How Injury Guardian applies the Banister Theorem to Strava data

Platforms like Strava collect large amounts of training data. However, raw data alone is not enough to prevent injuries or optimize performance.

Injury Guardian applies the Banister Theorem to transform Strava activities into actionable indicators of training load, fatigue, fitness, and injury risk for runners.

From Strava data to training load analysis

Activities considered

Injury Guardian currently analyzes running activities only. This ensures physiological consistency and more reliable training load interpretation.

Training Load (TL) calculation

Training Load is the foundation of all Banister-based indicators. It is calculated using running distance and average speed.

Elevation gain is not yet included in the calculation, meaning training load is currently estimated from horizontal effort only.

A relative and personalized load

Average speed is compared to an athlete-specific baseline derived from Strava history, making training load fully relative and individualized.

Applying the Banister model: ATL and CTL

ATL – Acute Training Load

ATL represents recent training load. It is calculated over the last 7 days and reflects short-term fatigue.

CTL – Chronic Training Load

CTL represents long-term training load. It is calculated over the last 42 days and reflects overall fitness.

From TSB to injury risk score

The ATL / CTL ratio, also known as TSB, represents the balance between fatigue and fitness. Rapid increases in this ratio are associated with higher injury risk.

Injury Guardian converts this ratio into an injury risk score ranging from 0 to 100, directly proportional to the observed imbalance.

A score always relative to the athlete

Injury risk scores are strictly individual. A score of 70 does not represent the same training stress for an elite athlete as it does for a recreational runner.

Current limitations and future improvements

The current model does not yet include elevation, perceived exertion (RPE), or external factors such as sleep and stress. These elements are part of future development plans.

Conclusion

Injury Guardian turns Strava data into meaningful training insights, applying the Banister Theorem to help runners progress safely and sustainably.