Validity and Reliability of the adapted Spring Balance as a Hand-Grip Dynamometer

Abstract

Reliable and valid evaluation of hand strength is important for determining the effectiveness of treatment strategies. Muscular grip strength is objectively measured by various types of dynamometers but some instruments are costly, time-consuming to use, or have questionable reliability. The various dynamometers that proved satisfactory over the years are expensive and scarce. Most physiotherapy departments in the developing countries and particularly Nigeria cannot boast of any of these dynamometers. This led us to develop the adapted spring balance (ASB) as a grip dynamometer. For any tool to be of great value in clinical assessment it must be valid and reliable. This study was therefore carried out to examine the validity and reliability of the new instrument (the ASB). Grip strength and endurance testings were conducted on forty (40) apparently healthy subjects (aged 22.38 ± 2.18 years) using both the ASB and the Jamar dynamometers. The data were analyzed for concurrent validity and test-retest reliability using the Pearson's product moment correlation method. The scores on the ASB correlated well with those obtained on the Jamar (grip strength, r = 0.766; grip endurance, r = 0.626) and it was found to have high test-retest reliability (grip strength, r = 0.808; grip endurance, r = 0.711). Linear regression equations were derived to enable the physiotherapist convert the ASB readings to approximate Jamar readings. This becomes very useful where there is the need to compare a patient's performance with standard norms. The results of this study indicate that clinicians can use the ASB dynamometer knowing that it is valid and reliable. The Journal of Medicine in the Tropics Vol. 9 (1) 2007: pp. 11-20