Tag Archives: running

Ditching the shoes: Minimalist trend or natural advantage?

The discussion of returning to minimalist ways, namely walking or running barefoot, is a question that rises in many circles, from new parents to elite runners. For example, parents are told to let children learn to walk barefoot, as studies have shown early use of footwear can lead to feet deformities and can alter natural gait, which is especially important when learning to walk. Likewise, many avid and elite runners have shown interest in barefoot running (or minimalist running shoes), as some are convinced that the forefront strike (FFS or also known as NRFS – non rear foot strike), more commonly used during barefoot running, lowers the loading rate on the foot and minimizes injuries from the repeated stress that occurs in the feet during running. 

Diagram illustrating four phases of foot contact with the ground for forefront strike and rear foot strike patterns
Forefront strike (top) and rear foot strike (bottom). Modified from Daniel E. Lieberman et al., Springer Nature 2010

In general, walking or running barefoot yields more frequent steps, a smaller stride length and a slower velocity (most noticeable while running). Barefoot running is thought to reduce some of the injuries many runners are prone to, such as shin splints, stress fractures or plantar fasciitis. Additionally, the stiff fit of modern shoes limits the width and spreading of feet in the natural walking or running motion. However, barefoot running also comes with a cost, with injuries in the achilles region more prevalent. 

A study in the Gait & Posture journal examined foot motion in children and found modern commercial footwear does have a large impact on gait, especially in regards to range of motions of different muscles and joints in the foot, likely due to the stiffness of shoes. More flexible shoes, similar to minimalist running shoes, were found to have a smaller impact on foot motion in reference to bare feet, but still had a significant difference in regards to the added support in the arch area. 

The common belief that barefoot motion lowers the impact on the body has been questioned by a recent research study from Southern Methodist University. The findings indicated that while running barefoot with a forefront strike, the feet strike the ground at a more pronounced angle which generates a longer contact time, thus decreasing the loading rate and allowing the muscles in the back of the feet and legs (especially the Achilles) to absorb some of the loading stress. When humans adapted to running in shoes, especially shoes with thick cushioning, the landing switched to a rear foot strike that allows the heel cushioning to absorb some of the loading stress, resulting in a fairly equal loading rate for both cases. The heel cushioning, with a flatter angle of contact, also allows for decreased impact time with the ground surface, which is why higher running speeds are achieved with footwear. 

barefoot person walking outdoors during the day
Photo by ‏🌸🙌 في عین الله on Unsplash

While the advice to encourage barefoot walking in young children certainly makes sense as they continue to grow and learn to control their bodies, the choice to use shoes or go barefoot for older children and adults remains an individual preference. There is no significant difference in the stresses the body experiences, but the footwear choice does influence the likelihood of certain, which is important for runners with past injuries to consider.

For more information, check out this extensive technical review of studies on barefoot vs. footwear mechanics or this video from Exercising Health comparing running shoes with minimalistic barefoot shoes.

Heads Up and Eyes Steady – The Optimized Mechanism for Human Running

In the insightful words of Bruce Springsteen, we as human beings were Born to Run. Humans have never been a sedentary species. The tendency to constantly relocate for survival purposes required skill in obtaining food efficiently, which heavily influenced early human evolution. Humans with optimal body mechanics for running ultimately held an advantage in hunting and gathering for food, and over time, the human body adapted to these survival requirements and developed a self-optimizing mechanism for running. This implies that initiating the act of running activates certain responses in the body to perform most efficiently.

Two aspects of the human body that the mechanism for running must account for, more so than other living species that depend on running for survival, is the bipedalism of humans and the disproportional size and weight of the head compared to other living species that run. For optimal locomotion, the head must remain stable while the body is in motion and experiencing the impacts of running not only to minimize the strain on the neck, but to allow for a steady gaze and safe navigation of the environment and potentially dangerous terrain. In order to achieve this, the human body has developed aspects within the mechanism for running that specifically protect against body pitching and head instability.

