Higher exercise intensity delays postexercise recovery of impedance-derived cardiac sympathetic activity

2017 ◽  
Vol 42 (8) ◽  
pp. 834-840 ◽  
Author(s):  
Scott Michael ◽  
Ollie Jay ◽  
Kenneth S. Graham ◽  
Glen M. Davis
Keyword(s):  
Heart Rate ◽  
Neural Activity ◽  
Exercise Intensity ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Natural Logarithm ◽  
Ventricular Ejection Time

Systolic time intervals (STIs) provide noninvasive insights into cardiac sympathetic neural activity (cSNA). As the effect of exercise intensity on postexercise STI recovery is unclear, this study investigated the STI recovery profile after different exercise intensities. Eleven healthy males cycled for 8 min at 3 separate intensities: LOW (40%–45%), MOD (75%–80%), and HIGH (90%–95%) of heart-rate (HR) reserve. Bio-impedance cardiography was used to assess STIs – primarily pre-ejection period (PEP; inversely correlated with cSNA), as well as left ventricular ejection time (LVET) and PEP:LVET – during 10 min seated recovery immediately postexercise. Heart-rate variability (HRV), i.e., natural-logarithm of root mean square of successive differences (Ln-RMSSD), was calculated as an index of cardiac parasympathetic neural activity (cPNA). Higher preceding exercise intensity elicited a slower recovery of HR and Ln-RMSSD (p < 0.001), and these measures did not return to baseline by 10 min following any intensity (p ≤ 0.009). Recovery of STIs was also slower following higher intensity exercise (p ≤ 0.002). By 30 s postexercise, higher preceding intensity resulted in a lower PEP (98 ± 14 ms, 75 ± 6 ms, 66 ± 5 ms for LOW, MOD, and HIGH, respectively, p < 0.001). PEP recovered to baseline (143 ± 11 ms) by 5 min following LOW (139 ± 13 ms, p = 0.590) and by 10 min following MOD (145 ± 17 ms, p = 0.602), but was still suppressed at 10 min following HIGH (123 ± 21 ms, p = 0.012). Higher preceding exercise intensity attenuated the recovery of indices for cSNA (from STIs) and cPNA (from HRV) in a graded dose–response fashion. While exercise intensity must be considered, acute recovery may be a valuable period during which to concurrently monitor these noninvasive indices, to identify potentially abnormal cardiac autonomic responses.

Dynamics of cardiac output and systolic time intervals in supine and upright exercise

1983 ◽  
Vol 55 (6) ◽  
pp. 1674-1681 ◽  
Author(s):  
Y. Miyamoto ◽  
J. Higuchi ◽  
Y. Abe ◽  
T. Hiura ◽  
Y. Nakazono ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Response Times ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Upright Posture ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Supine Posture ◽  
Ventricular Ejection Time

Transient and steady-state responses of stroke volume (SV), heart rate (HR), cardiac output (Q), left ventricular ejection time (LVET), preejection period (PEP), and the ratio of LVET to PEP during bicycle exercises of 50 and 100 W were studied in four healthy male subjects in supine and upright postures. A computer-based system in which impedance cardiography was incorporated served to determine the above parameters on a 10-s interval basis. SV remained almost unchanged in response to exercises in a supine posture, whereas it increased significantly in an upright posture, although the individual differences among subjects were found to be large. The half-response times of variables to a step work load were determined. An approximate accordance was observed among the response times for HR, Q, and LVET/PEP. There was an inverse relationship between LVET and HR, the slope of which was found to be steeper in the supine posture than in the upright posture, reflecting the difference between the SV responses in both postures. LVET fell shortly after the cessation of exercise despite the decreasing HR. Inasmuch as the paradoxical reduction of LVET was also found in the case where SV remained unchanged in response to exercise, no changes in SV can be the cause thereof. Thus, a transient increase in ejection rate, which is due to either the increased myocardial contractility or decreased peripheral vascular resistance, may be responsible for the phenomenon.

Left ventricular ejection time index in man

1963 ◽  
Vol 18 (5) ◽  
pp. 919-923 ◽  
Author(s):  
Arnold M. Weissler ◽  
Leonard C. Harris ◽  
George D. White
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Time Index ◽  
Normal Individuals ◽  
Ventricular Ejection Time

The present studies were undertaken in an attempt to formulate an accurate expression of the relationship between the duration of left ventricular ejection and heart rate in man. On the basis of regression equations relating the duration of left ventricular ejection and heart rate in normal individuals, the index LVET + .0016 HR was derived and tested in normal adults and prepubertal children. The left ventricular ejection time index (ETI) remained constant and reproducible over the range of heart rate from 50 to 150 and yielded more consistent values in this range of heart rate than did previously derived equations. A slight but significantly higher value of the ETI was present in the adult females when compared to the adult males, while no significant difference according to sex was apparent in the children. A decrease in ETI was found when cardiac output was diminished in normal individuals during 60° head-up tilt and in patients with congestive heart failure. Of note was the finding of a significant correlation between the level of the ETI and the cardiac output in these situations. Submitted on December 13, 1962

SYSTOLIC TIME INTERVALS (STI) AS INDICATORS OF MYOCARDIAL THYROID HORMONE EFFECT

1978 ◽  
Vol 87 (3) ◽  
pp. 507-515 ◽  
Author(s):  
J. Chakravarty ◽  
A. R. Guansing ◽  
S. Chakravarty ◽  
C. V. Hughes
Keyword(s):  
Thyroid Hormone ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Hormone Effect ◽  
Systolic Time ◽  
Ventricular Ejection Time

