Tips on Exercising Through The Common Cold
Endurance sports pose a unique problem during the winter months. Colder temperatures, wind, snow and slippery surfaces can create adventurous training conditions and lead to injuries or upper respiratory tract infections. Even with the excellent quality of outdoor underclothing, fighting off the common cold after you are cold and wet can be challenging.
The key to training through an upper respiratory tract infection (URTI) is not to catch it in the first place. Besides frequent hand washing and avoidance of anyone you know with a runny nose, some over-the-counter supplements can boost your immune system to help combat the common cold.
Zinc supplementation of 10 mg per day has been shown through some studies to decrease the severity and duration of URTIs in endurance athletes. Mild zinc deficiency has been postulated in these athletes and supplementation may be beneficial if started within 24 hours of an URTI. Evidence for daily prophylaxis against URTIs with zinc is less compelling and may not be effective unless you are zinc deficient in your diet. High dose supplementation of zinc is associated with suppression of the immune system, therefore doses above 10mg-15mg per day should be avoided.
Glutamine is an essential amino acid that serves as a metabolic fuel for lymphocytes and macrophages (types of white blood cells) and appears to help athletes fight off an URTI. Decreases in plasma levels of glutamine following prolonged endurance exercise have been found in many studies. Prolonged exercise has also been associated with an increased incidence of URTIs in the week or two following a marathon. It is thought that decreased plasma concentration of glutamine post exercise creates a depression of immune function and an increased risk for URTIs. Although studies are controversial in regards to enhanced immune function with supplementation of 100 mg per day, there is little downside to its use. Glutamine has minimal side effects and appears to enhance muscle recovery after prolonged exercise.
Finally, Echinacea dosed at 900mg per day is effective in fighting off the earlier stages of an URTI. Most Echinacea supplements found in our local pharmacies are 100mg -150mg capsules and the package insert recommends 400mg-500mg per day. Well done studies out of Germany, where herbal medications are prescription only and closely monitored by their equivalent of the FDA, found that doses of 900mg per day decrease the severity and duration of URTI symptoms. They also found that daily prophylaxis was ineffective.
For those endurance athletes that still find themselves catching multiple URTIs during the winter season, understanding the basic immune responses to training can help you prevent an URTI. During exercise, epinephrine (adrenaline) is released to help increase cardiac performance, liver metabolism of sugars and bronchial dilation in the lungs. Epinephrine also increases circulating levels of granulocytes (neutrophils, natural killer cells) and T-cell mediated immunity. After exercise, plasma levels of epinephrine drop down to normal resting levels. However, 30 minutes after exercise the level of granulocytes drops to well below normal baseline levels. This significant drop in immune surveillance creates a vulnerable period in which risk for an URTI is increased. During this period (2-6 hours following exercise), keeping warm and dry, hydrated, fueled and away from sick contacts are critical to staying healthy.
Some simple rules do apply to training with an URTI. If you have a fever (greater than 99.0) you shouldn’t train. Many athletes have learned this lesson the hard way. Training through a viral URTI with a fever can increase your risk for a viral infection of the heart such as pericarditis or myocarditis. These heart infections can be caused by viruses that cause the common cold, mononucleosis and/or influenza. Viral infection and inflammation to the pericardial sac surrounding the heart (pericarditis) which causes chest pain and shortness of breath and typically resolves with rest and anti-inflammatory drug such as ibuprofen. Myocarditis is a viral infection of the muscular tissue of the heart causing decreased exercise tolerance, shortness of breath and chest pain. In most cases myocarditis is reversible, but it occasionally causes long term disability. Although these are rare complications of a URTI, clinically I see about 2-3 cases per year.
Another hint is to follow your first of morning heart rate. If you know what your normal AM awaking heart rate (AHR) is, you can make adjustments to your training plan. If you notice a jump of 5 or more beats to your AHR, you might want to cut back on your training volume for a couple of days to help fight off infection. If you are currently symptomatic for an URTI and you have a normal temp and AHR, it is generally safe to train. The only hitch to this much generalized rule is when you are developing a pronounced cough or have chest tightness with inspiration. If you have been coughing more than 3 weeks and don’t seem to be getting better, stop training and see your doctor.
For those with asthma or exercise induced asthma (EIA) you should see your doctor if you notice a drop in your peak flows, have any wheezing or shortness of breath, and if you’re just not getting better after 7- 10 days. For those who develop exercise induced bronchospasm (coughing until you think you might vomit) you’ll need to be started on an albuterol inhaler 30 minutes prior to exercise. Occasionally, inhaled steroids and/or antibiotics are needed for severe or prolonged cases of EIA or EIB.
For those athletes or fitness junkies that are training seriously for competition and can’t afford to take more than several days off from training, you may need to adjust your training schedule. As a general rule, drop the intensity of your workouts during the recovery phase of a cold or flu and cut your training volume to about half of your predicted schedule. Pace training or interval training should be limited or avoided until your heart rate returns to your normal AM resting level.