## 2 Materials and Methods
### Study Design and Procedures  
Surface electromyography (EMG) was used to investigate the electrical activity of selected muscles in three different classical ballet tasks: (1) standing in parallel position; (2) demi-pointe releve in the parallel position; and (3) demi plie in first classical ballet position. Each task was conducted in the classical technique (no imagery) and with dance imagery according to the Franklin Method(r) [7]. The rationale for choosing these ballet tasks for analysis was as follows: parallel position, demi pointe releve, demi plie in first classical ballet position are dance elements of gradually increasing difficulty used by the study subject in everyday training in the ballet school. The mental images described below were chosen according to the Franklin Method(r). [PERSON] described these mental images as specific for the positions examined in our study [7]. The study subject performed three tasks barefoot with and without dance imagery, each repeated three times:1. Standing in a parallel position for 10 s. A parallel position involved an upright standing position with the feet located parallel and medial borders of the feet adhered to each other (Figure 1). The task was carried out in classical technique (no imagery) and with mental imagery called foot dome, according to the Franklin Method(r) [7] (p. 247). In this imagery, the study subject visualized a waterspour spraying upward from between the ankles [7] (p. 247).
2. Demi pointe releve in the parallel position (Figure 1). The task was divided into three phases: (1) lifting the heel from parallel position into demi pointe releve (3); (2) standing in demi pointe releve (5 s); (3) lowering the heel from demi pointe releve into parallel position (3 s). The task was conducted in classical technique (no imagery) and with mental imagery called the wheelbarrow, according to the Franklin Method(r) [7] (p. 115). In this imagery, the study subject visualized that: (1) his foot turned into a wheelbarrow as he lifted his heel off the ground; (2) the toes push against the floor as the weight of the body is lifted upward [7] (p. 115).
3. Demi ple in first classical ballet position (Figure 2). The task was divided into two phases: (1) bending the knees from first position into demi ple (4 s), and (2) straightening the knees from the demi ple into first position (4 s). The task was carried out in the classical technique (no imagery) and with two mental imageries called (1) the kneecap float, and (2) space behind the kneecap [7] (p. 119). In this imagery, the study subject respectively visualized: (1) the kneecap floating perpendicularly away from the femur as he extended the knee; and (2) the space behind the kneecap increasing, creating a little cushion of space for the kneecap to glide on [7] (p. 119).  
Figure 1: Bilateral placement of the electrodes on the tested muscles: lumbar erector spinae, rectus abdominis, vastus medialis, long head of biceps femoris, lateral head of gastrocnemius, tibialis anterior, and fibularis longus with the ground electrode placed over the right posterior superior iliac spine. The first and last pictures present the parallel position. The second to fourth pictures present standing in demi pointe releve.