The Psychological Benefits of Exercise

brainhealthFew can argue the many benefits of exercise—it makes people stronger, healthier, and adds years to their lives. There are also a number of less tangible effects of exercise in addition to well-defined muscles and slimmer waistlines. From a psychological perspective, exercise is one of the most important things a person can do to promote mental well-being and overall happiness. Many people are familiar with the mood-boosting effects of exercising regularly, but what is actually happening inside your brain in the midst of a good workout?

Read the basic psychological benefits of exercise or learn the more technical details.

Articles by Alycia Parnell.

The Psychological Benefits of Exercise (Basic)

happy-woman-after-runFew can argue the benefits of exercise—it makes us stronger, healthier, and adds years to our lives. In addition to promoting well-defined muscles and slimmer waistlines, exercise is also one of the most important things a person can do to promote psychological well-being and overall happiness.

Many discussions involving the brain-boosting effects of exercise involve the word ‘endorphins.’ These are a group of chemicals in the brain that act as natural painkillers and resemble opiate drugs such as morphine (Levinthal 2008), which is no coincidence—heightened moods during and after exercise are very similar to the sensations outlined by people describing drug or trance states (Dietrich and McDaniel 2004). In times of stress or pain, such as a strenuous workout, endorphins block the transmission of pain impulses to the brain and create an elevated mood (McGovern 2005). Researchers in a 2008 study of ‘runner’s high,’ or the euphoric state often described by endurance athletes, scanned runners’ brains before and after long runs, revealing that sustained exercise promoted the release of endorphins in brain regions where emotional processing occurs (Boecker et al. 2008).

In addition to the short-term positive effects of a workout such as runner’s high, exercise has powerful long term effects in terms of depression and overall mental health. Several large-scale studies  have shown that people who exercise moderate amounts every week were less anxious, depressed, and neurotic, and had higher levels of general well-being than more sedentary participants (Hassmén et al. 2000, De Moor et al. 2006). Exercise does even more than elevate mood and alleviate depression; it can actually promote changes in the brain through neurogenesis, or the creation of new brain cells. These brain cells, called neurons, appear in the hippocampus, the brain structure in charge of learning and memory (McGovern 2005). Laboratory studies have shown more complex networks of neurons among subjects who exercise regularly than those who don’t (Comery et al. 1996). One possible reason for this could be a protein that promotes growth in the hippocampus after mild stresses associated with exercise (Mattson et al. 2004). Additional animal studies have also shown that this protein could be partially responsible for the positive effect of exercise on depression (Zheng et al. 2006).

Exercise can combat the symptoms of an aging brain. Beginning at age 30, the human brain begins to lose nerve tissue. Since exercise creates more complex networks in the brain, it could serve a preventive role for brain disorders that progress through loss of neurons, such as Alzheimer’s disease (McGovern 2005). Regular physical activity can reduce the risk of dementia by 28% and Alzheimer’s by 45% (Hamer and Chida 2009), and also reduce cognitive decline in the older population at large. Older adults who exercise regularly experience significant improvements in tasks such as planning, inhibition, and working memory (Kramer et al. 1999). A study of patients already diagnosed with Alzheimer’s disease found that those involved in a care plan including 60 minutes of exercise per week showed lower rates of institutionalization after two years (Teri et al. 2003).

Researchers have sought the perfect dose of exercise for maximum benefits. People reap rewards from any amount, but more seems to be better (Trivedi et al. 2011), and high- and low-intensity are equally effective (King et al. 1993). Clinicians generally recommend moderate-intensity exercise for at least 150 minutes per week (Trivedi et al. 2011). Exercise is a powerful tool in maintaining a healthy lifestyle for both the mind and the body.

By Alycia Parnell

Read the technical details about the psychological benefits of exercise.

