I'm very new to learning JavaScript, so I've used an if/else to categorise some data, but the amount of data is huge.
It's part of a VO2 Max calculator that works out a persons VO2max and then decides if that value is Excellent, down to poor.
The data tables which the values are pulled from might be a way to go? But I don't know how:

How could I simplify this? What can I read to figure it out? Or is it not bad practice to use the below? Thanks.
if(vitals.gender === 1) {
if(vitals.age >= 18 && vitals.age <= 25) {
if(vo2 > 60) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 52) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 47) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 42) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 37) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 30) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 26 && vitals.age <= 35) {
if(vo2 > 56) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 49) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 43) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 40) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 35) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 30) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 36 && vitals.age <= 45) {
if(vo2 > 51) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 43) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 39) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 35) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 31) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 26) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 46 && vitals.age <= 55) {
if(vo2 > 45) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 39) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 36) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 32) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 29) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 25) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 56 && vitals.age <= 65) {
if(vo2 > 41) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 36) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 32) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 30) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 26) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 22) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 65) {
if(vo2 > 37) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 33) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 29) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 26) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 22) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 20) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else {
VO2MaxRating = "Missing";
document.getElementById("outputVo2").textContent = 'Either you\re under 18 or missing details';
}
} else {
if(vitals.age >= 18 && vitals.age <= 25) {
if(vo2 > 56) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 47) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 42) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 38) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 33) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 28) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 26 && vitals.age <= 35) {
if(vo2 > 52) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 45) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 39) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 35) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 31) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 26) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 36 && vitals.age <= 45) {
if(vo2 > 45) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 38) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 34) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 31) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 27) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 22) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 46 && vitals.age <= 55) {
if(vo2 > 40) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 34) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 31) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 28) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 25) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 20) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 56 && vitals.age <= 65) {
if(vo2 > 37) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 32) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 28) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 25) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 22) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 18) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else if (vitals.age >= 65) {
if(vo2 > 32) {
VO2MaxRating = "Excellent";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 28) {
VO2MaxRating = "Good";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 25) {
VO2MaxRating = "Above Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 22) {
VO2MaxRating = "Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 19) {
VO2MaxRating = "Below Average";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else if (vo2 >= 17) {
VO2MaxRating = "Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
} else {
VO2MaxRating = "Very Poor";
document.getElementById("outputVo2").textContent = vo2 + ' ml/kg/min (' + VO2MaxRating + ")";
}
} else {
VO2MaxRating =
document.getElementById("outputVo2").textContent = 'Either you\re under 18 or missing details';
}
}
if...elsestatements, make an array and pushtrueorfalsefor each category. Then you bitwise mask the array elements and shift them into 1 integer. Then you do bitwise masking and use aswitch...case(or multiples of them) to determine which best suits you. It may be complicated at first, but it's flexible enough.