The Development and Assessment of Core Strength Clinical Measures: Validity and Reliability of Medicine Ball Toss Tests

Core strengthening has become a significant focus in physical fitness, performance training, injury prevention, and rehabilitation. Core strength is theorized to optimize athletic performance, reduce risk of injury, and facilitate return from injury. Reliable and valid measures of core strength are necessary to track progress and determine effectiveness of human performance training. The purpose of this study was to determine the reliability and validity of three medicine ball toss tests. A total of 20 healthy physically active males and females (Age: 22.7±7.8 years, Height: 164.79±25.70 cm, Weight: 70.95±12.34 kg) participated. Testing occurred in two sessions separated by one to seven days. During session one, isokinetic testing was performed followed by medicine ball toss tests. Isokinetic strength testing included torso flexion, extension, and rotation, standardized according to manufacturer’s recommendations. Medicine ball toss tests were performed in four directions: forwards, backward, and rotational (right/left). Subjects performed five practice trials of each throw, followed by a five-minute rest period. Following the rest period, subjects performed five measured medicine ball toss tests. Subjects performed only the medicine ball toss tests in session two. Average peak torque was utilized for analysis of isokinetic strength. The average distance of the first three medicine ball toss tests in each direction was utilized for analysis. Pearson correlations were calculated to assess validity between medicine ball toss tests in session one and the corresponding isokinetic strength. Intraclass correlation coefficients were calculated to determine the reliability of the medicine ball toss tests between sessions. No significant Pearson correlations were observed between the forward, backward, and rotational medicine ball toss tests and corresponding measures of isokinetic strength (r=-0.047, p=0.845; r=-0.074, p=0.756; r=-0.051, p=0.832 (right); r=0.18, p=0.447 (left), respectively). Significant intraclass correlations were observed between session one and two medicine ball toss tests (ICC=0.835; ICC=0.835; ICC=0.870 (right); ICC=0.909 (left); p