A classic injury but one often not diagnosed well or treated properly and thus has a reputation for recurrence. The symptoms are a sharp pain or a rapid build-up of pain somewhere in the belly of the hamstring. It is often in the middle of the muscle but it can be higher towards the buttock or down to the knee and the stringy tendons.
Gradual build-up type of ache or tightness is less likely to be a full tear but micro tears in the tissue which combine over time to make a significant injury.
It is often associated with lower back and pelvis issues and the nerve irritation and/or inhibition caused by the back affects the hamstring, increasing the likelihood of injury. You should have the back assessed at the same time as the hamstring even if it is not symptomatic. It doesn’t have to be painful to be the cause.
Other factors are age – the older you are the more likely; weakness in the hamstring so that it cannot cope with the forces you apply to it; Lack of flexibility meaning you more easily overstretch the muscle; fatigue causing poor coordination.
What happens in the muscle with a tear?
Muscle fibres, connective tissue (collagen) and blood vessels are ripped apart. The more that is torn the longer it takes to heal.
With a lot of damage then bleeding and haematoma or internal blood clot will form. A lot of bleeding over a big area usually means the fibrous sheath around the muscle has been torn too. This does not necessarily mean a longer recovery though.
The bruising will take about 2 weeks for the body to break down and disperse.