This is the latest study by Jack Hickey and colleagues published a few weeks ago. Jack is part of the Hamstring Injury Group in Australia headed by Dr Anthony Shield and David Opar. Their group have grown and they collectively have produced a major bulk of the latest hamstring injury research in recent years.
Open access: NO
Date: Late Oct/Early Nov 2017 (can’t seem to find the exact date)
The most common types of knee flexor strength testing in hamstring strain injuries include isokinetic dynanometry, and the more recent nordbord which measures mainly eccentric strength by performing the nordic hamstring exercise. Dr Anthony Shield is also one of the inventors of the nordbord, which provides football clubs a more mobile and practical equipment compared to isokinetic dynanometry.
This new apparatus created by Jack and colleagues also employs similar principles to the nordbord as far as I understand, by using load cells on something like a suspension trainer equipment, and it measures forces through these load cells, which the nordbord also uses through the leg hooks on the equipment. They have named this new apparatus the HamSling. And of course it’s much easier to understand by looking at a picture of it (I found this picture shared by Jack on twitter):
You can see the person in the picture performing a single leg eccentric slider exercise on the HamSling.
“Knee flexor strength is a key variable when dealing with hamstring strain injury (HSI) and methodologies of objective measurement are often limited to single exercises.”
“To establish test re-test reliability of a novel apparatus measuring knee flexor strength during various hamstring exercises; to investigate whether these measures detect between-leg differences in males with and without history of unilateral HSI.”
“Twenty males without and ten males with previous unilateral HSI participated. Isometric knee flexor strength and peak rate of force development (RFD) at 0/0, 45/45 and 90/90 degrees of hip/knee flexion were measured, as well as force impulse during bilateral and unilateral variations of an eccentric slider and hamstring bridge, using a novel apparatus.”
“Moderate to high test re-test reliability was observed for isometric knee flexor strength (ICC = 0.87 to 0.92) and peak RFD (ICC = 0.87 to 0.95) across three positions and mean force impulse during the eccentric slider (ICC = 0.83 to 0.90).
In those with prior HSI, large deficits were seen in the previously injured leg compared to the contralateral uninjured leg for mean force impulse during the unilateral eccentric slider (d = -1.09, 90% CI = -0.20 to -1.97), isometric strength at 0/0 (d = -1.06, 90% CI = -0.18 to -1.93) and 45/45 (d = -0.88, 90% CI = -0.02 to -1.74) and peak RFD at 45/45 (d = -0.88, 90% CI = -0.02 to -1.74).”
“The novel apparatus provides a reliable measure of isometric knee flexor strength, peak RFD and force impulse during an eccentric slider, with deficits seen in previously injured hamstrings for these measures.”
Jack spoke to David Pope just about two weeks ago on the Physio Edge podcast talking about his recent work, this included, and other exciting stuff that he has been working on, which includes an accelerated hamstring injury rehab programme! Some of the very cool stuff they found was that we can get most patients doing eccentrics pretty early on, rather than the typical rehab protocol that usually includes them during late phase rehab. Of course there are certain criteria to be met before progressing to the different eccentric loading exercises. Find out more by listening to the podcast.
Jack also did a short presentation for one of the free sports injury videos created by Clinical Edge. He also spoke about some of his research findings in that presentation, I would recommend watching that video.
Unfortunately this study is not open access, however by listening to Jack talk about it in the podcast and video presentation, you can get quite a good idea of their findings. And we should be expecting a lot more cool research from Jack and his team soon.