T Nation

Relaxin and Stretching


When attending birth classes with my sister, I heard that pregnant women release a hormone called relaxin which allows for greater flexibility which is required during childbirth. It is also mentioned that pregnant women should be especially careful while stretching as it is more possible to get muscle tears and injuries.

Now, as someone who does martial arts which requires a great level of flexibility, my mind naturally ticked over. Could relaxin be just the hormone to help facilitate more rapid gains in flexibility?

I asked the doctor in the family, and she said that it wasnt a great idea (because of above mentioned danger of overstretching). However, I think, that perhaps carefully administered, it would be a good way to help with sticky areas, such as my groin, which seems to lag WAY behind the rest of my body in flexibility.

Could this perhaps be the new 'steroids' for flexibility?


Relaxin is a double edged sword, in that it does indeed permit greater flexibility in muscles but also all soft tissues, e.g. ligaments, tendons, arteries, veins, GI tract etc. These organs may not benefit from being extra flexible! (unless you are indeed pregnant)

Ligaments are relatively non - elastic and if over stretched will not return to their original length which may result in joint instability and joint pain...Sacro-illiac joint pain is often attributed to this.

So, all this increased flexibility may well come at a cost.

Now if someone can develop site specific relaxin they may be on to a winner!



Yeah, site specific relaxin injections, taken for short periods of time (no more than 3 months?)...

I've been asking my sister about this for a while, and i did get her to admit that there could be a way to make it beneficial.

Could be really good for muscles that have tightened up due to injury?

In my case, i think the root of it is a tight lower back... can touch my palms to the ground and then some, so hamstrings are fine, but something stops proper pelvic tilt from occuring to allow for great sideways leg flexibility.

I'd love to see something like this developed to help my on my quest.


Shrug, until then, I guess i need to just stretch more religiously... 2 times a day on most days: calves, hips flexors, back, various hamstrings, groin, deep hip, glutes, quadriceps... focus on the weak points, use PNF more etc etc....