Exercise can help your heart to be healthy

A few recent celebrity deaths led to extreme emotional reactions and almost cast a negative light on exercise activity in general. However, the incidence of exercise-related sudden cardiac death is low and the benefits of regular exercise on both physical health and psychological well-being far outweigh the risks.

The heart is the hub of response to exercise. Exercise increases cardiac output and blood pressure. To meet the demands of skeletal muscle (most muscles of arms, legs, back) blood pumped from the heart should increase and blood flow from inactive organs should get redistributed to active skeletal muscles. While at rest, muscles receive about 20% of the total bloodflow, during exercise, the this increases to more than 80%.

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Longer the duration of exercise, the greater the burden on the heart. For example, a full marathon is more stressful than a 100-metre dash. The lungs are also under stress during exercise as oxygen consumption and carbon dioxide production are increased. Oxygen consumption increases exponentially during the first few minutes of exercise and maximal oxygen uptake is dependent on an individual’s gender, height, weight, lung function, fitness level, genetics and type of activity. Trained athletes can have higher oxygen uptake and consumption because of increased cardiac output and better heart function.

The heat produced by the increased metabolism during exercise must be lost to prevent a dangerous increase in core temperature. When warm blood passes close to the body surface blood vessels dilate and the heat is lost through radiation and conduction. Evaporation of sweat causes fluid and electrolyte loss. Dehydration may lead to impaired cognitive and exercise performance. Neurological adaptations and hormonal changes too matter.

Sports paradox

Exercise-related sudden cardiac death is defined as death happening during or within one hour of physical activity. Age, gender, duration and intensity of physical activity, family history and underlying medical conditions are important factors that determine negative events during exercise.

Serious events including sudden cardiac arrest occurring after sports or exercise are about 5%. In fact, the incidences of heart attacks are significantly lower in persons exercising more than 5 times per week as against sedentary persons exercising less than once per week.

Coronary artery disease is the most common cause. Other causes include hypertrophic cardiomyopathy, dilated cardiomyopathy, myocarditis, arrhythmogenic dysplasias and valvular heart disease.

Inherited genetics, as well as environmental risk factors - diet, lifestyle, and smoking, are considered the reasons. INTER HEART study indicated that the age of onset of disease in parents and whether parents are affected are also valuable.

Exercises for heart health

Aerobic exercises: Improve circulation, thereby reducing blood pressure and heart rate. They increase aerobic fitness, reduce the risk of diabetes. About 30 minutes per day and 5 days a week is good and examples are brisk walk, running, swimming, cycling, and tennis.

Resistance training: Resistance training reduces fat, results in leaner muscle mass. Free weights workouts, hand weights, dumbbells, push-ups, squats are some types of resistance training.

Strength, flexibility and balance: It’s critical to maintain aerobic exercise and resistance training. Flexibility exercises like stretching and yoga should be done daily before and after exercise/workout.

Athletes, persons even in their 30s and 40s wanting to do moderate to heavy exercises need to know their risk factors for developing cardiovascular disease and have those addressed. Given the extensive cardiovascular benefits of exercise, a minimum of 30 minutes of moderately intense physical activity (continuous or 10-minute increments) on most days of the week is recommended. This equals roughly 1.5 miles/day brisk walk.

No doubt, habitual exercise is a “pill” to be taken daily for a healthy life. For improved survival in exercise-related sudden cardiac arrest, the most important factor is the time from collapse to defibrillation (achieve regular rhythm). Advanced life support in the field is the key. Installations of Automated external defibrillators (AEDs) and CPR (cardiopulmonary resuscitation training) programs in exercise facilities/ gyms are recommended.

(The writer is a heart specialist at a hospital based in Mysuru)