Nitrate Supplements with Low-Oxygen Sprint Interval Training May Build Muscle Fiber, No Clue if it Affects Sports Performance

Sports Performance

A small study from Belgium has been released suggesting that the use of nitrate supplements alongside Sprint Interval Training (SIT) in low-oxygen conditions may be able to promote the growth of certain muscle fibers. Though mildly interesting, it’s important to keep in mind that whether this results in improved sports performance, or is even safe, remains to be seen.

In Brief: Nitrates

Nitrates are found in leafy, green foods like spinach. The nutrient is used for various functions in the human body, notably those that take place during periods of exercise. The researchers wanted to see if high-dose nitrate supplements, along with physical training in different conditions, could affect muscle growth.

The Study

There were 27 moderately-trained participants for this study. They were divided into two low-oxygen (hypoxia) groups – one assigned a nitrate supplement and the other given a placebo – and one normal oxygen (normoxia) group, which was given a placebo. The supplement was administered three hours before SIT sessions that took the form of short, intense cycling periods three times per week. The composition of muscle fiber was monitored as well as the muscle’s buffering capacity, the ability for the muscle to neutralize the acids that are produced during intense exercise.

For clarification, the hypoxia group was in conditions that simulated low-oxygen environments like those faced at high altitudes.

After five weeks, the researchers began to notice a change in the participants’ muscle fiber. Across all three groups, the proportion of “type IIx” muscle fibers (the “fast twitch” type) decreased. Among the hypoxia supplement group, the proportion of type IIa fibers increased, and this was not seen among the other groups. SIT seemed to improve 30-second sprint performance more in the hypoxia supplement group than in the hypoxia control, but this result was not deemed statistically significant. No effect on buffering capacity was found.

What This Means

The use of nitrate supplements alongside Sprint Interval Training increased the presence of one of the “fast twitch” muscle fiber types among those who trained in low-oxygen environments. SIT in general, seems to reduce the proportion of a separate type of fast twitch muscle fiber, and nothing seems to have impacted the muscles’ buffering capacity.

If this sounds like an extremely technical finding, that’s because it is. There’s no evidence that nitrate supplements can impact sports performance. The potential is there, but the study wasn’t designed to check for that. Also unclear is how safe long-term use of high-level nitrate supplements would actually be. Further exploration is also needed to determine whether eating more leafy greens would have any similar effects, or if supplements are the only way to get the nitrate levels required.

De Smet, S., et al., “Nitrate Intake Promotes Shift in Muscle Fiber Type Composition during Sprint Interval Training in Hypoxia,” Frontiers in Physiology, 2016;
Eckert, F., “Eating your greens could enhance sport performance,” Frontiers Blog web site, September 12, 2016;, last accessed September 13, 2016.