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Monthly Health Tips - October 2008

Exercise Intensity

Dan Andrews - Gymnasium Team Leader

Exercise intensity refers to how hard your body is working during physical activity. For maximum health benefits, the goal is to work hard but not too hard. There is a variety of ways to measure your exercise intensity to make sure your body is getting the most out of every workout.

If you have a medical condition, are overweight, are aged over 40 years or haven't exercised regularly in a long time, see your doctor for a medical check-up before starting any new exercise program.

The body's response to exercise

Your body's response to moderate intensity exercise normally includes:

• Faster heart rate
• Faster breathing
• Feeling warmer
• Slight swelling of the hands and feet
• Mild to moderate perspiration
• Mild muscular aches for a day or two afterwards, if you are not used to the physical activity.

Warning signs

If you experience any of the following symptoms, stop exercising and seek medical help:

• Extreme breathlessness
• Breathing problems such as wheezing or coughing
• Chest pain or pressure
• Extreme perspiration
• Dizziness, fainting
• Severe muscle pain or cramps
• Nausea
• Severe pain in any muscles or joints
• Extreme and long-lasting fatigue after exercising.

Measuring exercise intensity

You may need to experiment to find out which method of measuring exercise intensity suits you best. The different measurement methods include:

• Target heart rate
• Talk test
• Exertion rating scales
• Self-monitoring.

Target heart rate

Target heart rates for fitness and health gains are between 40 and 85 per cent of your maximum heart rate (maxHR). Maximum heart rate is calculated as 220 beats per minute (bpm) minus your age. A heart rate monitor is an easy way to keep track of your heart rate while you're exercising.

If you have a medical condition, are overweight, are aged over 40 years or haven't exercised in a long time, see your doctor. Your heart rate target range may need to be professionally recalculated to take your health and general fitness into account.

Some medications can alter your heart rate response to exercise, so make sure you discuss the medications you are taking and how they may affect your exercise plans with your doctor. It may be necessary to use another option for monitoring exercise intensity if you are taking certain medications.

Target heart rate chart

Age (years)	Heart beats per minute target range (40-85% of maxHR)
20	80 - 170
25	78 - 166
30	76 - 152
35	74 - 157
40	72 - 153
45	70 - 149
50	68 - 145
55	66 - 140
60	64 - 136
65	62 - 132

Pulse rate

Taking your pulse at regular intervals lets you know whether you are exercising within your target heart range. Some tips:

• Take your pulse before the warm up.
• Take your pulse again when you've been exercising for about 5-10 minutes. Continue taking your pulse at regular intervals.
• Take your pulse at the end of your activity bout and then again 2-5 minutes after you have stopped exercising - a drop of approximately 12 bpm after you stop activity indicates that your recovery is adequate.

How to measure your pulse

The radial pulse is located on your inner wrist. To measure it, you should:

• Put the first three fingers of one hand against the inner wrist of the other hand just below the thumb.
• Move your fingers slowly across the wrist until you detect a tendon.
• Press your fingers into the hollow next to the tendon on the thumb-side - your artery lies just beneath the skin.
• Don't push too hard when taking your pulse or you'll squash the artery and impede blood flow.
• Using a watch with a second hand, count your pulse for 15 seconds. Multiply this figure by four to get your beats per minute. (For example, 31 pulse beats over 15 seconds equals a pulse rate of 124 beats per minute.)

Factors known to influence heart rate

It's not just exercise that affects your heart rate. Your beats per minute could be raised by a number of internal and external factors including:

• Hot weather
• Caffeine intake
• Time of day
• Hormone fluctuations
• Stress or anxiety
• Cigarette smoking
• Medications.

Talk test

Talking is a reliable way to measure exercise intensity. Suggestions include:

• If you can talk and sing without puffing at all, you're not pushing yourself hard enough.
• If you can comfortably talk but not sing, you're exercising at the right intensity.
• If you can't talk at all without gasping, slow down the pace.

Exertion levels

This method requires you to rate how hard you're working by observing your body's physical signs. Aim to experience the exercise signs 3-7 in the chart below to keep within your target heart rate.

You can keep a diary of your exertion ratings to monitor your fitness progressions. As an activity becomes easier, the rating should decrease and then you know it's time to increase the intensity of the activity.

Level	Exertion	Physical signs
0	None	None
1	Minimal	None
2	Barely there	Sensation of movement
3	Moderate	Stronger sensation of movement
4	Somewhat hard	Warmth or light sweating
5	Hard	Sweating
6	Harder	Moderate sweating
7	Very hard	Moderate sweating, but can still talk
8	Extremely hard	Heavy sweating, can't talk
9	Maximum effort	Very heavy sweating, can't talk
10	Maximum effort	Exhaustion

Self-monitoring

Recent studies show that paying attention to how you feel while you exercise may be one of the most effective ways to measure exercise intensity. Researchers have found that study participants who pushed themselves past their optimum exercise threshold felt uncomfortable.

Signs of discomfort that suggest you're working too hard include:

• Breathlessness
• Muscle weakness and fatigue
• Feeling like you're just not enjoying yourself anymore.

Where to get help

• Your doctor
• Exercise physiologist
• Physiotherapist
• 'Go for your life' Infoline Tel. 1300 739 899 www.goforyourlife.vic.gov.au

Things to remember

• You can measure exercise intensity using target heart rates, the talk test, exertion levels or self-monitoring.
• If you have a medical condition, are overweight, are aged over 40 years or haven't exercised regularly in a long time, see your doctor for a medical check-up before starting any new exercise program and watch out for the warning signs listed above.

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Updated: 1 October 2008