Parameters of knee isokinetic dynamometry in individuals with acromegaly: Association with growth hormone levels and general fatigue

BACKGROUND: Individuals with acromegaly (IwA) may have alterations in skeletal muscles. Isokinetic testing is the standard method to assess muscle performance through objective, reliable, and reproducible measures. OBJECTIVES: To assess knee muscles performance of IwA with active and controlled disease and to correlate the findings with hormone levels, handgrip strength (HGS), general fatigue, and quality of life. METHODS: Sixteen men with acromegaly (MwA), 21 women with acromegaly (WwA), and 21 healthy controls (nine men and 12 women) underwent knee isokinetic dynamometry at 75 and 240 degrees/s as well as isometric dynamometry to assess HGS. The subjects were also assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale, the Fatigue Impact Scale (FIS), and the Acromegaly Quality of Life Questionnaire (AcroQoL). RESULTS: Compared with healthy controls, MwA and WwA exhibited significant reductions in the peak moment (PM), maximum work repetition, and total work for both extension and flexion at both angular velocities. There were significant differences for the agonist/antagonist ratio at 75 degrees/s in MwA (44% for active disease vs. 53% for controlled disease vs. 67% for the control group; P = 0.0002) and in WwA (48% for active disease vs. 58% for controlled disease vs. 66% for the control group; P = 0.0003). These patients also exhibited decreased HGS values and FACIT-F scores and increased FIS scores compared with healthy controls. There were significant correlations between measures obtained by isokinetic dynamometry, growth hormone (GH) levels, HGS values, and scores on the general fatigue questionnaires. However, GH levels were more strongly correlated with the isokinetic variables in MwA than in WwA. CONCLUSIONS: MwA and WwA exhibit decreased muscle performance in the upper and lower limbs, as well as excessive imbalances between the PM of the hamstrings and quadriceps. In addition, poorer muscle performance is associated with higher levels of GH and increased general fatigue. High GH levels have a more negative impact on the isokinetic parameters in MwA than in WwA.