<b>Back Squat v Front Squat</b>

Which is better for the knees?

Thinking in terms of loads and forces, there are compressive forces and shear forces to be considered here. When considering the knee, a compressive force will squeeze the cartilage.

<b>The Knee</b>

Firstly with regards to the knee during the squat there is a lot of evidence out there about what forces are being transferred through the knee joint and its structures. Things that need to be considered when referring to research are the health and biomechanics of the individuals, circumstances of the project and the limitations or variables of specifics to the research study. The difficulty is then for the reader to decipher what this may indicate for them as an individual. The translation of this information is often where things become distorted so I will try to be as precise as I can be with the information I have gathered, while generalising with safety in mind.

Quadriceps, hamstring and gastrocnemius activity increases as knee flexion increases, which supports athletes with healthy knees performing the parallel squat (thighs parallel to the ground) between 0 and 1000 knee flexion. It is also demonstrated that the parallel squat is not necessarily a problem to knee health.

For those of you with healthy knees, the parallel squat is recommended over the deep squat (A2G or squatting down as far as possible until the posterior thighs and lower leg make contact with each other) because the risk of injury to the menisci and cruciate and collateral ligaments is likely to increase during the deep squat. The squat itself does not compromise knee stability though and in fact when performed correctly with good biomechanics, it can enhance stability. Large decelerations during the squat generate huge forces through the knees during the decent of the squat which is why this part of the movement should be performed in a slow and controlled manner to avoid higher risks of injury.

For those of you who find yourself ‘forward flexing’ or ‘trunk tilting’ the greater hip flexion has been shown to eliminate ACL stress, as stated above, mainly due to the increased hamstring activity. This could therefore indicate quadriceps dominance (Hewitt 2004). In other words the hamstring to quadriceps ratio is likely to require some form of conditioning of the hamstrings to regain a balance. What is paramount is what type of conditioning work and what must first be established is the reason for the imbalance in the first place.

At 60deg of knee flexion the forces in the knee joint change from greater posterior force to a greater anterior shear force which increases throughout the ascent. Hence performing squats at knee flexion angles of less than 900 will minimise the risk of knee injury.

Fry et al (2003) did a study looking at the effects of allowing the knees to move over the toes. This study found that while the NSCA cite the knees should be kept from moving forwards over the toes or to keep the trunk in an upright posture, in order to optimise the forces involved on all the joints, it may be a good thing to allow the knees to travel ‘slightly’ over the toes. This allows for a more even distribution of load through ankle, knee, hip and spine.

<b>Squat width with regards to forces at the knee;</b>

When considering the width of the squat it has been demonstrated that the wider squat has been shown to generate 15-16% significantly greater compressive forces through the knee joint than a narrow stance, McCaw et al (1999).Thus a narrow stance is a better choice if you wish to reduce the risk of compressive forces going through the knees.

<b>To summarise on these points; </b>

For those with healthy knees a greater angle of knee and hip flexion is ok so long as the loads are not heavy. Periodisation techniques should always be used when performing the squat, in that the training is divided into light, medium and heavy cycles throughout the year. This also enables an individual to perform a variety of squat depths.

<b>Next time: The Squat Part 4/6 – The Foot &amp; Footwear</b>

Firstly I would just like to clarify part 4 relates to foot position not foot width (see part 3 for width)

Do you worry about adding squats to your clients programme?

Do you struggle to squat?

Do you use the leg press because squatting hurts your back?

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