Slow Eccentric
Slow Eccentric innervate more of the Type I Slow Twitch Muscle Fiber.
Fast Eccentric
Research show that for increasing strength the Eccentric Movement elicits the greatest effect when it is lowered in around 1 second. This Eccentric Speed Innervates the Fast Twitch Muscle Fiber.
1) It allows you to use a greater training load in the movement.
2) Force = Mass X Acceleration
Due to the increase speed in lower the weight, the bar load or in this case the Kettlebell load is magnified beyond it true weight.
Bench Press More, Now
Dr Tom McLaughlin
This book graphically illustrates how the Eccentric Speed of the bar magnifies the it's true load.
Novice Lifters
Novice Lifter lowered their Bench Presses quickly.
McLaughlin determined the bar weight was magnified 149% beyond it true weight.
If they used 300 lbs, that load was magnified to 447 lbs in lower its too fast.
Elite Lifter
Elite Lifter lowered the bar much slower.
McLaughlin determined the bar weight was magnified 112% beyond its true weight.
If they used 300 lbs, that load was magnified to 336 lbs in lower it too fast.
The Take Home Message
It easier to drive 336 lbs off you chest in the Bench Press than 447 lbs.
Using Eccentric Speed For Overloading
While Eccentric Speed is detrimental for Max Strength Movement, it is and effective method in other areas; such as increasing Maximum Strength in traditional movements, as noted below.
Moderate to High Speed Eccentric Only Training
Short-term high- vs. low-velocity isokinetic lengthening training results in greater hypertrophy of the elbow flexors in young men https://www.physiology.org/doi/pdf/10.1152/japplphysiol.01027.2004 ...higher velocity (3.66 rad/s) isokinetic lengthening contractions are associated with greater...
www.strongfirst.com
Short-term high- vs. low-velocity isokinetic lengthening training results in greater hypertrophy of the elbow flexors in young men
https://www.physiology.org/doi/pdf/10.1152/japplphysiol.01027.2004
..
.higher velocity (3.66 rad/s) isokinetic
lengthening contractions are associated with
greater muscular hypertrophy than slower (0.35 rad/s)
velocity lengthening contractions.
We observed, despite a >10-fold lower mean torque-time integral (Fig. 6), a
greater degree of hypertrophy (Fig. 3) with a
training protocol that involved only high velocity lengthening contractions.
Fiber type-specific changes after eccentric training
https://www.patreon.com/posts/fiber-type-after-28196633
Not every type of eccentric training causes preferential increases in type II muscle fiber area, and some types actually cause type I muscle fiber area to increase more!
#2. Preferential type I muscle fiber hypertrophy
...when
slow eccentric phases are used during normal strength training, this
causes increased type I muscle fiber size, ...
Slowing down an eccentric does not enhancement or recruitment so
it is not "eccentric overload".
It only increases time under tension.
Research shows the
slow negatives do not elicit the most effective response.
Slow Eccentrics For Growth?
Slow eccentrics for growth? - Dan Ogborn
Dan Osborne found that with eccentrics/negatives is...
1) "...
greater following high rather than slow velocity eccentric actions (29)."
2) "...as far as
strength was concerned,
fast eccentric actions were superior."
3) "...
growth of type IIa and IIx fibres was greater with fast eccentric actions."
Negatives: You're Doing Them Wrong
https://www.t-nation.com/training/ne...ing-them-wrong
As per Chris Thibaudeau...
1) ..."going slower will not improve the stimulatory affect of the eccentric. ...it
won't recruit and stimulate more fast-twitch fibers."
2) "The Essential Points: Focus on heavy and controlled, not on moderate weights lowered slowly."