Adults born preterm have lower peripheral skeletal muscle area and strength.

Prematurity is associated with lower exercise capacity, which relies on the integrity of the cardiovascular, pulmonary, and skeletal muscle systems. Our animal model mimicking prematurity-associated conditions showed altered muscle composition and atrophy in adulthood. This study aimed to compare muscle composition and strength in adults born preterm versus full-term controls. This observational cohort study recruited 55 adults born preterm, ≤ 29 weeks' of gestation and 53 full-term controls who underwent musculoskeletal ultrasound imaging to assess morphology of the rectus femoris at rest and during a maximal voluntary contraction. Maximal voluntary contraction of the hands and legs were measured by manual dynamometry. In adults born preterm, there was lower muscle strength (handgrip: - 4.8 kg, 95% CI - 9.1, - 0.6; knee extensor: - 44.6 N/m, 95% CI - 63.4, - 25.8) and smaller muscle area (- 130 mm2, 95% CI - 207, - 53), which was more pronounced with a history of bronchopulmonary dysplasia. Muscle stiffness was increased in the preterm versus term group (0.4 m/s, 95% CI 0.04, 0.7). Prematurity is associated with alterations in skeletal muscle composition, area, and function in adulthood. These findings highlight the necessity to implement preventive and/or curative approaches to improve muscle development and function following preterm birth to enhance overall health in this population.