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Busting Myths on Running - 'Safe' Edition

trail runners mid-race, one with poles, other without

The internet of running is full of wisdom and great stories. As more and more elite athletes take to social media and give us all a means to celebrate the sport of running, we also find ourselves so frequently bombarded with unsubstantiated ‘free advice’ that is being circulated and blindly taken as sport science.

In this post, we’ll take a look at three such common running myths, their origin stories, and our take on why these are nothing but folklore and bro-science.

Maximum Heart Rate Should Be 220 Minus Your Age

One of the foremost research in training and exercise science was done by Fox et. al in 1971 in their paper titled “Physical activity and the prevention of coronary heart disease”. As the title suggests, the research aimed at understanding how physical activity can be beneficial to patients of CAD. However, one of the byproducts of the research became the gospel of a wide sea of students of the internet - that based on one’s age, their maximum heart rate during physical activity can be estimated.

This estimate, also called the Age-Predicted Maximum Heart Rate (APMHR), soon became the go-to for quick pills of echo-chamber knowledge, and gave rise to various spreadsheets and ‘advice’ on how one should train.

According to the paper, APMHR = 220 - age.

female runner with arms on waist, possibly tired after workout, looking from top of a hill
Catching a Breath or Catching the View?

There has been a lot of subsequent research and derivatives of APMHR have been floating around freely. Some use a (180 - age) equation, while some give ‘allowances’ to add or subtract 5bpm based on various environmental, historical or lifestyle factors. But the premise is the same - that age is the only predictor of what one’s maximum heart rate should be.

The biggest - and only - problem with this formula is that it establishes that everyone of a certain age will have the same maximum heart rate.

Here’s why we love busting this running myth:

  1. Maximum heart rate (or HRmax) is the highest level of the heart’s pumping frequency that can be achieved in an intense bout of exercise. While HRmax can not be sustained for more than a minute or two (maybe 30 seconds or so more for elites), it’s a capability metric and never an actual number. The fitter an athlete is, or the more intense an exercise bout is, this number can go up beyond 200bpm. APMHR, on the other hand, is a finite number that puts a cap, and effectively says that one’s heart rate can never go beyond 220bpm - that too for someone who is 0 years old.

  2. The equation puts everyone in the same bracket and does not take into account anyone’s training history, exercise session structure, environmental dynamics, medical history or any of the countless variables that determine cardiovascular health and output. It’s essentially saying that no 40 year-old should go beyond 180bpm (220 — 40 = 180) in any of their activities at any intensity.

  3. Heart rate itself is an outcome of increased blood demands from active muscles. This, conversely, means that the more the muscles that are active, the more the demands shall be. This essentially means that a ‘maximum’ heart rate is not really a function of intensity, but a function of musculature. And it has certainly got nothing to do with age.

APMHR, for all its shortcomings, does have merit though. If anything, beyond laying the groundwork for research on the subject, it gives guidelines for how to keep a check on intensity levels, especially for someone with CAD or someone who is new to exercise.

For athletes, though, it’s a myth that needs to be busted.

Running Cadence Should Be 180spm

Cadence is the number of steps one takes per minute (steps per minute - spm) while moving. With running, this is one of the two determinants of one’s pace/speed, the other being stride length, which is nothing but the distance or ground one covers between alternating steps of the running gait cycle (technically, half the gait cycle).

The running circles believe that for optimal ‘fast’ performance, everyone should run at a cadence of 180spm, or nearabout.

The origin of this ‘law’ can be traced back to 1984 when renowned exercise physiologist, author and coach Jack Daniels (not the one from Tennessee) studied elite marathoners’ kinetics at the Los Angeles Olympics. In his study, he found that all but one runners had a cadence of over 180spm. This resulted in the folklore that in order to run ‘fast’, one should run at 180spm.

runner, possibly male, mid stride with blue shoes
Stride Length x Cadence = Speed

Here’s why we love busting this myth:

  1. There’s really no scientific basis for the number 180 here and this is simply a case of correlation being treated as causation. It’s almost like a preference for a nice round number over something like, say, 182spm. Moreover, taller runners naturally have a lower cadence compared to shorter runners. A more recent study of the footstrike pattern and cadence of marathon runners at the 2020 Tokyo Olympics pegged this number at 185.5spm.