Literature Cited 

  1. Boecker, H., T. Sprenger, M.E. Spilker, G. Henriksen, M. Koppenhoefer, K.J. Wagner, M. Valet, A. Berthele, and T.R. Tolle. 2008. The runner’s high: opioidergic mechanisms in the human brain. Cerebral Cortex, 18: 2523-2531.
  2. Comery T.A., C.X. Stamoudis, S.A. Irwin, and W.T. Greenough. 1996. Increased density of multiple-head dendritic spines on medium-sized spiny neurons of the striatum in rats reared in a complex environment. Neurobiology of Learning and Memory 66: 93–96.
  3. Dearman, J., and K.T. Francis. 1983. Plasma levels of catecholamines, cortisol, and beta-endorphins in male athletes after running 26.2, 6, and 2 miles. The Journal of Sports Medicine and Physical Fitness  23: 30-38.
  4. De Moor, M.H, A.L. Beem, J.H. Stubbe, D.I. Boomsma, and E.J. De Geus. 2006. Regular exercise, anxiety, depression and personality: a population-based study. Preventive medicine 42: 273-279.
  5. Dietrich, A., and W.F. McDaniel. 2004. Endocannabinoids and exercise. British Journal of Sports Medicine 38: 536-541.
  6. Hamer, M., and Y. Chida. 2009. Physical activity and risk of neurodegenerative disease: a systematic review of prospective evidence. Psychological Medicine 39: 3.
  7. Hassmén, P., N. Koivula, and A. Uutela. 2000. Physical exercise and psychological well-being: a population study in Finland. Preventive Medicine 30: 17-25.
  8. King, A.C., C.B. Taylor, and W.L. Haskell. 1993. Effects of differing intensities and formats of 12 months of exercise training on psychological outcomes in older adults. Health Psychology 12: 292.
  9. Kramer, A.F., S. Hahn, N.J. Cohen, M.T. Banich, E. McAuley, C.R. Harrison, J. Chason, E. Vakill, L. Bardell, R.A. Boileau, and A. Colcombe. 1999. Ageing, fitness and neurocognitive function. Nature 400: 418-419.
  10. Levinthal, C.F. 2008. Drugs, behavior, and modern society. Pearson, Boston, MA.
  11. Mattson, M.P., W. Duan, R. Wan, and Z. Guo. 2004. Prophylactic activation of neuroprotective stress response pathways by dietary and behavioral manipulations. NeuroRx 1: 111-116.
  12. McGovern, M. K. 2005. The effects of exercise on the brain. Serendip Studio. Bryn Mawr College. <http://198.252.64.61/Support/Studies/The Effects of Exercise on the Brain,,BDNF.pdf>
  13.  Teri, L., L.E. Gibbons, S.M. McCurry, R.G. Logsdon, D.M. Buchner, W.E. Barlow, W.A. Kukull, A.Z. LaCroix, W. McCormick, and E.B. Larson. 2003. Exercise plus behavioral management in patients with Alzheimer disease: a randomized controlled trial. Jama 290: 2015-2022.
  14. Trivedi, M.H., T.L. Greer, T.S. Church, T.J. Carmody, B.D. Grannemann, D.I. Galper, A.L. Dunn, C.P. Earnest, P. Sunderajan, S.S. Henley, and S.N. Blair. 2011. Exercise as an augmentation treatment for nonremitted major depressive disorder: a randomized, parallel dose comparison. Journal of Clinical Psychiatry 72: 677.
  15. Zheng, H., Y. Liu, W. Li, B. Yang, D. Chen, X. Wang, Z. Jiang, H. Wang, Z.Wang, G. Cornelisson, and f. Halberg. 2006. Beneficial effects of exercise and its molecular mechanisms on depression in rats. Behavioural Brain Research 168: 47-55.

The Psychological Benefits of Exercise (Technical)

Few can argue the many benefits of exercise—it makes people stronger, healthier, and adds years to their lives. There are also a number of less tangible effects of exercise in addition to well-defined muscles and slimmer waistlines. From a psychological perspective, exercise is one of the most important things a person can do to promote mental well-being and overall happiness. Many people are familiar with the mood-boosting effects of exercising regularly, but what is actually happening inside your brain in the midst of a good workout?

Exercise and the Brain

brainhealthIt seems that a majority of discussions involving the positive psychological effects of exercise involve the word ‘endorphins.’ Generally speaking, endorphins are a group of chemicals in the brain that act as natural painkillers and bear a strong resemblance to opiates such as morphine and heroin (Levinthal 2008). In fact, the word ‘endorphin’ is derived from the words ‘endogenous’ and ‘morphine,’ referring to the fact that they are produced within the central nervous system and act similarly to morphine (

Leuenberger 2006). In times of stress or pain, such as a strenuous workout, endorphins are released by the pituitary gland and bind to opioid receptors in neurons, thus blocking the transmission of pain impulses to the brain (McGovern 2005). This connection to opiates is not a coincidence. Many people experience a heightened mood during or after exercise, with such varied subjective descriptions as elation, inner harmony, unity with one’s self, and pure happiness. These mood states are very similar to the sensations outlined by people describing drug or trance states (Dietrich and McDaniel 2004).

