In a previous post I introduced VO2 kinetics, thus framing the rationale for the somewhat counterintuitive “priming” warm-up. With that in mind, in this post I’ll address the next logical consideration: how to pace a time trial.
Just as a reminder: this discussion is written with respect to time trials of ~40 min, where it’s just the athlete against the clock. In addition to the physiology, “racing” must also take account of tactical considerations—therefore, the ideas presented below may not be applicable to those involved in head-to-head competition.
Time trials are a complex beast. As a result, any research into pacing strategies will be naturally limited in scope. That is, the optimal pacing strategies for an 800m on the track and a 10km on the road will probably differ; hence, I’ve grouped some findings from the literature according to their practical application.
Short Time Trials
For time trials of roughly 2–8 min, performed under fairly stable conditions, a fast/“all-out” start seems to be advised2,3,5,12. There are a number of reasons for this:
- Maximum efforts of < 8 min will likely be performed at an intensity equal to (if not greater than) VO2max1. The speed at which oxygen uptake (VO2) rises in response to exercise is a function of the ‘error signal’ (the difference between the current and “required” oxygen uptake)2. Going out fast, therefore, will accelerate the initial VO2 response, increasing the contribution of aerobic (or oxidative) pathways to energy demands2,4. Given that the anaerobic capacity is inherently finite6, increasing oxidative energy contribution should enhance performance, especially in events of shorter duration. A word of caution: athletes should quickly adopt a more sustainable pace following a fast start (which should last no more than a minute, ideally less) so as to avoid premature fatigue3.
- By going fast out the blocks, you minimise the time spent accelerating. All the time not spent at race pace represents a performance loss. Granted, the difference is fairly small, but this difference becomes increasingly significant in shorter events8.
- Any momentum that you carry over the finish line is effectively wasted energy24. Thus; a fast start followed by a slower finish will reduce energy “wastage”.
NB: in light of recent research, it does not appear that a fast-start strategy is able to accelerate overall VO2 kinetics following a priming warm-up. In other words, the effects of “priming” and fast-start pacing (both known to speed VO2 kinetics) do not seem to be additive18.
Longer Time Trials
Things become slightly more complicated when performance time exceeds ~8 min. Unfortunately, systematic research in this area is lacking, and the research that does exist reports conflicting results. For example:
- When the first 4 min of a 20km (cycling) TT were manipulated to produce either a fast-start (+15% of average power output) or a slow start (-15%), overall finish times were faster with a slow-start9.
- In a design similar to the one above—only with the addition of heat stress—20km TT performance was unaffected by fast- and slow-start strategies (compared to a self-paced baseline)10.
- When the first mile of a 5km (running) TT was manipulated to produce either a fast-start (+3% of average pace) or a faster-start (+6%), performance on the whole was better with a faster-start11.
The general consensus among many athletes is that an “even”/constant pacing strategy is advisable for longer events. Indeed, there is research to support this assertion, especially when external conditions are relatively stable8,19,20,22. However, one cannot overlook the pacing strategy that seems to pervade virtually all world records of this duration; that is, the parabolic pacing strategy. This involves both a fast-start and a fast-finish, with a relatively slow midsection8. Such a strategy is associated with virtually all the track 5km and 10km world record performances dating back to 192112, and is consistently observed in other sports as well13,17. This pacing behaviour is similarly observed in sub-elite athletes, and to a greater extent in those who are more experienced/competitive14.
What is the Rationale Behind “Parabolic” Pacing?
- It has been suggested that our innate predisposition to go out fast is an evolved tendency2. This seems plausible, as we would not of had the luxury of measuring our efforts when trying to evade predators/catch prey.
- If we assume there exists a maximum sustainable power/pace (= critical power or CP), and a very finite capacity to work above that “threshold” (termed W′), then optimum performance cannot be achieved if power/pace drops below this CP at any point15 (i.e. you cannot ‘make up for lost time’). Therefore, one of the main strengths of parabolic pacing may be that it ensures athletes a) do not drop below CP and b) deplete the entirety of their W′.
However, not all athletes enjoy the stable external conditions of track runners, swimmers etc. For road cyclists particularly, and runners to some extent, time trials often involve tackling variable course conditions (i.e. wind & hills), so pacing should take account of this.
I’m sure this is a question many athletes have thought over at some point:
When tackling a course that is hilly and/or windy do you…
a) Try and maintain a constant effort/power—which would result in greater pace/speed fluctuations.
b) Try and maintain a constant pace/speed—which would then produce a more variable effort/power profile.
Based on mathematical modelling, the latter option seems to be advised20,21,23. That is, performance should be enhanced by efforts to maintain a constant speed, for cyclists at least.
NB: The resultant changes in effort/power may only be tolerable in the range of about ±5%22. For example, increasing power by 5% into a headwind (relative to the average), then decreasing it by 5% with a tailwind.
