Effect of graded epinephrine infusion on blood lactate response to exercise

1995 ◽  
Vol 79 (4) ◽  
pp. 1206-1211 ◽  
Author(s):  
M. J. Turner ◽  
E. T. Howley ◽  
H. Tanaka ◽  
M. Ashraf ◽  
D. R. Bassett ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Blood Lactate ◽  
Random Order ◽  
Peak Oxygen Uptake ◽  
Sudden Increase ◽  
Control Test ◽  
Epinephrine Infusion ◽  
Exercise Tests ◽  
Ergometer Exercise ◽  
Graded Exercise

In an attempt to determine whether the lactate threshold (LT) is the result of a sudden increase in plasma epinephrine (Epi), eight healthy college-aged males (22.4 +/- 0.4 yr) were recruited to perform three cycle ergometer exercise tests. Each subject performed a graded exercise test (GXT) to determine LT, Epi threshold, and norepinephrine threshold (64.6 +/- 2.4, 62.5 +/- 2.4, and 60.8 +/- 4.3% peak oxygen uptake, respectively). Each subject also completed, in random order, two 30-min submaximal (20% peak oxygen uptake below LT) exercise tests. During one test, graded Epi infusions were carried out at rates of 0.02–0.12 micrograms.kg-1.min-1; the other served as a control test. Infusion resulted in plasma Epi concentrations similar to those observed during GXT. The increase in blood lactate with Epi infusion was significantly greater than that during the control test (3.0 +/- 0.3 vs. 1.4 +/- 0.1 mmol/l at minute 30) but did not approach levels exhibited during GXT. We suggest an interaction of the increasing plasma Epi with other factors may be responsible for the sudden increase in blood lactate during graded exercise.

Physiological Responses to Specific Maximal Exercise Tests for Cross-Country Skiing

1993 ◽  
Vol 18 (4) ◽  
pp. 359-365 ◽  
Author(s):  
Phillip B. Watts ◽  
Jon Eric Sulentic ◽  
Kip M. Drobish ◽  
Timothy P. Gibbons ◽  
Victoria S. Newbury ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Blood Lactate ◽  
Maximal Exercise ◽  
Physiological Responses ◽  
Peak Oxygen Uptake ◽  
Open Circuit ◽  
Exercise Tests ◽  
Double Poling ◽  
Cross Country

The present study attempted to quantify differences in peak physiological responses to pole-striding (PS), double poling on roller skis (DP), and diagonal striding on roller skis (DS) during maximal exercise. Six expert cross-country ski racers (3 M, 3 F) with a mean age of 20.2 ± 1.3 yrs served as subjects. Testing was conducted on a motorized ski treadmill with a tracked belt surface. Expired air was analyzed continuously via an automated open-circuit system and averaged each 20 s. Heart rate was monitored via telemetry and arterialized blood was collected within 1 min of test termination and analyzed immediately for lactate. Peak values for heart rate and blood lactate did not differ among techniques. Peak oxygen uptake was higher for PS and DS versus DP whereas no difference was found between PS and DS. The VO2 peak for DP was 77 and 81% of VO2 peak for PS and DS, respectively. It was concluded that despite similar peak heart rate and blood lactate values, DP elicits a lower VO2 peak than DS or PS and that PS responses appear to closely reflect those of DS. Key words: exercise testing, maximum oxygen uptake, roller skiing, specificity of exercise, x-c skiing

Mechanism of the exercise hyperkalemia: an alternate hypothesis

1997 ◽  
Vol 83 (2) ◽  
pp. 631-643 ◽  
Author(s):  
Karlman Wasserman ◽  
William W. Stringer ◽  
Richard Casaburi ◽  
Yong-Yu Zhang
Keyword(s):  
Oxygen Uptake ◽  
Femoral Vein ◽  
Early Period ◽  
Peak Oxygen Uptake ◽  
Cycle Ergometer ◽  
Exercise Tests ◽  
Early Exercise ◽  
Major Mechanism ◽  
Alternate Hypothesis ◽  
Ergometer Exercise

