Many times we hear in our environment that one should perform reps as explosively as possible in each repetition. This methodology has been recommended by authors who write articles for both hypertrophy and specific sports training purposes.
This theory is the one that maximizing the "explosiveness", one would totally activate the high threshold motor units (HTMU), which will lead to higher rates of hypertrophy and strength development (rate of force development, RFD).
In truth, there is not much evidence to show that explosive lifting improves athletic performance over controlled lifting. In fact, Bruce-Low and Smith wrote an entire article on this subject. I recommend that you see it, so we will provide a link to the article.
Moreover, the results of Hay et al., Who measured joint torque in three male subjects while performing biceps curls, also seem to support this view. Hay and cols. found that with short lifetimes (<2 sec), a very small joint torque was required to move the weight through most of the range of motion (ROM), since after the start of movement, the weight continued moving under his own acquired speed. Therefore, fast movements do not provide as much muscle tension as slow movements through most of the ROM, indicating that faster repetitions, such as those performed with 'explosive' exercises, cannot produce increases in optimal strength to through the complete ROM of a muscle.
This would also apply to hypertrophy, several muscles involved in the initial phases of the lift can be demanded very well during explosive movements while other muscles involved at the end of the lift cannot be demanded very well.
It has been shown that isometric protocols are "rank-specific", which means that they only work very well for a certain range of motion, not for the entire movement. From the previous investigation, we observed that different speeds of the repeats are also "rank specific."
Finally, EMG data shows that certain exercises totally require several muscles in different portions of the lift as well. For example, a squat shows more activation of the gluteus in the lower part of the movement while a hip pull shows more activation of the gluteus in the upper part of the movement. For this reason, I call the squat a "stretch position" exercise and the hip thrust a "contracted position" exercise.
Contrary to popular opinion, the same muscles are not activated in the same proportions throughout a movement, and different portions of the muscles are also worked through different ranges. In Supertraining, Siff explains the erroneous, yet popular, view that:
- The same movement is always produced by the same muscles
- The same muscles always produce the same movement
- The same muscles are dominant throughout the entire range of motion
- The muscles only act as active tissues
- The muscles only act as mobilizers or stabilizers
- Muscles are the only important tissues that control movement
These misconceptions are simply not true. Some muscles do not start until the ratios of levers and length-tension change during a survey and are also impacted by the directional load vectors. This is especially true in compound movements and movements involving the hip joint. In fact, some muscles may have opposite roles along a range of motion. This is called "muscle action reversal." A first example is that of the adductors; they are extensor muscles of the hip when the hips flex and flexors of the hip when the hips are extended.
In this way, if you want to maximize hypertrophy and / or the transfer of strength training to sport, you should consider what "range" the muscles are activated by each exercise and type of repetition. In specific sports training, it is not just about "movements"; it's about muscles, joint angles, load vectors, energy systems, transfer through other areas of the body, etc.
In sports, you are powered by movements such as a long sprint or jump, so you need to be strong and powerful in all ranges.
There are benefits and disadvantages to each type of repetition and exercise. I will simply list some 'pro' and 'against' from a variety of common types of repetitions:
Benefits of explosive lifting: greater strength in a stretched position, better method to start strength, better method for the rate of strength development, possibly more tissue damage due to increased stress in the stretched position - better for hypertrophy in beginning muscles the movement
Disadvantages of explosive lifting: the deceleration in the upper part in the contracted position, not so good for the end of the force, not so good to produce constant tension that can be critical for hypertrophy
Benefits of controlled lifting: greater force throughout the full range of motion, no "help" from the momentum that requires considerable muscle tension in all ranges, plus "constant tension" that would lead to occlusion and hypoxia - greater for hypertrophy
Disadvantages of controlled lifting: slow movement speed, submaximal acceleration
The benefits of manageable resistance (bands and chains): acceleration, good method for the force of completion
The disadvantages of the manageable resistance (bands and chains): submaximal stress in the stretched position compared to the straight weight, less stable, the "force curve" does not coincide
Benefits of weight releasers: accented eccentric actions
Disadvantages of weight-releasing: it only works for a repetition
Benefits of isometry: can improve any specific area of a particular survey
Disadvantages of isometry: specific range; it does not transfer well to other ranges, it can interfere with muscle elasticity and power output
Benefits of eccentric actions: very good for agility, deceleration, and hypertrophy
Disadvantages of eccentric actions: extreme pain, does not always transfer perfectly to the concentric force, sometimes requires an assistant
Benefits of ballistic actions: good for the rate of strength development and reactivity / elasticity
Disadvantages of ballistic actions: not very good for hypertrophy or maximum strength
Benefits of only concentric exercises (ex: sledge thrusts): reduced pain
Disadvantages of only concentric exercises (eg, sled thrusts): no eccentric phase, suboptimal for hypertrophy
Benefits of exercises in a stretched position: improved starting power
Benefits of exercises in contracted position: improved final power
Benefits of quasi-isometric eccentric actions: good for mobility and simultaneous stability, good for start strength
Disadvantages of quasi-isometric eccentric actions: not very good for hypertrophy or maximum force
Benefits of partial actions: better for hypertrophy, strength and variety, exclusively stimulates the connective tissue and the CNS in a way that full-range light movements can not
Disadvantages of partial actions: specific to the range; does not transfer well to other regions of the movement, not optimal for hypertrophy
This is because I believe that a combination of repetition exercises and speeds should be performed for hypertrophy and the sporting lifters look for. One cannot receive optimal development simply from a single method. Certain exercises lend themselves more to explosive repetitions while certain movements lend themselves more to controlled repetitions. One should have a variety in self-training regarding the selection of exercise as well as the types of repetitions to strengthen all ranges of movement to the maximum, if one's goal is to develop the largest muscles possible or the most powerful as possible.
