Its surprisingly difficult to find a calorie calculation for Java for performing a number of steps at a certain speed. Based on the Compendium of Physical Activities (https://sites.google.com/site/compendiumofphysicalactivities/corrected-mets ) and using Corrected METS, I have converted the formulas on their website into Java code! I found the website particularly difficult to read as it did not have brackets in the right places to ensure that the calculations were correct. Hopefully I can save someone the hassle of having to wonder what is going on with all their formulas.
/**
* Calculated the energy expenditure for an activity. Adapted from the following website https://sites.google.com/site/compendiumofphysicalactivities/corrected-mets
*
* @param height The height in metres.
* @param age The date of birth.
* @param weight The weight of the user.
* @param gender The gender of the user.
* @param durationInSeconds The duration of the activity in seconds.
* @param stepsTaken The steps taken.
* @param strideLengthInMetres The stride length of the user
* @return The number of calories burnt (kCal)
*/
public static float calculateEnergyExpenditure(float height, Date age, float weight, int gender, int durationInSeconds, int stepsTaken, float strideLengthInMetres) {
float ageCalculated = getAgeFromDateOfBirth(age);
float harrisBenedictRmR = convertKilocaloriesToMlKmin(harrisBenedictRmr(gender, weight, ageCalculated, convertMetresToCentimetre(height)), weight);
float kmTravelled = calculateDistanceTravelledInKM(stepsTaken, strideLengthInMetres);
float hours = UnitConverter.convertSecondsToHours(durationInSeconds);
float speedInMph = UnitConverter.convertKilometersToMiles(kmTravelled) / hours;
float metValue = getMetForActivity(speedInMph);
float constant = 3.5f;
float correctedMets = metValue * (constant / harrisBenedictRmR);
return correctedMets * hours * weight;
}
/**
* Gets a users age from a date. Only takes into account years.
*
* @param age The date of birth.
* @return The age in years.
*/
private static float getAgeFromDateOfBirth(Date age) {
Calendar currentDate = Calendar.getInstance();
Calendar dateOfBirth = Calendar.getInstance();
dateOfBirth.setTime(age);
if (dateOfBirth.after(currentDate)) {
throw new IllegalArgumentException("Can't be born in the future");
}
int currentYear = currentDate.get(Calendar.YEAR);
int dateOfBirthYear = dateOfBirth.get(Calendar.YEAR);
int age2 = currentYear - dateOfBirthYear;
int currentMonth = currentDate.get(Calendar.MONTH);
int dateOfBirthMonth = dateOfBirth.get(Calendar.MONTH);
if (dateOfBirthMonth > currentMonth) {
age2--;
} else if (currentMonth == dateOfBirthMonth) {
int currentDay = currentDate.get(Calendar.DAY_OF_MONTH);
int dateOfBirthDay = dateOfBirth.get(Calendar.DAY_OF_MONTH);
if (dateOfBirthDay > currentDay) {
age2--;
}
}
return age2;
}
public static float convertKilocaloriesToMlKmin(float kilocalories, float weightKgs) {
float kcalMin = kilocalories / 1440;
kcalMin /= 5;
return ((kcalMin / (weightKgs)) * 1000);
}
public static float convertMetresToCentimetre(float metres) {
return metres * 100;
}
public static float calculateDistanceTravelledInKM(int stepsTaken, float entityStrideLength) {
return (((float) stepsTaken * entityStrideLength) / 1000);
}
/**
* Gets the MET value for an activity. Based on https://sites.google.com/site/compendiumofphysicalactivities/Activity-Categories/walking .
*
* @param speedInMph The speed in miles per hour
* @return The met value.
*/
private static float getMetForActivity(float speedInMph) {
if (speedInMph < 2.0) {
return 2.0f;
} else if (Float.compare(speedInMph, 2.0f) == 0) {
return 2.8f;
} else if (Float.compare(speedInMph, 2.0f) > 0 && Float.compare(speedInMph, 2.7f) <= 0) {
return 3.0f;
} else if (Float.compare(speedInMph, 2.8f) > 0 && Float.compare(speedInMph, 3.3f) <= 0) {
return 3.5f;
} else if (Float.compare(speedInMph, 3.4f) > 0 && Float.compare(speedInMph, 3.5f) <= 0) {
return 4.3f;
} else if (Float.compare(speedInMph, 3.5f) > 0 && Float.compare(speedInMph, 4.0f) <= 0) {
return 5.0f;
} else if (Float.compare(speedInMph, 4.0f) > 0 && Float.compare(speedInMph, 4.5f) <= 0) {
return 7.0f;
} else if (Float.compare(speedInMph, 4.5f) > 0 && Float.compare(speedInMph, 5.0f) <= 0) {
return 8.3f;
} else if (Float.compare(speedInMph, 5.0f) > 0) {
return 9.8f;
}
return 0;
}
/**
* Calculates the Harris Benedict RMR value for an entity. Based on above calculation for Com
*
* @param gender Users gender.
* @param weightKg Weight in Kg.
* @param age Age in years.
* @param heightCm Height in CM.
* @return Harris benedictRMR value.
*/
private static float harrisBenedictRmr(int gender, float weightKg, float age, float heightCm) {
if (gender == Entity.GENDER_FEMALE) {
return 655.0955f + (1.8496f * heightCm) + (9.5634f * weightKg) - (4.6756f * age);
} else {
return 66.4730f + (5.0033f * heightCm) + (13.7516f * weightKg) - (6.7550f * age);
}
}