December 18, 2011

The Ultimate VMO Exercise

Overall Development vs Complete Development

The squat is strongly considered to be the ultimate leg builder for a few primary reasons:

·         It permits for the greatest loads to be used

·         It involves contribution from the greatest amount of lower body musculature

These two reasons alone are strong enough to outweigh any combination of reasons another exercise can offer, as no other exercise combines the amount of weight that can be used, with the amount of involved musculature, as much as the squat does. But just because the squat is capable of building the legs as a whole, more than any other movement, does not mean that the development is balanced.

Because relative continuous muscular tension is not required through a full range of motion, the contribution of the involved muscle groups, or even compartments of the same muscle groups, varies at different points throughout the range of motion, regardless of the exercise being performed. As a result, imbalanced development between the involved muscle groups, or compartments of the same muscle groups, can manifest by performing even the most complete movements.

As it relates to the squat, the vastus medialis oblique (VMO) head of the quad is the muscle, or compartment of a muscle, that is relatively undertrained in comparison to the rest of the involved musculature. The reasons for this are because the VMO (like almost all small, single joint muscles) has a slightly better angle of pull as compared to the rest of the quads during the final few degrees of extension, and is only really stretched (to which it responds by forcefully contracting) as the knee reaches full range flexion. Since the load is limited by how much force can be produced in the most disadvantageous position, the resistance is too light to optimally stimulate the VMO at the top of the movement, where it is most active. And since most people don’t squat low enough to optimally stretch the VMO, either because they lack the necessary mobility/stability, or would rather limit the range of motion as an excuse to use greater loads, they fail to get the depth necessary to optimally stretch the VMO for it to be recruited. So, unless deliberately using supramaximal loads through a very limited range of motion, with the specific purpose of overloading the VMO, it is relatively undertrained.

Fortunately there are 3 modifications that can be made to account for an imbalanced VMO, and they are:

·         Front load the body to promote a more upright posture

·         Elevate the heels to offset the center of gravity

·         Double the time under tension by performing a double contraction

Front Squat vs Back Squat

The lower back, and its level of contribution, is the only major glaring difference that separates squatting with the bar loaded on the back, or front of the body. With the bar on the back side, it’s possible to compensate for a relative weakness of the quads, glutes, or hamstrings, by leaning forward to distribute a greater percentage of the load onto the lower back. For obvious reasons, this is not possible with the bar on the front side, thus minimizing the lower back’s involvement, meaning that the only muscles available to lift the weight are the prime movers. Since the muscles of the thighs (primarily the hamstrings) have to make up for the limited contribution from the lower back, the front squat could be considered a superior leg developer.

*While the lower back heavily contributes to the squat, and can often become a limiting factor, it is the upper back that can end up limiting front squat performance, as it is needed as much as the lower back, if not more, to help stabilize the bar so that the movement can be performed. As a result, high rep front squats are ill advised, meaning the front squat is best trained with the use of heavy weights which fatigue the muscles without a lengthy time under tension in the first place. To make up for the reduced volume that accompanies heavy weights, simply perform more sets.

Heels Elevated vs Flat Footed

When squatting, the center of gravity shifts backwards beyond the base of support, and if mobility is limited at either the hip, or the ankle, balance is compromised. To account for the lack of mobility, the body will instinctively shift more of its weight forward, onto the toes, by elevating the heels, in attempt to reposition the center of gravity over the base of support. By pre-elevating the heels and standing on a pair of 5, or 10 lbs. plates, or even something as simple as a ‘2x4’, the center of gravity is offset slightly forward to account for the slight backward shift which takes place during squatting, thus facilitating greater depth when squatting (which is needed to stretch the VMO) due to greater mobility, and stability. Offsetting the center of gravity in this way also puts the posterior lower body muscles in a position of disadvantage, very much the same way the front squat limits lower back involvement, thus leaving the quads to make up for the limited contribution from the glutes and hamstrings.

Double Contraction Reps vs Traditional Reps

Since the resistance is generally too light at the joint angle in which the VMO has its best angle of pull (the final few degrees of extension), because it is limited by how much force can be generated at the joint angle in which the sum of the involved musculature is at its weakest, a traditional squat rep fails to provide the necessary tension to optimally stimulate the VMO. However, since the VMO is stretched as the knee reaches full range flexion, which happens to be the joint angle limiting the load that can be used, the amount of time spent in this range increases the amount of time in which the VMO is stretched under load, and this can positively stimulate the muscle to grow. This is best achieved by performing a double contraction – lowering all the way down, rising up slightly then pausing, then lowering once more before coming all the way up to finish the repetition.

Come One, Come All

Each modification can be used separately, as each one will fill in the gaps left from full range of motion squatting, or pair more than one together to create a hybrid movement aimed at strengthening the VMO. However, the combination of each modification can be used to create the ultimate VMO exercise – the heels-elevated, double contraction front squat!

Here are the rest of available combinations:

·         Heels-elevated double contraction back squat

·         Heels-elevated front squat

·         Heels-elevated back squat

·         Double contraction front squat

·         Double contraction back squat

If you have any questions about the VMO and how to modify an exercise to help develop it, feel free to contact me at I'm available for online consulting and personalized program design, as well as one on one training if you are located in the Greater Toronto Area (GTA).

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