Heart-rate has been used to measure exercise intensity for many years and the advent of heart-rate monitors makes it easy to get an indication of how hard you are training.
Simply put, the harder you ride, the higher your heart-rate will be. However, there is a delay between you doing a heard effort and you heart-rate rising so it’s only really suitable for aerobic efforts of 5 minutes or more. Thus, for High Intensity Interval Training workouts, there’s not much point using heart-rate as you will have completed your intervals before your heart has responded.
Your heart is part of your cardio-vascular system which is made up of your lungs, heart, veins and arteries. When you increase your intensity, your body will start using more oxygen so your heart-rate will start to rise and your breathing will become deeper and subsequently faster. It can take from 5 to 10 minutes for your cardio-vascular system to speed up to the required level. The fitter you get, the faster your cardio-vascular system will react.
Factors Affecting Heart-Rate
Your heart-rate is affected by several factors which you need to consider.
- Environmental Temperature : in higher temperatures your heart-rate will be higher for a given intensity.
- Stress : adrenaline will cause a higher heart-rate.
- Sleep : fatigue and lack of sleep can result in a higher heart-rate for some people while others will not be able to get it up.
- Digestion : After eating your hear-rate will increase but again you may not be able to sustain a heart-rate above a certain level.
- Hydration : dehydration will cause a rise in heart-rate.
- Caffeine : Caffeine will cause an increase in heart-rate.
- Fitness : As you get fitter your heart-rate will be lower for a given effort (power output) and your resting heart-rate should decrease.
- Health : an increase in your heart-rate may be an indication that you’re health is not 100%.
For turbo training, the Environmental Temperature will be your major factor to consider. The warmer the room temperature, the more blood will be circulated to the skin as your body attempts to cool down. This will mean less blood to your muscles resulting in a lower power output. Increased sweating will lead to dehydration resulting in a lower blood volume and an increase in heart-rate. Thus it’s crucial to have a good flow of air from a powerful fan as well as a bottle, or two , of water.
Heart-Rate Response at Given Efforts
Monitoring how your heart-rate responds to your power outputs must be done with a bit of caution as the same response may have contrasting reasons. This is why you should always be aware of how your sensations.
Generally, if your heart-rate responds quickly to changes in power efforts, it indicates that you’re physically fresh and on-form. However, if you’ve had time off the bike your heart-rate might rise quickly but you will probably notice that your effort may not be that high and that when you ease off your heart-rate may take longer than normal to decrease.
If your heart-rate struggle to respond to an increase in effort it’s usually a sign of fatigue. It may also be a sign that you are about to go down with a cold or flu.
Heart-Rate During Extended Rides
During long rides your heart-rate can respond in two ways.
- Cardiac Drift : During a long ride your heart-rate may gradually increase for a given effort or power output. This is a common phenomenon and often occurs during efforts at around Threshold. However, if it happens during an Endurance ride it is generally a sign of lack of form.
- Heart-rate drops progressively for a given effort : this can occur during any session. During a long ride your heart-rate may gradually drop due to you being unable to maintain a certain power output. This is often a result of your cardio system being unable to remove all the waste products of your effort possibly caused by heat and dehydration.
The Central Nervous System
The central nervous system can also cause a drop in your heart-rate.
Turbo Training, Riding Outdoors and Heart-Rate
People fall into three categories. Some people find that their heart-rates are higher riding indoors, some people have difficulty getting their heart-rate to rise. Others don’t notice any difference.
As heat dissipation is the major issue due to the lack of air flow compared to riding outdoors, it’s those of us who don’t perform well in hot environments that will notice the most difference and for whom it is even more important to have a good cooling fan.
Although it’s not perfect, heart-rate is a practical means of measuring your efforts levels and to assess your training volume. If you’re aware of the factors that influence your heart-rate and combine it with your sensations, then you will have a useful record of your training.