H'ok. We all remember the PE class schpiel about max heart rate (MHR) and target heart rate (THR). Turns out that sports science has advanced enough that there's a more detailed theory about what range we should be trying reach to achieve certain results.
And if you're a fatboy like me and have been punishing yourself on a treadmill wondering why you're not seeing any gains AT ALL, then you're probably doing what I'm doing: training like you were an 18 year old athlete instead of a 40ish computer nerd. Or to put it another way, pushing way too hard.
Here's what I've learned and how I'm planning on changing up my workouts to see if it makes a difference... more words after the jump.
Two Types of Exercise
Think back to high school biology and remember that there's two kinds of ways your body creates energy: aerobic (body uses oxygen to fuel activity) and anaerobic (body uses something else to fuel activity because oxygen supply isn't great enough to handle the needs). A good example of aerobic workouts would be a jog, whereas anaerobic would be a flat-out sprint.
Why is that important?
In aerobic mode (with oxygen), your body is pulling fuel from stored fat. It's also realizing that the cardiovascular system is being used, so the heart gets stronger, the lungs get better at trading CO2 for oxygen, and the circulatory system gets better at shuttling these gases around your body. This is where you want to be if you want to lose weight and "get in shape".
In anaerobic mode (without oxygen), your body is basically in an full-on afterburner situation. Since it can't bring in enough oxygen to handle the process of breaking down fat, it starts just burning up glycogen that's been stored in your muscles. Glycogen is the stuff that your muscles keep on hand to respond to anaerobic situations (ie: "OMG IT'S A LION! RUN!!") and comes from what you ate the day before. If it doesn't get used, it gets converted to fat and saved for a later day. If it does get used, it winds up as lactic acid and leaves the muscle sore.
So here's the trap: If you are like me (overweight), head into the gym and hit it too hard for an hour, you end up doing anaerobic work instead of aerobic. Not only do you not burn the fat you were trying to lose, but now your body is screaming for more food to replace the glycogen you burned up AND you've got sore (possibly injured) muscles. What's worse, that big after-workout meal you eat gets turned into glycogen, sits unused while you recover, and then gets converted to more fat! /o\
It's a strange thought: if you work out too hard, then the best you can do is not gain weight.
And it turns out: I've been working out too hard.
The Numbers to Know
Max Heart Rate
The first thing you need to know is your maximum heart rate - MHR. There's a couple of ways to calculate it, but I use: MHR = 207 - ( your_age * 0.7 )
Since I'm 38 (well, almost) it works out for me: MHR = 207 - ( 38 * 0.7 ) = 207 - 26.6 = 180.4
And there you go. If my pulse ever gets above 180, my heart will explode and I'll die instantly. ;) Ok, not really, but it seems like a great excuse to get out of doing hard work.
Using the MHR as your base, you can calculate the heart rate for other zones by simply taking a percentage:
The Red Zone - 90-100% - Improves speed (fast twitch muscle fibers), can only be done for short periods. Only very fit can reach this. Mostly used for interval training. This is what you shoot for if you're an Olympic 100m dash hopeful. For me, this would be a pulse rate of 162 - 180.
The Anaerobic Zone - 80-90% - Burns glycogen in the muscles more than fat, creates lactic acid. Emergency reserves. For me, this is a HR of 144 - 162.
The Aerobic Zone - 70-80% - Uses oxygen and fat for fuel, develops your cardiovascular system. As fitness improves, you'll find you have to work harder to get to this zone (ie, this is where you want to be if you want to shave time off your mile). For me, this is an HR of 126 - 144.
The Warmup/Recovery Zone 60-70% - Develops basic aerobic capacity and endurance, allows muscle to reenergize with glycogen. This is why it's a good idea to at least keep walking around in between sets or sprints and why coaches and personal trainers are always yelling at you to "KEEP MOVING!" instead of collapsing in a heap. For me, this is an HR of 108 - 126
When I went back to the gym for lifting, my routine started out with a 12 minute run on the treadmill before diving into 3x8 lifts that took around 45 mins to an hour to get through. I'd finish up with another 1/4 mile on the treadmill and maybe some jump rope work.
My big goal was to get a 12 minute mile. In order to get there, I kept pushing the speed up and up and up until I made it. Yeah, I was hurting, but I crossed the finish line. Unfortunately, I had trouble maintaining the time across subsequent weeks and even worse I wasn't getting any faster (nor losing any weight). My heart rate was pushing up into the low 150's in order to hit that target... both of those are numbers well inside the anaerobic range.
Since I was basically trying to maintain a sprint for 12 minutes (whups), I fell into the trap of trying to run it in intervals, which was even worse as the heart rate would spike up into the low 160's (red zone!!) during the 2 minute run phase and only drop to 135-140 during the 1 minute jog phase.
What I should have done was to disregard the distance and instead focus on doing longer runs at a lower heart rate: 30 minutes at 130-135 would have done a lot more for me than the interval stuff.
Acquiring a heart rate monitor seems like a good idea. I've currently got the Mio Sport on my birthday wishlist... it doesn't use a chest strap nor does it require you to stop and touch a finger to a sensor to get a reading. Yeah, it's not as accurate, but I'm looking for general hints rather than scientific precision.
Restructuring the workouts is also on the todo list. My current experiments have me turning in an hour of swimming and then another hour of shadow boxing or heavy bag work. I might need to back off on one and see if I can put the treadmill back into the equation at a slower speed but longer run.
For now, my new scale is based on the low-end numbers and goes something like:
108 - would rather be watching Dr. Who
126 - now we're talking... can already feel myself getting lighter
144 - OMG! LION!!!
162 - unless I'm sprinting in the Olympics, this is probably unneccessary
180 - heart exploded... seek medical attention at earliest convenience
Links to Info
And just so you guys don't think I'm totally making everything up:
Heart Rate Training and Calculator
Everything You Wanted to Know About Glycogen
Pick a Max Heart Rate Formula