Calf capacity measurements in healthy populations: A systematic review

Following PRISMA 2020 guidelines and registered in PROSPERO (CRD42025638986), the review included a comprehensive search of three databases, along with citation tracking and manual reference checks conducted in February 2025. Sixty-five peer-reviewed studies were included, encompassing a total of 3020 participants aged 18–65. The review focused on objective measures of plantar flexor capacity, such as force, torque, and repetition maximum, and considered studies that reported psychometric properties. Endurance was mostly assessed using heel raise tests. These showed high intra-session reliability (intraclass correlation coefficient (ICC) ranging from 0.77 to 0.97), but results varied significantly between individuals. Isometric and isokinetic tests also demonstrated good-to-excellent reliability (ICC 0.74–0.99), although the protocols used were highly variable across studies. Isotonic testing was the least frequently employed method. In conclusion, while isokinetic and isometric tests offer reliable assessments, their use is limited by accessibility and inconsistent protocols. The heel raise test remains a popular method for evaluating endurance but suffers from a lack of standardization. Isotonic testing is underutilized and presents an opportunity for further methodological development.