Infographic & Discussion- van Dyk et al. (2018)- Interseason variability in isokinetic strength

Aims- 1) Describe season-to-season variability of isokinetic strength testing. 2) Investigate the relationship between isokinetic muscle strength testing and eccentric strength testing

Methods- Data prospectively collected from 288 players in the Qatar Super League. Players underwent full pre-season testing involving isokinetic and NHE strength testing.

Results- 1) Poor correlation between isokinetic eccentric torque and NHE peak force. 2) No correlation between limb strength imbalances with both tests.

Conclusion- 1) Substantial individual season-to-season variability was identified for isokinetic strength measurements. 2) The results from standard (isokinetic) and novel (NHE) eccentric hamstring strength testing were poorly correlated.



This latest paper from van Dyk et al. (2018) took my interest due to it’s assessment of NHE strength and how that correlates to isokinetic strength testing.  At first it was a bit of a surprise to see that there was a poor correlation shown within the tests. However, upon further consideration of this actually this difference is to be expected. The different biomechanical nature of the two tests means that it is unlikely that comparisons can be made, with the isokinetic test performed in hip flexion and unilaterally compared to the NHE which is performed with a neutral hip and bilaterally. The authors also highlight how the uni/bilateral difference between the exercise may explain why asymmetries are also not transferable.

The other take home message from the paper is that there was substantial individual season-to-season variability between isokinetic testing. I would suggest that this is to be expected as the players develop an advancing “training age” from participation in the sport, although there is no record of the football, or gym based training performed by the athletes so this opinion cannot be supported by the data.

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