This study aimed to examine the effects of tart cherry (TC) or placebo (PL) supplementation on hypoxic exercise performance.
An athlete’s ability to perform endurance exercises, such as time trials under a specific distance or until exhaustion, is important. Tart cherry (TC) has been reported to enhance endurance exercise performance by increasing oxygen delivery to exercising muscles, perhaps through mechanisms involving an increase in nitric oxide (NO) bioavailability.
According to a recent meta-analysis that pooled previous literature, TC supplementation significantly improved exercise performance. Studies found that dietary TC supplementation extended exhaustion times or reduced time trials. However, other studies found contradictory results.
This discrepancy may be attributed to different study settings (e.g., the dosage of the supplements, exercise mode, or population characteristics).
As a result, TC supplementation was hypothesized to enhance exercise performance under hypoxia, reduce oxidative stress, and increase tissue oxygenation compared to placebo. By employing near-infrared spectroscopy (NIRS), we evaluated the kinetics of tissue oxygenation and deoxygenation in vastus lateralis muscles during exercise.
Tart Cherry Role in Muscle Recovery
The tart cherry juice contains a lot of antioxidants and anti-inflammatory polyphenol compounds, which reduce pain, accelerate strength recovery after exercise, and decrease blood markers for inflammation and oxidative stress. Although TC supplementation may not be optimal during the adaptation/build phase of training, these improvements occur during strength and endurance exercises.
Compared to other superfruits, tart cherries contain a high amount of phytonutrients, making them great for muscle recovery. In addition, this diversity of phytonutrients provides many pathways for exercise-related anti-inflammatory and antioxidant effects, including anthocyanins, flavonoids, flavanols, polyphenols, and others.
Results of the Study
The researchers conducted an incremental cycle exercise test to exhaustion (TTE) with 13 healthy participants under two conditions: hypoxia (13% O2) with PL and hypoxia with TC (200 mg anthocyanin daily for four days and 100 mg daily on day 5).
The researchers measured pulmonary gas exchange variables, peripheral arterial oxygen saturation (SpO2), deoxygenated haemoglobin (HHb), and tissue oxygen saturation (StO2) in the vastus lateralis muscle both at rest and during exercise.
A longer TTE was observed after TC than after PL during submaximal hypoxic exercise. In addition, a significant interaction between supplements and time was shown in urinary 8-OHdG excretion, in which increases in urinary 8-OHdG excretion one h post-exercise tended to be attenuated after TC.
Based on these findings, short-term dietary TC supplementation improves hypoxic exercise tolerance, possibly because HHb is lower and StO2 is higher in working muscles during submaximal exercise.