Training Load Explained: Why Workout Minutes Are Not Enough

Training load describes the demands of exercise. Heart-rate-based methods combine duration with an indicator of intensity, rather than counting every minute equally. They estimate one aspect of internal load, not every physical demand of a workout. Training-load methods

Minutes still matter. But “I trained for half an hour” does not tell you whether that session was an easy walk, a steady ride or a demanding circuit.

Clarify's Effort model is designed to summarize recorded cardiovascular effort. It is not a score for how worthwhile your workout was.

Start with heart-rate reserve

Heart-rate reserve is the difference between your maximum and resting heart rates. Expressing exercise heart rate as a share of that reserve uses both reference values. Heart-rate-reserve ratio

Here, HR is your recorded exercise heart rate, HRrest is your resting heart rate and HRmax is your maximum heart-rate value.

The resulting percentage depends on those inputs. Including resting heart rate does not make an estimated maximum exact, or turn fixed zone boundaries into individually measured metabolic thresholds.

Weight time by intensity

Classic Edwards TRIMP adds time spent in five percentage-of-maximum-heart-rate zones, using weights of 1 through 5. Clarify's specified model instead uses percentage of heart-rate reserve, so it is an Edwards-inspired adaptation—not the original method. Edwards TRIMP definition

The specified Clarify bands are:

At the level of the calculation, weighted load is time in each band multiplied by its weight, then added together. The weights rise linearly, not exponentially.

A greater weight means a larger contribution to this model. It does not mean five times the fitness benefit, muscle damage or recovery requirement.

These bands are calculation categories, not a recommendation to train at a particular intensity. Activity below the first band can still be worth doing; a score is not a complete measure of an activity's value.

A display scale is not physiology

After accumulation, the specified Effort model applies a logarithmic transformation to make large load values easier to display. This makes equal additions of load produce progressively smaller increases on the displayed scale.

That is a mathematical presentation choice. It does not demonstrate diminishing training benefits, and logarithmic compression alone does not impose a maximum score.

For meaningful comparisons, the underlying time units and calculation method must stay consistent. Seconds and minutes cannot be substituted without changing the result.

What heart rate leaves out

Heart-rate-based load does not fully describe muscular demand. In a small study of functional fitness, perceived-exertion scoring distinguished session demands better than Edwards TRIMP. That finding illustrates a limitation, rather than proving one method is best for every sport. Functional-fitness study

For strength sessions, keep track of exercises, sets, repetitions and load as well as how the session felt. For other activities, add context relevant to your goals instead of expecting one cardiovascular score to explain everything.

Use Effort as context

Consider Effort alongside your training plan, recent workload and subjective experience. Heart-rate information is useful, but it cannot establish total readiness or safe training capacity on its own. Monitoring limitations

You do not need to chase a higher score. The useful question is whether the session served its purpose.

General fitness education, not an individualized training prescription or medical clearance.