The hamstrings are major movers of your lower leg and perform 3 main actions when they contract. The 3 muscles of the hamstrings: the semitendinosis, semimembranosus and the biceps femoris. They begin from the lower portion of the hip bone and attach in various spots just below the knee joint on either the tibia or the fibula.
The three main actions the hamstrings perform are:
- They serve to flex / bend the lower leg at the knee
- They assist in extension of the leg at the hip
- When the lower extremity is fixed they help in extension of the back
Having undertrained hamstrings can cause injuries if your quadriceps muscles (quads) are too strong comparatively and the ratio is skewed far off of a 2:3 ratio. When this happens and the quads are over developed and the hamstrings are under developed, your knee becomes susceptible to injury. While the knee joint is stabilized by the ACL, PCL, MCL and LCL ligaments, the muscles around it assist in stability with co-contraction. There have been numerous academic studies confirming the significance of proper hamstring strength, especially as it relates to reducing the amount of force put on the ACL.
For non-sports individuals, it has been shown that having strong hams and quads significantly reduces arthritic and/or degenerative changes. And in addition to power, having a balanced quads to hams strength ratio keeps an optimum level of co-contractive force to keep your knee running smoothly.
Check out our great hamstring exercise video. Most can be easily done at home with minimal equipment. Focus mainly on slow control of the hamstrings as you do these and if you need any clarification or additional help come see me!