UK GCSE level age ~14-16, ~US grades 9-10 Biology revision notes re-edit 14/05/2023 [SEARCH]

Diet and exercise : 4. Regular aerobic exercise can reduce your risk from some non-communicable diseases

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(4) Regular aerobic exercise can reduce your risk from some non-communicable diseases

  • If you have a high resting heart rate (measured by your 'pulse') and you are slow to recover from physical exercise, you should be aware these observations are linked to an increased risk of developing heart disease (CVD, cardiovascular disease).

    • Regular exercise can reduce your resting heart rate and speed up your recovery rate after engaging in physical activity e.g. brisk walking, manual work, climbing stairs, jogging etc.

    • This has been clearly shown from scientific studies e.g.

    • You take a biggish number of volunteers (say a hundred) that do not exercise regularly.

    • Record their initial baseline resting heart rate.

    • Get them all to do the same physical exercise and record their recovery rate - that is the time it takes for the increased heart rate to fall back to the resting heart rate.

    • You then split the volunteers into two groups and ask one group to do some regular exercise every day e.g. brisk walking for an hour or 20 minutes on an 'aerobic exercise machine', and the other group asked to continue in their normal 'non-aerobic' lifestyle.

    • After, say 2 months, remeasure all their resting heart and recovery rates, and you should find a definite improvement in these figures in the group who did regular extra aerobic exercise.

  • Exercise increases the amount of energy expended by the body.

    • Athletes or people engaged in heavy manual work would need a greater energy (calorie) intake.

      • eg the energy need for cycling at low speed is about 4x that you need for sleeping, and you need 4x the energy for cycling to rapidly climb stairs!

    • Your metabolic rate can stay up even after you have finished engaging in more physical exercise, particularly if it has been strenuous.

    • Regular exercise can increase your metabolic rate because it builds muscle as well as using more energy due to performing more physical activities than just sitting around.

    • People who have more active physical jobs need more energy and hence more carbohydrates or fats ie your dietary needs vary with your occupation.

    • Exercise increases the amount of energy (via fat/carbohydrate etc.) used by the body and so decreases the amount stored as fat, hence less chance of suffering from obesity.

    • Exercise also builds up muscle which boosts your metabolic rate. This includes the diaphragm and intercostal muscles, the crucial muscles used in breathing.

      • Regular exercise also causes an increase in the number and size of the tiny blood vessels in your longs, increasing the efficiency of gas exchange.

    • If you do little exercise and have a job sitting in an office, you should reduce your carbohydrates and fats intake accordingly because you need less energy to get through the day.

    • A note of caution - being fit does not necessarily mean you are healthy, a common assumption! You can be unhealthy because of a lack of balanced diet but you could still be physically non-obese and fit.

The graph shows the pulse rate of Mark and Tony after completing a 20 minute training jog together.

Mark and Tony are about the same weight and both ran the same distance.

After the run they measured their pulse every two minutes i.e. heart beats per minute.

The pulse for Tony falls at a faster rate than Mark, which suggests that Tony has a higher level of fitness than Mark.



INDEX of biology notes on diet and exercise


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