Chlorella-Induced Increase in Cardiac Function Further Enhances Aerobic Capacity Through High-Intensity Intermittent...

Chronic chlorella intake combined with high-intensity intermittent training (HIIT) has been shown to accelerate aerobic and anaerobic capacities in rodents. This study aimed to clarify the effects of combining chlorella intake with short-term HIIT on exercise performance in humans, and to investigate the impact of chlorella intake on cardiac adaptation.

In Study 1, twelve healthy young men completed a 3-week exhaustive HIIT, comprising 6-7 bouts of 20 s of cycling on a leg ergometer at an intensity of 170% maximal oxygen uptake (V˙O_2max), with a 10 s rest between each bout, 3 days/week. They were orally administered either placebo or chlorella during the 3 weeks in a double-blinded, randomized crossover trial (RCT). In Study 2, six healthy young men were orally administered either placebo or chlorella during 4 weeks in a double-blinded, placebo-controlled RCT. We measured V˙O_2max and cardiac function (stroke volume [SV], heart rate [HR], and cardiac output [CO]) during maximal exercise. In Study 3, chlorella-induced changes in molecular markers of maladaptation of the heart were measured in healthy rats.

[Study 1] After each HIIT, V˙O_2max significantly increased in the placebo and chlorella groups (p < 0.05). Changes in V˙O_2max were significantly higher in the chlorella group than in the placebo group (p < 0.05). [Study 2] Changes in SV and CO during maximal exercise were significantly higher in the chlorella group than in the placebo group (p < 0.05 each), but HR_max did not change. [Study 3] Chronic chlorella intake did not change the molecular markers of pathological cardiac hypertrophy.

Chronic chlorella intake, which improves aerobic capacity by enhancing cardiac function without causing cardiac maladaptation, combined with short-term HIIT, further enhanced aerobic capacity. Thus, the chlorella-induced increase in cardiac function may further enhance aerobic capacity through HIIT.