  2. This is outdated data with the technology, resources and the sport ranging back to 1984. There has been significant research and application towards efficient running form and dynamics that invalidate the number 180. It was also a very limited cohort at one very specific event. While studies have shown that ‘fast’ runners always run at a cadence that’s well over 180spm, restricting the non-elites to a number such as 180 can put artificial constraints that can hamper speed and running economy.

  3. What about us trail runners? We can also be fast. But we don’t do 180spm. There is absolutely no relevance of this number 180 to trail running, or any form of running other than road marathons or track events.

However, to give credit where it’s due, taking the number out of the equation immediately starts making a lot more sense. To rephrase, in order to run fast, one should have a high cadence. Whether it’s 180 or 170 or 200 is based on the individual, with the general thumb rule that the higher, the better.

Put slightly differently, more than a myth, the 180-formula is simply a misrepresentation of Jack Daniels’ and other research on the topic.

Weekly Volumes Should Not Be Increased More Than 10%

This is another of those beliefs that have their origins in folklore rather than anything scientific. For those unfamiliar, the running circles believe that any weekly volume (or mileage, to keep it simple) increase should be within 10% of the previous week, and not more.

group of runners warming up or cooling down with on the spot exercised
Weekly training volume - how much increase is safe increase?

To bust this running myth, we’ll take three examples:

  1. Beginner runner doing 10-15km per week - if we apply the law, this means a weekly progression for such a runner will be 10km → 11km → 12.1km → 13.3km and so on. By adding nothing more than ~1km each week - which translates to not more than 7 minutes of running time per week - no favours are being done. Instead, this pattern could very well make them lose interest in running.

  2. Advanced runner doing 70km+ per week - the weekly progression now becomes 70km → 77km → 84.7km → 93.1km and so on. This is simply unsustainable as each step-up will add a significant 40-45 minutes of activity time per week, resulting in higher recovery demands. For elites doing upwards of 100km each week, these demands will get exponentially higher. Blindly following the 10% rule, in this case, is simply a recipe for injuries.

  3. Recovering or returning runner - consider a runner who was putting in 50-55km per week and had to take a break due to injury or illness or any other reason for unavailability. Forcing them to follow the 10% rule makes no sense - neither from a recovery perspective, nor from a training perspective.

Though, in the interest of fairness, any increase in volume needs to be planned with caution. Athletes and coaches pay special attention to this and depending on where one is in their training phase, cutback or down weeks are planned to allow for recovery demands. For beginner runners, on the other hand, a gradual-yet-relevant increase is advised.

To sum it up, there’s no basis for this 10% number and is, again, a myth that has blindly turned into belief.


Consequences and Application to Trail Running

This is the important and the serious bit. Trail running, as a sport, is just making it to the big stages and there’s fresh interest from all types of runners to ‘try out’ trail running. However, research on trail runners is extremely limited, to the point of non-existence. In such a scenario, it is only natural for new entrants to the sport to look for advice outside the trail running circles. This, in turn, makes it very easy to fall prey to myths such as the ones shared here.

two trail runners and three mountain bikers cyclists having fun at the trailhead
Trail Runners Share Values and the Fun - Not Myths

While we’ll do another round of myth-busting with some more controversial topics in a different post, it’s important that new trail runners start where it matters the most, that is, by first understanding the values of the sport. The trails are a beautiful place and trail running is more a community than a sport. We have our belief systems and we are very protective of those. If anyone does want to learn more about the technical, performance and training aspects of trail running, the first thing they need to do is to hit the trails and enjoy themselves without taking numbers such as 220, 180 and 10% seriously. And for that, we’re just a message away.


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