Randomized Controlled Trial of the Effects of a Trunk Stabilization Program on Trunk Control and Knee Loading

Abstract

Many athletic maneuvers involve coordination of movement between the lower and upper extremities, suggesting that better core muscle use may lead to improved athletic performance and reduced injury risk. To determine to what extent a training program with quasistatic trunk stabilization (TS) exercises would improve measures of core performance, leg strength, agility, and dynamic knee loading compared with a program incorporating only resistance training (RT). Thirty-seven male subjects were randomly assigned to either an RT-only or a resistance and TS training program, each lasting 6 wk. Core strength and endurance, trunk control, knee loading during unanticipated cutting, leg strength, and agility were collected pre- and posttraining. Between-group analyses showed that the TS group significantly improved only core endurance when compared with the RT group (side bridge, P = 0.050). Within-group analyses showed that the TS group improved lateral core strength (maximum pull, cable on nondominant side; 44.5 ± 61.3 N, P = 0.037). Both groups increased leg strength (deadlift 1 repetition maximum; TS: 55.1 ± 46.5 lb, P = 0.003; RT: 33.4 ± 17.5 lb, P < 0.001) and decreased sagittal plane trunk control (sudden force release test; cable in front; TS: 2.54° ± 3.68°, P = 0.045; RT: 3.47° ± 2.83°, P = 0.004), but only the RT group decreased lateral trunk control (sudden force release; cable on dominant side; 1.36° ± 1.65°, P = 0.029). The RT group improved standing broad jump (73.2 ± 108.4 mm, P = 0.049) but also showed increased knee abduction moment during unanticipated cutting (1.503-fold increase (percentage body weight × height), P = 0.012). Quasistatic TS exercises did not improve core strength, trunk control, or knee loading relative to RT potentially because of a lack of exercises, including unexpected perturbations and dynamic movement. Together, these results suggest the potential importance of targeted trunk control training to address these known anterior cruciate ligament injury risk factors.