the science behind pH and performance part 2

Posted: Friday, 16 March 2012 by Strength&Nutrition24/7 in Labels: , , ,
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pH scale:
            
The acidity and alkalinity of a solution is represented through a scale, which extends form 0-14. The scale is based upon the concentration of H+ in moles per liter. The midpoint of the scale is 7 where the concentrations of H+ and OH- are equal (pure water). When a solution has a greater amount of H+ then OH- it is an acidic solution with the pH being below 7. When a solution has less H+ then OH- it is an alkaline solution with the pH being above 7.




Figure 1
Blood and Muscle pH:

The chemical reactions that occur in the body can have a huge affect on the body’s function-ability. Due to this, the body is extremely careful in maintaining its pH in very narrow limits (Tortora G.J., 2009). If any deviation occurs from these narrow limits the body’s functions are greatly disrupted and can cause issues with health and performance (Alex McDonald; Robert Burns; & Tortora G.J., 2009). The pH of fluids throughout the body differ, yet are all kept within their narrow ranges. The body attempts to keep the pH level between 7.35 and 7.45, this is just slightly more alkaline than pure water (7) (Tortora G.J., 2009; Powers S. K., 2007). When ones blood pH falls below 7.35 it results in a condition known as acidosis, and if pH goes above 7.45 one has a condition called alkalosis (Tortora G.J., 2009). These two conditions can have detrimental effects on a person’s body. Muscle pH in resting individuals is approximately 6.9(Powers S. K, 2007, & Hermansen L., 1972).


Figure 2
Acidosis:
Acidosis is when the blood ph drops below 7.35. When acidosis occurs, serious physiological effects occur such as the depression of the central nervous system through depression of the synaptic transmissions (Tortora G.J., 2009; & Dr. Ben Kim). The further the pH drops the more sever the depression of the central nervous system and the side effects associated; if the pH drops below 7 the person may become disoriented, comatose, and even die (Tortora G.J., 2009; & Ben Kim).  When someone goes into a coma due to extreme acidosis, the general outcome is death (Tortora G.J., 2009).  

Figure 3
Alkalosis
Alkalosis is a condition in which blood ph is above 7.45 (Tortora G.J., 2009; Powers S.K., 2007; & Ben Kim). In contrast to acidosis, alkalosis causes over excitation of the central and peripheral nerves (Tortora G.J., 2009; &  Ben Kim). The neurons begin to conduct impulses repeatedly, even when you are not sending normal stimuli, the results are nervousness, muscle spasms, and convulsion and death in extreme cases (Tortora G.J., 2009).  
Athletes who desire to improve themselves, reduce fatigue, and compress recovery time need to have an understanding of pH balance and the negative impact pH imbalances can cause (McDevitt L., 2011; McDonal, Alex; & Burns Robert).  Elite athletes, particularly those involved in high intensity anaerobic activity for greater than 45 seconds should be concerned with maintaining a healthy pH balance (Powers S.K., 2007; Hermansen L., 1972; Maughan R.J, 1997; & Greenhaff, 1988). These athletes need to understand this concept, since they will regularly place themselves under physical and dietary stress that can lead to pH imbalances, most commonly lactic acid, which can cause hydrogen ion buildup (Powers S.K., 2007; Hermansen L., 1972; Maughan R.J, 1997; & Greenhaff, 1988; Overgaard, 2006; & Steve Bird, 2011). Simply put, “whatever your level of athletic intensity, a healthy pH balance can mean the difference between greater athletic achievement and being brought up short by muscle burn (Burns R.).”
H+ production during exercise: (Powers, 2007 was used as reference for this section)
First we must consider volatile acids. For example, carbon dioxide (CO2).  CO2 Is an end product in the metabolism of carbohydrates, fats, and proteins. CO2 itself may not be an acid, but it can be regarded as acid due to its ability to react with water and produce carbonic acid which then dissociates to form H+ and H2CO3. Throughout day to day life, one produces CO2 and the body eliminates it by means of the lungs. However, when one is performing exercise, the rate at which CO2 is often eliminated is not as great as it is being produce and therefore adds an additional volatile acid load on the body.
The infamously famous lactic acid. Lactic acid and acetoacetic acid are known as organic acids. These acids are produced through the metabolism of carbohydrates and fats. Under normal resting conditions these have little effect on the bodies pH balance. However, when one participates in intense exercise (lactic threshold) the pH of the bodies fluids are greatly affected. The Bodies pH can be affected so significantly that the body may find itself in acidosis. As previously noted when the body finds itself in acidosis, depression of the central nervous system through depression of the synaptic transmissions occurs; when the nervous system is depressed one will not be able excite the muscles as well and therefore lose strength, and power.

Figure 4


Lactic acid production fast glycolysis:
When considering the significance in intensity of training for greater than 45 seconds to have an effect on pH level, one must understand how lactic acid is produced. During the time frame of 30seconds-3minutes glycolysis is the dominant ATP production system. During this process glycolysis breakdown of carbohydrates has been supplied by either glucose in the muscle or delivered in the blood to resynthesize ATP. This process use has a multitude of reactions that occur and therefore the resynthesis of ATP through glycolysis is slower than the phosphagen system. At the end of glycolysis Pyruvate is the product. Pyruvate has two options in its fate. It can either be converted to lactate or shuttled in to the mitochondria. If oxygen is scarce as found in anaerobic conditions, pyruvic acid is reduced through fast glycolysis which produces lactic acid.



