Sports syncope is a sudden, transient loss of consciousness, loss of muscle tone with fall caused by a momentary lack of blood supply to the brain or changes in blood chemicals during or after exercise. These include vascular decompression syncope, gravitational shock syncope, postural hypotensive syncope, episodic muscle weakness, primary loss of consciousness, and other types.
Vascular decompression syncope
Also known as vagal reflex syncope or simple syncope, its incidence accounts for the first of all types of syncope. Mood swings, mental stimulation or competition injuries can induce transient vasodilation through vagal reflexes, resulting in a decrease in cardiac blood return and cardiac output, a drop in blood pressure, and a lack of blood supply to the brain, resulting in syncope, which is usually seen in athletes who are younger or less experienced in competition, and is more common in women. This type of syncope occurs when athletes are recovering from injury, overexerting themselves, or suddenly participating in high-intensity training or competition after a break in training. The prodromal symptoms include dizziness, sweating, nausea, pallor, limb weakness, etc. The above symptoms last for tens of seconds to minutes before LOC occurs, and can awaken on its own after a few seconds to tens of seconds. Physical examination is free of organic disease and no sequelae.
Gravitational shock syncope
When an athlete performs lower limb-based exercise, the lower limb muscle oxygen consumption increases and capillaries dilate. If the exercise is abruptly stopped after strenuous exercise, a large amount of blood will pool in the lower limb blood vessels and the cerebral blood supply will be insufficient, triggering syncope, mostly seen in track and field events. Precursory symptoms include dizziness, weakness, nausea, pallor, cold extremities, and in severe cases, fainting.
Postural hypotensive syncope
When the horizontal position suddenly changes to upright position, the muscle pump function and vascular regulation dysfunction may cause blood pooling in the lower extremities, resulting in transient cerebral ischemia, mostly occurring after swimming competitions. Sudden onset of LOC, without antecedent symptoms.
Onset muscle weakness
Also known as sudden onset weakness, it refers to sudden collapse due to temporary damage to the gravity-resistant extensor muscles of the extremities caused by a lowered response threshold of the central nervous system, mostly seen in rowing competitions. The athlete develops weakness followed by syncope a few minutes after completing the race, and the duration of the syncope is short, only a few seconds.
Primary loss of consciousness
Syncope due to abnormal nerve conduction direction caused by hypoxia and hypocapnia in the reticular tissue of brain cadres, often occurs after intense races and heavy training, such as long-distance races. The onset of syncope is accompanied by blurred consciousness, deeper LOC, longer duration of syncope, inability to remember the last moments of the race after waking up, and neurological symptoms such as aphasia after awakening.
Syncope due to hyperventilation syndrome
Due to excessive breathing or shortness of breath, excessive carbon dioxide excretion from the body can lead to respiratory alkalosis, which causes cerebral capillary constriction, ischemia and hypoxia of brain cells, and even syncope. Hyperventilation taken before diving and swimming to prepare for the closure of the air can cause syncope, which is the main cause of drowning in athletes.
Hypoglycemic syncope
The more common type of sports syncope, mostly seen in long-distance sports events. People with a history of hypoglycemia are prone to induce hypoglycemia during exercise. Precursory symptoms include hunger, weakness, sweating, dizziness, tachycardia, and confusion, etc. Consciousness can be restored quickly after glucose supplementation.
Cardiogenic syncope
Cardiac syncope is a dangerous but common type of syncope caused by various heart diseases (such as hypertrophic cardiomyopathy, coronary artery malformation, coronary artery disease, myocarditis, heart valve disease, Marfan syndrome, sinus node artery stenosis, pre-excitation syndrome, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy, etc.), followed by reduced heart beat volume and cerebral hypoxia, and is seen in soccer, basketball, cycling, tennis, ice hockey, marathon, etc. It is a dangerous but common type of syncope, which can be seen in football, basketball, cycling, tennis, hockey, marathon, etc.
Cerebral syncope
Syncope occurs when the blood vessels in the brain become extensively ischemic during exercise, and is seen in athletes and coaches with congenital malformations of the brain vessels, atherosclerosis, hypertension and cervical spondylosis. The attack is mostly accompanied by headache, vertigo, vomiting and sometimes aphasia, mild hemiparesis and loss of vision.
Heat stroke fainting
The body produces more heat during exercise, and due to the high temperature of the external environment, the body’s thermoregulatory ability decreases, resulting in elevated body temperature and multi-organ dysfunction, especially central nervous system dysfunction; in addition, massive sweating and dehydration, water and electrolyte imbalance in the body and reduced blood volume can also lead to syncope. The disease mostly occurs in high temperature and high humidity environments, and is mostly seen in long-distance running, marathon, cross-country running, cycling and soccer. Athletes are prone to dizziness, headache, chest tightness, thirst, nausea, vomiting, tachycardia and muscle spasms when training and competing in summer, when syncope and even death can occur if cooling measures are not taken.
Syncope due to increased intrathoracic and intrapulmonary pressure
Weight lifting process due to prolonged breath-holding force to increase thoracic pressure, left ventricular filling impairment, blood pressure drop, cerebral blood flow reduction, and then a transient syncope.
Patients with syncope should be treated actively for different causes. Once the preliminary symptoms of syncope appear during exercise, that is, with the help of others, jog or walk slowly for a distance, and then lie down for a while to wait for the body to gradually recover.
General treatment
The person who faints should lie on his back and elevate the lower limbs to increase cerebral blood flow, while loosening the collar and trouser belt and turning the head to the side. If necessary, give oxygen, and acupressure or acupuncture points such as Renzhong, Yongquan, Hegu, or sniff ammonia. Those with vascular decompression syncope, postural hypotensive syncope, episodic muscle weakness, and primary LOC can usually be relieved after receiving the above treatments.
Etiological treatment
In diving and swimming, the time from LOC to death generally does not exceed 2.5 minutes, and therefore should be resuscitated quickly.
Hypoglycemic syncope: intravenous injection of 50% glucose 60ml.
Cardiogenic syncope: immediate oxygen inhalation, anti-arrhythmic, anti-shock or anti-heart failure treatment according to the cause, and timely transfer to hospital.
Cerebral syncope: administer oxygen, keep the airway open, lower the cranial pressure, etc., and then transfer to the hospital.
Heat stroke syncope: move the patient to a cool and ventilated place quickly and give physical cooling.