Cranberries have the highest polyphenol and antioxidant capacity among fruits and vegetables and may protect against exercise-induced free radical production, consequently improving performance. In a new study, scientists investigated the effect of polyphenol-rich cranberry extract on time-trial performance and lactate response following exercise.
Cranberry supplementation for 28 days appeared to improve running speed as well as aerobic performance in trained runners. Image credit: Michael Reichelt.
Polyphenols, including proanthocyanidins, anthocyanins, flavonols, and flavonols, are secondary plant compounds found in fruits and vegetables.
Cranberries have the highest total polyphenol content among the most consumed fruits in the American diet, and one of the highest antioxidant capacities among fruits and vegetables.
Furthermore, their polyphenol content stands out because of the high concentration in rare A-type proanthocyanidin, which is believed to be the main contributor to their beneficial effects.
The use of dietary supplements is growing among athletes, and many are turning to natural health products to improve exercise performance.
Strenuous exercise significantly increases reactive oxygen species production owing to high oxidative metabolic demands.
Consequently, polyphenols may offer natural antioxidant defense against exercise-induced free radical production.
“When it comes to elite athletes, any advantage can make the difference between finishing fifth or on the podium,” said study’s senior author Dr. Andreas Bergdahl, a researcher at Concordia University.
Fot the study, Dr. Bergdahl and his colleagues recruited 14 high-level runners who are performing at least five hours of endurance training a week.
The athletes ran two time trials over three separate visits, one a 1,500-m, the other a 400-m.
The first visit was used as a baseline. At the second, they were given a single large dose of cranberry extract two hours before running.
The athletes were then instructed to consume a small dose of cranberry extract daily for 28 days, after which they repeated the runs for a third time.
“We selected these distances to test the effects the cranberry extract had on different energy systems,” said study’s first author Francis Parenteau, a Ph.D. candidate at Concordia University.
“The 400-m is shorter and of higher intensity and involves the anaerobic system. The 1,500-m uses the aerobic system but is shorter than what the athletes usually run.”
“Since they do not train to run that distance, we were able to isolate training effects as a variable.”
Besides their running time, the researchers measured their post-exercise blood lactate, a marker for potential muscle fatigue and lack of oxygen.
They also attached a portable near-infrared spectroscopy device to the runners to measure muscle oxygenation levels before, during and after their runs.
Following data analysis, the scientists found that 28 days of cranberry extract consumption demonstrated a trend toward increased speed in the 1,500-m time trial but not in the 400-m.
However, they did notice that lactate buildup was reduced following the 400-m but not the 1,500-m compared to baseline.
The data also indicated that the cranberry extract promoted better oxygen extraction by the muscle, improved lactate clearance and slower muscle deoxygenation.
“The beauty of this is that it is all natural,” Dr. Bergdahl said.
“It is an ergogenic aid, meaning that it is performance-enhancing, but it is not an anabolic steroid.”
“Athletes can get this important boost in their performance just by consuming more cranberries.”
The study was published in the journal Physical Activity and Nutrition.
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Francis Parenteau et al. 2023. Cranberry supplementation improves physiological markers of performance in trained runners. Physical Activity and Nutrition 27 (4): 8-14; doi: 10.20463/pan.2023.0032
