Most strength coaches like to see good technique being used in an exercise, especially in the popular, multi-joint exercises that are often used to prepare athletes for sport.
It is often said that good technique is helpful because it reduces the risk of injury. However, technique also affects hypertrophy, for two reasons.
Firstly, it affects our ability to deliver a mechanical stimulus to the muscle we are trying to train. Secondly, it affects our ability to quantify and therefore achieve progressive overload.
How does exercise technique affect the mechanical loading stimulus?
Exercise technique affects body and limb positions. This in turn affects the turning forces (torques) that are required at each joint, and it also alters the points in the exercise range of motion where peak turning forces (torques) are required.
Each of these changes can affect the mechanical loading stimulus that a muscle experiences during strength training.
Changes in the turning forces (torques) that are required at each joint shift the load of the exercise from one joint onto another (and therefore from one muscle group to another). This can affect which of the muscle groups in an exercise is the limiting factor for exercise performance, and therefore which gets closest to full motor unit recruitment at muscular failure, although the extent to which this matters is dependent upon the exercise.
For example, when we shift to doing a low bar squat instead of a high bar squat, we alter the horizontal distances of the hip and knee joints from the barbell at the bottom of the exercise, where it is hardest. In doing so, we shift part of the load of the exercise from the knee extensors to the hip extensors. Since the knee extensors seem to be the limiting factor in the squat, this allows us to lift a slightly heavier weight with this technique. However, since the knee extensors remain the limiting factor in both exercise variations, the stimulus to the quadriceps is likely identical, but the primary hip extensor in the squat (the adductor magnus) gets to work a little bit harder whenever we use a low bar position.
Changes in the points in the exercise range of motion where peak turning forces (torques) are required shift the point of peak contraction from one part of the exercise range of motion to another (and therefore from one muscle group or region of a muscle group to another, because of differences in internal moment arm lengths of the prime mover muscles and muscle regions at each joint). This affects which muscles or regions of a muscle experience the greatest loading in an exercise, which affects the subsequent muscle group hypertrophy, or regional hypertrophy that occurs.
For example, when we alter depth in the squat, we alter the contribution of each of the hip extensors at the bottom of the exercise, where it is hardest. Compared to a deep squat, partial squats shift the load of the exercise from the adductor magnus to the gluteus maximus.
Consequently, if we alter our technique from one workout to the next, or one set to the next, then this can interfere with our ability to quantify progressive overload, because different muscles or regions of a muscle will be contributing to the lift in each workout.
How do changes in exercise technique affect the mechanical loading stimulus?
Sometimes, our technique changes inadvertently during a set when we lift heavy loads or when we lift light or moderate loads under fatiguing conditions. When this happens, the new technique involves a different set of body or limb positions, and it often allows us to reduce the load on the muscle that was previously being worked hardest, while increasing the contribution of other muscle groups.
For example, lifters sometimes alter the bar position slightly on their back when squatting, shifting the position away from a high bar position and towards a low bar position, and they sometimes alter depth over a set, often squatting deeper in the early reps than in later reps. Shifts in bar position alter the proportional contribution of the hip and knee extensors, and shifts in depth alter the proportional contribution of each of the hip extensors.
Also, some lifters find that the squat becomes a “squat morning” as the load or effort increase. This causes a shift in the proportional contribution of the knee extensors to the hip extensors. This may mean that the load on the quadriceps is reduced to the point where the muscles are no longer maximally recruited, or it may mean that the quadriceps are maximally recruited, but load has shifted to the hip extensors to allow more reps to be done, as in the low bar squat above.
Ultimately, when shifts in technique occurs in a set, it is hard to know whether the muscle (or region of a muscle) that was originally being trained is continuing to work maximally (with a high level of motor unit recruitment), or whether it is being allowed to reduce its contribution so much that recruitment has reduced. This again interferes with our ability to identify whether progressive overload has really happened, or whether the increase in the weight or in the number of reps is a result of technique changes.
Can changes in single-joint exercise technique affect our ability to quantify progressive overload?
Changes in exercise technique that affect our ability to quantify progressive overload are not limited to multi-joint exercise. They can also occur in single-joint exercises, when range of motion is limited as a result of fatigue.
For example, many lifters find that the height that they can lift the dumbbells in a lateral raise decreases progressively over the course of a set, and it is hard to determine the point at which the height has dropped to the level where the rep should be considered a failure to achieve full range of motion. Monitoring progressive overload in this exercise requires both practice and discipline, to make sure that reps are done as close to the same height every time, and to stop the set when form deteriorates past a certain point.
Why is quantifying progressive overload important for hypertrophy?
Achieving progressive overload in each set is critical to long-term success when training for hypertrophy, because of the way in which muscle growth is stimulated.
If we perform sequential workouts with the same sets and reps and the exact same weight, the number of stimulating reps delivered to the muscle is smaller in the second workout, because we move further from failure in some or all of the sets, as a result of our strength gains. If we do this for several workouts in a row, the number of stimulating reps delivered to the muscle drops below the level necessary to achieve hypertrophy, and we stop moving forwards.
Quantifying progressive overload is therefore very important for monitoring our progress in a hypertrophy program. Only if we are increasing the weight or reps in each workout (while keeping technique the same) can we be sure that we are delivering the same number of stimulating reps to the muscle in each sequential workout.
