Hamstring Injuries

Introduction

The dreaded hamstring strain is without doubt one of the most frequent and most difficult sports injuries to manage.  If you’ve been running for long, there’s a good chance that you’ve visited one of the following scenarios at some point in your career.  The first is when you notice that slight niggle or tightness in the back of the thigh that you pass off as one of the ordinary day to day aches and pains that go together with distance training.  Only it doesn’t go away but becomes more noticeable with each step, until training is no longer possible at more than a Cliff Young shuffle pace.  The second is when you step up your speed in an interval session or the beginning of a race, and experience the acute searing pain in the posterior thigh that makes you think the runner behind you has stabbed you in the leg with a pen!
 
Whether it’s the first or second scenario that causes you to break into a cold sweat, the chances are that a couple of frustrating months lay ahead of you.  Frequently, there is an extended period of tightness, pain, and fear of re-injury, which unfortunately is commonplace.  So, lets examine the nature of the injury, the likely causes, and most importantly, how to avoid the dreaded hammy strain.
 
Anatomy/Pathomechanics
 
The hamstrings muscle group is made up of the biceps femoris (outside of the leg), semimembranosus (inside), and semitendinosis (inside) muscles, which act primarily as extensors of the hip and flexors of the knee.  Sometimes, one of the adductor (groin) muscles is included in this group due to its functional similarities.

During running, the hamstrings are most active at 3 stages:

1. as the leg swings through to decelerate and control hip flexion and knee extension
2. to prepare the foot to hit the ground and to stabilise the knee as foot contact is made
3. to extend the hip and flex the knee at the end of the stance phase to propel the body forward

Problems usually occur at the end of the swing phase, as the hams contract to control the hip and knee and get ready for landing, or at the end of the stance phase as they contract forcefully to push the body forwards.
 
Causes
 
To state that the cause of posterior thigh pain can be a complicated issue is an understatement.  Let me explain.  While we usually think pain in the back of the thigh is hamstring-related, symptoms can be caused by a number of structures.  Some of the potential culprits include:

1. Hamstring muscle strain
2. Hamstring tendinopathy – tendonitis, degeneration, partial tears
3. Bursitis
4. Sciatic nerve entrapment, which frequently accompanies muscle and tendon injuries as the nerve adheres to scar tissue
5. Lumbar spine pathology such as disc lesions
6. Sacroiliac joint pain syndromes

Quite often, it’s a combination of these pathologies that result in tightness and pain in the hammy, dragging out the rehabilitation process.  For example, addressing the muscle-tendon issue without addressing the nerve tension issue will only slow you down and result in more frustration.  Likewise, if you’re stretching the crap out of your hammy, but the problem is coming from your low back, you’re not likely to get very far.  For this reason, a thorough assessment by a sports medicine professional is critical.
 
Assuming the cause of your depression is the classic hamstring muscle strain, that doesn’t necessarily make it an easy fix.  Often, it’s impossible to point to a single reason for your hammy strain, because the problem is almost always multifactorial.  There are a few factors that have been looked at extensively, and a few that are no more than proposals, but it is likely that some combination of the following is to blame:

1. Decreased hamstring strength
2. Decreased flexibility – this could be of the hamstrings themselves, the quads (forcing the hams to work harder), or the hip flexors
3. Inadequate warm-up
4. Fatigue
5. Muscle imbalance – quite often in the gym, the hammies are neglected for their more aesthetically pleasing counterparts, the quads
6. Pelvic asymmetry – if a pelvic bone is rotated forwards, this means the hamstrings are already on stretch before you start running…not a great scenario!
7. Poor neuromuscular control – the ability of the hamstrings to contract and relax in a coordinated way at the right time is critical to their success.  If the activity is novel, such as your first speed session for 6 months, or you’re particularly tired for example, there’s an increased risk of hamstring strain
8. Overstriding when running
   
   

SOAP BOX:

If it’s more than a niggle, or it’s been slowing you down for a while now, get it looked at!