Episode 187-SportsLegs/Leslie Keener

A brief synopsis of the episode's main discussions and takeaways as well as extended references

Author

Jeff Sankoff
January 02, 2026

A supplement to reduce lactation buildup and prevent the burn? Sounds good if it works but does it? Running up for air is a running event series that shows how local efforts can have global impacts.

Table of Contents

SportLegs-a supplement that promises to improve VO2 max by shifting lactate metabolism. If only it worked.

SportLegs is a pre-exercise supplement marketed to reduce muscle “burn,” delay fatigue, and lessen post-exercise soreness. Its primary active ingredient is lactate, provided as calcium and magnesium lactate salts, along with vitamin D. Unlike most performance supplements, it contains no stimulants, caffeine, or classic ergogenic aids.

The theoretical rationale is that ingesting lactate before exercise raises baseline blood lactate levels, which may reduce the rate of lactate accumulation during exercise and improve acid–base balance. Modern physiology recognizes lactate as a useful fuel and signaling molecule rather than a waste product. However, mechanistic plausibility does not equal proven performance benefit.

When evaluated against peer-reviewed research, the evidence for SportLegs is weak. Controlled studies of oral lactate supplementation show that while lactate ingestion can modestly affect blood bicarbonate levels or perceived exertion, it does not reliably improve objective performance outcomes such as time to exhaustion, power output, or time-trial results. No large, independent, placebo-controlled trials demonstrate meaningful improvements in endurance, lactate threshold, or recovery attributable to lactate supplements.

Some users report subjective benefits, including reduced muscle burn or soreness, which may reflect individual variability, placebo effects, or changes in perceived exertion rather than true physiological performance enhancement. This contrasts with supplements like caffeine, creatine, beta-alanine, and dietary nitrates, which have substantially stronger and more consistent evidence.

From a safety perspective, SportLegs is generally low risk; its ingredients are commonly used mineral salts. Mild gastrointestinal discomfort is possible in some individuals.

Bottom line: SportLegs has an interesting physiological premise but lacks robust clinical evidence supporting its claims. It may modestly affect perception of effort for some users, but it should not be considered a proven ergogenic aid or a substitute for evidence-based nutrition, training, and recovery strategies.

Leslie Keener-Running Up For Air

About Leslie according to Leslie: Leslie currently serves as Program Director for the Running Up For Air Series (RUFA), a collection of endurance events created to amplify informed dialogue and empower organizations actively working on air quality solutions. Proceeds from Up For Air events are directed at carefully selected non-profit groups who demonstrate high-value influence strategies. RUFA currently has 7 races across 4 states of the United States, and looks to expand both within the U.S. and internationally in the near future. In addition, RUFA, in partnership with Patagonia, has hosted an International Day of Clean Air, which saw 252,000 people participate.

Our guest Leslie Keener is here to enlighten us about the Running Up for Air series, where runners literally climb mountains to raise awareness about air pollution. Yeah, you heard that right. It’s like a charity run but with a side of existential dread about the state of our atmosphere. Leslie shares the genesis of this unique initiative, which kicked off when Jared Campbell realized he was training for a grueling race while inhaling a cocktail of smog! We hash out how air quality operates as a litmus test for broader climate issues. Measuring air quality isn’t just a fun science project; it’s a critical indicator of our environmental health. And the irony? We’re out there racing against time and pollution, all while trying to catch our breath. We also touch on the various races across the U.S. that are part of this initiative. With races popping up in places like Denver and Montana, Leslie explains how each event partners with local organizations to tackle air quality issues head-on.

Episode takeaways:

  • Air quality issues are like the canary in the coal mine for climate change

  • Measuring air quality helps us understand climate change in our local areas, so get with it!

  • The Running Up for Air series combines endurance sports with raising awareness about air quality

  • Sport Legs supplement claims to help with lactic acid, but it’s mostly a money pit!

References used for the MMB

How SportLegs Works, What’s in SportLegs?

Product Website

Key Points:

  • SportLegs is a performance supplement that is composed of lactate compounds of calcium, magnesium, and vitamin D, with lactate making up 87% of the compound.

  • The website claims that when taken 30 minutes before exercise, SportLegs supplements raise blood lactate levels enough to fuel muscles, providing users with a competitive advantage.

  • The theory is that elevating blood lactate levels intentionally would limit the body’s natural production of lactate during exercise. 

  • The company claims that this will, in turn, reduce the conversion of lactate into lactic acid, which is responsible for causing muscle burns and fatigue. 

  • Consumers are told that they “can perform noticeably better, longer, with less painful muscle “burn” or limb “heaviness” during exercise, and less soreness the next day”

  • 1 pack of 120 supplements sells for $34.95 

  • Suggested consumption: 1 capsule/50 lbs of body weight (rounding up) prior to exercise, and re-dosing every 2 hours for sustained sports or tournaments 

  • 22 papers are cited on the webpage explaining how the product works

The Influence of Acute Oral Lactate Supplementation on Responses to Cycle Ergometer Exercise: A Randomized, Crossover Pilot Clinical Trial 

Ewell et al. 2024

Key Points:

  • This pilot study, conducted by the Department of Health and Exercise Science at Colorado State University, assessed the potential ergogenic effects of an oral lactate supplement, SportLegs, on regularly exercising adults.

  • The study found that lactate supplementation did not influence VO2peak, VO2 at ventilatory threshold, and work rate at lactate threshold relative to placebos, as shown in the figures provided in this paper.

  • According to this study, while lactate availability should directly influence lactate threshold, low-dose lactate supplementation did not influence physiological responses during incremental exercise to fatigue.

