Risk factors

Hamstring injury risk factors include:

• Sports participation. Sports that require sprinting or running, or other activities such as dancing that might require extreme stretching, make a hamstring injury more likely.
• Prior hamstring injury. After you've had one hamstring injury, you're more likely to have another one, especially if you try to resume all your activities at pre-injury levels of intensity before your muscles have time to heal and rebuild strength.
• Poor flexibility. If you have poor flexibility, your muscles may not be able to bear the full force of the action required during certain activities.
• Muscle imbalance. Although not all experts agree, some suggest that a muscle imbalance may lead to hamstring injury. When the muscles along the front of your thigh — the quadriceps — become stronger and more developed than your hamstring muscles, you may be more likely to injure your hamstring muscles.