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)

Effects of beta-adrenergic blockade on O2 uptake during submaximal and maximal exercise

1983 ◽  
Vol 54 (4) ◽  
pp. 901-905 ◽  
Author(s):  
P. A. Tesch ◽  
P. Kaiser
Keyword(s):  
Heart Rate ◽  
Maximal Exercise ◽  
Pulmonary Ventilation ◽  
Submaximal Exercise ◽  
Beta Blockade ◽  
Adrenergic Blockade ◽  
Maximal Heart Rate ◽  
O2 Consumption ◽  
O2 Uptake ◽  
Beta Adrenergic

Changes in cardiorespiratory variables and perceived rate of exertion (RPE) were studied in 13 trained men performing cycling exercise before and after beta-adrenergic blockade. Propranolol (Inderal, 80 mg) was administered orally 2 h prior to standardized maximal and submaximal exercises. Muscle biopsies were obtained from vastus lateralis at rest for subsequent histochemical analyses of muscle fiber type distribution and capillary supply. During submaximal exercise O2 consumption decreased from 2.76 to 2.59 l . min-1 following blockade (P less than 0.01), whereas heart rate decreased from 157 to 113 beats . min-1 (P less than 0.001). Maximal O2 uptake was lowered from 3.79 to 3.26 l . min-1 (P less than 0.001) and maximal heart rate was reduced from 192 to 142 beats . min-1 (P less than 0.001) as a result of the blockade. Pulmonary ventilation was unaltered in both exercise conditions. “Local” RPE was higher (P less than 0.001) than “central” RPE after beta-blockade in both submaximal and maximal exercise. During normal condition this difference did not appear. Changes in both local and central RPE during submaximal exercise were positively correlated to changes in O2 uptake. Individual variations in the metabolic profile of the exercising muscle had no influence on beta-blockade-induced changes in O2 uptake. It is concluded that blockade of beta-adrenergic receptors reduces O2 consumption during submaximal (approximately 73% maximal O2 uptake) and maximal exercise in habitually trained men.

Ambulatory Minute Ventilation Estimated from Heart Rate Monitoring in Girls

1992 ◽  
Vol 4 (2) ◽  
pp. 142-149
Author(s):  
Douglas A. Haines ◽  
Mark E. Raizenne
Keyword(s):  
Heart Rate ◽  
Minute Ventilation ◽  
Practical Method ◽  
Normal Activity ◽  
Cycle Ergometer ◽  
Prediction Equations ◽  
Heart Rate Monitoring ◽  
Cycle Ergometer Test ◽  
Ergometer Test

Models to indirectly estimate minute ventilation (V̇E) from heart rate (HR) monitored during normal activity were developed. VE-to-HR relationships were established from V̇E and HR measured in a graded cycle ergometer test performed by 99 girls, 7-14 years of age. The regression In V̇E = a + (b × HR) was a better predictor of V̇E, when individually determined, than were generalized prediction equations. V̇E, estimated by applying individual VE-to-HR regressions to HR monitored over 10 daytime hours, ranged between 11.5 and 14.5 L·min−1. This is a practical method of estimating V̇E, but further validation of the relationships with HR under various modes of exercise are necessary to improve the prediction in everyday settings.

Effects of beta-adrenergic blockade on ventilation and gas exchange during exercise in humans

1983 ◽  
Vol 54 (5) ◽  
pp. 1306-1313 ◽  
Author(s):  
E. S. Petersen ◽  
B. J. Whipp ◽  
J. A. Davis ◽  
D. J. Huntsman ◽  
H. V. Brown ◽  
...  
Keyword(s):  
Heart Rate ◽  
Gas Exchange ◽  
Time Constant ◽  
Minute Ventilation ◽  
Work Rate ◽  
Beta Blockade ◽  
Adrenergic Blockade ◽  
O2 Uptake ◽  
Beta Adrenergic ◽  
Co2 Partial Pressure

