Specifically Measuring Bike Training Intensity.
Coach's Note by Lance Watson
Your training is an ever-evolving process. The best-laid plans need to be constantly scrutinized and adjusted to make sure you are getting the most out of each and every day. Key training components to be considered in a properly periodized training program are volume, intensity and frequency, as well as technical skill development. These training components help you develop a program based around your physical capacities, adaptation, and personal needs, and must represent the current physical condition of the athlete. Shaping or modifying the training components gives structure and individuality to your daily workouts. This article will deal with monitoring your training intensity through the use of a powermeter on the bike – a measure of the exact power output or workload transferred from your legs to your bike.
For over 15 years powermeter usage has been common in the cycling community, particularly at the elite level of cycling. Currently you will not find many riders in the Tour de France without one. Over the past number of years, powermeters have made their way on to most bikes of well-known triathletes as well. While some are larger than a traditional cycling computer, powermeters are reasonably light and provide an incredible amount of feedback to the rider. Each brand works slightly differently. Powermeters use monitors and sensors in the bottom bracket, cranks, rear wheel hub, or chain tension to give the rider information about power output (wattage), cadence (rpm), speed (km/hr), distance (miles), heart rate (beats per minute- bpm), and a wealth of other data, all of which is downloadable to your home computer. They may come with their own computer head unit, or pair with your other devices or sport watch.
DIFFERENT MEASURES OF INTENSITY.
Training intensity is the measurement of how fast or at what effort you perform a workout. In very general terms, it is “how hard are you going?” Intensity can be measured several ways. The most basic is “perceived exertion”; that is how hard you think you are going. Scientifically, this method of measurement is fraught with error, and should only be used as a rudimentary way to assess your intensity in a workout. The second way to measure intensity is as a percentage of your best time for a specific interval. For example if your best 20 kilometer bike time trial 30:00 or 40km/hr, then you might do repeats of 5 kilometer intervals holding 95% of your best (which would be 38km/hr). This method of monitoring intensity is used most often, but it is not a 100% accurate way to measure intensity, as wind and terrain can wreak havoc on average speeds. A more reliable method of monitoring training intensity is through heart rate training. You might determine your average heart rate for a 20 kilometer bike time trial, your very best effort for the distance, is 160bpm. You can then try and increase your fitness by doing work at slightly higher or lower heart rates to improve efficiency and performance at your time trial heart rate. Heart monitors are a less expensive training tool than powermeters. Unfortunately though, your heart is a muscle, not a machine, and can be affected by stress, hormones, caffeine, heat and humidity, nutrition, rest and fatigue. Heart rate monitoring is an excellent body education but not always 100% reliable.
Along with heart rate, training intensity can be measured by power (watts) while cycling. This is possible with the use of special powermeters (such as SRM, Quark, PowerTap, Stages, Garmin Vector) for your bicycle, which provide you with a nice picture of your workouts and a measurement of your training intensity. Measuring power in training intensity helps you objectively evaluate your progress. The more accurately you can evaluate your training intensity, the better you can push to your limits for increased adaptation. You should use all available training markers to develop training programs. Poorly defined training programs that use less accurate training markers, lead to overtraining or under training.
SO WHAT DOES THIS MEAN FOR MY TRAINING?
Coaches have long known that you need to train at higher and more intense levels than you expect to race at, and at times much lower levels. The question remains, how do you know you are training at intensities greater or lower than racing? Over the years I have been working together with various sport and exercise physiology specialists on ways to incorporate the latest science into the cycling portion of my programs. Our goal was to improve the quantitative measures of training and to see how this could lead to refined training methodology and improved cycling performance, and to pin-point race wattage output. The use of power in your cycling workouts takes you into this next generation of scientific training.
For instance, you may find that you are out riding hill interval repeats, measuring time, speed and heart rate, and perceived effort. After putting in a great perceived-effort, you note your heart rate is slightly higher, but your times are slower. This commonly leaves the athlete asking questions like “am I over-trained, or fatigued, or past my annual fitness peak?” In this example, if you power measurement indicates you averaged 10 watts output higher than before (perhaps a 2-5% increase), you would take solace in the fact that you had a superior performance despite slower times. You might then attribute the slower times to variables like wind conditions, low tire pressure, wet pavement, etc. This would also explain a higher heart rate: your power output, the quantified amount of work you did, was higher than usual and the resulting heart rate corresponds appropriately.
A powermeter is particularly valuable when you cross-reference it against other measurable variables such as heart rate and cadence. Riding at a set power output, you may note that your heart rate is slight lower at a particular cadence (or gear selection) and on a certain terrain, indicating a more efficient gear choice for your personal physiology. For instance, you may find that when riding on a flat road at 200 watts at 80 rpm you heart rate is 170, and when you ride at 88 rpm (still at 200 watts, in a smaller gear) your heart rate is 167. This difference in heart rate and cardiovascular demand would dramatically affect your performance over a long distance cycling or triathlon event. The same specific indications can be made on hills, down hills, into headwinds, etc. Many newbies to powermeters are shocked at how much they “soft pedal” on the downhill, noting how much their watts drop. Downhill riding is often one of the first areas to improve with a powermeter.
Powermeters are very useful for race indication as well. If you are racing an Ironman you can create a ceiling for wattage output that you will not surpass, assuring you keep the 180 kilometer effort aerobic. This is a fairly surefire way to make sure that you pace yourself evenly through this grueling long distance event, and can help you avoid getting a little too competitive too early in the race. Best Bike Split (bestbikesplit.com) software exists to help specifically target your power throughout your goal race course. To quote their site, “Our math and physics optimization engine takes your power data, course info, and race day conditions to predict your race performance and create the perfect power plan so you can hit your best bike split ever”. This is very intriguing for an athlete seeking a sure fire way of guaranteeing their personal best performance throughout the varying terrain of a long distance race.
The applications of power output with the powermeters helps make this a very versatile tool for cycling. It helps you gather information about the demands of your training, so that you or your coach can better design your training programs. While this is a great training and racing tool for any person, it is an expensive investment. Quality powermeters start at around $800, and can get up to $5000 for research grade units. So evaluate your goals, evaluate your bank account, and decide whether a powermeter is right for you.
LifeSport head coach Lance Watson has coached a number of Ironman, Olympic and age-group Champions over the past 25 years. He enjoys coaching athletes of all levels. Contact Lance to tackle your first triathlon or to perform at a higher level. Find more tips on Twitter @LifeSportCoach