The Evidence for Increasing Cycling Endurance with Supplements
Lily Bedford looks at the role that various supplements can play in promoting cycling endurance.
Whether you are a professional athlete or a weekend warrior, as a distance cyclist, you will no doubt be interested in ways to maximise your endurance. While there are steps you can take towards this through modifying your dietary intake to ensure you have the optimal balance of carbohydrates and protein, adequate fluid on board, and a rich supply of performance-enhancing micronutrients, there is a lot of interest around the role that various supplements can play in promoting cycling endurance. However, as clinical studies show, some of these are more effective than others. Here we review some of the recent scientific literature that relates to the nutritional components of supplements and which may be of benefit to endurance cyclists.
Considering carbohydrate and protein
As carbohydrates provide the fuel for activity, supplements containing these offer an advantage to cyclists going a distance. However, there is some debate as to whether a supplement containing just carbohydrate is enough and the optimal form in which the carbohydrate should be supplied. Researchers at California State University considered whether an isocaloric carbohydrate supplement or one that also contained protein had a greater impact on the time taken to reach exhaustion while cycling, with their findings published in the Journal of Strength and Conditioning Research. Their results showed that while both types of supplements were able to extend the time until exhaustion was reached, there was no significant difference between the benefits they offered.
They are considering that carbohydrate supplements can be sufficient to sustain muscle activity. At the same time, glucose is frequently present in these, and galactose (which is a slower release carbohydrate) may provide sustained energy release for cyclists. However, a study reported in the International Journal of Sport Nutrition and Exercise Metabolism in 2012 demonstrated that when presented with a galactose-containing supplement, the performance time of cyclists taking these are no better than those using a glucose and maltodextrin supplement. Even if the presence of protein is not vital to aid cycling performance, work has been conducted to determine whether specific amino acids within sports supplements confer an advantage.
While scientists at the University of Tasmania did not find that the non-essential amino acid beta-alanine offered any benefit for trained cyclists achieving a greater power output, improved high-intensity endurance performance was achieved with a carbohydrate supplement containing leucine.
It has been suggested that the consumption of additional sodium may aid performance during cycling. In theory, this might relate to sodium's ability to maintain the volume of plasma, which is reduced during exercise due to the movement of fluid into the tissues and through sweating; without correction, this results in a concentration of the red blood cells which force the heart to work. Alternatively, it would help to prevent that reduction of sodium in the blood that occurs with intense exercise, which impairs muscle function owing to sodium's role within cell membrane transport and nerve function. The results of scientific studies have been conflicting about whether consuming extra sodium benefits endurance.
A well-designed study published in the Journal of the International Society of Sports Nutrition conducted by a team of researchers in New Zealand recently considered this with participants undertaking a 72km road cycle in cool conditions (under 16°C). They found that there was no significant difference in time trial performance or the blood sodium concentration between those who received a salt supplement and a placebo. While those taking the extra salt did experience a considerable increase in plasma volume, this didn't enhance their cycling ability.
This demonstrates that in cooler conditions where sweating and sodium losses are less of a problem, salt supplements are not necessary to boost performance in the saddle.
Although carbohydrate, protein, and salts might be the most common components of nutritional supplements for endurance sports performance, more novel ingredients have also been researched. One of these is a nitrate, which has been shown to increase tolerance to high-intensity activity, which can aid endurance.
Researchers in The Netherlands investigated the effect of nitrate from beetroot juice on the athletic performance of cyclists by studying their efforts in a time trial. After consuming the beetroot juice, or that with the nitrate removed, for six days, participants performed an hour of submaximal activity and then a timed 10km cycle. Both power output and their trial time were more favourable after the nitrate-containing beetroot supplement.
One way in which nitrate may be of benefit is through its conversion back into nitric oxide, which is a vasodilator, helping to improve the circulation and not only the supply of glucose and oxygen to the muscles for respiration, but also the removal of waste products, including lactic acid. This is advantageous as if it is allowed to build up, lactic acid can cause the muscles to tire and hinder their ability to work.
Supplements containing GlycoCarn, which promotes nitric oxide levels in the blood, are already available to improve an athlete's staying power, and therefore may be of interest to cyclists.
While these studies show some positive findings, further research is still required to clear up some of the uncertainties surrounding which supplements offer the most benefit in terms of increasing someone's endurance and is something that keen cyclists are bound to follow with interest.
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About the Author
Lily Bedford is a freelance writer.