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Acute cardiac functional and mechanical responses to isometric exercise in prehypertensive males

View Article: PubMed Central - PubMed

ABSTRACT

Isometric exercise (IE) training has been shown to reduce resting arterial blood pressure (ABP) in hypertensive, prehypertensive, and normotensive populations. However, the acute hemodynamic response of the heart to such exercise remains unclear. We therefore performed a comprehensive assessment of cardiac structure, function, and mechanics at rest and immediately post a single IE session in 26 male (age 44.8 ± 8.4 years) prehypertensive participants. Conventional echocardiography recorded standard and tissue Doppler measures of left ventricular (LV) structure and function. Speckle tracking echocardiography was used to measure LV global longitudinal, circumferential, and radial strain and strain rate. From this data, apical and basal rotation and rotational velocities, LV twist, systolic twist velocity, untwist velocity, and torsion were determined. IE led to a significant post exercise reduction in systolic (132.6 ± 5.6 vs. 109.4 ± 19.6 mmHg, P < 0.001) and diastolic (77.6 ± 9.4 vs. 58.8 ± 17.2 mmHg, P < 0.001) blood pressure, with no significant change in heart rate (62 ± 9.4 vs. 63 ± 7.5b·min−1, P = 0.63). There were significant reductions in LV end systolic diameter (3.4 ± 0.2 vs. 3.09 ± 0.3 cm, P = 0.002), LV posterior wall thickness (0.99 ± 0.1 vs. 0.9 ± 0.1 cm, P = 0.013), relative wall thickness (0.4 ± 0.06 vs. 0.36 ± 0.05, P = 0.027) estimated filling pressure (E/E' ratio 6.08 ± 1.87 vs. 5.01 ± 0.82, P = 0.006) and proportion of participants with LV concentric remodeling (30.8% vs. 7.8%, P = 0.035), and significant increases in LV ejection fraction (60.8 ± 3 vs. 68.3 ± 4%, P < 0.001), fractional shortening (31.6 ± 4.5 vs. 39.9 ± 5%, P < 0.001), cardiac output (4.3 ± 0.7 vs. 6.1 ± 1L·min−1, P < 0.001), and stroke volume (74.6 ± 11 vs. 96.3 ± 13.5 ml, P < 0.001). In this setting, there were significant increases in global longitudinal strain (−17.8 ± 2.4 vs. −20 ± 1.8%, P = 0.002) and strain rate (−0.88 ± 0.1 vs. −1.03 ± 0.1%, P < 0.001), basal rotation (−5 ± 3.5 vs. −7.22 ± 3.3°, P = 0.047), basal systolic rotational velocity (−51 ± 21.9 vs. −79.3 ± 41.3°·s−1, P = 0.01), basal diastolic rotational velocity (48.7 ± 18.9 vs. 62.3 ± 21.4°·s−1, P = 0.042), LV twist (10.4 ± 5.8 vs. 13.8 ± 5°, P = 0.049), systolic twist velocity (69.6 ± 27.5 vs. 98.8 ± 35.8°·s−1, P = 0.006), and untwist velocity (−64.2 ± 23 vs. −92.8 ± 38°·s−1, P = 0.007). These results suggest that IE improves LV function and mechanics acutely. This may in turn be partly responsible for the observed reductions in ABP following IE training programs and may have important implications for clinical populations.

No MeSH data available.


Sequential representation of left ventricular twist, basal, and apical rotation pre and post isometric exercise training. Annotations indicate key findings and for clarity, statistical differences have not been displayed; refer to Table 2. Note: AVC, aortic valve closure.
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phy213236-fig-0003: Sequential representation of left ventricular twist, basal, and apical rotation pre and post isometric exercise training. Annotations indicate key findings and for clarity, statistical differences have not been displayed; refer to Table 2. Note: AVC, aortic valve closure.

