Physiological Health Indicators
What Are Physiological Indicators?
Physiological indicators are measurable physical signs that health professionals use to assess a person’s current state of health. They provide objective data — actual numbers that can be compared against published guidelines to determine whether someone is healthy or at risk. The Component 3 specification requires you to know four key indicators: resting heart rate, heart rate recovery after exercise, blood pressure, and body mass index (BMI).
Understanding these indicators is important because they allow health professionals to identify health risks early, before symptoms develop. Abnormal readings can be a warning sign of underlying conditions that need attention.
Resting Heart Rate
Resting heart rate (also called resting pulse) measures how many times the heart beats per minute when the body is completely at rest. The normal range is 60 to 100 bpm (beats per minute).
Normal resting heart rate: 60 to 100 bpm. A lower resting heart rate generally indicates better cardiovascular fitness, as the heart pumps more blood per beat. Athletes may have resting rates below 60 bpm.
A resting heart rate that is consistently above 100 bpm (tachycardia) may indicate stress, anxiety, dehydration, anaemia, thyroid problems, or heart conditions. It means the heart is working harder than it should, which over time can increase the risk of heart failure. A rate consistently below 60 bpm (bradycardia) in a non-athlete may indicate problems with the heart’s electrical system and can cause dizziness, fatigue, and fainting.
Heart Rate Recovery After Exercise
Heart rate recovery measures how quickly the heart returns to its resting rate after physical activity. The faster the recovery, the fitter the individual. A healthy person’s heart rate should drop significantly within the first minute after stopping exercise — typically by at least 15 to 25 bpm.
Slow heart rate recovery is a sign of poor cardiovascular fitness and may indicate an increased risk of heart disease. If someone’s heart takes several minutes to return to normal, it suggests the heart and circulatory system are not functioning efficiently. This indicator is useful because it shows how well the body copes under stress — not just at rest.
Blood Pressure
Blood pressure measures the force of blood against the walls of the arteries. It is recorded as two numbers: systolic (pressure when the heart beats) over diastolic (pressure when the heart rests between beats), measured in mmHg.
Low blood pressure: 90/60 mmHg or lower. Can cause dizziness, fainting, and fatigue. May indicate dehydration, blood loss, or an underlying medical condition.
Ideal blood pressure: Between 90/60 mmHg and 120/80 mmHg. The heart and blood vessels are functioning well.
Pre-high blood pressure: Between 120/80 mmHg and 140/90 mmHg. A warning sign that lifestyle changes are needed to prevent progression to high blood pressure.
High blood pressure (hypertension): 140/90 mmHg or higher. Often called the “silent killer” because it usually has no symptoms but significantly increases the risk of heart attack, stroke, and kidney disease.
High blood pressure is particularly dangerous because most people do not know they have it. Risk factors include obesity, high salt intake, lack of exercise, stress, smoking, and excessive alcohol consumption. It can be managed through lifestyle changes (diet, exercise, reducing salt) and medication.
Body Mass Index (BMI)
BMI is a calculation used to estimate whether a person is a healthy weight for their height. It is calculated by dividing weight in kilograms by height in metres squared: \(\text{BMI} = \frac{\text{weight (kg)}}{\text{height (m)}^2}\).
Underweight: Below 18.5 kg/m². May indicate malnutrition, eating disorders, or underlying illness. Risks include weakened immune system, osteoporosis, and fertility problems.
Healthy weight: Between 18.5 and 24.9 kg/m². Lower risk of weight-related health problems.
Overweight: Between 25 and 29.9 kg/m². Increased risk of type 2 diabetes, CVD, and joint problems.
Obese: Between 30 and 39.9 kg/m². Significantly increased risk of serious health conditions.
Severely obese: 40 kg/m² or above. Very high risk of life-threatening conditions including heart disease, stroke, and some cancers.
BMI has limitations. It does not distinguish between muscle and fat — a muscular athlete may have a high BMI but be very healthy. It also does not show where fat is stored (abdominal fat is more dangerous than fat on the hips). Despite these limitations, BMI remains a widely used screening tool because it is quick, cheap, and provides a useful starting point for health assessments.
Significance of Abnormal Readings
The specification requires you to understand the significance of abnormal physiological readings in terms of both short-term risks (impact on current physical health) and long-term risks (potential future health problems).
Short-term risks of abnormal readings include dizziness, fatigue, breathlessness, and fainting. Long-term risks include heart attack, stroke, kidney disease, type 2 diabetes, and reduced life expectancy.
For example, high blood pressure in the short term may cause no noticeable symptoms (hence “silent killer”), but in the long term it significantly increases the risk of heart attack, stroke, kidney failure, and vision problems. A high BMI in the short term may cause breathlessness and joint pain, while in the long term it increases the risk of type 2 diabetes, CVD, and some cancers.