I changed classes and time today. I simply decided to go to the gym for a workout at a totally different time and participated in a different Instructor’s Spinning class. The Instructor, Karen Henry, was fabulous, but her class had predominantly hill climbing and some sprint sessions – quite different to the other sessions I attend regularly. Wow, what a lactic session it was.
A shaky start
Lactic acid has a bad reputation. Many people blame it for fatigue, sore muscles, and cramps. They think of it as a waste product that should be avoided at all cost. Guess what? Scientists have discovered that lactic acid plays a critical role in generating energy during exercise. Far from being the bad boy of metabolism, lactic acid provides fuels for many tissues, helps use dietary carbohydrates, and serves as fuel for liver production of glucose and glycogen. In fact, lactic acid is nature’s way of helping you survive stressful situations.
But what is Lactic Acid?
Technically, lactic acid is a chemical compound produced from pyruvate, an organic acid in animals. Pyruvate becomes lactic acid during normal metabolism, but also through exercise. (Lactic acid also can be found in some sour milk products, such as yogurt, kefir, and some types of cottage cheese.)
When you exercise, your body burns sugar, fat or protein along with oxygen. This produces the energy needed to continue exercising. When you exercise so intensely your muscles can’t get enough oxygen, pyruvate becomes lactic acid, which begins to build up in the muscle tissue.
You may be asking right now, what’s that got to do with me?
Well, previously, it was believed that lactic acid made the muscles more acidic, causing them to hurt and burn and interfering with their ability to contract. Actually, muscle tissue filled with lactic acid tends to contract more efficiently.
It is an extremely fast fuel that’s preferred by the heart and muscles during exercise. Lactate is vital for ensuring that your body gets a steady supply of carbohydrates, even during exercise that lasts for many hours. Lactate is so valuable, that taking it as part of a fluid replacement drink before, during, or after exercise improves performance and speeds recovery.
As the University of Toronto’s Melissa de Souza writes in her paper “Lactic Acid: Friend or Foe,” there is no evidence that lactic acid causes muscle fatigue, only that it serves as a marker of muscle fatigue.
De Souza notes a study in which rats were infused with lactate: the result was an increased endurance of muscle contraction, as well as increased excitability of the muscle fibers.
In humans, she notes, “performing a bout of heavy exercise before exhaustive aerobic exercise increased the blood lactate concentration prior to the second bout of exercise, and this lactate accumulation was associated with longer exercise times.”
Instead of fatiguing muscles, de Souza concludes, lactic acid “primes the muscle to perform better and for longer periods of time before fatigue.”
Who’s for a better, more intense workout? Who’s for increased energy levels and less fatigue?
Many experts now indicate that lactic acid generation is a key not only in improving muscle mass but in all aspects of exercise. An essay by the Cory Holly Institute notes that “scientists now recognize lactic acid as a major player in the way our bodies generate energy during exercise. Lactic acid is actually our friend.”
4 Things You Should Know About Lactic Acid
1. Lactic acid doesn’t cause muscle soreness and cramps. Delayed onset muscle soreness, the achy sensation in your muscles the day after a tough workout, is caused by muscle damage and post-exercise tissue inflammation.
2. The body produces lactic acid whenever it breaks down carbohydrates for energy. The faster you break down glucose and glycogen the greater the formation of lactic acid. At rest and sub- maximal exercise, the body relies mainly on fats for fuel. However, when you reach 50% of maximum capacity, the threshold intensity for most recreational exercise programs, the body “crosses over” and used increasingly more carbohydrates to fuel exercise. The more you use carbohydrates as fuel, the more lactic acid you produce.
3. The heart, slow-twitch muscle fibers, and breathing muscles prefer lactate as a fuel during exercise. In the heart, for example, the uptake of lactate increases many fold as the intensity of exercise increases while uptake of glucose remains unchanged. These tissues suck up lactate at a fast rate to satisfy their energy needs.
4. Lactic acid is a very fast fuel that can be used to athletes’ advantage during exercise. Including lactate as part of a fluid replacement beverage provides a rapid fuel that can help provide energy during intense exercise. The rationale for including lactate in athletic drinks is simple- since the body breaks down so much of dietary carbohydrates to lactate anyway, why not start with lactate in the first place? Lactate in the drink can be used rapidly by most tissues in the body and serves as readily available building blocks for restoring liver glycogen during recovery.
Much of this information was helpfully provided by Dr Marc Dussault of Exponential Programs.
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