Temperature changes in deep muscles of humans during upper and lower extremity exercise.

OBJECTIVE

To examine the effect of 15 minutes of upper and lower extremity exercise on raising intramuscular temperature in the triceps surae to 39 degrees C to 45 degrees C (the therapeutic range).

DESIGN AND SETTING

Intramuscular temperature was measured 5 cm deep in the triceps surae using a 23-gauge thermistor needle microprobe connected to a monitor. Each subject was tested under 3 conditions: 15 minutes of rest, 15 minutes of jogging on a treadmill, and 15 minutes of handpedaling an upper-body ergometer. Exercise bouts were performed at 70% of each subject's maximum heart rate.

SUBJECTS

Six males, either sedentary or recreational athletes (age = 21.3 +/- 2.9 years; ht = 176.8 +/- 6.0 cm; wt = 72.7 +/- 11.6 kg; resting heart rate = 57.8 +/- 6.74 bpm; target heart rate = 156.5 +/- 3.0 bpm), volunteered to participate in this experiment.

MEASUREMENTS

Intramuscular temperature was measured at a depth of 5 cm before and after each test condition.

RESULTS

Data analyses consisted of analyses of variance with repeated measures and a Tukey post hoc test (P < .05). The results showed a significant temperature increase over baseline after exercise on the treadmill (2.2 degrees C +/- 0.63 degrees C); however, it did not yield temperature increases >/= 39 degrees C. No significant temperature change occurred after exercise on the upper-body ergometer (-0.45 degrees C +/- 0.80 degrees C).

CONCLUSIONS

Active exercise increased intramuscular temperature in working muscles but did not affect intramuscular temperature in nonworking muscles. In addition, 15 minutes of jogging on a treadmill at 70% of maximum heart rate was not sufficient to raise intramuscular temperature to 39 degrees C to 45 degrees C.