Training the endurance athlete presents a special situation for personal trainers: It’s likely that these athletes have already achieved an extremely high level of fitness before seeking out the services of a personal trainer.

With that in mind, the most common reason an endurance athlete seeks out the services of a trainer is to help him or her improve performance in a specific endurance event.

This means that the goal when working with such an individual is to maximize his or her ability to utilize oxygen (maximal oxygen uptake) while also maximizing the ability to perform at that maximum level for a longer period of time.

Such training not only stresses aerobic energy systems to their utmost, it also necessitates a major contribution from the anaerobic energy systems. It is important to keep in mind that special care must be taken to control any anaerobic contribution, however, as it can inhibit performance by shutting down muscle function with high levels of lactic acid just as easily as it can enhance performance by extending a person’s ability to perform at near-maximum levels for extended periods.

In order to make these performance improvements, it is important to note that it is not always necessary to train at maximal intensity to place sufficient stress on the aerobic and anaerobic systems for the purpose of increasing maximal oxygen uptake.

Research indicates that maximal oxygen uptake is reached at 80% of maximal performance speed for a given training distance which is also indicative of approximately 95% of the athlete’s maximum heart rate. Therefore, two simple calculations can be used to yield information sufficient to prescribe appropriate training intensities based on either time for a particular training distance or training heart rate.

Training Time for a Specific Distance

Client A can swim 200 meters in 120 seconds. In order to calculate the training interval that she will use for that distance, divide the time by 80% such that:

120 seconds/0.80=150 sec.

Training Heart Rate

Client B specializes in the one-mile run. For training purposes, he is performing repeated half-mile runs. During his best timed half-mile run, he exhibited a maximum heart rate of 200 beats per minute (BPM). So, to calculate this client’s training heart rate, simply multiply the maximum heart rate by 95% as follows:

200 BPM*0.95=190 BPM

Keep in mind that exercise at these intensities will improve maximal oxygen uptake while preventing an excessive contribution from the anaerobic energy sources.

The frequency and duration of exercise sessions should be adjusted according to intensity. The higher the level of exercise intensity, the less often training at that level can be performed. In other words, if Client B takes 3 days to recover from a 90% intensity workout, it might take just a day or two to recover from a workout at 75% intensity.


Adequate recovery time between higher-intensity training sessions can be gauged by observing a client’s ability to repeat and maintain training performance over a number of progressively more intense training sessions, mixed in with several less intense “recovery” workouts.

Such “recovery” workouts are made possible for two main reasons. One reason is that a well-trained aerobic athlete’s cardiorespiratory system recovers from exercise quickly and is rarely a determinate of one’s ability to recover from a training session. Another reason is that the lower intensity “recovery” workouts put less stress on the anaerobic systems since aerobic systems furnish the primary sources of energy at low levels of intensity.

While incomplete recovery of the anaerobic systems are generally responsible for overtraining and lagging performance, interspersing these low intensity “recovery” workouts will not significantly affect the anaerobic systems still recovering from the most recent high intensity workout (high intensity being responsible for depletion of the anaerobic systems). For these reasons, the aerobic systems, utilizing oxidized carbohydrate, fatty acids, and slow twitch muscle fibers, can be trained more frequently by the already conditioned athlete in order to maximize aerobic capacity development.


These resources are for the purpose of personal trainer growth and development through Continuing Education which advances the knowledge of fitness professionals. This article is written for NFPT Certified Personal Trainers to receive Continuing Education Credit (CEC). Please contact NFPT at 800.729.6378 or with questions or for more information.