Feel the burn?If you’ve experienced the unpleasant feeling that your muscles are on fire during a hard-charging workout, you are most certainly not alone. It’s a particular kind of discomfort that you’ll never forget – and, in turn, will have you looking for ways to tame the flame. Many endurance athletes seek out ways to combat lactic acid buildup, and the promise of supplements to do just that can be enticing. But do they work? Let’s look at the science.
“Lactic acid buildup,” “lactate threshold” – what does that even mean?
When you exercise, your body uses oxygen to break down glucose for energy. But during more intense bouts of physical activity (hello, intervals), the working body can make use of the substrate lactate to also generate energy (ATP) within the mitochondria. In the liver, lactate can be used to produce glucose via gluconeogenesis allowing more of this sugar to be employed to generate the energy needed for muscular contraction, especially when oxygen availability is limited. It’s estimated that roughly 75% of lactate produced inside the muscle cells is recycled into glucose and used as fuel. That makes lactate a potentially vital substrate for energy production during exercise to allow athletes to keep up the pace. Worth noting is that physical training renders more efficient lactate utilization by the muscles. Contrary to popular thought, lactate can be produced and used in aerobic as well as anaerobic scenarios.
And through improved sports physiology research we now know that lactic acid, the joining of lactate with a hydrogen ion, is not the primary driver of muscular burn during exercise and resulting fatigue. (As we mentioned, lactate helps delay muscular fatigue, rather than causing it.) Instead, when ATP is broken down for energy production there is the release of hydrogen ions leading to a rise in acidity within muscular tissue and the dreaded burn. So with more ATP catabolism to meet the increased energy demands of a body in motion, there is likely to be more burning sensation. A scenario most likely to occur in cases where your muscles cannot rely on oxygen to produce enough ATP and therefore they need to make a switch to another pathway – anaerobic metabolism – to produce more ATP. And a major byproduct of the anaerobic pathway is hydrogen ions that can tilt the muscle acid-base balance towards the former.
If the pH goes too low, an athlete will likely be forced to scale back their effort. For some people, this may even lead to feelings of nausea, definitely not conducive to a PR pursuit. Keep in mind that muscular acidosis is just one of many scenarios that can contribute to exercise fatigue, which includes glycogen depletion and psychological factors.
So it does not make much sense when athletes say they are training to improve their “lactate threshold”, when in fact lactate is something to celebrate. And let’s finally put to bed the idea that you need to flush lactate out of your muscles after a workout to help reduce muscle soreness. The reality is that muscle soreness after exercise occurs due to microdamage to muscle fibers, and not the accumulation of lactate. So lactate has and continues to be blamed for workout crimes it has not committed.
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Still, there might be ways through certain supplementation that athletes can lower their susceptibility to acid build-up during boots of intense workout, even if it has nothing to do with lactate. This may lead to improvements in performance and, quite simply, gleaning more joy from working up a sweat.
These two items might help you drop acid, so to speak.
Supplements to manage acid build-up during exercise
Most commonly known as baking soda, sodium bicarbonate (NaHCO3) is a mildly alkaline salt made up of sodium and bicarbonate ions.
According to a position stand from the International Society of Sports Nutrition based on the best available evidence, supplementing with sodium bicarbonate before muscular endurance activities such as high-intensity cycling, running and swimming can improve performance in both men and women, especially when intense efforts last 30 seconds to 12 minutes. Another study review published in the journal Sports Medicine also found enough data to support the belief that sodium bicarbonate usage can enhance muscular endurance in both small and large muscles. Much of its benefits may occur near the end of an endurance workout, which may help with a final “push” to the line.
