Dear Dr. B: My friend and I go to a gym regularly. At the end of a strenuous session my friend feels nauseated. What is the reason?
Answer: Regular exercise has many benefits. Those benefits are achieved if the exercise is done properly. Otherwise, exercise may harm you. Let us try and understand what happens when we exercise.
Exercise considerably increases muscle metabolism (break down of substances to yield energy). To meet this increased metabolic activity, muscles require more nutrition and more oxygen. Blood carries nutrition and oxygen to the muscles. That means more blood is pooled to the muscles at the expense of other vital organs.
The body responds to this need immediately. The body ensures that the metabolic needs of exercising muscles are met, that hyperthermia (overheating) does not occur, and that blood flow to essential organs is protected.
This protective mechanism is achieved by the circulatory system (heart and blood vessels). It involves a complex series of adjustments resulting in a large increase in cardiac output (blood flowing out of the heart) proportional to the increased metabolic demands. The increased metabolic activity rapidly increases the heart rate.
During a tough workout in a hot environment, the body can lose two liters of fluid per hour through sweat. There is also loss of electrolytes. This can result in severe dehydration which can be dangerous.
Hyperthermia can be a problem as well. It causes lightheadedness, nausea, headache, hyperventilation, fatigue, and loss of concentration. Heatstroke is the most dangerous complication of hyperthermia.
Those who use anabolic steroids to stimulate production of muscle tissue are also at an increased risk of complications.
What are the other dangers of strenuous exercise?
Heart attack and sudden death from strenuous exercise has been reported. One American report says that an estimated 1.5 million heart attacks occur every year; of these, 75,000, or about five percent, occur after heavy exertion, leading to 25,000 deaths.
Strenuous exercise or high-impact aerobics can cause injuries to bones and muscles.
High-impact exercise can also damage the inner ear, causing dizziness, ringing in the ear, motion sickness, or loss of high-frequency hearing.
The risk factors which are associated with complications during exercise are age, presence of heart disease and intensity of exercise.
How can you exercise safely?
Most important thing is to listen to warning signs. It is estimated that at least 40 percent of young men who die suddenly during a workout have previously experienced, and ignored, warning signs of heart disease: irregular heartbeat, undue shortness of breath, chest pain and weakness.
Be careful to warm up, cool down, and stretch; flexibility is the key to preventing many muscle strains. Vary training and alternate easy and harder workouts.
Don’t eat two hours before vigorous exercise. Drink plenty of fluids before, during, and after a workout. Adjust activity according to the weather and reduce it when fatigued or ill.
When exercising, listen to the body’s warning symptoms, and consult a physician if exercise induces chest pain, irregular heartbeat, undue fatigue, nausea, unexpected breathlessness, or light-headedness.
My advice to your friend is to review his exercise regime, listen to bodys warning signs and symptoms and consult a physician.
Finally, it is February. It is Heart Month. Today is Valentines Day. Let me wish you all a Happy Valentines Day. Take care of your own hearts and the hearts of your loved ones! And support Heart and Stroke Foundation.
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