TIPS ON LOWER BACK PAIN AND HAMSTRING STRETCHES
Many cyclists struggle with lower back pain when cycling. This can be due to incorrect bike setup or size. Tight Hamstrings or weak lower back stabilisers relative to Hamstring strength can also be the reason: see http://physioactive.co.za/lower-back-pain-cycling/ . A good physiotherapist will be able to establish if that is the case.
The treatment might include hands-on joint mobilisations and myofascial release. Most important in the long term will be to correct the imbalance between the Hamstrings and the lower back muscles.
People often stretch their Hamstrings incorrectly. An old fashioned round-your-back-to-touch-your-toes type stretch will do nothing to improve the imbalance, and will probably even make the imbalance worse, as it flexes and thus lengthens the already weak lower back muscles.
One has to learn to activate the deep lower back stabilisers (http://www.thansworld.com/ONLINEanatomy_1/pages/section5/oi_multifidus.htm) (http://brentbrookbush.com/multifidus/) and maintain neutral spine when lengthening the Hamstrings. Your physio should know a variety of methods to re-educate your lower back stabilisers. Stretching your Hamstrings correctly will make it easier to maintain a closer to optimal lower back posture on your bike.
If your Hamstrings are too tight or your back muscles are too weak, or if you are just unaware of a good posture on your bike, you might slowly sink into a more flexed (rounded) lower back position on your bike as you get tired. What one has to bear in mind is that bike set-ups often get done when one is fresh and cold. One’s posture often changes as one fatigues and that causes the hip, lower back, shoulder and neck angles to change. An awareness of this, as well as strengthening of the muscles that need endurance to avoid this, will ensure that you can self-correct when you catch yourself slowly sinking back into an over rounded lower back position.
To give your back a break on your bike e.g. on a gentle downhill, you can roll your pelvis to do lumbar flexion and extension movements. This will allow your back muscles to relax. It also helps to think of lengthening your whole spine from the sacrum upward to lessen the give/sink into flexion while you cycle.
With your feet in cleats, you use your Hamstrings a lot and Hamstrings can increase in tone during a cycle. On a gentle safe downhill, you can stretch your Hamstrings by lifting slightly out of your seat and slightly hollowing your back/tilting your pelvis – you should be able to feel a lovely lengthening of the Hamstrings of the straighter leg (i.e. the leg in the cleat that is in front) if your Hamstrings are over toned. Be careful to not flex your foot up at the same time. If you have increased neural tension, this can potentially irritate the nerves. It is safer to do this stretch with your foot relaxed or gently pointed.