Stress fracture

Symptoms

Lower limb stress fractures are very common among runners due to the repetitive stress. The symptoms of a stress fracture are pretty clear: localised pain (aching or burning) somewhere on a bone. The pain will increase if you touch the specific area and will get worse when you run.

Causes

All tissues in our body adapt to the repetitive stress generated by running. Muscles and tendons need less time to modifies their mechanical properties. Bones, on the contrary, need months to adapt and strengthen. Therefore, high loads on your bones can create fractures.

What does science have to say?

Of course researchers have studied stress fractures. Here are some key facts:

• Vertical loading rate was found to be significantly higher in runners with stress fractures (1)
• Barefoot runners with a mixed landing pattern may sustain higher loading rates, compared with those who completely avoided heelstrike pattern (2)

How to avoid it?

It is pretty clear in the literature that stress fractures are correlated with high stress in the region where the fracture occurred. Higher forces and loading rates are primary risk factors for stress fractures. If you are a rear foot striker, stress will be applied primarily in your heel, tibia and knee. It you strike with your mid foot or front foot, a much higher stress will be applied in your metatarsal heads (i.e. your front foot bones).

Impact forces and loading rates can increase greatly if you fatigue. Your technique is therefore crucial to avoid stress fractures. Measuring and monitoring both impact forces and loading rates are crucial to avoiding fractures.

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with stress fractures. As your personal running coach, FeetMe Sport tracks your risk of injury.

Iliotibial band syndrome

Symptoms

Iliotibial ban syndrome (ITBS) is a very common injury among runners. It is characterised by a stinging sensation on the outside of the knee. Pain might not arise at the beginning of your run, but it may get worse with time. If you have ITBS, you will feel the pain at its maximum intensity when you knee is bended at 45 degrees.

Causes

The iliotibial band is thick tissue on the external side of your knee which runs from your pelvis to the bottom of your knee. While you run, the iliotibial band moves from behind the femur to the front of the femur. This repetitive movement can cause inflammation of the tissue if there is stress associated.

What does science have to say?

ITBS has been widely studied by researchers, here are some key facts:

• Maximum supination velocity, maximum braking force,  weekly mileage and maximum normalized braking force are significant discriminators for ITBS (1)
•  Increasing step width during running, especially in persons characterized by a narrow step width, may be beneficial in the treatment and prevention of ITBS (2)
• Subtalar joint eversion (i.e. pronation) was significantly lower at touchdown in the ITBS (3)
• Runners with ITBS have a greater peak rearfoot invertor moment  (i.e. supination) (4)

How to avoid it?

Researchers have demonstrated that ITBS is highly correlated with supination. A supinator will have his knee naturally bended towards the external side. In that configuration, the iliotibial band will rub against the femur at every stride, causing the inflammation and the pain. It is therefore crucial to measure your pronation/supination continuously to make sure you can deal with ITBS and avoid getting injured.

Step width might also be linked to ITBS but there are fewer proofs demonstrated this correlation.

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with Iliotibial band syndrome. As your personal running coach, FeetMe Sport tracks your risk of injury.

Plantar fasciitis

Symptoms

Plantar fasciitis is a condition characterised by pain in the heel or along the arch of the foot. Pain is usually worsened by moving your toes towards your tibia. You will feel the pain mainly after a long rest (especially in the morning) but tends to disappear after the location is warmed up.

Causes

The plantar fascia is a tissue supporting the arch on the plantar side of your foot. It runs from the heel (calcaneus) to the front foot (metatarsal heads). Plantar fasciitis is caused by overload and excessive stress on the plantar fascia.

What does science have to say?

Here are some key facts on plantar fasciitis:

• A significantly greater maximum instantaneous load rate was found in the plantar fasciitis athletes (1)
• In the acute stage of plantar fasciitis, runners presented lower loading rate and forces over the rearfoot (2)
• Decreased propulsive ground reaction forces are suggestive of compensatory responses (3)
• High-load strength training may aid in a quicker reduction in pain and improvements in function (4)
• Using minimalist shoes will get a worse outcome compared to staying in the shoes you got the injury in (5)

How to avoid it?

From the literature, the main parameters which can cause plantar fasciitis are higher propulsion force and loading rate as they both increase the stress on plantar fascia. However, in the acute phase of the injury, compensatory responses can result in decreased propulsion force and loading rate.

Front foot strikers may have greater risk of injury concerning their plantar fascia. But there are only rare articles studying this correlation.

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with plantar fasciitis. As your personal running coach, FeetMe Sport tracks your risk of injury.

Achilles tendinitis

Symptoms

The Achilles is the large tendon of the back of the leg which attaches two muscles (gastrocnemius and soleus) to the heel bone (or calcaneus). Achilles tendinitis is an inflammation of the Achilles. Symptoms can vary from pain or burning in the ankle.

