Rectal and esophageal temperatures during upper- and lower-body exercise

Area of Science:

• Exercise Physiology
• Human Thermoregulation

Background:

• Accurate core body temperature measurement is crucial for understanding physiological responses to exercise.
• Different exercise modalities, such as upper-body versus lower-body dominant activities, may influence thermoregulatory responses.
• Rectal temperature (T(re)) and esophageal temperature (T(es)) are common measures of core body temperature.

Purpose of the Study:

• To investigate whether the type of exercise musculature (upper-body vs. lower-body) affects core temperature measurement.
• To compare the validity of rectal temperature (T(re)) as an estimate of core temperature across different exercise types.

Main Methods:

• Healthy men performed incremental exercise tests to determine maximum oxygen consumption (VO2max).
• Subjects then completed 36 minutes of submaximal exercise (approx. 65% VO2max) using treadmill (lower-body), cycle (lower-body), or arm crank (upper-body) ergometry.
• Rectal (T(re)) and esophageal (T(es)) temperatures were simultaneously measured during exercise.

Main Results:

• Maximum oxygen consumption (VO2max) was significantly lower in the arm crank (upper-body) group compared to treadmill and cycle groups (lower-body).
• At rest, T(re) was significantly higher than T(es) across all groups.
• At the end of submaximal exercise, T(re) was significantly higher than T(es) only in the cycle ergometry group.
• The temperature difference between T(re) and T(es) approached 0.2°C for all groups by the end of steady-state exercise.

Conclusions:

• Rectal temperature (T(re)) can serve as a valid estimate of core temperature during steady-state exercise.
• This validity holds true irrespective of whether the exercise predominantly involves upper- or lower-body musculature.
• The findings support the use of T(re) for monitoring core temperature in diverse exercise conditions.