The Sit Up Squat Stand test and Hand Grip Strength: What is the role of tests of muscle power in risk assessment in Anorexia Nervosa?

Abstract

Objectives: To investigate the validity and reliability of two variants of the Sit Up Squat Stand Test (SUSS) and Hand Grip Strength (HGS) in predicting BMI and BMI risk level in hospitalised patients with Anorexia Nervosa (AN). Methods: 25 inpatients with AN were tested roughly weekly for up to 16 weeks. Muscle power was assessed by two independent researchers. Results: Intra-class coefficients (ICCs) indicated high Inter-Rater Reliability (IRR) for the HGS (10 participants). Cohen's Kappa showed moderate IRR for the SUSS test (25 participants). Stepwise multiple regression showed that the SUSS tests plus HGS predicted BMI and BMI risk level explaining about two-third of the variance. Each test individually had lower predictive value. There was a little difference between the two versions of the SUSS tested. Conclusions: HGS and SUSS are valid and reliable measurements of muscle power in AN. Together, the SUSS tests and the HGS represent a useful and effective measure of muscle power and hence one aspect of physical risk in Anorexia Nervosa. In the light of Covid restrictions, the SUSS test is one way that physical state can be monitored on video link in a way that is hard to falsify.