If technique changes during a set, and allows us to perform additional reps that are not actually stimulating for the muscle we are trying to train, we could easily fool ourselves into believing that we are achieving progressive overload, when we are not. We could spend many weeks or even months performing workouts in which the weights and numbers of reps continue to increase, but the muscle remains the same size because the increases are occurring due to alterations in technique, and the muscle itself is not actually being challenged anymore.
Which exercises frequently lead to changes in exercise technique?
We all know that it is easier to maintain a constant technique in some exercises than in others.
Those exercises in which it is easy to maintain technique are valuable to use when training for hypertrophy, because they allow us to deliver all of our stimulating reps to the muscle (and region of a muscle) we are intending to train, and because they allow us to quantify the amount of progressive overload we are achieving.
In contrast, when we use exercises that permit shifts in technique, we open up the possibility that each set is providing a few stimulating reps to one muscle (or region of a muscle) and a few stimulating reps to another muscle (or region of a muscle). It is also very difficult to identify whether progressive overload is occurring, or whether we are just altering our form to do more reps or lift a heavier weight.
#1. Exercises in which it is easy to maintain form
In some exercises, it is fairly easy to maintain form when lifting heavy loads, or in the 5 reps before failure when lifting light or moderate weights (these conditions are essentially the same, as far as the mechanical loading stimulus is concerned). These exercises fall into two categories:
- Those with fixed movement patterns, and
- Those without fixed movement patterns, but where the weight tends not to change its bar path or range of motion when using heavy loads or working under fatiguing conditions.
Exercises with fixed movement patterns are those that do not allow the weight to be diverted from its intended path. Such exercises can only be performed on machines (excluding cable machines). In these exercises, regardless of how much effort you exert, it is fairly easy to maintain form. The leg press is a good example of this type of exercise. We cannot change the path of the weight in this exercise by altering our form.
Exercises without fixed movement patterns, where the weight *tends* not to change its bar path or range of motion when using heavy loads or working under fatiguing conditions, are harder to define. Even so, they are fairly easy to identify by observation. Good examples of this type of exercise include the bench press and deadlift.
As load or fatigue are increased in all of these exercises, the increased effort at slow speeds does not cause any substantial change in the way that the exercise is performed. The same ranges of motion are achieved, and the body positions throughout the lift remain largely the same. This means that we can be fairly certain that we have achieved true progressive overload when we improve our repetition strength during a workout in these exercises.
#2. Exercises in which it is difficult to maintain form
In a number of exercises, it can be hard for us to maintain the same form or range of motion when lifting heavy loads, or in the five reps before failure when lifting light or moderate weights (these conditions are essentially the same, as far as the mechanical loading stimulus is concerned).
Exercises in which form or range of motion are altered by the size of the weight or by the proximity to failure are often those that require momentum to accomplish the top part of the exercise. Such exercises have an incredibly steep strength curve, such that the bottom part is very easy but the top part is very hard. Consequently, as effort increases, it remains easy to perform the bottom part of the exercise, but the top part becomes very hard.
The dumbbell lateral raise is one example of this type of exercise. The height that the dumbbells reach decreases progressively over the course of a set, and it is hard to determine the point at which the height has dropped to the level where the rep should be considered a failure to achieve full range of motion. The barbell bent-over row is another good example. When using light or moderate loads, the bent-over row can be performed easily through its full range of motion, at least when fatigue is minimal. Yet, as effort is increased (either due to increasing load or fatigue), technique usually alters. Without a lot of practice and discipline, the exercise turns into a hybrid between a row and a power clean, so that more force exerted at the bottom of the lift can compensate for a lack of force at the top.
Exercises in which form or range of motion are altered by the size of the weight or by the proximity to failure also include exercises that have steep strength curves in the other direction, such that the top part is very easy but the bottom part is very hard, like the squat. Consequently, as effort increases, it becomes increasingly tempting to perform shallower and shallower versions of the exercise, since the top part remains very easy.
In both cases, when form alters during the set, it becomes hard to tell when a rep should be considered a failure, since it is nearly always possible to do “just one more” rep, albeit with progressively worse and worse form. Thus, without careful monitoring of technique, identifying whether progressive overload is happening from one workout to the next is nearly impossible.
What is the takeaway?
Technique affects hypertrophy, for two reasons. Firstly, it affects our ability to deliver a mechanical stimulus to the muscle or region of a muscle that we are trying to train, and secondly, it affects our ability to quantify progressive overload.
When shifts in technique occurs over a set, the muscle (or region of a muscle) that was originally being trained can reduce its contribution to overall force production such that its level of motor recruitment reduces, and it ceases to receive a stimulus with each stimulating rep, because other muscles or muscle regions are worked instead. This splits the stimulating effect of an exercise across multiple muscles or muscle regions, which will not be as effective as a more targeted approach.
If technique changes during a set, and this change allows us to do additional reps that are not stimulating for the muscle we are trying to train, we could easily fool ourselves into believing that we are achieving progressive overload, when we are not. We can address this by either selecting exercises that do not run the risk of altering their form or range of motion over the course of a set, and by carefully monitoring technique in those exercises that do.