There is a persistent belief among the public, many personal trainers, some coaches, and even a few exercise scientists, that weight training exercises must be done slowly. The intentional use of slow movement in weight training reflects an inadequate understanding of the nature of efficient power production, the physics of work, and weight-room safety.
A slow cadence increases the "time under tension: (how long the muscle spends in contraction) and is thereby thought to increase the amount of work the muscles do and the resulting amount of muscular development. An examination of the physiology of power production is necessary to understand this.
Power is strength displayed quickly, the ability to explode against a resistance. High power production depends on the rapid recruitment of a maximum number of motor units to generate the high amount of force necessary to produce that power. More power requires an increased efficiency in the recruitment of high numbers of motor units and the quickness with which they come into contraction together.
Most importantly for the person interested in more muscle, high numbers of motor units working at the same time means an increase in the actual amount of muscle tissue involved in the work. As more "high-threshold" motor units -- the ones that get recruited only by the highest level of stimulus, to produce the highest amount of force -- are recruited to generate more power through increased work production, more of the muscle fibers in the muscle go to work.
This uses more ATP that must be replaced through active metabolic processes. Studies have found that longer duration repetitions with a longer time under tension actually demand less metabolic work when compared to fast-moving repetitions powered by higher numbers of motor units firing together. This is because in slow movements only the lower-threshold motor units are recruited and fatigued by lower-movement-speed exercise.
It is true that motor unit fatigue produced during sustained contractions or with higher repetitions (8-12 or greater) produces a "burn," a sensation that is perceived by many personal trainers to be an indicator of high-quality stimulation. But the fact is that more motor units and more total muscle mass is recruited and worked by higher-velocity movement than by slow exercise speeds.
In the interests of both muscle mass and power training, higher velocity works better.
The commercial emphasis on exercise with machines may be the source of a lot of the misinformation about weight training, due to considerations other than the physiology of exercise. Because of their construction, exercise machines generally have limitations in their use, one of which is that if the stack is dropped, the plates may fracture. Over the decades since the invention of Universal and Nautilus machines, this limitation has resulted in the dogma that a slow exercise cadence (a count of 2 up and 4 down or something similar) is needed for optimal results from weight training. This also controls the noise level in the spa. It is merely good fitness club management, not effective strength training. The conventional wisdom has actually developed from the desire of club management to extend the life of their machines and make for a more placid business environment.
Note: I used to watch videos of the the extreme super slow type of resistance training that got a lot of sales-traction some time ago. It always reminded me of a sick dog eating its own shite and I enjoyed it immensely before taking a short nap in the afternoon. When I'd wake up, the blank-faced guy would still be doing super-slow reps on some machine deal there in the video. But then, when younger I used to video freeze-frame Peter North with his O-face on and head out the door to go to work. Safety also gets dragged into discussions of movement velocity, under the assumption that fast is dangerous, as in driving a car. "Speed kills," after all.
But just as in driving, it really depends on the ability of the operator.
The more experienced an athlete becomes with barbell exercises, the more efficiently and safely he can perform them at higher speeds. Squats can be dangerous for novices at high speeds, but for advanced athletes high-speed squats are a very productive power exercise. If technique is correct, all multi-joint exercises can be performed in a way that enhances power production. Safety is the result of CORRECT TECHNIQUE, at any velocity.
High-speed exercise is necessary if power is to be trained. This obviously means that power training is not inherently dangerous; if it were, all power-trained athletes would be injured.
Bad technique is inherently dangerous, whatever the speed or load.
Good technique increases safety, and that should be the goal in any weight room.
The correct velocity of an exercise should be determined by the movement pattern of the exercise and the effect the exercise is intended to produce, not by arbitrary notions of intensity or safety. The Olympic lifts and their variations cannot be performed slowly. A slow clean is not a clean; in fact, a clean CANNOT be performed without an acceleration through the middle of the pull that produces sufficient momentum in the load that continues upward long enough to shift the feet to catch the bar.
On the other hand, some single-joint exercises cannot be performed both quickly and correctly. A strict barbell curl cannot be performed rapidly through the entire range of motion. In fact one might argue that the more slowly an exercise must be executed, the less valuable it is for sports training.
This is true for any exercise, regardless of its nature -- a heavy snatch comes off the floor more slowly than a light one, although it will still have to be accelerated if it is to be racked at the top. Movements that are limited by absolute strength will approach zero velocity in a true 1RM, and will always be slower than a 1RM explosive movement.
Many factors affect movement speed, and blanket statements about what is best are seldom useful --
except for this one:
For exercises useful to strength training for a sports application,
FASTER IS ALWAYS BETTER.
Enjoy Your Lifting!
June 7, 2025. 104 minutes. A portrait of Queensland's Joh Bjelke-Peterson whose controversial rule (1968-1987) saw growth and corruption. Through archives and interviews, it reveals parallels with Trump's era and style.
June 10, 2025. 512 pages. C.M. Kushins tells Leonard's full life story against recurring themes and evolving storytelling methods of his work, drawing on interviews with primary sources ranging from Leonard's family and friends to those who acted in, produced, and directed his work onscreen. He also includes never-before-published excerpts from Leonard's unfinished final novel and planned memoir.
Definitive and revealing, "Cooler Than Cool" shows Leonard emerging as one of the last writers of the pulp fiction era of midcentury America, to ultimately become one of the most successful storytellers of the twentieth century, whose influence continues to have far-reaching effects on both contemporary crime fiction and American filmmaking.
2011. 138 pages.
No comments:
Post a Comment