How does it help? Sodium bicarbonate is considered a buffering agent to prevent the pH within your muscle fibers from dropping as quickly during intense exercise. In theory, this could help someone push harder for longer to give them a winning edge. During exercise, bicarbonate and other buffering agents in the body work to pull the excess hydrogen created during ATP breakdown out of the working muscle and into the bloodstream, allowing the muscle to return to a less acidic state and, in turn, increasing the time to exhaustion. This recent meta-analysis in the Journal of the International Society of Sports Nutrition found sodium bicarbonate supplementation can indeed have a positive impact on pH levels in the muscle via improvements in the anaerobic metabolism system. This benefit may also lower the perceived effort of exercise. Not to be overlooked is that a portion of the ergogenic effect of sodium bicarbonate usage seems to come down to the always reliable placebo effect. You think a shot of baking soda will help you crank up that killer incline, so it enviably does.
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It does appear that higher intensity, shorter duration efforts benefit most from sodium bicarbonate use. All-out sprint efforts and HIIT workouts are good candidates for a pre-workout dose of baking soda. On the flipside, a level 1 run or bike ride won’t likely benefit as the intensity is not high enough to cause a noticeable rise in muscle acidity.
A dose of 0.3 g/kg of body weight taken 60 and 180 min before exercise or competition seems to be the sweet spot that provides an ergogenic benefit with less risk of adverse side-effects including bloating, nausea and stomach pain. Taking your sodium bicarbonate with a high-carbohydrate meal, and in enteric-coated capsules are possible strategies to minimize any side-effects. Some people will simply dissolve the necessary amount of sodium bicarbonate in warm water and send it down the hatch. For multiple-day protocols, a total sodium bicarbonate dose of 0.4 or 0.5 g/kg per day for 3 to 7 days before a big workout also produces ergogenic effects. A smart way to do this is to divide the total daily dose into smaller doses, ingested at multiple points throughout the day (eg, 0.1 to 0.2 g/kg of sodium bicarbonate consumed at breakfast, lunch, and dinner). The benefit of multiple-day protocols is that they could help reduce the risk of side-effects on the day of competition. A mid-race port-a-potty run is never enjoyable.
Beta-alanine is a non-essential amino acid that is produced endogenously in the liver, but can also be obtained in various foods including poultry and beef. Its potential impact on bolstering exercise performance stems from the vital role it plays in the production of carnosine within our muscles. The rate-limiting factor of carnosine synthesis in the human body is beta-alanine availability. Since carnosine is known to function as a buffer against acid accumulation in working muscles higher levels derived from beta-alanine supplementation, in theory, should allow you to push harder with less of the burn that can lead to fatigue and wanting to tap out. Supplementing with beta-alanine has been shown to elevate carnosine levels in muscles by up to 80% after 10-weeks of use.
To date, there is enough scientific literature to say with a certain degree of confidence that taking beta-alanine can be a viable method for lowering intramuscular acidosis and, in turn, muscular fatigue caused by a build-up of acid. But, as with sodium bicarbonate, its impact is more felt during activities where there are high rates of anaerobic energy delivery such as shorter duration max-effort sprints. So it could be beneficial for helping to increase your work capacity and the time it takes for exhaustion and perceived fatigue to set in for instances where acidosis is a limiting factor such as taking on shorter inclines lasting 1 to 4 minutes or if you need to pick up the pace for a few minutes during a race. Running or riding at a party pace likely won’t derive much benefit from the use of beta-alanine.
The amount of beta-alanine administered in most studies ranges from 4 – 6 g in divided daily doses that are taken for several consecutive days. It’s less likely to have the same degree of impact if just taken once before a hard workout. Cosistent use is key. Many pre-workout supplement formulations contain beta-alanine, but in many cases the levels may not be adequate to help you beat the burn. Combining sodium bicarbonate with beta-alanine may produce additive effects on exercise performance.
Levels of muscle carnosine can vary among people – it’s often lower in vegetarians and vegans who don’t consume it from meats as well as women and older individuals. There is always the chance that people starting with lower baseline levels of carnosine in their muscles would benefit the most from beta-alanine supplementation.
Matthew Kadey, MS, RD, is an author and journalist who specializes in sports nutrition and is the recipient of the 2013 James Beard Award for Food Journalism.
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