A sports injury commonly occuring during a quick increase of speed: although this can also occur as an overuse injury or from a blow to the leg.

HAMSTRING INJURY
Hamstring injuries are common among runners, footballers and even brisk walkers. The hamstrings (muscles at the back of the thigh) work to slow down the leg as it swings forward. The risk of this injury increases with age.How do I know that I have a hamstring injury?
- Pain or cramping at the back of the thigh.
- Pain that is aggravated by
- Bending forward
- Sitting down,
- Driving,
- Walking, jogging or sprinting
Risk of hamstring injuries
- Increased sitting down – e.g. deskjob, driving
- Muscle imbalance – weak gluteal muscles and/or hamstrings
- Reduced flexibility
- Inadequate warm up
- Reduced fitness level