Understanding muscle strength

This week the NCAA Track and Field Championships are in Austin, Texas.

The best collegiate track and field athletes are competing for a national championship.

There are two things that these athletes have to reach this level of competition. One is a hard work ethic to attain the best limit of their ability. The second point to reach this level is that they were injury free. The athletes have to push their bodies to an extreme limit to win against the other high achieving athletes in the competition.

It is at this level of completion that any muscle imbalance or weakness is one cause of an injury. In the sprint events up to the 400 meters one injury that will eliminate most athletes from the competition is a hamstring strain (pull).

An injury in hockey that will also take an athlete out of the game for several months is a lower abdominal strain. Two different injuries but both have the same cause.

The problem is a muscle imbalance between the hip flexor muscle (ilio-psoas) and the abdominal muscles.

The usual imbalance is a strong hip flexor and a weak lower abdominal muscle. The ilio-psoas muscle attaches to the lower lumber vertebrae and the inside of the pelvic girdle and inserts on the inside of the upper thigh bone (femur). The action is flexion of the upper leg or flexion of the trunk. The abdominal muscle has the action of flexion of the upper body in a curling motion. Think of trying to touch your ribs to the pelvic bone motion. Where the injury occurs is when the ilio-psoas is stronger than the abdominal muscle and the result is an anterior (forward) pelvic tilt. When the pelvic girdle has an anterior tilt the result is a stretch on the abdominal muscles and the hamstring muscles.

A somewhat complex problem is that a fast runner needs a strong ilio-psoas to bring his or her leg up faster and have a higher knee lift. With an anterior pelvic tilt the back part of the pelvic bone is now higher and the hamstring muscle that is attached to the pelvic girdle (the ishium–the bone you sit on when seated), is now put on a slight stretch.

When the athlete has a high knee lift and then straightens the leg out to move forward the hamstring that is already on a slight stretch is put on a greater stretch. During the race the muscle will tire and tighten up and with the extreme stretch it may tear. When you see an athlete grab the upper portion of the back of their leg the cause is not necessarily a tight hamstring but a weak abdominal muscle.

This is where the abdominal muscle plays a key role in injury prevention. When the ilio-psoas muscle contracts it brings its two attachments closer together. The abdominal muscle acts as a stabilizer (a muscle that holds the bone in place for the muscle that is moving to pull against).

If the abdominal muscle is weak it allows the anterior pelvic girdle to tilt. If the result is creating an anterior pelvic tilt the pulled hamstring injury is possible.

To test the strength of the lower abdominal muscle as a stabilizer is needed. Have the athlete lie on their back with their legs pointing up toward the ceiling. Tell the athlete to put the small of the back tight against the floor and hold it. Tell the athlete to keep that pressure on the floor while they slowly lower their legs to the floor.

If the low back lessens pressure or comes off the floor it means the abdominal muscle is not able to hold the pelvic girdle steady against the pull of the ilio-psoas that is pulling up on the lower spine resulting in an anterior tilt.

A rough measurement is estimating the angle of the legs being lowered when the low back comes off the floor. An example is if the legs are half way down (a 45 degree angle) think that the lower abdominal muscle is only 50% of necessary strength. I tested some athletes that have the pressure on the low back lessen at a 15 degree angle. These athletes have a strong possibility of a hamstring strain during one of their extreme efforts to run faster.

In hockey it is the lower abdominal muscle that gets injured. With a strong ilio-psoas and a heavy skate on the end of a long leg the injury occurs when the leg reaches the end of its range of motion. The resulting pull against the pelvic bone is great. A hockey ‘slap’ shot has the momentum of the leg movement creating a pelvic tilt. If the pelvis tilts the abdominal muscle is put on a stretch and a slight tear may result.

The next game has the athlete doing the same motion with an injured muscle and the tear becomes enough to take the athlete out of the game.