8 Things to Know About Aerobic Capacity

Provided by American Council on Exercise

There are three components of exercise: resistance training, flexibility (actually, it’s more appropriate to call it “mobility,” but that’s a subject for another blog on another day) and cardiorespiratory training. Resistance-training exercises help improve both muscle strength, which can elevate resting metabolism (the number of calories burned while at rest), and functional performance in a variety of activities. Flexibility or mobility exercises can reduce muscle tension and improve joint range of motion, which are essential for enhancing overall movement efficiency. And finally, cardiorespiratory training improves the ability to both move oxygen and nutrients to working muscles and to remove metabolic waste, which allows muscles to continue to perform a particular activity. Every person starting a workout program will have a unique goal, but each goal requires a different level of focus on each of these components.

A well-designed exercise program includes all three components. However, if a client wants to improve definition and/or physical function, for example, you would focus his or her program on strength training. Likewise, if a client’s goals are to improve mobility and movement efficiency, you would focus on flexibility. And if your client is participating in a race or wants to lose weight, you would emphasize cardiorespiratory training. Cardiorespiratory training can enhance the body’s ability to metabolize fats and carbohydrates into fuel, both with and without oxygen. While cardio training is most often associated with fat loss, it is also the best way to improve aerobic capacity, which is the ability to use oxygen to fuel exercise activity.

During low- to moderate-intensity exercise, muscles rely on energy from a combination of oxygen and the substrates of carbohydrates (in the form of glycogen), and fats (called free fatty acids). The more oxygen that can be consumed, the more physical work an individual will be able to do. And, because the body burns about 5 calories of energy to consume 1 liter of oxygen, increasing aerobic capacity can help the body become more efficient at using oxygen. This, in turn, helps burn calories, which an important component of weight loss.

Regardless of what your clients’ fitness goals may be, improving aerobic capacity can help move them closer to reaching them. For strength-related goals, enhancing aerobic capacity can improve blood, oxygen and nutrient flow to working muscles and help with recovery between sets of resistance-training exercises. Improving the flow of blood to muscles can also help improve flexibility. For weight-loss or endurance-training goals, improving aerobic capacity is essential for achieving them.

Here are eight things to consider when structuring your clients’ programs to maximize the benefits of enhanced aerobic capacity:

During exercise, oxygen consumption can be measured one of two ways: (1) at maximal levels of exertion (during a medically supervised stress test) to identify maximal aerobic capacity or VO₂max, or (2) via absolute terms, the amount of oxygen consumed per minute of exercise. Each measurement is specific to your current level of fitness, but it’s important to understand that aerobic capacity is a relative measurement. This means that a larger person with more muscle mass will consume more oxygen at the same intensity than a smaller individual.
Increasing aerobic capacity can help improve the flow of oxygenated blood to muscle tissue, which, in turn, can improve mitochondrial density. Mitochondria are the organelles of a muscle cell that use oxygen to help produce adenosine triphosphate (ATP), which is the actual fuel that supplies muscle contractions. Improving mitochondrial density improves a muscle’s ability to use oxygen, while also improving the overall health and function of the cells.
High-intensity interval training (HIIT) is not only effective for burning calories, but it can also help improve aerobic capacity. At higher intensities, the body will use ATP from anaerobic sources, but will rely on aerobic metabolism during the lower-intensity recovery intervals to help replace the energy spent during the high-intensity work periods. The downside is that while HIIT is effective, too much of it could cause overtraining. For best results, limit your clients to no more than three HIIT workouts per week.
Low-intensity steady state (LISS) training, also known as long slow distance (LSD) training, is the ability to maintain a steady work-rate over an extended period of time. LISS relies on aerobic energy pathways for energy and can supply fuel muscle activity for extended durations like endurance races. Compared to HIIT, LISS is a lower-stress way to improve aerobic capacity, but it is not as effective for burning calories (for a specific comparison between HIIT and LISS, click here). The upside, however, is that LIIS can be performed almost every day, especially for those who can walk or ride a bike to work.
Cross training, popularized in the late 1980s by two-sport sensation Bo Jackson, refers to doing different activities or modes of exercise on different days to achieve a specific fitness goal. Performing a LISS run on one day followed by a HIIT cycling class followed by a circuit-training workout on the third day is an excellent example of how to periodize a workout to improve overall aerobic capacity.
Another approach is to do cross training in the same exercise session. For example, have the client perform 10 minutes of steady-state walking on an incline on a treadmill, 10 minutes of HIIT intervals (30 seconds at high intensity/30 seconds at low intensity) on a stationary bike, 10 minutes of steady-state training on a rowing ergometer, and finish up with 10 minutes of circuit resistance training. Breaking up a workout into short bouts of exercise on different pieces of equipment can help challenge the muscles to work differently on each piece of equipment. This, in turn, can help improve aerobic capacity while reducing the risk of overuse injuries from doing too much of the same exercise.
Dance classes, also referred to as hi-lo aerobics, are another great way to improve aerobic capacity while having fun. There is a reason why programs like Zumba are so popular—they help improve aerobic capacity, but in a format that resembles a fun party as opposed to a strenuous workout.
As discussed earlier, muscle is a metabolically active tissue, which means that it can use oxygen for fuel during exercise and at rest. A pound of muscle burns about 5 calories or so in a 24-hour period; therefore, adding 5 pounds of muscle can help improve resting metabolism by approximately 25 calories per day, which is the equivalent to walking a quarter mile (four hundred meters) without the effort. This is where strength training comes in to support cardio goals—adding muscles means the body can become a more effective oxygen-consuming machine.

Post Author AUTHOR

Pete McCall

Health and Fitness Expert

Pete McCall, MS, CSCS, is an ACE Certified Personal Trainer and long-time player in the fitness industry. He has been featured as an expert in the Washington Post, The New York Times, Los Angeles Times, Runner's World and Self. He holds a master's degree in exercise science and health promotion, and several advanced certifications and specializations with NSCA and NASM.