The Forgotten Factors Contributing to Pathokinematics

The focus of this blog series is on movement and the impact that movement has on performance and injury.  The following is a brief overview of several important factors that can contribute to pathokinematic movement in addition to those cited in the previous series related to differences between males and females.  Several of them are related to nutrition as you will see, which has significant impact on the ability of the athlete to move properly and sustain proper mechanics over time.  In sports medicine, nutrition is one area too often ignored.   

All of these factors influence energy conservation, endurance, speed and power in the athlete.  As we know, when energy levels are low, endurance, speed and power suffer.  Over time, as fatigue continues to set in, an athlete may be subject to an even greater likelihood of poor biomechanics, even if they are not present under well rested conditions.  In other words, even in cases where pathokinematics don’t normally exist in a given athlete, they can be caused by inattention to these issues.  And for those athletes who demonstrate certain lower extremity pathokinematics all the time, inattention to these factors can and does exacerbate them in many cases, especially in situations that require increased endurance, speed, power or strength.

Hydration

Water intake or hydration is a simple aspect of nutrition that has a huge impact on athletic  The   Aside from performance, though, it is critical to remember that water is essential to the human body, and without it we wouldn’t survive to compete in athletic activities.  Estimates are that a human can survive 8-14 days without water, depending on the rate of sweat, urine and tears leaving the body.  Water composes more than half of the human body, and is required for every single body function.  Water helps to:
correlation between hydration and endurance and speed during athletic performance is clearly shown in the research.
performance.

• Transport nutrients
• Dispel waste
• Regulate the body’s temperature
• Aid digestion
• Ensure healthy function of vital organs

Guyton's Textbook of Medical Physiology states that "the total amount of water in a man of average weight (70 kilograms) is approximately 40 liters, averaging 57 percent of his total body weight.”[i]   Specifically, lean muscle tissue contains about 99% water by weight, blood contains almost 70% water, body fat contains 10% water and bone has 22% water.  The human body is about 60% water in adult males and 55% in adult females.[ii]  Knowing that the human body is composed of so much water, the importance of hydration becomes even more apparent, yet it is rarely addressed in sports performance related literature or when treating athletes with injuries. 

The human body is constantly undergoing a complex set of chemical reactions. These chemical reactions are highly dependent on blood pH.  There is some disagreement among researchers about what constitutes a healthy pH in humans, but most agree it ranges from 6.1 to 7.5.  A healthy blood and body pH is essential in order to allow chemical reactions in the body to take place.  The rate limiting step, in most chemical reactions in the human body, is dependent on enzymes.  Enzymes are activated and deactivated by pH levels.  If pH levels are higher or lower than “optimal” then chemical reactions are slowed.  Water is essential to maintain a proper pH balance and therefore is essential for facilitating these reactions at the proper rate.  When water (H20) is introduced into the body, one of the hydrogen molecules cleaves off, leaving H + HO.  This free hydrogen ion aids in making the body’s pH more neutral.  This allows chemical reactions to take place more readily.   Therefore, proper hydration is believed to have the following critical effects in humans: 

1.     Improves muscle repair –  by creating a chemical environment more conducive to protein synthesis and repair of muscular tissue torn down during training

2.     Improves the efficiency of chemical reactions for both aerobic and anaerobic metabolism

3.     Improves viscosity of the blood –

a.     Allows improved oxygen and nutrient transport to muscle tissue

b.     Decreases stress on the heart by increasing stroke volume

4.     Improves elasticity of muscle and ligament tissues – which improves tolerance to the high force demands of athletic activity.

According to research published in the American Journal of Epidemiology in 2002, nearly 50% of the American population is considered clinically dehydrated.[iii]  Dehydration occurs when the amount of body fluid lost is greater than the amount of fluid that is replaced. In this state, the body is unable to cool itself, causing a lack of energy, muscle fatigue, cramps, heat exhaustion or possibly heat stroke.  Appendix J depicts a urine color chart that can be used to assess hydration levels as well as a chart from the Centers for Disease Control and Prevention outlining signs of dehydration.

In order to avoid dehydration and the potential dangers associated with it, the following guidelines should be adhered to:

• Drink fluids before feeling thirsty and before, during and after exercise or prolonged heat exposure;
• Water is the best fluid for everyone and the recommended amount is 0.5 to 1.0 ounces per pound of body weight per day.  Fluids can also come from fruits, juices, soups and vegetables, but these fluids should not be relied upon to replace pure water;
• When exercising with high intensity for more than 45 minutes, sports drinks can replenish lost electrolytes;
• It’s a good idea to keep a water bottle, hands-free system or similar portable container on hand and drink from it throughout the day and especially when exercising;  
• Check the color of urine to see if fluid intake is adequate. Clear or light-colored urine indicates proper hydration;
• Avoid caffeine, some energy drinks and alcohol.  Some energy drinks have high amounts of caffeine which acts as a diuretic and accelerate water loss;
• Take frequent breaks from strenuous, sweat producing activities to hydrate adequately so that the body has time to cool and recover.

The Gatorade Institute has shown that as little as 1% dehydration can result in a 10% decrease in performance in elite athletes[iv].  Although all the mechanisms are not completely understood, it is obvious that hydration can and does play a critical role in performance, endurance, and power.  That being said, there is some variation in recommendations for water consumption, and requirements are highly dependent on activity, environmental conditions and individual needs.  Current recommendations in the literature range from .5 to 1.0 oz/pound of body weight.  When considering your own water needs, it is typically best to measure your current intake and gradually work your way up to a recommended range, while paying close attention to what “feels” best for you.  Again, see Appendix J for a urine color to assess hydration levels and a chart outlining physical signs of dehydration.

Dr. Nessler is a practicing physical therapist with over 18 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment.  He is the developer of an athletic biomechanical analysis and author of a college textbook on this subject.  He serves as the National Director of Sports Medicine for Physiotherapy Associates, is a Safety Council Member for USA Cheer National Safety Council and associate editor of the International Journal of Athletic Therapy and Training. 

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[i] Guyton’s Textbook of Medical Physiology

 

[ii] Guyton’s Textbook of Medical Physiology

 

[iii] American Journal of Epidemiology in 2002

 

[iv] Walsh, R; Noakes, T; Hawley, J; Dennis, S. Impaired High-Intensity Cycling Performance Time at Low Levels of Dehydration, Int J Sports Med 1994; 15(7): 392-398