Whether it’s racing or to monitor training, most athletes will be familiar with time trialling. Although ‘time trialling’ has strong cycling connotations, these posts are not just directed at the testers. Discussed below is a simple strategy that can enhance your performance when it’s just you against the clock.
This strategy is based (largely) on enhancing VO2 kinetics. Put simply, VO2 kinetics describe the oxygen uptake response at the onset of exercise15. Rather than describe this phenomenon in theoretical terms, I’ll put it in to a context that most will be able to identify with.
You’re on the start line for a TT (which will last around 20 mins, give or take) and the clock starts. More than likely you go off all guns blazing. For the first few minutes, even though you’re pushing quite hard, it feels surprisingly comfortable and you’re breathing fairly lightly (1). However, as you get further in, you start breathing heavier. At this point you try to settle into a ‘rhythm’ and find the highest rate you can hold. Even though your pace doesn’t necessarily change, as time goes on your breathing gradually increases along with your perceived effort (2). If the TT is of sufficient duration, this eventually stabilises (3). As you then approach the finish, you start to up the ante, and your breathing rate gradually rises. If you’ve played it right, you’ll hit the finish line at VO2max (4), feeling like you’ve given it everything you could.
It’s not entirely valid, but if we take “breathing” to represent oxygen uptake (VO2), then described above are some core features of VO2kinetics. These are depicted graphically below. (NB: large numbers correspond to the bold numbers within the TT narrative)
Adapted from references 5 and 12.
Ordinarily I would offer a brief explanation as to the mechanisms behind such phenomena, however, to do so in this case would not do the topic justice (interested readers are directed to references 5, 11,12). Suffice to say that any intervention that ameliorates the red-shaded areas above could potentially improve performance12.
For the present purposes, we will concentrate on TT performances of less than 40 minutes, where the majority of the trial will be performed at critical power/MLSS. This ‘threshold’, represents the boundary between heavy exercise (where a VO2 slow component is evident, but will eventually stabilise) and severe exercise (where the slow component does not stabilise, increasing to VO2max)5.
The Priming Warm-Up
In short: the inclusion of a sustained, ‘race-pace’ (or greater) effort within an athlete’s warm-up could enhance TT performance by 1-2%.
It is not entirely understood why, but it seems that a prior bout of exercise can enhance VO2 kinetics in subsequent bouts5. The net result is an increased contribution of aerobic metabolism to energy demands, a concomitant reduction in anaerobic energy provision (which is inherently finite)11 and an overall mitigation of metabolic disturbance13. Research has shown an improved high-intensity endurance time of 15-30%3 following a priming warm-up, which would be expected to enhance TT performance (i.e. average power)** by 1-2%**16. Note that the ergogenic effects of accelerating VO2 kinetics will be more marked in events of shorter duration—and, therefore, higher intensity—but will still likely be meaningful for events of longer duration (i.e. >10 minutes).
Crucially, this performance-enhancing effect is only realised when the prior bout is of sufficiently high intensity3,6. To be specific, the priming bout should be performed in the severe intensity domain, and sustained for roughly 5 minutes3; in the context of a 20–40 minute TT, this would translate to a ~5 minute effort above ‘race pace’ . This may seem counter-intuitive, but research also highlights the importance of the recovery period between the priming bout and the performance bout. Specifically, a recovery period of at least ~10, but ideally 20 minutes, seems to be advised3. This permits almost full physiological recovery, while maintaining a slightly elevated level of metabolic acidosis, which appears necessary for the effects of the priming bout6,14. Interestingly, increased muscle temperature per se does not seem to be implicated in this phenomenon7,9,11, or indeed the enhancement of endurance performance at all8. This has led some to suggest the priming bout be termed an ‘acid-up’‘rather than a ’warm-up’10.
Jones et al. 
Athletes looking to implement this strategy are strongly advised to experiment with it in training. Specifically, athletes should try to determine the optimal duration of the priming bout, and the optimal duration of the recovery period. While the most comprehensive study on this topic to date recommends a bout of 6 minutes (above critical power), followed by 20 minutes recovery3, it is unlikely that this protocol is uniquely effective. In a study with elite middle-distance runners13, the inclusion of a 200 m ‘race-pace’ effort (roughly 30 seconds) in the standard warm-up routine, followed by a 20 minute recovery period, enhanced 800 m time by ~1.2seconds (~1%). Therefore, provided the prior exercise is of sufficiently high intensity (i.e. at or above critical power/MLSS), and recovery time is sufficient, athletes are free to determine the optimal strategy for them. One further guideline, however, is that the recovery duration should probably not exceed 45 minutes, as the priming effect seems to be reduced after this time14.
