Want to avoid running overuse injuries? Don’t lean forward so much, says CU Denver study

Press release:

The ubiquitous overuse injuries that nag runners may stem from an unlikely culprit: how far you lean forward.

Trunk flexion, the angle at which a runner bends forward from the hip, can range wildly–runners have self-reported angles of approximately -2 degrees to upward of 25. A new study from the University of Colorado Denver (CU Denver) found that greater trunk flexion has significant impact on stride length, joint movements, and ground reaction forces. How you lean may be one of the contributors to your knee pain, medial tibial stress syndrome, or back pain.

“This was a pet peeve turned into a study,” said Anna Warrener, PhD, lead author and assistant professor of anthropology at CU Denver. Warrener worked on the initial research during her postdoc fellowship with Daniel Liberman, PhD, in the Department of Human Evolutionary Biology at Harvard University. “When [Lieberman] was out preparing for his marathons, he noticed other people leaning too far forward as they ran, which had so many implications for their lower limbs. Our study was built to find out what they were.”

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Icing muscle injuries may delay recovery

Press release from Kobe University:

A study using a mouse model of eccentric contraction (*1) has revealed that icing injured muscles delays muscle regeneration. The discovery was made by a research group including Associate Professor ARAKAWA Takamitsu and then PhD. Student KAWASHIMA Masato from Kobe University’s Graduate School of Health Sciences, and Chiba Institute of Technology’s Associate Professor KAWANISHI Noriaki et al. In addition, the researchers illuminated that this phenomenon may be related to pro-inflammatory macrophages’ (*2, 3, 4) ability to infiltrate damaged cells. This research raises questions as to whether or not severe muscle injuries (such as torn muscles) should be iced.

These research results were published online as one of the Journal of Applied Physiology‘s Articles in Press on March 25, 2021.

Main points

  • The research results revealed that applying an ice pack to a severe muscle injury resulting from eccentric contraction may prolong the time it takes to heal.
  • The cause of this phenomenon is that icing delays the arrival of pro-inflammatory macrophages, which are responsible for the phagocytosis (*5), or removal, of damaged tissue. Furthermore, this makes difficult for the macrophages to sufficiently infiltrate the damaged muscle cells.

Research Background

Skeletal muscle injuries encompass a range of damage to muscles; from a microcellular level to a severe level. These injuries include not only those that happen during sports or schools’ physical education lessons but also external injuries that occur as a result of accidents and disasters.

‘RICE treatment’ is a common approach for skeletal muscle injuries, regardless of the extent of the injury. This acronym stands for Rest, Ice, Compression and Elevation and is often used in physical education, sports and even medicine. Ice is commonly applied regardless of the type of muscle injury, yet little is known about the long-term effects of icing.

Ice is used to suppress inflammation, however, inflammation in response to tissue injury is one of the body’s healing mechanisms. This has come to be understood as a vital response for tissue regeneration. In other words, suppressing inflammation with ice may also inhibit the body’s attempt to repair itself.

Experiments investigating the effect of icing muscles after injury have produced conflicting results. Some have reported that it delays muscle regeneration while others have stated that it doesn’t inhibit this process. However, none of the research up until now has investigated the effects of icing using an injury model that mimics common sports injuries caused by muscle contraction.

Using a mouse model of eccentric contraction injury, the current research team decided to observe the effects of post-injury icing. In this mouse model, injuries were induced to resemble severe torn muscles.

Research Methodology and Results

Eccentric contraction was induced by electrically stimulating the leg muscles of the mice and then exerting a stronger force during this stimulation to make the leg muscles move in the opposite direction. After this, the muscles were harvested. Icing was performed by placing polyurethane bags of ice on top of the skin over three 30 minute sessions per day, with each session being 2 hours apart. This was continued until two days after the injury. The icing was based on the usual clinically recommended method.

The researchers investigated the regenerated skeletal muscle two weeks after injury, comparing the icing group with the non-icing group. A significantly higher percentage of smaller regenerated muscle fibers were found in cross-sections from the icing group, with a greater number of medium to large fibers in the non-icing group (Figure 1). In other words, this revealed that skeletal muscle regeneration may be delayed as a result of icing.

Next, the researchers periodically took samples of muscle from the icing and non-icing groups of animals in order to investigate what was happening in the regeneration process up until this point.

In the regeneration process, inflammatory cells gather at the site of the injury, remove the debris from the damaged muscle and then begin to build new muscle. However, the results revealed that it is harder for inflammatory cells to enter the injured muscle cells if ice is applied (Figure 2).