ABSTRACT Systolic time intervals consisting of indices of electromechanical systole (QS2-I), left ventricular ejection time (LVET-I) and pre-ejection period (PEP-I) were calculated serially during therapy in 12 euthyroid, 9 hypothyroid and 9 hyperthyroid individuals. These parameters were analyzed sequentially together with the changes in serum thyroxine (T4), triiodothyronine (T3) and thyrotrophin (TSH) in order to determine the sensitivity of these non-invasive procedures in monitoring peripheral thyroid hormone effect. The results are expreseed in mean ± sem. QS2-I (506.3 ± 8.2 ms) and PEP-I (102.9 ± 4.2) were shortened (P < 0.02 and P < 0.001, respectively) in hyperthyroidism and prolonged (579.3 ± 7.3 and 169.6 ± 3.6 ms) in hypothyroidism (P < 0.01 and P < 0.001, respectively) compared to euthyroid controls (538.1 ± 8.8 and 130.3 ± 5.3 ms), while LVET-I did not change significantly in either condition. Simultaneous determinations of circulating T4, T3 and TSH showed changes appropriate to both hypo- and hyperthyroid states. In 2 patients with T3-thyrotoxicosis, PEP-I was decreased to an average of 103.1 ms, while in 2 patients with compensated hypothyroidism (normal T4 but elevated TSH) this was prolonged to 163.7 ms (average) compared to euthyroid controls. During treatment the hypothyroid group showed significant sequential correlation of TSH and PEP-I. In the hyperthyroid individuals, PEP-I correlated significantly with T4 and T3. PEP-I may be a useful, sensitive, quantitative biologic indicator of thyroid hormone effect on myocardial function.

Constant-load versus heart rate-targeted exercise: responses of systolic intervals

1975 ◽  
Vol 38 (5) ◽  
pp. 794-800 ◽  
Author(s):  
V. Q. Lance ◽  
D. H. Spodick
Keyword(s):  
Heart Rate ◽  
Work Load ◽  
Constant Load ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Normal Male ◽  
Bicycle Ergometry ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Ventricular Ejection Time

Eight normal male volunteers were studied during bicycle ergometry at constant work loads of 50, 100, and 150 W for 4 min each and heart rate-targeted exercise to rates which matched those during the end of the 4th min at each constant work load. Systolic intervals measured prior to and during exercise included: Q-IM, isovolumic contraction time (IVCT), preejection period (PEP), left ventricular ejection time (LVET), ejection time index (ETI), PEP/LVET, and pulse transmission time (PTT). Directional changes during both exercise methods were consistent with previously reported results. Comparable control values indicated equivalent starting points for each bout and confirmed recovery from preceding exercise. There was striking similarities within each matched exercise set for Q-IM, IVCT, PEP, and PEP/LVET. LVET was significantly shorter for rate targeted exercise. We conclude that either constant-load or rate-targeted bicycle ergometry may be employed with choice of method determined by the purpose of the protocol and that systoloc intervals (except LVET) should not be importantly altered owing to the method chosen.

Reliability of noninvlasive methods for measuring cardiac function in exercise

1978 ◽  
Vol 44 (1) ◽  
pp. 55-58 ◽  
Author(s):  
L. A. Wolfe ◽  
D. A. Cunningham ◽  
G. M. Davis ◽  
P. A. Rechnitzer
Keyword(s):  
Cardiac Output ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Ejection Rate ◽  
Systolic Time ◽  
Ventricular Ejection Time

Externally recorded systolic time intervals (STI's), indirect (CO2 re-breathing) cardiac output, and auscultatory blood pressures were measured during upright bicycle ergometer work in 20 healthy men, aged 24–56 yr. The subjects were studied on 2 separate days at steady-state work loads chosen to represent light (mean heart rate (HR) = 96 beats.min-1), moderate (HR = 118 beats.min-1) and heavy (HR = 147 beats.min-1) exercise. In addition to determinations of cardiac output, systolic time intervals, and blood pressure, the individual's mean systolic ejection rate (stroke volume/left ventricular ejection time) was calculated as a measure of left ventricular function. In general, heart-rate-corrected STI's were found to be reliable and reproducible. Reliability coefficients for total electromechanical systole and left ventricular ejection time ranged from 0.93 to 0.96 while those for the preejection period and its subcomponents were between 0.63 and 0.88. The reliability of cardiac output, stroke volume, mean systolic ejection rate, and systolic blood pressure was also considered to be acceptable but tended to be higher during moderate and heavy work (r = 0.85–0.95) compared to light exercise (r = 0.60–0.83).

Systolic Time Intervals before and after Maximal Exercise in Adolescents with Insulin-Dependent Diabetes Mellitus

1992 ◽  
Vol 4 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Barbara N. Campaigne ◽  
Kyle W. Landt ◽  
Frederick W. James ◽  
Joan Reimar ◽  
Wayne Mays ◽  
...  
Keyword(s):  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Dependent Diabetes Mellitus ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Before And After ◽  
Systolic Time ◽  
Ventricular Ejection Time

Systolic time intervals (STI) were measured before and after exercise in 18 diabetic adolescents (D) and 18 age- and sex-matched nondiabetic controls (C). At similar heart rates, pre-exercise pre-ejection period (PEP) and left ventricular ejection time (LVET) were significantly shorter in D compared to C (p<0.05). There was no difference between the two groups in the PEP/LVET ratio. Following exercise there were no differences in STIs between groups. However, the change in PEP and LVET from pre- to postexercise was significantly less in D compared to C (delta PEP 38 vs. 53±3 msec, p<0.01; delta LVET 120 vs. 134±4 msec, p<0.05). These data suggest a hypercontractile state at rest in D and a blunted response to exercise when compared to C. This study provides data that may be relevant to the early identification of individuals at risk for premature diabetic cardiomyopathy.

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