The role of endorphins in improved mood states during exercise is widely accepted, but research on the matter has been surprisingly conflicting for a topic that is widely perceived as general knowledge (Harber and Sutton 1984). To study the relationship between endorphins and exercise, many earlier studies have used blood plasma levels. Some of these studies have yielded significant increases in blood plasma endorphin levels, while others have not (Leuenberger 2006).  In addition, there is a fundamental issue with this method of research, which is that the pituitary gland produces the endorphins and releases them into the bloodstream, but very few of them are able to reenter the brain through the blood brain barrier, which is the brain’s protective mechanism selecting what materials can enter from the bloodstream (Dearman and Francis 1983). In 2008, Dr. Henning Boecker came up with some conclusive research on the subject while studying ‘runner’s high,’ or the euphoric state often described by endurance athletes. Rather than blood plasma screening, Boecker employed Positron Emission Tomography (PET). During the study, ten athletes were scanned in a rest state and then again after two hours of endurance running. The scans revealed that sustained physical exercise did indeed promote the release of endogenous opioids in frontolimbic brain regions (where emotional processing occurs), and that there is a close correlation to the perceived euphoria of distance runners (Boecker et al. 2008).

In addition to the short-term positive effects of a workout such as runner’s high, exercise has powerful long-term effects in terms of depression and general feelings of well-being. A large-scale Finnish study had 3,403 participants answer questionnaires about their fitness habits and psychological states. The findings revealed that participants who exercised two to three times per week experienced less depression, anger, cynical distrust, and stress than those who exercised less or not at all. The psychological inventories used indicate enhanced levels of general psychological well-being among the participants (Hassmén et al. 2000). Another large population-based study of 19,288 people found that individuals who exercised at least 60 minutes per week were less anxious, depressed, and neurotic than more sedentary participants (De Moor et al. 2006).

The psychological implications of exercise are even more expansive benefits than elevating mood and alleviating depression. In addition to creating happier people, it can actually promote physiological changes in the brain through neurogenesis, or the creation of new neurons. These neurons appear in the hippocampus, which is the structure in the brain that is responsible for learning and memory (McGovern 2005). Laboratory studies on animal subjects have shown increased complexity of dendrites in the cerebral cortex, which are the parts of neurons that receive signals and thus allow for more complex brain function (Comery et al. 1996). The mechanisms involved in exercise-induced neurogenesis are still being investigated, but recent research has revealed that a protein called brain-derived neurotrophic factor, or BDNF, plays a pivotal role. The mild stresses associated with exercise promote the influx of calcium, which activates transcription factors that tell the BDNF gene to promote neuron growth in the hippocampus (Mattson et al. 2004). Additional animal studies focusing on BDNF in the context of depression have indicated that exercise-induced BDNF production could be partially responsible for the positive effect of exercise on depression symptoms (Zheng et al. 2006). Thanks to BDNF, regular exercise not only promotes happiness, it can also make your brain work better when it comes to learning and memory.

Exercise and Mental Ageing

This role of exercise in learning and memory is significant in the context of cognitive decline and neurodegenerative disorders. Beginning at age 30, the human brain begins to lose nerve tissue. Since aerobic exercise creates a denser network of dendrites between neurons, it could help serve a preventive role for diseases such as Alzheimer’s that progress through loss of neurons (McGovern 2005). One meta-analysis of studies examining the connection between exercise and cognitive decline revealed that regular physical activity reduced the risk of dementia by 28% and Alzheimer’s disease by 45% (Hamer and Chida 2009). In addition to its role in neurodegenerative disorders, exercise has been shown to reduce cognitive decline in the older population at large. One study examined a group of 124 older adults between the ages of 60 and 75 years old in relation to executive control processes such as planning, inhibition, and working memory. The subjects were assigned to either aerobic or anaerobic exercise, such as walking and stretching, respectively. The study revealed significant improvements in tasks requiring executive control among the people who engaged in aerobic exercise (Kramer et al. 1999).

How Much Exercise is Best?

happy-woman-after-runThe results of the previously described studies raise the question, what kind of exercise yields the greatest psychological benefits, and in what doses? A 2011 study of patients suffering from major depressive disorder examined the efficacy of different doses of exercise in relieving their symptoms. One group of subjects was assigned to burn four calories per kilogram of body weight per week, while the second group burned 16 calories per kilogram per week. The study revealed that both groups of patients experienced relief of their depressive symptoms, but the group that exercised more experienced greater benefits (Trivedi et al. 2011). In the context of neurodegenerative disorders, a study of patients already diagnosed with Alzheimer’s disease found that those who were involved in a care plan including at least 60 minutes of exercise per week showed lower rates of institutionalization due to behavioral disturbance after two years (Teri et al. 2003).