Plot title: Brain-to-Body Mass Ratio
X-axis: Body Mass (kg)
Y-axis: Brain Mass (kg)
where the ratio for humans is the largest compared to various other animals.
Image from Charlotte Swanson, Science World

The default mechanics of an individual’s natural stride minimize the shock through the body so that it may function as metabolically efficient as possible. This is true for most processes found in the universe; systems are constantly seeking a lower state of energy, and human beings are no different. Thus, as found in the research conducted by Michael A. Busa, Jongil Lim, Richard E. A. van Emmerik, and Joseph Hamill, the human body reacts to the external stimulus of running with a tendency toward an optimal stride frequency, which allows the head to be most stable during the motion.

Looking even further into the human body’s mechanism for running, a study was conducted by Andrew K. Yegian and Yanish Tucker investigating the involvement of neuromechanics. The researchers hypothesized that there was a neuromechanical connection between the biceps brachii and the superior (or upper) trapezius that served to provide stability for the head during running.

Biceps brachii highlighted in color on skeletal diagram.
Image from Wikipedia “Biceps Brcachii”
Sections of the trapezius muscle, upper or superior in orange, middle in red, and lower in fuchsia
Image from Wikipedia “Trapezius”

Although the activation of these two muscles is seemingly uncorrelated, the connection points on the shoulder are very close to once another and the line of action of both muscles is almost parallel. Both muscles are known to resist rotational impulses, and thus body pitching initiated by the significant weight of the head, during the foot’s contact with the ground during running.

In the study, the researchers observed human subject running on a treadmill and tracked muscle activity with electromyographic (EMG) sensors. They found the timing of muscle activation to be strongly coincident, and the magnitudes of both activation levels in both muscles were generally larger when mass was added to the runner’s head to further test the neuromechanical linkage. Due to the approximately parallel lines of action, the coincident forces from the biceps brachii and the superior trapezius, which act in opposite directions, directly support the stability of the scapula, which ultimately controls the stability of the head and upper body above the torso during running.

At this time, it is unknown whether the neuromechanical linkage between the biceps and the upper trapezius muscles to stabilize the head during running is direct or indirect, so further research is required to determine the mechanism that causes the muscle coordination.

For more general information about the biomechanics of running, visit this article found in Psysiopedia.

Work Smarter Not Harder!

We have all likely heard the saying, “Work smarter not harder.” While this is generally referenced in an academic setting, it is also very applicable in athletics! One of the benefits to being a runner is that it’s a sport people can participate in at any age and nearly anywhere. Unfortunately, however, anywhere from 65-80% of runners get injured in a given year. A large portion of these injuries are related to overuse.

Recovery

It’s a common misconception amongst runners that the harder you push during your runs, the faster you will be on race day. As a result, the majority or runners overdo their “easy” days. This leaves their legs fatigued and tired going into workouts and races. The majority of fitness is gained during a “workout” day, so overdoing easy days reduces your ability to push hard on workout days. To truly maximize their potential, an athlete must focus on their recovery. Recovery is a broad term that includes a variety of factors such as sleep quality, nutrition, and post run stretching and rehab exercises. Monitoring your heart rate is one way to manage your recovery, reduce overtraining, and limit bone stress injuries. 

Managing Heart Rate

Photograph of a smartwatch reading heart rate
Photo by Brooke Trossen

Heart rate monitors are used by runners to train smarter and ultimately race faster. Resting heart rate and heart rate recovery measurements are indications of how an athlete’s body is responding to stress and exercise long term. Heart rate measurements can be used to guide what the pace of a run should be. Heart rate measurements are commonly separated into five “zones.” On different days of the week and stages in a training cycle, a run should fall into the different zones. It may be beneficial for an athlete to also have a general idea of what their heart rate is at a given running pace. If their heart rate is more than 7 beats per minute above the usual rate, it may be a sign that the athlete has not fully recovered from their last training session and that they should continue with easy days until having another intense session. This is also important for runners since the weather conditions can greatly affect the difficulty of a run. Rather than having a goal pace for a given day, it is better to have a goal range of heart rates to make sure the run is best serving the athletes body. This will enable an athlete to get the appropriate effort in whether it is 70° and sunny or 30° with 20 mph winds.