Causes

High and repetitive stress on the Achilles can cause the inflammation. The Achilles has poor blood supply which can lead to degradation of the fibers forming the tendon. Various biomechanical characteristics can create stress in the Achilles.

What does science have to say?

Researchers have studied the Achilles tendinitis, here are some key facts:

• Non-rearfoot strike pattern results in increased loads and loading rates in the Achilles tendon (1)
• Foot overpronation may affect Achilles tendon blood flow thus enhancing the possibility for injury (2)
• Minimalist footwear may increase runners risk for Achilles tendon injury (3)
• Higher impacts caused by fast training sessions lead to excessive stress on the Achilles tendon (4)

How to avoid it?

Researchers have demonstrated that Achilles tendinitis can arise from numerous factors.

Forefoot striking increases the load on Achilles tendon which can cause an inflammation, thus Achilles tendinitis. More precisely, a rapid change in foot strike modifies drastically the stress on Achilles and can deteriorate the fibres constituting the tendon. Minimalist footwear also modifies the foot strike towards a more forefoot strike pattern.

Overpronation and higher impacts will also increase the load on the Achilles which can cause fibres deterioration.

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with Achilles tendinitis. As your personal running coach, FeetMe Sport tracks your risk of injury.

Shin splints or medial tibial stress syndrome

Symptoms

Shin splints, also called medial tibial stress syndrome (MTSS) is characterised by a pain along the inner edge of the tibia. Shin splints should not be confused with stress fracture where the pain is localised on the fracture site.

Causes

Shin splints is usually caused by overloading in the lower leg due to irregularities which increase the stress on the tibia. With repetitive stress on the soleus (a muscle in the back part of your leg) become weakened which contributes to shin splints.

What does science have to say?

As shin splints represent one a the most common injuries in running, researchers have studied it broadly. Here are some key facts:

• Wider step widths were generally associated with reduced loading of the tibia (1)
• Runners with suspected symptoms of medial tibial stress syndrome should be assessed dynamically and statically for abnormal or mistimed pronation (2)
• Pronating foot configuration would be an shin splints risk factor (3)
•  An imbalance in foot pressure with greater pressure on the medial side than on the lateral side was the primary risk factor (4)
• Strong evidence that a pronated foot posture was a risk factor for medial tibial stress syndrome (or shin splints) (5)

How to avoid it?

Researchers have demonstrated that the primary risk factor for shin splints is over-pronating foot. Over-pronation can be caused by biomechanical constraints (i.e. your running style) or by fatigue during a run. So, even if you are a supinator, pronation can occur due to muscles exhaustion.

Step width can also be a cause of shin splints, but the proofs are less numerous in the literature.

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with shin splints. As your personal running coach, FeetMe Sport tracks your risk of injury.

Runner’s knee or Patellofemoral pain syndrome

Symptoms

Patellofemoral pain syndrome (PFPS), also called runner’s knee, is characterised by pain between the patella (or kneecap) and the femur. Symptoms include pain while sitting with bent knees, running downhill, descending stairs or squatting.

PFPS should not be confused with patellar tendonitis which is characterised by pain in the tendon between the kneecap and your shin.

Causes

PFPS is usually caused by an important increase in your running mileage or repetitive stress on your patella. Some runners will experience pain due to repetitive compressive or shearing forces. PFPS is also associated with poor quadriceps development which causes the abnormal forces applied on your patella.

What does science have to say?

Scientists have studied PFPS very widely as it is the most common of all running injuries. Here are key facts:

• Diminution of impact force and loading rate is associated with a diminution of symptoms related to PFPS (1)
• Runners with history of PFPS exhibit a higher impact force and loading rate than healthy runners (2)
• Higher peak force and loading rates are predictors to PFPS (3)
• Direct relationship between step length and PFPS joint loads (4)
• Forefoot striker exhibit lower patellofemoral stress which may reduce the risk of knee injuries (5)
• Changes in Vertical Ground Reaction Force combined with appropriate training advice could explain the reduced pain and improved function of runners with PFPS (6)
• The reduction in vertical load rates may be protective for the knee and reduce the risk for other running-related injuries (7)

How to avoid it?

Researchers have demonstrated that high impact force and loading rate are key predictors to PFPS. Therefore, measuring are reducing impact force and loading rate should be your main focus to avoid runner’s knee.

Forefoot striking has also be proved to reduce knee stress in general. It may be an option if you have recurrent knee injuries. However, forefoot striking generates higher stress on metatarsal bones (i.e. your forefoot) and in Achilles tendon.

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with PFPS. As your personal running coach, FeetMe Sport tracks your risk of injury.

Patellar tendinitis

Symptoms

Patellar tendinitis, or patellar tendinopathy, is characterised by a pain in the patellar tendon which runs from your patella (or your kneecap) to your tibia. Patellar tendinitis car lead to tear or degeneration of the tendon.

With patellar tendinitis, you will experience pain while descending stairs or running downhill. Pain can disappear after a short warm up, just in any tendon-related injury.

