Effects of the Functional Heel Drop Exercise on the Muscle Architecture of the Gastrocnemius.

Abstract

The architectural characteristics of a muscle determine its function. To determine the architectural adaptations of the lateral gastrocnemius (LG) and medial gastrocnemius (MG) muscles after a functional eccentric strength training protocol consisting of heel drop exercises, followed by a subsequent detraining period. Pretest and posttest. Training rooms and laboratory. The participants (N = 45) who were randomly divided into an experimental group (EG, n = 25) and a control group (CG, n = 20). The 13-week intervention included participants (N = 45) who were randomly divided into an EG (n = 25) and a CG (n = 20). The EG performed a week of control and training, 8 weeks of eccentric training, and 4 weeks of detraining. The CG did not perform any type of muscular training. The architectural characteristics of the LG and MG muscles were evaluated at rest in both groups using 2-D ultrasound before (pretest-week 1) and after (posttest-week 9) the training, and at the end of the detraining period (retest-week 13). One-way repeated measures analysis of variance was used to determine training-induced changes in each of the variables of the muscle architecture. After the training period, the members of the EG experienced a significant increase in the fascicle length of LG (t = -9.85, d = 2.78, P < .001) and MG (t = -8.98, d = 2.54, P < .001), muscle thickness (t = -6.71, d = 2.86, P < .001) and (t = -7.85, d = 2.22, P < .001), and the pennation angle (t = -10.21, d = 1.88, P < .05) and (t = -1.87, d = 0.53, P < .05), respectively. After the detraining period, fascicle length, muscle thickness, and pennation angle showed a significant decrease. In the CG, no significant changes were observed in any of the variables. The heel drop exercise seems to generate adaptations in the architectural conditions of LG and MG, which are also reversible after a detraining period. These results may have practical implications for injury prevention and rehabilitation programs.