High-G Cardiac Screening Index (Aviation) Calculator

High-G Cardiac Screening Index (Aviation): Explanation and Clinical Context What this calculator does. It implements the Cardiac Force Index (CFI) framework reported in military aircrew: CFI = body weight × activity ÷ heart rate. Using wearable-derived activity at rest and during comfortable walking, the tool outputs RCFI (rest), WCFI (walk), and the Cardiac Force Ratio (CFR = WCFI/RCFI) that summarizes reserve from rest to exertion.

In the study cohort, higher WCFI correlated positively with centrifuge-tested G-tolerance (both relaxed and with anti-G straining). How to enter activity. “Activity” is the device’s dimensionless activity output (e.g., from chest-strap/IMU wearables such as BioHarness). Use stable 1–2 minute segments at rest and during steady walk.

If your device reports “activity counts,” supply those values; keep measurement units consistent between rest and walk. How to interpret results. The table shows your CFI metrics and a tendency category by situating your WCFI relative to the published cohort average (~0.15 ± 0.04).

This is not a diagnosis; rather, it is a screening-style signal of expected G-tolerance tendency to be confirmed with standardized centrifuge protocols and aeromedical assessment. Why not predict exact G-tolerance? The original work reports a positive association between WCFI and centrifuge G-tolerance and discusses thresholds (>5 G relaxed; >8 G straining) probabilistically.

However, full multivariable coefficients and device-specific calibration are required for precise per-person prediction and may vary with hardware, protocol, sex, and training status. Until validated coefficients are universally available, we purposefully provide CFI/CFR and a cohort-anchored tendency rather than a point estimate in Gs. Clinical significance.

For aeromedical screening, CFI/CFR can complement conventional cardiovascular risk assessment and structured centrifuge evaluation. Observational work suggests that exposure to high-G does not generally cause adverse cardiac structural remodeling in trained fighter pilots, though some right-heart functional adaptations may occur. Any abnormal symptoms, arrhythmias, or structural findings should be managed per aviation cardiology standards and the applicable regulator’s guidelines.