If the ancient sage Patanjali practiced modern postural yoga, I think he certainly would not advocate for many of the approaches to stretching the hamstrings we see in gyms and yoga studios around today.
For years when students come to yoga class the same questions are asked to yoga teachers. ‘How can I improve my hamstring flexibility in forward bends?’ Or ‘my hamstrings are too tight, can I still do yoga?’
The approach in the past has often been just ‘keep stretching those hamstrings! They’ll come around eventually! Just do more stretches, do more yoga poses! While this approach may help a little, for the most part it doesn’t really work. To understand why, we need to look at the reasons why hamstrings are ‘tight’ in the first place and also what does the word ‘tight’ actually mean?
When you feel tension in your hamstrings and are unable to touch the floor in forward bends does that mean your hamstrings are actually physically shortened? This has been the dominant paradigm of most yoga practitioners and those in the health sciences & fitness industry in the past. It then follows that one must stretch the hamstrings rigorously to increase their length. This idea has led to injury in many practitioners over time as eventually the constant pull of ‘tight’ hamstrings tugging on their attachments leads to ‘wear and tear’ of adjacent structures. Commonly this mechanism will manifest as hamstring tendon injuries, sacro-iliac joint, knee and/or lower back injuries.
More recent research into biomechanics and muscle physiology has shifted this perspective to a more updated theory that suggests our flexibility is actually governed by our brain and central nervous system via alterations in our sensation. This theory is referred to as ‘sensory theory’
As the research article describes this theory suggests that the change in extensibility of hamstrings that occurs after stretching is due to changes in the perception by our brain about the degree to which our muscles are being stretched and any perceived threat to adjacent structures. So our tightness or inflexibility is not so much due to our muscles being too short but due to our brain trying to limit our movement or stretch of the muscle to stop us from going too far and causing damage.
Our brain is always trying to protect us from tissue damage and harm. If we are taking it too far in a forward bend and ‘overstretching’ it may not be because our hamstrings aren’t long enough but because our brain perceives a threat to some structures if we were to keep going. This may or may not be the hamstrings muscles themselves but could be the hamstring tendons, the sacroiliac joint or lumbar spine joints above, or the knee joint below. If the hamstrings were to keep stretching the brain is detecting from its various sensory inputs that there is potential compromise to the integrity of one of these surrounding structures. It subsequently sends the message that the hamstrings are ‘taught’ and are at their maximum length, so they stiffen.
So if this is the case then one potential way we might be able to increase the extensibility of our hamstrings in a forward bend is to ensure that we are recruiting our muscles in the correct patterns and stabilising adjacent structures effectively. An example of this would be activation of the gluteal muscles when coming into the forward bend and further re-engagement when deep in the forward bend.
When your yoga teacher cues to ‘pull your mat apart or to shift your weight into the balls of your feet’ to activate your outer hip muscles’ he/she is calling to your glutes to switch on and stabilise your pelvis as you move deeper into the fwd bend. If you practice in this way you may notice this cue gives you a little more depth in the pose. It’s as if your hamstrings magically got a little ‘longer’.
When the correct muscles are activated in the optimal patterns the brain detects there is less threat to the adjacent structures. The brain says: ‘ok hamstrings you can go a little further cos the glutes have got the sacroiliac joints covered and everything’s looking stable up there’
This is just one example of how this mechanism works but like with anything to do with the human body its multifaceted. One of our primary goals in yoga classes is to cultivate balance in the body. When posture is optimally aligned, the body stays agile without the need to do intense stretches to relieve tension in the hamstrings.
The best way to improve hamstring flexibility safely and get the most out of your practice on the mat is to get an individual assessment from a physiotherapist with expert knowledge in biomechanics and movement dysfunctions. Cathy Aganoff is an experienced physiotherapist and yoga and pilates instructor. She provides posture and movement analysis consultations and prescribes yoga therapy and clinical pilates programs to help you optimise your movement patterns and performance both on the mat and off the mat in everyday life. You can contact her for an appointment at tribalance studio in Brisbane.