Evaluation of the Numeric Rating Scale for perception of effort during isometric elbow flexion exercise

• Published in: European journal of applied physiology Vol. 112; no. 3; pp. 1167 - 1175
• Main Authors: Lampropoulou, Sofia, Nowicky, Alexander V.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-03-2012; Springer; Springer Nature B.V
• Subjects: Adolescent; Adult; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Elbow - physiology; Elbow Joint - physiology; Electromyography; Exercise - physiology; Female; Fundamental and applied biological sciences. Psychology; Human Physiology; Humans; Isometric Contraction - physiology; Male; Middle Aged; Muscle Fatigue - physiology; Occupational Medicine/Industrial Medicine; Original Article; Perception - physiology; Perceptions; Physical Exertion - physiology; Range of Motion, Articular - physiology; Ratings & rankings; Reproducibility of Results; Research Design - standards; Sports Medicine; Validity; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Weights and Measures - standards; Young Adult; Fatigue; Correlation; Scale sensitivity; Numeric Rating Scale; Perception of effort; EMG; Physical exercise; Human; Evaluation scale; Effort; Electrophysiology; Sensitivity; Perception; Electromyography; Elbow
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-011-2074-1

The aim of the study was to examine the reliability and validity of the numerical rating scale (0-10 NRS) for rating perception of effort during isometric elbow flexion in healthy people. 33 individuals (32 ± 8 years) participated in the study. Three re-test measurements within one session and three weekly sessions were undertaken to determine the reliability of the scale. The sensitivity of the scale following 10 min isometric fatiguing exercise of the elbow flexors as well as the correlation of the effort with the electromyographic (EMG) activity of the flexor muscles were tested. Perception of effort was tested during isometric elbow flexion at 10, 30, 50, 70, 90, and 100% MVC. The 0-10 NRS demonstrated an excellent test–retest reliability [intra class correlation (ICC) = 0.99 between measurements taken within a session and 0.96 between 3 consecutive weekly sessions]. Exploratory curve fitting for the relationship between effort ratings and voluntary force, and underlying EMG showed that both are best described by power functions (
y
 = 
ax
b
). There were also strong correlations (range 0.89–0.95) between effort ratings and EMG recordings of all flexor muscles supporting the concurrent criterion validity of the measure. The 0-10 NRS was sensitive enough to detect changes in the perceived effort following fatigue and significantly increased at the level of voluntary contraction used in its assessment (
p
 < 0.001). These findings suggest the 0-10 NRS is a valid and reliable scale for rating perception of effort in healthy individuals. Future research should seek to establish the validity of the 0-10 NRS in clinical settings.