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

14. Wadsworth, C. T.; Nielsen, D. H.; Corcoran, D. S.; Phillips, C. E.; Sannes, T. L. Interrater reliability of hand-held dynamometry: Effects of rater gender, body weight, and grip strength. JOSPT 16(2):74-81; 1992.

2. Andersen, H. Reliability of isokinetic measurements of ankle dorsal and plantar flexors in normal subjects and in patients with peripheral neuropathy. Arch. Phys. Med. Rehabil. 77:265-268; 1996.

In a study testing 106 men and 125 women (aged 20 to 79 years), with no known neuromuscular, musculoskeletal, or cardiovascular pathology, HHD was used, twice. Results showed that measurements were reliable. Only for the case of ankle dorsiflexion measurements of the nondominant side, was there a difference found in the forces of a first and second measurement. All intraclass correlation coefficients were found to be greater than .94. Conclusions for this study also noted that HHD reliability is dependent on the strength of the tester; the clinician must be strong enough to hold against the patients' efforts (4:26, 28, 31).

11. Nicholas, J. A.; Sapega, A.; Kraus, H.; Webb, J. N. Factors influencing manual muscle tests in physical therapy. J. Bone and Joint Surg. 60-A(2):186-190; 1978.