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Stress Fractures

Lower Limb Bones

 

Stages of Stress Fracture

Bone Stress Injuries

Bones are very important and have many functions, including movement, structural support, protecting organs, storing minerals and creating blood cells.

Our bones remodel all the time (new bone forms and damaged bone is resorbed), this happens when bone comes under stress through walking, running and other activities which cause impact stress on bone. Microdamage is normal when these activities are undertaken and normal levels of remodelling occurs if your body is tolerating these exercise loads well.

Bone stress injuries (BSI) occur when there is an imbalance between bone being formed and resorbed due to exercise loading. This can result in stress reactions or stress fractures. Other factors that play a role in BSI inadequate recovery and sleep, nutrition, low energy availability OR Relative Energy Deficiency Syndrome (RED-S), training errors and underlying medical conditions. Females are also at greater risk of BSI and depending on sports played, this may also place you at greater risk of developing a bone stress injury in a certain area. BSIs are classified in to high and low risk categories due to where the bone comes under tension or compression on its bending axis and blood supply available to aid in healing the effected bone.

High Risk Bone Stress Injuries

  • Femoral neck
  • Anterior cortex of tibia
  • Medial Malleolus
  • Talus (lateral process)
  • Navicular
  • 5th Metatarsal (proximal diaphysis)
  • 2nd Metatarsal (base)
  • Big Toe (sesamoids)

Low Risk Bone Stress Injures

  • Posteromedial tibia (shin)
  • Fibula/lateral malleolus
  • Femoral shaft
  • Pelvis
  • Calcaneus
  • Diaphysis of 2nd to 4th metatarsals
  • Big Toe (sesamoids)

If accelerated bone remodelling occurs (where resorption is greater than bone formation) normal adaptation does not take place and the risk of BSI increases. Stress reactions are graded 1, 2 or 3, before stress fracture (grade 4) and finally complete fracture.  If there is a high clinical suspicion of a BSI then an MRI may be undertaken to confirm and grade the injury. Depending on the grade of bone stress injury and presenting clinical history, will determine the timeframe for a return to activity.

Management of Bone Stress Injuries

Depending on the clinical signs and symptoms and potential MRI findings will determine the management and treatment plan for BSI. If you have suffered a Grade 4 injury at a high risk site such as the Navicular this may involve complete non WB activity (CAM walker boot and crutches), where as a Grade 1 Injury at a low risk site may involve relative rest from aggravating activities such as  running and other weightbearing sports and activities for 4-6weeks.

Management also needs to address why a BSI has occurred. This may involve addressing biomechanics, training patterns and footwear to help modify bone loading. As well as addressing factors that influence the bones ability to resist load such as overall bone health status, energy availability (RED-S), sleep, nutrition and other psychological and emotional stressors in everyday life. This may involve referral to a GP, dietician or sports psychologist.

After sufficient time has been given to heal the effected bone and other contributing factors to the BSI have occurred have been addressed then a gradual bone loading program can be introduced to help load and strengthen the bones to help reduce the risk of BSI reoccurrence.

References

Epidemiology of bone stress injuries in Australian high-performance athletes: A retrospective cohort study

Ruddick, Gemma K. et al.

Journal of Science and Medicine in Sport, Volume 22, Issue 10, 1114 – 1118

 

Nattiv, A., Kennedy, G., Barrack, M. T., Abdelkerim, A., Goolsby, M. A., Arends, J. C., & Seeger, L. L. (2013). Correlation of MRI grading of bone stress injuries with clinical risk factors and return to play: a 5-year prospective study in collegiate track and field athletes. The American journal of sports medicine41(8), 1930-1941.

Correct Training - Exercise, Load and Capacity

Tendon Overload

 

 

Loading Capacity Model

Walking and running are excellent, cost-effective ways of getting outdoors and keeping fit and healthy. We are all aware of the physical and mental health benefits these can bring but often we are time poor and finding that extra time in our busy lives can be hard.

For those who are at the start of their walking and running journey or those who are looking to take it to the next level during this time, a sudden spike in either activity may increase your risk of injury.  The best and simplest way to reduce this risk is by gradually increasing the amount you walk or run on a week to week basis so that your bodies capacity can adapt to your new walking and running loads.