Monitoring heart rate after exercise can also accurately indicate whether or not an athlete is fully recovered. It is important to note that your heart rate fluctuates, so it is more valuable to observe general trends than it is to overanalyze specific data points. A morning heart rate 5 beats per minute above your usual heart rate may be indicative that your body needs more rest or that you are getting sick. The image below shows a chart with ranges of resting heart rates depending on gender and age.

Chart of healthy resting heart rates for men and women with varying ages.
Photo by Jeremy on Agelessinvesting.com

Minimizing Bone Stress Injuries

Photograph of a stress reaction in the femur of a female runner
Photo by Brooke Trossen

Building a training plan with runs in a variety of zones will help limit overtraining and make the development of overuse injuries less likely. A bone stress injury (BSI) is defined as the inability of a bone to withstand repetitive loading. There are varying degrees of bone stress injuries from stress reactions to complete bone fracture. When performing repetitive motions such as running, micro-cracks form in your bone. These micro-cracks are actually healthy because loading your bones makes them stronger. In the process of remodeling, the micro-cracks are healed. Generally, additional remodeling units can be recruited in response to increase loads. The increase in remodeling units present, decreases the amount of bone mass. This results in a decrease in the ability for the bone to absorb energy and an increase in the number of cracks formed. When insufficient time is given for remodeling, the micro-cracks will begin to accumulate and stress reactions and fractures will form. A stress reaction in the right femur of a female runner is shown in the image above. The white highlights represent inflammation in the bone. 

Although overuse injuries are very common in runners, research shows that the use of heart rate monitors can help regulate recovery and positively influence training plans to limit overtraining. 

Ankle Sprains: An Epidemic in the World of Athletics

Have you ever been out running on a gorgeous fall day, only to have the run cut short by a painful misstep on a tree root covered by leaves? I have, and let me tell you – it’s awful! And even if you aren’t a runner, according to the Sports Medicine Research Manual, ankle sprains are a common, if not the most common, injury for sports involving lower body movements. Now, the solution to preventing this painful and annoying injury could be as simple as avoiding tree roots and uneven ground, but the real problem behind ankle sprains deals with the anatomy of the ankle.

The ankle is made up of many ligaments, bones, and muscles. However, when sprained, it is the ligaments that are mainly affected. Connecting bone to bone, ligaments are used to support and stabilize joints to prevent overextensions and other injuries. The weaker a ligament is, the easier it is to injure. There are three main lateral (outer) ligaments supporting the ankle joint that can become problematic: the anterior talofibular ligament, the calcaneofibular ligament and the posterior talofibular ligament. According to a study from Physiopedia, these lateral ligaments are weaker than those on the interior (medial) of the ankle, with the anterior talofibular ligament being the weakest.

An image depicting the various ligaments of the ankle, both lateral and medial.
Anatomy of the ankle, highlighting the lateral and medial ligaments

The next question that has to be asked is why are these ligaments so much weaker than other ones? The answer to this question is based on their physical make up. Ligaments are made of soft tissue that has various collagen fibers running parallel to each other throughout it. The more fibers there are, the more structure and rigidity there is. Think of the fibers as a rope: The rope can stretch to a certain point, but once it hits that point it will snap and break. But if you have a thicker rope (such as the medial ligaments), it becomes much harder to break.

The ligaments on the outer part of the ankle have fewer collagen fibers than those on the inside of the ankle. Thus, when the ankle is moved in an awkward position, it is more likely that the lateral ligaments will break.

Once you sprain your ankle, the focus turns to treatment. Treatment will differ slightly for every individual depending on the severity of the ankle sprain. The simplest way to treat a sprained ankle is to follow the RICE (Rest, Ice, Compression, Elevation) method. Other forms of treatment include taping the ankle or using a brace to restrict movement and to add support and extra stability. Wearing proper footwear is another way that one can prevent and help treat a sprained ankle, as certain shoes are specifically designed to help avoid such injuries. To prevent future ankle sprains, exercises are recommended to help strengthen and stabilize the joint and surrounding ligaments and muscles.

