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The purpose of this study was to examine the test-retest reliability for the real time ultrasonic measurement method that is used to determine the stiffness of the Achilles tendon. Twenty-one healthy men and women aged 20-50 years took part in the study. The subjects underwent three identical test sessions held seven days apart. The lengthening of the tendon during maximal isometric plantar flexion was determined using ultrasonography. A dynamometer was used to measure torque output during isometric plantar flexion. The relationship between the muscle force and the elongation of the tendon was calculated to become a measure of the stiffness of the Achilles tendon. The ICC for the stiffness of the right and the left Achilles tendon was 0.80 and 0.82 respectively, indicating a good reliability. The results demonstrate that this technique is reliable for the evaluation of the elastic properties of the Achilles tendon. This may be clinically important in the assessment of tendon properties.

Objective: To determine the influence of ageing on lean muscle area and isometric and concentric and eccentric muscle strength in the upper and lower extremity in a cross-sectional study design. Subjects and methods: Lean muscle area and maximal muscle strength (isometric and isokinetic, 60degrees and 120degrees/s) of both upper and lower extremity were assessed of 45 men and 56 women (20 to 89 years). Results: One-way variance analysis and regression analyses revealed a parallel decline with age in both sexes for maximal muscle strength. The decline in maximal muscle strength from age 60 was 34 to 45% in men and 11 to 32% in women in the arms and 40 to 47% in men and 37 to 45% in women in the legs. Isometric, concentric and eccentric contractions showed a similar decline in ageing in both sexes. There was a better maintenance with age of the strength in the arms than in the legs (p < 0.01) and at 120degrees/s than at 60degrees/s (p < 0.05). Conclusions: The present findings suggest a parallel decline in lean muscle area and strength and similar losses in isometric, concentric and eccentric strength with increasing age.

The aim of this study is to determine the rest-retest reproducibility for measuring the peak torque and the total work of the protractors and retractors of the shoulder girdle according to the isokinetic concentric muscle action. The tests were performed in two sessions at a 7 day interval. Nineteen healthy volunteers were included. Evaluation was carried out with a Biodex System 3 isokinetic dynamometer using the closed chain attachment. The protocol consisted of 5 isokinetic concentric contractions at a linear velocity of 12.2 cm/sec and 10 repetitions at a velocity of 36.6 cm/sec. The shoulder girdle protraction and retraction movements were performed with the arm horizontal in the scapular plane, which is 30 ◦ anterior of the frontal plane. Intraclass-Correlation-Coefficients were calculated to establish day-to-day repeatability. Results show an excellent reproducibility for isokinetic peak torque at both velocities on the non dominant side (ICC 0.94-0.96) and very good to excel lent reproducibility on the dominant side (ICC 0.88-0.92). Reproducibility was also very good for total work values in both movement directions at both velocities (ICC 0.82-0.89). The results indicate that isokinetic protraction and retraction strength evaluation is a reliable tool in the evaluation of shoulder girdle muscular performance. This may be clinically important in the assessment of shoulder dysfunction.