For racers, and many recreational riders, tracking ones training is a standard part of each days routine. We jump on the bike with our power meter, heart rate monitor, GPS and speedomet looking to document, and later interpret, what we’ve done. But what measures truly matter? This first of two articles looks at some of the more common methodologies and metrics.
With both the Tour of California and the Giro D’Italia capturing our attention last week it’s easy to be repeatedly impressed by the efforts and talents of the pro peloton. Rider after rider produced mind numbing efforts during both races, surely piquing the interest of aspiring racers and fans eager to baseline those efforts against their own talents and abilities.
Of course these performances are built on years and miles of consistency and diligent development of the varied physiological systems required. Chances are these riders have a keen knowledge of their training zones!
The Value of Training Zones:
Nearly all training zones are based on maximums. How much, how long and how high? Heart rate based training has long been the standard of measure most often used and cited. One reason that max heart rate is so strongly held is because of its expected relationship to VO2max and other measures of physiological strain. Since VO2max represents maximal aerobic capacity it provides a great reference point for what is happening to the athlete physiologically. Lactate blood profiles, cardiac output, and other measures track similarly.
Pick up any mainstream information source, and many educational ones to boot, and they will as likely as not reference the ubiquitous 220-Age calculation as a starting point for setting up those zones, but why is this?
A Short History:
Robergs and Landwehr, researchers out of the University of New Mexico, sought to find an answer via their 2002 article in the Journal of Exercise Physiology. Their paper did an exhaustive review of the literature seeking to find the roots of max heart rate calculations during exercise, especially 220-age, as well as best practices in applying the correct calculations and metrics. The eventually referenced the origin of the formula to Fox et al in 1971 and as they put it “...surprisingly, the origin of the formula is a superficial estimate, based on observation, of a linear best fit to a series of raw and mean data.”
The Fox article looked at research conducted on activity and heart disease. The original citation had a mere 35 data points and was not derived from original research. In fact Fox et al noted in their article that “…no single line will adequately represent the data on the apparent decline of maximal heart rate with age. The formula maximum heart rate=220–age in years defines a line not far from many of the data points.” So even the researchers in the original article that became the bedrock for decades worth of fitness musings, teachings and prescriptions didn’t feel that it was an absolute measure!
To try and parse out a ‘true’ Max Heart Rate (MHR) calculation, Robergs and Landwehr went back and attempted to replicate the research and cross reference with additional research that is often cited in relation to MHR estimation. They looked at over 30 different ways to calculate MHR, including the first known effort by Sid Robertson in 1938 (whose estimate was 212 – 0.77(age)). Their conclusion was that, indeed, even the original research cited by Fox had failed to support the 220-age calculation. Instead they built the following formula as the best overall starting point based on the research presented in the graph below (a reproduction of the Fox research):
HRmax=215.4 – 0.9147(age)
The Karvonen Version:
The prevalence of the 220-age calculation is reinforced by another commonly referenced training zone calculator – The Karvonen Formula. Karvonen is credited with the idea of Heart Rate Reserve (HRR), which is an effort to better understand the available capacity of the individual. The HRR Calculation looks like this:
(220) - (your age) = MaxHR
(MaxHR) - (resting heart rate) = HRR
(HRR) x (60% to 80%) = training range %
(training range %) + (resting heart rate) = (your target training zone)
Interestingly, Karvonen, when asked by Robergs and Landwehr, said he had never published original research of the formula and instead referred to the work of Astrand for the original calculation. Astrand, also deferred to other researchers when asked about his role by Robergs and Landwehr in September of 2000.
Whatever the derivation, the main takeaway message seems to be that using a univariate approach to estimating maximum heart rate is open to errors due to the variability within individuals, but they do provide a good starting point
Perceived Exertion:
Another common metric across time has been the estimation of effort based on the athletes perceived exertion. Perceived exertion has been shown time and again to correlate well with the actual work load in experienced athletes. The work of Gunnar Borg is the most often used baseline for rating of perceived exertion (RPE) and dates to 1970.
The original Borg scale used a range of efforts between 6 – 20 to delineate subtle differences and offer a highly refined value. Some feel that taking one’s base RPE multiplied 10 should closely correlate to exercising heart rate, offering yet another way to cross reference effort. More and more athletes and coaches are using a modified Borg scale that ranks effort from 1 – 10. This is partly to ease use and interpretation for the athlete as it requires less pre-workout education and is more intuitive for many athletes.
Summary
Training zones and intervals are as common in cycling parlance as wheels and tires. Nearly every athlete uses some metric to track their training and improvement. Yet, the most common measure used over the last three decades was not built on direct scientific research, and is prone to error. The standard 220-age calculation was derived from an interpretation of unpublished research but does provide a starting point for creating ones training zones. Similarly, the Karvonen formula is a derivation of 220-age, yet also offers a form of insight. Borg’s scale of perceived exertion has also been a long standing reference of well established validity
To be sure the science of performance has made strides over the last years, but do these measures provide a more accurate baseline for training? Next time we’ll delve into the efficacy and value of power and lactate based training zones by asking some of the sports most noted coaches and physiologists their opinion!
References
ROBERT A. ROBERGS AND ROBERTO LANDWEHR, THE SURPRISING HISTORY OF THE "HRmax=220-age" EQUATION. ISSN 1097-9751, Volume 5 Number 2 May 2002, Official Journal of The American Society of Exercise Physiologists (ASEP).
For racers, and many recreational riders, tracking ones training is a standard part of each days routine. We jump on the bike with our power meter, heart rate monitor, GPS and speedomet looking to document, and later interpret, what we’ve done. But what measures truly matter? This first of two articles looks at some of the more common methodologies and metrics.
