Exercise Testing Options

At Endurance, we offer two options for exercise testing where each employs a unique protocol and a different set of instruments to suit a wide range of athlete abilities, experience, and end goals. These options are respiratory gas exchange (Gx) and blood lactate testing. The most common “user friendly” protocol for all levels of fitness, is a respiratory gas exchange (Gx) test, which collects ventilatory measurements used to assess fitness and create evidence-based exercise/training prescriptions. We call this the Fitness Assessment, which consists of a series of step tests to measure the full metabolic spectrum using a clinical and research grade metabolic cart, or oxygen and carbon dioxide analyzer.

Analysis is obtained by breathing through a two-way valve with a mouthpiece and nose clip while exercising at various intensities. This protocol is often referred to as a “VO2 test,” since it measures rates of oxygen consumption.

To dive a bit deeper, this protocol identifies two clearly defined physiological events, or inflection points in the rate of oxygen uptake and carbon dioxide expulsion. Identifying these inflection points is a practical way to establish training zones and assess strengths & weaknesses in one's fitness. Furthermore, Gx testing protocols provide in-depth analysis of fuel utilization to assess nutrition related variables, such as the rates of carbohydrate and fat utilization, or “FATmax.”

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From a broader perspective, Gx measurement and blood lactate sampling are used to examine the body's metabolic response to exercise. Both methods look at what's happening in the muscle cells indirectly. Gx testing measures cellular changes occurring during exercise via the lungs by sampling breath -by- breath concentrations of oxygen and carbon dioxide at the mouth. Blood lactate testing measures the appearance of lactate in the blood, where working muscles during exercise produce and consume this lactate.

Blood lactate concentrations increase at higher metabolic demand as the rate of lactate production exceeds the body's capacity to clear it. By examining the distinct inflection points along a curve of either oxygen uptake or blood lactate concentration per unit of work (watts) or speed (pace) specific training recommendations and training zones can be prescribed. Therefore, both methods are valid for examining level of conditioning and for making exercise/training prescriptions. 

However, a standard blood lactate step-test does not provide the same level of depth as gas exchange (Gx) step-test measurements. The resulting blood lactate curve does not provide data related to cycling and running economy, fuel utilization (carbohydrate & fat), or VO2max, whereas Gx testing provides all the above.

This brings us to second testing option we offer, which is the Performance Assessment. By partnering with INSCYD since 2017, we apply advanced algorithms to extract more insight from blood lactate results with, or without, the need for Gx testing. This protocol also gives us an additional variable for creating a metabolic profile, the lactate production rate (Vlamax).

Further benefits of not requiring VO2 analysis start with the option for more valid field testing, so we can test outside of the lab for running, cycling, and/or swimming. Additionally, the athlete does not have to exercise with the mouthpiece and nose clip which makes for a more comfortable testing scenario. However, this protocol does require a series of high intensity efforts that is not suitable for everyone. In the lab we also have the option to combine blood lactate sampling with Gx measurements when warranted.

For blood lactate testing in the field our diagnostics allow us to capture variables such as maximal fat burning, maximal lactate production (VLamax) and anaerobic threshold without the need for Gx.

LEARN MORE ABOUT HOW AND WHY WE USE INSCYD

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Poole, D.C., et al. The Anaerobic Threshold: 50+ years of controversy. J. Physiol. (2021) 599 (3): 737-767

Faude, Kindermann & Meyer. Lactate Threshold Concepts: How Valid Are They? Sports Med. (2009); 39 (6): 469-490.

Jones & Carter. The Effects of Endurance Training On Parameters Of Aerobic Fitness. Sports Med. (2000); 29(6): 373-386.

Olbrecht, J., et al. "The importance of a calculation scheme to support the interpretation of lactate tests." D Maclaren, T

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