Is there a relatively easy way to get better values for my heart rate zones if I already have a heart rate monitor?
A couple workouts I've done have my heart rate in the "hard" zone for 90-95% of the time, and practically none in the "light" or "medium" zones. My maximum heart rate so far is 193 and estimated resting heart rate between 55-65.
Basically, 50% is the transition point between resting and the first zone and every next zone is a 10% increase. Your max is 90%+.
Here's the chart:
Note: Image is from the wikimedia commons and released under CC-SA
But look at the charts as an approximate baseline average for most people they also don't paint a very realistic picture. Your VO2 MAX will actually increase if you do workouts that extend your anaerobic threshold. The harder you push toward your maximum, the higher your maximum raises so you'll be able to do even more intense workouts as it increases with less soreness/recovery time needed in between. Also, your resting heart rate will lower because of a healthier circulatory system (from your numbers it sounds like you're doing pretty good).
For the Weight control zone (which IMHO is the worst zone to work out if you're trying to lose fat) think of light exercise. Exercise you'll likely break a sweat from (unless it's cold/windy) but it doesn't really get you breathing hard (like a brisk walk). The type that you will cool down immediately after you stop.
In the aerobic range, your body starts to require more oxygen (for metabolism) so you start to breathe harder. I like to think of this as the point where you transition from normal resting breathing patterns to a point where you need to start focusing on more controlled breathing (I may be wrong about this though). If you stop after working out into your aerobic zone, it will actually take hours for your body to cool down completely (I'm more sure that this point is more accurate). You can see this effect by your heart rate being elevated above normal well after your workout.
Before I talk about anaerobic I want to make one thing clear first, when you transition into the anaerobic range your body doesn't just magically turn off its oxygen-based metabolism and switch over to oxygen-deprived metabolism.
The anaerobic range is just the range where your body is working at a sufficient intensity where it can no longer break down lactate fast enough; so it starts accumulating in your bloodstream. If you had a lab, you could test your blood as you work out to see this effect but that isn't very convenient so I use another technique to gauge.
The way I gauge it is, hop on a treadmill and slowly increase the speed and continually monitor your heart rate. When you're in the aerobic range (and you're warmed up) you'll start to settle into a 'zone' where it feels like you can just keep on going and going and going (because you can). This is because your body is efficiently using its energy stores. As you increase the speed slowly, you'll eventually hit a speed where the running feels like it's getting hard. Like you'll eventually start to wear down and have to focus your willpower to keep going.
I don't really see much point in working out in the lower zones unless you're away from your regular workout environment and want to get in some maintenance. If your goal is to increase endurance for a specific sport (like a marathon) targeting the aerobic zone is probably a good idea. If you're trying to lose weight and you're already fit enough to be comfortable with pushing well into your anaerobic zone (which it sounds like you are), then anaerobic workouts will probably be more effective for you. For the reasons see this or more specifically, the Wikipedia article on EPOC (Excess Post-Exercise Oxygen Consumption.
From the article:
Studies show that the EPOC effect exists after both anaerobic exercise and aerobic exercise. Such comparisons are problematic, however, in that it is difficult to equalize and subsequently compare workloads between the two types of exercise. For exercise regimens of comparable duration and intensity, aerobic exercise burns more calories during the exercise itself,[6] but the difference is partly offset by the higher increase in caloric expenditure that occurs during the EPOC phase after anaerobic exercise. Anaerobic exercise in the form of high-intensity interval training was also found in one study to result in greater loss of subcutaneous fat, even though the subjects expended fewer than half as many calories during exercise.[7] Whether this result was caused by the EPOC effect has not been established, and the caloric content of the participants' diet was not controlled during this particular study period.
To summarize, with both aerobic and anaerobic exercise, your body's metabolism increases and burns more energy well after your workout. Even though aerobic burns more during exercise, the amount is offset by the higher increase in metabolism after anaerobic exercise.
The EPOC effect clearly increases with the intensity of the exercise, and (at least in the case of aerobic exercise, perhaps also for anaerobic) the duration of the exercise.
Studies comparing intermittent and continuous exercise consistently show a greater EPOC response for higher intensity, intermittent exercise.
Basically, higher intensity is better.
A heart rate monitor is a great tool to have. Once you get a feel for where the different zones for you, it should be easy to target whatever specific zone you're trying to hit and monitor how your body is adjusting as you improve.
Sounds like you are training for something big (like a marathon?). I would suggest getting a heart rate monitor that allows you to get the graph of the data like the Garmin Forerunner 405. It's super easy to track your progress with a gadget with GPS capabality especially if you are doing cardio (i.e. running, cycling), you can see how your heart rate improves on hills.
Your heart rate values will naturally improve as your muscles become more efficient from your training. The workouts eventually get easier on your heart as it gets trained. Not sure what your goal is (i.e. time? distance?) but training your body to get used to say running 20 miles a day will make one 5K race a cinch! So you can train for something bigger if you want to be more efficient in something shorter.