On a side note, while on the topic of VO2 kinetics, it is interesting that a faster VO2 response has been observed when cycling at lower cadences17. Therefore, it might be advisable that cyclists ride at a lower cadence for the first minute (approx.) of a time trial, in order to accelerate the VO2response.
- Chidnok, W., Fulford, J., Bailey, S.J., Dimenna, F.J., Skiba, P.F., Vanhatalo, A. and Jones, A.M. Muscle metabolic determinants of exercise tolerance following exhaustion: relationship to the “critical power”. J Appl Physiol. 115(2): 243–250, 2013.
- Pringle, J.S. and Jones, A.M. Maximal lactate steady state, critical power and EMG during cycling. European Journal of Applied Physiology 88(3): 214–226, 2002.
- Bailey, S.J., Vanhatalo, A., Wilkerson, D.P., Dimenna, F.J. and Jones, A.M. Optimizing the “priming” effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance. J Appl Physiol. 107(6): 1743–1756, 2009.
- Wakayoshi, K., Yoshida, T., Udo, M., Harada, T., Moritani, T., Mutoh, Y. and Miyashita, M., 1993. Does critical swimming velocity represent exercise intensity at maximal lactate steady state? European Journal of Applied Physiology and Occupational Physiology 66(1): 90–95, 1993.
- Burnley, M. and Jones, A.M. Oxygen uptake kinetics as a determinant of sports performance. European Journal of Sport Science 7(2): 63–79, 2007.
- Burnley, M., Doust, J.H., Carter, H. and Jones, A.M. Effects of prior exercise and recovery duration on oxygen uptake kinetics during heavy exercise in humans. Experimental Physiology 86(3): 417–425, 2001.
- Koga, S., Shiojiri, T., Kondo, N. and Barstow, T.J. Effect of increased muscle temperature on oxygen uptake kinetics during exercise. J Appl Physiol. 83(4), pp. 1333–1338.
- Bishop, D., 2003. Warm up I. Sports Med. 33(6): 439–454, 1997.
- Burnley, M., Doust, J.H. and Jones, A.M. Effects of prior warm-up regime on severe-intensity cycling performance. Med Sci Sports Exerc. 37(5): 838–845, 2005.
- Gerbino, A., Ward, S.A. and Whipp, B.J. Effects of prior exercise on pulmonary gas-exchange kinetics during high-intensity exercise in humans. J Appl Physiol. 80(1): 99–107, 1996.
- Jones, A.M., Koppo, K. and Burnley, M. Effects of prior exercise on metabolic and gas exchange responses to exercise. Sports Med. 33(13): 949–971, 2003.
- Jones, A.M., Grassi, B., Christensen, P.M., Krustrup, P., Bangsbo, J. and Poole, D.C. Slow component of VO2 kinetics: mechanistic bases and practical applications. Med Sci Sports Exerc. 43(11): 2046–2062, 2011.
- Ingham, S.A., Fudge, B.W., Pringle, J.S. and Jones, A.M. Improvement of 800-m running performance with prior high-intensity exercise. International Journal of Sports Physiology & Performanc. 8(1): 77–83, 2013.
- Burnley, M., Doust, J.H. and Jones, A.M. Time required for the restoration of normal heavy exercise VO2 kinetics following prior heavy exercise. J Appl Physiol. 101(5): 1320–1327, 2006.
- Caputo, F., Mello, M. and Denadai, B. Oxygen uptake kinetics and time to exhaustion in cycling and running: a comparison between trained and untrained subjects. Archives of Physiology and Biochemistry 111(5): 461–466, 2003.
- Hopkins, W.G., Hawley, J.A. and Burke, L.M. Design and analysis of research on sport performance enhancement. Med Sci Sports Exerc. 31(3): 472–485, 1999.
- Dimenna, F.J., Wilkerson, D.P., Burnley, M., Bailey, S.J. and Jones, A.M. Influence of extreme pedal rates on pulmonary O2 uptake kinetics during transitions to high-intensity exercise from an elevated baseline. Respiratory physiology & neurobiology 169(1): 16–23, 2009.