In a recent post on the placebo effect, we delved into the idea of deception being used to boost or impair running performance.  I’d like to follow that up with the discussion of a recent review paper published in Sports Medicine by Jones et. Al. entitled “Physiological and Psychological Effects of Deception on Pacing Strategy and Performance: A Review”.  I highly recommend reading the full paper, but to offer those who do not have journal access a glimpse, I’ll try to highlight the more pertinent findings.

Pacing- A window into fatigue

More recent views on fatigue and performance in endurance sport has centered on the idea that our brain integrates both external and internal feedback to help regulate pacing.  So we take into account our fuel levels, oxygen saturation levels, by-product build up, as well as external factors such as distance remaining, previous experience, competition, and many other things.  Our pacing is then a reflection of making sure that we reach the finish line without fully depleting our bodies and pushing too far away from homeostasis.

Our body continually monitors and essentially predicts what pace we can run to the finish line without damaging ourselves and we adjust the pace accordingly.  As a quick example, if we know it is very hot outside, we will adjust our pace from the very start of the race.  We won’t wait until our core temperature gets near critical levels.  Instead, we have anticipation and our brain essentially runs a calculation based on available data.

How far we push is also a factor that plays a role and is dependent on prior experience and our psychological drive. If we have competition or the competition means more then it is likely that our body will loosen the reigns a little and lit us dig deeper into homeostasis violation. It is this thus a back and forth battle between psychological drive and our body trying to maintain homeostasis.

Briefly, I like to break it down into the following mathematical formula:

Performance= Mismatch (Expected Effort/Actual Sense of Effort)


Expected Effort= Previous Experience+ Psychological drive (importance)

Actual Secse of Effort= (Internal + External feedback)* Hazard + current Psychological Drive

Hazard= Mometary RPE * race distance remaining

The point is that performance is the result of how closely matched our expected effort and our actual effort is matched.  We have all of the prior experience and expectations that guide how we expect to feel.  And then our actual sense of effort is formed based on the internal and external feedback we are receiving during the race.  As described by De Konig and colleagues (2011), this information is then combined with “Hazard” which is basically your perceived effort combined with how much of the race you have left.  Based on these calculations, you either speed up or slow down.  While it sounds complex, think of it as if we reach halfway in the race feeling better than we expected to, we’ll speed up or keep the pace going.  If we reach that point feeling worse than we expected, then we slow down.

Hopefully you aren’t thoroughly confused by now, but the idea to grasp is that, feedback and expectations matters.  External feedback is where our competitors are, time, distance, splits, etc. and internal feedback would be oxygen levels, glycogen levels, muscle pH, breathing rate, etc.  Your body integrates all this information and plugs it into the formula and decides if we can keep going the same effort for the distance of the race or not.  If it doesn’t think we can, then it starts making us hurt, sometimes a lot.  The more pain signals, the more your body wants you to slow down because you are getting closer to violation homeostasis.

While this is but a brief and simplified overview, one of the ways in which we can learn more about both how pacing works and then also how fatigue manifests itself, is by looking at deception.  The end goal in pacing is to finish the race, but still within our limits so that we have not used our full reserves. Deception allows us to see how conscious versus subconscious integration works.  But also, allows us to get closer to our true physiological limits, as deception can eliminate the conscious psychological limitations that we put on ourselves.  So it provides insight and clues into how performance and pacing work.

Throughout the rest of this post, we will go through a quick review of deception tactics used and the impact they had thanks to the review by Jones et al.


When we look at deception we are really looking at is manipulating expectations.  If we go back to our little formula, we can manipulate expectations going into the race or perceived effort during it by manipulating the various sources of feedback (mostly external).  By using deception, we see how important the various feedback information is, or what role expectations play.  So let’s delve into some of them, again thanks largely to Jones et al. review of the subject.

Changing Expected race distance:

  • Ansley et al. (2004)- expected 30sec all out, got 36sec.  Performance decreased during the last 6 seconds compared to if they knew that the test was 36sec.
  • During “open-loop” exercise, where end point is unknown, pacing is cautious and RPE is kept at a steady state that they know they can complete.  Essentially when you don’t know how many you have to do, then you never tap into the reserve.
  • Unexpected changes in the duration, such as lengthening the duration half way through, can result in decreased performance depending how they are met.  When an unexpected change occurs, the reaction is for the body to make an immediate correction, so RPE goes up drastically, and therefore we slow down.  However, studies find that this occurs due to psychological factors.  So how we deal with this surprise determines how it affects performance.
  • Research by Billaut et al. found that manipulations in expected number of sprints altered the iEMG.
  • Jones et al. concluded that having an effort template from previous experience is more influential on pacing than having a known distance.

What all of this demonstrates is that knowledge of how far we are going to race for provides a set standard off which our body uses for comparison.  This is the reason why it is harder to go run hard until you can’t versus knowing you have 5 miles to complete.  In practical terms, the implication is that knowing the distance matters in terms of performance. This is largely why many exercise physiology tests like a VO2max test aren’t as worthwhile.  You don’t know the end point or how long you are going to be on the treadmill for.  It’s why much of this data does not translate to the real world.

