Effects of naloxone on maximal stress testing in females

1984 ◽  
Vol 56 (2) ◽  
pp. 436-440 ◽  
Author(s):  
R. G. McMurray ◽  
D. S. Sheps ◽  
D. M. Guinan
Keyword(s):  
Perceived Exertion ◽  
Exercise Duration ◽  
Time To Exhaustion ◽  
O2 Uptake ◽  
Ratings Of Perceived Exertion ◽  
Double Blind ◽  
Co2 Partial Pressure ◽  
End Tidal ◽  
End Tidal Co2 ◽  
Naloxone Treatment

To examine the effect of naloxone (an opiate antagonist) on exercise performance, six normal females (20–28 yr) walked on a treadmill (93.8 m/min) with the grade increasing 2.5% every 4 min until exhaustion. Each subject completed three trials: naloxone infusion (0.4 mg/ml saline), saline infusion (1 ml), and an infusion control. The order of trials was randomized and double blind. Each subject responded similarly at each submaximal stage for all three trials. The results during maximal exertion were different. Time to exhaustion was similar for all conditions, averaging 32.6 +/- 3.0 min with a maximal O2 uptake of 38.8 +/- 2.8 ml X kg-1 X min-1 and a lactate of 9.1 +/- 1.1 mmol/l. Maximal ventilation (BTPS) was 7.9 l/min less during the naloxone treatment when compared with either control or placebo trials (P less than 0.05). This difference was attributed to a 4-breath/min reduction in respiratory frequency (P less than 0.05). End-tidal CO2 partial pressure was approximately 4 Torr higher at maximum after naloxone injection. Maximal heart rates averaged 190.8 +/- 3.8 beats/min for both control and placebo trials. This was significantly greater (P less than 0.05) than the 185 +/- 2.4 beats/min recorded for the naloxone trials. Ratings of perceived exertion were 17.0 +/- 1.3 units at maximum, similar for all three trials. Despite these statistically significant cardiorespiratory differences, naloxone produced no effect on maximum O2 uptake or exercise duration.

Interaction of sleep state and chemical stimuli in sustaining rhythmic ventilation

1983 ◽  
Vol 55 (3) ◽  
pp. 813-822 ◽  
Author(s):  
J. B. Skatrud ◽  
J. A. Dempsey
Keyword(s):  
Periodic Breathing ◽  
Nrem Sleep ◽  
Normal Subjects ◽  
Positive Pressure ◽  
Sleep State ◽  
Co2 Partial Pressure ◽  
Apnea Duration ◽  
O2 Concentration ◽  
End Tidal ◽  
End Tidal Co2

The effect of sleep state on ventilatory rhythmicity following graded hypocapnia was determined in two normal subjects and one patient with a chronic tracheostomy. Passive positive-pressure hyperventilation (PHV) was performed for 3 min awake and during nonrapid-eye-movement (NREM) sleep with hyperoxia [fractional inspired O2 concentration (FIO2) = 0.50], normoxia and hypoxia (FIO2 = 0.12). During wakefulness, no immediate posthyperventilation apnea was noted following abrupt cessation of PHV in 27 of 28 trials [mean hyperventilation end-tidal CO2 partial pressure (PETCO2) 29 +/- 2 Torr, range 22-35]. During spontaneous breathing in hyperoxia, PETCO2 rose from 40.4 +/- 0.7 Torr awake to 43.2 +/- 1.4 Torr during NREM sleep. PHV during NREM sleep caused apnea when PETCO2 was reduced to 3-6 Torr below NREM sleep levels and 1-2 Torr below the waking level. In hypoxia, PETCO2 increased from 37.1 +/- 0.1 awake to 39.8 +/- 0.1 Torr during NREM sleep. PHV caused apnea when PETCO2 was reduced to levels 1-2 Torr below NREM sleep levels and 1-2 Torr above awake levels. Apnea duration (5-45 s) was significantly correlated to the magnitude of hypocapnia (range 27-41 Torr). PHV caused no apnea when isocapnia was maintained via increased inspired CO2. Prolonged hypoxia caused periodic breathing, and the abrupt transition from short-term hypoxic-induced hyperventilation to acute hyperoxia caused apnea during NREM sleep when PETCO2 was lowered to or below the subject's apneic threshold as predetermined (passively) by PHV. We concluded that effective ventilatory rhythmogenesis in the absence of stimuli associated with wakefulness is critically dependent on chemoreceptor stimulation secondary to PCO2-[H+].