 

Training Load and Capacity

Load refers to your volume (how much), frequency (how often), intensity (how hard) and type as well as stress, anxiety and what else you do in your day to day life (work, inconsequential walking, habits, hobbies etc).

Whereas capacity refers to the different tissues in your body responsible for performing the movement and their ability to handle your day to day loads (Strength, control, biomechanics, previous injury history etc).

 

Background

Lower limb injuries (plantar fasciitis, posterior tibial tendinopathy, Achilles tendinopathy and others) are common runners and walkers who are starting out. According to Klutinberg et al (2015)  up to 85% of novice runners experience a running injury that results in time lost from running.

Footwear and biomechanics are easy to attribute to the cause of injury (and definitely can contribute!), but often it is doing too much too soon and exceeding the capacity of the tissue that brings on the injury. This can be frustrating as it often strikes when you feel as though you are making progress with your exercise related goals.

Not being able to exercise can impact on your physical and mental health during an already tough and uncertain time. In order to reduce the risk of injury a gradual increase in exercise is often considered the best place to start.

 

Getting Started

For those new to running or looking to walk more, your previous activity levels can play a role in determining your capacity to tolerate these activities and this can vary from person to person. Have a go at a few short runs/walks (or a combination of both) for 2or 3 times during the first week and give yourself 24-48hours rest to recover.

Gradually increasing your volume by ~10% per week is a good place to start. This gradual increase in load will help build capacity of joints, muscles and tendons used in walking and running and reduce injury risk. If you are running you don’t need to go 100% on every run, take the foot off the pedal – this will reduce soreness and have you ready and raring to go for your next run.

As you build your load and capacity the best way to reduce injury risk is to increase one variable at a time. During this phase focus on volume (the amount you walk/run) at a comfortable pace and increase frequency, intensity and type of training later. 

 

For those on their way

For those who have been running for a while, for example a couple of times per week (15km +) but are looking to increase their running volume or spend their time in social isolation training for their first race, a gradual increase is still the best. The 10% Rule,  a 10% increase in volume or frequency or intensity per week is a good starting point for most people.

Increasing your load whilst following the 80/20 rule where 80% of the total weekly volume is done at an ‘easy pace’ and 20% is done at a high intensity (Seiler, 2010) . This is important because as you increasing volume it is important not to increase too many variables (speed, distance, hills, training surface) at once.

Remember you still need to recover from your runs and listening to your body is important as your body get used to the increase in exercise. If you are looking to incorporate more intensity (speed) into your running then try to keep it under 20% of your total mileage!

 

Other considerations

Other factors also play a role in your walking and running and potential risk of injury, including age, BMI, biomechanics, life stressors, sleep, recovery, diet/nutrition and footwear. Keep these in mind as you gradually build your load as they can play an important role in determining your current capacity.

No matter whether you are a walker or runner, where you are on your fitness journey and your previous experience it is important to know that if you increase your load to quickly your risk of injury increases too. A gradual increase ~10% is a good place to start and try not to adjust too many variables at once.  Remember other psychosocial factors can increase your load and test your capacity.

 

References

Dallinga J, Van Rijn R, Stubbe J, et al Injury incidence and risk factors: a cohort study of 706 8-km or 16-km recreational runners BMJ Open Sport & Exercise Medicine 2019;5

Goon, T. (2016, April 11). Balancing training loads and tissue capacity [Blog post].

Kluitenberg, B., van Middelkoop, M., Diercks, R. et al. What are the Differences in Injury Proportions Between Different Populations of Runners? A Systematic Review and Meta-Analysis. Sports Med 45, 1143–1161 (2015). 

Linton, Linda et al.

Running with injury: A study of UK novice and recreational runners and factors associated with running related injury Journal of Science and Medicine in Sport, Volume 21, Issue 12, 1221 - 1225

Seiler S. What is best practice for training intensity and duration distribution in endurance athletes?. Int J Sports Physiol Perform. 2010;5(3):276–291.