Mitochondrial coupling efficiency and myofiber type related to blood pressure 22 h after high-intensity exercise in premenopausal women

Previously we have shown that systolic blood pressure (SBP) increases in African American (AA) women but decreases in European American (EA) women ≈22 h after a high-intensity exercise bout, suggesting delayed recovery in the AA women. We, therefore, sought to determine whether myofiber type, systemic vascular resistance (SVR), and mitochondrial coupling efficiency may contribute to elevated blood pressure in AA women following a bout of high-intensity exercise. Premenopausal EA (9) and AA (7) women were aerobically trained for 8-16 weeks and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mover><mml:mi>V</mml:mi> <mml:mo>˙</mml:mo></mml:mover> <mml:msub><mml:mtext>O</mml:mtext> <mml:mtext>2peak</mml:mtext></mml:msub> </mml:mrow> </mml:math> was evaluated. After 2 days without exercise, participants were evaluated for myofiber type, mitochondrial respiration using high-resolution respirometry, and SVR 22 h following 1 h of high-intensity interval cycle ergometry. AAs had higher SBP and DBP and type IIx myofiber % but lower type IIa myofiber %. SBP was significantly related to SVR (0.71), RCR (0.44), type IIa myofiber type (- 0.48), and type IIx myofiber type (0.53). DBP was significantly related to SVR (0.58) and the respiratory acceptor control ratio (state 3/state 4, termed RCR, 0.69). SBP remained significantly higher in AAs even after adjusting for type IIx myofiber type, RCR, SVR, or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mover><mml:mi>V</mml:mi> <mml:mo>˙</mml:mo></mml:mover> <mml:msub><mml:mtext>O</mml:mtext> <mml:mtext>2peak</mml:mtext></mml:msub> </mml:mrow> </mml:math> adjusted for FFM, and additionally, DBP remained significantly higher after adjusting for type IIx myofiber type, RCR, or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mover><mml:mi>V</mml:mi> <mml:mo>˙</mml:mo></mml:mover> <mml:msub><mml:mtext>O</mml:mtext> <mml:mtext>2peak</mml:mtext></mml:msub> </mml:mrow> </mml:math> adjusted for FFM. These results support the premise that mitochondrial RCR, type IIx myofiber type, and SVR may contribute to increased blood pressure ≈22 h following a bout of high-intensity exercise. Still, racial differences were not explained by any of these variables.