Autonomic regulation of heart rate response to exercise in Tibetan and Han residents of Lhasa (3,658 m)

1993 ◽  
Vol 75 (5) ◽  
pp. 1968-1973 ◽  
Author(s):  
J. Zhuang ◽  
T. Droma ◽  
J. R. Sutton ◽  
R. E. McCullough ◽  
R. G. McCullough ◽  
...  
Keyword(s):  
Heart Rate ◽  
High Altitude ◽  
Minute Ventilation ◽  
Random Order ◽  
Work Load ◽  
Cycle Ergometer ◽  
O2 Consumption ◽  
Tibet Autonomous Region ◽  
Ergometer Exercise ◽  
Response To Exercise

To test the hypothesis that native high-altitude residents have less beta-sympathetic and more parasympathetic tone than newcomers, we compared the effects of beta-sympathetic and parasympathetic blockade in 10 Tibetan and 9 Han acclimatized male residents of Lhasa, Tibet Autonomous Region, China (elevation 3,658 m). Each subject was studied during cycle ergometer exercise at 70, 132, and 191 W after placebo (normal saline), beta-sympathetic (propranolol, 0.2 mg/kg iv), or parasympathetic (atropine, 0.04 mg/kg iv) blockade in random order on different days. At rest, the fall in resting heart rate with propranolol and the rise with atropine were equal in Tibetan and Han subjects. During exercise, the fall in heart rate with propranolol relative to placebo values was greater in the Han than in the Tibetan group, whereas the rise in heart rate with atropine was greater in the Tibetans. Propranolol or atropine administration did not change minute ventilation per unit O2 consumption in either group. At the highest level of exercise on the placebo day, the Tibetans achieved a higher work load and level of O2 consumption than the Han subjects. Propranolol or atropine reduced O2 consumption and work load similarly in the two groups at the highest exercise level. The results supported our hypothesis that native Tibetan residents of high altitude exhibit more para-sympathetic and less beta-sympathetic tone during exercise. Neither relatively greater parasympathetic nor less sympathetic activation appeared implicated in the greater exercise capacity of Tibetans compared with that of acclimatized newcomer residents of high altitude.

Effect of beta-blockade on the drift in O2 consumption during prolonged exercise

1988 ◽  
Vol 64 (2) ◽  
pp. 753-758 ◽  
Author(s):  
J. K. Kalis ◽  
B. J. Freund ◽  
M. J. Joyner ◽  
S. M. Jilka ◽  
J. Nittolo ◽  
...  
Keyword(s):  
Heart Rate ◽  
Minute Ventilation ◽  
Cycle Ergometer ◽  
Beta Blockade ◽  
Adrenergic Blockade ◽  
Maximal Heart Rate ◽  
O2 Consumption ◽  
Double Blind ◽  
Cycle Ergometer Test ◽  
Ergometer Test

The effect of beta-adrenergic blockade on the drift in O2 consumption (VO2 drift) typically observed during prolonged constant-rate exercise was studied in 14 healthy males in moderate heat at 40% of maximal O2 consumption (VO2max). After an initial maximum cycle ergometer test to determine the subjects' control VO2max, subjects were administered each of three medications: placebo, atenolol (100 mg once daily), and propranolol (80 mg twice daily), in a randomized double-blind fashion. Each medication period was 5 days in length and was followed by a 4-day washout period. On the 3rd day of each medication period, subjects performed a maximal cycle ergometer test. On the final day of each medication period, subjects exercised at 40% of their control VO2max for 90 min on a cycle ergometer in a warm (31.7 +/- 0.3 degrees C) moderately humid (44.7 +/- 4.7%) environment. beta-Blockade caused significant (P less than 0.05) reductions in VO2max, maximal minute ventilation (VEmax), maximal heart rate (HRmax), and maximal exercise time. Significantly greater decreases in VO2max, VEmax, and HRmax were associated with the propranolol compared with the atenolol treatment. During the 90-min submaximal rides, beta-blockade significantly reduced heart rate. Substantially lower values for O2 consumption (VO2) and minute ventilation (VE) were observed with propranolol compared with atenolol or placebo. Furthermore, VO2 drift and HR drift were observed under atenolol and placebo conditions but not with propranolol. Respiratory exchange ratio decreased significantly over time during the placebo and atenolol trials but did not change during the propranolol trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Breathing pattern during exercise in young black and Caucasian subjects

