What's Cool In Road Cycling

Toolbox: Priming the Engine

Cyclocross season is steadily progressing from the early season of warm and dry race days to the downright miserable and ugly weather that define the sport. With such nastiness, the temptation may be to skip the warmup and just hammer off the start line. Does a warmup really gain you a concrete advantage, and what type of warm-up might be best?

Racing is Racing, but I Gotta Warmup in This?
I’ve been working on a bad habit that’s progressively getting worse and worse. As the cyclocross season progresses and the hours of daylight gets less and less, I find myself leaving the house just a little bit later each weekend. With the usual prep time at the race site also progressively getting longer and longer each week due to needing just that extra layer of clothing or embrocation, the time before race start disappears rapidly. Therefore, I’ve been finding myself with less and less warm-up time each race.

As a result of the lost time at both ends, in each of the two races this past weekend, I’ve barely had time to do a single slow recon lap before racing for the start line. Indeed, I had the joy of starting pretty much DFL on Saturday because of this, although I somehow managed to slip and slide my way forward in an absolute mud bath to an eventual 4th place. I definitely paid for my procrastination Sunday though, as I thought my lungs would both collapse after a long hard ride-up hill partway through the first lap, and never felt like I had a good solid lap overall.

So as an amateur cyclist and a professional scientist, the hard question must be asked. Would my performance have been better if I had a decent warm-up, or indeed any warmup at all?

The Science of Warming Up
Physiologically, what are the potential purposes and benefits of a warm-up anyway? A number of ideas have been advanced, mainly revolving around a “priming” of the body’s metabolic and muscular machinery. Some potential mechanisms include:
• An increase in body and muscle temperature.
• Acceleration in oxygen kinetics improving oxygen availability.
• Decreases in lactate accumulation.
• Increasing heart rate and elevated cardiac output priming the cardiovascular system.

There are of course downsides to everything, and warm-up is no different. It appears that a fine balance must be made between elevating muscle temperature and oxygen uptake while not overly fatiguing the body. If warm-up is too intense (both through duration and/or intensity), it may end up being counterproductive. Glycogen stores may be unnecessarily depleted, body temperature may go too high (not usually a problem at CX events in Canada, but certainly a problem in track events and during summer racing), and other aspects of physiological homeostasis may be overly disturbed. That’s one of the reasons you saw the Garmin riders with special cooling vests on during TT warm-ups, with the dual goal of a metabolic/muscular warm-up without over-heating.

Hajoglou et al. 2005
Surprisingly, despite a popular consensus that a warm-up is beneficial, the systematic investigation of this question, and the related question of what constitutes an optimal warm-up, is relatively sparse in the scientific literature. Into this gap comes a 2005 study based out of Carl Foster’s lab at U. Wisconsin – La Crosse, with other noted cycling scientists Jos de Koning (Netherlands) and Alejandro Lucia (Spain) as collaborators.

Basics of the study:

• The exercise context and test was a 3 km TT. While this may not be truly representative of road, MTB, or cross racing, it is certainly consistent with the high intensity initial effort of many types of bike racing, which can then have a major impact on the subsequent phases of the races.

• 8 well-trained cyclists (all males) participated.

• All subjects performed an initial max testing session, along with a familiarization session.

• The 3 km TT was performed on an ergometer fitted with a SRM monitor.

• Metabolic data was recorded to calculate oxygen uptake and gross efficiency.

• Subjects had constant feedback of speed and distance completed, similar to what they might have in an actual competition.

• The only instruction provided was to complete the 3 km TT as fast as possible.

Three warm-up protocols were tested.

• No warm-up. Subjects sat on the ergometer for 6 min and then did the TT.

• Easy warm-up. 3×5 min at progressively higher but submaximal intensities (power output at 70, 80, 90% of ventilatory threshold), then 2 min rest before the TT.

• Hard warm-up. 3×5 min as above, followed by 3 min at the Respiratory Compensation Threshold, which is a bit above what we would consider as our threshold power, followed by 6 min rest before the TT.

To Warm or Not to Warm?
The main finding of this study supports the long-held consensus: warm-ups were definitely beneficial. Compared to both the easy (266.8 +/- 12.0 s) and hard (267.3 +/-10.4 s) warm-up conditions, the no warm-up trial was significantly slower (274.4 +/-12.1 s) for overall time. Most of this was attributed to higher power outputs and faster times for the two warm-up conditions during the first 1000 m. For example, power outputs averaged over the first 500 m for no, easy, and hard warm-up were 378, 421, and 431 W, respectively. In turn, the harder initial effort did not cause a problem later on in the TT, with the final 2500-3000 m split at 342, 354, and 343 w.

In summary, any kind of moderate to hard warm-up seems infinitely preferable to no warm-up at all. Therefore, set your departure time and stick to it! Also, do whatever you need to in order to trim and optimize your on-site preparation so that you’re not fiddling away precious time once you arrive.

Easy Does It or Hammer-time?
The second main question was whether there was a difference between an easy and a hard warm-up. On this topic, the data points to no significant difference in any of the measured values.

The good news here is that the type of warm-up doesn’t seem to be as critical as simply getting your body some exercise before the race itself. Don’t just simply spin an easy gear, but at least do a few tempo efforts of 3-5 min.

Physiological Benefit of Warm-Up?
The third question the study attempted to answer was the mechanism underlying the improvements observed with warm-up. From the oxygen uptake data, it appears that one main physiological function of a warm-up may be to accelerate your oxygen uptake kinetics. In simple terms, you’re priming your system by already getting blood flowing and your aerobic metabolism activated.

Oxygen uptake in the two warm-up conditions were higher in the first 1500 m compared to the no warm-up condition. This suggests a higher aerobic contribution to the total cost of exercise. However, because it was a self-paced test, it remains unclear whether the higher oxygen uptake with the two warm-up conditions was due to simply the higher power outputs rather than any physiological difference.

Regardless of the physiological mechanisms, this study’s data strongly supports the importance of properly getting ready, given the clear performance improvements with both styles of warm-up versus not having one at all. As I’ve written previously, getting the hole shot in cross can be so vital, and the lost initial time can mean a lot of work later on. Add to that the additional risk from trying to weave through slower riders while the frontrunners have open lanes in front of them, and being ready right from the start becomes an important strategy.

Remember that, especially at a cross race, you need to both recon the course AND physically get ready. This might involve riding an easy lap or two and then attacking the course to check out those same lines at race pace, so budget at least 30 min of actual riding time before the start of the race. Alternately, recon the course and have the bulk of your warm-up on the trainer.

Have fun this cross season!

Hajoglou, A., C. Forster, J.J. de Koning, A. Lucia, T.W. Kernozek, and J.P. Porcari. Effect of warm-up on cycle time trial performance. Med Sci Sports Exerc 37:1608-14, 2005.

About Stephen:
Stephen Cheung is a Canada Research Chair at Brock University, with a research specialization in the effects of thermal stress on human physiology and performance. He can be reached for comments at [email protected] .

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