Table 2

Physical fitness tests

TestPurposeProcedure
Cooper test (CT)Aerobic power, indirect estimation of VO2maxThe test was performed as described by McArdle et al.17 Internal reliability analysis identified an intraclass correlation (ICC) of 0.93 for female and 0.94 for male athletes
Jump coordination test (JCT)Agility and quicknessThe athletes performed two-footed jumps throughout the course with the goal of completing 26 jumps as quickly as possible. The course was designed so that the athlete jumped forwards, backwards and sideways during the test with hurdles of varied heights (15–36 cm). The athlete was instructed to face forward with his/her hips and shoulders perpendicular to the forward direction. Internal studies identified an ICC of 0.89 for female and 0.91 for male young ski racers
Unilateral leg press strength test (ULST)Maximal isometric leg extension strength in a closed kinetic chainThe athletes performed three one-leg isometric leg extensions. The greater trochanter, lateral intercondylar notch and lateral malleolus were used as landmarks to ensure that a knee angle of 100° was reached (180°=fully extended knee). The calculated strength parameters were the mean absolute leg force (ABS ULST) and the mean relative leg force (REL ULST). The reliability for isometric testing is very high.18 An internal analysis identified an ICC of 0.95 (female) and 0.96 (male)
Counter movement jump (CMJ)Explosive leg powerJumps were performed on a Kistler platform. The subject started the movement standing erect and then quickly bent at the hip, knees and ankles before starting the upward motion of the jump. Both hands were held on the hip. The highest jump height was calculated by the impulse-momentum method.19 The test−retest reliability of the CMJ on a force plate is high,20 in young ski racers. Analyses identified an ICC of 0.96 and 0.97 for females and males, respectively
Drop jump (DJ)Reactive leg power from a 40 cm high podiumThe subjects were instructed to drop from the podium with a posture as upright as possible, and to jump as high as possible with minimal ground contact time. The subjects were allowed to use their arms to generate momentum when jumping. The reactive strength index (RSI) was calculated by dividing the jump height (mm) of the first jump by the ground contact time (ms).21 Reliability analysis identified an ICC of 0.97 for female and 0.92 for male athletes
Specific counter movement jump (SCMJ)Explosive leg powerThree trials were performed with ski-jumping boots (Rass, Schönheide, Germany) to restrict the ankle joint. The subject squatted down until a 110° knee angle was reached. The subject was allowed to eccentrically preload further, but was not allowed to raise the body before the preload. Hands were kept clasped behind the back. The test−retest reliability of SCMJ was similar to that of the CMJ; namely, ICCs of 0.95 and 0.96 were identified for females and males, respectively
Core strength test (CST)Maximal isometric core strengthThe self-developed test device comprises a tension belt connected to a force transducer. To measure trunk flexion strength, the subjects lie in a supine position with their knees flexed at 90°, feet flat and pelvis fixated by a padded belt. The chest belt was set above the sternum level and the hip belt was placed below the anterior iliac spine. To measure trunk extension, the subjects laid in the prone position with the tension belt placed under the axillary fossa and the hip belt over the buttocks. Isometric contraction was held for 3 s. Subjects performed three trials, and the highest force was recorded. The measured parameters were the absolute flexion and extension forces (ABS FF, ABS EF, sum of both). Relative flexion and extension forces (REL FF, REL EF, sum of both) and ratio of the absolute flexion to extension force (FLE:EXT R) were calculated. Reliability analysis identified ICCs between 0.94 and 0.98
Strength endurance test (SET)Jump strength enduranceThis test was performed similarly to the test described by Brown and Wilkinson.22 The athletes jumped with both feet laterally onto a box (width 30 cm, length 100 cm), then to the other side, alternating back and forth for 90 s. The height of the box was adjusted to the apex of each athlete's patella. The number of jumps was recorded. Reliability analysis identified an ICC of 0.869 for female and 0.897 for male athletes
Line run test (LRT)Anaerobic enduranceThe athlete started at the first medicine ball, with one hand on the ball, and moved with side steps as quickly as possible to the second, third and fourth ball, finally touching the fourth ball until 32 contacts were completed. The line run test index (LRTI), that is, the running time divided by the number of ball contacts, was calculated. Reliability analysis identified an ICC of 0.92 for female and 0.92 for male athletes