Overtraining Statistics: Symptoms, Recovery, & Prevalence

Overtraining syndrome appears to be extremely rare, and exact prevalence and incidence data are lacking

Review of the epidemiology. Studies use varied terms, and most research has been on athletes with overreaching rather than true overtraining syndrome.

One study found a lifetime prevalence of non-functional overreaching of about 60% in elite male and female runners, against 33% in non-elite female runners

Figures reported in the review's epidemiology section; they describe overreaching, not the much rarer full syndrome.

'Staleness' was reported in 5-30% of swimmers over a season and in 15% of British elite athletes

Survey estimates collected in the review; a multicountry survey found 35% of adolescent swimmers had been 'overtrained' at least once.

29% of 376 young English athletes reported having been non-functionally overreached or overtrained at least once

Athletes averaged 15 years old across 19 sports. Rates were higher in individual sports, low-physical-demand sports, girls and at elite level; training load itself was not a significant predictor.

Functional overreaching recovers in days to weeks, non-functional overreaching in weeks to months, and overtraining syndrome takes months, with a performance decrement lasting more than 2 months

Definitions from the review's table, based on the European College of Sport Science position. Functional overreaching ends in improved performance after rest.

No marker in current use (hormones, performance tests, psychological tests, biochemical or immune markers) meets all the criteria to be generally accepted for diagnosing overtraining syndrome

Telling non-functional overreaching from the syndrome depends on clinical outcome and on excluding other causes such as infection, calorie restriction, low carbohydrate or protein intake and iron deficiency.

Maximal heart rate appears to fall in almost all overreaching studies, while effects on submaximal heart rate are inconsistent

Review of heart-rate monitoring. Only a few studies had looked at heart rate variability after intensified training, and no firm conclusions could be drawn.

In elite endurance athletes, both increases and decreases in heart rate variability have been linked to negative adaptation

HRV can fall even as resting heart rate drops ('saturation'), so the authors recommend averaged, individual long-term baselines rather than single readings.

Functionally overreached triathletes slept 7.9% less during overload training, and 67% reported upper respiratory infections against 11% of controls

27 trained male triathletes; 9 of the 18 on a 3-week overload became functionally overreached. Sleep returned to normal during the following 2-week taper.

Across ten years of monitoring 400 competitive swimmers, mood disturbance rose in a dose-response manner with training load and fell to baseline when load was reduced

200 female and 200 male swimmers assessed every 2-4 weeks through the 1975-1986 seasons with mood-state questionnaires.

The Profile of Mood States identified 81% of 'stale' swimmers in two studies, and adjusting load in response to it cut burnout in collegiate swimmers from 10% to zero

Findings summarized in the review; mood questionnaires are among the cheapest and best-tested monitoring tools.

Of 94 elite junior soccer players monitored over two seasons, 7 showed a performance decrease lasting at least a month, with mood and hormone changes typical of non-functional overreaching

Those players scored higher on depression and anger and had lower resting growth hormone and post-exercise ACTH; the two hormones classified all but one player correctly.

In elite cricket fast bowlers, an acute:chronic workload ratio of 1.5 or more brought a 2-4 times greater injury risk over the next 7 days, against about 4% when acute load was at or below chronic load

Gabbett proposed 0.8-1.3 as the training 'sweet spot' and 1.5 or more as the 'danger zone', drawing on cricket, Australian football and rugby league data.

In Australian football, raising weekly training load by 15% or more lifted injury risk to 21-49%, against under 10% when load stayed between 5% below and 10% above the previous week

Data reviewed in the same paper; Gabbett recommends keeping weekly increases under 10%.

A 2020 analysis found no evidence supporting the acute:chronic workload ratio in training recommendations aimed at reducing injury

No study had estimated causal effects, and the ratio's statistical properties add noise and artifacts. Rapid load spikes still deserve caution; the specific ratio thresholds are contested.

A scoping review of 47 studies found minimal evidence that true overtraining syndrome has occurred in strength sports or resistance training

Short blocks of high-volume or high-intensity lifting can cause functional overreaching, and chronic high volume or intensity can lead to non-functional overreaching.