  • Other studies have also reported a negligible change in circulating lactate levels following consumption of lactate. Past studies have also reported inconsistent results on the effect of lactate on performance metrics. 

  • However, the paper notes that the recommended dosage may be too small to observe effects and the effects on elite athletes may differ from results observed on recreational exercisers.

Methods: Randomized, double-blind, placebo-controlled, crossover study. N=15 (n=9 males, n=6 females). Recreational exercisers consumed placebo or lactate supplement (19mg/kg) prior to two cycle ergometry exercises. Over 4 visits, VO2peak, VO2 at ventilatory threshold, and work rate at lactate threshold were measured during incremental exercise to fatigue. Power output during 20 min maximal sustained effort cycling time trial was measured. Minimum 48h between trials. Dosing as recommended by the manufacturer. 

Results: Oral lactate supplement did not influence VO2peak, VO2 ventilatory threshold, or work rate at lactate threshold relative to placebo. VO2peak (placebo: 44.3 ± 7.8 vs. oral lactate: 44.3 ± 7.1 mL/kg/min (mean ± SD); p = 0.87), VO2 at the ventilatory threshold (placebo: 1.63 ± 0.25 vs. oral lactate: 1.65 ± 0.23 L/min; p = 0.82), or work rate at the lactate threshold (placebo: 179 ± 69 vs. oral lactate: 179 ± 59 W; p = 0.41). Work rate during 20 min trial was slightly greater (4%) with oral lactate (204 ± 41 W) compared with placebo (197 ± 41 W; p = 0.02).

 

Effect of Magnesium Lactate Dihydrate and Calcium Lactate Monohydrate on 20-km Cycling Time Trial Performance

Willard et al. 2012

Key Points:

  • Since manufacturers of lactate supplements began claiming their potential to enhance performance through increased energy availability and decreased lactic acid production, they have become popular among athletes. 

  • The paper notes that the physiological rationale is limited, and previous studies have reported no significant effect of various lactate supplements on performance.

  • However, the combination of polylactate and carbohydrate has shown increases in pH levels, which points to a potential to enhance performance.

  • This study assessed the effect of ingesting a combination of calcium lactate monohydrate and magnesium lactate dihydrate on 20 min cycling time trial performance and showed no significant difference between placebo and lactate supplementation on performance metrics. 

  • While perceived exertion improved with supplementation, the paper notes that there is limited support for increased performance.

  • The authors claim that the only support for the enhancement of performance comes from the intracellular lactate shuttle theory, which is not widely accepted within the scientific community.

  • This study also notes that the lack of effect on performance may be due to lack of availability of exogenous lactate.

  • While this study did not measure blood lactate levels, a different study by Northern Kentucky University found no increase in blood lactate levels following SpotLegs supplementation.

Methods: Double-blind, placebo-controlled, counterbalanced study. N=9 recreational to competitive cyclists (n=7 men, n=2 women). 4 separate trials on 4 separate days with minimum 1 day recovery between bouts. One VO2max test to determine fitness and perceived exertion. Three 20km cycling time trial following 5 min warm-up. Participants consumed placebo or SportLegs lactate supplement 1h before trial. Performance measurements taken: finish time, power output, heart rate, perceived exertion.

Results: No significant differences between placebo and supplementation in measures of time (p=0.212), power (p=0.342) and heart rate (p=0.092). However, perceived exertion for placebo was significantly higher than with lactate supplementation (p=0.039).

Lactic Acid

Cleveland Clinic

Key Points:

  • Lactic acid, referred to as lactate, is produced when carbohydrates are broken down for energy in the absence of oxygen, such as during intense physical activity.

  • The liver and kidneys filter the lactic acid in the bloodstream to convert it into glucose.

  • While lactic acids are often associated with muscle aches and burns after a workout, the Cleveland Clinic notes that this is a common myth.

  • Recent studies indicate that lactic acid is flushed out of the muscle quickly enough not to damage or cause pain to cells. 

  • The soreness experienced in the days following exercise is due to microtears rather than lactic acid buildup. 

  • Lactate threshold tests help athletes understand their upper limits of endurance to allow individuals to train safely. 

  • While lactic acid is known for the painful side effects of a workout, it is a fuel source that signals to the body when it needs healing. 

Understanding what is lactic acid and it's impact on performance 

Melbourne Sports Physio

Key Points:

  • Signs of lactic acid buildup include weakness, burning sensation in muscles, cramping, and shortness of breath

  • Recent studies suggest that acidic environments in the muscles are not the cause of soreness.

  • Instead, cellular damage from during exercise, which is necessary for building muscles, causes soreness

  • Lactic acid build up can be reduced through proper hydration, adequate nutrition intake, magnesium consumption, warming up before strenuous exercise, proper rest periods, and balanced aerobic/anaerobic workouts

Effects of Oral Lactate Consumption on Metabolism and Exercise Performance

Morris Dave, 2012

Key Points:

  • Orally ingested lactate is used as energy and can increase pH by the consumption of protons in the process of lactate disposal. 

  • While lactate supplementation has been shown to temporarily increase blood pH through the disposal of lactate via oxidation and gluconeogenesis and bicarbonate levels and increase time to exhaustion in short, high-intensity bouts of exercise, no effects of lactate consumption on time to exhaustion in low- to moderate-intensity exercise have been shown.

  • This suggests the ineffectiveness of lactate as an energy supplement.

Not a subscriber to the podcast? Click here!

Support the podcast: TriDoc Podcast Patreon site

Need an endurance coach? TriDoc Coaching

Reply

or to participate.