Nineteen healthy volunteers, 10 men and nine women (mean age 38 and 30 years), exercised on a treadmill. The systolic blood pressure (BP) was measured at the ankle and in the arm after submaximal (8 min with a final load of 2 W kg-1 body weight) and maximal exercise. The BP was measured for 10 min after exercise, or until the elimination of a negative pressure difference between ankle and arm. The pre-study resting systolic arm and ankle pressures were 122 +/- 11 and 144 +/- 13 mmHg. One minute after submaximal exercise, arm and ankle BP were 147 +/- 18 and 159 +/- 19 mmHg (ankle-arm pressure difference 12 +/- 13 mmHg); 1 min after maximal exercise the corresponding figures were 182 +/- 26 and 153 +/- 35 mmHg (ankle-arm pressure difference -29 +/- 33 mmHg). We conclude that maximal exercise, but not an appropriately chosen submaximal exercise level, causes a negative BP difference between ankle and arm in normal people.