For more information on ankle anatomy and sprains, check out these articles on BOFAS and SPORTS-Health.

Why Not Running Could Lead to Bad Bone Health

Is staying active and fit enough to avoid bone loss? Maintaining high bone mineral density (BMD) is important for preventing osteoporosis, fractures, and other conditions associated with bad bone health. However, high-impact sports that often involve running or jumping might be necessary in order to preserve and improve BMD among athletes of all ages. Low-impact sports (such as cycling) as well as weight training may not be enough to maintain high BMD and avoid associated health risks.

Among senior athletes, a 2005 study examined BMD among those competing in the Senior Olympics [1]. They concluded that competing in high-impact sports (basketball, running, volleyball, track and field, and triathlon) correlated with a higher BMD compared to low-impact sports (including cycling, race walking, and swimming), among other factors such as younger age and absence of obesity. Similar results were found in a Norwegian study comparing elite cyclists and runners, as cyclists—despite heavy weights programs as part of their training—were shown to have lower BMD than runners [2].

On the other hand, a study comparing younger men and women showed BMD increases as a result of resistance training, but only among men in the spine and neck. Women showed no significant BMD increase [3].

Bone mass changes with age, peaking for both genders at around 30-40 years old.
Modified from Wikimedia Commons

In light of unsubstantial data to support resistance training as a method to increase BMD, why do many articles online praise weight training as the perfect way to promote healthy bones? Online articles with catchy titles claim that “resistance training is really the best way to maintain and enhance total-body bone strength” and it “increases bone mineral density,” but either provide no sources or cite research that showed no significant increase in BMD [4] [5] [6] [7]. Promoting weight training as the perfect solution to late-in-life bone problems sounds wonderful, but formal research concerning its effects on BMD is as best contested and inconsistent. It is not a blanket solution for those looking to improve bone health through staying fit, and should not be used as the only supplement to other low-impact sports such as cycling or swimming.

Running is among high-impact sports that can promote bone health
Modified from Wikimedia Commons

Ultimately, it seems as though staying fit through low-impact sports and weight training might put an athlete at risk for low BMD and associated health risks. Regular participation in high-impact sports (such as running, basketball, and volleyball) has been shown to correlate with higher BMD across different age groups and athletic skill levels [1] [2]. Even though cycling and weight training might cover all the bases from cardiovascular and strength fitness standpoints, bone health requires more impact than just staying fit.

For further reading on the relationship between running and bone health and how other factors play a role, look at Runner’s World’s article.

 

[1] Leigey D, Irrgang J, Francis K, Cohen P, Wright V. Participation in High-Impact Sports Predicts Bone Mineral Density in Senior Olympic Athletes. Sage: Sports Health. 2009. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445153/]

[2] Andersen OK, Clarsen B, Garthe I, Morland M, Stensrud T. Bone health in elite Norwegian endurance cyclists and runners: a cross-sectional study. BMJ Open Sport & Exercise Medicine. 2018. [https://bmjopensem.bmj.com/content/4/1/e000449]

[3] Almstedt HC, Canepa JA, Ramirez DA, Shoepe TC. Changes in bone mineral density in response to 24 weeks of resistance training in college-age men and women. Journal of Strength and Conditioning Research. 2011. [https://www.ncbi.nlm.nih.gov/pubmed/20647940]

[4] Heid, M. (2017, June 6). Why Weight Training Is Ridiculously Good For You. Retrieved from http://time.com/4803697/bodybuilding-strength-training/

[5] (2018, February 2). 10 Health Benefits of Strength Training That Are Backed by Science. Retrieved from https://www.myoleanfitness.com/health-benefits-of-strength-training/

[6] Nelson ME, Fiatarone MA, Morganti CM, Trice I, Greenberg RA, Evans WJ. Effects of high-intensity strength training on multiple risk factors for osteoporotic fractures. A randomized controlled trial. JAMA. 1994. [https://www.ncbi.nlm.nih.gov/pubmed/7990242]

[7] Going SB, Laudermilk M. Osteoporosis and Strength Training. American Journal of Lifestyle Medicine. 2009. [https://journals.sagepub.com/doi/abs/10.1177/1559827609334979]

A Mystery: How Can Distance Runners Avoid the Most Common and Dreaded Injury?

