Your Cardio Load reads 260 and the chart says Building quickly. Last month it read 310 and said Steady. The higher number was the calmer one, and that is the whole idea: Cardio Load is not about how much you train, it is about how fast that amount is changing.
Two averages, not one
Every tracked workout earns load points from the minutes you spent in each heart-rate zone, with a minute in zone 5 worth five times a minute in zone 1. Sports science calls this a training impulse, and it is the same raw material Strain is built from.
NOYU then keeps two running averages of those points. The recent one leans on the last seven days, so this morning's session counts for more than last Monday's. The longer one leans on the last six weeks, and it is a fair picture of the training your body has adapted to.
The big number on the chart is the recent average. The label comes from dividing it by the longer one. Recent load between 80% and 130% of your six-week load reads Steady. Below that is Lighter than usual. Above it is Building quickly, and past 150% it becomes Much higher than usual.
Why a spike matters more than a high number
Your body adapts to what you ask of it regularly. Tendons, bones and the heart all build tolerance to a level of work, and that tolerance is what the six-week average represents.
A sudden jump above it asks for work you have not built tolerance for. A number of studies in team sports and running have found more injuries in the weeks after a large jump in load than after a similar load reached gradually. A high, stable number is the training you have earned. A sharp rise is a bet on tissue that has not caught up yet.
Later research has questioned how reliably the ratio predicts injury in any one person, so treat it as a clue rather than a forecast.
The first six weeks
NOYU can show your recent load after a week, but the comparison needs six weeks of history to mean anything. Until then the chart reads Calibrating rather than comparing you with an average that does not exist yet.
The same applies after a long break. Come back after a month off and your six-week average is close to zero, so an ordinary week reads as a huge jump. That is accurate. Your body has detrained, and the number is telling you to rebuild the average before you rebuild the volume.
What it cannot see
Cardio Load counts tracked workouts with heart-rate data and nothing else. Walking to work, a day on your feet and a strength session all lift your heart rate and none of them add load points unless you record them as a workout. Strain sees your whole day; Cardio Load sees your intentional cardio.
It also measures the cardiovascular side only. Running downhill and cycling at the same heart rate earn the same points and do very different things to your knees. Cardio Load cannot see an old injury, a change of shoes or a new surface. It knows your heart worked, not what your legs were doing.
What to do with it
Read it next to your Readiness and what you meant to do this week. A planned build to a race and an accidental spike draw the same shape on the chart, and only you know which one it is.
Building quickly during a deliberate block is the plan working. The same label when you did not plan anything is a reason to hold the level for a week rather than add to it. Lighter than usual after a hard block is recovery. The same label for a month is detraining. The chart shows the shape. You supply the reason.
