There is a vast array of training toys on the market today and it is quite easy to get engrossed in the array of colorful graphs and not actually use them to improve your performance. With this in mind let's have a look at a few examples of things you can do with a heart rate monitor and power meter to improve your time spent on your bike.
Heart rate monitors are one of the most widely used training toys but by far the most widely used in the wrong way. A big misconception in the training methodology promoted in "pulp" fitness realms is that maximum heart rate is related to performance. This is one of the greatest lies in exercise physiology, and why using percentage's of maximum heart rate for training zones is ineffective. A number of physiological parameters (including sub-maximal heart rate) change with improved fitness but maximum heart rate rarely changes. This is why using percentage of maximum heart rate zones does not improve performance. As you get fitter your heart rate zones do not change, but you do! Your body is extremely good at adapting to training – if you train at the correct intensity and using inaccurate zones with induce unpredictable training effects.
Downloadable heart rate monitors allow you to look at changes in sub-maximal heart rate, which does show improvements. A decrease in heart rate for a given power output indicates a positive training adaptation as shown in figure 1 – the second interval training session resulted in lower heart rates, and a more rapid reduction in heart rate after each interval.
Monitors that have altitude and temperature are fantastic because you can quantify vertical ascent and environmental conditions. Looking day to day or week to week, a useful way of grading the difficulty of your training time is to calculate what is called a difficulty rating which is vertical ascent (metres) divided by total kilometres completed. For example, say you completed a total of 300kms in your week and climbed a total of 2kms, then your difficulty rating is 6.6 (2000m/300kms = 6.6). Then when it is time to really work on your climbing you can use this difficulty rating to help increase your climbing kms without increasing your total training time or volume. This can also be used as a log to find out at which difficulty rating you got the most improvements in climbing performance as there will be a point when the difficulty of your week is getting too high and you gain no further improvements.
Altitude can also be used to calculate the percentage gradient of climbs (this is an automatic calculation on polar heart rate monitors by "lapping" a climb). You can then compare your training climbs to those to be competed on in a race (providing you know the profile), and simulate your competition climbs in training. Unless you have power output flat road time trials are not a good indication of training improvements because weather conditions have such a big effect of speed. As an example cold air is denser than warm air and a 10-degree drop in temperature can increase time trial time by approximately one minute over 40kms, therefore giving an inaccurate snapshot of real performance. Nonetheless hill time trials, were you are travelling at low speeds are less effected by this and can provide a good an indication of climbing performance. These can be broken down into short steep (power to weight), and long gradual (strength endurance) on road performance tests.
When it comes to training for road racing looks can be deceiving. Some would simply look at the distance and average speed and train to complete that distance at that speed. However road racing is anything but a steady state individual time trial. Instead it is a multitude of accelerations that gradually wear you down. Power meters are perfect for improving training specificity as they can tell you exactly how hard you were working at every instance in a road race which you can later replicate in training. For a given heart rate power output can vary drastically as shown in figure two where heart rate was steady but power was up and down. Plus, you can directly compare a 160km road race to a 40km time trial.
Research has shown that the most effective way to ride road time trials (>5kms) is to gradually increase the pace, allowing your body to gradually get used to the intensity. Riding to heart rate and speed is an inaccurate indication of pace or how hard you are working because speed will vary with road surface and environmental conditions. Heart rate takes time to adjust to the power output you are riding at, so it is far to easy to "over cook" those crucial first kilometres and dig a hole that takes half the time trial to get out of. Unlike these variables, power output tells you your wattage at that instance, and you can pace your time trial effectively from start to finish once you know what wattage you can achieve over the required distance. This can also be used to pace judge a breakaway in a road race.
Power meters are great tools for continual monitoring of training zones. A one-hour time trial (average power output) is a good estimation of lactate threshold and can be performed anywhere and power based training zones calculated from this information.
Both power meters and heart rate monitors calculate caloric expenditure. Heart rate monitors tend to overestimate expenditure compared to power meters however both can be used to regulate training and racing nutrition. If intake is well below expenditure in a race it is more than likely that you will be performing well below your potential.
This has only scratched the surface of the things you can do with a few of the many training toys available. Technology and cycling now walk hand in hand and while some seem quite complicated they are worth their weight in gold (and entertainment) because when combined with a good training program make improvement almost unavoidable.
Amy Taylor is an Auckland based Exercise Physiologist with a MSc(Hons) in Sports Science. One of the founders of Kinetic Edge Training Technology (www.kecycling.com) she coaches recreational to World Champion cyclists and has been cycling herself for 14 years. This article originally appeared in New Zealand Endurance Sport Magazine.