The effects of beta-adrenergic blockade induced by intravenous propranolol hydrochloride (0.2 mg/kg) on ventilatory and gas exchange responses to exercise were studied during tests in which the work rate was either increased progressively or maintained at a constant load in six healthy young male subjects. Heart rate during exercise decreased by about 20% and cardiac output, as estimated by a modification of the method of Kim et al. (J. Appl. Physiol. 21: 1338–1344, 1966), by about 15%. The relation between work rate and O2 uptake (VO2) was unaffected by propranolol, whereas maximal O2 uptake (VO2max) decreased by 5% and the anaerobic threshold, estimated noninvasively, was lowered by 23%. The relations between CO2 output (VCO2) and end-tidal CO2 partial pressure (PCO2) and between VCO2 and minute ventilation (VE) were both unaffected. The time constants for changes of VO2, VCO2, and VE during on-transients from unloaded pedaling to either a moderate (ca. 50% VO2max) or a heavy (ca. 67% VO2max) work rate in the control studies were in agreement with previously reported values, i.e., 42, 60, and 69 s, respectively. beta-Blockade was associated with a significantly increased time constant for VO2 of 61 s but with less consistent and insignificant changes for VCO2 and VE. There was a small but significant increase of the time constant for heart rate from 40 to 45 s. It is concluded that propranolol exerts its primary influence during exercise on the cardiovascular system without any discernible effect on ventilatory control.

Thermoregulation during prolonged exercise in heat: alterations with beta-adrenergic blockade

1987 ◽  
Vol 63 (3) ◽  
pp. 930-936 ◽  
Author(s):  
B. J. Freund ◽  
M. J. Joyner ◽  
S. M. Jilka ◽  
J. Kalis ◽  
J. M. Nittolo ◽  
...  
Keyword(s):  
Prolonged Exercise ◽  
Beta Blockers ◽  
Cycle Ergometer ◽  
Beta Blockade ◽  
Adrenergic Blockade ◽  
Sweat Loss ◽  
Double Blind ◽  
Beta Adrenergic ◽  
Cardiovascular Drift ◽  
Placebo Trial

Thermoregulation and cardiovascular drift were studied under conditions of prolonged exercise in a warm environment (dry bulb temperature 31.7 +/- 0.3 degrees C, rh 44.7 +/- 4.7%) during beta-adrenergic blockade. Fourteen subjects performed 90-min rides on a cycle ergometer at a work rate equivalent to 40% of their control maximal O2 uptake under each of three treatments provided in a randomized double-blind manner: atenolol (100 mg/day), propranolol (160 mg/day), and a placebo. Exercise during the propranolol trial resulted in significantly higher forearm vascular resistance values and significantly lower forearm blood flows (FBF) compared with the placebo trial. However, the significantly lower FBF during propranolol did not significantly alter the rectal temperature (Tre) response to prolonged exercise. In addition, both beta-blockers produced lower FBF for any given Tre, suggesting that beta-adrenergic blockade affects FBF through nonthermal factors. The slight differences in Tre, despite the large differences in FBF between the various treatments, are apparently the result of an enhanced sweat loss and a lower mean skin temperature during exercise with beta-blockade. The uncoupling of FBF and sweat loss provides evidence of independent regulation. The reduction in FBF at any given Tre was concomitant to lower blood pressure values during beta-blockade and suggests that baroreflexes provide significant input to the control of skin blood flow when both pressure and temperature maintenance are simultaneously challenged.

Exercise gas exchange in asthmatics after beta-adrenergic blockade

1983 ◽  
Vol 55 (2) ◽  
pp. 529-533 ◽  
Author(s):  
D. Y. Sue ◽  
L. R. Van Meter ◽  
J. E. Hansen ◽  
K. Wasserman
Keyword(s):  
Gas Exchange ◽  
Cardiovascular Response ◽  
Minute Ventilation ◽  
Work Rate ◽  
Incremental Exercise ◽  
Beta Blockade ◽  
Adrenergic Blockade ◽  
Maximal Heart Rate ◽  
Beta Adrenergic ◽  
Adrenergic Antagonist

Pharmacologic beta-adrenergic blockade reduces maximal heart rate (HR) during exercise but variable results have been reported for minute ventilation (VE), CO2 output (VCO2), and O2 uptake (VO2). A total group of 19 subjects with mild asthma was studied. We studied 16 subjects from the group who received placebo or pindolol, a beta-adrenergic antagonist, during 1-min incremental exercise on a cycle ergometer. During incremental exercise, HR, VE, VCO2, and VO2 were less after beta-blockade than after placebo at the same work rate below the anaerobic threshold. Maximal HR, VE, VO2, VCO2, and work rate were significantly less after beta-blockade. In addition, we studied six subjects from the group, including three who had also performed incremental exercise, during the steady state of constant-work cycling exercise. We found no difference in VE, VCO2, or VO2 although HR was less after beta-blockade. We conclude that beta-adrenergic blockade affects gas exchange by delaying the normal cardiovascular response to exercise. Decreased VE during incremental exercise is due to slowed delivery of CO2 load to the lungs rather than alterations in substrate, lung function, or ventilatory control.

