Metabolic, catecholamine, and endurance responses to caffeine during intense exercise

1996 ◽  
Vol 81 (4) ◽  
pp. 1658-1663 ◽  
Author(s):  
M. Jackman ◽  
P. Wendling ◽  
D. Friars ◽  
T. E. Graham
Keyword(s):  
Muscle Glycogen ◽  
Venous Blood ◽  
Lactate Concentration ◽  
Muscle Metabolism ◽  
Intense Exercise ◽  
Muscle Lactate ◽  
Caffeine Ingestion ◽  
Norepinephrine Concentration ◽  
Before And After ◽  
Exercise Period

Jackman, M., P. Wendling, D. Friars, and T. E. Graham.Metabolic, catecholamine, and endurance responses to caffeine during intense exercise. J. Appl. Physiol. 81(4): 1658–1663, 1996.—This study examined the possible effects of caffeine ingestion on muscle metabolism and endurance during brief intense exercise. We tested 14 subjects after they ingested placebo or caffeine (6 mg/kg) with an exercise protocol in which they cycled for 2 min, rested 6 min, cycled 2 min, rested 6 min, and then cycled to voluntary exhaustion. In each exercise the intensity required the subject’s maximal O2 consumption. Eight subjects had muscle and venous blood samples taken before and after each exercise period. The caffeine ingestion resulted in a significant increase in endurance (4.12 ± 0.36 and 4.93 ± 0.60 min for placebo and caffeine, respectively) and resulted in a significant increase in plasma epinephrine concentration throughout the protocol but not in norepinephrine concentration. During the first two exercise bouts, the power and work output were not different; blood lactate concentrations were not affected significantly by caffeine ingestion, but during the exercise bouts muscle lactate concentration was significantly increased by caffeine. The net decrease in muscle glycogen was not different between treatments at any point in the protocol, and even at the time of fatigue there was at least 50% of the original glycogen concentration remaining. The data demonstrated that caffeine ingestion can be an effective ergogenic aid for exercise that is as brief as 4–6 min. However, the mechanism is not associated with muscle glycogen sparing. It is possible that caffeine is exerting actions directly on the active muscle and/or the neural processes that are involved in the activity.

Skeletal muscle metabolism during exercise is influenced by heat acclimation

1985 ◽  
Vol 59 (6) ◽  
pp. 1929-1935 ◽  
Author(s):  
A. J. Young ◽  
M. N. Sawka ◽  
L. Levine ◽  
B. S. Cadarette ◽  
K. B. Pandolf
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Rate ◽  
Muscle Glycogen ◽  
Muscle Metabolism ◽  
Heat Acclimation ◽  
Plasma Lactate ◽  
Muscle Lactate ◽  
Lactate Accumulation ◽  
Hot Environment ◽  
Before And After

The influence of heat acclimation on skeletal muscle metabolism during submaximal exercise was studied in 13 healthy men. The subjects performed 30 min of cycle exercise (70% of individual maximal O2 uptake) in a cool [21 degrees C, 30% relative humidity (rh)] and a hot (49 degrees C, 20% rh) environment before and again after they were heat acclimated. Aerobic metabolic rate was lower (0.1 l X min-1; P less than 0.01) during exercise in the heat compared with the cool both before and after heat acclimation. Muscle and plasma lactate accumulation with exercise was greater (P less than 0.01) in the hot relative to the cool environment both before and after acclimation. Acclimation lowered (P less than 0.01) aerobic metabolic rate as well as muscle and plasma lactate accumulation in both environments. The amount of muscle glycogen utilized during exercise in the hot environment did not differ from that in the cool either before or after acclimation. These findings indicate that accumulation of muscle lactate is increased and aerobic metabolic rate is decreased during exercise in the heat before and after heat acclimation; increased muscle glycogen utilization does not account for the increased muscle lactate accumulation during exercise under extreme heat stress; and heat acclimation lowers the aerobic metabolic rate and muscle and blood lactate accumulation during exercise in a cool as well as a hot environment.

