It is known that fruits and vegetables can bring many benefits to the body, such as reducing risks of heart disease and cancer, maintaining weight loss, boosting the immune system, and keeping skin healthy.
Many green foods are rich in nitrate. Recently, researchers find that nitrate intake can change muscle fibers and improve sport endurance and performance. The finding is newly published in Frontiers in Physiology.
The study was conducted by University of Leuven in Belgium, Victoria University in Australia, Nottingham Trent University in UK, and Université catholique de Louvain in Belgium.
In the study, researchers focused on the influence of nitrate intake on people’s performance in sprint interval training (SIT). In this training, people do 30-second sprints 4-6 times, and after each sprint they rest 4.5 min.
They trained 27 adults in 3 different ways: SIT in normoxia (oxygen tensions between 10-21%), SIT in hypoxia (oxygen tensions > 21%), and SIT in hypoxia with nitrate supplementation.
All people took part in 5 weeks of sprint interval training (SIT), and nitrate capsules were taken 3 hours before each session. Before and after SIT, participants took several muscle and sprint tests.
Researchers found that the proportion of type IIx muscle fibers decreased in all groups, but only in the nitrate group the number of type IIa muscle fibers increased. Type IIa muscle fibers are used more during sustained power activities and are more resistant to fatigue.
Furthermore, SIT + nitrate enhanced the 30-second sprint performance compared with SIT only.
Researchers suggest that SIT in hypoxia with nitrate intake can increase specific muscle fibers that are related to better performance in short sport exercise.
This finding implies that eating foods naturally rich in nitrate may benefit sport performance. Nitrate can be found naturally in fruits, vegetables and grains, because it is an essential plant nutrient found in soil.
Vegetables high in nitrates include lettuce, beets, carrots, green beans, spinach, parsley, cabbage, radishes, and celery. In fruits, strawberries have the highest nitrate content.
Citation: De Smet S, et al. (2012). Nitrate Intake Promotes Shift in Muscle Fiber Type Composition during Sprint Interval Training in Hypoxia. Frontiers in Physiology. doi: 10.3389/fphys.2016.00233
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