An Exploratory Double-Blind Study of Caffeine Effects on Performance and Perceived Exertion in Judo

2019 ◽  
Vol 126 (3) ◽  
pp. 515-529
Author(s):  
Marina Saldanha da Silva Athayde ◽  
Rafael L. Kons ◽  
Daniele Detanico
Keyword(s):  
Perceived Exertion ◽  
Medium Effect ◽  
Double Blind Study ◽  
Ratings Of Perceived Exertion ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Male Athletes ◽  
Efficiency And Effectiveness ◽  
Judo Athletes ◽  
Low Sensitivity

This study analyzed the effects of caffeine ingestion during judo matches on judo athletes' match-derived performance and perceived exertion responses. We applied a double-blind randomized crossover (caffeine vs. placebo conditions) research design. Twelve male athletes performed three 5-minute matches separated by 15 minutes of passive rest. Immediately after each match, the athletes completed ratings of perceived exertion (RPEs), and one minute before beginning the second and third matches, they provided ratings of perceived recovery (RPRs). We filmed all matches for subsequent analysis of the athletes' technical skills. We found no interaction between condition and time of RPE, RPR, and match-derived technical variables, but number of attacks and RPR decreased over the matches, and RPE increased in both conditions. Three participants showed individual positive responses to caffeine ingestion for number of attacks. Attacks, efficiency, and effectiveness presented low sensitivity in both conditions, as only large changes could be identified. We conclude that caffeine ingestion did not provoke changes in either perceived exertion or match-derived performance. Match-derived technical variables were not sensitive for detecting small or medium effects of caffeine, but perceived exertion may detect at least medium effect after caffeine ingestion.

Diaphragm electrical activity during negative lower torso pressure in quadriplegic men

1981 ◽  
Vol 51 (3) ◽  
pp. 654-659 ◽  
Author(s):  
R. B. Banzett ◽  
G. F. Inbar ◽  
R. Brown ◽  
M. Goldman ◽  
A. Rossier ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Tidal Volume ◽  
Respiratory System ◽  
Afferent Pathways ◽  
Co2 Partial Pressure ◽  
Inspiratory Muscles ◽  
Spinal Lesions ◽  
Diaphragm Electrical Activity ◽  
End Tidal ◽  
End Tidal Co2

We recorded the diaphragm electromyogram (EMG) of quadriplegic men before and during exposure of the lower torso to continuous negative pressure, which caused shortening of the inspiratory muscles by expanding the respiratory system by one tidal volume. The moving-time-averaged diaphragm EMG was larger during expansion of the respiratory system. When we repeated the experiment with subjects who breathed through a mouthpiece, we found qualitatively similar EMG changes and little or no change in tidal volume or end-tidal CO2 partial pressure. When the pressure was applied or removed rapidly, changes in EMG occurred within one or two breaths. Because end-tidal CO2 partial pressure did not increase, and because the response was rapid, we suggest that the response results from proprioceptive, rather than chemoreceptive, reflexes. As most of these men had complete spinal lesions at C6 or C7 the afferent pathways are likely to be vagal or phrenic.

Effects of Caffeine Ingestion on Exercise-induced Change during High-Intensity Intermittent Exercise

1995 ◽  
Vol 5 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Isaiah Trice ◽  
Emily M. Haymes
Keyword(s):  
Blood Glucose ◽  
Perceived Exertion ◽  
Intermittent Exercise ◽  
Time To Exhaustion ◽  
Double Blind ◽  
Serum Free Fatty Acid ◽  
Caffeine Ingestion ◽  
Serum Free ◽  
Placebo Trial ◽  
Double Blind Design

In this study a double-blind design was used to determine the effect of caffeine on time to exhaustion and on associated metabolic and circulatory measures. Eight male subjects ingested either caffeine (5 mg/kg body weight) or a placebo 1 hr prior to exercise at 85-90% of maximum workload. Subjects were encouraged to complete three 30-min intermittent cycling periods at 70 rpm with 5 min rest between each. The exercise was terminated when the subject failed to complete three 30-min periods or failed to maintain 70 rpm for at least 15 s consecutively. Serum free fatty acids, glycerol, blood glucose, lactate, perceived exertion, heart rate, andcost were measured. The time to exhaustion was significantly longer during the caffeine trial than during the placebo trial. Serum free fatty acid levels were significantly different between trials. The decline in blood glucose levels was significantly less during the caffeine trial than during the placebo trial. There were no significant differences between trials for the other measures. It was concluded that caffeine increases time to exhaustion when trained subjects cycled intermittently at high levels of intensity.

