When sprinting, hamstrings undergo large force at extreme lengths. An eccentric contraction happens to the hamstrings on the front leg during sprinting right before foot contact. Once the foot hits the ground the force that comes with sprinting is now absorbed by the hamstrings. If the strength capacity of the hamstrings are not able to handle this force at that length at the time the foot contacts the ground; this is when hamstrings strain occurs, and is unnecessarily increased in ‘overstriding’.
Often seen in AFL (19% of hamstring injuries), when the hip is flexed, and knee extended under rapid and forceful conditions.
- Previous hamstring injury
- Lumbar lordosis
- Short hip flexors
Poor eccentric strength
If low capacity of strength in the hamstrings as a group, while the muscle is lengthening, is present, the increased chance of an injury occurring, as this capacity is exceeded, and this tissue fails.
Imbalance between hamstrings
If the medial hamstrings (semimembranosus & semitendanosouss) are weak or previously injured, then the lateral hamstrings (biceps femoris short and long head) may attempt to take the load. This can overload and cause tissue failure, as well as cause biomechanical deficiencies as it chances the way one moves.
To high speed running. This lack of exposure does not allow appropriate conditioning and adaptation to support gym based strength and can increase chances of injury.
If other hip extensors for examples gluteus maximus, are weak or inactive, then the hamstrings again may overload.
The above factors can be addressed through appropriate strategies, ideally before the fact through prevention, or after through rehabilitation. The Nordbord by Vald Performance, can be utilised to measures symmetry between limbs and eccentric strength, and the clinician can utilise their expertise to further diagnose and examine which area of the hamstrings is deficient or affected, and apply the ideal treatment or strategy to improve this.