Figure 5        
Lactic Threshold:
In high intensity exercise, lactic acid levels rise in an exponential fashion. The blood lactate levels do not rise very rapidly when one is at rest or below 50% VO2 max in untrained individuals and 65%-80% VO2 max in trained athletes (Gollnick, 1985; & Powers, 2007). However, once one exceeds these percentages, the rate at which blood lactate increases is astronomical. The point at which the blood lactate level begins to rise represents the point in which reliance on the anaerobic system increases (Davis, 1985; Wasserman, 1986; Wasserman, 1964; Wasserman, 1973; & Powers, 2007). 


Figure 6


How much of an effect does exercise have on pH:
When one is performing exercise at a high intensity, with large muscle groups, and adequate duration, one can make significant changes to blood and muscle pH levels. In the case of leg work, it has been found to be capable of reducing blood pH from 7.4 to 7 and muscle pH from 6.9 to 6.4 within a few minutes (Hermansen, 1972; & Itoh, 1991). PH can be further reduced by doing repeated bouts of this form of exercise. The lowest pH ever recorded was done through this method with a pH of 6.8 (Jones, 1977; Linderman, 1990; Rogbergs, 1990; & Street, 2001). This level of pH would be life threatening if left untreated for several minutes (Powers, 2007).

Figure 7 Changes in blood pH and muscle ph during incremental exercise
Figure 8 changes in blood concentration of lactic acid, bicarbonate, and ph as a function of work rate


Supplement Buffering:
Once the acid-bace balance was found to have an effect on muscle fatigue and impaired sport performance, many studies have explored the possibility that ingestion of a sodium buffer could improve athletic performance. The majority of studies found that by supplementing with a sodium buffer before exercise would improve performance (Requena, 2005; Coombes, 1993; Costill, 1994; Linderman, 1991; Neilson, 2002; & Robertson, 1987). However, not all studies agreed (Aschenback, 2000; Requena, 2005; & Cameron, 2010). Two buffers have been studied in particular sodium bicarbonate and sodium citate. The general results involved with supplementing with these is increasing the blood buffering capacity and intern improves performance, by increasing the transport of lactate and hydrogen out of the muscle (Roth, 1990).


In deciding whether to implement this into your  plan you should understand the risks, side effect, and possible consequences. When using sodium bicarbonate it can cause severe abdominal discomfort including diarrhea and vomiting (Costill, 1984; Robertson, 1987).  However, in the case of sodium citrate, it has been found to improve performance without the side effects associated with sodium bicarbonate (Kowalchuck, J et al. 1989; & McNaughton, 1990) . Besides these side effects, one must be weary of severe alkalosis. The final concern is that many sport regulatory agencies have banned the use of sodium buffers during competition.
Beta- alanine is a supplement that has made waves in the performance world recently. Beta –alanine is a non-essential amino acid that is common in foods, especially meats. The significance of beta-alanine is too due with it being the rate limiting substrate for synthesis of carnosine, which is an important intracellular buffer (Harris, 2006; & Antonio, 2008). Carnosine is important due to its ability to buffer accumulated hydrogen ions (Dunnet, 1999; Harris, 2006; Hill, 2007; Tipton, 2007; Campbell, 2010; Van Thienen, 2009, & Antonio, 2008). To obtain these aforementioned benefits of carnosine, it would seem logical to simply ingest supplemental carnosine (Antonio, 2006). However, when consumed orally in humans, carnosine is rapidly hydrolyzed in blood plasma by the enzyme carnosinase (Dunnet, 1999; Harris, 2006; Hill, 2007; Tipton, 2007; Campbell, 2010; Van Thienen, 2009, & Antonio, 2008). Independent ingestion of beta-alanine and histidine allows these 2 molecules to be transported into the skeletal muscle and be resynthesized into carnosine (Dunnet, 1999; Harris, 2006; Hill, 2007; Tipton, 2007; Campbell, 2010; Van Thienen, 2009, & Antonio, 2008). It appears that beta-alanine is the amino acid that influences intramuscular carnosine levels the most (Antonio, 2006).


Conclusion


            The body is designed to function within a strict acid-base relationship through out the body. The body attempts to do everything it can to avoid falling outside of these prime zones. However, when one trains in the fast glycolysis, the body is incapable of keeping up with change in acidity. As the acidity increases and the body falls further into acidosis the greater the depression of the central nervous system. With the central nervous system being depressed, the body is unable to function at optimal levels and will not be able to excite the muscles as well. Fortunately, the battle with pH levels and performance are not completely lost, one can improve their lactic threshold, supplement to buffer, and increase lactic tolerance. 


Please leave comments below with all your questions and opinions


Part 1 


References

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Figures

  • Figure 1 Retrieved from http://www.abundanthealthcenter.com/blog/the-acid-alkaline-ph-scale/
  • Figure 2 Powers Powers, S. K., & Howley, E. T. (2007). Exercise physiology: theory and application to fitness and performance (6th ed.). Boston: McGraw-Hill. 231
  • Figure 3 Powers, S. K., & Howley, E. T. (2007). Exercise physiology: theory and application to fitness and performance (6th ed.). Boston: McGraw-Hill. 232
  • Figure 4 Powers, S. K., & Howley, E. T. (2007). Exercise physiology: theory and application to fitness and performance (6th ed.). Boston: McGraw-Hill. 234
  • Figure 5 Baechle, T. R., & Earle, R. W. (2008). Essentials of strength training and conditioning (3rd ed.). Champaign, IL: Human Kinetics. 25
  • Figure 6 Powers, S. K., & Howley, E. T. (2007). Exercise physiology: theory and application to fitness and performance (6th ed.). Boston: McGraw-Hill. 259
  • Figure 7 Powers, S. K., & Howley, E. T. (2007). Exercise physiology: theory and application to fitness and performance (6th ed.). Boston: McGraw-Hill.237
  • Figure 8 Powers, S. K., & Howley, E. T. (2007). Exercise physiology: theory and application to fitness and performance (6

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