Caffeine effects on VO2max test outcomes investigated by a placebo perceived-as-caffeine design

2017 ◽  
Vol 23 (4) ◽  
pp. 231-238 ◽  
Author(s):  
Cayque Brietzke ◽  
Ricardo Yukio Asano ◽  
Felipe De Russi de Lima ◽  
Fabiano Aparecido Pinheiro ◽  
Franco-Alvarenga ◽  
...  
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Perceived Exertion ◽  
Performance Outcomes ◽  
Peak Power Output ◽  
Time To Exhaustion ◽  
Ratings Of Perceived Exertion ◽  
Ergogenic Effects ◽  
Vo2max Test ◽  
Test Outcomes

Background: Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO2MAX) test outcomes. Aim: This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO2MAX, time to exhaustion and peak power output (WPEAK). Methods: Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO2 was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6–20 Borg scale) and maximal RPE was recorded for both overall (O-RPE14 and O-RPEMAX) and leg RPE (L-RPE14 and L-RPEMAX). Results: VO2MAX did not change significantly between MITs; however, CAF and PLA increased time to exhaustion (↑ ∼18.7% and ∼17.1%, respectively; p < .05) and WPEAK (↑ ∼13.0% and ∼11.8%, respectively; p < .05) when compared with control. When compared with control, CAF ingestion reduced submaximal and maximal overall and leg RPEs, the effect being greater in maximal (likely beneficial in O-RPEMAX and L-RPEMAX) than submaximal RPE (possibly beneficial in O-RPE14 and L-RPE14). Similar results were found when participants ingested PLA. Conclusions: Compared with control, CAF and PLA improved MIT performance outcomes such as time to exhaustion and WPEAK, without altering VO2MAX values. CAF effects were attributed to placebo.

Failure of Glycine-Arginine-α-Ketoisocaproic Acid to Improve High-Intensity Exercise Performance in Trained Cyclists

2011 ◽  
Vol 21 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Lukas Beis ◽  
Yaser Mohammad ◽  
Chris Easton ◽  
Yannis P. Pitsiladis
Keyword(s):  
Exercise Performance ◽  
High Intensity ◽  
Perceived Exertion ◽  
Cycle Ergometer ◽  
High Intensity Exercise ◽  
Ratings Of Perceived Exertion ◽  
Mean Power ◽  
Double Blind ◽  
Oral Supplementation ◽  
Experimental Trials

Oral supplementation with glycine-arginine-α-ketoisocaproic acid (GAKIC) has previously been shown to improve exhaustive high-intensity exercise performance. There are no controlled studies involving GAKIC supplementation in well-trained subjects. The aim of the current study was to examine the effects of GAKIC supplementation on fatigue during high-intensity, repeated cycle sprints in trained cyclists. After at least 2 familiarization trials, 10 well-trained male cyclists completed 2 supramaximal sprint tests each involving 10 sprints of 10 s separated by 50-s rest intervals on an electrically braked cycle ergometer. Subjects ingested 11.2 g of GAKIC or placebo (Pl) during a period of 45 min before the 2 experimental trials, administered in a randomized and double-blind fashion. Peak power declined from the 1st sprint (M ± SD; Pl 1,332 ± 307 W, GAKIC 1,367 ± 342 W) to the 10th sprint (Pl 1,091 ± 229 W, GAKIC 1,061 ± 272 W) and did not differ between conditions (p = .88). Mean power declined from the 1st sprint (Pl 892 ± 151 W, GAKIC 892 ± 153 W) to the 10th sprint (Pl 766 ± 120 W, GAKIC 752 ± 138 W) and did not differ between conditions (p = .96). The fatigue index remained at ~38% throughout the series of sprints and did not differ between conditions (p = .99). Heart rate and ratings of perceived exertion increased from the 1st sprint to the 10th sprint and did not differ between conditions (p = .11 and p = .83, respectively). In contrast to previous studies in untrained individuals, these results suggest that GAKIC has no ergogenic effect on repeated bouts of high-intensity exercise in trained individuals.

Perception of Effort during Constant Work to Self-Imposed Exhaustion

1979 ◽  
Vol 48 (3_suppl) ◽  
pp. 1111-1126 ◽  
Author(s):  
Donald H. Horstman ◽  
William P. Morgan ◽  
Allen Cymerman ◽  
James Stokes
Keyword(s):  
Perceived Exertion ◽  
Time To Exhaustion ◽  
Work Intensity ◽  
Ratings Of Perceived Exertion ◽  
Work Time ◽  
A Value ◽  
Perception Of Effort ◽  
Ventilatory Parameters ◽  
Effort Sense ◽  
High Work

