Question

While exercising, you can use a heart-rate monitor to sec that your heart rate stays within a safe range suggested by your trainers and doctors. According to the American Heart Association (AHA), the formula for calculating your maximum heart rate in beats per minute is 220 minus your age in years (http://bit. 1y/AHATargetHeartRates). Your tanget beart rate is a range that is \(50-85 \%\) of your maximum heart rate. [Note: These formulas are estimates provided by the AHA. Maximum and target heart rates may vary based on the health, fitness and gender of the individual. Always consult a physician or qualified health care professional before beginning or modifying an exercise program.] Write an app that inputs the person's age, then calculates and displays the person's maximum heart rate and target-heart-rate range.

Short answer

Subtract the person's age from 220 to find the maximum heart rate, then multiply by 0.50 and 0.85 to find the target heart rate range.

Step-by-step solution

Calculate the Maximum Heart Rate

The first step is to calculate the person's maximum heart rate using the formula provided by the American Heart Association (AHA). The maximum heart rate is found by subtracting the person's age from 220. The formula is: \[ \text{Maximum Heart Rate} = 220 - \text{age} \]

Calculate the Target Heart Rate Range

Once the maximum heart rate is determined, the next step is to calculate the target heart rate range, which is 50-85% of the maximum heart rate. This can be calculated using the following two formulas: \[ \text{Lower end of Target Heart Rate} = \text{Maximum Heart Rate} \times 0.50 \] \[ \text{Upper end of Target Heart Rate} = \text{Maximum Heart Rate} \times 0.85 \] These values will give you the suggested target heart rate range during exercise.

Display the Results

Finally, the app should display the person's maximum heart rate and the calculated target heart rate range. These values inform the individual what their heart rate should be when exercising to stay within the safe range suggested by trainers and doctors.

Key concepts

Maximum Heart Rate Calculation

Understanding how to calculate the maximum heart rate (MHR) is crucial for safe and effective exercise. The formula, recognized by the American Heart Association, is a simple subtraction: \( MHR = 220 - \text{age} \). So, if you're 30 years old, your estimated MHR would be \( 220 - 30 = 190 \) beats per minute (bpm).

This formula acts as a foundational guide to ascertain the upper limit of what your heart can handle during physical activity. It's worth noting that this is an estimation, and individual differences such as fitness level, health status, and genetics can influence your true MHR. However, for most individuals, especially those not engaging in high-performance athletics, this calculation is a useful starting point to develop an exercise program.

Target Heart Rate Range

Once you know your maximum heart rate, determining your target heart rate (THR) range is the next step. The THR is the safe intensity zone for your heart during exercise, typically between 50-85% of your maximum heart rate. To find your personal THR, multiply your MHR by 0.50 and by 0.85. For example, with a MHR of 190 bpm, the lower end of your THR is \( 190 \times 0.50 = 95 \) bpm, and the upper end is \( 190 \times 0.85 = 161.5 \) bpm, rounding to the nearest whole number.

Exercising within this range is believed to offer the best cardiorespiratory benefits and it's where you begin to burn fat and improve your aerobic base. It's also a sweet spot for enhancing cardiovascular endurance without overstressing your heart.

Why is There a Range?

The range exists to cater to different exercise intensities and goals. The lower end is more suitable for those just starting or looking for moderate exercise, while the upper end is for more intense sessions.

Exercise Programming

Armed with knowledge of MHR and THR, exercise programming can be tailored to meet personal fitness goals. Whether you're aiming for weight loss, endurance improvement, or general fitness, knowing your heart rate zones helps in structuring your workouts effectively. A balanced exercise program should include warm-up and cool-down phases, which prepare your body and help you recover.

During the main part of the workout, you'll want to fluctuate between different intensities within your THR range. This variety not only makes the exercise more manageable but can also prevent plateaus in progress.

Exercise Improvement Advice

For steady improvements, gradually increase the intensity and duration of your workouts within your THR. This approach, known as progressive overload, challenges your body and promotes fitness adaptations. Avoid jumping into high intensities too quickly, as it may lead to injury or overtraining.