Regarding intensity of exercise required to attain psychological benefits, one study showed that all subjects experienced positive results whether they were assigned to a group instructed to perform high-intensity or low-intensity exercise (King et al. 1993). With the varying research available detailing specific dosage, it appears to be a consensus that anything helps. For optimal physical and psychological benefits, clinicians generally recommend moderate-intensity exercise for at least 150 minutes per week (Trivedi et al. 2011).

Potential Psychological Consequences of Exercise

In light of the plentiful data on psychological benefits of exercise, one must wonder if there are any negative consequences. In some cases, people can develop exercise dependence, in which exercise becomes a compulsion that interferes with daily life and relationships. Since exercise releases endorphins, and such opiodergic activity is also involved in addiction, there could be a relationship between endorphin release and exercise dependence (Leuenberger 2006). In addition, individuals who take part in regular exercise and then experience an interruption in their routine due to injury or other factors could experience negative psychological effects. One study of runners found that those who were deprived of running for two weeks experienced greater levels of psychological distress, such as depression, anxiety, and lowered self-esteem, than those who experienced no interruption in their training (Chan and Grossman 1988). It is generally agreed upon that exercise deprivation among habitual exercisers induces a negative psychological response, but it is difficult to recruit individuals for further study who are willing to give up their habits long enough to participate (Szabo 1995).

Conclusion

The many benefits of exercise clearly apply to the mind as well as the body, whether it’s a short-term rush from the release of endorphins from a good run, or a powerful weapon against the long-term effects of clinical depression. Not only does it promote happiness and well-being, it also helps the brain perform better and ward off cognitive decline as we age. It is apparent that regular exercise can do little but help your brain achieve its potential. If the motivation of a strong body is not enough to initiate a workout plan, considering the brain could be a helpful tool in maintaining a healthy lifestyle with plenty of physical activity.

By Alycia Parnell
Alycia Parnell holds degrees in Psychology and Environmental Studies from the University of Utah. She lives, works, and writes in Salt Lake City.

Literature Cited 

  1. Boecker, H., T. Sprenger, M.E. Spilker, G. Henriksen, M. Koppenhoefer, K.J. Wagner, M. Valet, A. Berthele, and T.R. Tolle. 2008. The runner’s high: opioidergic mechanisms in the human brain. Cerebral Cortex, 18: 2523-2531.
  2. Chan, C.S., and H.Y. Grossman. 1988. Psychological effects of running loss on consistent runners. Perceptual and Motor Skills 66: 875-883.
  3. Comery T.A., C.X. Stamoudis, S.A. Irwin, and W.T. Greenough. 1996. Increased density of multiple-head dendritic spines on medium-sized spiny neurons of the striatum in rats reared in a complex environment. Neurobiology of Learning and Memory 66: 93–96.
  4. Dearman, J., and K.T. Francis. 1983. Plasma levels of catecholamines, cortisol, and beta-endorphins in male athletes after running 26.2, 6, and 2 miles. The Journal of Sports Medicine and Physical Fitness  23: 30-38.
  5. De Moor, M.H, A.L. Beem, J.H. Stubbe, D.I. Boomsma, and E.J. De Geus. 2006. Regular exercise, anxiety, depression and personality: a population-based study. Preventive medicine 42: 273-279.
  6. Dietrich, A., and W.F. McDaniel. 2004. Endocannabinoids and exercise. British Journal of Sports Medicine 38: 536-541.
  7. Hamer, M., and Y. Chida. 2009. Physical activity and risk of neurodegenerative disease: a systematic review of prospective evidence. Psychological Medicine 39: 3.
  8. Hassmén, P., N. Koivula, and A. Uutela. 2000. Physical exercise and psychological well-being: a population study in Finland. Preventive Medicine 30: 17-25.
  9. King, A.C., C.B. Taylor, and W.L. Haskell. 1993. Effects of differing intensities and formats of 12 months of exercise training on psychological outcomes in older adults. Health Psychology 12: 292.
  10. Kramer, A.F., S. Hahn, N.J. Cohen, M.T. Banich, E. McAuley, C.R. Harrison, J. Chason, E. Vakill, L. Bardell, R.A. Boileau, and A. Colcombe. 1999. Ageing, fitness and neurocognitive function. Nature 400: 418-419.
  11. Leuenberger, A. 2006. Endorphins, exercise, and addictions: a review of exercise dependence. Impulse: the Premier Journal for Undergraduate Publications in the Neurosciences 3: 1-9.
  12. Levinthal, C.F. 2008. Drugs, behavior, and modern society. Pearson, Boston, MA.
  13. Mattson, M.P., W. Duan, R. Wan, and Z. Guo. 2004. Prophylactic activation of neuroprotective stress response pathways by dietary and behavioral manipulations. NeuroRx 1: 111-116.
  14. McGovern, M. K. 2005. The effects of exercise on the brain. Serendip Studio. Bryn Mawr College. <http://198.252.64.61/Support/Studies/The Effects of Exercise on the Brain,,BDNF.pdf>
  15. Szabo, A. 1995. The impact of exercise deprivation on well-being of habitual exercisers. Australian Journal of Science and Medicine in Sport 27: 68-77.
  16. Teri, L., L.E. Gibbons, S.M. McCurry, R.G. Logsdon, D.M. Buchner, W.E. Barlow, W.A. Kukull, A.Z. LaCroix, W. McCormick, and E.B. Larson. 2003. Exercise plus behavioral management in patients with Alzheimer disease: a randomized controlled trial. Jama 290: 2015-2022.
  17. Trivedi, M.H., T.L. Greer, T.S. Church, T.J. Carmody, B.D. Grannemann, D.I. Galper, A.L. Dunn, C.P. Earnest, P. Sunderajan, S.S. Henley, and S.N. Blair. 2011. Exercise as an augmentation treatment for nonremitted major depressive disorder: a randomized, parallel dose comparison. Journal of Clinical Psychiatry 72: 677.
  18. Zheng, H., Y. Liu, W. Li, B. Yang, D. Chen, X. Wang, Z. Jiang, H. Wang, Z.Wang, G. Cornelisson, and f. Halberg. 2006. Beneficial effects of exercise and its molecular mechanisms on depression in rats. Behavioural Brain Research 168: 47-55.

