Slowing down the lowering phase of weightlifting increases muscle damage and protein synthesis, while speeding up the lifting phase improves power output, meaning changing the speed of movements can...
Mechanism
Synthesis from 1 study
Slowing down the lowering part of a lift stretches your muscles longer, causing small tears that signal your body to build more muscle protein. Speeding up the lifting part makes your nerves fire faster, activating more muscle fibers at once to produce explosive power. So changing how fast you move...
Most probable mechanism
When you lower a weight slowly, your muscle fibers stretch under tension for longer, which pulls on the muscle structure and causes tiny tears. This triggers the muscle to rebuild itself stronger and bigger by making more proteins. When you lift the weight quickly, your nerves fire faster and more muscles activate at once, helping you generate more power and speed. So slowing down the lowering part builds muscle, and speeding up the lifting part makes you stronger and more explosive.
Prolonged eccentric contraction increases mechanical tension on sarcomeres and extracellular matrix structures, inducing microtears in muscle fibers and disrupting cytoskeletal integrity
Mechanical tension activates integrin-based and stretch-sensitive signaling pathways, including FAK and mTOR, which upregulate mRNA translation and increase muscle protein synthesis
Sustained muscle contraction during slow eccentric phases accumulates metabolic byproducts such as hydrogen ions and lactate, activating group III/IV sensory afferents that enhance spinal reflex excitability and motor unit recruitment
Fast concentric contraction recruits high-threshold motor units rapidly due to increased rate of force development and reduced inhibitory feedback, enhancing neuromuscular efficiency and peak power output
Net protein accretion occurs over time following repeated bouts of prolonged eccentric loading, leading to structural repair and regional hypertrophy, while repeated fast concentric actions improve neural drive and synchronization of motor units
Evidence from Studies
Supporting (1)
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