In our past two columns we focused on different types of muscular strength and short-term endurance training. Although there’s plenty more to address on those topics let’s shift the focus to long-term endurance also called aerobic fitness.
There are several important facets of aerobic training to keep in mind when designing your workout. You must understand the basic principles of aerobic fitness how to measure your aerobic capacity and the mechanics of improvement. Knowing and understanding these factors even at a basic level lends structure to the program-design process and makes aerobic training more interesting and less tedious. In this month’s column we’ll discuss the basic principles of aerobic fitness and how to measure it. Next month we’ll address the mechanics of improving your aerobic fitness.
Basic Principles & Workouts
It’s easy to understand why so many people avoid aerobic training. If you’re not in shape it can be pretty uncomfortable if not downright painful to get up and get moving. On the other hand some people try to do too much too soon when starting a new fitness routine sometimes resulting in injury. That is why we stress starting slowly if you haven’t been participating in a regular physical fitness program.
So what does it take to become more aerobically fit? One of the best actions you can take to start your aerobic training is to turn off the TV! The TV is like a time vortex. Keep track of the number of hours you spend a week watching TV. Can you honestly say you don’t have an extra two hours a week to exercise?
Next find exercise you enjoy. If running is too difficult for you pick something that isn’t quite so high impact. You can use aerobic training machines if they’re available but there’s nothing wrong with dusting off your bike or taking a brisk walk around the neighborhood in the evening.
The three key elements to a successful aerobic training program are rhythmic activity the use of large muscle groups and a sustained effort. Rhythmic activity is a repetitive muscle effort during training. Large muscle groups include leg muscles (running walking stepping or cycling) chest muscles (swimming or arm ergometer) or back legs and arm muscles (rowing). Sustained effort means you continue the activity or exercise for at least 20 minutes at a moderately high heart rate.
Just because some activity makes you breathe hard and increases your heart rate does not qualify it as an aerobic workout. For example super-setting a weightlifting workout will raise your heart rate; however this is not an aerobic workout because the increased heart rate is caused by constricted blood vessels and erratic breathing not by oxygen demand (we’ll discuss oxygen demand in the next section).
A great aerobic exercise for firefighters is climbing stairs. It is an excellent way to strengthen your legs while training aerobically for a common fireground activity. Try climbing stairs in running shoes and gym clothes at first then work your way up to wearing turnouts or a weight vest.
Another good training exercise for firefighters is rowing. Rowing uses nearly all your muscles and provides a great overall aerobic training opportunity. It is also very low impact making it a safe activity for people with joint issues.
Measuring Aerobic Fitness
Now that we’ve addressed some basic aerobic activities let’s focus on how to measure your level of aerobic fitness. One way to do this is to test your VO2max (derivation: V – volume per time O2 – oxygen max – maximum) which is defined as the highest rate at which your body can take in and utilize oxygen. It is measured by the amount of oxygen used (in milliliters) per kilogram of body weight per minute (mlO2/kg/min). Just as you hear firefighters talk (or brag) about the maximum amount of weight they can bench press you hear distance runners and cyclists talk about their VO2max scores.
VO2max is a way to measure your ability to generate the energy necessary for endurance activities like running for more than four to five minutes. One of the most common methods to measure VO2max is the treadmill test during which intensity speed and incline are incrementally increased until you reach exhaustion. Oxygen consumption is measured by evaluating the O2 quantity of both inhaled and exhaled air and the respiratory rate.
Two common simple and inexpensive ways to test VO2max are the 1.5-mile run and the 12-minute run. Both involve running as fast as you can for the prescribed distance or time. You can find charts and graphs on the Internet to determine your VO2max scores based on your time.
To give you an idea of some VO2max values the average non-active male scores about 35 mlO2/kg/min while elite endurance athletes score about 70 mlO2/kg/min. Firefighters should have a VO2max of 45 mlO2/kg/min or greater. Although your sedentary VO2max score is genetically predetermined you can greatly improve your aerobic fitness score with the right endurance training. But how do you do this?
Aerobic vs. Anaerobic Systems
Your body has two systems that generate energy for activity the aerobic system and the anaerobic system. Several factors determine which system (or combination of systems) you will use: intensity duration fitness level and fuel availability.
Aerobic exercise means your body is using oxygen to sustain the desired level of exertion. Anaerobic activity means your muscles are producing energy without oxygen. The point at which most of the energy for activity shifts from being produced by the aerobic system to being produced by the anaerobic system is called the anaerobic threshold (AT). Once you cross the AT your effort is more labored in order to maintain that level of exertion.
When the demand is high and the aerobic system cannot provide sufficient energy output your anaerobic system kicks in to make up the difference. Not only is the anaerobic system less efficient than the aerobic system it also results in lactic acid development (i.e. the “burn” you feel) which eventually leads to muscle fatigue and failure.
It is also interesting to note that in the first several minutes of aerobic activity your body uses the anaerobic system for energy. Why? Because the aerobic system requires body heat and metabolic enzymes to get up and moving and that takes a few minutes to occur. This explains why the first 4—8 minutes of your aerobic workout can feel so labored.
The point at which the aerobic system takes over the majority of energy production is often called the “second wind.” Until the body gets warmed up and this “second wind” kicks in even fit athletes feel the inefficiency of the anaerobic system. One benefit of being more fit: The aerobic system kicks in sooner than it does in people who are less fit. This fact is particularly significant on the fireground. We rarely have the luxury of warming up prior to intense exertion. The more physically fit you are the faster you’ll reach the “second wind.” If you’re not in good physical condition you may never settle into an aerobic effort. If the level of exertion is high enough you may go straight from the anaerobic warm up to working above your AT which is no fun at all.
Get Out & Move!
We work in an industry that requires us to be physically fit not just strong. As such we must make aerobic training a priority. Whether you run walk or bike the key is to find an activity you’ll actually enjoy. The benefits are endless but the bottom line is this: When you improve your aerobic fitness you increase your efficiency on the fireground as well as your general health. So get out and get moving!