Macrophages are typical of the inflammatory cells that enter the injured muscle. These consist of pro-inflammatory macrophages, which phagocyte damaged tissue thus causing inflammation, and anti-inflammatory macrophages (*6), which suppress the inflammatory reaction and promote repair. It is thought that pro-inflammatory macrophages change their characteristics, becoming anti-inflammatory. The results of this research team’s experiments showed that icing delays the arrival of pro-inflammatory macrophages at the site of the injury (Figure 3).

These results indicate the possibility that macrophages are unable to sufficiently phagocyte the damaged muscle when ice is applied after severe muscle injuries caused by eccentric contraction, consequently delaying the formation of new muscle cells.

Comment from Associate Professor Arakawa

In sports, the mantra of immediately applying ice to an injury is commonplace, regardless of the injury’s severity. However, the mechanism that we illuminated through this research suggests that not icing a severe muscle injury may lead to faster recovery. The idea of immediately cooling any type of injury is also entrenched in schools’ physical education classes. I hope that in the future, the alternative option of speeding up recovery by not cooling severe muscle injuries will become known.

However, even though icing may disrupt the recovery process for severe muscle injuries, there is no denying the possibility that there are degrees of mild muscle injuries that can be iced. The next issue is to work out where to draw the line. We are now in the middle of investigating what effect icing has on slight muscle injuries.

Next, we will continue to investigate how icing should be carried out according to the extent of the muscle injury. We aim to contribute guidelines that will enable people in sports and clinical rehabilitation to make accurate judgements about whether or not to ice an injury.

RunEASI wearable enables runners to train and rehabilitate more efficiently

The wearable is worn around the waist.

Press Release:

Being able to exercise without pain or injury: it’s every athlete’s dream as well as the goal of RunEASI, a new spin-off of KU Leuven. RunEASI’s wearable measures the impact experienced by runners and provides scientific feedback that can help them avoid and recover from injuries. The spin-off is supported by the Gemma Frisius Fund and the Freshmen investment fund.

Runners typically use a heart rate monitor, but this device does not offer insight into how the body responds to the impact caused by the feet landing on the ground. And yet, this impact is precisely what determines the risk of injuries. RunEASI – which originated from a collaboration between movement and computer scientists at KU Leuven – has therefore developed a wearable application that does assess these important parameters.

This is achieved using a sensor that is attached to the lower back with a belt and is connected to an app. The sensors measures the impact on the body while running and detects any movement compensations that may occur. The app provides feedback to improve the running pattern. RunEASI is the first application that can perform such an analysis and intervention in a scientifically validated and efficient way. The application will be available on the market as of mid-February 2021.

Stability, symmetry, impact

“We are trying to establish the link between the way in which someone runs, the associated impact loads, and the risk of injuries,” says Professor Benedicte Vanwanseele from the Human Movement Biomechanics unit at KU Leuven. “Three parameters are key to this: stability, symmetry, and impact.”

“Research has shown that trunk instability increases with a runner’s fatigue level. When this is combined with high impact loads, this creates a compensatory pattern that increases the risk of overuse injuries. Symmetry shows whether the impact is equally divided between left and right: after an injury, for instance, a runner may favour one leg without realising it. Last, but not least, the impact parameter shows how the body responds to the shocks that occur when the foot strikes the ground.”

“Our tool intervenes when the data show that the runner has a harmful running pattern,” says computer science professor Jesse Davis. “AI allows us to analyse when the body is exposed to the most severe impacts. This can depend on the surface, the pace, the duration of the training, the runner’s fatigue, and other factors. On the basis of this analysis, coaches and physiotherapists can proactively adjust the runners’ training.”

More insight and better support

“With RunEASI we want to help runners, whether it be professional or recreational ones, to achieve their goals with less risk of injury,” explain co-founders Kurt Schütte (CEO) and Tim Op De Beéck (CTO). “The way our sensor is attached is unique and was developed in cooperation with the orthopaedic experts at Steunzoolpunt. It enables us to measure our new movement metrics very efficiently and accurately. Physiotherapists can use this scientific analysis to better assess when someone is ready to resume training after an injury.”

“We strongly believe in digital tools that improve a person’s quality of life, and this ambition is also reflected in RunEASI,” says Steven Spittaels of the Freshmen investment fund. “It’s an application that, thanks to its scientific feedback, can be of great added value to runners and professional healthcare providers. Athletes obviously want to know how to stay injury free and we want to support RunEASI to help them achieve this.”

“We are extremely grateful for the belief and financial support of the Gemma Frisius Fund and Freshmen Fund,” responds CEO Kurt Schütte. “With their support, we can fulfil our mission and ambition to make the world run better.”

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More information

The RunEASI wearable can be pre-ordered and will be available as of mid-February 2021. Check the website for further information: runeasi.ai