Man running on track surface.
Photo by Steven Lelham on Unsplash

Stress fractures are small cracks in the bone produced by repetitive stress. The most common locations include the tibia, fibula, and navicular bone [1]. An article by Crowell and Davis on gait analysis stated the occurrence of bone stress injuries in track and field athletes (male and female) to be as high as 21% [2]. Furthermore, approximately 50% of female track and field athletes have had at least one stress fracture [3] . Bone stress injuries  can have a devastating effect on the athlete, their team, and the willingness of these runners to continue to compete. The only treatment for stress fractures is to completely stop running for an average of 6-8 weeks [4].   Runners have no clear and confirmed guidance on injury prevention or appropriate volume of training.

Female Athlete Triad triangle consisting of energy deficiency, low bone density, and menstrual disturbance that make up the three corners of the triangle.
Female Athlete Clinic, Children’s Wisconsin, 2019

Most studies of stress fractures in women have been looked at from a purely biological standpoint. As seen in an article by Hames and Feingold, the female athlete triad is often considered the main reason for the large number stress fractures in female distance runners [5]. The female athlete triad is the connection between energy deficit (due to excessive exercise or under nutrition) and irregular hormone levels which cause a decrease in bone mineral density.  However, despite normal bone density and hormone levels, many competitive runners continue to suffer from season or career-ending stress fractures [6].

Taking a more mechanical rather than biological approach, the source of stress fractures can be explained in the same way as any other material fatigue. A fatigue fracture is caused by a repetitive cyclic stress. For example, consider a paper clip. When a paper clip is bent just once, it does not break. After bending it several times, the paper clip will eventually fracture. This same concept can be applied to bones with forces caused by running. There are two main differences. First, while a paper clip will break through an abundance of minimal stresses over an extended period of time, the bone works to regenerate, with the help of osteoblasts, to compensate for added stress [7].  However, the body’s work to restore the bone is unsuccessful if there is not enough time for repair. Secondly, unlike a paperclip, muscles surround the bone that work to absorb the impact stress. At a given force, the muscles are unable to adequately protect the bone. With a high force frequency and magnitude, a bone stress injury occurs.

While the reason behind stress fractures is known, the mystery of  how to reduce the risk remains. For many competitive runners, dramatically increasing recovery time or reducing mileage is not an option. There are several different factors than might play a distinct role in the solution, including footwear, running form, and running surfaces.

For more information, visit the following articles:

Preventing Stress Fractures“,

Risk Factors for Recurrent Stress Fractures in Athletes“,

Biomechanical Factors Associated with Tibial Stress Fracture in Female Runners.”

“The Relationship between Lower-Extremity Stress Fractures and the Ground Reaction Force: A Systematic Review.”

References:

[1] “Breaking Point: when running stress gets too much.”

[2] “Models for the pathogenesis of stress fractures in athletes.

[3] “Biomechanical factors associated with tibial stress fracture in female runners.”

[4] “Stress Fractures of the foot and ankle.”

[5] “Female Athlete triad and stress fractures.” 

[6] “Sex-related Differences in Sports Medicine: Bone Health and Stress Fractures.”

[7] “The relationship between lower-extremity stress fractures and the ground reaction force: A systematic review”

What an Optimized Running Gait Can Do for You

Running is one of the oldest and most common forms of exercise, but there are many ways that running mechanics vary from person to person. Identifying the different running gaits is important so that their efficiencies and effects on the body can be analyzed. Injuries in runners are common and having an understanding of how different gaits apply stresses on the body differently can be used to educate runners on how to run in a way that will reduce the risk of injury.

