How to Prevent Stress Fractures While Running, According to Science

It’s all too common of a tale: a runner starts training for a marathon. Their weekly mileage rapidly doubles, but they feel great for a couple weeks. Then, they start experiencing an ache in their calf. The ache doesn’t go away with stretching or ice, but instead keeps worsening. They stop running and visit their doctor, and learn that they have to stop running for eight weeks due to a stress fracture. While it’s a common scenario, this does not have to happen to you. This article dives into the most recent research on stress fractures and running, so you can understand how to prevent stress fractures – and how to recover if you do get one.

The reality of running and stress fractures

Stress fractures are a widespread injury for runners, occurring as up to 20% of running-related injuries. However, do not mistake the prevalence of stress fractures to mean that they are an inevitable part of running. You can take measures to prevent stress fractures, including training load management, appropriate nutrition, and enough sleep.  

A stress fracture is when a tiny crack appears in the bone. This crack does not go all the way through, but it could progress to a full fracture if not treated. Stress fractures occur when bone remodeling does not occur quickly enough to support repetitive loading. A stress fracture can happen due to excessive training or due to the bones themselves being too weak for the training load.

How to avoid a stress fracture

A 2024 cross-sectional study in Orthopedic Journal of Sports Medicine examined factors associated with bone stress injuries in runners. From the findings, we can understand the potential causes of bone stress injuries –  and how to prevent stress fractures. Most factors are controllable: sleep, nutrition, strength training, and proper run training.

Maintain a healthy bone density

The 2024 study validated what many previous studies found: poor bone health increases the risk for a bone stress injury. This study found that runners who had lower z-scores in their spine (worse bone density) also had a higher risk of bone stress injuries in the pelvis, sacrum, and femoral neck. 

While running itself is neutral to slightly beneficial for bone building, it is not enough to build total body bone density. A 2012 study in Current Sports Medicine Reports indicates that runners typically have higher bone mineral density at the points of impact – foot bones and tibia – but that running was not enough to improve bone mineral density in the femur or other bones closer to the spine. 

How can runners improve their bone mineral density to prevent stress fractures?

• Consistently lift weights two to three times per week. You should include exercises that target both the upper body and lower body. Spine-loading exercises (squats, deadlifts, etc) are favorable for improving bone mineral density.  
• Include plyometrics in training. Plyometrics apply high forces very quickly, which promotes bone growth.
• Ensure you consume adequate amounts of vitamin D and calcium in your diet. 
• Eat enough total calories and carbohydrates (more below)

Related: Strength Training for Runners

Eat enough to support your training

A seminal 2020 review in Nutrients analyzed the effects of low energy availability (LEA) in athletes – and found that chronic under-eating impaired bone health. Athletes with low energy availability were 4.5x more likely to experience bone stress injuries. When an athlete undereats, their body prioritizes necessary physiological functions – which means that the bones do not receive enough resources to repair from training load. 

LEA causes menstrual dysfunction in female athletes, which lowers estrogen levels. Since estrogen promotes bone strength and reduces bone breakdown, low estrogen levels can decrease bone mineral density. Amenorrhea in runners (no period) indicates a state of low energy availability and a higher risk of bone stress injuries. 

However, male athletes can also experience impaired bone health due to low energy availability. A 2023 cross-sectional study in the Journal of Clinical Endocrinology and Metabolism determined that male runners had lower z-scores in the spine and a higher risk of bone stress injuries if they trained in a caloric deficiency. 

It’s not just total calories that matter – carbohydrates matter too. If you are following a low-carb diet as a runner, you are still at increased risk for a bone stress injury. A 2022 study in the Journal of Bone Mineral Research found that endurance athletes who restricted carbohydrates had reduced markers of bone formation, even if they ate enough total calories. In comparison, adequate carbohydrate intake promotes a favorable balance of bone resorption and formation.  

You must eat enough calories and carbohydrates relative to your energy expenditure to prevent stress fractures. The more you run, the more calories you burn, and the more you need to eat. 

Many runners fear that eating more will lead to weight gain. If you are eating appropriately to your training load, that is simply not the case. (The exception is if you were too thin due to under-eating – you may gain weight, but it’s weight that will support bone health and performance. Thinner is not faster, especially if you are chronically injured.) 

How much should you be eating? This guide from registered sport dietitian Featherstone Nutrition provides a reference to understand how much carbs, protein, fats, and total calories you should eat based on your training volume. 

• Pre-Run: 25-75 grams before runs <60 min; 60-100 grams before runs >60 min
• During runs of >75-90 minutes: 30-90 grams of carbs per hour
• Daily: 5-7 grams of carbs per kilogram of body weight

Sleep 7-9 hours per night

Chronic sleep deficits will increase your risk of experiencing a stress fracture from running. Broadly speaking, inadequate sleep increases risk for all running-related injuries, as sleep promotes recovery and immune function. 

The above-cited 2024 cross-sectional study found that female athletes who consistently slept less than 7 hours per night were significantly more likely to experience a high-risk bone stress injury. Inadequate sleep impairs bone metabolism, causing up to 5% bone mineral density loss.

Sleeping 7-9 hours per night is a protective measure against stress fractures. Additionally, good sleep is associated with improved running performance. If it comes down to fewer miles and more sleep, you are better off running less and getting adequate sleep. 

