What are “Shin Splints”?
By Doug James – Physiotherapist and Podiatrist, intraining Running Injury Clinic
Shin pain is a common complaint seen at the intraining running injury clinic. When the injured runner is quizzed on what they think is wrong, they confidently say “Shin Splints”, and then quickly admit they have no idea what that means.
“Shin Splits” is a wide-ranging term for exercise-induced lower leg pain. It is very general in nature as the lower leg contains a number of different structures that can be responsible for this pain. The most common form of shin pain in runners is called “Medial Tibial Stress Syndrome” or MTSS.
Medial Tibial Stress Syndrome (MTSS)
MTSS involves pain and injury to the medial (i.e., left side of the right shin and vice versa) part of the main shin bone (the tibia) as a response to stress (usually some sort of impact exercise). This injury is a continuum where the severity can progress or regress based on the healing ability of the athlete, and the amount of stress the leg is exposed to.
Shin Bone Anatomy
Positioned along the outside of the tibia bone is a thin layer of tissue called periosteum which helps muscles attach to it. There are a number of muscles that attach to it, most notably being your calf muscle, which uses the tibia as leverage to provide the main forwards’ force when running as well as shock absorption on impact.
In the early stages of MTSS, the periosteum can become inflamed from the tension created by the deeper calf muscle – the Soleus – when contracting during movement. This can be felt as mild discomfort and is unpleasant to touch. With adequate healing time, pain management (ice packs, anti-inflammatory medication) and rest this will usually calm down in a few days. It may be uncomfortable to exercise on initially but will usually “warm up” within 10-15 minutes and be unnoticeable until the leg has cooled down again.
The more advanced and severe stages of MTSS more directly affect the tibia. This bone contains a hard outer layer (cortex) with soft marrow within it. Running subjects the tibia to different forces – compression along with flexion and twisting as the bone absorbs shock both directly and via its muscle attachments. A healthy bone will have a capacity to resist these forces and with regular, gradually increasing exposure, this capacity can increase too via the body’s repair process. Where training load has exceeded the body’s ability to repair that stress, the bone marrow can become bruised and swelling accumulates within it –known as a stress reaction.
Stress Reaction Stage
This moderate stage of the injury tends to take longer to warm up and may become sore again during longer or higher intensity sessions. By reviewing a thorough history and performing some clinic testing, a Sports Podiatrist or Physio should be able to determine if the injury is in this stage. If in doubt, an MRI (not an X-ray or Ultrasound scan) can be used to detect the level of severity.
Reduced loading for a short period of time is usually recommended to allow the body a chance to repair the tibia properly. When the body repairs the tibia, it strips away part of the damaged bone which in turn makes it temporarily weaker and more prone to worse damage during this time. If training intensity and/or volume is resumed at a too great intensity and/or volume this can lead to the final stage of MTSS – a stress fracture.
Stress Fracture Phase
The final stage of MTSS involves damage to the cortical (outer) layer of bone. When a hairline fracture occurs within the tibia bone, weight-bearing exercising is usually consistently painful and swiftly becomes worse. The shin may also be painful when walking and at rest. Unfortunately, tibial stress fractures require complete rest from running and other impact activities. Recovery usually takes at least 8 weeks or more depending on the part of the bone affected. Upon return to training, load management is imperative and training in the early weeks needs to be resumed at a conservative level to prevent reoccurrence.
MTSS Risk Factors
The amount of training stress required to trigger MTSS varies across athletes. Where some runners can comfortably run 200km in a week, others may develop MTSS doing just 10% of that. The key is how well-conditioned each runner is. If an athlete has a long history of consistent running with minimal injuries, they generally will have stronger bones and more resilient muscles and periosteum. This strength and resilience provide protection against MTSS if the training load increases within a reasonable amount – approximately 10-20% of the previous week’s time or distance, though intensity also needs to be considered. Recovery is also critical for avoiding MTSS. This is not only periods of rest between running sessions, but also includes good nutrition (including calcium and Vitamin D), and 7-9 hours of sleep each night. It is important that footwear suits that athlete’s foot type and be in good condition (ideally <800km old).
A potentially more serious shin injury that can develop in runners is Compartment Syndrome. This occurs when the amount of pressure within the muscle compartment (formed by the muscle sheath) significantly restricts or occludes the flow of blood within it resulting in pain, swelling, and often numbness and coldness in the shin and foot. Direct trauma can cause it, however significant sudden increases in training load (often seen in new Army and Police recruits) can increase the muscle size and/or amount of fluid within the sheath which persists for hours or days after exercises. Where symptoms (particularly nerve and circulation symptoms) persist, emergency surgery is needed to release the compartment pressure by creating an incision in the sheath. While this injury is relatively rare, it has shared risk factors with MTSS and may be avoided with a carefully considered approach to training and recovery.
How to treat Shin Splints
Shin pain has a number of contributing factors. How you run, along with how often and how far you train, and what shoes you wear while running can have an important influence on the development of shin injuries. The Podiatrists and Physiotherapists at the intraining running injury clinic are experts at addressing these aspects. They are experienced in the assessment and treatment of shin and running injuries and are able to help you manage and avoid these issues. If you’re currently dealing with shin pain, or are looking to start or increase your running training, book in to see one of the running experts at the intraining running injury clinic to ensure you’re on the road to pain-free running.
Doug James – Physiotherapist & Podiatrist
Doug James is a qualified physiotherapist and podiatrist with special interest in running and sports injuries. He combines the two treatment approaches to achieve successful outcomes for clients of all abilities from non-athletes through to elite athletes.
Bachelor of Podiatry (honours), Master of Physiotherapy Studies.
Doug has undertaken further training in dry needling, Pilates, and Rocktape and may incorporate these as necessary during treatment.
Doug is also a keen runner having completed the New York Marathon.