Risky Drafting!


It can be thick and lumpy, and like most bodily secretions it’s sticky. Its consistency varies from jelly like to thick, sticky, and clumpy, and can be dependent on hydration levels (Fahy & Dickey, 2010). Its colour may give an indication of general health (Altiner et al., 2009). At best it’s a sign of a peak performance and effort, when it’s stuck across the face of a runner who’s first across the finish line. But “snot” is nothing to fear.  In fact, it’s crucial, whether we’re sick or not – phlegm is a kind of rubbish removal. The nose is not just for smelling. It functions as a “guard dog” or “watch dog” for the lungs. It humidifies and warms air,  and the nasal hairs catch bacteria, viruses, dust and pollen so that they don’t easily follow the air into our lungs and “snot” transports it out again(Geurkink, 1983). snot-rocket-800-1Most of us consider it difficult enough just managing our own snot. But runners may need to be more concerned about others’ phlegm because during training runs and races “snot rockets” fly everywhere. During runs the nose has to work especially hard, the increased breathing rate dramatically increases the demand for moisture to provide continued humidification. The snout is forced into overdrive to provide enough dampness, and as a consequence dumps extra mucus (in sometimes a seemingly endless supply) into the nasal passages.

So you would think runners would maintain a safe distance from fellow athletes and competitors but the reality is that we all benefit from tucking in behind a front runner. Cyclists use this to great effect, a cyclist at the back of a group of eight riders cycling at 40 km/hr, consumes 39% less energy than cycling as an individual because of the drafting effect (McCole et al., 1990). But cyclists are moving much faster than runners and for that reason they experience much greater wind resistance than runners. How much energy does it cost to overcome the resistance of air at running speeds – surely not much? Well, the energy cost of overcoming air resistance on a calm day was calculated to be 7.8% of total energy for sprinting (10 m/s), 4% middle-distance (6 m/s), and 2% marathon (5 m/s) running (Davies, 1980). But bear in mind a speed of 5 m/s represents a mile time of 5.22 per mile and a marathon time of 2hours 20 minutes, well beyond the capabilities of most recreational runners. So for us mere mortals who run at much slower speeds is drafting worth the risk of being soaked in bodily secretions of others? Yes it is, particularly if it’s a windy day but the bad news is that one has to be within 40 to 100 cms of the runner in front of them (Pugh, 1971), putting them in danger of a direct hit from a “snot rocket”. The strongest runner does not always win the race, remaining tucked behind a runner and allowing him or her to break through the wind for you prevents unnecessarily exposure to the wind. A smart, conservative drafting strategy can save energy and give you the reserves that you need to kick hard or just hang on at the end of the race. Do not be afraid to “tuck in” behind a few runners during a race. Your patience will pay off at the end and direct hits are rare!

 

References

Altiner A, Wilm S, Daubener W, Bormann C, Pentzek M, Abholz HH & Scherer M. (2009). Sputum colour for diagnosis of a bacterial infection in patients with acute cough. Scand J Prim Health Care 27, 70-73.

 

Davies CT. (1980). Effects of wind assistance and resistance on the forward motion of a runner. J Appl Physiol Respir Environ Exerc Physiol 48, 702-709.

 

Fahy JV & Dickey BF. (2010). Airway mucus function and dysfunction. N Engl J Med 363, 2233-2247.

 

Geurkink N. (1983). Nasal anatomy, physiology, and function. J Allergy Clin Immunol 72, 123-128.

 

McCole SD, Claney K, Conte JC, Anderson R & Hagberg JM. (1990). Energy expenditure during bicycling. J Appl Physiol (1985) 68, 748-753.

 

Pugh LG. (1971). The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal or vertical forces. J Physiol 213, 255-276.

 

 

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