Repeating Great Performances with Muscle Memory

labeled_diagram_human_brainHave you ever wondered how professional tennis players are able to put a serve right on the line time after time? How about how a professional golfer is able to pull off pin-point shots with extreme consistency? Aside from intense focus, these athletes are using motor learning, also known as muscle memory. This is essentially teaching your muscles how to repeat movements or techniques over and over.

Learn the basics of how muscle memory matters.

Article by Kenny Morley

Understanding Head Injuries Through Biomechanics and Math

soccer-header

In biomechanics, systems in motion — such as the impact of a ball on a player’s head — are described or “modeled” by mathematical differential equations. For example, these equations can show the relationship between the acceleration or force of the ball to the head at impact, and the change in shape of brain tissue in response to that form. The solution to these equations provides information that could be used to establish new safety regulations or adequate sports gear for players.

Current studies show that heading the ball may not be as much of a concern as physicians and parents thought, although it is not fully understood how repetitive head shooting, through many years of play, affects players. Further research will continue to help treat and prevent injuries, and improve athlete performance through individualized coaching.

Learn more about the basics of head injuries and biomechanics or read the more technical mathematical explanation.

Article by Cristian Clavijo

Understanding Head Injuries through Biomechanics and Math (Basic)

soccer-headerIt is estimated that approximately 33 billion viewers watched the 1998 FIFA World Cup over the course of its 64 games (Kirkendall, Jordan & Garrett 2001).  Fans from all nations have a thorough understanding of the rules of soccer, which if broken are often manifested by yellow or red cards.  What fans, players and even coaches sometimes do not readily recognize are the behind-the-scene rules or laws that govern the game of soccer much more strictly than those enforced by the referees.  These are the laws of physics.  They govern how high a player can jump, how much the ball can spin as it travels across the field, and even how well a soccer player can take hits.  This last area in particular has received growing clinical interest since injuries related to soccer are an ever increasing concern.

The past 50 years have seen rapid improvements in medicine, bioengineering and computers.  It is the interdisciplinary collaboration of these three fields that has given birth to the field of biomechanics.  While biomechanics has become diverse and broad, it basically uses mathematical differential equations to describe known physical phenomena within the human body as it reacts to external mechanical stimuli.  Since the system of equations created is often impossible to solve by hand, computers integrate the system of equations and approximate solutions.  To set up a robust and valid system of equations is not easy and requires practical experience as well as academic knowledge.  Many assumptions have to be justifiably made, boundary conditions (values required to arrive at a solution of any differential equation) have to be established, and while no mathematical model will ever exactly predict “real life” behavior, its accuracy at times can be extremely helpful and insightful for clinical and scientific purposes.

The challenges encountered by biomechanical engineers are many.  First of all, differential equations require known mechanical properties of biological tissues.  These values, which are obtained empirically, are hard to capture by conventional engineering devices and techniques that traditionally only deal with more homogeneous materials.  Several different measurement devices have been created to measure biological tissue mechanical properties (Bartsch et al 2012).  Once these mechanical properties values are procured, then the math begins.  These values are plugged into the differential equations as constants or functions. Once solved, these equations are validated through experiments to see if they are accurate.  Once validated, the equations are used to study deformation and other desired variables.

