Dr Armstrong: Winter ills

Dr Stuart Armstrong, RoadCycling.co.nz's newest Kiwi coach, continues his series by discussing winter ills; upper respiratory tract Infections, coughs, colds etc.

"The most important fact to remember is overtraining will cause immune depletion and frequent infections"

As we are just coming into winter here in NZ, and the weather is turning decidedly to the cold side, I thought this would be a good time for an article on preventing Upper Respiratory Tract Infections (URTIs) coughs/colds etc. 

We are all aware of the increased risk we have of contracting niggling viral infections as cyclists.  The reason for this is thought to be one of the body’s defences called immunoglobulin A (IgA).

IgA is a substance produced in the body, more specifically in mucus, to help protect us against infections. It is found predominately in tears, saliva, lung secretions and nasal secretions.

The body generally produces around 3-5 grams of this a day. Not much, but you certainly notice a difference without it. It works by stopping adhesion and replication of microorganisms and can directly kill some viruses.

How exercise affects immunoglobulin A (IgA)

In response to one bout of exercise the levels drop by around 30-40%, but they do pick back up to normal on recovery. Moderate exercise will drop the levels immediately, but over the long term will lead to increased levels and a lowered risk of infections.

There have been many studies investigating the decrease in the level of IgA in elite endurance athletes. This has been mirrored to an increase in the incidence of URTIs in the same population. There is a clear “J” curve in the relationship of exercise and URTIs.¹ This indicates a lower risk with some exercise compared to sedentary individuals, but a greater risk as your exercise becomes more than “moderate”.

There have been good studies published in the British Journal of Sports Medicine showing that 12 months of moderate exercise in elderly subjects will increase their salivary IgA concentration by around 50%.² (ref below)

Unfortunately, the majority of training we do is outside the “moderate” category. Multiple prolonged episodes of exercise without adequate rest in between can lead to severe depletion and greatly increases your risk of viral infections – primarily URTIs.

Nobody is entirely sure why this particular substance is predominately affected by exercise but many people are looking into it. There are also a number of people looking into using salivary IgA levels as a marker of overtraining.

So what can be done to prevent this?

The most important fact to remember is overtraining will cause immune depletion and frequent infections. If you seem to lurch from one cold to the next during your winter training you should have a long look at your training/recovery balance and consider easing off.

A healthy balanced diet – fruit, veges etc. doesn’t do any harm in preventing immune depletion and aids recovery from repeated exercise bouts.

There is also an Australian company – Probiotec – who are developing an immune boosting drug based on lactoferrin. This may increase your IgA levels – clinical trials are still being done. It could be something to look out for in the future.

Other basic things such as washing your hands, putting used tissues in the bin, covering your mouth when you cough, using alcohol based wipes to clean communal telephones, keyboards and the like, and trying to avoid contact with other infected individuals also helps.

References

1 - Nieman DC. Exercise, upper respiratory tract infection, and the immune system.Med Sci Sports Exerc1994;26:128–39. 

2 - Effects of 12 months of exercise training on salivary secretory IgA levels in elderly subjects T Akimoto, Y Kumai, T Akama, E Hayashi, H Murakami, R Soma, S Kuno, I Kono.Br J Sports Med 2003;37:76-79 doi:10.1136/bjsm.37.1.76 

Any and all information obtained on roadcycling.co.nz should not be taken as a recommendation for treatment of any particular person or patient. Should you think that you, or any other individual, might require treatment for one of the conditions described here, please seek the advice of a qualified physician or doctor. Please be advised that using the information provided here in no way means that a doctor-patient relationship has been established between you and the author of the information provided on this website.

April, 2010

Other articles by Dr Armstrong

• Salt and the athlete

About Dr Stuart Armstrong.......
Dr Armstrong qualified from Glasgow Medical School in 2002. He moved to NZ in 2003 and has spent the last 7 years working as an Acute Medical Registrar in numerous hospitals around NZ. He has recently passed his Sports Medicine Fellowship exams.

Dr Armstrong is an avid triathlete. He has completed 5 Ironman distance races to date, as well as representing NZ at the World Long Course Championships in 2009.

He is also the founder and owner of Elite Race Rentals which rents the latest Zipp race wheels and Powertap training wheels. Be prepared to rip up the road like the pros. Just think of those minutes melting off your bike time.

You can find out more at www.eliteracerentals.co.nz or email him at:  This e-mail address is being protected from spambots. You need JavaScript enabled to view it