You too could have the heart and lungs of an athlete, all it takes is training. Heart muscle is much like any other, you can develop it with exercise. Top athletes increase the size of their heart by as much as 25 percent.
The chambers of athletes' hearts get larger and stronger in order to pump more blood to their arm and leg muscles and feed them with extra oxygen. But you don't have to be an athlete to benefit from exercise. Anyone who exercises regularly will reduce the risk of heart disease.
The normal resting heart rate is between 65 and 80 beats per minute, rising as high as 200 or more with exercise. You can calculate the maximum rate your heart is capable of by subtracting your age from 220. Thus, a 40-year-old's maximum rate should be 180. But don't expect to reach this. You should aim to achieve a level of exercise which keeps it at 70-80 percent of maximum. Recovery is also important.
Having reached your target heart rate it should take as little as two minutes after you stop to bring it down to around the 100 mark. It will then take rather longer for it to return to normal.
The purpose of training is to improve your fitness by increasing the amount of activity you can perform at any given heart rate. Athletes have resting heart rates as low as 40 or 50, going down to a remarkable 25 to 30 when they are asleep.
And to get their rate up as high as 180 would take far more intensive activity than for the average person.
The output of the heart depends not only on how fast it is beating but on how much blood is pumped out each time it contracts.
As athletes' hearts get bigger, they start to pump out more blood per beat. This is clearly much more efficient than simply increasing the heart beat till it is going so fast it does not have time to fill properly with blood.
But you can develop the size of your heart without heavy training. Many only relatively fit people will have a heart some 10 percent bigger than average.
The "four-limb" sports, such as rowing and cross-country skiing, seem to be especially good for the heart. When all four limbs are active, more blood is pushed back to the heart than when you are using just your arms or your legs.
While the hearts of elite athletes look better than those of the rest of us, their lungs are much the same in terms of size; they also have roughly the same number of tubes and air sacs.
What makes them superior is their ability to take in air and extract oxygen.
At a resting 15 breaths a minute, you can expect to take in about 12 liters of air, from which you will extract about 200ml of oxygen.
Exercising flat out, a top-class athlete would expect to increase his respiration rate to around 40 to 60 breaths a minute, taking in 100-150 liters of air and extracting about five liters of oxygen a minute.
The muscles of the arms and legs use the oxygen to produce energy - roughly five calories of energy for every liter of oxygen.
Photo: 500 Calories
This is how fitness experts are able to tell you that lying down, for example, you expend two calories of energy a minute, sitting three calories, walking four calories and running upwards of five.
It is not till you have been running for half an hour that you use up about 500 calories, which is roughly equivalent to the calorific value of a low calorie, prepacked frozen dinner.
If you want to lose weight you are better off performing a lower-grade form of exercise such as walking or golf. You have a lower rate of energy expenditure but since you are doing it for so much longer the total number of calories used up is much more.
So what are the possible dangers of overdoing it?
You cannot strain a healthy heart even with very strenuous exercise. If it reaches the point where it cannot pump any harder there won't be enough oxygen getting into the muscles.
They will fatigue and you will have to stop. The danger occurs if you over-exercise with an unhealthy heart.
It can take only three half-hour sessions of exercise a week for three to six months to build up a powerful heart and lungs. But keep up the routine, it takes about the same period of inactivity to lose it all.