However, it might be good to do some “blind distance” intervals where athletes don’t know the true distance they are running for, so that you can challenge there reliance on knowing how much is left.

Changing External Feedback:.

Manipulating splits:

  •  Somewhat surprisingly, most studies show that giving either falsely fast or slow splits has little effect on finishing times.  This is likely due to the knowledge of the total distance overriding the false information.
  • However, what was affected was the emotional response and economy.  So for example, if a person got false splits that they were ahead of pace, they had a positive emotional response and a decrease in the cost of running.
  • This demonstrates that split feedback can affect our emotional response.  This becomes important when accessing our “reserves” at the end, and might give us more “psychological drive” at the end if we have a positive emotional frame of mind.

Withholding feedback

  • In these studies, no knowledge of splits, distance, etc. are given.  They have largely been mixed results on whether it impairs performance or not.
  • One explanation is that experience matters.  In inexperienced athletes, they suffered a performance impairment with no feedback.  While if the tests were repeated, they got better at judging effort and competing closer to their maximum.

Manipulating competition:

  • In a study by Stone et al., they essentially pitted cyclists against an avatar of themselves, that they were told was their performance on the 1st test.  In actuality, the avatar was cycling at 102% of the speed of their original test.  Performance was improved.
  • What is interesting is that the size of the manipulation of speed of competitors (2-10%) effects whether it improves performance or not.  Showing that the correct framing is critical for performance.  It’s the goldi-locks syndrome.
  •  In many of these studies, performance improved based on an increase access to anaerobic energy reserves at the end.

Manipulating optic flow

  • In a fascinating study by Parry et al. they manipulated “optic flow” by speeding up or slowing down a projection of the road while participants cycled.
  • When the speed of the video was 15% slower than what they were actually cycling at, performance decreased.  Showing that visual feedback governs performance.


  • In a study  by Castle et al. manipulating the temperature shown to a group of cyclist can impair performance or change the pacing strategy.  When temperature readings were cooler than actual temperature, participants cycled as if they were in the cool temperature and had improved performance.

What these studies show is that manipulating feedback has a largely psychological and conscious effect.  We can change our emotional expectations in a positive or negative way based on where we are in a race, which in turn may improve or impair performance.  Additionally, you can see based on the manipulating competition research that we tend to place ourselves within some norm category.  So if you are a 4:05 miler, it’s not unexpected that you could run 4:03, but it would be to run 3:59.  Often time these norms hold us back and prevent us from having breakthroughs that we might be prepared to make.

What some of these subtle manipulations do is they let us delve deeper into our reserves.  We’ve all experienced this phenomena before in a race.  If we get to the last 300 of a 1,500 and we hear that 1,200m split and it is just slightly faster than what we expected and we are feeling good.  What happens?  We get excited, have a positive emotional experience, and realize that we can PR, and somehow we mount a kick that propels us to a new PR.  Other times, we come through the 1,200m significantly slower, and can’t kick anywhere near as fast, despite coming through slower.  When things are going well, we can dip slightly more into that anaerobic energy reserve.

SO What?

The takeaway is that we like staying in our comfort zone.  Our bodies like it when things go according to plan.  We are set up so that we have this exercise template of how things are going to go.  This is great if things go this way, but if they don’t, as you can see in these studies, the reaction is to slow down.

Therefore one of the practical takeaways is to provide an accurate expectation.  Have the mind prepared for how the race is going to feel.  Don’t be overly optimistic and think you will feel no pain, because once you get 40% in and it’s starting to get painful, your body will go “oh no! This isn’t supposed to happen yet, slow down!”.  We need to train for the unexpected.

As coaches and athletes, we need to refine our race template based on the best data we have, while at the same time being prepared for unexpected experiences.  We need to be prepared if the mismatch of how we feel versus how we expected to feel is there.  As well trained athletes, we are in somewhat paradoxical state of having to learn how to be really good at listening to our bodies at certain points, while having the ability to attempt to completely block out feedback at others.  It is in this refinement of these skills that we become experts at what we do.

Jones, H. S., Williams, E. L., Bridge, C. A., Marchant, D., Midgley, A. W., Micklewright, D. & McNaughton, L. R. Physiolgocial and Psychological Effects of Deception on Pacing Strategy and Performance: A Review. Sports Medicine.

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    1. Coach X on November 24, 2013 at 9:55 pm

      This blog post provides an interesting perspective on expectations, feedback, fatigue and limitations. It supports my belief that sometimes we put psychological limitations on ourselves and our abilities that hinder optimal performance and breakthroughs. I find it particularly interesting that correct framing determines whether or not performance is improved. So if an athlete is given false fast paces in a race if they are slightly fast this could likely improve performance, but giving too fast false paces may hinder performance. Clearly, each individual athlete responds to feedback in different ways, but the fact that all athletes have physiological responses to psychological cues proves the importance of proper mindset, mental preparation, and and openness to accomplishing seemingly impossible goals.

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