All runners, whether you are a competing athlete or a weekend enthusiast, should be aware of the effects of footwear on performance and foot and ankle injury, and steps to prevent injury and reduce the rate of re-injury. Injury rates differ significantly across athletes, but importantly, some types of injuries are preventable. This summary provides patients with a short background on ankle and foot biomechanics, appropriate footware and injury prevention strategies.
Foot and Ankle Biomechanics
Anatomy & physiology
The foot and ankle form a complex system which consists of 28 bones, 33 joints, 112 ligaments, controlled by 13 extrinsic (superficial) and 21 intrinsic (deep) muscles. The foot is subdivided into the rearfoot (towards heel), midfoot, and forefoot (towards toes). The foot and ankle is as a rigid structure for weight bearing and as a flexible structure to conform to uneven terrain. It functions to support body weight, provide balance, shock absorption, transfers forces through the ground and compensates for body malalignment.
Ranges of motion
Compared to other joints in the body, like the shoulder, the foot and ankle has relatively little range of movement. This limited range is a trade-off for its function as a rigid, supportive and weight-bearing structure. The foot and ankle has 4 main ranges of motion: flexion, extension, eversion (supination), and inversion (pronation). However, throughout movement, there is relative multi-axial movement between each of the joints in attempt to constantly maintain optimal arthrokinetics (i.e., joint movement for balance, muscular control, and proprioception etc.). Proprioception is guided by receptors in the body (e.g., skin, muscles, joints) that connect with the brain through the nervous system so that even without sight, a person knows what their body is doing.
Kinematic chains are used to describe the relationships between body segments and joints during movement. There are closed (limb is fixed in space and cannot move) and open (limb is free to move in space) kinematic chains. The kinematic chain is one way we can explain how low back, hip and knee injuries can impact on foot and ankle biomechanics. For instance, an internally rotated hip, whether due to an structural or functional cause, can cause the leg to internally rotate which then causes the foot to overpronate (pictured below). In gait, the transition of foot pronation to supination is an important function that assists in adapting to uneven terrain and acting as a rigid lever during push off. Repeated pronation sprains cause scar tissue to form about the outer part of the ankle joint, which reduces its range of motion, and therefore its ability to adapt to uneven terrain.
Interestingly, closed kinetic chain exercises appear to be more effective at improving of dynamic balance ability than open kinetic chain exercise within a 6-week training period.
Arches of the foot
The foot has 3 normal arches: a medial longitudinal arch (MLA), lateral longitudinal arch (LLA) and an anterior transverse arch (ATA). The arches of the foot function to absorb force, provide a base of support, and act as rigid levers during gait (i.e., walking pattern) propulsion. A decrease or increase in the arches can change the biomechanics of the foot and ankle. You may have heard of ‘flat feet’? This is called pes planus and is due to increased laxity (stretch and weakness) of the spring ligament (that spans across the MLA), and the plantar aponeurosis (i.e., connective tissue spanning across the sole of the foot). A high arch is called pes cavus and is less common than pes planus.
Ankle power and forces
Ankle power varies when the major ankle muscles are either absorbing or generative power during gait. The maximum ankle joint power is generated at around 50% of the gait cycle when the forefoot rocks off the ground corresponding to the power generated by the plantarflexor muscles (i.e., calf muscles) to propel the body forward towards toe-off.
The ankle joint bears a force of approximately 5 times body weight during stance in normal walking, and up to 13 times body weight during activities such as running. It would be therefore sensible to ensure you are taking all preventative measures to avoid injury.
Foot and Ankle Injuries
Running has one of the largest participation rates. Statistics from the Australian Sports Commission’s 2006 survey showed an estimated 1,224,100 Australians aged 15 years and older participated in running in the 12 months prior to being surveyed. Up to 70% of recreational and competitive runners sustain overuse injuries during any 12-month period. 42% of all running injuries are to the knee, followed by 17% to the foot/ankle, 13% to the lower leg and 11% to the hip/pelvis.
Types of injuries
The most common types of foot and ankle injuries in runners include:
- Ankle sprains: when this type of ankle sprain happens, the outer, or lateral, ligaments are stretched too much. The anterior talofibular ligament is one of the most commonly involved ligaments in this type of sprain. Approximately 70-85% of ankle sprains are pronation injuries.
- Achilles tendinopathy: causes pain and stiffness of the Achilles tendon that joins your heel bone to your calf muscles. Approximately 6 in 100 inactive people develop Achilles tendinopathy at some point in their lifetime. There is no universally accepted model for the development of achilles tendinopathy, but overuse of the Achilles tendon a common cause. Other causes include poor footwear and running technique, training on hard or uneven surfaces, and pre-existing achilles conditions.
- Plantar fasciosis: pain and inflammation of the plantar fascia, a thick, fibrous band of connective tissue on the bottom surface of the calcaneus (heel bone) and extending along the sole of the foot towards the toes. There are 2 types of injuries: traction (i.e., repeated over-stretching due to faulty biomechanics, such as toe running) or compression (i.e., traumatic like landing on a sharp object) injuries.
