Normative values for isometric quadriceps peak torque using fixed dynamometry in healthy young adults

Abstract

RATIONALE: Assessment of muscle strength is recommended to measure weakness and inform exercise prescription in adults undergoing pulmonary rehabilitation. There is a lack of normative data for lower extremity muscle strength using fixed dynamometry in the clinical setting in young adults. OBJECTIVES: Primary objectives were to determine (i) normative values for isometric quadriceps peak torque (QT) using fixed dynamometry and (ii) the relationship between isometric QT with demographics, body composition, habitual physical activity and one-repetition maximum (1-RM) for knee extension. A secondary objective was to develop a preliminary equation to predict 1-RM knee extension using isometric QT. METHODS This was a cross-sectional study of healthy adults aged 18–39 years. Isometric QT was assessed using fixed dynamometry (MedUp®). A 1-RM test was performed in the same setting. Age, sex and body composition using bioelectiral impedance analysis (Tanita, DC-430U) were collected. Physical activity was assessed by the Rapid Assessment of Physical Activity (RAPA). RESULTS Eighty-two participants were included (44 females, 54%). Isometric QT was 89 (77-132) Nm for females and 158 (133-187) Nm for males (p < 0.0001). There was a strong correlation between isometric QT and 1-RM (r = 0.85, p < 0.0001). The multi-linear regression model to predict 1-RM included sex, isometric QT and BMI (F (3, 78) = 60.819; p < 0.001; R 2 = 0.701). CONCLUSION Normative isometric QT values to quantify lower limb strength impairment and a preliminary equation using isometric QT to predict 1-RM and prescribe resistance quadriceps exercise training may inform pulmonary rehabilitation programs for a younger respiratory population. Validation of the 1-RM equation in clinical populations is needed.