Testosterone, cortisol and catecholamine responses to exercise stress and autonomic dysreflexia in elite quadriplegic athletes

Abstract

Episodes of short high intensity exercise are associated with an increase in circulating total testosterone (T) in men. Mechanisms may include hemoconcen tration, decreased metabolic clearance and/or increased synthesis. Beta-blockade abolishes the T response suggesting a direct beta-adrenergic effect on the testes. Some spinal cord injured (SCI) athletes deliberately induce autonomic dysre flexia (boosting) to enhance performance. Associated with this practice are elevated catecholamine (CA) levels and exaggerated responses to serum cate cholamine levels. Since basal T levels are reported to be normal in the SCI male, the T response to acute high intensity exercise might be expected to be exaggerated by boosting and associated elevated CA levels. The acute exercise T response has not been examined in SCI men to date. To determine whether the increased CA values associated with boosting enhanced the exercise-induced T elevation we measured circulating levels of T, cortisol (C), norepinephrine (NE) and epinephrine (E) before and after maximal exertion and a simulated 7.S km race with and without boosting in eight elite quadriplegic athletes. Maximal incremental exercise and a simulated 7.S km race resulted in a rise in T similar to able bodied men under normal exercise conditions. Under boosted conditions the rise in T was eliminated while NE levels were significantly elevated above unboosted levels. The data may suggest an inhibitory role for CA on T production or release under conditions of extreme stress. Other possible mechanisms include C induced suppression, impaired gonadotropin stimulation of the Leydig cell and CA mediated alterations in gonadal blood supply.

Cortisol and testosterone concentrations in wheelchair athletes during submaximal wheelchair ergometry

“…Plasma TEST concentration at the end of exercise appeared to have increased during upper body exercise in the WA, whereas it appeared to have decreased in the AB group. Similar ®ndings have been observed by Wheeler et al (1994) who reported an increase in TEST concentration in quadriplegics following maximal exercise and a simulated 7.5 km race. However, in able-bodied individuals, there is a standing controversy as TEST concentration has been reported to increase during treadmill exercise (Wilkerson et al 1980) and cycle ergometry (Maresh et al 1988), whereas other groups have reported the contrary (Morville et al 1979).…”

“…However, the increase in TEST concentration in the WA is unlikely to have been due to this mechanism, since NE concentration increased to the same extent in both groups but TEST concentration increased only in the WA group. Indeed, in wheelchair athletes, higher catecholamine concentrations following`b oosting'' have been demonstrated to decrease the plasma TEST response to exercise (Wheeler et al 1994). The relationship between relative exercise intensity and TEST responses during upper body exercise is not yet known and our ®ndings could be due to a low exercise intensity for the AB subjects compared to the WA group.…”

Insulin resistance and sympathetic function in high spinal cord injury

“…Induction of an autonomic dysre¯exia reaction, so called`boosting', is commonly used by SCI athletes 46 and improved results especially during long-distance Insulin resistance and sympathetic function in SCI A-K Karlsson races are reported.`Boosting' is accompanied by increased NA levels. 47 Our investigations suggest an increased supply of substrates for metabolism during boosted' conditions.…”

Catecholamine response to exercise in individuals with different levels of paraplegia

“…Several investigators have reported lower blood levels of Nor and Epi for quadriplegics at rest (10,11,13,14), during tilting (10,15,16) and exercise (12,17). It has already been established that quadriplegics have an impairment of peripheral SNS activation that justifies their lack of catecholamine response to exercise, but they also have a less active muscle mass in the upper extremities that might contribute to these findings.…”