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Of the various components that comprise a client’s total physical fitness program, cardiorespiratory endurance is probably the most misunderstood and underrated. In order to understand how to perform cardiorespiratory training in the most effective and efficient way, clients must first understand how such training in undertaken.
Many people incorrectly assume that cardiorespiratory training is synonymous with aerobic training; such as jogging or cycling at a moderate pace for extended periods of time. This misunderstanding can delay or even prevent individuals from achieving attainable fitness-related or sport-specific goals.
 The most common goals of performing cardiorespiratory training are the following.
  • To improve performance. A primary purpose of training is to delay the onset of fatigue during competition; no matter if it’s a pick-up game of basketball, 10k race, or completing a marathon.
  • To reduce mental anxiety. With fatigue comes a loss of concentration and confidence, critical components to performance.
  • Weight management. Proper cardio can help with the goal of weight loss and weight maintenance.


If the goal is to help clients improve stamina and muscular endurance, then overloading is necessary. The body must be presented with a workload that challenges its current fitness state. This increased workload will cause fatigue and, with the proper recovery, will eventually yield cardiorespiratory improvements.
If the workloads are of the right magnitude (i.e., slightly more than the body’s current capabilities), then the body must adapt to be prepared for the next time such a demand is placed on the body.
With this in mind, it is easy to understand that cardiorespiratory training is much more than jogging at a moderate pace for extended periods of time. To meet these goals, both the aerobic and the anaerobic energy systems must be trained.
This is especially true for fitness enthusiasts and athletes who must tap into top-end anaerobic energy systems to maximize performance, (such as soccer players late in a match or completing the last 100 yards of a 5K race). According to the principle of specificity, this would be impossible if only the aerobic energy system was trained.
There are many viable methods for introducing overload into a client’s training program to improve cardiorespiratory fitness such as Fartlek training, Tabata, circuit training, speed training, and HIIT Workouts.
No matter which method is used, the fitness professional should always keep the client’s physical capabilities in mind to ensure safety of the program. For the sake of this article we will discuss cardiorespiratory training using a three-stage model.
Stage I
Clients new to cardiorespiratory exercise need to develop a baseline level of aerobic fitness to avoid overtraining and exhaustion. Generally, exercising at an estimated maximal heart rate (HRmax) of 65 to 75% is a safe intensity for apparently healthy adults; or 12 to 13 on the Rating of Perceived Exertion Scale (RPE) 6-20 scale.
If using the talk test method to measure intensity, clients should exercise at intensities no higher than the level at which they perceive continuous talking for 10-20 seconds to first become “challenging.”
Clients should start slowly and gradually work up to 30 to 60 minutes of continuous aerobic exercise. During this training period clients should strive to gradually increase the duration and intensity of exercise bouts. Clients who can maintain a stage I intensity for at least 30 minutes two to three times per week will be ready for more intense cardiorespiratory exercise such as interval training.
Stage II
Stage II is designed for clients with low-to-moderate cardiorespiratory fitness levels who are ready to begin training at higher intensity levels. Stage II is the introduction to interval training in which intensities are varied throughout the workout. Clients training in stage II should use intervals ranging from 65 to 85% of HRmax; or 14 to 16 RPE. A more feasible option is to use the talk test where intensities range between the point at which continuous talking is “challenging” to the point at which it first becomes “difficult.”
Stage II differs from high-intensity anaerobic interval training in that it uses more moderate to challenging work intervals (i.e., running, not sprinting) with varying lower-intensity recovery periods (i.e. light jogging). This format also tends to be more engaging and less boring than steady state aerobic exercise.
As a general rule, intervals should start out relatively brief with a work-to-rest (hard-to-easy) ratio of 1:3 (i.e., 1-minute interval followed by a 3-minute recovery). Once fitness and overall conditioning improves, cardiorespiratory programs can be progressed using 1:2 and eventually 1:1 work-to-rest ratios. Moreover, the duration of each of these intervals can be gradually increased in regular implements.
Stage III
This stage is for the client who has a moderately high cardiorespiratory fitness level base. Stage III is a form of high-intensity interval training involving short, intense bouts of exercise (i.e. sprinting), interspersed with active bouts of recovery (i.e., light jogging). Clients training in stage III should use intervals ranging from 65 to 95% of HRmax; or 17 to 19 RPE. Using the talk test during this stage is also a viable option and represents intensities where any form of talking is “difficult to impossible.”
Recent research has clearly demonstrated the physiological benefits of high-intensity interval training (1, 2). However, because fatigue is inevitable, fitness professionals should recognize the need to adequately prepare the body for stage III first, emphasizing quality of training over quantity.
Fitness professionals should take the necessary time to build cardiorespiratory efficiency through stage I and II training before progressing clients to stage III training. The time needed to transition to stage III training is variable, perhaps requiring 2 to 3 months or longer, but clients should always earn the right to progress to this stage, rather than simply moving forward on account of a calendar date.
For an additional resource on this subject, check out Exploring Excess Post Exercise Oxygen Consumption.
Fitness professionals and weight loss trainers should communicate the need to gradually introduce overload into their client’s cardiorespiratory training programs to induce positive physiological adaptations.
Performing steady state aerobic exercise is necessary to build a solid cardiorespiratory base, especially for deconditioned clients; however, gradually increasing the intensity and duration of each exercise bout will help eliminate unwanted fitness plateaus and boredom.
Using a progressive approach such as the three-stage cardio training model will help clients achieve optimal levels of stamina necessary to achieve their fitness and sport-specific training goals in a safe and efficient fashion.
1. Wisløff U, Ellingsen Ø, Kemi O J. High-intensity interval training to maximize cardiac benefits of exercise training? Exercise Sport Science Review, 2009;37 (3), 139-46.
2. Daussin FN, et al. Effect of interval versus continuous training on cardiorespiratory and mitochondrial functions: relationship to aerobic performance improvements in sedentary subjects. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. 2008;295, R264-72.


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