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Over the past two weeks I have outlined how to conduct a heart rate test and a functional threshold power test; but, I realized that I should have started from the beginning. What are the various training metrics that a triathlete should use?

Coaches, athletes, and endurance sport authors love to talk training metrics and terminology. Lactate threshold. VO2max. Cardiac output. Heart rate. Power. Rate of perceived effort. The list can go on and on…

Let’s look at a few key metrics that any triathlete or endurance sport athlete should understand, or at least a basic understanding.

• Heart Rate – The very basic definition of a heart rate is the number of heartbeats per unit of time. Heartbeats are created when blood flows through the heart and the values open and close creating an audible sound. The normal human heart beats at 60-100 beats per minute (bpm). This, of course, depends on various factors such as fitness, age, stress, etc. Heart rate in fitness is an important metric because it can measure an athlete’s fitness. Through regular endurance training, the heart becomes stronger and thus can pump more blood with each beat. As a result, the heart doesn’t have to work as hard, and the athlete’s heart rate at rest and during exercise will be lower. Measuring an athlete’s heart rate over time is a good way to measure improvement in an athlete’s endurance fitness. See how to conduct a heart rate test for more information on heart rate-based training.

• Cardiac Output – Cardiac output is measured as the amount of blood that the heart pumps through the body at a single minute. An increase in cardiac output is important because more blood is delivered to the important organs, such as the brain and liver. Cardiac output increases with regular endurance training. During endurance sports, cardiac output is an important metric because it means that more blood is delivered to the working skeletal muscles during a workout. As a result, more oxygen is transported to the muscle cells to produce energy and other metabolic waste by-products are removed from the working muscles more rapidly.

• VO2max – Endurance training not only improves cardiovascular fitness, but also improves lung capacity during exercise. Endurance training generally improves an athlete’s respiratory rate (breathes per minute) and tidal volume (amount of air per breath). Improvements in respiratory rate and tidal volume can contribute to an increase in maximal oxygen uptake, also known as VO2max. VO2max is defined as the highest volume of oxygen that a person’s body is capable of taking in and using during aerobic energy production. An improvement in VO2max is important for endurance athletes because it means more oxygen is available to working muscles for energy production during exercise.

• Lactate Threshold – Lactate threshold represents the point at which the athlete’s body requires a greater contribution from the glycolysis energy system (anaerobic system) and a smaller contribution from the oxidative phosphorylation energy system (aerobic system). At this point, lactate production exceeds the lactate removal rate and blood lactate levels increase. One of the primary goals of endurance training should be to increase an athlete’s lactate threshold.

• Power – Power is primarily a cycling metric. It is simply defined as the rate of doing work, where work is equal to force times distance. Power is measured via a power meter on a bike. See How to Conduct a Functional Threshold Power test for more information on power-based training.

• Rate of Perceived Effort – Rate of Perceived Effort, or RPE, is a psychophysiological scale, meaning that it calls on the mind and body to rate one’s perception of effort. The traditional scale called the Borg Scale is based on a scale of 6-20, where a score of 6 is equivalent of no exertion and a score of 20 is equivalent of maximum exertion. Many coaches and trainers, myself included, will use a scale of 1-10 for easier understanding by the athlete/client.

Above are several common exercise physiology and training metrics terminology that are often thrown around by athletes, coaches, and endurance sport authors. Of course, there are many more that we could discuss.

~ Happy Training!