researchers concluded.


  1. Merlet AN, Messonnier LA, Coudy-Gandilhon C, et al. Beneficial effects of endurance exercise training on skeletal muscle microvasculature in sickle cell disease patients [published online November 19, 2019]. Blood. doi:10.1182/blood.2019001055