Stress fractures occur when repetitive stresses are applied to a weakened bone.
This is a chronic injury, which means that it does not happen from a one-time event,
but over an extended period. Improper equipment (worn or improper shoes), muscle
imbalances, or improper running and walking gait can all cause stress fractures.
The muscles are designed to act as shock absorbers during impact activities. They
take the stress off the skeletal system and the internal organs. When the muscles
become fatigued due to a workload that is more than they can handle they will no
longer be able to work as shock absorbers. The load is then transferred to the bones.
The force is transferred through the bone until it reaches a weak area where it
causes a small crack. Over time, that develops into a stress fracture. This process
is known as the fatigue theory.
When the human body is subjected to a slight increase in workload it will adapt
by getting stronger. The bones, tendons and muscles will all change to handle the
increase. If the workload is increased too quickly the body is unable to adapt quick
enough and the stress is transferred to the foundation of the body (the skeletal
system.) If there is a weakness in any part of the skeletal system this increase
in stress will cause it to succumb to the pressure and crack. This process is known
as the overload theory.
Symptoms
Symptoms of stress fractures are fairly focused. Pain usually increases with weight
bearing activities and diminishes with rest. Pain is most severe at the beginning
of the activity then subsides in the middle of the activity and increases in severity
near the end. The pain continues as a dull throb after the activity. Swelling and
point tenderness around the site of the fracture may also occur. The pain will gradually
get worse and may occur earlier in the workout over time. If left untreated the
pain may become unbearable.
Prevention and Treatment
Due to the extended recovery time (6-10 weeks), preventing stress fractures is of
major importance. Gradually increasing workloads at a rate of no more than 10% a
week and varying the training by using cross training techniques will help to off
set the overload and repetition often associated with stress fractures.
Warming up properly and preparing the body for the workout will help to keep the
muscles from fatiguing as quickly. This will also prevent injuries to the muscles
and tendons, which could lead to further weakening of the bones. Injuries to the
muscles, tendons or ligaments that support the skeletal system could lead to excess,
and awkward, pressure on the bones.