Anyone who’s lifted weights for any length of time knows that when you feel an intense burning sensation after a certain number of reps, the end of the set is near. Lactic acid was thought to be the cause of the muscle burn.
Lactic acid is a by-product of anaerobic metabolism, which refers to activity that uses mostly glucose and glycogen, as well as creatine and ATP, as primary energy sources. The term “anaerobic” denotes the lack of oxygen in the process, which isn’t entirely correct. Some oxygen is present—just not enough to prevent the accumulation of lactic acid in muscle.
Still, it isn’t the lactate acid that actually causes fatigue. Lactic acid dissociates into two discreet substances: lactate and hydrogen ions. Lactate is actually good stuff. It can be recycled in the blood and returned to the liver, where it’s converted back into glucose and then sent back to the working muscle as an energy source, a process known as the Cori cycle.
The actual source of the burning sensation you feel during an intense set is the hydrogen, broken off from the lactate. Hydrogen ions lower muscle and blood pH, raising acidity.
When the acidity level in muscle and blood exceeds the normal narrow range between acidity and alkalinity, muscle force production drops, and fatigue sets in rapidly. Muscle force drops because the high acidity in muscle produced by hydrogen ions inhibits calcium release, calcium that’s needed for muscle contraction.
The great amount of acidity also inhibits an interaction between the two primary muscle contractile proteins, actin and myosin, which further blunts muscle force and strength. As if that wasn’t enough, ATP, the most elemental source of cellular energy, cannot function in a low pH—that is, high-acid—environment. In effect, energy production in muscle is cut off by a high acidic environment.
The body has a number of built-in mechanisms that buffer, or neutralize, the excess acid that can build up. They include sodium bicarbonate, phosphates and other proteins. The primary extracellular buffer—meaning it works outside the cell—is sodium bicarbonate.
Sodium bicarb is such a potent buffer that scientists have experimented with using it to boost athletic prowess for more than 80 years. Those studies have varied in their results. One problem is that sodium bicarb cannot penetrate muscle cell membranes. So, if it can’t get into the muscle, how can it possibly aid workout efficiency?
The answer is that sodium bicarb buffers the hydrogen ions that leave the muscle and enter the blood, which leads to more hydrogen exiting the muscle and a lowering of intramuscular acid.
It appears that sodium bicarb stimulates the activity of a transporter within muscle that pushes the lactate and hydrogen out of the muscle and into the blood. There, the acid—the hydrogen—is buffered by sodium bicarb, which causes the hydrogen ions to break down into carbon dioxide and water, neutralizing the acidic effect. Sodium bicarb can neutralize about 62 percent of the hydrogen ions released into the blood during intensive exercise.
As noted, because of its potent buffering qualities, numerous studies have looked into whether sodium bicarb can be used to increase the effectiveness of exercise and boost athletic ability. Most have involved activities such as cycling, swimming and running. Some studies have noted significant improvement after supplementing with bicarb, while others have not. In those that did not, some didn’t use a sufficient dose, while in others the problem was that bicarb only works with glycolic metabolism.
Simply put, exercises lasting less than one minute may not produce enough lactic acid for sodium bicarb to work. The small amount produced during a typical set of bodybuilding exercise can be buffered effectively by the body’s own buffering mechanisms—including natural sodium bicarb production. That said, what happens after numerous sets—in, say, a typical bodybuilding workout?
One study published in 1993 did look at the effects of bicarb on a group of young men engaged in weight training. They did four sets of 12 reps on the leg press, using a weight equal to 70 percent of one-rep maximum. They rested 90 seconds between sets and did a fifth set to muscular failure to measure any performance increases.
Four of the six subjects were able to increase their rep counts after taking bicarb, but that wasn’t considered statistically significant. The authors noted that it wasn’t enough exercise to disturb the acid-base balance significantly, so the results weren’t apparent. The fact that the subjects rested 90 seconds also played a part in the outcome, as that much rest would give the body enough time to buffer any excess acid produced.
A 1998 study did boost the intensity level slightly; however, it wasn’t enough to resemble an actual bodybuilding workout. Despite that, seven out of 15 of the subjects were able to increase their reps after taking in sodium bicarb vs. a placebo.