Effect of naloxone on perceived exertion and exercise capacity during maximal cycle ergometry

2002 ◽  
Vol 93 (6) ◽  
pp. 2023-2028 ◽  
Author(s):  
Anthony L. Sgherza ◽  
Kenneth Axen ◽  
Randi Fain ◽  
Robert S. Hoffman ◽  
Christopher C. Dunbar ◽  
...  
Keyword(s):  
Exercise Capacity ◽  
Perceived Exertion ◽  
Minute Ventilation ◽  
Work Capacity ◽  
Cycle Ergometer ◽  
Endogenous Opioids ◽  
Opioid Antagonist ◽  
Double Blind ◽  
Cycle Ergometer Test ◽  
Physiological Limits

We assessed the effects of naloxone, an opioid antagonist, on exercise capacity in 13 men and 5 women (mean age = 30.1 yr, range = 21–35 yr) during a 25 W/min incremental cycle ergometer test to exhaustion on different days during familiarization trial and then after 30 mg (iv bolus) of naloxone or placebo (Pl) in a double-blind, crossover design. Minute ventilation (V˙e), O2 consumption (V˙o 2), CO2 production, and heart rate (HR) were monitored. Perceived exertion rating (0-10 scale) and venous samples for lactate were obtained each minute. Lactate and ventilatory thresholds were derived from lactate and gas-exchange data. Blood pressure was obtained before exercise, 5 min postinfusion, at maximum exercise, and 5 min postexercise. There were no control-Pl differences. The naloxone trial demonstrated decreased exercise time (96% Pl; P < 0.01), total cumulative work (96% Pl; P < 0.002), peakV˙o 2 (94% Pl; P < 0.02), and HR (96% Pl; P < 0.01). Other variables were unchanged. HR and V˙e were the same at the final common workload, but perceived exertion was higher (8.1 ± 0.5 vs. 7.1 ± 0.5) after naloxone than Pl ( P < 0.01). The threshold for effort perception amplification occurred at ∼60 ± 4% of Pl peakV˙o 2. Thus we conclude that peak work capacity was limited by perceived exertion, which can be attenuated by endogenous opioids rather than by physiological limits.

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.

Iron supplementation improves endurance after training in iron-depleted, nonanemic women

2000 ◽  
Vol 88 (3) ◽  
pp. 1103-1111 ◽  
Author(s):  
Pamela S. Hinton ◽  
Christina Giordano ◽  
Thomas Brownlie ◽  
Jere D. Haas
Keyword(s):  
Aerobic Exercise ◽  
Serum Ferritin ◽  
Iron Supplementation ◽  
Iron Status ◽  
Time Trial ◽  
Cycle Ergometer ◽  
Group Differences ◽  
Double Blind ◽  
Cycle Ergometer Test ◽  
Ergometer Test

Our objective was to investigate the effects of iron depletion on adaptation to aerobic exercise, assessed by time to complete a 15-km cycle ergometer test. Forty-two iron-depleted (serum ferritin <16 μg/l), nonanemic (Hb >12 g/dl) women (18–33 yr old) received 100 mg of ferrous sulfate (S) or placebo (P) per day for 6 wk in a randomized, double-blind trial. Subjects trained for 30 min/day, 5 days/wk at 75–85% of maximum heart rate for the final 4 wk of the study. There were no group differences in baseline iron status or in 15-km time. Iron supplementation increased serum ferritin and decreased transferrin receptors in the S compared with the P group. The S and P groups decreased 15-km time and respiratory exchange ratio and increased work rate during the 15-km time trial after training. The decrease in 15-km time was greater in the S than in the P group ( P = 0.04) and could be partially attributed to increases in serum ferritin and Hb. These results indicate that iron deficiency without anemia impairs favorable adaptation to aerobic exercise.

scholarly journals The UK Biobank submaximal cycle ergometer test for assessment of cardiorespiratory fitness: Validity, reliability, and association with disease outcomes

