Elaboration of an External Rotators Fatigue Test With an XCo

At first, the reliability of the Xco endurance test will be assessed in sedentary adults. Then, the reliability of the test will be assessed in overhead athletes. The experimentation will include two sessions. During those sessions, the impact of fatigue (induced by the test) on rotator cuff muscles strength and on functional test performance (Single Arm Medicine Ball Throw) will be assessed. A time of 7 to 10 days will be provided between the two sessions.

To perform the XCo endurance test, the participant will be seated on a chair, arm at 90° of abduction (in frontal plane), elbow flexed at 90 degrees and positioned on a wooden support. From a 90 degrees of abduction and a neutral position of rotation, the participants will be asked to realise an external rotation movement of 90 degrees and then to go back to the starting position as many times as possible at a speed of 140 bpm. Mechanical stops (the wall and an adjustable height table) will be added to make sure that the participants respected the entire range of motion. After adjusting the position, it will be asked to the participants to perform 2 repetitions of 5 movements at 140 bpm (in eccentric and concentric) to get familiar to the rhythm. Thirty seconds of rest will be provided between the 2 repetitions to avoid the appearance of fatigue before the test.

Then, the participants will begin the test. The objective of the test will be to perform the movement as long as possible. The test will be stopped if the volunteers is not able to maintain the rhythm or to do the movement anymore. The Modified Borg Scale will be used to be sure that each subject was really exhausted when the test was stopped. For that purpose, each of them will have to quantify their level of exhaustion on the scale (maximum score = 10) every 30 seconds.