As far back as I can remember, Hamstring flexibility was seen as the coolest and most important tests of physical mobility. If you wanted a test of strength there were plenty to choose from, push ups, pull ups and even arm wrestling but as far as mobility went, being able to touch your toes was the Gold standard!

Most of us boys grew up practicing high kicks and roundhouses after watching Bruce Lee movies and then followed up in martial arts training while the girls were doing the same in ballet class though with rather more poise and control. Even in gym class it seemed a necessary pre-requisite to warm up by touching your toes before being allowed to play sports.

There was always someone in the class who would love showing off by putting both palms firmly on the floor while the rest of us had to cheat by bending our knees and hoping no one noticed. But as most of us were deemed acceptably flexible (even if we cheated a little) there was always one boy who couldn’t hide the fact that he was seemingly made of wood. There was nowhere to hide for this poor soul who came into so much scrutiny and ridicule that I remember practicing hamstring flexibility religiously lest I be crowned the class Pinocchio.

Fear of failing this test of physical prowess seems to be so deeply lodged in the subconscious that it transcends cultural boundaries and wherever we are teaching in the world we always get asked the same question: “I’m stretching every day, why are my hamstrings still so tight”?

1. Poor Stretching Technique

If you’re not getting the gains you expect when stretching the hamstrings then take the load off them. Muscles don’t like eccentric loading or lengthening while contracting, it’s super confusing for them when your primary goal is flexibility. Also make sure you work on opening up the insertion points behind the knee where the hamstrings are tightest from long hours of sitting with your knees bent.

The Image below shows how to use a rope to open up the hamstrings. The subject is pulling the leg into hip flexion while gently pulling on a rope. Hold at end range for 2 seconds and then repeat 8-10 times.

2. Not working the oblique fibres

The hamstrings are comprised of 3 muscles which have multiple functions including rotation of the tibia and fibula bones below the knee. In order to do this the hamstrings have oblique fibres that enable changes of direction when we play sports. If you want to have super mobility then opening up these fibres with the following exercises will have you twisting and turning like an NBA all star !

The image below shows how to target the lateral hamstrings or the biceps femoris. He is using the rope to pull the ankle towards the opposite shoulder while the leg is externally rotated about 45 degrees.

3. Poor hip flexor strength

Muscles work in relationships and the best way to improve hip flexion is by getting stronger at hip flexion. Contracting the hip flexors by lifting the leg towards the ceiling forces the opposing muscles which in this action would be the hamstrings to relax and open up.

This process is called reciprocal inhibition and is the underlying principle in the Active Isolated Stretching protocol we use at the clinic.

4. Poor hamstring strength

Hamstring strength is a crucial and often overlooked factor in hamstring mobility. Generally speaking tissue will only open so far as it has the strength to pull back to neutral. This means the that body won’t let you move into a position that it is not confident in getting out of.

Also, flexibility is controlled by the brain and the nervous system and not the muscle as so many of us are taught. When we relax the nervous system with repetition and build confidence by moving regularly or getting fitter, the nervous system relaxes enabling greater agility. This is why we recommend a flossing or oscillatory technique rather than static stretching.

Range of motion of active knee flexion
Range of motion of assisted mobility

Here we can see the difference in range of motion between an active knee flexion using only the strength of the hamstrings and assisted mobility which is very important for optimum performance.

Try this at home and remember to keep the core tight and pelvis still during the movement. It’s harder than it looks but the benefits of strengthening the hamstrings to full range are very important for athletes.

5. Poor pelvic alignment

The hip flexors allow up to 90 degrees of hip flexion before the pelvis becomes involved by rotating backwards to enable a greater range of motion. If your pelvis is locked in anterior rotation then you may find it difficult to overcome the 90 degree barrier. The pelvis is made up of 2 bones called iliums and if they don’t meet perfectly at the groin or pubic symphysis then you will also find hip flexion and hamstring mobility an issue.

If this is the case for you then seek out a good manual therapist and get some good realignment. Do ensure that you get some good advice and even exercises you can do at home to keep your pelvis balanced. The last thing you need after a good therapy session is to undo all the good work by sitting with your legs crossed.


Thank you for reading! We really hope this article was useful though we only covered 5 of the most common reasons why hamstrings remain tight even after weeks of diligent stretching. For a more personalised approach please do contact us at or come in for an assessment. Best wishes and keep inspired with your mobility drills from all of us at The Stretch Clinic.

Written by Liam Harkness,
Chief Therapist
The Stretch Clinic