Though ongoing research in the field of biomechanics for soccer head trauma will continue to generate further discoveries, current studies show that heading the ball may not be as much of a concern as physicians and parents thought (Broglio et al. 2004). More research is necessary to fully understand the repetitive nature of head shooting for those engaged in the sport through many years.  Further development in the area of computing, mathematics, engineering and medicine will continue to provide more answers for parents and coaches.

Learn the technical biomechanics behind heading a ball.

By: Cristian Clavijo

References 

Asken, M.J. and Schwartz, R.C. 1998. Heading the ball in soccer: What’s the risk of brain injury? The Physician and Sportsmedicine, 26, 11.

Bartsch, A., Benzel, E., Miele, V., Morr, D. and Prakash, V. 2012. Hybrid III anthropomorphic test device (ATD) response to head impacts and potential implications for athletic headgear testing. Accident Analysis and Prevention, 48, 285-291.

Broglio, S.P., Guskiewiez, K.M., Sell, T.C. and Lephart, S.M. 2004. No acute changes in postural control after soccer heading. British Journal of Sports Medicine, 38, 561-567.

Kirkendall, D.T., Jordan, S.E. and Garrett, W.E. 2001. Heading and head injuries in soccer. The American Journal of Sports Medicine, 31, 5:369-386.

Understanding Head Injuries through Biomechanics and Math (Technical)

Often, the first thing that a person newly exposed to a particular sport has to learn is the rules of the game.  Rules are important in any sporting event because they serve as guidelines or limitations to what a player may or may not do.  The rules to any sport are handcrafted by the inventors of the game, redesigned with time, and enforced by officials during game-time.  However, it’s not just the rules of the game, but also the rules (or “laws”) of physics – such as gravity, momentum, and friction – that govern all sporting events. Additionally, there are biophysical laws that also govern the players such as physiological energy production, cardiovascular cooling mechanisms, pain detection, etc. Both of these types of laws, external and internal to the player, must be written in a quantitative language to be conveyed meaningfully.  This language—universal in its nature—is mathematics.

Almost as universal as mathematics is the sport of soccer, known as “football” by international audiences. An estimated 33 billion viewers watched the 1998 FIFA World Cup – over the 64 matches (Kirkendall, Jordan & Garrett 2001).  While most people can’t disagree with the fact that soccer is governed by mathematics and physics, some fail to see the relevance of science in soccer.  One area where science and soccer intersect is sport-related injuries and biomechanics.

The number of sport-related injuries has been reported to be at least 300,000 per year in the US, and in a study of elite soccer players, 89% of the men were found to have some history of head injury, including concussions (Barnes et al. 1998). Within the past few decades, computational power and technology has grown exponentially, permitting advancements in areas that had been “asleep” for centuries.  Engineers and scientists are now able to solve mathematical equations that describe the behavior of biophysical phenomena.  Physicians and sport trainers are now teaming up with engineers to answer injury-related questions for which, up until now, there had only been empirical and observational data.  This new and exciting field is called biomechanics.

Within the sport of soccer alone, the revolutionary field of biomechanics can provide quantitative results that will not only help to better treat and prevent injuries, but also to numerically measure and compare competitions, improve athlete performance and ultimately provide individualized coaching.  For example, sport scientists discovered that merely increasing quadriceps strength will actually decrease jump height with use of the same coordination, but that jump height will increase if jumpers alter their coordination (Bobbert et al. 1996).  Further unanswered questions that have perplexed soccer coaches and physicians for centuries can now be addressed, such as: How much does heading a soccer ball affect the player (see Figure 1)? When are soccer players too young to head the ball? Besides brain tissue deformation, are there other tissue groups adversely affected during heading such as the neck or spine (Al-Kashmiri & Delaney 2006; Bartsch et al. 2012)? Can we compare repetitive long-term ball heading to punches to the head in boxing? How will training and injury treatment be adapted to individual players according to their particular body type?

In biomechanics, systems in motion – such as the impact of a ball on a player’s head – are described or “modeled” by mathematical differential equations.  The solutions to these differential equations show the direct relationship between the dependent and independent variable(s).  The dependent variable may, for example, be the spatial deformation of brain tissue in response to the forces exerted to it by heading the soccer ball.  In this example, the independent variable could be the acceleration or force of the ball to the head of the player at time of impact.  The solution to this equation would tell the coach or physician how much brain tissue is deformed as the force or acceleration of the ball increases.  The answer to these equations can then be coupled with conventional clinical knowledge to establish new safety regulations or adequate sport gear.

