Test–Retest of a Novel Wii Board–Based Device to Assess Eccentric Knee Flexor Strength During the Nordic Hamstring Exercise

Abstract

This study aimed to assess the test–retest reliability of a Wii board–based device to assess the eccentric knee strength. Healthy participants (n = 20, 22.7 [3.4] y, 1.71 [0.09] m, 69 [13] kg) performed 2 assessments—days 1 and 2—of the Nordic hamstring exercise (3 trials per day, 3 min of rest between trials, and 48 h between trials) on a padded board with an attached Wii Balance Board (WBB). A ratchet inelastic strap made the contact between the participant’s distal aspect of both legs and the inverted upper surface of the WBB. The means among 3 trials were used to extract the absolute strength and the left and the right limb strengths. No between-session differences were found (P range = .691–.981). The intraclass correlation coefficient range showed excellent results (.905–.926), as the Cronbach α test (above .94). The correlation was high (r > .91; .820 < r2 < .862). The Bland–Altman analysis returned high levels of agreement. The standard error of measurement ranged from 5.56 to 11.07 N and the minimal detectable change from 15.42 to 30.68 N. The percentage of standard error of measurement values were 2.95%, 3.74%, 2.88%, respectively, for absolute strength, right limb strength, and left limb strength. The adapted system showed an excellent cost–benefit relationship with optimal test–retest reliability. The findings suggest that the adapted system, using the WBB, is a reliable method for measuring the eccentric knee strength.

Does an Adjusted Kinematic Model Predict the Relative Eccentric Force During Nordic Curl?

“…Previous studies showed the WBB validity and reliability compared with a force platform, and the reliability of the Nordic exercise system using the WBB. 9,16 After an initial familiarization session and following a warm-up set of submaximal bilateral NHE (using an anchored elastic band to assist the exercise), the participants were asked to perform 3 trials of maximal NHE (actual NHE without any assistance with controlled velocity of execution using a digital metronome; 3 min of rest between trials was allowed). Each subject was asked to refrain from strenuous exercise or training 48 hours before assessments, and to avoid eating 2 hours before testing.…”

“…7 Other kinetic measurements using the Nordic curl are available using commercial or customized systems. 8,9 However, their lack of portability and the elevated cost (approximately $5000) may limit the use of their assessment for many coaches.…”