Bare with me, because I believe the following to be relevent to ze question;
Russian weightlifting great; Vasiley Alexeyev, is the one that most impressed the Russian coaches in the famous 1960’s test, where athletes from different sports took part. They were suprised by how fast Vasiley Alexeyev was over 20 meters. My point is that although he was not as fast as olympic sprinters from 30meters on, he was faster than the other weighlifters. Could the following factor be a part of the reason?
Vasiley alexeyev did 1000 knee lifts in waist deep water, every morning. He considered it as work capacity training. (But consider that it must have greatly strengthened his psoas major muscles).
Could that be the reason he was faster over the 20 meter sprints than practically al other eigtlifters, or was it only because his rate of force development in posterior chain was higher. (after all, he was pretty mean in the snatch lift and clean and jerk.) But then so were a lot of the other weightlifters. But none of the other weightlifters did 1000 knee lifts per day as their morning work out.
Now, i’m not pretending Vasiley alexeyev could hold a candle to an olympic sprinter when it came to max v. For starters, he looked anything but a sprinter, his gut was massive.
What would be the best way (and more practical) of developing the psoas? Could anything possibly beat sprints at developing psoas? If so, then I’d add such an exercise to the program. So long as it doesn’t come with the problems that sit ups do, such as low back pain in the middle of the set.
Now “Rj24” has suggested decline sit ups. he sais ‘heavy’ but I’m not sure that ‘heavy’ is the way to go with the psoas?
The following exercises will develop psoas muscles and other hip flexor muscles.
Step-ups.
Tendon compliance and be developed with ballistic stretching.
Tendon stiffness