Your hamstrings are connected to your knees and your pelvis, and their job is to flex the knee as well extend the leg from the hip.
When your body is well aligned, your bones are stacked with a slight curved spine. This protects joints and ligaments and makes the muscles work most efficiently without strain. If the hamstrings are tight they will pull down on the pelvis, which then straightens out the lower back, as well as pulling the knees back.
The first figure shows an ideal posture and the second one shows what it looks like when your hamstrings starts pulling on the bones.
The strain put on your lower back when it is constantly straight weakens and exhaust the muscles around the spine, causing pain and discomfort. As you can see in the illustration, the neck also starts arching more and the chest gets slightly compressed which can make it harder to breath properly, meaning that you are not getting enough oxygen.
Are your hamstrings tight
An easy way to see if you have tight hamstrings are to lie down on floor, keeping both your legs straight as you start lifting one up towards the ceiling with the other one flat on the floor. If the angle between your legs are 70% or less, they are considered tight with 90% being ideal.
Tight hamstrings in yoga
Stretching your hamstrings can sometimes be a little bit tricky, and it is important to be careful. Lower back strains are the most common injury in yoga. Luckily it is easily avoidable with some general knowledge.
Like we said earlier, the hamstring is connected to the pelvis, and if the hamstrings are short they start pulling the pelvis down.
The way to avoid this is to try and keep your spine as straight as you can when you fold, this is why we do “flat back” or “half lift”, this will help the fold come from your hips. Tensing your quads, front of thighs, will also help drawing your hips towards your legs. When you can’t go any further with your spine straight, symmetrically allow your spine to round slightly.
This will more efficiently stretch your hamstrings as well as protect your spine.