Wasserman, Karlman, William W. Stringer, Richard Casaburi, and Yong-Yu Zhang. Mechanism of the exercise hyperkalemia: an alternate hypothesis. J. Appl. Physiol. 83(2): 631–643, 1997.—A progressive hyperkalemia is observed as exercise intensity increases. The current most popular hypothesis for the hyperkalemia is that the Na+-K+pump cannot keep pace with the K+efflux from muscle during the depolarization-repolarization process of the sarcolemmal membrane during muscle contraction. In this report, we present data that suggest an alternate hypothesis to those previously described. Because phosphocreatine (PCr) is a highly dissociated acid and creatine is neutral at cell pH, the concentration of nondiffusible anions decreases, and an alkaline reaction takes place when PCr hydrolyzes. This creates a state of cation (K+) excess and H+ depletion in the cell. To examine the balance of K+ and H+ for exercising muscle during the early period of exercise when PCr changes most rapidly, catheters were inserted into the brachial artery and femoral vein (FV) in five healthy subjects who performed two 6-min cycle ergometer exercise tests at 40 and 85% of peak oxygen uptake. FV blood was sampled every 5 s during the first 2 min, then every 30 s for the remaining 4 min of exercise and the first 3 min of recovery, and then less frequently for the next 12 min. Arterial sampling was every 30 s during exercise and simultaneous with FV sampling during recovery. Arterial K+ concentration ([K+]) increase lagged FV [K+] increase. The hyperkalemia observed during early exercise results from K+ release from skeletal muscle. FV [K+] increased by 5 s of the start of exercise and followed the rate of H+ loss from the FV blood for the first 30 s of exercise. FV lactate and Na+ kinetics differed from K+ kinetics during exercise and recovery. As predicted from the PCr hydrolysis reaction, the exercising limb took up H+ and released K+ at the start of exercise (first 30 s) at both exercise intensities, resulting in a FV metabolic alkalosis. K+ release was essentially complete by 3 min, the time at which oxygen uptake (and, presumably, PCr) reached its asymptote. These findings lead us to hypothesize that the early K+release by the cell takes place with H+ exchange and that the major mechanism for the exercise hyperkalemia is the reduction in nondiffusible intracellular anions in the myocyte as PCr hydrolyzes.

Threshold for muscle lactate accumulation during progressive exercise

1989 ◽  
Vol 66 (6) ◽  
pp. 2710-2716 ◽  
Author(s):  
J. Chwalbinska-Moneta ◽  
R. A. Robergs ◽  
D. L. Costill ◽  
W. J. Fink
Keyword(s):  
Blood Lactate ◽  
Bicycle Ergometer ◽  
Exercise Tests ◽  
Muscle Lactate ◽  
Lactate Accumulation ◽  
Ergometer Exercise ◽  
Progressive Exercise ◽  
Blood Lactate Accumulation ◽  
Highly Correlated ◽  
The Relationship

The purpose of this study was to investigate the relationship between muscle and blood lactate concentrations during progressive exercise. Seven endurance-trained male college students performed three incremental bicycle ergometer exercise tests. The first two tests (tests I and II) were identical and consisted of 3-min stage durations with 2-min rest intervals and increased by 50-W increments until exhaustion. During these tests, blood was sampled from a hyperemized earlobe for lactate and pH measurement (and from an antecubital vein during test I), and the exercise intensities corresponding to the lactate threshold (LT), individual anaerobic threshold (IAT), and onset of blood lactate accumulation (OBLA) were determined. The test III was performed at predetermined work loads (50 W below OBLA, at OBLA, and 50 W above OBLA), with the same stage and rest interval durations of tests I and II. Muscle biopsies for lactate and pH determination were taken at rest and immediately after the completion of the three exercise intensities. Blood samples were drawn simultaneously with each biopsy. Muscle lactate concentrations increased abruptly at exercise intensities greater than the “below-OBLA” stage [50.5% maximal O2 uptake (VO2 max)] and resembled a threshold. An increase in blood lactate and [H+] also occurred at the below-OBLA stage; however, no significant change in muscle [H+] was observed. Muscle lactate concentrations were highly correlated to blood lactate (r = 0.91), and muscle-to-blood lactate ratios at below-OBLA, at-OBLA, and above-OBLA stages were 0.74, 0.63, 0.96, and 0.95, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Footstrike is the major cause of hemolysis during running

