Effects of a glucosinolate-rich beverage on blood lactate concentrations during submaximal exercise.

Ingestion of 37.5 g of glucosinolate-rich red kale sprouts (GRS) acutely reduced blood lactate during submaximal cycling compared to placebo.

• Blood lactate concentrations were 0.4 ± 0.6 mM lower at the highest work rate (~140 W) compared to placebo (p = 0.00175).
• The largest lactate reduction across doses occurred at the 37.5 g dose.
• No significant lactate reduction was observed at the lowest work rate (~100 W).
• Measurements were taken 3 hours after ingestion of GRS or placebo.

Ingestion of 75 g of GRS also acutely reduced blood lactate during submaximal cycling compared to placebo, though the effect was smaller than the 37.5 g dose.

• Blood lactate concentrations were 0.3 ± 0.5 mM lower at the highest work rate (~140 W) compared to placebo (p = 0.0484).
• No significant effects appeared at the lowest work rate (~100 W).
• The effect at the 75 g dose was statistically significant but smaller in magnitude than the 37.5 g dose.

Both doses of GRS significantly increased resting blood glucose concentrations compared to placebo.

• Resting blood glucose averaged 3.9 ± 0.3 mM after placebo.
• Blood glucose averaged 4.3 ± 0.4 mM after both 37.5 g and 75 g GRS (p < 0.0001 for each dose vs. placebo).
• The increase in resting blood glucose was similar between the two doses.

The study used a crossover design in which healthy participants completed three exercise sessions after consuming two doses of GRS or an isocaloric placebo.

• Sample size was n = 15 healthy participants.
• Participants consumed 37.5 g or 75 g of GRS or an isocaloric placebo blended into a beverage on three separate occasions.
• Exercise consisted of cycling on an ergometer at three submaximal work rates (~100, ~120, ~140 W).
• Exercise was performed before and 3 hours after ingestion.
• Outcomes measured included oxygen uptake, substrate-level oxidation, blood lactate, blood glucose, and ratings of perceived exertion.

Prior research with 7-day GRS combined with intense exercise training had previously shown reductions in blood lactate, attenuation of hypoglycemic events, improved performance, and reduced markers of oxidative stress.

• The current study was designed to investigate whether these effects could be observed acutely and in a dose-dependent manner.
• The acute single-dose design contrasts with the prior 7-day training intervention context.
• The background literature motivated investigation of two doses (37.5 g and 75 g) to assess dose-dependency.