1987 ◽  
Vol 62 (6) ◽  
pp. 2220-2223 ◽  
Author(s):  
F. J. Cerny
Keyword(s):  
Lung Volume ◽  
Breathing Pattern ◽  
Minute Ventilation ◽  
Cycle Ergometer ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Ergometer Exercise ◽  
Residual Capacity ◽  
Response To Exercise ◽  
Adaptation To Exercise

Lung volumes in sex-, age-, height-, and weight-matched Black subjects are 10–15% lower than those in Caucasians. To determine whether this decreased lung volume affected the ventilatory adaptation to exercise, minute ventilation (VE), its components, frequency (f) and tidal volume (VT), and breathing pattern were observed during incremental cycle-ergometer exercise. Eighteen Caucasian (age 8–30 yr) and 14 Black (age 8–25 yr) subjects were studied. Vital capacity (VC) was lower (P less than 0.001) in the Black subjects [90.6 +/- 8.6 (SD) vs. 112.9 +/- 9.9% predicted], whereas functional residual capacity/total lung capacity was higher (P less than 0.05). VE, mixed expired O2 and CO2, VT, f, and inspiratory (TI), expiratory (TE), and total respiratory cycle (TT) duration were measured during the last 30 s of each 2-min load. Statistical comparisons with increasing power output were made at rest and from 0.6 to 2.4 W/kg in 0.3-W/kg increments. VE was higher in Blacks at all work loads and reached significance (P less than 0.05) at 0.6 and 1.5 W/kg. VE/VO2 was also higher throughout exercise, reaching significance (P less than 0.01) at 1.2, 1.5, and 1.8 W/kg. The Black subjects attained any given level of VE with a higher f (P less than 0.001) and lower VT. TI and TE were shortened proportionately so that TI/TT was not different. Differences in lung volume and the ventilatory response to exercise in these Black and Caucasian subjects suggest differences in the respiratory pressure-volume relationships or that the Black subjects may breathe higher on their pressure-volume curve.

Excess lactate concept and oxygen debt of exercise

1965 ◽  
Vol 20 (6) ◽  
pp. 1299-1306 ◽  
Author(s):  
Karlman Wasserman ◽  
George G. Burton ◽  
Antonius L. Van Kessel
Keyword(s):  
Metabolic Rate ◽  
Anaerobic Metabolism ◽  
Work Load ◽  
Cycle Ergometer ◽  
O2 Consumption ◽  
Arterial Blood ◽  
Arterial Blood Lactate ◽  
Ergometer Exercise ◽  
Prolonged Duration ◽  
O2 Debt

The Huckabee concept that “excess lactate” (XL) is equivalent to the O2 debt of exercise and physiological phenomena derived therefrom, were investigated. Measurements of O2 debt, arterial blood lactate and XL, and O2 consumption were made during cycle ergometer exercise of controlled intensity and duration. Our results indicate: 1) The oxygen equivalents of XL as well as Delta lactate are less than the O2 debt, at all work loads. 2) The concentration of XL does not linearly increase during exercise. 3) The anaerobic metabolic rate whether calculated from XL or O2 debt is not a constant fraction of the metabolic rate, at all work loads. A larger fraction of energy is derived from the O2 debt creditors at heavy and very heavy than at moderate work loads. 4) In 30 controlled work-load exercise studies of prolonged duration, XL did not contribute any information not revealed by lactate itself. 5) The differences between Huckabee's results and those of our own are not due to differences in the measurement of XL but rather to differences in the directly measured O2 debt. anaerobic metabolism; O2 debt creditors; O2 consumption Submitted on January 4, 1965