Patellar tendinitis should not be confused with Patellofemoral pain syndrome (PFPS) which is not sensitive to the touch.

Causes

Patellar tendinitis is caused by repetitive overloading in the knee extensor. Quadriceps tightness increase stress on your tendon and therefore cause patellar tendinitis. Patellar tendon experiences high forces during a run. Its inflammation is usually due to chronic stress due to repetitive movements (just like when you run).

What does science have to say?

Patellar tendinitis has been widely studied by scientists, here are some key facts you should know:

• Patellar tendinopathy is a diagnosis that is present in 5% of injured runners with 57% occurring in male runners (1)
• Forefoot strikers exhibit knee frontal plane moment than rear-foot strikers, which reduces the risk of running-related knee injuries. (2)
• Reduction in vertical load rates may be protective for the knee and reduce the risk for patellar tendinitis (3)

How to avoid it?

Researches have demonstrated that patellar tendinitis can be associated with high loading rates and impact forces. Those parameters induce enormous stress on the knee and especially on the patellar tendon.

Moreover, forefoot striking may reduce the overall load on the knee which will decrease the stress on your patellar tendon. However, forefoot striking will increase the stress experienced by your Achilles tendon and your metatarsal bones (your forefoot).

FeetMe Sport, is the ultimate running wearable and measures all key parameters related with patellar tendinitis. As your personal running coach, FeetMe Sport tracks your risk of injury.

Impact force, loading rate and pronation

What are those metrics?

Impact force and loading rate

Your gait is divided in different phases:

• When your foot is on the ground: absorption and propulsion phases
• When your foot is in the air: swing phase

Impact force if the force applied by your foot on the ground during the absorption phase. Loading rate is the speed at which the impact force is applied. Together they quantify the shocks sustained by your whole body.

Pronation/supination

Pronation refers to the inward roll of the foot, whereas supination is the opposite of pronation and refers to the outward roll of the foot.

How should I use them?

Impact force, loading rate and pronation/supination are mainly related to injuries. They do not have a direct role in performance.

We have a complete section which lists the most common injuries and their related metrics. Please refer to this section to get more details on how to use those metrics!

 

Foot strike: does it really matter?

What is foot strike?

Foot strike is the region of your foot that lands on the ground. It shows if you’re a heel-striker, midfoot-striker or forefoot striker.

The science behind foot strike

There has been many studies on foot strike. Here are key facts on foot strike:

• Forefoot striking increases metatarsophalangeal and ankle joint load but decreases knee load (1)
• Barefoot running was performed with higher cadence and shorter strides.(2)
• Rearfoot pattern may reduce Achilles tendon stress, strain, and strain rate (3)
• Even Kilian Jornet adapts his foot strike during a run (4)

How should I use it?

From a biomechanical point of view, rear foot striking is associated with higher knee load. On the other hand, fore foot striking creates higher mechanical constraints on the metatarsal bones (your front foot) and on Achilles tendon. Foot strike can therefore be associated with risk of injuries.

There are no clear conclusions on foot strike influence on running performance.

How can I measure it?

There are no tools outside of running labs to measure foot strike. They usually do this with video analysis or with force plates.

Being the ultimate running wearable FeetMe Sport can measure foot strike. It is a key parameter in evaluating risk of injuries. You’ll find more details on the injuries associated with foot strike in our Injuries section.

If you want to evaluate your foot strike and evaluate your risk of injuries, FeetMe Sport is exactly what you need.

Propulsion force: key phase in your gait

What is propulsion force?

Your gait is divided in different phases:

• When your foot is on the ground: absorption and propulsion phases
• When your foot is in the air: swing phase

The propulsion force is the force you apply on the ground during the propulsion phase of our swing. Therefore, it is the force that propels you forward.

The science behind propulsion force

The propulsion phase has been widely analysed by scientists. Here are key facts:

• Propulsive force is increased by greater forward leaning (1)
• Propulsive phase has the strongest direct link with running economy (2)
• Body weight support and forward propulsion comprises about  80% of the metabolic demand of running (3)
• Strides which are too long will require considerable power during propulsion (4)
• At slower stride rates (and longer stride lengths), the muscles need to develop high external power during propulsion to overcome large braking forces (5)
• Propulsive phase is key for running economy (6)
• Propulsion force is directly related to plyometric and resistance trainings (7)

How should I use it?

Propulsion force is a key parameter in your running stride. It will greatly influence performance and efficiency. There are two way of using propulsion force:

1. If you decrease your propulsion force while keeping the same speed, you enhance your running economy. You will run longer!
2. If you increase your speed but keep the same propulsion force, you are optimising the force you are generating. You will run faster without getting exhausted!

How can I measure it?

There are not many tools outside of running labs to measure propulsion force. Researchers use force plates which allow measuring one stride. FeetMe Sport is the ultimate running wearable and measures your propulsion force during any run.

Start measuring and optimising your propulsion force with FeetMe Sport go run more efficiently!