As mentioned, this factor gets quoted all over the place re isometrics, but when you look for the research that backs it up you find that it isn't nearly as well-supported as you might think - it appears to be very conditional based on joint angle selection.
There is research as well as anecdotal data that has demonstrated that
"Strength increases over a range of 15 to 20 degrees
on either side of the training angle".
That is why this method has been advocated by and employed by Strength Coaches: Bill Starr, Chris Thibaudeau, Charles Poliquin. Josh Bryan and others.
As TheWolf noted, "
The ability to target specific joint angles makes isometrics a perfect choice to overcome sticking points in dynamic movements."
This is one the greatest benefits of Isometric Strength Training in the Stick Point area.
Functional Isometrics
Several previous post have presented information on this, as means of increasing strength in the Stick Point area.
Training Examples
The common sticking point for a Conventional Deadlifter is in the knee area.
Thus, Conventional Powerlifter often perform Rack Deadlifts in the range specific knee area in a Power Rack.
Anna Halting Deadlifts (Post 130)
The deadlift is definitely a lift that took me a while to learn how to do correctly. And I say correctly because I have done them safe since the beginning, but it took me time to learn how to get really tight and engage the correct muscles during the setup to build tension before starting the...
www.strongfirst.com
"Yesterday I pulled 300x5 (a long time goal!) and it moved so much faster off the floor.
I've been doing the Halting deadlift just as demonstrated in your point 4 above from the Mark Rippetoe video, to just above the knee and keeping the shoulders out over the bar. 3x8, as he recommends. 1/14 I did 185x8x3, 1/25 I did 205x8x3, aand 2/11 I did 215x8x3. Each time it felt like a lot of work specifically targeted for that weak point, but not a lot of "deadlift heavy" work that required a lot of recovery.
Halting Deadlifts as with specific range Isometric, targeted her Sticking Point.
Performing Rack Pulls would not have increased her strength in breaking the weight off the floor.
The same is true in performing Isometric Action from let's say the top end part of any movement.
Practical Experience
Years ago, Hollie Evette (National Powerlifting Champion and Strength Coach) introduced me to Isometrics and Functional Isometrics.
He devised an Isometric Training Program for my Bench Press performed from multiple angles, with an emphasis on the Sticking Point.
I followed plan but was skeptical. However, at the Powerlifting Meet, I posted a Personal Bench Press Record.
I continue to employ Sticking Point Isometrics and Functional Isometrics in my training.
I have also worked with other lifter with strengthening their Sticking Point Training; in that specific range.
Take Home Message
1) The Law of Specificity
This definitely applies to increasing strength in a lifter Sticking Point.
As the saying goes, "Your only as strong as you weakest link".
2) Anecdotal Data
If focusing on the development of strength in the Sticking Point area wasn't effective, it would not have been advocated by some of the best Strength Coaches in the field: Starr, Thibaueau, Poliquin, Bryant and others.
Essentially, with Strength Coaches, as with all vocation, "Produce or Perish" applies.
If a Strength Coach can't produce result, they are gone.
That applies to all vocations.