Background: The purpose of this study was to characterize intestinal temperature (T(in)) in comparison to esophageal (T(es)) and rectal temperature (T(re)) during supine exercise.
Methods: Seven subjects completed a continuous supine protocol of 20 min of rest, 20 min of cycle exercise at 40% peak oxygen consumption (V(O2peak)), 20 min of cycle exercise at 65G% V(O2peak), and 20 min of recovery. T(es), T(re), and T(in) were recorded each min.
Results: Temperatures were not different after 20 min of rest, but T(es) and T(in) were greater than T(re) at the end of the 40% (T(es): 37.38 +/- 0.11; T(in): 37.35 +/- 0.06; T(re): 37.20 +/- 0.10 degrees C) and 65% V(O2peak) stages (T(es): 37.83 +/- 0.10; T(in): 37.75 +/- 0.05; T(re): 37.63 +/- 0.08 degrees C). After 20 min of recovery, T(es) (37.24 +/- 0.011 degrees C) was less than either T(re) or T(in), which were not different from each other (T(in): 37.39 +/- 0.09; T(re): 37.44 +/- 0.09 degrees C). Time to threshold for increased temperature from rest (+0.10 degrees C) for T(es) (10.0 +/- 1.1 min) was not different from T(in) (14.0 +/- 1.2 min) but less than T(re) (15.7 +/- 1.6 min). Time to reach peak temperature was less for T(es) (36.6 +/- 1.8 min) than T(in) (40.6 +/- 0.9 min) and T(re) (41.4 +/- 0.5 min). Similarly, time to a decrease in temperature (-0.10 degrees C) after exercise was less for T(es) (3.7 +/- 0.4 min) than T(in) (7.1 +/- 1.5 min) and T(re) (10.6 +/- 1.9).
Conclusions: Measurement of T(in) may be an alternative to T(es) to measure T(core) specific time points during exercise with an understanding of the slower response of Tin compared with T(es).