Thermoregulatory observations in soccer match play: professional and recreational level applications using an intestinal pill system to measure core temperature

Background: Technological limitations associated with oesophageal and rectal temperature probes have previously limited match play observations of body temperature. Objective: To investigate the application of an intestinal pill system to measure core temperature during dynamic, field based, soccer matches. Methods: Core temperature (Tc) was assessed using the intestinal pill system (CorTemp 2000) and changes in plasma volume were calculated using the values for haemoglobin and packed cell volume obtained before and after recreational (n = 8) and the professional soccer (n = 7) matches. Results: In the recreational match, there were significant post-match reductions in body mass (−1.6%, p<0.05) and plasma volume (−7.2%, p<0.01). Significant increases were observed in Tc from rest to half time (p<0.01) and from half time to full time (p<0.05). In the professional match, body mass decreased by 1.9% (p<0.05) and plasma volume by 11.6% (p<0.01). Tc increased from rest to half time (p