Mentions: Myocardial mechanics pre and post IE are displayed in Table 2. Global longitudinal strain (−17.8 ± 2.4 vs. −20 ± 1.8%, P = 0.002) and strain rate (−0.88 ± 0.1 vs. −1.03 ± 0.1%·s−1, P < 0.001) significantly increased post IE with no difference in global longitudinal diastolic strain rate (1.26 ± 0.3 vs. 1.37 ± 0.3%·s−1, P = 0.259). There was a significant increase in both basal and apical circumferential strain (−28.9 ± 5.4 vs. −34.8 ± 6.3%, P = 0.003 and −25.3 ± 4.1 vs. −32.9 ± 7.6%, P < 0.001, respectively) and strain rate (−2.3 ± 0.5 vs. −2.8 ± 0.6%·s−1, P = 0.009 and −2.04 ± 0.5 vs. −2.57 ± 0.7%·s−1, P = 0.012) and significant increase in apical radial strain (35.4 ± 16.4 vs. 55 ± 17.8%, P = 0.001). There was a significant increase in basal rotation (−5 ± 3.5 vs. −7.22 ± 3.3°, P = 0.047), basal systolic rotational velocity (−51 ± 21.9 vs. −79.3 ± 41.3°·s−1, P = 0.01), and basal diastolic rotational velocity (48.7 ± 18.9 vs. 62.3 ± 21.4°·s−1, P = 0.042); however, there was no significant change in apical rotation, apical systolic rotational velocity, and apical diastolic rotational velocity. The increase in basal mechanics translated into a significant increase in LV twist (10.4 ± 5.8 vs. 13.8 ± 5 °, P = 0.049), systolic twist velocity (69.6 ± 27.5 vs. 98.8 ± 35.8 °·s−1, P = 0.006), untwist velocity (−64.2 ± 23 vs. −92.8 ± 38 °·s−1, P = 0.007), and LV length‐corrected torsion (1.46 ± 0.86 vs. 2.07 ± 0.88 °·cm−1, P = 0.032). Figure 3 displays the composite twist, basal and apical rotation and rotational velocity curves with annotations indicating key findings.


Acute cardiac functional and mechanical responses to isometric exercise in prehypertensive males
Sequential representation of left ventricular twist, basal, and apical rotation pre and post isometric exercise training. Annotations indicate key findings and for clarity, statistical differences have not been displayed; refer to Table 2. Note: AVC, aortic valve closure.
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phy213236-fig-0003: Sequential representation of left ventricular twist, basal, and apical rotation pre and post isometric exercise training. Annotations indicate key findings and for clarity, statistical differences have not been displayed; refer to Table 2. Note: AVC, aortic valve closure.
Mentions: Myocardial mechanics pre and post IE are displayed in Table 2. Global longitudinal strain (−17.8 ± 2.4 vs. −20 ± 1.8%, P = 0.002) and strain rate (−0.88 ± 0.1 vs. −1.03 ± 0.1%·s−1, P < 0.001) significantly increased post IE with no difference in global longitudinal diastolic strain rate (1.26 ± 0.3 vs. 1.37 ± 0.3%·s−1, P = 0.259). There was a significant increase in both basal and apical circumferential strain (−28.9 ± 5.4 vs. −34.8 ± 6.3%, P = 0.003 and −25.3 ± 4.1 vs. −32.9 ± 7.6%, P < 0.001, respectively) and strain rate (−2.3 ± 0.5 vs. −2.8 ± 0.6%·s−1, P = 0.009 and −2.04 ± 0.5 vs. −2.57 ± 0.7%·s−1, P = 0.012) and significant increase in apical radial strain (35.4 ± 16.4 vs. 55 ± 17.8%, P = 0.001). There was a significant increase in basal rotation (−5 ± 3.5 vs. −7.22 ± 3.3°, P = 0.047), basal systolic rotational velocity (−51 ± 21.9 vs. −79.3 ± 41.3°·s−1, P = 0.01), and basal diastolic rotational velocity (48.7 ± 18.9 vs. 62.3 ± 21.4°·s−1, P = 0.042); however, there was no significant change in apical rotation, apical systolic rotational velocity, and apical diastolic rotational velocity. The increase in basal mechanics translated into a significant increase in LV twist (10.4 ± 5.8 vs. 13.8 ± 5 °, P = 0.049), systolic twist velocity (69.6 ± 27.5 vs. 98.8 ± 35.8 °·s−1, P = 0.006), untwist velocity (−64.2 ± 23 vs. −92.8 ± 38 °·s−1, P = 0.007), and LV length‐corrected torsion (1.46 ± 0.86 vs. 2.07 ± 0.88 °·cm−1, P = 0.032). Figure 3 displays the composite twist, basal and apical rotation and rotational velocity curves with annotations indicating key findings.