Figure 1 Visual of brain tissue deformation under lateral loading

While theoretically biomechanics seems to be the long waited-for solution to understanding sports science in a more quantifiable and accurate manner, it must still overcome many challenges.  The first challenge is the current separation between the two main fields involved in biomechanics: medicine and mechanics (engineering).  Another major challenge is found in attempting to measure and model the mechanical properties of biological tissue.  It is easy to measure mechanical properties of aluminum or steel parts because they are chemically homogeneous and relatively symmetric.  However, most tissues are extremely heterogeneous histologically, even in the microscopic scale, and they also have vague boundaries as they join different tissues.  Furthermore, tissue mechanical properties often are dependent on temperature, pH or external forces and they can change over time.  This makes in-vitro results differ from in-vivo ones and may challenge the model’s validity.  When mechanical properties cannot be kept constant, the differential equations become extremely time-consuming and costly to solve.  Even when mechanical conclusions are reached, certain aspects of pathophysiological processes, such as concussions, are still not fully understood (Kohler 2003).

Despite the obstacles, engineers and doctors have made great strides in biomechanical research.  Many methods have been developed to measure biological tissue properties and predict biomechanical behavior and outcomes.  One common apparatus for measuring strain and deformation of objects is the strain gage and accelerometer.  These gages attach to the subjects and are able to detect mechanical deformation as external forces are exerted (See Figure 1).  Image analysis is another preferred technique to measure the dynamics of systems.  Other widely known techniques include opto-reflective technology, dynamometrics, electromyography, EEG, CT, neurologic exams (Asken & Schwartz 1998) and the newly adapted anthropomorphic test device (Bartsch et al 2012).  Information from these techniques is necessary and often the first step before the mathematical equations come into play.

When deriving differential equations, engineers often “craft” the differential equations on a piece of paper.  The next step usually involves 2D or planar analyses, which augment the complexity of the system of equations but provides more in-depth results.  Head-neck dynamic responses, one of the original research studies in this area, were developed in the sagittal plane in the 1960’s (Mertz & Patrick 1967).  Engineers have only recently started to delve into 3D space.  However, in 3D space, scientists are able to analyze impulsive loading hitting a target in several degrees of freedom (Ivancevic 2009). After a mathematical model, whether 2D or 3D, is finished, it is compared to experimental data in order to be validated.

Using validated models, scientists have been able to establish correct techniques of heading, frequency of impacts, preventative methods and more (Asken & Schwartz 1998). Recent results have shown that lateral headshot impacts cause higher linear acceleration than front or oblique front impacts.  Also, low-energy impacts have been found to produce more uniform stress distribution than high-energy impacts (Bartsch et al 2012).  Others have found that individual impacts cause linear and angular accelerations lower than the levels associated with traumatic brain injury, but attribute damage to constant repetition (Bayly et al. 2002).  Other researchers have similarly found no acute cerebral damage from ball heading (Broglio et al. 2004) but for people who head the ball 1000 – 1500 times per year, lasting damage may develop (Punnoose 2012).  Lastly, even the materials of the soccer ball used during the FIFA World Cup have been reevaluated for better design (Dvorak, Junge & McCrory 2012).  However, even if headshots do not raise as much concern as was expected, biomechanics will still give answers to injury prevention for other types of impacts such as head-to-head and joint impacts (McCrory 2003). Though the direction of biomechanics is still hazy, one thing is certain: it provides important insight into the world of sports injuries and may impact the way athletes play the game.

 

By: Cristian Clavijo, University of Utah
Cristian Clavijo is a native of Peru, moved to the US in the 8th grade, and is now a Masters student in Mechanical Engineering at the University of Utah.  As an advocate for the Hispanic underserved population in Utah, Clavijo is involved in educating children and parents on how basic scientific and medical knowledge can help them progress and become collaborators of their communities.  He plans to pursue a PhD in Mechanical Engineering next year.

References 

Al-Kashmiri, A. and Delaney, J.S. 2006. Head and neck injuries in football (soccer). Journal of Trauma, 8, 189-195.

Asken, M.J. and Schwartz, R.C. 1998. Heading the ball in soccer: What’s the risk of brain injury? The Physician and Sports Medicine, 26, 11.

Barnes, B.C., Cooper, L., Kirkendall, D.T., McDermott, T.P., Jordan, B.D. and Garrett, W.E. 1998. Concussion history in elite male and female soccer players. The American Journal of Sports Medicine, 26, 3:433-438.

