Ankle Position-Dependent Muscle Swelling During Seated Leg Curl: Ultrasonographic Insights Into the Hamstrings and Medial and Lateral Gastrocnemius

Abstract Lisboa, F, Gomes, F, Kunevalik, G, Manske, I, Santos, V, Prado, A, Cavalcanti, A, Tricoli, I, Costa, B, Kassiano, W, Stavinski, N, Francsuel, J, and Cyrino, ES. Ankle position-dependent muscle swelling during seated leg curl: ultrasonographic insights into the hamstrings and medial and lateral gastrocnemius. J Strength Cond Res XX(X): 000–000, 2026—The seated leg curl is one of the most prescribed exercises in hamstring strength training. Although it is a monoarticular exercise, changing the position of the ankle may influence the engagement of the muscles involved during the exercise (i.e., hamstrings and gastrocnemius muscles). We compared the lateral gastrocnemius (LG), medial gastrocnemius, and hamstrings (HT) during the seated leg curl exercise with the ankle in a neutral ankle position (NAP), plantar flexion position (PFP), and a control condition (CON), in which subjects did not perform any exercise and instead remained at rest for a duration equivalent to the exercise sessions. Each condition was performed on a different day, once per week. Muscle swelling was measured immediately after exercise and at the corresponding time point in the control condition. Seventeen young women (18–37 years) performed the experimental protocols and control condition in a crossover and counterbalanced design. In the experimental conditions, subjects performed a specific warm-up with 50% of the initial load for the exercise, completing 12 repetitions, followed by 3 sets to concentric failure, with a 2-minute interval between sets in the following conditions: NAP and PFP. The primary outcome showed that NAP resulted in greater swelling in LG compared with the CON (mean difference = 0.05 cm; 95% CI: 0.004–0.11; ES = 0.6) and with PFP (mean difference = 0.07 cm; 95% CI: 0.009–0.14; ES = 0.6). For HT, swelling was greater in NAP compared with CON (mean difference = 0.18 cm; 95% CI: 0.08–0.2; ES = 1.1) and in PFP compared with CON (mean difference = 0.14 cm; 95% CI: 0.02–0.2; ES = 0.9), but no significant difference was found between NAP and PFP (mean difference = 0.03 cm; 95% CI: −0.16 to 0.24; ES = 0.2). Our findings suggest that in the NAP condition, there is muscle swelling in both the LG and HT, whereas in the PFP condition, muscle swelling is observed only in the HT.