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J Sports Med Phys Fitness. 2003 Mar;43(1):69-74.

Dynamics of muscle strength improvement during isokinetic rehabilitation of athletes with ACL rupture and chondromalacia patellae.

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Cybex Rehabilitation Center, Zagreb, Croatia.



To assess quantitatively dynamics and extent of the increase in muscle strength during isokinetic rehabilitation.



daily measurements of muscle strength; detailed testing at the beginning and at the end of rehabilitation.


Cybex Rehabilitation Center, Zagreb.


44 athletes (31 m, 13 F, age 16-35), 3 injury-defined groups: athletes with ACL rupture (non-reconstructed and reconstructed) and chondromalacia patellae.


all subjects underwent isokinetic rehabilitation on Cybex Orthotron KT2 device, using individually designed protocols (extension and flexion exercises, concentric muscle contractions, 15 treatments).


monitoring of daily progress on rehabilitation device and detailed testing on diagnostic device.


All patients showed considerable improvement. Muscle strength improved on average 141% (SD=110) in ACL-reconstructed group, 144% (SD=130) for chondromalacia patellae group and 150% (SD=74) for ACL-non-reconstructed group, comparing to initial strength. Dynamic status tested on Cybex Otrhotron diagnostic device prior and after rehabilitation strongly correlated with final progress monitored on the rehabilitation device.


Isokinetic rehabilitation is a quick and effective method in treating knee injuries in athletes. Both types of objective criteria have shown significant increase in muscle strength. The improvement of muscle strength was on the average 149% (SD=101), which is about 10% daily for 15 treatments. The greatest progress, 19% per day, occurred during first five days. The athletes were able to resume their sport activities as follows: patients from chondromalacia patellae group, and most of them from the non-reconstructed ACL group were back in competition within a month, while 75% from the ACL reconstructed group came back within 3 months, and the rest of them within 5 months.

[Indexed for MEDLINE]

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