Stress Fracture Causes

High-impact sports have potential to cause stress fractures, and an awkward step can see stress fractures develop in the foot as a result if the impact is not severe enough to cause a full fracture or break. However by far the commonest cause of foot stress fractures is when the feet are subjected to repeated high forces when muscle conditioning is poor or insufficient.

The reason why otherwise normal forces cannot be dealt with effectively is typically due to overuse of the feet such as when athletes train too hard and too fast. When the duration of exercise is increased suddenly, exercise sessions increase in frequency substantially or the intensity of a training session is raised to a level which the feet are unable to cope with, it can all too easily cause foot stress fractures to develop. When the rest of the body is more than able to deal with such increases in effort, the feet are often the body parts which suffer the most, whether sprains and strains are suffered or stress fractures develop.

Intensity, Duration and Frequency of Exercise

Although athletes and avid sports enthusiasts are most at risk of developing stress fractures in the feet from overtraining, it is not only people who indulge in intensive training sessions who are at risk of developing stress fractures in the feet. It is not uncommon for an athlete or runner who has taken time away from training due to an injury to resume training at a similar level as before a break was taken. However, during the intervening time body condition may have deteriorated to a point where the muscles, ligaments and tendons have lost strength and are no longer able to deal with the same intensity of training as before the rest was taken.

Starting a New Exercise Regimen

Similarly, people who are just starting out with a new sport or a new exercise regimen after a long period of inactivity need to start slowly. It is all too easy to start too quickly and do too much too soon. Should the muscles in the feet become fatigued, this can cause excess forces to be transferred to the bones in the feet and stress fractures can develop all too easily.

Muscle fatigue is a major cause of foot stress fractures; however even minor ailments of the feet such as blisters can be a risk factor. A blister on the foot may not be a major ailment, but it can be sufficient to shift the weight distribution to avoid rubbing and pain. When the foot is placed in an unnatural position, the musculature of the foot is forced to function abnormally and can easily become prematurely fatigued. When that happens, forces which would normally be taken in the stride will see those forces transferred to the bones which are ill equipped to deal with them.


Foot Stress Fractures and Diet

A diet which is low in calcium is one of the major stress fracture risk factors, especially in children and teenagers. A calcium deficiency at an early age can have profound implications on bone strength. A calcium deficiency during the main growth phase can cause the early onset of osteoporosis and can result in brittle bones. This can cause a lifetime of health problems and can see the individual concerned plagued with stress fractures for life. Calcium is vital for the formation and maintenance of healthy bones and a calcium deficiency can easily cause stress fractures to develop.

Vitamin D is also essential for the growth of strong and healthy bones. One of the major sources of vitamin D is sunlight, with the vitamin D able to be synthesized by the skin in response to ultraviolet light. However, there are many factors which can affect vitamin d synthesis, such as when children spend the majority of their time indoors, or if they live in an area where daylight hours are shorter, and during the winter months when exposure to sunlight is minimal it is all too easy for a vitamin d deficiency to develop if the body has not managed to store sufficient levels. It is wise to ensure that sufficient quantities of this vitamin are consumed, or that vitamin D supplements or multivitamins are taken especially during winter months. Vitamin D is not used directly in the formation of strong bones, but it is vital in order for calcium to be able to be absorbed. A vitamin D deficiency can be a major causative factor in the development of stress fractures

Eating disorders lead to poor nutrition and are common in female athletes who are trying to control their weight. The problem is often compounded by an avoidance of foods which are deemed to be fattening, which include the most plentiful sources of dietary calcium such as dairy products. Vegans are also at a particularly high risk of developing a calcium deficiency if a replacement source of dietary calcium is not consumed. Eating disorders form part of the female athlete triad, which is a major contributor to the likelihood of developing stress fractures in teenage girls and female athletes.

Footwear Choice and Foot Stress Fractures

Sometimes the cause of foot stress fractures can be as simple as footwear choice; however mistakes can all too easily be made with the choice of footwear which can increase the risk of developing foot stress fractures. One of the most common problems for athletes, runners and sports enthusiasts is that the correct footwear is chosen but athletic shoes are not changed frequently enough. Modern athletic shoes are designed to provide the highest level of cushioning to the feet, they are capable of assisting the arches absorb shocks, assist with the prevention of foot fatigue and cushion the feet from hard heel impacts.

However, over time the materials inside the shoe degrade. In particular the EVA foam rubber and Polyurethane used in the construction of the midsole of the shoes degrades far more quickly than the hard wearing uppers. From the outside, athletic shoes may look like they have plenty of life left in them, while inside the midsoles may have degraded to the point that they provide little to no arch support, heel cushioning or shock absorption.

Running shoes need to be replaced every 500-700 miles, and new shoes need to be broken in before they provide the optimum level of cushioning. Athletic shoes also need to be chosen for the specific activity in mind, as only then can the user be guaranteed that they will be up to the task at hand.

Underlying Problems Which Can Cause Stress Fractures in the Feet

There are 26 bones in each foot which include some of the smallest in the body; yet these bones are normally able to withstand considerable forces without developing fractures. However any disease which causes weakening of the bones will make the development of stress fractures all the more likely. Weakened bones are more likely to break or fracture when the forces generated during even normal levels of exercise place stresses on weak spots. The most common disease which causes insufficiencies in weight bearing bones is osteoporosis; a common condition in women over the age of 50. It has been estimated that as many as one in five women in this age group suffer from osteoporosis to some degree. However osteoporosis can affect younger women, especially when there is poor nutrition.

Diseases and health conditions which can cause weakening of the bones include:

  • Anorexia Nervosa
  • Bulemia Nervosa
  • Metabolic Bone Disease
  • Osteogenesis Imperfecta
  • Osteomalacia
  • Osteopenia
  • Osteopetrosis
  • Paget’s Disease
  • Rickets
  • Vitamin D deficiency
  • Calcium deficiency

Some drug treatments such epilepsy medication can cause the bones to weaken, irrespective of vitamin D levels and calcium intake.

Stress Fractures and the Flat-Footed

Sufferers of flat feet are especially prone to stress fractures of the foot, and while high quality athletic footwear will help to give adequate support, this may not be sufficient in itself. Specialist running shoes are available to suit all foot types; however flat footed runners may benefit from wearing insoles with more substantial arch support or may benefit from arch support socks. Orthotic inserts can be a wise investment for flat footed or heavy footed runners to boost support and lessen the risk of developing foot stress fractures.