Plantar flexor muscle function in open and closed chain

In the present study, the torque or work produced during isometric, pure co ncentric and eccentric-concentric plantar flexions, performed in sitting, s tanding and prone were measured. The electromyographic (EMG) activity was m easured from the soleus, gastrocnemius medialis, tibialis anterior and rect us femoris muscles. The isometric tests showed the highest torques in the s tanding test. The rectus femoris and gastrocnemius activities were lower in the prone than in the standing test. The sitting test showed lower activit ies in all muscles of the lower leg compared with the standing test. No dif ferences in work between the prone and sitting tests were found during the concentric phases. Higher rectus femoris activity in the eccentric-concentr ic test and lower activity in the triceps surae during the concentric phase s were seen in the sitting compared with the prone test. We conclude that t ests of overall functional ability should be performed in the standing posi tion while specific tests of the plantar flexors should be performed in the prone position.