Not surprisingly, sodium bicarb’s value as an ergogenic aid for bodybuilding purposes remained questionable. A recent study did take up the issue.1 The subjects were 12 resistance-trained men, average age, 20, who engaged in the following real-world bodybuilding leg workout:
1) Barbell squats, 4 x 12
2) Incline leg presses, 4 x 12
3) Leg extensions, 4 x 12
4) Leg extension performance test—done after the fourth set of leg extensions using 50 percent of one-rep max to muscle failure.
The men rested two minutes between exercises and 90 seconds between sets. The weight used was enough to allow them to reach muscular failure after 10 to 12 reps. An hour prior to training, the men took either a placebo or sodium bicarb, 300 milligrams per kilogram of bodyweight. The supplement was divided into four doses, consumed at 10-minute intervals. They also drank 1.6 liters of fluid. With the first two doses the men drank Gatorade, which included carbs and minerals. They also ate a bagel.
Getting some carbs and sufficient fluid reduces the common side effects of sodium bicarb. The high sodium content triggers an osmotic effect, bringing fluid into the gut to dilute the sodium. That can lead to gastrointestinal effects such as nausea and vomiting. By eating a small carb meal and getting enough fluid, you can block them.
Separating the bicarb into four small doses rather than one large one also lowers the chance of side effects, as does adding the small carb meal, which prevents the production of excess intestinal gas (think of Alka-Selzer, with its primary active ingredients of sodium bicarb and aspirin).
This study was the first to use an actual bodybuilding workout involving enough volume to perturb the acid-base balance, and the men did show a definite improvement in the workout after taking sodium bicarb compared to the placebo—they could do more reps without fatigue. The ability to complete more reps would boost training intensity, and that, in turn, would stimulate a greater degree of muscle hypertrophy.
One possible problem with taking in sodium bicarb prior to training: Some studies show that the higher acidity produced by intense training signals the release of anabolic hormones, mainly growth hormone. Indeed, a 1994 study showed that providing sodium bicarb prior to training did blunt growth hormone release—but it also blunted cortisol release.
Since cortisol, an adrenal steroid, is the primary catabolic hormone in the body, blunting it would have to be considered beneficial to muscle growth. Other studies, however, have not shown any correlation between higher acidity in the blood and GH release. Factors that may be involved in GH release during exercise include nitric oxide, neural stimulation and the release of catecholamines, mainly epinephrine and norepinephrine.
As discussed, sodium bicarb is an effective extracellular buffer, but is it synergistic with other buffering substances that work inside of muscle? One such intramuscular buffer is carnosine, an amino acid complex consisting of beta-alanine bound to histidine.
Recent studies show that combining beta-alanine, which is the rate-limiting production factor for the synthesis of carnosine in muscle, with sodium bicarb does in fact exert a synergistic effect, increasing buffering capacity even more. By using sodium bicarb as well as beta-alanine, you boost the buffering capacity both inside and outside of muscle.
Other studies show that combining sodium bicarb with creatine also boosts buffering capacity. Although creatine is well-known for its energy-producing effects in muscle, a lesser-known function is its ability to buffer excess acidity produced during exercise.
I suspect that combining all three—sodium bicarb, beta-alanine and creatine—would bring significant improvements in training intensity. A good protocol would be as follows:
1) Creatine: 5 grams taken an hour prior to training.
2) Beta-alanine: 3 to 6 grams in divided doses throughout the day, with the last dose an hour prior to training. To prevent side effects, take no more than 1.6 grams at a time.
3) Sodium bicarb: 300 milligrams, taken in divided doses of 120 milligrams per kilogram of bodyweight every 10 minutes, starting an hour prior to training, and consumed with about 300 milliliters of a carb drink containing no more than 6 to 8 percent carbs and a small carb meal. Be sure that the carb meal is not high in fiber so it’s easily digested. You can probably substitute a protein bar that contains at least 40 grams of carb. The branched-chain amino acids in the bar will also aid training intensity.
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1 Carr, B.M., et al. (2013). Sodium bicarbonate supplementation improves hypertrophy-type resistance exercise performance. Eur j Appl Physiol. 113;743-52.