Bartsch, A., Benzel, E., Miele, V., Morr, D. and Prakash, V. 2012. Hybrid III anthropomorphic test device (ATD) response to head impacts and potential implications for athletic headgear testing. Accident Analysis and Prevention, 48, 285-291.

Bayly, P.V., Naunheim, R., Standeven, J., Neubauer, J.S., Lewis, L. and Genin, G.M. 2002. Linear and angular accelerations of the human head during heading of a soccer ball. Proceedings of the Second Joint EMBS/BMES Conference, Oct. 23-26.

Bobbert et al. 1996. Medicine and Science in Sports and Science, 28, 1402-1412.

Broglio, S.P., Guskiewiez, K.M., Sell, T.C. and Lephart, S.M. 2004. No acute changes in postural control after soccer heading. British Journal of Sports Medicine, 38, 561-567.

Dvorak, J., Junge, A. and McCrory, P. 2005. Head injuries. British Journal of Sports Medicine, 39, i1-i2.

Fuller, C.W., Junge, A. and Dvorak, J. 2005. A six year prospective study of the incidence and causes of head and neck injuries in international football. British Journal of Sports Medicine, 39, i3-i9.

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Kirkendall, D.T., Jordan, S.E. and Garrett, W.E. 2001. Heading and head injuries in soccer. The American Journal of Sports Medicine, 31, 5:369-386.

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Punnoose, A.R. 2012. Study raises concerns about “heading” in soccer, but jury is still out on risks. The Journal of the American Medical Association, 307, 10:1012-1014.

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Repeating Great Performances with Muscle Memory (Basic)

labeled_diagram_human_brain

The Human Brain

Have you ever wondered how professional tennis players are able to put a serve right on the line time after time? How about how a professional golfer is able to pull off pin-point shots with extreme consistency? Aside from intense focus, these athletes are using motor learning, also known as muscle memory. This is essentially teaching your muscles how to repeat movements or techniques over and over.

The theories that explained motor learning were developed at the beginning of the 20th Century. Dr. Edward Thorndike was a pioneer in the study of motor learning and he conducted various experiments that showed subjects required very minimal training in completing tasks that were learned decades before. These experiments led Thorndike and other scientists to determine that learned motor skills are stored in the memory section of our brains.

We all use muscle memory techniques in our everyday life. Whether it be riding a bicycle, typing on a keyboard or entering a common password or pin number, we have taught our muscles to carry out these commands without putting much thought into them. It takes a great deal of practice and repetition for a task to be completed on a strictly subconscious level. For that professional tennis player or golfer it takes hundreds of hours of practice and repeated shots for the brain and muscles to perform at a world class level.

The process of adding specific motor movements to the brain’s memory can take either a short or long time depending on the type of movements being performed. When movements are first being learned, the muscles and other body-controlling features (such as ligaments and tendons) are stiff and slow and can be easily disrupted if the brain is not completely focused on the movement. In order to complete the memorization, acts must be done with full attention. This is because brain activity increases when performing movements, and this increased activity must be fully centered on the activity being completed. Much of the motor learning in the brain is located in the cerebellum which is the part of the brain in charge of controlling sensory and cognitive functions.

Once actions are memorized by the brain, the muscles must be trained to act in a quick, fluid manner. This can be done in the gym, on the court, or other playing field. When athletes complete strength training exercises, they enhance the synapses in their muscles which increases the speed at which impulses travel from the brain through the nervous system to the muscles. This is key because it lowers the time between when the brain decides to complete a movement to when the muscles actually start to move. This allows tennis players to react to a hard serve or a golfer to adjust the club during his swing. When the perfect shot is carried out, the brain will begin to memorize what it felt like and use the timing of the improved synapses so the action can be repeated.When practicing, you will inevitably hit poor shots every once in awhile. This is where a good attitude comes into play. As stated before, muscle memory comes from focusing on a single action or movement. Unfortunately for some players, when you hit a bad shot, you will focus on this shot because bad shots are more emotionally charged than good shots. For your brain to memorize the good shots, you must attempt to look past the good shots and focus on what you do right on your great shots! If you do this, your brain and muscles will be able to memorize what it feels like to hit a strong shot, and you will become a better player.

Learn more about Muscle Memory.

By: Kenny Morley, Ohio State University 

 

References:

Tennis – Making Muscle Memory for Tennis. (2012). Retrieved from http://fixyourtennis.weebly.com/tennis—making-muscle-memory-for-tennis.html

Thorndike, E. Edward L. Thorndike (1874-1949). (2012). Retrieved from http://www.nwlink.com/~donclark/hrd/history/thorndike.html>.