This study explored long-term stability of HHD measurements of isometric force production of upper- and lower-extremity muscle groups. A HHD was used to test 12 children with myelomeningocele, before and after a 23-day interval. This study attempted to eliminate bias with blind examiners; interrater reliability was assessed on each testing day for randomly selected muscle groups (5:458-465).
Results of this study demonstrated that most muscle groups had excellent stability. Upper-extremity muscle groups showed higher long-term stability than lower-extremity groups. The stability of test-retest measurements for most muscle groups was shown. Lower reliability of the left hip extensor measurements was concluded to be due to a lack of support of the leg while testing hip extensors. Stability measurements in paretic limbs was not found to be greater than in nonparetic limbs. The study concluded that HHD is a stable tool for measurement. It was suggested however, that support of the lower extremity during hip extensor tests, padding of the dynamometer end pieces, and use of a smaller, digital dynamometer might yield even more reliable results (5:458-465).
Wadsworth, Nielsen, Corcoran, Phillips, and Sannes (1992) studied interrater reliability of HHDs. One man and one woman were subjects; both had no neuromuscular deficits and a normal grade on manual muscle tests of five muscle groups. The raters were physical therapy students with previ