2003 ◽  
Vol 94 (1) ◽  
pp. 38-42 ◽  
Author(s):  
R. D. Telford ◽  
G. J. Sly ◽  
A. G. Hahn ◽  
R. B. Cunningham ◽  
C. Bryant ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Random Order ◽  
Peak Oxygen Uptake ◽  
Red Cell ◽  
Free Hemoglobin ◽  
Serum Haptoglobin ◽  
Total Hemoglobin ◽  
Exercise Induced

There is a wide body of literature reporting red cell hemolysis as occurring after various forms of exercise. Whereas the trauma associated with footstrike is thought to be the major cause of hemolysis after running, its significance compared with hemolysis that results from other circulatory stresses on the red blood cell has not been thoroughly addressed. To investigate the significance of footstrike, we measured the degree of hemolysis after 1 h of running. To control for the potential effects of oxidative and circulatory stresses on the red blood cell, the same subjects cycled for 1 h at equivalent oxygen uptake. Our subjects were 10 male triathletes, who each completed two separate 1-h sessions of running and cycling at 75% peak oxygen uptake, which were performed in random order 1 wk apart. Plasma free hemoglobin and serum haptoglobin concentrations were measured as indicators of hemolysis. We also measured methemoglobin as a percentage of total hemoglobin immediately postexercise as an indicator of red cell oxidative stress. Plasma free hemoglobin increased after both running ( P < 0.01) and cycling ( P < 0.01), but the increase was fourfold greater after running ( P < 0.01). This was reflected by a significant fall in haptoglobin 1 h after the running trials, whereas no significant changes occurred after cycling at any sample point. Methemoglobin increased twofold after both running and cycling ( P < 0.01), with no significant differences between modes of exercise. The present data indicate that, whereas general circulatory trauma to the red blood cells associated with 1 h of exercise at 75% maximal oxygen uptake may result in some exercise-induced hemolysis, footstrike is the major contributor to hemolysis during running.

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.

A perceptually regulated, graded exercise test predicts peak oxygen uptake during treadmill exercise in active and sedentary participants

2012 ◽  
Vol 112 (10) ◽  
pp. 3459-3468 ◽  
Author(s):  
Roger Eston ◽  
Harrison Evans ◽  
James Faulkner ◽  
Danielle Lambrick ◽  
Harran Al-Rahamneh ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Exercise Test ◽  
Treadmill Exercise ◽  
Peak Oxygen Uptake ◽  
Graded Exercise Test ◽  
Graded Exercise

Prediction of peak oxygen uptake from sub-maximal ratings of perceived exertion elicited during a graded exercise test in obese women

2009 ◽  
Vol 46 (6) ◽  
pp. 1150-1153 ◽  
Author(s):  
Jeremy B. J. Coquart ◽  
Christine Lemaire ◽  
Alain-Eric Dubart ◽  
Claire Douillard ◽  
David-Pol Luttenbacher ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Exercise Test ◽  
Perceived Exertion ◽  
Peak Oxygen Uptake ◽  
Obese Women ◽  
Ratings Of Perceived Exertion ◽  
Graded Exercise Test ◽  
Graded Exercise

Intratest reliability and test–retest reproducibility of the oxygen uptake efficiency slope in healthy participants

2009 ◽  
Vol 16 (4) ◽  
pp. 493-498 ◽  
Author(s):  
Christophe Van Laethem ◽  
Johan De Sutter ◽  
Wim Peersman ◽  
Patrick Calders
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Minute Ventilation ◽  
Exercise Duration ◽  
Peak Oxygen Uptake ◽  
Exercise Tests ◽  
Uptake Efficiency ◽  
Carbon Dioxide Output ◽  
Oxygen Uptake Efficiency Slope ◽  
Healthy Participants

