A long strip on the inner edge: shin splints, the commonest cause in runnersStrong evidence
Shin splints, or medial tibial stress syndrome, hurt along the inner border of the shin bone (the tibia), during and after exercise, and the strip is tender to touch, the American Academy of Orthopaedic Surgeons (AAOS) says. Runners have the highest risk, dancers and military recruits are often diagnosed too, and it usually follows a sudden change in how often, how long or how hard you train, such as adding hills. The NHS says it is more likely when you start exercising after a spell of inactivity, run or jump on hard surfaces, or don't have a good running technique.
It affects 5% to 35% of runners. In a review of 10 studies, women, people who had it before, newer runners, people using orthotics, a higher body mass index (BMI) and a bigger drop of the arch went with it. It can be diagnosed reliably from the story and an examination: two clinicians agreed 96% of the time in 46 athletes, and 74% of those athletes had shin splints, often alongside another lower leg injury.
Sources 1, 2, 3, 4
One spot on the bone: a stress fractureStrong evidence
A stress fracture is a small crack in a bone from overuse. Health New Zealand says the pain is often in one spot you can point to with a fingertip, gets worse with activity, and can become a constant dull ache even at night, then sharp when you put weight on it. The AAOS says bone stress injuries often appear 3 to 4 weeks after starting a new routine or season.
Where it is matters. In pooled studies of athletes, a stress fracture of the inner back edge of the shin bone took a mean of 44 days to return to sport, and one of the outer leg bone (the fibula) 56 days; more than 90% returned. The front of the shin bone is different: those fractures took longer, had more complications, and are considered for surgery if still painful after 3 to 6 months, though the studies are small.
Sources 5, 6, 7, 8, 9
Tightness that builds in every run: exertional compartment syndromeStrong evidence
The muscles of the lower leg sit in compartments wrapped in tough tissue. In exertional (chronic) compartment syndrome, pain or cramping comes on during exercise and goes away when you stop, sometimes with numbness, a foot that slaps down or a bulging muscle, the AAOS says, adding that compartment syndrome most often affects the front compartment of the lower leg. The NHS says the chronic form often doesn't need treatment, and asks you to see a GP if you keep getting pain, numbness or swelling when you exercise. Our exertional compartment syndrome guide covers it in full.
Sources 10, 11
After an injury: acute compartment syndrome is an emergencyStrong evidence
Acute compartment syndrome is a build-up of pressure inside a muscle, usually after an injury or under a bandage or cast that is too tight. The NHS lists severe pain in a muscle that may be worse when stretching it, swelling, numbness, weakness or pins and needles, and tightness or difficulty moving, and says it needs surgery as soon as possible. Surgeons' standards name pain far worse than the injury explains, and pain when the muscles are stretched, as the key signs; the AAOS adds that numbness or paralysis are late signs.
After an injury, a leg that is twisted or bent, a bone through the skin or signs of shock need 999 or A&E, and a leg that is very painful, very swollen or hurts to put weight on needs NHS 111, the NHS says.
Sources 10, 12, 11, 13
The muscles at the front, nerves and the backEmerging evidence
The muscles at the front of the shin lift the foot. Problems with them and their tendon are uncommon: a review says tendon problems of the tibialis anterior, the main one, are described only in case reports and small series. A burning, tingling or numb patch on the outer lower leg and top of the foot can be a squeezed skin nerve (the superficial fibular nerve), which a review says can be missed. And NHS inform says lower leg pain can come from the back, even without back pain, described as pins and needles, or sharp, hot or burning pain.
Sources 14, 15, 16
Children, infections, clots and other causesStrong evidence
Growing pains are common in children aged 3 to 12: aching in both legs in the evening or at night, gone by the morning. The NHS asks for a GP if the pain is in one leg, in the morning or when walking, makes them limp, is in one joint, or comes with a rash, swelling, unusual bruising, a high temperature or weight loss.
Cellulitis, a skin infection, makes the skin painful, hot and swollen and, on the legs, is usually on the lower legs. A blood clot causes throbbing pain and swelling in one leg, usually the calf or thigh. An ache on walking that goes after a few minutes' rest can be narrowed leg arteries. Bone pain that is worse at night, or a lump, needs a GP: rarely, it is a bone tumour.
Sources 17, 18, 19, 20, 21
When a scan or test helpsStrong evidence
Shin splints are diagnosed from the story and an examination, and the NHS says the same. If they aren't responding to treatment, a bone scan or a magnetic resonance imaging (MRI) scan will often show a stress fracture, the AAOS says.
For a suspected stress fracture, an early X-ray may look normal because bone swelling doesn't show on it; an MRI shows the swelling, and a bone density scan is considered if there are risk factors for weak bones or the injury came with light activity. Exertional compartment syndrome is confirmed by measuring the pressure in the muscles before and after exercise. A swollen, throbbing leg needs an ultrasound scan, which the NHS says should happen within 24 hours if a doctor thinks it's a clot.
Sources 4, 2, 1, 6, 10, 19
How it usually goesEmerging evidence
The NHS says shin splints usually get better within a few weeks. Athletes referred to sports medicine took longer: in a Dutch trial, a mean of 102 to 118 days to complete a graded return to 18 minutes of hard running, and 60 to 92 days in a shockwave study. People seen in specialist clinics are likely to be the harder cases.
Stress fractures usually take 6 to 8 weeks to heal, Health New Zealand says; the AAOS says at least 3 weeks, and up to 3 months or longer when more severe; and the front of the shin bone takes longer. Growing pains come and go over months, even years. No one can promise a date.
Sources 2, 22, 23, 5, 6, 7, 17
