Progressive overload (getting stronger)

We often say that progressive overload is key to bodybuilding. In other words, if our training program is not causing an increase in strength in the exercises we are using, it is not working.

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#1. What mechanisms contribute to strength gains?

We can increase maximum strength through a number of different adaptations, including: [1] coordination improvements, [2] reductions in antagonist coactivation, [3] increases in motor unit recruitment, [4] hypertrophy, [5] increases in tendon stiffness, and [6] increases in lateral force transmission. Yet, it is likely that most mechanisms except for hypertrophy and reductions in antagonist coactivation reach a plateau after a few years of training with easily-coordinated, stable exercises (obviously, coordination improves for many years in free weight movements). This means that hypertrophy is closely linked to strength gains in more advanced bodybuilders.

#2. How important is exercise selection if getting stronger is critical?

Some reductionist commentators have seized upon the idea that getting stronger is the key to long-term bodybuilding success and claimed that we can therefore discard all knowledge about exercise biomechanics and just do the big three exercises (squat, bench, and deadlift) because that is all that is necessary to get strong. This idea fails to take into account that part of the reason why strength is exercise-specific is that different muscles limit different exercises. For example, the two-joint muscles (rectus femoris, hamstrings, gastrocnemius, and triceps brachii long head) cannot contribute during those multi-joint movements and therefore will never grow unless some single-joint exercises are performed as well (read more).

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Also, some regions of muscles contribute far more than other regions of muscles to certain exercises depending on their [1] strength curve, [2] position of proximal and/or distal joints, [3] plane of motion, and [4] joint if training a two-joint muscle. When we change these factors, we change which muscle region is being developed maximally. So, if we want to maximize muscular hypertrophy across the whole body, we need a variety of suitable exercises and not just the three that happen to be used for a particular strength sport (read more).

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Conclusions

We often say that progressive overload is key to bodybuilding. In other words, if our training program is not causing an increase in strength in the exercises that we are currently using, then it is probably not working. While a range of adaptations can contribute to strength gains, if we select easily-coordinated and stable exercises and consider only lifters with several years of strength training experience, an increase in strength will necessarily be closely related to an increase in muscle mass, since the majority of the other adaptations reach plateaus much earlier in time. Nevertheless, that does not imply that strength as measured in a small number of benchmark exercises (such as the back squat, bench press, and deadlift) is an acceptable proxy for muscle mass. Indeed, there are two reasons why this cannot be the case. Firstly, the two-joint muscle problem demonstrates that two-joint muscles that act as antagonists at one joint and agonists at another joint in a multi-joint exercise are purposefully deactivated and are not stimulated. Thus, neither the rectus femoris, nor the hamstrings, nor the gastrocnemius are stimulated to grow by the squat. Similarly, the triceps brachii long head is not stimulated to grow by the bench press. Secondly, in accordance with the principle of neuromechanical matching, each exercise is usually limited by one muscle or one specific region of one muscle. While all of the muscle fibers linked to the accessible motor units of this muscle are stimulated to grow, those of the other muscles are not. Therefore, for maximum muscular development across the whole body it is essential to increase strength in a wide range of exercises that target different muscles and muscle regions.​

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