Should I train and race with a heart rate monitor or a power meter? What are
the pros and cons?
For mountain bike training, I
recommend using a power meter, perceived exertion and a heart rate monitor. The
more data you have, the more tools you have at your disposal to measure
performance and improve your training
Use a power meter extensively in
training to best mimic racing demands, track measured changes in fitness, nail
training objectives, and effectively calibrate perceived exertion with
reality. Changes in power output
give you a direct, objective measure of the effectiveness of your training
plan. Heart rate will let you know
you are alive.
Power (Watts) is a direct measure of
exercise intensity, whereas heart rate is an indirect measure of exercise
intensity. Heart rate is a response to exercise and other factors (heat,
humidity, altitude, diet, caffeine, stimulation, motivation, fatigue, time of
Clear vs. Crystal Ball?
Performance is accurately measured
with power. Power data is crystal clear. You either produced the watts or you
did not. Heart rate data requires guess work to interpret the result due to the
many variables included. A crystal ball may be helpful in order to draw real
conclusions from heart rate data.
vs. Time Lagged
Power has an immediate reaction to
changes in exercise intensity. Heart rate has a time lag of about 30 seconds in
its response to changes in exercise intensity. This makes heart rate a useless
pacing tool for efforts of less than 30 seconds and for the first 30 seconds of
any longer interval. Heart rate encourages athletes to over-pace at the start
of an interval in order to quickly get their heart rate into the target zone.
When training with power you can immediately peg the exact goal exercise
intensity and train with accuracy.
Hereís an example:
The goal in the following workout was to maintain a steady power of 265
Watts. The rider also wore a heart
rate strap, so we have both sets of data. (see Example 1 in photo bar above)
Not only does heart rate lag
effort by 30 seconds, it can also creep upward over time. Imagine if this rider didnít have the
benefit of the power readings, and instead attempted to drive HR up to 165bpm
in the first few minutes. The
result would likely have been an interval ending meltdown about 18 minutes in,
and at the very least a drastic reduction in power in the 2nd half of the
There are several software
applications available to crunch your power data. They will analyze, interpret
and summarize. You can look at how fast and hard you are pedaling with Quadrant
Analysis (QA) to see if you are mimicking the demands of racing in your
training. You can get a measure of the intensity of a ride (IF), the
variability of a ride (VI) and the training stress (TSS) of a ride.
Performance Manager Chart
PMC is a valuable tool for
mountain bikers. It uses ride TSS scores, averaging them over days and months.
Analyzing a single ride is like looking at a single tree in a forest. You get a
nice picture of that tree but donít know where it sits in the forest. The
beauty of the PMC is that it tallies up TSS over time to give a birdís eye view
of the forest Ė or your entire season (or even cycling career). The PMC can be
used retroactively to look at scores during times you had personal best
performances and during times you thought you should have but didnít. It can be
used for forward planning to target a specific set of scores known to put you
in peak form and to time that peak form to land smack bang on race day. The PMC
takes much of the guess work out of training, tapering and peaking.
Whether or not to race with a
power meter depends on the priority of your race. In low priority training
races, go for the power meter.
Race data often uncovers oneís strengths and weaknesses, and can also
turn up some surprising finds with regards to race demands. Race files are a powerful piece of the
As an example, using Quadrant
Analysis (a feature of WKO+ 3.0) with power meter data from single speed
mountain bike races shows a particularly high concentration of power in the
VO2max range with cadences below 60. This means pedal forces are much higher on
average than when riding with gears.
This has led to some novel training methods for single speeders.
Goal events are different. By the time you have reached a fitness
peak, all those hours of training with a power meter have worked to "calibrateĒ
your perceived exertion (PE). PE
is your best option for pacing goal events. Youíll know what you can do and for
how long, and with enough experience, PE alone will guide you to your best
drawbacks to mountain bike racing with a power meter
Power meter and heart rate
monitors are not 100% reliable. How will you pace the event if your gadget
Power meters are heavier than
race-weight wheels or cranks.
The highly variable nature of
power production in mountain bike races makes it quite difficult to turn the
real time power data into actionable information. Short accelerations and race starts are deep into anaerobic
power levels, even for longer endurance events. It is tough to make sense of the numbers without software.
Mountain bike race starts are
mayhem. The place for your eyeballs during a race start is on the trail, your
surroundings and fellow racers and not on a little monitor screen.
meters can even make you slower in a peak race!
More importantly, pacing with a
power meter may actually hold you back from a breakthrough performance! On a
top priority race day your body should be in peak condition; trained, tapered,
fueled, hydrated and ready to go. You should be poised to set records by
producing more power and going faster than ever before. Pacing yourself using
power numbers established in training may act as a governor on your peak day
and could hold you back from a potential record performance.
There is often quite a difference
between what you think you did in a race (or, what you tell your coach you did)
and what you actually did. Power data tells all! You can learn how to pace
races more accurately and how to repeat outstanding performances from the data.
Race data is useful in learning how much power you needed to win a certain race
and in what pattern that power was created. This type of information is
valuable in order to design better training plans and improve future
Without a doubt, train with a
power meter. Also, race your lower
priority events with the power meter to help objectively assess your strengths
and weaknesses, helping you dial in your training for the goal event(s). For peak priority races use your
lightweight race equipment and rely on a well calibrated sense of PE to reach
new performance heights.
Lynda Wallenfels is a USA Cycling
Cat 1 certified cycling coach and pro mountain bike racer. She is owner of LWCoaching.com.