Cardio-Respiratory Response to Exercise in Normal Children

1971 ◽  
Vol 40 (5) ◽  
pp. 419-431 ◽  
Author(s):  
S. Godfrey ◽  
C. T. M. Davies ◽  
E. Wozniak ◽  
Carolyn A. Barnes
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Steady State ◽  
Minute Ventilation ◽  
Work Load ◽  
Normal Children ◽  
Progressive Exercise ◽  
Maximum Work ◽  
Response To Exercise ◽  
Submaximal Heart Rate

1. The results of studies during simple progressive exercise to exhaustion and steady-state submaximal exercise in 117 boys and girls aged 6–16 years are presented. 2. In the simple progressive exercise test, the highest work load achieved and the submaximal heart rate were related to size and sex. The maximum heart rate and submaximal ventilation were largely independent of size and sex. 3. Steady-state exercise was performed at one-third and two-thirds of the maximum work load achieved in the simple progressive test. The Indirect (CO2) Fick method was used to measure cardiac output. 4. At any given level of steady-state work, tidal volume, dead space, heart rate and stroke volume were closely related to size, with girls having higher heart rates and smaller stroke volumes than boys. Minute ventilation and cardiac output were virtually independent of size and sex. The cardiac output in children was the same as that in the adult for any given oxygen consumption. Blood lactate was related to size at any given work load, but was independent of size at any given fraction of the maximum working capacity.

scholarly journals Associations of the serum long-chain n-3 PUFA and hair mercury with resting heart rate, peak heart rate during exercise and heart rate recovery after exercise in middle-aged men

2017 ◽  
Vol 119 (1) ◽  
pp. 66-73 ◽  
Author(s):  
Behnam Tajik ◽  
Sudhir Kurl ◽  
Tomi-Pekka Tuomainen ◽  
Kai Savonen ◽  
Jyrki K. Virtanen
Keyword(s):  
Heart Rate ◽  
Disease Risk ◽  
Heart Rate Recovery ◽  
Population Based ◽  
Cycle Ergometer ◽  
Resting Heart Rate ◽  
Middle Aged ◽  
Hair Mercury ◽  
Ergometer Exercise ◽  
Long Chain

AbstractLong-chain n-3 PUFA from fish have been associated with lower risk of CVD. Fish may also contain methylmercury, which may attenuate the inverse associations of the long-chain n-3 PUFA. However, the mechanisms underlying these associations are not fully known. We evaluated the associations of the serum long-chain n-3 PUFA (EPA, DPA and DHA) and hair Hg with resting heart rate (HR), peak HR during cycle ergometer exercise and HR recovery after exercise. A total of 1008 men from the population-based Kuopio Ischaemic Heart Disease Risk Factor Study, aged 42–60 years and free of CVD, were studied. After multivariate-adjustments in ANCOVA, higher serum total long-chain n-3 PUFA concentration was associated with lower resting HR (extreme-quartile difference 2·2 beats/min; 95 % CI 0·2, 4·1, Ptrend across quartiles=0·02), but not with peak HR or HR recovery. Associations were generally similar when EPA, DPA and DHA were evaluated individually, except for DPA, which was also associated with better HR recovery after exercise (extreme-quartile difference 2·1 beats/min; 95 % CI 0·1, 4·2, Ptrend=0·06). Higher hair Hg content had a trend towards lower peak HR after adjusting for the long-chain n-3 PUFA (Ptrend=0·05), but it only slightly attenuated the associations of the serum long-chain n-3 PUFA with HR. These findings suggest that higher serum long-chain n-3 PUFA concentrations are associated with lower resting HR in middle-aged men from Eastern Finland, which may partially explain the potential cardioprotective effect of fish intake.