Active skeletal muscle metabolism and tension production: the influence of biopsies

1993 ◽  
Vol 71 (3-4) ◽  
pp. 241-246 ◽  
Author(s):  
T. E. Graham ◽  
B. Wolfe ◽  
J. K. Barclay
Keyword(s):  
Muscle Glycogen ◽  
Lactate Concentration ◽  
Muscle Metabolism ◽  
Force Output ◽  
Muscle Lactate ◽  
Tension Development ◽  
Control Series ◽  
Minimal Impact ◽  
Lactate Release ◽  
Over Time

The influence of repeated sampling by the biopsy technique on skeletal muscle's metabolic and force-output responses was studied using the in situ canine gastrocnemius preparation. The left muscle was stimulated (8 V, 0.2 ms) for 1 h at 3 Hz. In the biopsy series (n = 9) muscle samples were taken at rest, and at 0.5, 2, 5, 15, 30, 45, and 60 min of stimulation. In the control series (n = 8) the left and right muscles were quick-frozen in N2 immediately after the 60 min of stimulation. The two series were not different in blood flow, [Formula: see text], arterial or venous [H+], muscle glycogen, or lactate release throughout the 60 min of activity. The lactate release was transient and was associated with an accumulation of intramuscular lactate and a period of rapid glycogenolysis. The biopsy series had a modest but significantly (p < 0.05) higher muscle lactate concentration both at rest and at the end of the contractions. The biopsy series also had less (p < 0.05) tension development throughout the hour; however, the O2 cost per unit of tension development was not different between groups, nor was the rate of tension decline over time different. This together with the similarities in perfusion, carbohydrate use, and lactate metabolism suggests that repeated biopsies had minimal impact on the muscle. The technique allows the collection of data over time; this improves the detail of experiments and means that fewer animals are required for a study.Key words: glycolysis, lactate, hydrogen ion, fatigue, muscle glycogen.

Costal diaphragmatic O2 and lactate extraction in laryngeal hemiplegic ponies during exercise

1988 ◽  
Vol 65 (4) ◽  
pp. 1723-1728 ◽  
Author(s):  
M. Manohar ◽  
T. E. Goetz ◽  
D. Nganwa
Keyword(s):  
Maximal Exercise ◽  
Venous Blood ◽  
Lactate Concentration ◽  
Lactate Production ◽  
Hemoglobin Concentration ◽  
Insignificant Change ◽  
Resistive Breathing ◽  
O2 Extraction ◽  
Before And After ◽  
Arterial Po2

Diaphragmatic O2 and lactate extraction were examined in seven healthy ponies during maximal exercise (ME) carried out without, as well as with, inspiratory resistive breathing. Arterial and diaphragmatic venous blood were sampled simultaneously at rest and at 30-s intervals during the 4 min of ME. Experiments were carried out before and after left laryngeal hemiplegia (LH) was produced. During ME, normal ponies exhibited hypocapnia, hemoconcentration, and a decrease in arterial PO2 (PaO2) with insignificant change in O2 saturation. In LH ponies, PaO2 and O2 saturation decreased well below that in normal ponies, but because of higher hemoglobin concentration, arterial O2 content exceeded that in normal ponies. Because of their high PaCO2 during ME, acidosis was more pronounced in LH animals despite similar lactate values. Diaphragmatic venous PO2 and O2 saturation decreased with ME to 15.5 +/- 0.9 Torr and 18 +/- 0.5%, respectively, at 120 s of exercise in normal ponies. In LH ponies, corresponding values were significantly less: 12.4 +/- 1.3 Torr and 15.5 +/- 0.7% at 120 s and 9.8 +/- 1.4 Torr and 14.3 +/- 0.6% at 240 s of ME. Mean phrenic O2 extraction plateaued at 81 and 83% in normal and LH animals, respectively. Significant differences in lactate concentration between arterial and phrenic-venous blood were not observed during ME. It is concluded that PO2 and O2 saturation in the phrenic-venous blood of normal ponies do not reach their lowest possible values even during ME. Also, the healthy equine diaphragm, even with the added stress of inspiratory resistive breathing, did not engage in net lactate production.

Effect of carbohydrate ingestion on exercise metabolism

1988 ◽  
Vol 65 (4) ◽  
pp. 1553-1555 ◽  
Author(s):  
M. Hargreaves ◽  
C. A. Briggs
Keyword(s):  
Muscle Glycogen ◽  
Venous Blood ◽  
Cycle Ergometer ◽  
Strenuous Exercise ◽  
Carbohydrate Ingestion ◽  
Ergometer Exercise ◽  
Glucose Polymer ◽  
Before And After ◽  
Plasma Insulin Levels ◽  
Glycogen Utilization

