Aerobic fitness can be defined as the body’s ability to use oxygen, or the functional capacity of the cardiorespiratory system, during physical activity. Improving aerobic fitness can be achieved by increasing the aerobic capacity—the maximum amount of oxygen the body can use over an extended period of time. Training programs designed to improve aerobic fitness incorporate different types of aerobic exercise with specific protocols for the program.
The most common types of aerobic fitness training programs include running, biking, swimming, rowing or a combination of two or more activities. Each type of activity can be split into different training programs based on the specific workout and intended benefit. Interval training, for example, is a mixture of work and rest over a specific period of time with the intention to improve aerobic capacity and fitness.
Workout intensity, including the workout duration and amount of work, is one of the key components to improving aerobic fitness. Training programs will outline the recommended intensity for each workout to achieve maximum results. Greg Glassman, founder of CrossFit, recommends following a three days on, one day off rotation to maintain maximum intensity during every workout. During each workout, the Time-to-Run.com website recommends exercising within a heart rate range to improve aerobic capacity. Calculate your maximum heart rate—based on age—and train at 70 percent maximum for moderate exercise.
The human body uses three metabolic pathways during exercise to provide energy to the working muscles. The glycolytic and phosphagen metabolic pathways are used for high-intensity anaerobic activities while the oxidative pathway is used for aerobic exercise. For improving aerobic fitness, training programs will focus primarily on low-power activities lasting more than several minutes. Glassman, however, recommends incorporating each pathway into the training program for maximum benefit.
According to the Sports Fitness Advisor website, there are three categories—respiratory, cardiovascular and musculoskeletal—of health benefits and adaptations for endurance and aerobic training. Respiratory adaptations include improved blood flow and oxygen exchange in the lungs with a decreased respiratory rate and pulmonary ventilation. Cardiovascular adaptations include increased cardiac output, blood volume, skeletal muscle blood flow and thermoregulation. Musculoskeletal adaptations include increased mitochondrial size and density, oxidative enzyme concentrations and myoglobin concentrations.
Recovery and nutrition play an important role in preventing overtraining and maximizing results. Training programs will have built-in rest and recovery days to allow the body and muscles to repair themselves. Recovery is a key to improving and is needed to prevent overtraining—also known as chronic fatigue. Nutrition supplies the body with the nutrients necessary for recovery along with the fuel needed during aerobic fitness training.