The purpose of this study was to describe the pattern of change in effort sense and the value of this pattern in predicting work end-point at relatively high work intensity (80% V̇O2 max). The patterns of change of various physiological functions were also observed. Two modes of work (walking and running) were compared to ascertain generalizability of results. 26 healthy male volunteers served as subjects. Time to exhaustion (ET) did not differ between walking and running. As work continued during both tasks, significant increases of V̇E, V̇E/V̇O2, V̇E/V̇CO2 and HR and a significant decrease of ET were observed; while V̇O2 and R remained fairly constant. V̇O2 and V̇E during the run were about 5% greater than during the walk; there were no differences in other measures. Ratings of perceived exertion (RPE) from the Borg Scale were identical for both conditions, increasing in a near linear fashion from a value of 12.9 at 25% of total work time to 18.9 at exhaustion. Ratings obtained at 25 and 50% ET were extrapolated to time of exhaustion; the point of intercept corresponded to ratings of perceived exertion for maximal work. At exhaustion, subjects rated perception of respiratory exertion for the walk as less than that for the run; perception of leg exertion was not different for the two conditions. Plasma lactate, epinephrine and norepinephrine concentrations following exercise did not differ between the two conditions. The findings for the walking experiment were essentially replicated in a second investigation involving another 28 subjects. It is concluded that, with the exception of V̇O2 and some ventilatory parameters, walking and running ar the same relative work intensity resulted in comparable perceptual and physiological responses. Psychophysical judgments made early during work were reasonably accurate predictors of exhaustion time.

The Effects of Choline Supplementation on Physical Performance

2000 ◽  
Vol 10 (2) ◽  
pp. 170-181 ◽  
Author(s):  
John P. Warber ◽  
John F. Patton ◽  
William J. Tharion ◽  
Steven H. Zeisel ◽  
Robert P. Mello ◽  
...  
Keyword(s):  
Physical Performance ◽  
Perceived Exertion ◽  
Performance Measure ◽  
Load Carriage ◽  
Strenuous Exercise ◽  
Time To Exhaustion ◽  
Double Blind ◽  
Total Load ◽  
And Performance ◽  
Heavy Loads

It has been reported that plasma choline levels decrease following certain types of strenuous exercise. Preliminary findings also suggest that a drop in plasma choline may limit physical performance, while choline supplementation may delay fatigue during prolonged efforts. A double-blind crossover design was used to determine the relationship between plasma choline and performance during and after 4 hr of strenuous exercise. Volunteers (N = 14) received either a placebo or treatment beverage (8.425 g choline citrate) prior to and midway through a 4-hr load carriage treadmill exercise (3% grade at 5.6 km/h × 20 km) carrying a total load of 34.1 kg. Following the treadmill test, run time-to-exhaustion and squat tests were performed, and perceived exertion, plasma choline, glycerophosphocholine, and phosphatidylcholine were measured. Plasma choline levels increased 128% after the run-to-exhaustion with the choline supplemented beverage but remained unchanged with the placebo beverage. No significant effects were seen with choline supplementation on any outcome performance measure. Consequently, soldiers conditioned to carry heavy loads over long distances do not deplete plasma choline as a result of a prolonged exhaustive exercise under a placebo beverage, nor do they benefit from choline supplementation to delay fatigue under the same conditions.

METABOREFLEX CHANGES RELATIONSHIP BETWEEN END-TIDAL CO2 PARTIAL PRESSURE AND VENTILATION

2003 ◽  
Vol 35 (Supplement 1) ◽  
pp. S229
Author(s):  
N Hayashi ◽  
T Miyamoto ◽  
Y Fukuba ◽  
T Yoshida
Keyword(s):  
Partial Pressure ◽  
Co2 Partial Pressure ◽  
End Tidal ◽  
End Tidal Co2

Effect of aerosolized histamine on occlusion pressure and ventilation in humans

1982 ◽  
Vol 53 (3) ◽  
pp. 690-697 ◽  
Author(s):  
R. P. Millman ◽  
D. A. Silage ◽  
D. D. Peterson ◽  
A. I. Pack
Keyword(s):  
Smooth Muscle ◽  
Neural Activity ◽  
Occlusion Pressure ◽  
Bronchial Smooth Muscle ◽  
Co2 Partial Pressure ◽  
Residual Capacity ◽  
End Tidal ◽  
End Tidal Co2 ◽  
Airway Conductance ◽  
Stimulation Of

To define further the mechanism by which inspiratory neural activity is increased in asthma, we studied the effect of aerosolized histamine on occlusion pressure (P100) and ventilation in conscious humans while end-tidal CO2 partial pressure was maintained at a constant, slightly hypercapnic level. The dose of histamine we employed varied from subject to subject but was such that it produced a 70% reduction in specific airway conductance in each subject. In 9 of the 13 subjects tested, inhaled histamine significantly increased P100. This increase was not due to changes in functional residual capacity, which was not affected by aerosolized histamine. Inhalation of isoproterenol abolished the effects of histamine on specific airway conductance and P100. Anesthesia of the airways by lidocaine eliminated the effect of histamine on P100 but did not alter the magnitude of the change in specific airway conductance produced by histamine. We conclude that the increase in occlusion pressure seen after the inhalation of histamine in humans depends on both contraction of bronchial smooth muscle and stimulation of airway receptors.

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