Background The oxygen uptake efficiency slope (OUES) is a newer ventilatory exercise parameter, used in the evaluation of healthy participants and patients with cardiovascular disease. However, few data about the reliability and reproducibility of OUES are available. Our study assessed intratest reliability and test-retest reproducibility of OUES in healthy participants. Design and methods Eighteen participants (age 28 ± 6 years, BMI 22.1 ± 1.9 kg/m2, 10 men) performed two identical maximal exercise tests on a bicycle ergometer. To assess test-retest reproducibility, we performed Bland-Altman analysis and calculated the coefficient of repeatability of the main ventilatory variables. Results OUES remained stable during the second part of the exercise test. Mean values varied 2.4 ± 4.0% between OUES calculated at 70% (OUES70) and at 100% of exercise duration. Mean variation decreased to 1.4 ± 2.3% when OUES was calculated at 90% of exercise duration (OUES90). The Bland-Altman 95% limits of agreement for OUES90 were +3 and –6%, those for OUES70 were +11 and –8%. The coefficient of repeatability for OUES was 597 ml/min or 18.7% of the average value of repeated OUES measurements. These results were similar to those of peak oxygen uptake and minute ventilation/carbon dioxide output. However, the test-retest reproducibility for submaximal-derived values of OUES was lower, as we noted higher coefficients of repeatability for OUES90 and OUES70, increasing up to 27% of the average of repeated values. Conclusion OUES shows excellent intratest reliability and has a test-retest reproducibility that is similar to that of peak oxygen uptake and minute ventilation/carbon dioxide output slope. However, its reproducibility becomes higher when it is calculated from increasing levels of achieved exercise intensity.

The validity of predicting maximal oxygen uptake from perceptually regulated graded exercise tests of different durations

2006 ◽  
Vol 97 (5) ◽  
pp. 535-541 ◽  
Author(s):  
Roger G. Eston ◽  
James A. Faulkner ◽  
Elizabeth A. Mason ◽  
Gaynor Parfitt
Keyword(s):  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Exercise Tests ◽  
Graded Exercise

The metabolic response to treadmill graded exercise: traditional vs. underwater

2012 ◽  
Vol 8 (1) ◽  
pp. 11-18
Author(s):  
P. Watson ◽  
C. Mendonca ◽  
R.A. Lehnhard ◽  
S. Tu ◽  
S.A. Butterfield ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Repeated Measures ◽  
Metabolic Response ◽  
Metabolic Stress ◽  
Maximum Speed ◽  
Exercise Tests ◽  
Bruce Protocol ◽  
Graded Exercise ◽  
Blood Lactate Accumulation ◽  
Post Hoc

The purpose of this study was to determine the metabolic effect(s) of four graded exercise tests (GXT) performed on the underwater treadmill (UWT), and compare them to the results from performing the standard Bruce protocol on a traditional land treadmill (LT). Twelve male Division I college athletes performed the stand Bruce protocol on a LT and 4 different GXT protocols on the UWT. Each test was performed to volitional max. oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER) and blood lactate (BL), which were measured at regular intervals throughout each of the GXTs. A two-way ANOVA with repeated measures was used to determine any main effect among the variables within the protocols and within the stages. Established effects were identified further using Tukey's post-hoc analysis. VO2 and HR were positively correlated in all the GXTs, (r=0.992−0.999). When comparing the UWT GXTs to the Bruce, significant (P≤0.001) differences were found within certain stages for each of the dependent variables. While the Bruce resulted in attainment of VO2max, (mean = 55.72±5.92 ml/kg/min), only one of the UWT GXTs resulted in the same level of metabolic stress. At maximum speed and water velocity, the UWT produced a mean VO2 of 53.9±3.68 ml/kg/min. HR and RER both increased by stage in all the GXTs as did BL. The onset of blood lactate accumulation (OBLA) was identified in all of the GXTs with the exception of one of the UWTs. Mean BL at OBLA ranged from, 3.12+1.31 to 5.98+4.24 mmol/dl. Our results suggest that an UWT GXT protocol can be developed that would produce metabolic results similar to the Bruce through stage 5. Buoyancy and variation in biomechanics need to be studied further for their effects on energy metabolism while performing work on the UWT. However, this study provides a better understanding of the metabolic demands at different treadmill speeds and water jet settings with the UWT.

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