Before you call it overtraining, rule these out

Six weeks of good training, then everything goes flat. Easy pace costs ten beats more than it should. You sleep badly, you are short with people, and the session you did comfortably last month now feels like a race.

The word that comes to mind is overtraining. It is the right instinct and usually the wrong label, and the difference matters because the three things it could be have three different answers.

Three things, one word

The consensus statement from the European College of Sport Science and the American College of Sports Medicine separates them carefully.

• Functional overreaching. A short-term drop in performance without severe psychological symptoms or lasting negative effects, which turns into an improvement in performance once you recover. This is what a hard training block is supposed to do.
• Non-functional overreaching. What happens when the balance between training and recovery is not respected. The performance decrement lasts longer and the improvement does not arrive on schedule.
• Overtraining syndrome. The consensus describes the keyword as prolonged maladaptation, not only of the athlete but of several biological, neurochemical and hormonal regulation mechanisms¹.

Almost every runner who says they are overtrained is somewhere in the first two.

Nobody can test you for it

Runners often assume a blood panel or a wearable metric will settle this.

The 2013 consensus reached the same conclusion from the other end: several markers are in use, and none of them meet all the criteria needed for their use to be generally accepted¹.

How thin the evidence actually is

This is the part that surprises people, including clinicians.

The list to work through first

The consensus is explicit that understanding the cause involves excluding organic disease and infection, and factors such as dietary caloric restriction, insufficient carbohydrate or protein intake, iron deficiency, magnesium deficiency and allergies¹. Every one of those produces the same picture, and every one has a different fix.

Two deserve extra attention in runners.

Energy. The IOC consensus on Relative Energy Deficiency in Sport describes a syndrome of health and performance problems in female and male athletes whose intake is too low relative to what their training costs⁴. Fatigue, poor performance, mood changes and repeated illness sit on both lists. A runner who has quietly been eating less while training more has a nutrition problem wearing an overtraining costume.

Sleep. It rarely appears on the symptom lists as a cause, only as a symptom. Yet sleep problems are associated prospectively with developing chronic musculoskeletal pain, with an odds ratio of 1.64 in the short term across 16 studies and 116,746 participants⁵. That is about pain rather than performance, so it does not transfer directly, but it is one more reason to fix sleep before concluding anything else.

What to do about the fortnight in front of you

Probably overreachingWorth escalating

After 10 to 14 easy days

Probably overreachingEasy runs feel easy again, and the first session lands.

Worth escalatingNothing has changed, or you feel worse.

Mood

Probably overreachingLifts along with the legs.

Worth escalatingFlat, irritable or low regardless of training.

Outside running

Probably overreachingWork and life feel normal.

Worth escalatingThe fatigue shows up everywhere, not just on runs.

Illness

Probably overreachingNothing unusual.

Worth escalatingRepeated minor infections over months.

Weight and appetite

Probably overreachingStable.

Worth escalatingUnintentional loss, or appetite that has disappeared.

The two weeks are not a diagnostic test, and a fortnight is short if you have been digging the hole for a season. But they cost you almost nothing in fitness and they sort most runners into the right group.

When to get properly assessed

The last two are the ones runners most often leave out of the conversation, and they are among the most useful.