Cardiovascular response to cycle exercise during and after pregnancy

1989 ◽  
Vol 66 (1) ◽  
pp. 336-341 ◽  
Author(s):  
S. P. Sady ◽  
M. W. Carpenter ◽  
P. D. Thompson ◽  
M. A. Sady ◽  
B. Haydon ◽  
...  
Keyword(s):  
Heart Rate ◽  
Maximal Exercise ◽  
Cardiovascular Response ◽  
Work Load ◽  
Cycle Ergometry ◽  
Maximal Heart Rate ◽  
O2 Uptake ◽  
Cycle Exercise ◽  
Vascular Beds ◽  
Response To Exercise

Our purpose was to determine if pregnancy alters the cardiovascular response to exercise. Thirty-nine women [29 +/- 4 (SD) yr], performed submaximal and maximal exercise cycle ergometry during pregnancy (antepartum, AP, 26 +/- 3 wk of gestation) and postpartum (PP, 8 +/- 2 wk). Neither maximal O2 uptake (VO2max) nor maximal heart rate (HR) was different AP and PP (VO2 = 1.91 +/- 0.32 and 1.83 +/- 0.31 l/min; HR = 182 +/- 8 and 184 +/- 7 beats/min, P greater than 0.05 for both). Cardiac output (Q, acetylene rebreathing technique) averaged 2.2 to 2.8 l/min higher AP (P less than 0.01) at rest and at each exercise work load. Increases in both HR and stroke volume (SV) contributed to the elevated Q at the lower exercise work loads, whereas an increased SV was primarily responsible for the higher Q at higher levels. The slope of the Q vs. VO2 relationship was not different AP and PP (6.15 +/- 1.32 and 6.18 +/- 1.34 l/min Q/l/min VO2, P greater than 0.05). In contrast, the arteriovenous O2 difference (a-vO2 difference) was lower at each exercise work load AP, suggesting that the higher Q AP was distributed to nonexercising vascular beds. We conclude that Q is greater and a-vO2 difference is less at all levels of exercise in pregnant subjects than in the same women postpartum but that the coupling of the increase in Q to the increase in systemic O2 demand (VO2) is not different.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate ingestion before exercise: comparison of glucose, fructose, and sweet placebo

1981 ◽  
Vol 51 (4) ◽  
pp. 783-787 ◽  
Author(s):  
V. A. Koivisto ◽  
S. L. Karonen ◽  
E. A. Nikkila
Keyword(s):  
Plasma Glucose ◽  
Plasma Insulin ◽  
Cycle Ergometer ◽  
Vo2 Max ◽  
Vigorous Exercise ◽  
Carbohydrate Ingestion ◽  
Rapid Fall ◽  
Ergometer Exercise ◽  
Glucose Ingestion ◽  
Response To Exercise

To examine the effect of various carbohydrates on the metabolic and hormonal response to exercise, 75 g glucose, fructose, or placebo were given to nine well-trained males (VO2 max 60 +/- 1 ml . kg-1 . min-1) 45 min before cycle ergometer exercise performed at 75% VO2 max for 30 min. After glucose ingestion, the rise in plasma glucose was 3-fold (P less than 0.005) in plasma insulin 2.5-fold (P less than 0.01) greater than after fructose. During exercise, after glucose administration plasma glucose fell from 5.3 +/- 0.3 to 2.5 +/- 0.2 mmol/l (P less than 0.001) and after fructose from 4.5 +/- 0.1 to 3.9 +/- 0.3 mmol/l (P less than 0.05). The fall in plasma glucose was closely related to the preexercise levels of plasma insulin (r = 0.82, P less than 0.001) and glucose (r = 0.81, P less than 0.001). Both glucose and fructose ingestion decreased the FFA levels by 40–50% (P less than 0.005) and during exercise they remained 30–40% lower after carbohydrate than placebo administration (P less than 0.02). This study suggests that glucose ingestion prior to exercise results in hypoglycemia during vigorous exercise, this rapid fall in plasma glucose is mediated, at least in part, by hyperinsulinemia, and fructose ingestion is associated with a modest rise in plasma insulin and does not result in hypoglycemia during exercise.

