Analysis: Research on elite sportspeople has found that saliva markers provide a good indicator of susceptibility to falling ill
A research study carried out with an elite rugby academy team discovered an interesting link between saliva markers and the common cold. The study found that a player's was at a high risk of contracting an upper respiratory tract infection (ie the common cold) in the following 2 weeks if their saliva immune marker (IgA) decreased by 65% or more.
Common colds are one of the most frequent illnesses reported in Ireland and amongst athletes. Upper respiratory tract infections (URTI) can lead to missed training or work days, affecting subsequent performance and can mean athletes are unable to compete in competitions. An URTI can be defined as having two or more of the following symptoms for two or more days: a runny nose, nasal congestion, headache, sore throat, sneezing, stuffy nose or nasal discharge. It can leave you feeling tired, unwell and generally low, which everyone wants to avoid.
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From RTÉ 2fm's Jennifer Zamparelli show, Nurse Sarah Kearns on the common cold
We know there are certain ways you can catch a cold. These include (i) close contact with someone who has symptoms - this is especially the case in team sports, due to the close proximity and contact between teammates, and the wider support staff, which promotes transmission of the infection; (ii) poor hygiene such as not washing hands with hot soapy water; (iii) sharing items such as water bottles (athletes do this a lot) or household towels and (iv) intense training (exercise).
A fifth symptom is reduction in immune markers, such as Immunoglobulin A (IgA). This is an antibody and immune marker found in mucosal surfaces and saliva. It's the body's first line of defence, providing a barrier to viruses and antigens, which can be responsible for causing an URTI. Salivary IgA (sIGA) binds to the antigens and neutralises the viruses by inhibiting them, therefore reducing the risk of getting an URTI. If there is a decrease in salivary IgA, there is reduced defence and increased risk of contracting an URTI. Previous research had found that intensive training, and a decrease in salivary IgA, can lead to athletes being more susceptible to developing an URTI.
We can now see that players were more susceptible to getting sick within the subsequent 2-week period if salivary IgA decreased by 65% or more. The reduced immune markers meant there was not enough to stop the virus, leading to a risk of contracting the common cold. Interestingly when players had an URTI, salivary IgA levels were no different compared to without an URTI. It was only in the two weeks before an URTI that players’ salivary IgA decreased. This means that the immune markers were building back up to fight against the virus.
In the research study, there were 15 incidences of common colds reported over the 10-week pre-season period (70 testing days) and the probability of a player contracting an URTI was 21%. Of these 15 incidences, all players had decreased IgA. However, it must be noted that some players had decreased IgA but did not contract an infection so that is why it is important to note increased risk.
Does exercise increase the risk of catching a cold?
Regular exercise of a moderate intensity has been found to reduce the risk of an URTI, but too little or prolonged intensive exercise increases the risk of contracting an URTI. Most elite athletes train at moderate to high intensity, but it has been found that a high cumulative two- and three-week training load increased the risk of soccer players contracting a URTI.
Cumulative high-intensity training or high-intensity prolonged activities, such as running a marathon, cause a suppressed immune function, which leads to an 'open window’. If athletes or the general population continue to train or compete at a very high level, without sufficient recovery, they are at an increased risk of contracting an URTI.
As a result, athletes and the general population should calculate their training load to ensure they are gradually progressing, and ensuring sufficient recovery time to reduce high cumulating training loads. Training load can be calculated by multiplying your session duration (in minutes) by how you felt (rate of perceived exertionon a scale of 1 to 10, with 10 for maximal and 1 for very easy). At the end of the week, every session RPE is added together to gain the weekly training load. For cumulative training load, each weekly training load total is then added together to calculate 2, 3 and 4-week cumulative training load.
Most elite athletes train at moderate to high intensity, but it has been found that a high cumulative two- and three-week training load increased the risk of soccer players contracting an infection
For example, if you did a running session for 60 minutes and you found this a hard session (RPE 6), the training load for that session would be 60 x 6= 360 units. You would then add up all the sessions for that week to provide the weekly training load.
While saliva testing is expensive and the likelihood of individuals being able to use saliva testing regularly is slim, it is interesting to know the window during which you might contract an infection. On the other hand, training load can be managed with sufficient recovery, ensuring training is progressed gradually based on the individual’s training history, goals, current level of fitness and also their life situation (sleep, diet, work/home life etc).
This is to ensure a holistic view to optimise training/performance and reduce the risk of illness. After all, a decrease in salivary IgA and a high cumulative training load can increase the risk of contracting an infection and the chance of missing training days, which can lead to a reduction in performance.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