Running with poor mechanics can lead to overuse injuries, which are more common than acute injuries in serious runners. The majority of these injuries occur in the leg either at or below the knee and include patellofemoral pain syndrome (PFPS) and medial tibial stress syndrome (shin splints). Running gait analysis can be used to identify the poor mechanics and the potential risks associated with the mechanics. Further studies have grouped the variations so that the effects of similar gaits can be identified. Extensive analysis has led to the identification of several potential variations in running gait.

A study at Shanghai Jiao Tong University‘s School of Mechanical Engineering determined the effects of step rate, trunk posture, and footstrike pattern on the impact experienced by the runner. Data was collected by instructing runners to run with specified gait characteristics. Sensors made used to make sure that the gait was correct and the impact forces on the running surface were measured. This study showed the lowest impact was experienced with a high step rate, a forefoot strike pattern, and an increased anterior lean angle. Limiting the impact reduces the effects of the loading. As a result, running with these gait characteristics reduces the risk of knee pain and stress fracture in the tibia.

Runner on treadmill with attached sensors following instructions to modify gait
from: Huang, Xia, Gang, Sulin, Cheunge, & Shulla, 2019

While the most important factor in this analysis is how forces are translated through the body, this is difficult to measure directly. The technology does not exist to measure these forces accurately and noninvasively. Since invasive techniques would not allow the person to run normally, indirect ways of measuring this data have been developed. One of these alternatives involves collecting kinematic data which can be used to calculate the forces and observe different gait patterns. They do this by recording high speed video of runners. Usually, photo reflective stickers or LEDs are fixed to critical points of motion so that the motion of these points relative to each other can be plotted and analyzed. This data can be used to develop algorithms that describe different gaits.

Running gait does not only affect risk of injury, but also efficiency. Kinematic studies have shown that as running speed increases, a runner’s gait changes to accommodate this change in speed. One change in the gait was the foot strike pattern changed from rear foot to forefoot. This motion shortens the gait cycle and increases the step rate. However, when the runners ran at their top speeds for an extended period of time, their mechanics broke down and some of the gait characteristics that increase injury risk became pronounced. Because of this tendency, incremental training with focus on proper mechanics is necessary to reduce injury risk.

 

 

 

Runner’s Knee: Knee Pain Isn’t Just for Old People

Don’t knee problems only plague old people or people who have run for a lifetime? I questioned this when, for the seventh time in a row, my knee was hurting only a mile and a half into my run. I’m too young for this! However, a plethora of information suggests that knee pain is perhaps not so uncommon in younger runners and athletes as I thought.

The American Family Physican published an article detailing one form of knee injury informally called “Runner’s Knee”. A shockingly high number, between 16 and 25 percent, of running related injuries fall into this categorization. Medically termed patellofemoral pain syndrome (PFPS), the ailment manifests in pain or stiffness in the knee, particularly when bent in load-bearing scenarios such as walking, running, jumping, or squatting. The patellar region experiences shocking loads even in the day to day: in walking alone the region experiences up to a half the person’s body weight while in an activity like squatting it can experience up to seven times one’s body weight. Often the pain is hard to pinpoint but occurs in or around the front of the knee within a circular range. It can inhibit or put a stop to training, however, if addressed early on, can often be healed or corrected much more quickly.

an animated image of a runner mid-stride with the pain region for patellofemoral pain syndrome highlighted
Photo by www.scientificanimations.com from Wikimedia Commons

In PFPS, the patella (the kneecap) moves abnormally within the groove on the end of the femur (called the femoral trochlear groove) due to imbalanced or unusual loads on the joint. This results in over-stressing the joint and causing pain. Several possible causes exist for PFPS; here, I will focus on three of most commonly cited: increased intensity of activity, weak hip muscles, and overpronation.

an image of the muscular and skeletal structure of the knee, including the patella
Photo by BruceBlaus on Wikimedia Commons

Increased Activity

One review explored that women are more likely to suffer from PFPS. In this study they saw that women of higher activity levels were not necessarily more likely to experience pain due to PFPS than women who had a lower activity level. Rather, a substantial increase in activity level seemed to be the cause of pain. Therefore, more than overuse of muscles or joints, PFPS often develops with increased amounts of activity, or temporary overuse, such that the body is not prepared to handle the increased and repetitive forces on the knee.

