Foot training reduces risk of running-related injury by a factor of two and a half

In older people, the probability of falling was reduced by a factor of 7 in a study conducted at the University of São Paulo. Constant use of rigid or reinforced footwear is the main enemy of healthy feet, according to the researchers.

By José Tadeu Arantes  |  Agência FAPESP – The human body has various natural shock absorbers, and the feet are perhaps the most important. They support all our weight when we move or stand still. To perform these roles, each foot has an extremely complex structure, comprising 25 intrinsic muscles (fully contained within the foot), 10 extrinsic muscles (attached to the leg), 33 joints, and 108 ligaments.

The problem is that in an urban and increasingly artificial context, many people never walk in their bare feet, and all of us are egged on by advertising to wear shoes strengthened by a welter of rigid structures, including shock absorbers, except these are outside our body.

“All structures in the feet eventually atrophy if you wear these types of shoe for long periods. It’s as if you wore a neck brace all day long to protect you from headaches as you continuously look at a screen. Before long, your neck muscles would lose mass, force and functionality,” said Isabel Sacco, who heads the Human Movement and Posture Biomechanics Laboratory (LABIMPH) at the University of São Paulo’s Medical School (FM-USP) in Brazil.

Sacco is also principal investigator for the Thematic Project “Biomechanical and functional aspects of the musculoskeletal system of runners: chronic effects of therapeutic exercise and aging”, supported by FAPESP. Researchers at USP and three other institutions – the Federal University of the ABC (UFABC), also in Brazil, the University of Amsterdam (UvA) in the Netherlands, and Rizzoli Orthopedic Institute (IOR) in Italy – are also participating in the project.

“We’ve published research findings in several leading scientific journals. An article I’d like to highlight is ‘Foot core training to prevent running-related injuries: A survival analysis of a single-blind, randomized controlled trial’, published in The American Journal of Sports Medicine. This article is based on two PhD research projects linked to our Thematic Project. It shows that simple foot training reduces the risk of injury for recreational runners by a factor of 2.5,” Sacco said.

The risk of injury is critical because it affects both professional athletes and ordinary citizens. Running does not require any equipment apart from footwear and clothing and has become a widespread and democratic type of exercise. People of all kinds are runners, which is great, but the prevalence of injury is very high: as many as 79% of runners may experience injuries of some kind in any given year.

“The solution isn’t to give up running but to take preventive measures that reduce or at least delay the risk of injury. Stretching doesn’t work. It’s very important to maintaining the health of the skeletomuscular system, but not to preventing injury. Online guidance and handbooks that can educate runners on preventive strategies, as well as specific physical conditioning, are also ineffective. Injury is multifactorial, and footwear or special warming-up exercises won’t solve the problem,” Sacco said.

The main risk factor for injury is previous injury, she explained. This is because the body has to compensate in various ways in order to protect the injured region, and this can make it vulnerable to fresh injuries.

“What we discovered in our study was that the runner’s best defense against injury is improving the skeletomuscular structure of the feet to achieve gains in strength and functionality,” Sacco said. “We worked with a contingent of 120 recreational runners. They were divided randomly into two groups, one of which combined running and stretching exercises adopted as a placebo, while the other half combined running with foot training. After eight weeks, the number of injuries in the ‘training group’ was found to be 2.42 times lower than in the ‘placebo group’. MRI scans showed that foot muscle mass had increased in the subjects who received foot training.”

The improvement in foot health not only helped reduce the incidence of injury, or delay its occurrence but also modified running biomechanics by increasing vertical impulse capacity during push-off. 

“The bottom-up training strategy we developed was a paradigm shift in the field of rehabilitation and prevention for runners. Several schools adopt a top-down strategy, which is the opposite, prioritizing the trunk and hip muscles and neglecting the importance of the most distal extremities of the lower limbs,” Sacco said.

What is good for people who get plenty of exercise can be better still for sedentary people. “It’s a well-known fact that training the foot muscles, and specifically the big toe muscle, reduces the risk of falling by a factor of 7 in the elderly,” she noted.

The exercises in the foot training program can be done at home, with the aid of software developed by LABIMPH (visit: soped.com.br/). 

Besides specific exercises for the feet, the simplest and most natural way to strengthen the feet is to go about barefoot whenever possible. Minimalist or barefoot shoes are an alternative for walking in a street or even at home on cooler days. They are inexpensive and allow the feet some movement while walking. “In another study by our group, we showed that people with knee pain due to osteoarthritis experienced a 62% improvement after wearing barefoot shoes for a period,” Sacco said.

The article “Foot core training to prevent running-related injuries: A survival analysis of a single-blind, randomized controlled trial” is at: journals.sagepub.com/doi/10.1177/0363546520969205.