Maximum Muscle Activation Training

When it comes to selecting which exercises for each muscle group to include in our workouts, we all have our preferred movements that we swear give us the best results or allow us to ‘feel’ the muscle being isolated and engaged. But are we actually selecting the correct exercises to help us capitalise on our workouts?

If only there was a way to measure just how much muscle is being activated during certain exercises.

Well now there is! Introducing Electromyography (EMG)! The process of measuring the quantity of electrical signals sent by motor neurons in order for a muscle to contract.

In other words, EMG measures the amount of force the body is attempting to exert on a muscle, which provides scientists (and now us too) with an indication as to how active a muscle is during a specific movement or exercise.

How EMG Works

EMG testing involves taping electrodes to the skin across a muscle which measure the speed and strength of the electrical signals between two points. The greater the quantity of electrical signals detected, the greater the force required to perform a movement, and therefore the greater muscle activation.

In order to make meaning from the values collected, scientists must know what the baseline amount of force is able to be generated, or the baseline amount of electrical signals are able to be sent in the first place. This sets the calibration for the EMG test and is called the Maximum Voluntary Contraction (MVC) value. In order to obtain this measure, the subject must position their body in the optimal position to allow a specific muscle to generate the most powerful ‘squeeze’ it possibly can during an isometric contraction. Once this value is obtained, EMG has the ability to measure how active each muscle is during different exercises by comparing it to the value obtained from the MVC test as a percentage. Where values exceed 100, this indicates that a higher number of electrical signals are detected during the exercise when compared to the amount detected during the isometric contraction. This is common during compound movements where multiple muscle groups participate.

EMG analysis can provide valuable information to a broad variety of athletes. It allows muscle & nerve disorders and poor motor neuron activity to be detected to reveal information about a person’s biomechanics and kinesiology. It has also recently been given a lot of attention in the fitness community, proving useful to both bodybuilders and performance based athletes.

In obtaining results from EMG analysis, two separate measures can be recorded. The first is the “peak”, which refers to the greatest observed value of electrical activity that occurs at any point during a movement. This is useful for sports or performance based athletes as it can show when maximum force occurs during a movement, and which exercises should be performed to increase muscle strength. The other useful measure is known as the “mean”, which represents the average level of electrical activity that occurs within a muscle over the entire duration of the movement. This information is valuable for bodybuilders with hypertrophy related goals who aim to optimise the amount of time muscles are under tension, or anyone who wishes to know which movements require the greatest amount of activity or effort to complete.

Implementing The Results Of EMG

A comprehensive study undertaken by certified strength and conditioning specialist, Bret Contreras, provides an in-depth analysis of a variety of common exercises undertaken when targeting specific muscle groups. The following information has been separated based on which exercise yields the highest value for both the mean and the peak value of electrical signal detection. Whether you are interested in optimising your muscle time under tension, or producing maximal force, the following data can help you shape your weekly training regime.

Chest

Looking at the mid pec, the DB Bench Press, Guillotine Press and DB Fly consistently rank at the top in terms of activation. All these movements have a very similar motor pattern where the elbows move behind and to their most distal (furthest) position from the midline of the chest. This gives credence to bodybuilders typically adopting a wider grip than powerlifters on all pressing movements, allowing the elbows to move to their most distal point emphasizing a greater stretch across the pec. Similarly, the lower pec responds best to exercises that place an emphasis on a full stretch across the pec, which is not unreasonable due to the close synergy between the middle and lower portions of the chest.

Strangely enough, EMG infers that heavy powerlifting style bench pressing is not necessary, nor desirable, when the goal is maximal chest stimulation to promote muscle growth. It certainly appears that using multiple isolation-type exercises within a workout that strategically target the chest from a variety of different angles will reap the greatest results in terms of muscle growth.

Shoulders

The popularity of Face Pulls has certainly increased in recent years, however most would associate this exercise with maintaining shoulder health and integrity, along with activation of the rear delt. Surprisingly, based on the results of the study, the Band Face Pull topped the list for mean and peak values for both the middle and rear delt.

Biceps & Triceps

In comparison, the triceps responded most favourably to isolated movements, with Rope Extensions and Cable Extensions topping the list with the highest mean and peak values. Certainly the triceps receive plenty of activation during compound pressing movements and these results are no reason to completely dismiss these movements. However, the EMG activity does support incorporating movements that allow the triceps to reach a fully contracted position with minimal assistance from ancillary muscles such as the chest and shoulders.

Quads

Often forgotten, the adductors (inner thigh) are a huge contributor when it comes to impressive leg development. Typically squatting and leg pressing with a wider stance will help to engage the adductors to a greater degree, however there are a number of underused exercises that can be utilised to specifically target the adductors. The Romanian Deadlift tops the list for highest peak activation, while Single Leg Gliding Leg Curls are the top pick for highest mean adductor activation.

Hamstrings, Glutes & Calves

For the hamstrings, the results suggest the greatest muscle activation is achieved through explosive compound movements like the Deadlift and Rack Pull. Interestingly, the Stiff-Legged Deadlift did not make an appearance at the top of either the mean or peak lists, which suggests that the movements that typically cause the most soreness or muscle discomfort may not be the most effective in terms of muscle activation.

Overall the calves respond best to Heavy Calf Raises as opposed to lighter more explosive calf raises or paused calf raise variations. It is typical for most people to tack on a couple of half-hearted sets of calf raises at the end of a leg workout, generally with light loads and lots of reps in the shortest time possible; these results certainly support re-thinking and prioritizing calf training with heavy sets in the 6-12 rep range and a focus on increasing the amount of weight used from one session to the next.

Back & Traps

The Dumbbell Bent Over Row stimulates the greatest mean and peak activation across the board for the mid back and traps. In comparison to the barbell row, using dumbbells allows for an increased range of motion as the elbow can track further behind the torso, which would appear to provide an advantage for increasing muscle activation.

The upper traps receive the greatest activation through a combination of heavy shrugs and, surprisingly, from most lateral raise and shoulder pressing movements.

Limitations

With all scientific experiments come some form of limitations and factors that must be noted when considering the accuracy and personal applicability of the data. In this instance, the data was produced for bodybuilding purposes, therefore the amount of weight selected to perform each exercise enabled at least five successful repetitions to be completed. For those who participate in strength training or powerlifting, the data may not accurately represent muscle activity, especially when attempting 1RMs.

It must also noted that each individual is unique. Individual biomechanics and genetic makeup will dictate just how motor units activate and perform, and therefore which muscles are used and to what extent. Individual differences surrounding anthropometry (differences in size such as height) will also influence how exactly movements are performed. For example, taller athletes may use more gluteus muscles during a squat than shorter athletes, as they have further to travel from the starting position. 

Chest and Triceps: