In this section you will see the Science/Concepts/Overview of certain Lifts/Pulls related to Vertical Power:
- Olympic Lifts/Pulls: Clean Pull Mid Thigh/Below Knee/Floor & Snatch Pull Mid Thigh/Below Knee/Floor
- Olympic Lifts/Pulls with Variable Load: Deadlift/Clean Pull with Band Resistance
could you explain me, what is it the stretch reflex?
Stretch reflex is muscle contraction in response to stretch of the same muscle in a very short period of time. Think of muscle as rubber band (a very rough simplification, but a good analogy nonetheless). When a rubber band is stretched, its elasticity provides a contraction force to resist the stretch and return to its relaxed length. Usually the harder and faster a rubber band is stretched, the stronger its contraction force. This analogy generally applies to muscle as well during stretch reflex, in that when a muscle is stretched in a very short period of time, it automatically generates a contraction force to counteract the stretching force, without a person’s voluntary control.
The detailed mechanism of muscle stretch reflex is more complicated than the rubber band analogy. But in simple terms, there are two components in muscle stretch reflex. One of them is almost the same as the rubber band analogy, in which the innate elasticity of muscle fiber and tendon allows them to serve as human rubber band (here comes the importance of maintaining muscle stiffness, i.e. increasing the threshold of elastic energy of muscle and tendon, in training). The other concerns muscle spindle, which is located inside muscle fibers that can sense the rate of muscle fiber stretch and send signals, without passing through the brain, to contract the stretched muscle (and also relaxes the antagonistic muscle).
The purpose of muscle stretch reflex, in pure physiological terms, is most likely to prevent over-stretch of a muscle. By initiating contraction right after a stretch, the extent of muscle stretch can be mitigated, thus protecting the integrity of muscle fiber. On the other hand, human movement takes advantage of muscle stretch reflex to generate much more power than one can voluntarily achieve. E.g. a pause squat is harder than a non-pause squat; a touch-and-go bench is easier than a pause bench; and a standing vertical jump is lower than a moving-start vertical jump.
Best regards,