Chlorella Supplementation Reduces Blood Lactate Concentration and Increases O₂ Pulse during Submaximal and Maximal Cycling in Young Healthy Adults

Chlorella supplementation is reported to improve <(V)over dot>O-2max following extended supplementation periods (similar to 3 weeks). However, there is little research on its impact over submaximal exercise intensities and following shorter supplementation regimens. This study aimed to investigate the efficacy of 6 g/day 2-day chlorella supplementation on exercise performance in healthy young adults. Twenty young healthy adults (Males = 16, Females = 4) (Age 22 +/- 6 years, <(V)over dot>O-2max 42.7 +/- 9.6 mL/(kg.min)) were recruited for this double-blinded, randomised cross-over study. Participants ingested 6 g/day of chlorella or a placebo for 2 days, with a one-week washout period between trials. Exercise testing consisted of a 20 min submaximal cycle at 40% of their work rate max (WRmax) (watts), followed by an incremental <(V)over dot>O-2max test. Lactate (mmol/L), heart rate (b/min), oxygen consumption (mL/(kg.min)), O-2 pulse (mL/beat), respiratory exchange ratio (RER), and WRmax were compared across conditions. Following chlorella supplementation, blood lactate levels were significantly lower (p < 0.05) during submaximal exercise (3.05 +/- 0.92 mmol/L vs. 2.67 +/- 0.79 mmol/L) and following <(V)over dot>O-2max tests (12.79 +/- 2.61 mmol/L vs. 11.56 +/- 3.43 mmol/L). The O-2 pulse was significantly higher (p < 0.05) following chlorella supplementation during submaximal (12.6 +/- 3.5 mL/beat vs. 13.1 +/- 3.5 mL/beat) and maximal exercise intensity (16.7 +/- 4.6 mL/beat vs. 17.2 +/- 4.5 mL/beat). No differences existed between conditions for oxygen consumption, RER, <(V)over dot>O-2max, or WRmax. A total of 2 days of 6 g/day chlorella supplementation appears to lower the blood lactate response and increase O-2 pulse during both submaximal and maximal intensity exercise but did not lead to any improvements in <(V)over dot>O-2max.