Relationship between aerobic fitness and metabolic recovery from intermittent exercise in endurance athletes .

This investigation examined the relationship between several different aerobic fitness test results and measurements of metabolic recovery from intermittent, high-intensity exercise in 16 male cyclists. No significant correlations were found between maximal oxygen consumption, ventilation threshold, various submaximal endurance measures and the rate of metabolic recovery, net excess postexercise oxygen consumption, or blood lactate removal after intermittent high-intensity exercise except for submaximal heart rate (r = .66, p < .05). These data indicate that aerobic fitness assessments do not indicate the ability to recover after intermittent, high-intensity exercise in endurance-trained cyclists.

Changes in blood pressure and cardiac output during maximal isokinetic exercise.

This study was undertaken to determine the blood pressure (BP) and cardiac output (Qc) responses to maximal isokinetic exercise. The subjects (n = 5) performed unilateral knee extension/flexion exercise (knee exercise) and unilateral elbow extension/flexion exercise (elbow exercise) at 0.52, 1.57, and 2.62 rads.sec-1. The BP was monitored using a cannula placed in the radial artery. Heart rate (HR), stroke volume (SV), and Qc were measured by impedance cardiography. In response to isokinetic exercise, HR and Qc increased significantly (p less than .01), while the SV did not. The BP response was characterized by significant increases in systolic, diastolic, and mean arterial pressure (MAP) (p less than .01). The Qc and MAP, responses were not influenced by the exercise velocity. The adjustments in HR, MAP, and rate pressure product (RPP) to the elbow exercise were qualitatively similar to those seen during the knee exercise, but the absolute values achieved were smaller (p less than .05). Compared with maximal dynamic exercise, the HR and SV responses to the knee exercises were lower. The MAP response to isokinetic exercise equaled the highest value achieved during dynamic exercise. Findings from the present study suggest that the cardiovascular stress (the increase in HR, MAP, and RPP) associated with isokinetic exercise is independent of the velocity of movement and is proportional to the active muscle mass.

Short-term cardiovascular adaptations to vertical head-down suspension.

Inversion devices have been advocated as means of therapy for patients with low back pain. The present investigation was undertaken to determine the cardiovascular responses to vertical head-down suspension with such a device. Eight men were monitored for three minutes in the upright and supine position, and for ten minutes in the vertical head-down position. Stroke volume (SV), heart rate (HR), cardiac output (QT), segmental arm blood flow (ABF), and segmental leg blood flow (LBF) were measured by impedance plethysmography. Moving from the upright to the supine positions resulted in an SV increase from 93.1 +/- 18.8 to 138.2 +/- 28.2 ml.beat-1 (p less than 0.01). During the first minute of suspension a further increase in SV to a maximum of 178.6 +/- 45.0 ml.beat-1 was noted. By the end of the suspension period, SV had declined to 159.6 +/- 34.2 ml.beat-1. Resumption of the upright position was associated with a reduction in SV to 94.3 +/- 15.8 ml.beat-1. Changes in QT across the supine and vertical head-down positions reflected the changes in SV. The vertical head-down position was also associated with a gradual reduction in both ABF and LBF. These data suggest that the primary effect of inverted suspension was a transient increase in venous return, which requires an effective ventricular response. An element of caution should be exercised in using these devices to avoid aggravating concurrent pathologic conditions.