Things to know about lactic acid:
(c/o CSU...and a Loma Linda U grad student)
1. Lactic acid is formed from the breakdown of good ol sugar. The blood sugar (glucose) provides the fuel for the chemical reactions. When the body produces (process called anaerobic metabolism) the hydrogen ions that make up the acid, it satisfies our energy 'instant' exercise intensity requirements.
2. When muscles ache after a workout it is caused by inflammation of the tissue muscles and muscle damage, and if over-excited, muscle fatigue. (ie not be able to even lift your arms!) This old bad body prefers to use
use hot showers and massage as relaxation techniques to relieve aches and soreness.
3. Whenever the body needs energy, it breaks down carbohydrates. When carbo's are used, acid is produced. The faster the body breaks down glucose and glycogen, more lactic acid is formed. While this old bad body is on the couch, (or at rest), I am hoping the body is burning stored fat (wishful thinking). However, there is a point where the fat burning is reduced, and the burning of carbo's kicks in. With higher intensity workouts (running to the refrigerator) more carbohydrates are necessary, and with more burned carbo, more lactic acid is produced.
4. Remember those fast-twitch muscles that us old timers stopped using eons ago? As I run from the refrigerator back to the couch, those fast twitch muscle fibers use more oxygen, burn more carbo's, and form more lactic acid.
Increased lactic acid in the blood stream means the rate produced exceeds the removal rate.
5. Blood levels of lactic acid reflect the balance between lactic acid production and use.
Thus acid production is directly proportional to carbos used to supply energy to the tissues. Rapid use of carbos for fuel, such as during intense exercise, accelerates producton. Slowing down the pace of exercise or stopping exercise altogether, the rate of lactate used for energy catches up and balances the rate of lactate production.
Dr. George Brooks, at UC Berkeley, described the theory as "Lactate Shuttle Theory."
Kinda like a country 2 step, if you know what I mean.
6. Lactic acid then, is as a chemical "fidler - middleman" for metabolizing carbos.
Carbo's enter the blood from the intestines to the liver as blood sugar. Instead of entering the liver as glucose and being converted directly to glycogen, most glucose from dietary carbos bypasses the liver to reach muscles before converting to acid.
To complete the dance cycle, the acid returns to the blood, back to the liver, and makes glycogen. The liver produces glycogen indirectly from lactic acid rather than directly from blood glucose.
Dr. McGarry calls that theory: the "Glucose Paradox" reveals significance lactic acid in carbo metabolism.
7. Remembering that, any bad bod's capacity to produce lactic acid tries to match the ability to use it as fuel. Hence, just getting up off the couch there is a tremendous increase in the rates required for muscle uptake, glucose use and breakdown of glycogen.
Getting back to the couch is much easier then? Yep! Blood lactic acid levels stabilize even though lactic acid production increases, and thus ready and prepared for relief. Ever hear of the proverbial, he got his "second wind".
8. The cardiovascular geniuses tell me my broken heart, very very slow-twitch muscle fibers, and asthma induced breathing muscles prefer lactate as a fuel.
During exercise, (just started walking everyday about three months ago) my heart use of lactate increases as walking intensity increases and (hopefully) the glucose burn remains unchanged. These tissues suck up lactate at a fast rate to satisfy their energy needs.
9. As the country 2 step turns to rock and roll, a very fast fuel is needed. Thus
both glucose and lactic acid rise in the blood after a carbohydrate-rich meal (remember the retired baseball pro eating chicken before baseball games?). Using lactic acid as a carbo "middleman" helps rid of carbos, without increasing insulin. During exercise, you won't want an increase in insulin because it decreases the availability of carbohydrates that are vital to high performance metabolism.
10. Why is lactic acid so important in metabolic regulation?
Our genuises tell me it remains unknown.
Including lactate as part of a replacement beverage provides a rapid fuel that can help provide energy during intense exercise.
Since my body breaks down so much carbos to lactate, why not start with lactate in the first place? Good question!
11. Training programs have been shown and proven to improve and aid lactic acid removal from my aging muscles. Of course it's the younger Docs that tell me higher intensity intervals and walking more and more distances allows me to understand and effectively learn about lactic acid.
Lactic acid formation and removal rates increase as I jump from the couch, run to the refrigerator, and back to the couch faster and more often.
Training with a lots of lactic acid will then excite this bad body and produce the enzymes to speed up lactic acid use.
Over training causes muscular adaptations that speed the rate of lactate removal. Something about mitochondrial capacity, {which I have not figure out yet, much less spell or pronounce], uses fatty acids as fuel, which decreases lactate formation.
Summary
A. Fuel for the body during rest and exercise is very important.
B. Lactid Acid is used to produce liver glycogen. This is a most important energy sources.
C. Lactate is the recommended fuel source in heart muscle and slow-twitch skeletal muscle fibers.
D. Lactic acid is an acid. Thus accumulation cause distress and fatigue.
E. Higher intensity training improves the capacity to use lactic acid as a fuel during exercise and recovery and to develop cardio capacity, that also reduces lactic acid transport to tissues.
F. Distance training causes tissue enzymes to increase use of fatty acids for energy. This helps slow lactic acid production from carbo and enhances muscle tissues's ability to use lactic acid as fuel.
G. Honey, have you seen my slippers? And can you get me another beer for more carbo's.
cheers,
Bear
References
Brooks G.A., Fahey T.D., White T. Exercise Physiology: Human Bioenergetics and Its Applications. Mt. View, CA: Mayfield Publishing Co., 1985.
Brooks, G.A. Lactate production under fully aerobic conditions. The lactate shuttle during rest and exercise. Fed. Proc. 45: 2924-2929, 1986.
Brooks, G.A. Mammalian fuel utilization during sustained exercise. Comp. Biochem. Physiol. 120: 89-107, 1998.
Brooks, G.A., Mercier J. The balance of carbohydrate and lipid utilization during exercise: the crossover concept (brief review). J. Appl. Physiol. 80: 2253-2261, 1994.
Brooks, G.A. and Trimmer J.K. Glucose kinetics during high-intensity exercise and the crossover concept. J. Appl. Physiol. 80: 1073-1074, 1996.
Donovan C.M., Brooks G.A. Endurance training affects lactate clearance, not lactate production. Am. J. Physiol. 244: E83-E92, 1983.
Hultman E.A. Fuel selection muscle fiber. Proc. Nutr. Soc. 54: 107-121, 1995.
Ahlborg G., Felig P. Lactate and glucose exchange across the forearm, legs and splanchnic bed during and after prolonged leg exercise. J. Clin. Invest. 69: 45-54. 1982.
Ahlborg G., Wahren J., Felig R. Splanchnic and peripheral glucose and lactate metabolism during and after prolonged arm exercise. J. Clin. Invest. 77: 690-699, 1986.
Zinker B.A., Wilson R.D., Wasserman D.H. Interaction of decreased arterial PO2 and exercise on carbohydrate metabolism in the dog. Am. J. Physiol. 269: E409-E417, 1995.
ps. Before a pitcher has (heaven forbid) arm injury, he may elect, at times, NOT to use ice (if only mildly tender). After suffering through either major or minor arm injury (and rehab), pitchers use 20 min of ice (and typically after a day's work...(ie After mound work, then run not vice versa). Pitch count's got nothing to do with the proper use of ice! Leo Mazzone (if you like Italian food), tells me, in his observations, it's over-exertion and over-extension that increases risk of arm injuries. I can understand that!