Five male cyclists were studied during 2 h of cycle ergometer exercise (70% VO2 max) on two occasions to examine the effect of carbohydrate ingestion on muscle glycogen utilization. In the experimental trial (CHO) subjects ingested 250 ml of a glucose polymer solution containing 30 g of carbohydrate at 0, 30, 60, and 90 min of exercise; in the control trial (CON) they received an equal volume of a sweet placebo. No differences between trials were seen in O2 uptake or heart rate during exercise. Venous blood glucose was similar before exercise in both trials, but, on average, was higher during exercise in CHO [5.2 +/- 0.2 (SE) mmol/l] compared with CON (4.8 +/- 0.1, P less than 0.05). Plasma insulin levels were similar in both trials. Muscle glycogen levels were also similar in CHO and CON both before and after exercise; accordingly, there was no difference between trials in the amount of glycogen used during the 2 h of exercise (CHO = 62.8 +/- 10.1 mmol/kg wet wt, CON = 56.9 +/- 10.1). The results of this study indicate that carbohydrate ingestion does not influence the utilization of muscle glycogen during prolonged strenuous exercise.

Agreement between i-STAT and YSI 2300 devices to determine lactate concentrations in dogs undergoing exercise

2016 ◽  
Vol 12 (2) ◽  
pp. 75-82 ◽  
Author(s):  
C. Berkman ◽  
M.C. Pereira ◽  
K.B. Nardi ◽  
G.T. Pereira ◽  
O.A.B. Soares ◽  
...  
Keyword(s):  
Venous Blood ◽  
Lactate Concentration ◽  
Intense Exercise ◽  
Blood Samples ◽  
Handheld Device ◽  
Clinical Evaluations ◽  
Small Constant ◽  
Constant Bias ◽  
Highly Correlated ◽  
The Relationship

Little information is available comparing the i-STAT and the YSI 2300 Stat Plus devices to determine the lactate concentration [Lac] in dogs undergoing intense exercise. The reproducibility of the YSI 2300 for quantifying the [Lac] in canine blood [Lac]b and plasma [Lac]p samples has been observed. In addition, the i-STAT handheld device was used to quantify [Lac] in dogs subjected to exercise, and the results were compared with that of YSI 2300. Venous blood samples of Beagle and American Pit Bull Terrier dogs were obtained during an intense exercise training on a treadmill. [Lac]p and [Lac]b were quantified using the YSI 2300 instrument to determine the reproducibility of the results. A total of 52 specimens were compared for both plasma and whole blood. For comparing the devices (YSI 2300 vs i-STAT), 96 samples were used. Ordinary least products regression, the correlation coefficient, and Bland-Altman plots were used to assess the agreement of using the i-STAT device. The relationship between duplicate measurements of both [Lac]b and [Lac]p by YSI 2300 was strong (r=0.99). A correlation between the data obtained using the i-STAT and YSI 2300 instruments was observed for both the [Lac]p (r=0.97) and [Lac]b (r=0.88). The i-STAT exhibited a small constant bias (-0.25 mmol/l) compared to YSI 2300 ([Lac]b). There were proportional biases of 0.89 mmol/l for [Lac]p and 1.22 mmol/l for [Lac]b when using YSI 2300 vs i-STAT. We confirmed the reproducibility of the YSI 2300 for canine lactate blood/plasma samples. The results obtained by the i-STAT and YSI 2300 analyser were highly correlated, but a small constant bias was observed between them. The i-STAT device can be used in clinical evaluations, and it is also adequate for designing and monitoring fitness programmes.

scholarly journals Reviewing the Effect of 10 Days of Intense Exercise Period on Certain Blood Parameters of Tennis Players

2018 ◽  
Vol 6 (11) ◽  
pp. 95
Author(s):  
Muzaffer Selcuk ◽  
Vedat Cinar ◽  
Mucahit Sarikaya ◽  
Salih Oner
Keyword(s):  
Statistical Significance ◽  
Exercise Program ◽  
Blood Parameters ◽  
Intense Exercise ◽  
Negative Effects ◽  
Blood Samples ◽  
Tennis Players ◽  
Before And After ◽  
Exercise Period ◽  
Competition Period

This study aims to observe the possible negative effects that might occur on bio-chemistry and hemogram values of tennis players during the intense competition period by comparing the blood values of pre-competition period with 10 days of intense exercise. Blood samples were obtained from tennis team players who do not have any specific health problems and who study in university and regularly exercise. Mean age of the athletes are 22,40 ± 3,20 years and mean height is 179,83 ± 7,57 cm. This study is performed with 14 volunteer tennis players. Blood samples are obtained during the first day of the intense exercise program after the exercise, last day of the exercises and also right after the exercises. As per the obtained data, descriptive statistics are run (mean and standard deviation) and in order to compare the values of before and after the 10 days of intense exercise, Wilcoxon two related sample test was used. As per the results of the blood tests from before and after the exercise period, it is seen that values such as AST, ALT, MCH, MCHC and CK showed statistical significance (P<0.05). The athletes who prepared for the competitions with these values showed positive increases in bio-chemistry and hemogram values.

