Why do Muscles Strain?

Muscle injuries or ‘strains’ can be painful and stop you from doing the activity you love. There are a number of potential causes including:

  1. Muscle overload: where the muscle is stretched beyond its capacity or challenged with a sudden load.
  2. Eccentric contractions: when the muscle is lengthening as it is contracted eg during sprinting the hamstrings are lengthened and loaded as the back leg pushes off to propel the runner forward.
  3. Muscle tightness: tight muscles are vulnerable to strain.
  4. Muscle imbalance: the opposing muscle group (eg quadriceps) can be more powerful and during high-speed activities the hamstrings can become fatigued faster than the quadriceps. Fatigue reduces the energy-absorbing capabilities of the muscles – making them more susceptible to injury.
  5. Poor conditioning: If your muscles are weak, the will fatigue quicker. As above, they are less able to cope with stress.


If a muscle strain is not addressed appropriately, muscle fibers can re-knit incorrectly, exposing a functional weakness in the already compromised muscle. This can increase the risk of re-injury and long-term dysfunction. Physiotherapy treatment and a graded rehab program is paramount to promote optimal healing and negate the chance of chronic issues.