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fitness: add speed-based MET tables for swimming and rowing kcal estimation
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Add SWIMMING_METS and ROWING_METS lookup tables from Ainsworth
Compendium for speed-based calorie estimation when distance+duration
are available. Add per-exercise flat-rate fallbacks (FLAT_RATE map)
instead of hardcoded if/else chains.
This commit is contained in:
Alexander Bocken
2026-03-23 12:37:03 +01:00
parent 1f83b451de
commit 08bd016404
1 changed files with 44 additions and 15 deletions
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59
src/lib/data/cardioKcalEstimate.ts
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@@ -259,6 +259,25 @@ function interpolateMet(table: [number, number][], speedKmh: number): number {
return table[table.length - 1][1];
}
/** Swimming METs by speed (km/h). From Compendium codes 18xxx. */
const SWIMMING_METS: [number, number][] = [
[1.5, 4.8], // light effort, treading
[2.0, 5.8], // moderate, leisure
[2.5, 8.3], // moderate-vigorous, laps
[3.0, 9.8], // vigorous, laps
[3.5, 10.3], // fast, competitive training
];
/** Rowing METs by speed (km/h). From Compendium codes 18xxx / 15xxx. */
const ROWING_METS: [number, number][] = [
[6.0, 3.5], // very light
[8.0, 4.8], // light
[10.0, 5.8], // moderate
[12.0, 7.0], // vigorous
[14.0, 8.5], // very vigorous
[16.0, 12.0], // racing
];
/** Fixed MET values for activities without speed data */
const FIXED_METS: Record<string, number> = {
'swimming': 5.8, // Compendium 18310, moderate effort
@@ -270,6 +289,18 @@ const FIXED_METS: Record<string, number> = {
'cycling-indoor': 6.8, // Compendium 02014, moderate
};
/** Flat-rate kcal/kg/km for distance-only fallback */
const FLAT_RATE: Record<string, number> = {
'running': 1.0, // Léger & Mercier
'walking': 0.7,
'hiking': 0.7,
'cycling-outdoor': 0.3,
'cycling-indoor': 0.3,
'swimming': 1.6, // ~4× rolling resistance of running in water
'rowing-machine': 0.6,
'rowing-outdoor': 0.6,
};
// ── Main cardio estimation interface ─────────────────────────────────────
export interface CardioEstimateResult {
@@ -305,6 +336,8 @@ export function estimateCardioKcal(
const isRunning = exerciseId === 'running';
const isWalking = exerciseId === 'walking' || exerciseId === 'hiking';
const isCycling = exerciseId === 'cycling-outdoor' || exerciseId === 'cycling-indoor';
const isSwimming = exerciseId === 'swimming';
const isRowing = exerciseId === 'rowing-machine' || exerciseId === 'rowing-outdoor';
const isRunOrWalk = isRunning || isWalking;
// 1. GPS-based estimation
@@ -324,22 +357,23 @@ export function estimateCardioKcal(
if (distanceKm && distanceKm > 0 && durationMin && durationMin > 0) {
const speedKmh = distanceKm / (durationMin / 60);
if (isRunning) {
const met = interpolateMet(RUNNING_METS, speedKmh);
/** @type {[number, number][] | null} */
let metTable: [number, number][] | null = null;
if (isRunning) metTable = RUNNING_METS;
else if (isCycling) metTable = CYCLING_METS;
else if (isSwimming) metTable = SWIMMING_METS;
else if (isRowing) metTable = ROWING_METS;
if (metTable) {
const met = interpolateMet(metTable, speedKmh);
const kcal = met * bodyWeightKg * (durationMin / 60) * 1.05;
return withUncertainty(kcal, 0.20, 'met-speed');
}
if (isWalking) {
// Walking: ~3.5 METs at 5 km/h, scales roughly with speed
const met = Math.max(2.0, 0.7 * speedKmh);
const kcal = met * bodyWeightKg * (durationMin / 60) * 1.05;
return withUncertainty(kcal, 0.20, 'met-speed');
}
if (isCycling) {
const met = interpolateMet(CYCLING_METS, speedKmh);
const kcal = met * bodyWeightKg * (durationMin / 60) * 1.05;
return withUncertainty(kcal, 0.20, 'met-speed');
}
}
// 3. Duration only → fixed MET
@@ -367,13 +401,8 @@ export function estimateCardioKcal(
// 4. Distance only → flat-rate kcal/kg/km
if (distanceKm && distanceKm > 0) {
let kcalPerKgPerKm: number;
if (isRunning) kcalPerKgPerKm = 1.0; // Léger & Mercier
else if (isWalking) kcalPerKgPerKm = 0.7; // walking on flat
else if (isCycling) kcalPerKgPerKm = 0.3; // rough cycling estimate
else kcalPerKgPerKm = 0.8; // generic cardio
const kcal = kcalPerKgPerKm * bodyWeightKg * distanceKm;
const rate = FLAT_RATE[exerciseId] ?? 0.8;
const kcal = rate * bodyWeightKg * distanceKm;
return withUncertainty(kcal, 0.30, 'flat-rate');
}