Twenty-one days of spirulina supplementation lowers heart rate during submaximal cycling and augments power output during repeated sprints in trained cyclists

Spirulina supplementation is reported to improve time to exhaustion and V╠çO2max. However, there is limited information on its influence over the multiple intensities cyclists experience during training and competition. Fifteen trained males (Age 40 ± 8 years, V╠çO2max 51.14 ± 6.43 ml/min/kg) ingested 6g/day of spirulina or placebo for twenty-one days in a double-blinded randomized cross over design, with a fourteen-day washout period between trials. Participants completed a 1-hour submaximal endurance test at 55% external power output max and a 16.1km time trial (day 1), followed by a lactate threshold test and repeated sprint performance tests (RSPTs) (day 2). Heart rate (bpm), Respiratory Exchange Ratio, oxygen consumption (ml/min/kg), lactate and glucose (mmol/L), time (secs), power output (Watts), and hemoglobin (g/L) were compared across conditions. Following spirulina supplementation, lactate and heart rate were significantly lower (P<0.05) during submaximal endurance tests (2.05 ± 0.80mmol/L Vs 2.39 ± 0.89mmol/L & 139 ± 11bpm Vs 144 ± 12bpm), hemoglobin was significantly higher (152.6 ± 9.0 g/L) than placebo (143.2 ± 8.5 g/L), and peak and average power were significantly higher during RSPTs (968 ± 177Watts Vs 929 ± 149Watts & 770 ± 117Watts Vs 738 ± 86Watts). No differences existed between conditions for all oxygen consumption values, 16.1km time trial measures and lactate threshold tests (P>0.05). Spirulina supplementation reduces homeostatic disturbances during submaximal exercise and augments power output during RSPTs.Novelty bullets:• Spirulina supplementation lowers heart rate and blood lactate during Ôëê1-hour submaximal cycling. • Spirulina supplementation elicits significant augmentations in hemoglobin and power outputs during RSPTs.