What markers track lactate threshold?

What markers track lactate threshold?

Lactate threshold is tracked by markers that reflect the balance between lactate appearance and clearance in the blood during incremental exercise. The primary marker is the blood lactate concentration curve, from which the first and second lactate thresholds are derived. Secondary markers include ventilatory equivalents (VE/VO₂ and VE/VCO₂), end-tidal gas tensions, and, in some research contexts, NAD⁺ metabolite levels. These markers are used to estimate the exercise intensity at which lactate begins to accumulate above baseline.

The work centres on the pathways of skeletal muscle energy metabolism, particularly glycolysis and oxidative phosphorylation, and their integration with systemic acid-base regulation.

Research Studies

Blood lactate concentration and the first and second lactate thresholds

Blood lactate concentration is the most direct marker of lactate threshold. During incremental exercise, lactate concentration remains near baseline until a first threshold, after which it rises. A second, steeper rise marks the second lactate threshold. These thresholds are used to define training zones and to assess endurance capacity. The markers are measured via capillary blood sampling and lactate analyzers.

Ventilatory equivalents and lactate threshold

Ventilatory equivalents for oxygen (VE/VO₂) and carbon dioxide (VE/VCO₂) are non-invasive markers that track lactate threshold. The first ventilatory threshold corresponds to the first lactate threshold, and the second ventilatory threshold to the second lactate threshold. These markers are derived from gas exchange analysis during exercise testing.

NAD⁺ metabolite levels and lactate threshold in older adults

A randomized, double-blind, placebo-controlled, two-arm crossover clinical trial is evaluating the effects of a patented age-reversal therapy, EGA®, compared to conventional nicotinamide mononucleotide (NMN) supplementation in healthy older adults. The primary outcome is cycle ergometry constant work rate exercise tolerance, measured as time to fatigue. Secondary outcomes include changes in peak oxygen consumption (VO₂peak), critical power, anaerobic work capacity, lactate threshold, and NAD⁺ metabolite levels [1]. This study is ongoing and results are not yet available.

Ergogenic supplements and skeletal muscle energy metabolism

A comprehensive review of the physiology and evidence base for ergogenic and medical supplements in cycling performance notes that direct enhancement is primarily achieved via modulation of skeletal muscle energy metabolism. During exercise, adenosine triphosphate (ATP) resynthesis is supported by pathways including glycolysis, which produces lactate. Supplements that influence these pathways may affect lactate threshold, but the review does not specify markers for lactate threshold itself [2].

Critical power and anaerobic work capacity as related markers

Critical power and anaerobic work capacity are parameters derived from the power-duration relationship. They are related to lactate threshold but are not direct markers. In the NMN trial, critical power and anaerobic work capacity are secondary outcomes alongside lactate threshold [1].

Peak oxygen consumption (VO₂peak) and lactate threshold

VO₂peak is a marker of maximal aerobic capacity and is often assessed alongside lactate threshold. In the NMN trial, VO₂peak is a secondary outcome [1]. However, VO₂peak does not directly track lactate threshold; it reflects the upper limit of aerobic metabolism.

Time to fatigue and lactate threshold

Time to fatigue during constant work rate exercise is a performance marker that can be influenced by lactate threshold. In the NMN trial, time to fatigue is the primary outcome [1]. This marker integrates multiple physiological factors, including lactate threshold, but is not a direct measure of it.

Summary of markers

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Sources

• [1] Nicotinamide Mononucleotide Supplementation for Exercise Tolerance Improvement in Healthy Older Adults
• [2] A comprehensive review of the physiology and evidence base to guide the use of ergogenic and medical supplements for enhanced cycling performance.