2020 ◽  
Author(s):  
Tomas I Gonzales ◽  
Kate Westgate ◽  
Tessa Strain ◽  
Stefanie Hollidge ◽  
Justin Jeon ◽  
...  
Keyword(s):  
Heart Rate ◽  
Health Outcomes ◽  
Dose Response ◽  
Heart Rate Response ◽  
Cycle Ergometer ◽  
Uk Biobank ◽  
Cycle Ergometer Test ◽  
Test Retest Reliability ◽  
Ergometer Test

Background: Cardiorespiratory fitness (CRF) was assessed in UK Biobank (UKB) using heart rate response to a submaximal ramped cycle ergometer test that was individualised for participant characteristics including cardiovascular disease risk. Studies have since explored health associations with CRF by estimating maximal oxygen consumption (VO2max) from UKB test data using interpretation methods that have not accounted for this individualisation procedure. Thus, dose-response relationships reported in these studies may be inaccurate. We developed and validated a novel VO2max estimation approach that accounts for the UKB test individualisation procedure and compared dose-response relationships with health outcomes between the novel and previous methods. Methods: In a cross-over study (n=189), participants completed several UKB tests and VO2max was measured. A multilevel modelling framework was developed that combines heart rate response features from the UKB test to estimate VO 2 max. Estimates were compared within participants across UKB test protocols, and with directly measured VO2max. Short-term test-retest reliability was assessed in a subsample of participants (n=87). In UKB, we examined associations between estimated CRF and disease endpoints (n=80,259) and compared associations obtained with an unvalidated method. Long-term test-retest reliability was examined (n=2877). Results: Estimated and directly measured VO2max were strongly correlated (Pearsons r range: 0.68 to 0.74) with no mean bias (women bias: -0.8 to 0.4; men bias range: -0.3 to 0.3), outperforming a previous approach for interpreting UKB test data. Agreement between estimated VO2max across different test protocols was strong (Pearsons r range: 0.94 to 0.99). Short- and long-term reliability was also high (lambda=0.91 and 0.80, respectively). All-cause mortality was 7 (95%CI 4-10%, 2686 deaths) lower and CVD mortality 9% (95%CI 3-14%, 858 deaths) lower for every 1-MET difference in fitness, associations twice as strong as determined by previous methods. Conclusions: We present a valid and reliable method for estimating CRF in UKB and demonstrate its utility in characterising dose-response relationships with health outcomes. Accounting for the individualisation procedure strengthens observed relationships between CRF and disease and enhances the case for promoting improved fitness in the general population.

Effects of Creatine Loading on Electromyographic Fatigue Threshold in Cycle Ergometry in College-Age Men

2008 ◽  
Vol 18 (2) ◽  
pp. 142-151 ◽  
Author(s):  
Ashley A. Walter ◽  
Abbie E. Smith ◽  
Trent J. Herda ◽  
Eric D. Ryan ◽  
Jordan R. Moon ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Cycle Ergometer ◽  
Fatigue Threshold ◽  
Double Blind Study ◽  
Double Blind ◽  
College Age ◽  
Cycle Ergometer Test ◽  
Before And After ◽  
The Right ◽  
Ergometer Test

The purpose of this study was to examine the effects of 5 d of creatine (Cr) loading on the electromyographic fatigue threshold (EMG FT) in college-age men. Sixteen men (age 22.4 ± 2.6 yr, height 177.4 ± 6.8 cm, weight 79.5 ± 10.6 kg; M ± SD) participated in this double-blind study and were randomly placed into either placebo (Pl; 10 g of flavored fructose powder per packet; n = 8) or Cr (5 g dicreatine citrate plus 10 g of flavored fructose powder per packet; n = 8) loading groups. Each participant ingested 1 packet 4 times/d, totaling 20 g/d for 5 days (loading). Before and after loading, each participant performed a discontinuous cycle-ergometer test to determine his EMG FT, using bipolar surface electrodes placed on the vastus lateralis of the right thigh. Four 60-s work bouts (ranging from 200 to 400 W) were completed. Adequate rest was given between bouts to allow for the participants’ heart rate (HR) to drop within 10 beats of their resting HR. The EMG amplitude was averaged over 5-s intervals for each 60-s work bout. Resulting slopes from each successive work bout were used to calculate EMG FT. A 2-way ANOVA, Group (Cr vs. Pl) EETime (pre vs. post), resulted in a nonsignificant (p > .05) interaction for supplement and time. In addition, a significant increase (p = .009) in weight was observed in the Cr group. These data suggest that there was a minimal influence of Cr loading on EMG FT for the participants in this study.

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