I’ve described some general principles for pacing according to event duration but, as with all things, there is rarely ever a ‘one size fits all’ answer. The best advice will always be to experiment with different strategies in training. Just as with any scientific study: control for as many confounding variables as you can, collect data, analyse, and repeat.
- Billat V, Petot H, Karp JR, Sarre G, Morton RH, Mille-Hamard L. The sustainability of VO2max: effect of decreasing the workload. Eur J. Appl. Physiol. 113: 385–394, 2013.
- Jones AM, Wilkerson DP, Vanhatalo A, Burnley M. Influence of pacing strategy on O2 uptake and exercise tolerance. Scand. J. Med. Sci. Sports 18: 615–626, 2008.
- Aisbett B, Lerossignol P, Mcconell GK, Abbiss CR, Snow R. Influence of all-out and fast start on 5-min cycling time trial performance. Med. Sci. Sports Exerc. 41: 1965–1971, 2009.
- Bailey SJ, Vanhatalo A, Dimenna FJ, Wilkerson DP, Jones AM. Fast-start strategy improves VO2 kinetics and high-intensity exercise performance. Med. Sci. Sports Exerc. 43: 457–467, 2011.
- Bishop D, Bonetti D, Dawson B. The influence of pacing strategy on VO2 and supramaximal kayak performance. Med. Sci. Sports Exerc. 34: 1041–1047, 2002.
- Burnley M, Jones AM. Oxygen uptake kinetics as a determinant of sports performance. European Journal of Sport Science 7: 63–79, 2007.
- De Koning JJ, Bobbert MF, Foster C. Determination of optimal pacing strategy in track cycling with an energy flow model. Journal of Science and Medicine in Sport 2: 266–277, 1999.
- Abbiss CR, Laursen PB. Describing and understanding pacing strategies during athletic competition. Sports Med. 38: 239–252, 2008.
- Mattern CO, Kenefick R, Kertzer R, Quinn T. Impact of starting strategy on cycling performance. International Journal of Sports Medicine 22: 350–355, 2001.
- Abbiss C, Peiffer J, Wall B, Martin D Laursen P. Influence of starting strategy on cycling time trial performance in the heat. International Journal of Sports Medicine 30: 188–93, 2009.
- Gosztyla AE, Edwards DG, Quinn TJ, Kenefick R. The impact of different pacing strategies on five-kilometer running time trial performance. J. Strength Cond. Res. 20: 882–886, 2006.
- Tucker R, Lambert MI, Noakes TD. An analysis of pacing strategies during men’s world-record performances in track athletics. Int. J. Sports Physiol. Perform. 1:233–45, 2006.
- Garland SW. An analysis of the pacing strategy adopted by elite competitors in 2000 m rowing. British Journal of Sports Medicine 39: 39–42, 2005.
- Lima-Silva AE, Bertuzzi RC, Pires FO, Barros RV, Gagliardi, JF, Hammond J, Kiss MA, Bishop DJ. Effect of performance level on pacing strategy during a 10-km running race. Eur J. Appl. Physiol. 108: 1045–1053, 2010.
- Fukuba Y, Whipp BJ. A metabolic limit on the ability to make up for lost time in endurance events. J. Appl. Phsyiol. 87: 853–861, 1999.
- Jones, AM, Vanhatalo A, Burnley M, Morton RH, Poole DC. Critical power: implications for determination of VO2max and exercise tolerance. Med. Sci Sports Exerc. 42: 1876–1890, 2010.
- Swimswam.Com. 2012-last update, Sun Yang’s Olympic 1500 Splits & World Record Progression. Available: http://swimswam.com/sun-yangs-olympic-1500-splits-world-record-progression/.
- Carita RAC, Greco CC, Denadai BS. The Positive Effects of Priming Exercise on Oxygen Uptake Kinetics and High-Intensity Exercise Performance Are Not Magnified by a Fast-Start Pacing Strategy in Trained Cyclists. PloS one 9: e95202, 2014.
- Padilla S, Mujika I, Angulo F, Goiriena JJ. Scientific approach to the 1-h cycling world record: a case study. J. Appl. Physiol. 89: 1522–1527, 2000.
- Swain DP. A model for optimizing cycling performance by varying power on hills and in wind. Med. Sci Sports Exerc. 29: 1104–1108, 1997.
- Atkinson G, Brunskill A. Pacing strategies during a cycling time trial with simulated headwinds and tailwinds. Ergonomics 43: 1449–1460, 2000.
- Atkinson G, Peacock O, Gibson ASC, Tucker R. Distribution of power output during cycling. Sports Med. 37: 647–667, 2007.
- Atkinson G, Peacock O, Passfield L. Variable versus constant power strategies during cycling time-trials: prediction of time savings using an up-to-date mathematical model. Journal of Sports Sciences 25: 1001–1009, 2007.
- Foster C, Schrager M, Snyder AC, Thompson NN. Pacing strategy and athletic performance. Sports Med. 17: 77–85, 1994.