Heart rate and its role in exercise

Heart rate is the number of times your heart beats per minute, measured in beats per minute (bpm). It provides a key indicator of how hard your body is working during physical activity. As you exercise, your heart rate rises to pump more blood and deliver increased oxygen to your muscles.

The more intense the exercise, the higher your heart rate will climb. Monitoring heart rate helps ensure you train at the right intensity to achieve specific fitness goals.

Maximum heart rate

Maximum heart rate (MHR) is the highest number of beats per minute your heart can reach during intense exercise. It serves as a baseline for determining safe and effective training intensities, as it varies based on factors like age.

Formula for maximum heart rate

$\text{MHR}=220-\text{age}$

Where:

• MHR = Maximum heart rate (bpm)
• Age = Your age in years

This formula provides an estimate.

Worked example - Calculating maximum heart rate

A 30-year-old athlete wants to find their maximum heart rate to plan training sessions. Calculate the MHR using the formula.

Step 1: Identify the values

Age = 30 years

Step 2: Apply the formula

$\text{MHR}=220-30$

Step 3: Calculate the MHR

$\text{MHR}=190\text{ bpm}$

Step 4: Interpretation

This means the athlete's heart should not exceed 190 bpm during maximum effort exercise, and training zones can be based on percentages of this value.

Aerobic and anaerobic activities

Physical activities can be classified based on how the body produces energy. Aerobic activity relies on oxygen to generate energy, while anaerobic activity produces energy without oxygen.

Key differences between aerobic and anaerobic activities

• Aerobic activity - This means "with oxygen" and involves steady, prolonged efforts where the body uses oxygen to break down fuels for energy.
• Anaerobic activity - This means "without oxygen" and occurs during high-intensity efforts where energy is produced quickly.

Target zones for training

Target zones are specific heart rate ranges that guide training intensity to target either aerobic or anaerobic fitness improvements. They are expressed as percentages of your maximum heart rate.

Training thresholds refer to the lower and upper boundaries of these zones. Beginners should aim for the lower threshold, while experienced athletes can push towards the upper threshold.

Aerobic target zone

The aerobic target zone focuses on building endurance and is typically 60%-80% of maximum heart rate.

Anaerobic target zone

The anaerobic target zone targets power and speed development and is usually 80%-90% of maximum heart rate.

Calculating aerobic target zones

To train effectively in the aerobic zone, you need to calculate the specific heart rate range based on your maximum heart rate.

Steps to calculate aerobic target zone:

1. Calculate maximum heart rate using MHR = 220 - age.
2. Find the lower threshold by multiplying MHR by 0.6 (60%).
3. Find the upper threshold by multiplying MHR by 0.8 (80%).
4. The target zone is the range between these two values (in bpm).

Worked example - Calculating aerobic target zone

A 40-year-old beginner runner wants to determine their aerobic target zone for endurance training. Calculate the zone using the provided steps.

Step 1: Calculate maximum heart rate

Age = 40 years

$\text{MHR}=220-40=180\text{ bpm}$

Step 2: Calculate lower threshold

$\text{Lower threshold}=180\times 0.6=108\text{ bpm}$

Step 3: Calculate upper threshold

$\text{Upper threshold}=180\times 0.8=144\text{ bpm}$

Step 4: Determine the target zone

The aerobic target zone is 108-144 bpm. Training within this range will help build aerobic fitness safely for a beginner.

Applying training zones to different sports

Training intensity should align with the demands of your chosen activity. Different sports emphasise aerobic or anaerobic elements, or a combination, so selecting the right target zone is essential.

Training for aerobic-dominant activities

For sports like long-distance cycling or marathon running, focus on the aerobic target zone (60%-80% of MHR).

Training for anaerobic-dominant activities

Activities such as sprinting or high-intensity interval training benefit from the anaerobic target zone (80%-90% of MHR). This enhances muscle power, increases tolerance to lactic acid, and improves the body's ability to clear it.

Training for mixed activities like team sports

Team sports, such as basketball or football, involve both continuous movement (aerobic) and short bursts of speed or power (anaerobic). A balanced training programme combining both zones is recommended.