Some injuries runners can get: what AAOS and NHS pages say

Written by Dr Sean Leo, a consultant orthopaedic surgeon whose clinical focus is the knee, sports injuries and the lower limb.

Last updated: 9 October 2026.

Most stress fractures are caused by overuse and repetitive activity; they are common in runners and athletes who participate in running-intensive sports, such as soccer and basketball ^[7]. Achilles tendinitis is a common condition that occurs when the large tendon that runs down the back of the lower leg becomes irritated and inflamed ^[5].

On its general page about sprains, strains and other soft-tissue injuries, which is not specific to running, AAOS OrthoInfo says injuries often occur when people suddenly increase the duration, intensity, or frequency of their activities ^[1]. The same page says fatigue and pain are good reasons not to exercise ^[1].

This page describes six conditions that AAOS OrthoInfo and the NHS write about. The sources read for this page do not rank them.

• What is runner’s knee?
• What is an ankle sprain?
• What is plantar fasciitis?
• What is Achilles tendinitis?
• What are shin splints?
• What is a stress fracture?
• What about shoes and training?
• When is urgent help needed?
• What should I do next?

What is runner’s knee?

Patellofemoral pain syndrome (PFPS) is a broad term used to describe pain in the front of the knee and around the patella, or kneecap. It is sometimes called “runner’s knee.” ^[2]

Problems with the alignment of the kneecap and overuse from vigorous athletics or training are often significant factors ^[2].

More on kneecap pain

AAOS OrthoInfo lists these among the common symptoms of PFPS:

• Pain during exercise and activities that repeatedly bend the knee, such as climbing stairs, running, jumping, or squatting ^[2].
• Pain on the front of the knee after sitting for a long period of time with your knees bent ^[2].

What is an ankle sprain?

An ankle sprain occurs when the strong ligaments that support the ankle stretch beyond their limits and tear ^[3].

More on ankle sprain symptoms

Symptoms may include:

• Pain, both at rest and with weightbearing or activity ^[3].
• Swelling ^[3].
• Bruising ^[3].
• Tenderness to touch ^[3].
• Instability of the ankle, or a feeling that your ankle is giving out ^[3].

What is plantar fasciitis?

Plantar fasciitis is caused by straining the part of your foot that connects your heel bone to your toes (plantar fascia) ^[4].

The main symptom of plantar fasciitis is pain on the bottom of your foot, around your heel and arch ^[4].

What is Achilles tendinitis?

Achilles tendinitis is a common condition that occurs when the large tendon that runs down the back of the lower leg becomes irritated and inflamed ^[5].

The Achilles tendon is the largest tendon in the body. It connects the calf muscles to the heel bone and is used when you walk, run, climb stairs, jump, and stand on your tip toes ^[5].

More on Achilles tendinitis

AAOS OrthoInfo lists these among the common symptoms:

• Pain and stiffness along the Achilles tendon in the morning ^[5].
• Pain along the tendon or back of the heel that worsens with activity ^[5].

AAOS OrthoInfo lists these among the factors that can make a person more likely to develop Achilles tendinitis:

• Tight calf muscles. Calf muscle tightness puts extra stress on the Achilles tendon, especially where it inserts into the heel bone ^[5].
• A sudden increase in the amount or intensity of exercise activity. For example, increasing the distance you run every day by a few miles without giving your body a chance to adjust to the new distance may cause irritation and inflammation ^[5].
• A change in shoewear, which can also lead to increased strain on the Achilles tendon ^[5].

What are shin splints?

Shin splints happen when you’ve put too much stress on your leg ^[6].

You’ll have pain and tenderness along the front of your lower leg (shin) ^[6].

More on shin splints

You’re more likely to get shin splints if:

• you have started exercising after not being active for some time ^[6].
• you run or jump on hard surfaces ^[6].
• you do not have a good running technique ^[6].

What is a stress fracture?

A stress fracture is a small crack in a bone, or severe bruising within a bone ^[7].

Most stress fractures are caused by overuse and repetitive activity; they are common in runners and athletes who participate in running-intensive sports, such as soccer and basketball ^[7].

AAOS OrthoInfo advises: “See your doctor or provider as soon as possible if you think that you have a bone stress injury. Ignoring the pain will lead to worse injury, and you may take longer to heal.” ^[7]

More on stress fractures

The weightbearing bones of the foot and lower leg are especially vulnerable to stress fractures because of the repetitive forces they must absorb during activities like walking, running, and jumping ^[7].

The pain usually develops gradually and worsens during weightbearing activity ^[7].

Other symptoms may include:

• Pain that goes away during rest. AAOS OrthoInfo describes this as early on, when discomfort may occur only at the end of activity and for a short time after ^[7].
• Pain that is associated with physical activities throughout the day ^[7].
• Swelling on the top of the foot or on the outside of the ankle ^[7].
• Tenderness when pressure is applied to the area directly over the injured bone ^[7].
• Possible bruising ^[7].

What about shoes and training?

Old or worn-out running shoes may lose their ability to absorb shock and can lead to injury ^[7].

Running shoes need to be replaced on a regular basis ^[8].

More on warming up, cooling down and varying activities

AAOS OrthoInfo advises:

• Warm up to prepare for exercise, even before stretching ^[1].
• Make cooling down the final phase of your exercise routine ^[1].
• Vary your activities to help avoid overstressing one area of your body. For example, alternate a high-impact sport like running with lower-impact sports like swimming or cycling ^[7].

When is urgent help needed?

The list below covers the signs that should not wait for a routine appointment.

What should I do next?

If pain is not settling, or you are unsure what is causing it, an assessment is a sensible next step. The assessment brings together the patient’s story, an examination and any tests that help, so that the patient and the surgeon can decide together. It looks at the structure involved, the patient as a whole person and the goal they want to return to. An appointment supports an informed decision. It is not a commitment to surgery.

• Read about the Knee Hub.
• Read about ankle sprains.
• Read about Achilles tendinitis.
• Read about sports injuries.

References

1. AAOS OrthoInfo. Sprains, Strains & Other Soft-Tissue Injuries. https://www.orthoinfo.org/diseases–conditions/sprains-strains-and-other-soft-tissue-injuries (accessed 5 October 2026).
2. AAOS OrthoInfo. Patellofemoral Pain Syndrome. https://www.orthoinfo.org/diseases–conditions/patellofemoral-pain-syndrome (accessed 5 October 2026).
3. AAOS OrthoInfo. Sprained Ankle. https://www.orthoinfo.org/diseases–conditions/sprained-ankle (accessed 5 October 2026).
4. NHS. Plantar fasciitis. https://www.nhs.uk/conditions/plantar-fasciitis/ (accessed 5 October 2026).
5. AAOS OrthoInfo. Achilles Tendinitis. https://www.orthoinfo.org/diseases–conditions/achilles-tendinitis (accessed 5 October 2026).
6. NHS. Shin splints. https://www.nhs.uk/conditions/shin-splints/ (accessed 5 October 2026).
7. AAOS OrthoInfo. Stress Fractures of the Foot and Ankle. https://www.orthoinfo.org/diseases–conditions/stress-fractures-of-the-foot-and-ankle (accessed 5 October 2026).
8. AAOS OrthoInfo. Athletic Shoes. https://www.orthoinfo.org/staying-healthy/athletic-shoes (accessed 5 October 2026).