Increase training load gradually 

The musculoskeletal system adapts to training intensity and volume at a slower rate then the aerobic system. When you increase your mileage or do harder workouts, you will aerobically feel ready for more before your bones are. All too often, runners rapidly increase their mileage – only to end up in a boot for several weeks. 

Gradual increases in training load are a prudent measure to prevent stress fractures. This approach is particularly salient if you are returning from injury, training for your first marathon, or reaching a new weekly mileage. Give your bones time to adapt to the training load before increasing mileage too much. 

Related: How to Safely Increase Your Weekly Mileage

Does Your Gait Impact Your Risk?

Many runners blame a stress fracture on their running form. However, gait may not play as significant a role as the above factors. Some evidence indicates that higher loading rates may increase the risk of stress fractures in the tibia and foot bones. However, the 2024 study points out that this is not definitive; this study found no differences in loading rates when comparing female runners with high-risk bone stress injury (BSI), low-risk BSI, and no BSI injury.

How to tell if you have a stress fracture

The only method for diagnosing a stress fracture is an MRI. A full fracture will appear on an X-ray. However, since a stress fracture is a bone stress injury that has not fully broken through, it will only appear on an MRI. 

You cannot diagnose a stress fracture on symptoms alone. However, you should stop running and pursue a stress fracture diagnosis if:

• Pain during a run that persists or worsens as you go
• Unilateral pain (for example: pain in one shin, not both)
• A sharp or tender pain, often localized
• Pain during rest or daily activities
• Swelling at the pain site
• Gait alterations when running 
• Pain during the hop test (hopping a few times on the injured leg)

How to Know If It’s a Stress Fracture or Other Injury

A stress fracture from running can be a confusing injury. The pain may mimic other injuries, with symptoms such as muscle tightness. So how do you know if you have a stress fracture vs tendonitis (or another injury)? 

Stress reaction vs. stress fracture

A stress reaction and stress fracture are both bone stress injuries. The difference between the two is the severity. A stress reaction is the early stage of a stress fracture. Stress reactions often present as muscle tightness around the injured area. 

If you continue to run on a stress reaction, it will progress into a stress fracture (or even a full fracture). Generally, a stress reaction requires two to four weeks off of running. It is better to take those two to four weeks off than risk a worse injury and longer training layoff. 

Stress fracture vs. tendonitis 

Tendonitis (more properly called tendinopathy) is when the tendons (tissue connecting muscles to bones) become weak and/or inflamed, leading to declined function and pain. Unlike a stress fracture, tendinopathy does not involve any injury to the bone itself. The treatment for tendinopathy is different than that of a stress fracture. 

However, stress fracture symptoms can mimic tendinopathy symptoms in some cases. For example, a sacral stress fracture could initially present similar to high hamstring tendinopathy. Since treatment for the two differs significantly, it is essential to visit a PT or sports medicine doctor for an accurate diagnosis. 

Plantar fasciitis vs. stress fracture

Similar to tendinopathy, plantar fasciits is not a bone stress injury – but its symptoms can be similar to a calcaneal stress fracture. Plantar fasciitis presents as pain in the arch of the foot. In either case, if your heel hurts when running, it is prudent to stop running and cross-train until you can see a podiatrist or physical therapist. 

The recovery time for stress fractures

The location of the stress fracture does inform the recovery timeline. There are two types of bone stress injuries: low-risk and high-risk.

Low-risk BSIs are often located further away from the spine, such as the tibia, fibula, metatarsals, or other sites away from the spine. These stress fractures are less likely to progress into a full fracture. A low-risk BSI typically has a shorter recovery time. 

High-risk BSIs are located closer to the spine. A femoral neck, pelvic, or sacral stress fracture is classified as high-risk, as it could progress into a full fracture. High-risk BSIs require a longer recovery time. Additionally, a high-risk BSI statistically correlates with poor bone health in runners, which could further impact recovery time. 

A stress fracture may require 6 to 18 weeks off of running, based on a 2023 systematic review in the British Journal of Sports Medicine. Until tendinopathies, these are injuries where rest and deloading are essential for healing. If you do test runs, lift weights with the injured leg, or perform excessive cross-training, you may prolong the recovery or even experience a full break at the fracture site. 

 And no – KT tape on the outer side of a foot stress fracture will not expedite recovery. You can’t change shoes, have dry needling done, or do other things to make a stress fracture heal fast. The bone needs to be remodeled, which requires time, rest, and adequate nutrition. 

Your orthopedist or physical therapist will guide you through your individual recovery timeline. More than likely, you will have several weeks off, followed by a gradual return to run program. 

You May Also Like: How to Return to Running After Injury

Don’t let running and stress fractures sideline you

Stress fractures are not an inevitable part of running. You can reduce your risk of stress fractures by eating enough, supplementing vitamin D and calcium, lifting weights, sleeping 7-8 hours per night, and gradually increasing your training load.

 If you do experience symptoms of a stress fracture, stop running right away. You will need an MRI to diagnose a stress fracture. While you await the MRI, rest is the best choice for how to heal a stress fracture. Once your stress fracture is healed, you want to follow a conservative return to run plan. Depending on the site of the fracture, you may also want to consult a sports dietitian or start working with a strength coach to reduce further risk.