R/muscle.R

In MarijnJABoer/befitteR: A bundle of health, fitness, food and body related equations, formula's and more, so you can become fit

#' @title Calculate muscle mass
#'
#' @description
#' \lifecycle{stable}
#'
#' Calculate muscle mass in kg.
#'
#' @param height height in cm.
#' @param sex `male` or `female`.
#' @param fg forearm girth in cm.
#' @param cg calf girth in cm.
#' @param c_skinfold calf skinfold.
#' @param tg thigh girth in cm.
#' @param t_skinfold thigh skinfold.
#'
#' @details Martin, A.D., Spenst, L.F., Drinkwater, D.T. and Clarys, J.P.
#' (1990) Anthropometric estimation of muscle mass in men. Medicine and Science
#' in Sports and Exercise, 22, 729-733.
#' The calculation is based on the following equation:
#' (equation)
#'
#' @examples
#' calculate_muscle_mass(
#'   180,
#'   sex = "male",
#'   fg = 24,
#'   cg = 34,
#'   c_skinfold = 100,
#'   tg = 55,
#'   t_skinfold = 100
#' )
#' @rdname calculate_muscle_mass
#' @export
calculate_muscle_mass <-
  function(height,
             sex = "male",
             fg,
             cg,
             c_skinfold,
             tg,
             t_skinfold) {
    # topendsports.com/testing/tests/muscle-mass-calculation.htm
    check_sex(sex)
    if (sex == "male") {
      ccg <- cg - pi * (c_skinfold / 10)
      ctg <- tg - pi * (t_skinfold / 10)
      muscleMass <-
        height * (0.0553 * ctg^2 + 0.0987 * fg^2 + 0.0331 * ccg^2) - 2245
    } else {
      stop("This equation only works for males")
    }
    return(muscleMass / 1000)
  }