Influenza & The Endurance Athlete

When it comes to the
influenza virus there's almost
nowhere to hide.

"I am sick and tired of being sick and tired."  ~Fannie Lou Hamer

Have you noticed that "something's going around" lately?  There's a better than average chance that you or a training partner has been sidelined with an illness in the last four weeks.  While athletes are generally the healthiest and heartiest in a population, they too are susceptible to catching what's going around and this time of year that generally means the flu.

According to the Center's for Disease Control and Prevention, influenza (the flu) is a contagious respiratory illness caused by influenza viruses.  While there are four types of the virus (A, B, C, & D), human influenza viruses A & B are responsible for seasonal epidemics almost every winter.   Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus;  the hemagglutinin (H) and the neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase sub types. (H1 through H18 and N1 through N11 respectively.)  Influenza A viruses can be further broken down into different strains. Current subtypes of influenza A viruses found in people are influenza A (H1N1) and influenza A (H3N2) viruses. *adapted from the CDC

The Flu Virus In Action
From the CDC

How It Spreads  
Scientists believe that influenza viruses spread mainly by tiny droplets made when people with the flu cough, sneeze, or talk. These droplets can land in the mouths or noses (ie. respiratory system) of people who are less than six feet away. Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose, or even their eyes.  Most healthy adults may be able to infect other people beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children may pass the virus for longer than 7 days. Symptoms start 1 to 4 days after the virus enters the body. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Some people can be infected with the flu virus but have no symptoms. During this time, those persons may still spread the virus to others.  *adapted from the CDC

What Are The Symptoms?  
People who have the flu often feel some or all of these signs and symptoms that usually start suddenly, not gradually:

• Fever* or feeling feverish/chills (*not everyone with the flu will have a fever)
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue (very tired)
• Some people may have vomiting and diarrhea, though this is more common in young children than in adults.

*adapted from the CDC

"The Flu Season"
From the CDC

The Impact To Endurance Athletes
While there are no ideal times to be sick, there are certainly times that are worse than others.  According to the CDC, the peak months for flu activity are December through March.  This time period represents important sport-specific preparation for spring events including marathons.  During this time every training unit is critical as volume is gradually increased toward key benchmarks.  Missing a single training unit will have little impact on the accumulation of fitness, but missing a week or more of training may result in a setback and prompt revisions to the training plan and reassessment of goals.  

Preventing The Flu
The CDC recommends a yearly flu vaccine as the initial and most important step in protecting against flu viruses.  As discussed earlier, there are many subtypes of the virus and all can cause influenza.  Scientist develop the vaccine each year to handle what is estimated to be the most common type(s), but it is never a guaranteed measure against getting sick.  Athletes should also consider the following every day practices to reduce the likelihood of getting the flu;

• Try to avoid close contact with known sick people.
• Limit the time spent in close contact with large groups of people.
• Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub.
• Avoid touching your eyes, nose and mouth.
• Clean and disinfect surfaces and objects that may be contaminated with germs like the flu.

Once You're Sick

Despite getting the flu shot and practicing good prevention measures, athletes sometimes get sick.  Identifying and dealing with the illness appropriately may lessen the burden on those within your immediate environment and help you return to training safely and effectively.

If during the months of December through March the symptoms listed above come on suddenly following exposure to individuals with known influenza there is a very good chance you have also contracted it.  Although because there are other respiratory illnesses that can also cause flu-like symptoms it's virtually impossible to diagnose the virus without a test.  Therefore, flu-like illnesses in otherwise healthy athletes are essentially handled the same way.

Most athletes with the flu (or other flu-like illnesses) have a mild illness and do not require medical attention or anti-viral medications.  If you do get sick in most cases it's best to stay home, rest, and avoid contact with other people.  Some individuals are considered high risk for developing flu-related complications and should consult their healthcare providers as soon as symptoms develop.  A full list may be found on the CDC website.

In an effort to lessen the burden on others and hasten your return to activity, it's wise to follow these practices when you're sick with flu-like symptoms;

• While sick, limit contact with others as much as possible to keep from infecting them.
• If you are sick with flu-like illness, the CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. (Your fever should be gone for 24 hours without the use of a fever-reducing medicine.)
• Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Remain adequately hydrated.  Urine should be pale yellow color.
• Hold all training activities for at least 24 hours after your fever is gone or symptoms have subsided.

Returning To Training

Once symptoms have gone and you're feeling back to yourself, the next challenge is determining the safest and most effective way to return to training.  Prolonged bed rest (30 days or greater) may have a profound effect on the cardiovascular, muscular, and skeletal systems.  These changes may include reductions in VO2max, skeletal muscle force production, and bone density.  Any illness causing bed rest of this duration should result in the complete redesign of a training plan to start from square zero.  The initial priority is the safe resumption of every day physical activity to eventually include a very low volume exercise program.  This approach may take up to six months to prepare an athlete to begin a structured and more rigorous training plan.

Most layoffs for endurance athletes however are a week or less in duration.  Nevertheless, the physiologic degradation of the cardiovascular, muscular, and skeletal systems happens on a continuum and should be considered when resuming training.  It may be assumed that early remodeling of the cardiovascular and muscular systems will be of greatest importance to the endurance athlete returning to training.  If you've been "in bed" with flu-like symptoms for a week or less it may be wise to consider the following return to training guidelines;

• Missed training units should remain missed, do not push them ahead in the plan.
• The first endurance-type training unit performed after a layoff should be an active recovery or easy training unit.  Avoid higher intensity workouts on the initial day back to training.
• Strength training may need to be modified to reduce the volume by decreasing the intensity (ie. amount of weight lifted).

It takes a considerable amount of time off from training to result in significant decreases in fitness so many athletes may find their return to training fairly uneventful.  That said, it is still important to lower performance expectations in the 7-14 days following a typical layoff while physiologic adaptations occur.