From the early training days of Arthur Lydiard, runners have used miles to log their volume of workouts for a week. How many miles per week you ran were like badges of honor worn on your chest.

Some cyclists look at the distance of the Tour de France, over 2,000 miles in three weeks of racing, and compare their training to these distances – while others boast of century rides.

Now there is a new shift in the thinking of training, especially in terms of volume. Though distance was the standard way of measuring volume in the past, many eventually began to wonder if there was a better way to accurately assess the stress on the body.

Volume itself is defined as a measure of the frequency of workouts times the duration of those workouts. Notice in that definition there is no mention of the distance of workouts.

Why is distance not such a great marker for volume anymore? This is because too many factors can greatly affect the variance of training stress on the body, for the same workout done in different places. For example, a 10-mile run along the ocean versus a mountainous up-and-down run at altitude. Two 10-mile runs, each with very different training stress on the body. The same can be said for a bike ride, especially in windy conditions, or if participating in a group ride, where you can get pulled along by a pack of riders and perhaps coast a good distance. A solo ride of 100 miles straight into a strong headwind is not the same as a group ride on a non-windy day, even over the same course.

Take a couple of two-mile swims: one done in a pool, and one done in rough water with tough currents. The difference in the amount of stress on the body is almost immeasurable. But if your goal is a one-hour swim, what you lack in terms of distance in the open water is made up for in terms of the intensity of the swim, due to the currents. You would have no current in the pool, but you would likely swim farther, creating a very similar training stress to the one-hour swim in open water. Either way, the training stress is that of a “one-hour swim” on the body.

The key term here is training stress. The entire principle and point of training is to impose a given amount of stress or load on the body, allow adequate time for it to recover, and then repeat the cycle. As you gain fitness, the amount of training stress you can withstand should increase over time. If it's not increasing, you are likely not gaining any fitness.

The more detailed you can be in determining the level of training stress you experience with each workout, the better you can properly recognize the length of the recovery period you require. Some people give themselves too much time between sessions, and never take advantage of the fitness gains they get from a session. This is common among those who lack variance of intensity in their training, or are inconsistent with their training in general.

Many others make the mistake of timing this recovery period too short, and begin to drive themselves into an over-training downward spiral. This is common among those who do not plan out their training, just going from one hard workout session to another, often participating in group workouts.

When training stress is properly measured, and the recovery periods which you require are better known, the quality of training is maximized by simply not wasting valuable training time – and allowing yourself to receive maximum benefits following each training session.

Measuring time as a training stress metric, rather than using distance alone, will result in more accurate stress measurement and better quality training. Better quality training will lead to improved performance.

Does this mean distance isn’t a useful gauge? Not necessarily. Certainly in a pool workout where intervals are frequently done, it is hard to fully assess the amount of time you spend resting on the wall, awaiting instructions. The pool is a common area where you can use distance to help you understand the training stress of a given session, but it is most effective when combined with an understanding of the length of the session.

Distance is a great supplemental metric for measuring the training stress of your session, when looking at a timed session. By itself it can’t tell you intensity of a workout, but over a longer period of time, when compared to other sessions in a similar environment (the pool, a favorite local run or cycling route), it can begin to help you understand the training stresses you put your body through and how you respond to them.

If you can begin to look at the time your body spends under stress, rather than just the distance it covers, you should be able to more accurately assess your training stress for each session, and maximize your training with better balance of intensity and recovery.

Maximize your training by logging time for your workouts, not just distance. When you can see the training stress more clearly, you’ll be able to maximize your performances. And that is what it’s all about!

Jim Vance is a USAT Level 2 Certified Coach for TrainingBible Coaching (www.trainingbible.com) and a professional triathlete. Questions or comments can be sent to jvance@trainingbible.com.