This way of doing the leg press protects your knees against injury
Strength athletes who are worried that they are overtaxing their knee joints and are developing knee injuries could consider doing leg presses while holding a physio ball between their knees. According to a Brazilian study, which is soon to be published in the Journal of Strength and Conditioning Research, this version of the leg press stimulates precisely the muscle group that stabilises the knee joint and protects it against injury.
More stable knee joint
When strength athletes start to develop knee problems it's usually patellofemoral pain syndrome (PFPS). It arises when the rear side of the cartilage disc in the knee is overworked.
This may be the result of too little recovery, but it can also be due to a vastus medialis muscle that remains underdevelopped. If the lower part of the muscle group - the vastus medialis obliquus - is retarded in its development, the knee joint becomes less stable, and movements such as walking upstairs and squats exert more strain on the back of the kneecap.
The vastus medialis obliquus is activated during the last bit of the movement of stretching your legs out completely. The leg press is an excellent exercise for the vastus medialis obliquus, but the Brazilians wondered whether they could strengthen the effect of the leg press by making small adjustments.
The researchers got their subjects to perform leg presses in three different ways: on one occasion in the regular way; a second time with a physio ball clamped between the knees and once with an elastic band around their legs.
The researchers attached electrodes to the participants' legs so that they could measure how hard the muscles had to work.
The leg press performed with the physio ball gave the biggest stimulus to the vastus lateralis and the lower part of the vastus medialis. That means that this version of the leg press is suited to strength athletes who want to stabilise their knee joint.
By the way, the leg press with the elastic band provided the best stimulus to the rectus femoris.
Journal of Strength and Conditioning Research, May 2016, doi: 10.1519/JSC.0000000000001494. [Epub ahead of print].
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