Since the introduction of the Polar heart rate monitor in the 1980's, the use of heart rate measurements has increased enormously. Today, almost every athlete uses heart rate measurements to monitor their training. Besides heart rate, (blood) lactate is now more and more used. In this blog we discuss the pros and cons of both heart rate and lactate measurements.
Heart rate versus blood lactate during increasing running test. (Figure from Midgley, A.W., McNaughton, L.R. & Jones, A.M. Training to Enhance the Physiological Determinants of Long-Distance Running Performance. Sports Med 37, 857–880 (2007).)
Heart rate data
Heart rate (how much times your heart beats every minute) gives an indication of the excercise intensity and can be used to indicate the general fitness of an athlete. The advantages of heart rate is that it is easy to use, relatively inexpensive and non invasive. When you start exercising, your heart rate increases. When you are well trained, this increase will be less than in untrained athletes. Therefore, heartrate can be used to define your fitness level. Heart rate can also be used as an alarm signal for stressors. High stress, bad sleep or illness will give an increase in resting heart rate.
Heart rate has also some disadvantages:
- Heart rate is influenced by internal and external factors like stress, emotions, time of the day, temperature, altitude,... This means that the same exercise intensity can have a different heart rate response in the same athlete. Therefore, it is difficult to interpret and should be used carefully.
- The increase in heart rate with exercise intensity is (normally) linear and cannot be used to define exercise thresholds (see figure above).
- There is a lag in the heart rate reaction. When you for example start sprinting, the effort (and power) increases very fast, but the reaction of the heart rate is much slower.
Because heart rate cannot tell us everything about what is happening with your body during exercise, other measurements like (blood) lactate are used. Blood lactate is extensively used in endurance athletes to monitor performance, especially during lab and field testing. As can be read in the previous blogs about Lactate in Sports and Lactate Thresholds, lactate can give very useful insights into sports performance and be used to define thresholds. Unfortunately, blood lactate had the disadvantage that it is invasive and cannot be used in real-time. Therefore the IDRO sensor is developed to overcome this disadvantages and use lactate measurements all the time.