Muscle imbalance and in particular of the legs is considered as a risk factor for injuries in football players. To evaluate muscle strength and imbalances most practitioners use isokinetic dynamometry. However, there are a number of factors that limit the use of isokinetic dynamometry in a large number of players and thus threaten its practical applicability. The high cost of the isokinetic device, the time required to test one player (15-20 min) and the skills required by the examiner are some of them.
Hand held-dynamometers are simple devices that require no high expertise from the experimenters. Rod Witheley and his colleagues from Aspetar Orthopaedic and Sports Medicine Hospital, Qatar, published a very nice study few days ago which compares novel hand-held dynamometry tests results of knee flexion and extension with isokinetic dynamomery. Their study population was 216 male professional football players.
Their results showed:
· Medium to high correlation between hand-held dynamometry measures and results from isokinetic dynamometry.
· Reliability for the eccentric hamstrings, isometric hamstrings, and isometric quadriceps measures was excellent with the hand-held dynamometer.
Another strong point of the study is thepublication of normative data for hand-held dynamometry measures from a large sample of professional football players.
In my opinion, the novel measures with hand-held dynamometer described in the paper of Whiteley and colleagues will help a lot in the evaluation of football players since:
· Measures are reliable and take only 4-5 min
· The cost of the hand-held dynamometer is low, and
· No specific skills are required
Whiteley et al (2012). Correlation of isokinetic and novel hand-held dynamometry measures of knee flexion and extension strength testing. Journal of Science and Medicine in Sport, Mar 15. [Epub ahead of print]