scholarly journals Metabolic, Cardiac, and Hemorheological Responses to Submaximal Exercise under Light and Moderate Hypobaric Hypoxia in Healthy Men

Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 144
Author(s):  
Hun-Young Park ◽  
Jeong-Weon Kim ◽  
Sang-Seok Nam
Keyword(s):  
Oxygen Uptake ◽  
Blood Lactate ◽  
Minute Ventilation ◽  
Random Order ◽  
Cycle Ergometer ◽  
Submaximal Exercise ◽  
Erythrocyte Deformability ◽  
Moderate Hypoxia ◽  
Healthy Men ◽  
Significant Difference

We compared the effects of metabolic, cardiac, and hemorheological responses to submaximal exercise under light hypoxia (LH) and moderate hypoxia (MH) versus normoxia (N). Ten healthy men (aged 21.3 ± 1.0 years) completed 30 min submaximal exercise corresponding to 60% maximal oxygen uptake at normoxia on a cycle ergometer under normoxia (760 mmHg), light hypoxia (596 mmHg, simulated 2000 m altitude), and moderate hypoxia (526 mmHg, simulated 3000 m altitude) after a 30 min exposure in the respective environments on different days, in a random order. Metabolic parameters (oxygen saturation (SPO2), minute ventilation, oxygen uptake, carbon dioxide excretion, respiratory exchange ratio, and blood lactate), cardiac function (heart rate (HR), stroke volume, cardiac output, and ejection fraction), and hemorheological properties (erythrocyte deformability and aggregation) were measured at rest and 5, 10, 15, and 30 min after exercise. SPO2 significantly reduced as hypoxia became more severe (MH > LH > N), and blood lactate was significantly higher in the MH than in the LH and N groups. HR significantly increased in the MH and LH groups compared to the N group. There was no significant difference in hemorheological properties, including erythrocyte deformability and aggregation. Thus, submaximal exercise under light/moderate hypoxia induced greater metabolic and cardiac responses but did not affect hemorheological properties.

Effects of pregnancy and chronic exercise on maternal cardiac structure and function

1999 ◽  
Vol 77 (11) ◽  
pp. 909-917 ◽  
Author(s):  
L A Wolfe ◽  
R J Preston ◽  
G W Burggraf ◽  
M J McGrath
Keyword(s):  
Heart Rate ◽  
Resting State ◽  
Cycle Ergometer ◽  
Structure And Function ◽  
Cardiac Structure ◽  
Cycle Ergometer Exercise ◽  
Ergometer Exercise ◽  
Aerobic Conditioning ◽  
Cardiac Structure And Function ◽  
And Function

This study examined the interactive effects of pregnancy and aerobic conditioning on maternal cardiac structure and function. Effects of closely monitored cycle ergometer conditioning were studied during the second (TM2) and third trimesters (TM3) in 22 previously sedentary pregnant women (exercised group, EG) and a nonexercising pregnant control group with similar characteristics (CG, n = 19). Subjects were studied in the resting state by two-dimensional echocardiography and during cycle ergometer exercise at three steady-state power outputs at the start of TM2 (ENTRY), at the end of TM2 and TM3 (postconditioning), and 3-4 months postpartum (NPR, nonpregnant reference, CG only). Aerobic conditioning did not increase left ventricular dimensions beyond those attributable to pregnancy itself. In addition, in contrast with previous studies of nonpregnant women, physical conditioning during pregnancy did not reduce heart rate (HR) in the resting state. During exercise, the slope of the HR versus oxygen uptake (Vo2) regression decreased significantly between preconditioning and the end of TM3 in the EG, suggesting that training-induced reductions in HR become more evident with increasing exercise intensity. Also, significant reductions in oxygen pulse (Vo2/HR) were observed at all three work rates in the CG, but not in the EG. These findings support the hypothesis that the cardiovascular effects of aerobic conditioning are obscured by more powerful effects of pregnancy in the resting state but become "unmasked" during strenuous exercise.Key words: human gestation, cycle ergometer exercise, echocardiography, heart rate, stroke volume.

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