The case of the water polo player's shoulder—Clinical reasoning, assessment and management

Abstract

of central neurotransmission in the heat might contribute to elucidate the mechanisms of fatigue. Studies from our lab showed that DA significantly enhanced performance, coinciding with the attainment of high core temperatures and heart rates, without any change in thermosensation and in the perception of effort. 2,3 In contrast, increased brain concentration of Noradrenaline (NA) strongly decreased performance in the heat and no effect of 5-HT could be detected. 4,5 Thermal regulation appears to be an important factor that will mainly be influenced by brain DA and NA in the PO/AH, although the exact role of other neurotransmitter systems is not clear so far. 6 It is very unlikely that one neurotransmitter system is responsible for the appearance of central fatigue. Most probably central fatigue is caused by a complex interplay between the different neurotransmitters systems, with the most important role for the catecholamines DA and NA. Although work to date has given us clear observations on external behavioural changes after pharmacological interventions, the exact role of the different brain areas linked to exercise capacity and thermoregulation have yet to be elucidated.