Low-Volume Intense Exercise Elicits Post-exercise Hypotension and Subsequent Hypervolemia, Irrespective of Which Limbs Are Exercised

Abstract

Introduction: Exercise reduces arterial and central venous blood pressures during recovery, which contributes to its valuable anti-hypertensive effects and to facilitating hypervolemia. Repeated sprint exercise potently improves metabolic function, but its cardiovascular effects (esp. hematological) are less well-characterized, as are effects of exercising upper versus lower limbs. The purposes of this study were to identify the acute (<24 h) profiles of arterial blood pressure and blood volume for (i) sprint intervals versus endurance exercise, and (ii) sprint intervals using arms versus legs.

Methods: Twelve untrained males completed three cycling exercise trials; 50-min endurance (legs), and 5(*)30-s intervals using legs or arms, in randomized and counterbalanced sequence, at a standardized time of day with at least 8 days between trials. Arterial pressure, hemoglobin concentration and hematocrit were measured before, during and across 22 h after exercise, the first 3 h of which were seated rest.

Results: The post-exercise hypotensive response was larger after leg intervals than endurance (AUC: 7540 ± 3853 vs. 3897 ± 2757 mm Hg·min, p = 0.049, 95% CI: 20 to 6764), whereas exercising different limbs elicited similar hypotension (arms: 6420 ± 3947 mm Hg·min, p = 0.48, CI: -1261 to 3896). In contrast, arterial pressure at 22 h was reduced after endurance but not after leg intervals (-8 ± 8 vs. 0 ± 7 mm Hg, p = 0.04, CI: 7 ± 7) or reliably after arm intervals (-4 ± 8 mm Hg, p = 0.18 vs. leg intervals). Regardless, plasma volume expansion at 22 h was similar between leg intervals and endurance (both +5 ± 5%; CI: -5 to 5%) and between leg and arm intervals (arms: +5 ± 7%, CI: -8 to 5%).

Conclusions: These results emphasize the relative importance of central and/or systemic factors in post-exercise hypotension, and indicate that markedly diverse exercise profiles can induce substantive hypotension and subsequent hypervolemia. At least for endurance exercise, this hypervolemia may not depend on the volume of post-exercise hypotension. Finally, endurance exercise led to reduced blood pressure the following day, but sprint interval exercise did not.

Keywords: HIIT; arm exercise; blood pressure; exercise training; plasma volume; sprint exercise.

Figure 1

Schematic of the experimental timeline. , continuous heart rate and beat-to-beat blood pressure recordings, M, manual blood pressure measurement; , blood sample drawn (every 15 min after exercise except at T2:45); and , standardized meal fed to participants.

Figure 2

Profile of change from pre-exercise baseline for systolic (SBP), mean arterial (MAP) and diastolic (DBP) blood pressure, and plasma volume for one participant, across the period from baseline (BL) through to 22 h following each of the three different exercise conditions. Blood pressure measures taken at 8 and 22 h are manual (man) recordings.

Figure 3

Volume of hypotension following exercise of different type (Endurance, Intervals_Legs) or different limbs used (Intervals_{Legs or Arms}). Data are mean ± SD (bars) and individual responses (lines) of area under the curve (AUC) for the change in mean arterial pressure (MAP), for 12 participants. AUC is calculated from immediately following exercise until MAP returned through baseline.

Figure 4

Blood pressure change from baseline (BL) to 22 h following each of three exercise conditions. Data are the individual response (gray lines) and mean (black dashed line) of 12 participants, with all measures taken at the same time of day, in a standardized seated position.

Figure 5

Change in plasma volume from baseline (BL) to 8 and 22 h following each exercise condition. Data are the individual response (gray lines) and mean (black dashed line) of 12 participants, with all measures taken at the same time of day, in a standardized seated position, while fasted (BL and 22 h) or post prandial (8 h). Plasma volume change was measured via the hemoglobin-hematocrit method.

Figure 6

Relation between the Change in Plasma Volume at 22 h after exercise, and the volume of the preceding post-exercise hypotension. Symbols are individual responses and the line is the corresponding linear regression. See text for further detail.