Everyone who lifts weights with any degree of intensity will feel a burning sensation in the exercised muscles. This burn results from the buildup of lactic acid in muscle, which, in turn, is caused by the anaerobic nature of weight training. The lack-of-oxygen characteristic
of high-intensity weight training leads to the metabolic dead-end street of lactic acid.
Recent research shows that it's the acid part of lactic acid that causes muscle fatigue. Disassociated lactate, or lactic acid minus the acidic hydrogen ion, recirculates to the liver, where it's converted to glucose. The glucose then returns to the muscle via the blood as a reusable energy source. This system is called the lactate shuttle. Scientists now believe that there are two possible reasons why the hydrogen ions that accrue in muscle from anaerobic exercise cause muscle failure: 1) They interfere with the breakdown of glycogen to glucose in muscle by inhibiting intramuscular enzymes; and 2) they disrupt intramuscular calcium transport, which is necessary for muscular contraction. To counter this acid buildup in muscle, scientists began giving sodium bicarbonate, or common baking soda, to athletes more than 60 years ago.
Bicarb is a natural blood buffer that maintains the slightly alkaline composition of blood. In various studies over the years researchers found that the best conditions for sodium bicarb loading occurred when the subjects were trained; when the study involved repeated short-interval, high-intensity exercise; when the dosage was 300 milligrams of bicarb per kilogram (2.2 pounds) of bodyweight and when the subjects took bicarb 90 minutes to two hours before activity.
Under these circumstances the research showed improved performance from supplemental bicarb loading in sports such as rowing, cycling, running and swimming. Until recently however, there were no studies that specifically looked at the effects of bicarb loading on weight training. To test this, researchers from Auburn University in Alabama examined the effects of a standard loading dose of sodium bicarb on six weight-trained men. The study used a double-blind protocol involving a placebo group that took a similar-appearing but inert substance. This type of study is considered to be the gold standard among reputable researchers.
The men ingested 300 milligrams of sodium bicarb per kilogram of bodyweight 105 minutes before engaging in an exercise session that consisted of four sets of 12 reps, plus a fifth set to failure, on a leg press machine that was loaded to 70 percent of the subjects' one-rep maximums. This level of exercise intensity is comparable to an average bodybuilding workout.
Although the authors of the study concluded that the bicarb group showed no statistically significant improvement over the placebo group, four of the six men in the group increased their performances by an average of three repetitions, a 16 percent improvement. Although it is purely speculative,' the researchers noted, "it is possible that some individuals maybe more responsive than others to sodium bicarb ingestion." Despite this observation, the authors of this study stated that weight training isn't enhanced by bicarb loading.
They suggested that future studies should use a greater number of subjects and look at the effects of bicarb after exercise performed to exhaustion. In another study that examined the effects of bicarb supplementation, researchers from Applachian State University in North Carolina came to a different conclusion, however. In this case the subjects performed sets of 10 reps with 87.5 percent of their one-rep maximums on the leg press, and the results did indicate that bicarb increases the number of reps an athlete can do in a weight-training exercise.
While the results from these two studies appear to be contradictory, recall that the researchers in the first study that some people are more responsive to bicarb than others. To take their point a little further, some people may also be more sensitive to the side effects of a loading dose of bicarb, which can include bloating, abdominal pain, nausea and explosive diarrhea. Drinking a liter of water with the bicarb may help prevent these undesirable effects.