Overtraining syndrome (OTS) is a difficult condition to identify and treat in high level athletes. In this case report, we describe a unique presentation of overtraining syndrome in a 20 year old high level long distance runner who developed exercise intolerance in the form of presyncopal like episodes during competitive racing. After thorough evaluation to rule out other causes for symptoms, the diagnosis of exercise swoon in the setting of OTS was made. The athlete was appropriately managed with a prolonged break from sport and gradual reintegration and monitoring of performance and training thereafter.

Overtraining syndrome , Exercise swoon , Syncope , Autonomic dysfunction

OTS: Overtraining Syndrome; PFT: Pulmonary Function Testing; ECG: Electrocardiogram; VO2max: Maximal Oxygen Uptake.

Moore BJ, Allison TG (2020) Exercise Intolerance in a High Level Collegiate Female Runner. Ann Sports Med Res 7(1): 1140.

Overtraining syndrome (OTS) is a complex condition that occurs in athletes when training loads consistently exceed recovery capacity [1,2]. OTS can present as abnormalities in multiple domains, including the autonomic nervous system, endocrine system, and psychiatric system [1,2]. This case details a unique presentation of exercise intolerance in a high level runner eventually diagnosed as exercise swoon related to underlying OTS.

The patient is a 20 year old high level collegiate long distance runner who presented for cardiac stress testing related to a one year history of exercise intolerance. Her symptoms began at the end of her college freshman year, a year in which she had broken many school and division records for cross country and track. Symptoms began shortly after she experienced a one-time episode consistent with benign exertional collapse, where she developed a presyncopal episode after finishing an intense race on an exceptionally hot day. Over the following several months, however, she developed presyncopal events midway to near the end of her races during competition running events. During these episodes she would develop a progressive lightheaded sensation that forced her to stop running and slowly lower herself to the ground. She denied any complete loss of consciousness, loss of bowel or bladder, injury to self, heart palpitations, or shortness of breath. These episodes did not occur during training or practice runs. Around this same timeframe she developed gastrointestinal issues which were diagnosed as reflux, hair loss, fatigue, poor sleep, and amenorrhea. Thorough workup including normal complete blood count, electrolyte panel, iron panel, thyroid labs, cortisol labs, sex hormone labs, progesterone withdrawal test, pelvis ultrasound, abdominal ultrasound, nuclear medicine hepatobiliary testing, allergy evaluation, resting pulmonary function testing (PFT), resting electrocardiogram (ECG), and resting echocardiogram were unrevealing. Her past medical, surgical and family history was also unrevealing. Her physical exam was normal including thorough cardiopulmonary evaluation. It was decided to proceed with a nongraded treadmill stress test to attempt to elicit her presyncopal symptoms. She ran for 15 minutes at 8 miles per hour with 7.5% grade. She was asymptomatic throughout the test. ECG, heart rate, and blood pressure response were normal pre, during, and post-test, as were pre and post PFTs. While the test was not a maximal test, her peak VO2max was excellent and far exceeded her age predicted value. Given the thorough laboratory workup and cardiac workup to date, further testing was not recommended. She was diagnosed with exercise swoon in the setting of OTS. It was recommended she take a prolonged break from training, abstain from competitive running for the coming collegiate year, and slowly resume training thereafter. During her several months break from running she participated informally in other noncompetitive physical activities. After a four month period, she began to reintegrate into a training program and has not had reoccurrence of any symptoms. It is advised that she and her coaches maintain training and performance logs to more readily identify subtle drops in performance which may signal subsequent episodes of OTS.

OTS is a complex syndrome characterized by a decline in performance due to an imbalance in training loads and recovery capacity. Training load excess can be related to excess intensity, volume, competition, and/or emotional stress. Inadequate recovery can be due to poor nutrition, lack of sleep, and/or alcohol or drug use [1,2]. As seen in this case, OTS most commonly occurs in endurance athletes [1,2]. While the hallmark of OTS is a performance decrement in the face of high intensity training, OTS can also lead to nonspecific dysfunction in multiple body systems. Autonomic nervous system dysfunction can cause alterations in resting and training heart rate and blood pressure, fatigue, and changes in catecholamine release. Endocrine abnormalities can lead to changes in menstrual cycle and reproductive function. Psychiatric disturbance can include anhedonia, depressed mood, and sleep disturbances. OTS is a diagnosis of exclusion, thus workup depends on excluding more common or concerning conditions based on patient symptoms [2,3]. Potential differential diagnose include infectious etiology such as Epstein-Barr virus, hematologic abnormalities such as anemia, thyroid dysfunction, eating disorders, and musculoskeletal injury [1,3]. Management of OTS involves a prolonged break from training, often requiring six months or more of time. Prevention of OTS, therefore, is key [3]. Prevention can be achieved through appropriate periodization of training and monitoring of performance over time to identify early decrements in performance [1,3].

Exercise swoon is a rare type of vasovagal syncope thought to be caused by the Bezold-Jarish reflex. The reflex is precipitated by a sympathetic nervous system surge in someone who has decreased cardiac preload. In exercise swoon, as demonstrated by the present case, the sympathetic surge is caused by competition and the decreased preload is due to dehydration and complex features related to a Pavlovian type of subconscious anticipation. The Bezold-Jarish reflex triggers bradycardia, hypotension, and apnea rendering the exercising athlete incapable of continuing to perform. The athlete then slowly lowers or “swoons” to the ground without sustaining injury. Features consistent with exercise swoon include sensation of pre-syncope without actual loss of consciousness, occurrence in competition and not practice due to the enhanced sympathetic component, and prolonged recovery to baseline while the autonomic system re-equilibrates. Much like OTS, management of exercise swoon requires a prolonged break from training.

In the present case, the athlete demonstrated common signs of OTS including deterioration in performance, fatigue, amenorrhea, depressed mood, anhedonia, and sleep disturbances. Dysfunction of the autonomic nervous system from OTS likely predisposed her to developing exercise swoon, in addition to the preceding episode of benign exertional collapse generating a Pavlovian type of response for subsequent episodes. She was managed successfully with a several month break from sport and slow reintegration thereafter into training.

1. Meeusen R, Duclos M, Foster C, Fry A, Gleeson M, Nieman D, et al. Prevention, diagnosis, and treatment of the overtraining syndrome: join consensus statement of the European College of Sport Science and the American College of Sports Medicine. Med Sci Sports Exerc. 2013; 45: 186-205.

2. Carfagno DG, Hendrix JC. Overtraining syndrome in the athlete: current clinical practice. Curr Sports Med Rep. 2014; 13: 45-51.

3. Finnoff JT, Harrast MA. 2nd Edn. Sports Medicine: Study Guide and Review for Boards. Springer Publishing Company. 2016