Relaxin is a reproductive hormone that was originally identified in 1926 as a hormone that causes relaxation of the pubic ligaments. Subsequent studies have identified several functions of the hormone, some of which are important to massage therapy. Therapists trained in pregnancy massage understand that deep tissue techniques are contraindicated. Meaning that lighter techniques need to be used during pregnancy due to the presence of relaxin. However, relaxin is not just a pregnancy hormone and impacts our lives in other ways.
What does Relaxin do?
It does exactly as the name implies, relaxin relaxes soft tissue. Like many hormones, relaxin levels change depending on its purpose. For women, relaxin is present during the menstrual cycle, pregnancy, and perimenopause. For men, it also has a role in reproduction!
Menstrual Cycle
During ovulation, relaxin is produced to aid progesterone to help implant a fertilised egg. If fertilisation occurs more relaxin is produced with the increase in progesterone. Relaxin and progesterone levels will reduce when there is no conception.
Recent studies have linked increased anterior cruciate ligament (ACL) injuries in women athletes to the raised levels of relaxin. These studies have shown that these injuries are more common during ovulation. Many sports sites are now saying that women should be tracking their menstrual cycle to understand its impact on performance and risk of injury. This increase in risk does not apply to women on certain types of birth control where ovulation has been suppressed.
So, currently there is no good advice about protecting your ACL in sport during the latter half of menstrual cycle. Certainly, if you play a high impact sport such as football, hockey, or netball, you need to be aware of the risk of injury due to your relaxin levels. Sports coaches and personal trainers should also understand and advise about the risks associated with raised relaxin levels.
Healthy pregnancy
Pregnancy
While relaxin is produced during pregnancy, it is not constant and fluctuates at different stages. During the first trimester, relaxin helps the embryo’s implantation and may help the formation of the placenta. Massage is contraindicated during the first trimester, but this is for other reasons not related to relaxin.
Relaxin has a huge role in preparing the body for childbirth. Its role is to relax the ligaments in the pelvis and to soften and widen the cervix to facilitate delivery. While relaxin relaxes soft tissue, massage still has an important role in reducing the stress, aches and pains experienced by the expectant mum. More information can be found on the National Childbirth Website: https://www.nct.org.uk/pregnancy/how-you-might-be-feeling/pregnancy-hormones-progesterone-oestrogen-and-mood-swings
Menopause
The menopause is characterised by a reduction in the body’s reproductive hormones. It is known that reproductive hormones protect women from cardio-vascular disease (CVD). Which explains why instances of CVD increase post-menopause. Research has identified that the presence of relaxin is a contributor to this protection.
Men also produce Relaxin!
Relaxin is also found in the semen plasma of many species and is produced in the prostate gland. Its presence can improve the chances of successful fertilisation by increasing sperm penetration.
More Research needed
It’s only in recent years that the wider impact of relaxin has been a subject of research. Most of the data available comes from research on mice, rats, and monkeys. While more studies on humans are still needed. Our knowledge has grown from understanding the importance of this hormone in human reproduction to trying to understand its impact on modern life though activity or menopause.
The popularity of women’s sport, training and activity have become more popular than ever. Society has woken up to the fact that an active lifestyle is essential to living a healthy lifestyle. Therefore, it’s only right that the knowledge for safe participation and an understanding of the risks are readily available for all.
There is a huge potential from research into this hormone that will benefit infertility, heart disease, menopause, sports injuries, and many other unknown health issues. As for massage, the more therapists understand the impact of hormones like relaxin, the more we can deliver positive and effective therapeutic outcomes.