Weakness in Hip Muscle Strength 

This study shows that lower extremity mechanics and motion can be affected by hip strength. For example, inward rotation of the hip can be lessened through strengthening of hip muscles that counteract that rotation. With less internal hip rotation, the knee abduction moment (the tendency of the knee, due to reaction forces from the ground, to rotate  inward and away from the balanced midline of the knee joint) decreased which often resulted in less stress in the knee. Therefore, the review suggests that strengthening hip muscles can lower the patellofemoral joint stress and help treat PFPS. 

Overpronation

Pronation refers to the natural movement of one’s foot and ankle slightly inward while stepping. When the ankle rotates too far inwards, it is called overpronation. Overpronation can lead to further improper structural alignment in the lower body as the tibia rotates improperly in response to the ankle rotation. The tibia’s rotation then disrupts the natural movement of the patellar joint and can contribute to PFPS. In many cases, overpronation can be corrected through use of orthotic shoe inserts that prevent the over-rotation of the foot and ankle.

In conclusion, while we may often associate knee problems with older people or arthritis, PFPS affects many athletes, particularly runners, at any age. Often, proper training programs that do not accelerate activity too quickly, strengthening exercises that focus on the hip muscles, and proper, overpronation-correcting footwear can treat or prevent an individual from being affected by PFPS. Check out some strengthening exercises here.

The Unfair Advantage: Prosthetics and Their Role in the Olympics

In 2012, the “Blade Runner” Oscar Pistorius became the first double amputee to compete in the Olympics. Ever since this historic occasion, the issue of whether prosthetics should be allowed in athletics has been a topic of controversy in the media. Do prosthetics give amputees an advantage over able-bodied athletes? Are athletes with prosthetics capable of running faster and performing better than able-bodied athletes?

Oscar Pristorius strapped into a harness and being tested on a treadmill by Alena Grabowski's research team.
Photo by Jeff Fitlow/Rice, ScienceDaily 2008

In a recent article, physiology and biomechanics professor Alena Grabowski attempts to answer some of these questions. Grabowski was part of a research group that conducted a study to see if Pistorius’s prosthetics gave him any advantages after he was banned from competing in the 2008 Olympics. The group focused on comparing the abilities of Pistorius to those of able-bodied track athletes. The study involved testing Pistorius’ energy cost in running, his endurance, and his general running mechanics. In order to test for energy costs, the researchers measured breathing and metabolic rates of able-bodied runners who were similar in ability to Pistorius as they ran a series of short sprints. To test endurance, runners were placed on treadmills set at their max speed to measure how long they could maintain that speed. To test the running mechanics, each runner was asked to continue increasing their speed on a treadmill until they could no longer take eight consecutive strides on the treadmill without maintaining their position on the treadmill. Based on the study, the group was able to determine that Pistorius’ running abilities are very similar to able-bodied runners, thus allowing his ban to be lifted and for him to ultimately compete in the 2012 Olympics.

The three variations of prosthetics used in Alena Grabkowski's prosthetic parameters research.
Photo from The Royal Society Publishing 2017

After the initial research, Grabowski decided to conduct research of her own into prosthetics. Her study involved how changing key parameters in a prosthetic affected a runner’s abilities. In order to conduct the tests, she first modeled the foot as a spring system. This allowed her to pick the key parameters to change: stiffness, height, and speed of a prosthetic. Five participants were chosen to be tested. The study consisted of a participant using a set prosthetic to run on a treadmill, increasing the speed on each trial until they could no longer hold their position in the treadmill. This was repeated for different parameter changes in the prosthetics until enough data was collected to compare. From her study, Grabowski found that the length of the prosthetic had no overall effect on running speed. However, stiffness did appear to aid runners, but the effects were negligible at high running speeds. Thus, the advantages of having prosthetics come into play more for long distance running than for sprints. Based on her research finding, Grabowski hopes that future prosthetic development can be more tailored to match the specific wearers abilities before amputation.

