Physiological Response Calculations

Goals

• Motivate the user by showing them how their body is responding to exercise.
• Show the user what their physiological response is right now and how it changes over time.
• Display the physiological response they can expect to get from a specific Workout Definition.
• Display the total response they got from completing a Workout Activity

Background and strategic fit

The core feature of Afterburner is to show the user how their body responds to various types of workout. In reality, our bodies respond in many different ways, making us fitter and more healthy. In Afterburner we group these physiological responses into four Response Categories (RCs):

• EPOC (Excess Post-exercise Oxygen Consumption): after intense exercise, your body must replenish the (phosphocreatine, ATP and glycogen) energy stores that were used up during the workout. This causes you to burn calories for a period after exercise. This increased calorie-burn causes you to consume more oxygen and this is how the effect is measured in a lab. The effect is very strong immediately after exercise but tails off quickly to a low level that can last for a couple of days.
• Strength adaptions: putting your muscles under 'exercise stress' creates micro-tears and causes them to adapt by strengthening themselves. This process is called muscular hypertrophy and can occur for up to 72 hours after exercise. Exercises that put a high resistance on a muscle cause a greater physiological response.
• Cardio (aerobic) adaptions: in the same way, putting your heart and cardiovascular system under exercise stress cause them to adapt and strengthen. Your heart muscles get stronger and bigger (cardio hypertrophy) and are able to pump more blood per second; veins and arteries get bigger and are able to handle more blood per second; lung capacity increases as the lungs grow more alveoli and are able to pass more oxygen into the blood.
• Metabolic adaptions: as fitness increases, your body is able to burn fat more effectively. This means fat can be used as the primary fuel at higher exercise intensities, making it easier for you to burn even more fat. The body also becomes better at regulating hormones such as insulin and ghrelin. These are the hormones that govern the body's hunger and fat storage mechanisms.

When a user completes a Workout Activity, we calculate what these four responses will be - in total and over time. Each RC has a 'default shape' when graphed over time. But, depending on the type of exercise performed, the duration, and the level of intensity with which in was performed, the magnitude and duration of each RC is altered. For example, performing push-ups, planks and lunges will elicit a very different set of physiological responses from jumping jacks, running on the spot and step-ups - even if the intensity and duration are the same.

Specifications

The above concepts are communicated to users in Afterburner in the following ways:

1. Pie charts and max impact are shown on Workout Definitions. These communicate the max total response available from performing this workout and the ratio between the RCs. The data comes from the constituent Exercise Definitions and durations.
2. Strength and cardio ratings are shown on Exercise Definitions.
3. When a Workout Activity is complete, the Workout Activity Detail View is presented immediately. This shows total burn and a total for each of the RCs. These totals represent the total response from this workout and they will not change over time.
4. The Afterburn View shows the current response (if any). It shows the current overall response and the current response for each category. These values change over time and are recalculated regularly.

Workout Definitions: RC Pie Chart and Max Impact

The data for the Response Category Pie Chart is calculated by summing all the responses and durations for all the exercises that this Workout Definition contains.

So, if C = ExerciseDefinition.Cardio and D = Exercise.Duration the max total response for a single exercise is:

R₁ = C₁ * D₁

Then we can sum all the exercises to get the total for cardio:

TotalCardio = ∑(R₁ + R₂ + ... + R_n)

Then, we do this for the other three Response Categories and can create a pie chart that will show the ratios between them.

The Max Impact is simply the square root of the sum of the TotalCardio, TotalStrength, TotalMetabolic and TotalEpoc figures from above:

MaxBurn = √(TotalCardio * TotalStrength * TotalMetabolic * TotalEpoc)

Workout Activity Responses

Requirements

Questions

Below is a list of questions to be addressed as a result of this requirements document:

Not Doing