- Stress fracture: tiny cracks develop in the bones of the foot in the case of runners. They are caused by repetitive application of force, often by overuse (e.g., running, jumping), and develop over a period of time. The pain is quite distinctive getting worse as you do more weight bearing activity such as running.
Management & Preventative Stragergies
The management of your foot and ankle injury depends on the cause of your pain and dysfunction. Generally speaking, for acute (0-4 days) injuries, we use the RICER protocol: Rest, Ice, Compression, Elevation, Referral. Analgesic and nonsteroidal anti-inflammatory drugs (NSAID) may provide symptomatic relief from initial pain and inflammation, but are not indicated for long-term use.
- Ankle sprains: the literature supports the use of a semi-rigid ankle brace for grade 1-3 sprains in the acute and subacute (5-14 days) phase. Soft-tissue massage and joint mobilisations may also decrease stiffness and improve range of motion. Exercises might begin non-weight-bearing using joint range of motion and isometric strengthening techniques. As pain and swelling subsides, exercises might include light weight-bearing, concentric and then resisted exercises. Graded neuromuscular and balance training and analysing faulty biomechanics have also shown to be effective management and preventative strategies.
- Achilles tendinopathy: the evidence suggests that eccentric (stretching and strengthening under load) exercises of the calf muscles is an effective management strategy. Other strategies that have not been substantiated in the literature include orthotic treatment (orthoses, footwear correction).
- Plantar fasciosis: the evidence for management options is unclear, but generally they include fascial and muscle eccentric stretching, soft-tissue massage and weight loss initially. If persistent, there is weak evidence that corticosteroid, dextrose (prolotherapy) or botulinum toxin injections and anterior night splints help to reduce pain and disability.
- Stress fracture: initially, rest of the fracture site is indicated with a focus on maintaining general aerobic fitness, non-weight-bearing physical therapy (e.g., pool running and cycling), and oral analgesics (other than NSAID, which slow bone healing). Weight-bearing as tolerated and ambulation modification if needed is also required, yet running should be avoided. Once symptoms begin to decrease at approximately 2-3 weeks, rehabilitation should focus on muscular endurance training, core and pelvic girdle stability, balance/proprioception training, flexibility, and gait retraining when appropriate. At week 8, the fractures should have fully resolved and the patient should return to normal activities.
Footwear in Runners
With so many different types of footwear on the market, it can be difficult to know which shoe is most appropriate for your body type, level of fitness and back-pocket! Footwear is totally subjective and it is always best to seek advice from a specialist or at least have your gait and feet objectively measured in a footwear store to find out what fits best for you.
Appropriate footwear advice and the use of energy-absorbing materials to help dissipate shock are preferred in runners of all skill levels. Running shoes for pronated runners should control the excessive motion. The shoes should be board-lasted, straight-lasted, have a stable heel counter, extra medial support, and a wider flare than the shoes for the cavus foot. For these athletes a slip-lasted, curve-lasted shoe with softer ethylene vinyl acetate and a narrow flare is appropriate. Orthotic devices are useful in selected runners with demonstrated biomechanical abnormalities that contribute to the injury.
Minimalist footwear in running
The effects of running in minimalist shoes is a topic of interest for runners and for researchers. Running in minimalist shoes can improve running performance by making athletes run with a more plantar-flexed ankle at initial contact and adopt a better forefoot pattern, increase stride rate, reduce stride length, increase ankle plantar-flexor moments and decrease knee extensor moments.
A systematic review with meta-analysis found significant moderate beneficial effect on running performance for training in minimalist shoes compared to conventional shoes. Significant small beneficial effects on running performance for light shoes and barefoot (compared with heavy (shod) shoes) was also found. However, it is important to note that the improvement in running performance in both groups, regardless of shoe type, may have been due to compliance with training over the 10-week study period and/or familiarity with testing procedures.
There is a lot of contention surrounding barefoot running compared to running in footwear. Barefoot running is not for everyone, particularly in novice runners. A systematic review found that barefoot running or running in minimalist shoes may require lower utilisation of oxygen than in shod footwear. Theoretically, the lower oxygen cost may improve long distance running performance. However, more than half of the runners in the included studies had previous barefoot experience and the findings may not apply to athletes who use shod runners or novice runners who are undergoing the transition to barefoot running. In these groups, there may be an increased risk of injury with barefoot running.
For more information on foot and ankle injuries, please visit our website:
- Ankle and Foot Pain Overview
- Lateral Ankle Sprain
- Medial Ankle Sprain
- Bruised Heel
- Broken Heel Bone (Calcaneal Fracture)
- Athletes Foot
- Heel Spurs
- Stress Fractures in the Ankle and Foot
- Injury Prevention, Ankle Biomechanics & Footwear in Runners
- Tissue Injury and Factors Affecting Recovery
- How Can Chiropractic Help After a Sports Injury?