The world of prosthetics opens up the door for many amputees to compete in an able-bodied society: from being able to complete just simple day-to-day tasks to competing alongside able-bodied athletes in the Olympics. Though many may still be skeptical of the use of prosthetics in competition—namely running, the evidence says that the effects are minimal or even no-existent in the case of sprinters. With the help of researchers like Alena Grabowski, more athletes like Oscar Pistorius are and hopefully will be making great strides in the future.

For more information on this story, make sure to read The Daily Beast, Scientific American, and The New York Times.

Walk [Under] Water: The Benefits of Underwater Running

Just because you can’t walk on water doesn’t mean you shouldn’t run under it!

Aqua-jogging. Hydro-running. Water-treadmills. Have you ever heard some combination of these terms and wondered what the hype is?

Running underwater offers benefits for people throughout their fitness journey. Underwater running has proven useful for a variety of focuses, including recovery after injury, cross training, and even improved gait. This article includes a video showing a Runner’s World coach tries out a Hydrotrack and discusses some of the benefits!

So, why does it work?

Three basic water properties: hydrostatic pressure, buoyancy, and viscosity.

Hydrostatic pressure is the force that the water exerts on a submerged point. Hydrostatic pressure acts all around the point. However, since hydrostatic pressure is proportional to the weight of liquid above the point, it increases with increased water depth. This means that your feet would experience greater hydrostatic pressures than your knees. While running, this pressure helps support your body and decrease impact forces. In addition to helping prevent injuries through a decreased risk of falling, it also helps decrease swelling and promote cardiovascular health. This article talks about the specifics of pressure with swelling and the cardiovascular system.

Diagram showing hydrostatic forces. Magnitude of the hydrostatic force is larger as it goes deeper below the surface.
Hydrostatic pressure acts on all sides of a point. The pressure increases with depth. Created in Microsoft PowerPoint.

Buoyancy is the hydrostatic force applied to an object with volume (rather than just a point). Since they are at the same depth, all the horizontal forces cancel out. Since the bottom of the object is deeper than the top, the net buoyant force on the object pushes up. The difference between the buoyant force and the weight of the object submerged determines if the object will rise, sink, or stay in place. Thus, the more submerged a person is, the more of their weight is supported. This research article explains how this support can help make gait analysis more effective to further prevent injury. When water reaches the person’s navel, 50% of their weight is supported. This weight bearing capability of water decreases forces on joints and can even help improve range of motion. This allows physical therapy to begin sooner and, overall, take less time out of the patient’s normal routine. This allows shorter rehabilitation times without sacrificing quality of care or recovery.

 

Diagrams showing how the hydrostatic force varies around the submerged object due to depth. The side forces cancel out at equal depth leaving a net buoyant force acting upward against the downward force of the object weight.
Buoyant forces cancel out on the sides leading to the second image showing the net buoyant force and the weight of the object. Created in Microsoft PowerPoint.

Viscosity is a fluid property that affects the resistance that an object encounters during motion. In the case of underwater running, viscosity explains why you move significantly slower in water than on land. It also can offer resistance up to 15 times the amount of resistance on land. Forcing your limbs through the water strengthens muscles that are not typically used out of the water and even burns more calories!

As noted above, viscosity can help strengthen muscles as shown in this study on deep water running (DWR) in a community of elderly women shows how viscosity affects overall strength training. It showed that the women who participated in DWR increased their muscle strength (measured through power) and performed better in various tests, including ones that involved sitting down and getting up. The study showed that deep water running helped to mitigate some of the negative muscular effects of aging.

Overall, running underwater offers some great benefits. The basic properties of water (hydrostatic pressure, buoyancy, and viscosity) provide scientific background for why hydro-running provides benefits for all.