function showValues(age) {
if (age == null || age == "") {
	alert("Please enter your age");
	return false;
}
hrm = Math.round(220 - age);
fb = Math.round(hrm*0.65);
card = Math.round(hrm*0.80);
document.getElementById("hrmax").innerHTML = hrm;
document.getElementById("fatBurn").innerHTML = fb;
document.getElementById("cardio").innerHTML = card;
}