Training load is a number for how much strain your training puts on your body. It combines how long you trained with how hard. A short, fast session and a long, easy one can carry the same load.
Why it matters
One workout says very little. What matters is how your recent training compares with what your body is used to. Ramp up too fast and you end up tired, flat or hurt. Do too little for too long and fitness fades. Training load turns that comparison into something you can see.
How Kiiro measures it
Every workout gets a training load from your heart rate: the time you spent at each intensity, weighted so hard minutes count more than easy ones, relative to your own resting and maximum heart rate. Any workout in Apple Health with heart-rate data counts, not only runs.
Kiiro then looks at your load in three ways:
- Acute load: your recent training effort, mostly from the past week.
- Fitness level: your longer-term training, roughly the past six weeks.
- Load balance and status: how the two compare, shown as a percentage and a status such as Balanced.
See training load in Kiiro for the status table and the full calculation.
You may know it as TRIMP
If you have used other training tools you may have seen a workout’s load called TRIMP, short for training impulse. It is the method Kiiro’s training load is built on, developed by the physiologist Eric Banister:
- Take the minutes you trained.
- Work out how far your heart rate sat between your resting and your maximum heart rate. This is your heart-rate reserve: 0% at rest, 100% at maximum.
- Weight it so that hard minutes count much more than easy ones. The weighting rises exponentially with intensity, because the strain on your body does too. The constants differ slightly for men and women.
An easy hour and a hard half hour can end up with a similar load. That is the point: it puts very different workouts on one scale.
Other tools use variants. Edwards’ version, for example, multiplies the time spent in each of five heart-rate zones by 1 to 5. They answer the same question, but numbers from one method cannot be compared with numbers from another, so your load in Kiiro will not match the number in a different app.
Related terms
- Acute load: Acute load reflects your recent training effort, mostly from the past week. It tracks short-term fatigue.
- Fitness level: Fitness level looks at your longer-term training, roughly the past six weeks. It represents your training base.
- Load balance and status: Load balance compares your current training load with your long-term fitness. Your status, from Undertrained to Overtrained, is the one-word version of it.
