By Vern LaMere, M.S. — Program Coordinator for the Human Performance Lab at NIFS
In our quest to find the best technological tool to provide beneficial physiological information regarding our training, some have suggested the heart rate monitor may be the answer. However, research has not established which is more useful for improving endurance performance: training by heart rate or training by pace or speed. If you only use heart rate to measure the intensity of your workouts, you may be missing the mark.
Understand cardiac drift
If you train by heart rate, you need to be aware of cardiac drift. Cardiac drift occurs when your heart rate rises slowly, but steadily, even when exercising at an even pace. This phenomenon is caused by a number of factors including wind, heat, humidity, race anxiety, overtraining, stress, low muscle glycogen stores and fatigued muscles. The magnitude of the drift will vary with the individual; however, cardiac drift can raise heart rates by as much as 20 beats per minute during a 30 minute constant-velocity workout. While cardiac drift is largely out of our control, staying relaxed, well-rested and properly hydrated before and during training and racing can help keep the drift to a minimum.
Limitations of training solely by heart rate
The most important factor to consider when monitoring intensity using heart rate is the potential effect cardiac drift will have on your pace or velocity. Cardiac drift could inaccurately signal you to slow down as your heart rate rises, although you are quite capable of maintaining a strong, even pace.
Leg muscles should be trained at goal pace
If training solely by heart rate, especially during race pace training sessions, your velocity may vary considerably. For example, if you run at 93% of your heart rate maximum in calm, cool conditions with a 6:30-minutes-per-mile pace, your pace may slow to 7:00 or even 7:30 minutes per mile in hot, humid and windy conditions. Why is this important? Your leg muscles need to become trained at your goal pace, not at a specific heart rate. They need to develop the necessary neuromuscular coordination for training and racing at a specific goal pace. Also keep in mind that during speed work sessions lasting less than three to five minutes, it is pointless to wear a heart rate monitor because it takes that long for the heart rate to reach a plateau.
Heart rate monitors can be useful tools
When combined with training by pace, and used properly, heart rate monitoring can be a very useful tool. Monitoring your heart rate allows you to train with a purpose when not carrying out pace or speed-specific workouts. It can be used as motivation for high-intensity VO2 max training or help keep intensity low during distance- and recovery-workouts, which helps avoid under- or overtraining. When used properly, it can elicit specific training effects such as increased aerobic capacity, lactate threshold, economy and speed.
Training by heart rate should not be used for all aspects of training. Avoid the temptation to wear a heart rate monitor during races. Race by pace and perceived exertion. Not only will glancing at your heart rate monitor be a distraction, it will cause your pace to be inconsistent, and more than likely it will cause you to slow down. Learning to train at a goal velocity should not be overlooked. If you can avoid some of the pitfalls associated with using a heart rate monitor, it can be an effective training tool.
For additional information please contact NIFS at 317.274.3432.