View Article: PubMed Central - PubMed

ABSTRACT

Isometric exercise (IE) training has been shown to reduce resting arterial blood pressure (ABP) in hypertensive, prehypertensive, and normotensive populations. However, the acute hemodynamic response of the heart to such exercise remains unclear. We therefore performed a comprehensive assessment of cardiac structure, function, and mechanics at rest and immediately post a single IE session in 26 male (age 44.8&nbsp;&plusmn;&nbsp;8.4&nbsp;years) prehypertensive participants. Conventional echocardiography recorded standard and tissue Doppler measures of left ventricular (LV) structure and function. Speckle tracking echocardiography was used to measure LV global longitudinal, circumferential, and radial strain and strain rate. From this data, apical and basal rotation and rotational velocities, LV twist, systolic twist velocity, untwist velocity, and torsion were determined. IE led to a significant post exercise reduction in systolic (132.6&nbsp;&plusmn;&nbsp;5.6 vs. 109.4&nbsp;&plusmn;&nbsp;19.6&nbsp;mmHg, P&nbsp;&lt;&nbsp;0.001) and diastolic (77.6&nbsp;&plusmn;&nbsp;9.4 vs. 58.8&nbsp;&plusmn;&nbsp;17.2&nbsp;mmHg, P&nbsp;&lt;&nbsp;0.001) blood pressure, with no significant change in heart rate (62&nbsp;&plusmn;&nbsp;9.4 vs. 63&nbsp;&plusmn;&nbsp;7.5b&middot;min&minus;1, P&nbsp;=&nbsp;0.63). There were significant reductions in LV end systolic diameter (3.4&nbsp;&plusmn;&nbsp;0.2 vs. 3.09&nbsp;&plusmn;&nbsp;0.3&nbsp;cm, P&nbsp;=&nbsp;0.002), LV posterior wall thickness (0.99&nbsp;&plusmn;&nbsp;0.1 vs. 0.9&nbsp;&plusmn;&nbsp;0.1&nbsp;cm, P&nbsp;=&nbsp;0.013), relative wall thickness (0.4&nbsp;&plusmn;&nbsp;0.06 vs. 0.36&nbsp;&plusmn;&nbsp;0.05, P&nbsp;=&nbsp;0.027) estimated filling pressure (E/E' ratio 6.08&nbsp;&plusmn;&nbsp;1.87 vs. 5.01&nbsp;&plusmn;&nbsp;0.82, P&nbsp;=&nbsp;0.006) and proportion of participants with LV concentric remodeling (30.8% vs. 7.8%, P&nbsp;=&nbsp;0.035), and significant increases in LV ejection fraction (60.8&nbsp;&plusmn;&nbsp;3 vs. 68.3&nbsp;&plusmn;&nbsp;4%, P&nbsp;&lt;&nbsp;0.001), fractional shortening (31.6&nbsp;&plusmn;&nbsp;4.5 vs. 39.9&nbsp;&plusmn;&nbsp;5%, P&nbsp;&lt;&nbsp;0.001), cardiac output (4.3&nbsp;&plusmn;&nbsp;0.7 vs. 6.1&nbsp;&plusmn;&nbsp;1L&middot;min&minus;1, P&nbsp;&lt;&nbsp;0.001), and stroke volume (74.6&nbsp;&plusmn;&nbsp;11 vs. 96.3&nbsp;&plusmn;&nbsp;13.5&nbsp;ml, P&nbsp;&lt;&nbsp;0.001). In this setting, there were significant increases in global longitudinal strain (&minus;17.8&nbsp;&plusmn;&nbsp;2.4 vs. &minus;20&nbsp;&plusmn;&nbsp;1.8%, P&nbsp;=&nbsp;0.002) and strain rate (&minus;0.88&nbsp;&plusmn;&nbsp;0.1 vs. &minus;1.03&nbsp;&plusmn;&nbsp;0.1%, P&nbsp;&lt;&nbsp;0.001), basal rotation (&minus;5&nbsp;&plusmn;&nbsp;3.5 vs. &minus;7.22&nbsp;&plusmn;&nbsp;3.3&deg;, P&nbsp;=&nbsp;0.047), basal systolic rotational velocity (&minus;51&nbsp;&plusmn;&nbsp;21.9 vs. &minus;79.3&nbsp;&plusmn;&nbsp;41.3&deg;&middot;s&minus;1, P&nbsp;=&nbsp;0.01), basal diastolic rotational velocity (48.7&nbsp;&plusmn;&nbsp;18.9 vs. 62.3&nbsp;&plusmn;&nbsp;21.4&deg;&middot;s&minus;1, P&nbsp;=&nbsp;0.042), LV twist (10.4&nbsp;&plusmn;&nbsp;5.8 vs. 13.8&nbsp;&plusmn;&nbsp;5&deg;, P&nbsp;=&nbsp;0.049), systolic twist velocity (69.6&nbsp;&plusmn;&nbsp;27.5 vs. 98.8&nbsp;&plusmn;&nbsp;35.8&deg;&middot;s&minus;1, P&nbsp;=&nbsp;0.006), and untwist velocity (&minus;64.2&nbsp;&plusmn;&nbsp;23 vs. &minus;92.8&nbsp;&plusmn;&nbsp;38&deg;&middot;s&minus;1, P&nbsp;=&nbsp;0.007). These results suggest that IE improves LV function and mechanics acutely. This may in turn be partly responsible for the observed reductions in ABP following IE training programs and may have important implications for clinical populations.

No MeSH data available.