Glossary of Terms

Written By Tim Fleming

  • VO2max

    • A person’s maximal uptake, delivery and utilization of oxygen. Therefore, this refers to both the “central” and “peripheral” systems of the body.  Central refers to the respiratory and cardiovascular systems and peripheral refers to the muscle sites putting O2 to work for energy production.  To simplify, it’s the maximal amount of oxygen the lungs can take in, the heart to pump, the vasculature to deliver, and the muscles to take up.  For these reasons, VO2max represents the body’s capacity for energy production, health, performance and longevity. 

  • CPET (Cardiopulmonary exercise testing / VO2max Testing)

    • In short, this is a VO2max test, which is a specialized type of exercise test that measures your exercise ability. This information is obtained by the use of metabolic measuring systems that analyze breath-by-breath fractions of oxygen and carbon dioxide produced by the body’s metabolic pathways and captured at the mouth via respiration. This is a way to look at the heart, lung, vascular, and muscle systems all in one test.  

  • FATmax

    • The maximal amount of fat the body can metabolize per unit of time, commonly in grams (g) per hour, or g/hr. This is a trainable variable, either downward or upward pending performance goals.  This is also tied to units of work or speed, such as watts and pace.  This targeted area of intensity we refer to as the maximal fat-burning zone (MFZ).

  • VLamax

    • Lactate production rate, which refers to glycolytic capacity, or anaerobic capacity.  This is represented as the amount of lactate produced per unit of time, commonly mmol/min. This too, is a trainable variable, either upward or downward pending performance goals.

  • Anaerobic Threshold

    • A point where lactate production equals the rate of its combustion. Therefore, this point is tied to the capacities of the glycolytic and aerobic systems, these being the lactate production rate (VLamax) and peak oxygen consumption (VO2max).  This point is also referred to as the maximal lactate steady-state (MLSS), second ventilatory threshold (VT2), or functional threshold power (FTP). In practical terms, the highest average speed or power that can be sustained for about 1 hour. 

  • FTP (functional threshold power)

    • The highest average power one can sustain for 45 minutes to an hour. This serves as a prediction of the lactate threshold, or anaerobic threshold, and is therefore measured by field testing, such as a 20 or 60 minute all-out effort. 

  • Graded Exercise Test / Ramp test

    • This type of protocol is typically done on a rowing or bicycle ergometer, or treadmill where the load (watts) or speed is increased in consistent intervals that can range from every 30 seconds up to every 5 minutes. Some treadmill protocols also include an increase in percent grade.  At Endurance, we use this protocol primarily for respiratory gas-exchange exercise tests with the metabolic measuring system, or metabolic cart.  

  • Intermittent Test

    • This protocol is different from the traditional step test, where several bouts of exercise are performed at different intensities and durations with recovery intervals taken in between.  Endurance utilizes intermittent exercise tests for blood lactate measurements both in the lab and the field. 

  • Lactate/ blood lactate

    • A naturally occuring by-product of and a fuel for exercise.  Therefore, it serves as an intermediate between the aerobic and anaerobic metabolic pathways. The primary source of lactate is the breakdown of carbohydrate that is stored in the body as glycogen.  Lactate is produced by the muscles and transported into the bloodstream where it becomes “blood lactate.” 

  • Metabolic measurement / testing

    • Measuring aspects of the body’s metabolic pathways in response to varying levels of exertion. This type of testing can involve the use of a metabolic measuring system (refer to gas exchange, or CPET) and/or blood lactate sampling.  These are “indirect” methods of analysis that reveal valuable health and performance variables such as energy expenditure, fat and carbohydrate metabolism, and cardiopulmonary function. A typical protocol is a “step-test” format that starts very easy and ends at maximal exertion, or volitional fatigue.  Pending the type of test, these steps can range from 30 seconds to 5 minutes. 

  • Ergometer

    • A mechanical work measuring device, such as a rowing machine or stationary bike that shows and/or controls work rates, such as watts.  At Endurance, we use the SRAM, Velotron system and for cycling the Concept 2 rowing machine in our lab for exercise testing.

  • Sweat rate

    • The amount of fluid that leaves the body via sweating, often measured in litres per hour (l/hr). When measuring sweat rate by weight, such as before and after a 1-hour exercise session, it can be described in pounds or kilograms per hour then converted to l/hr. 

  • Sweat concentration

    • The amount of sodium per unit of sweat, represented in milligrams per litre, or mg/L.

  • Respiratory gas exchange

    • The difference between the ambient amount of oxygen and carbon dioxide and that released by the body through the mouth. These fractions of O2 and CO2 measured in the ventilation represent, not only the energy expenditure associated with vital function and muscle activity, but also the combustion of carbohydrate and fat as fuels for the body’s metabolic pathways and is therefore a useful way to measure metabolism both at rest and during exercise. 

  • Lactate Test

    • A test that measures the peak lactate values after a time or distance to assess the blood lactate concentration associated with each workload.  At Endurance, these are done as intermittent protocols, rather than the traditional “step test” format. Very small blood samples are taken from a small prick to the ear with a pediatric lancet.

  • Running Economy / Cycling Economy

    • Refers to the amount of oxygen consumed per unit of work or speed.  Economy of running is represented as the ml/min/kg per speed in meters per second (m/s).  For cycling, this is the watts produced per VO2 in liters per minute (w/L/min).  Both variables are influenced by many factors, to name a few: substrate utilization, technique, bike fit, muscle stiffness, and body size. Optimally, better economy means more power or speed at the same unit of VO2. This variable can be trained and improved. 

  • Field Testing

    • A field test, as one would guess by the name, is testing physiological metrics outside of the lab.  What’s great about a field test is that there’s no need to travel to a lab, the athlete is on their own bike, on a road versus on a trainer or ergometer. For runners, out on the road, trail, or on a track. And even for swimming tests done in a pool versus in a flume – so there are several benefits related to “event-like” replication.  However, field testing has its limitations.  For starters, we lose the controlled setting that a lab provides, and more importantly, field testing lacks the necessary metabolic measuring instruments that are used in a lab.  For these reasons, Endurance partnered with INSCYD back in 2017 so we could measure key performance variables with precision and accuracy using blood lactate data and/or GPS and power files to create evidence-based prescriptions outside of the lab.  So, if you want to get customized training prescriptions in the field, or with a group, give us a call and we'll bring the lab to you!

  • INSCYD:  

    • INSCYD is a validated algorithm developed by world-class level coach and physiologist, Sebastian Weber. INSCYD allows our physiologists to obtain metrics, otherwise only allowable with more advanced instruments in our laboratory, across different sports - cycling, running, rowing & swimming. Endurance uses INSCYD analytics in the lab too for our more in-depth fitness and performance assessments. Furthermore, INSCYD gives our coaches the ability to create performance and fitness projections to help fine-tune planning for both training and competition.

  • INSCYD & The Power-Performance Decoder (PPD)

    • The PPD offers a full 360° athletic performance profile assessed outside of the lab. This PPD allows our experienced coaches to test athletes remotely: outdoor or indoor. Testing can be done as part of a regular training session, alone on the road, or on a trainer. This test requires a specific set of very high intensity efforts. For cycling, testing requires either an on-board power meter or direct-drive home trainer, and for running a late-model GPS watch. 

  • Resting Metabolic Rate (RMR) Test:

    • This is a resting sample of metabolism using our metabolic measuring system. RMR testing is the most accurate way to assess resting caloric expenditures and the results are the core of a fully tailored nutrition plan that targets weight management.  This test protocol only requires a 30 minute sampling period while at rest in the lab. 

Tim Fleming
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Aerobic & Glycolytic Power (VLamax)