Workout Impact & Credit

Goals

• To provide a behavioural system that can motivate the user in the medium-term.
• To create a 'currency' that allows the user to clearly value workout definitions, activities and combined adaptive responses.
• To provide a progress and levelling-up mechanism.
• To provide an aggregate figure that combines all four types of adaptive response.

Background and strategic fit

The Afterburner workout impact system is closely related to the adaptive response system - in fact it uses the outputs of the adaptive response calculations. The purpose of workout impact is to create an 'training currency' for the user: a single headline figure that they can use to quantify workout definitions, activities and their medium term progress.

More technically, workout impact creates the 'core loop' of the Afterburner game mechanic. It is a double loop, with an inner and outer loop:

The user earns impact credit when they perform a workout activity - this is the inner loop. Then, once they have filled their impact credit bar, they are allowed to take a fitness test, giving them the opportunity to level up to a higher fitness level. Their impact credit then returns to zero and they have completed the outer loop.

Specifications

Here are the key concepts, how they are calculated and how they are communicated:

Workout Impact

Max Workout Impact (MWI)

The max workout impact figure is a property of the workout definition. It is a measure of the maximum total adaptive response that the user would get if they completed the workout now, at their current fitness level.

It is displayed wherever a workout definition is displayed: on the Workout Definition View, Workout Definition List (for each workout) and on the Workout Activity View.

Calculations:

To find the MWI for a workout definition, we calculate the magnitude product for the workout as if it was performed at max intensity. We do this for the cardio and strength responses separately, then average them together. We ignore the other two responses because they do not add any useful information to the picture - a workout will not elicit a metabolic or EPOC response without an equivalent cardio or strength response.

Actual Workout Impact (AWI)

The actual workout impact figure is a property of the workout activity. If is a measure of the total adaptive response that the user actually got when they completed the workout, considering their fitness level and the intensity with which they completed it.

It is displayed wherever a workout activity is displayed: on the Workout Activity View and for each workout activity on the Timeline View.

Calculations:

The AWI is calculated in the same way as the MWI, but uses the intensity from the workout activity instead.

Impact Credit (IC)

The user's impact credit is the sum of all AWI they have earned since their last fitness test. Each time they complete a workout activity, their IC increases and, when they complete a fitness test, their IC is reset to zero.

However, impact credit is not awarded instantly after a workout activity. The AWI from each workout is added to their impact credit bar over time, as the adaptive responses from the activity play out. So therefore, we have a concept of pending IC and realised IC - credit yet to be added to the bar and credit already added to the bar. Note that the IC from multiple workout activities may be being added to the bar at the same time.

Calculations:

To calculate the user's pending and realised impact credit at any given time, we can calculate the pending and realised impact for each workout activity that is still delivering an adaptive response, then sum them up.

To do this, we calculate how much of the response has passed and how much is in the future. We do this for the cardiovascular and strength responses only.

The details of the calculation can be seen in the POC but the outline is:

1. Calculate the 'total response' for cardio by finding the time delta (in hours) where the response 'ends' (reaches 0.01). Do this for strength too.
2. Estimate the area under the response curve between time delta = 0 and the end. Do this for strength too and add them together.
3. Estimate the area under the curve between time data = 0 and now. Do this for strength too and add them together.
4. Use the ratio between these two figures to determine the fraction of actual workout impact that has been realised and is pending.

Impact Credit Attrition

If the user does not complete a workout activity for 7 days, their realised impact credit starts to reduce.

Workout Response Type Fractions

For display and for other calculations, we need to calculate a breakdown of the relative-size of each of the four adaptive responses expected from a workout definition. This breakdown must consider the user's current fitness level - specifically their cardio fitness bias. and therefore must use magnitude products as inputs. The calculation below shows how we do this for the cardiovascular response only:

This data is used to create the workout response type pie charts.

AWI Response Type Breakdown

In addition, we can combine the response type fractions and the AWI to show the specific AWI of a specific response - for cardio for example:

These breakdown figures are shown around the workout response type pie chart on the Workout Activity View.

Requirements

Questions

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

Not Doing