Lactate as substrate for glycogen resynthesis after exercise

1987 ◽  
Vol 62 (6) ◽  
pp. 2237-2240 ◽  
Author(s):  
R. W. Stevenson ◽  
D. R. Mitchell ◽  
G. K. Hendrick ◽  
R. Rainey ◽  
A. D. Cherrington ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Recovery Period ◽  
Control Level ◽  
Lactate Concentration ◽  
Perfusion Medium ◽  
Muscle Lactate ◽  
Arterial Lactate ◽  
Medium Flow ◽  
Flow Through ◽  
Lactate Levels

Muscle glycogen levels in the perfused rat hemicorpus preparation were reduced two-thirds by electrical stimulation plus exposure to epinephrine (10(-7) M) for 30 min. During the contraction period muscle lactate concentrations increased from a control level of 3.6 +/- 0.6 to a final value of 24.1 +/- 1.6 mumol/g muscle. To determine whether the lactate that had accumulated in muscle during contraction could be used to resynthesize glycogen, glycogen levels were determined after 1–3 h of recovery from the contraction period during which time the perfusion medium (flow-through system) contained low (1.3 mmol/l) or high (10.5 or 18 mmol/l) lactate concentrations but no glucose. With the low perfusate lactate concentration, muscle lactate levels declined to 7.2 +/- 0.8 mumol/g muscle by 3 h after the contraction period and muscle glycogen levels did not increase (1.28 +/- 0.07 at 3 h vs. 1.35 +/- 0.09 mg glucosyl U/g at end of exercise). Lactate disappearance from muscle was accounted for entirely by output into the venous effluent. With the high perfusate lactate concentrations, muscle lactate levels remained high (13.7 +/- 1.7 and 19.3 +/- 2.0 mumol/g) and glycogen levels increased by 1.11 and 0.86 mg glucosyl U/g, respectively, after 1 h of recovery from exercise. No more glycogen was synthesized when the recovery period was extended. Therefore, it appears that limited resynthesis of glycogen from lactate can occur after the contraction period but only when arterial lactate concentrations are high; otherwise the lactate that builds up in muscle during contraction will diffuse into the bloodstream.

Plasma catecholamines and their effect on blood lactate and muscle lactate output

1984 ◽  
Vol 57 (2) ◽  
pp. 321-325 ◽  
Author(s):  
W. N. Stainsby ◽  
C. Sumners ◽  
G. M. Andrew
Keyword(s):  
Venous Blood ◽  
Plasma Catecholamines ◽  
Muscle Group ◽  
O2 Uptake ◽  
Plantaris Muscle ◽  
Muscle Lactate ◽  
Blood Samples ◽  
Lactate Output ◽  
Before And After

This study was designed to test the hypothesis that epinephrine (E) and norepinephrine (NE) increase net muscle lactate output (L) of in situ gastrocnemius-plantaris muscle group during contractions. Plasma [E] and [NE] were measured before and after the surgical isolation of the muscle and at 10-min intervals during the 60-min experiments. Plasma [E] and [NE] were increased threefold by intravenous infusions of E (n = 3) or NE (n = 3) at a rate of 1.5 micrograms X kg body wt-1 X min-1. Arterial and muscle venous blood samples for O2 and lactate concentrations were also obtained. The infusions began at min 11 and repetitive isometric contractions (4 tw/s) began at min 31. The presurgery plasma [E] and [NE] averaged 0.34 and 0.52 ng/ml, respectively, and rose to 1.12 and 1.19 ng/ml 10 min after surgery. Arterial and venous lactate concentrations (CaL and CvL) increased continuously during E infusion but remained constant during NE infusion. Maximal L during the first 10 min of contractions was significantly increased compared with an identical earlier study without infusions. O2 uptake was not changed by the infusions. It is concluded that E causes CaL to rise and that both E and NE increase maximal net lactate output during contractions.

Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men

2001 ◽  
Vol 91 (1) ◽  
pp. 249-257 ◽  
Author(s):  
J. Smorawiński ◽  
K. Nazar ◽  
H. Kaciuba-Uscilko ◽  
E. Kamińska ◽  
G. Cybulski ◽  
...  
Keyword(s):  
Lactate Concentration ◽  
Human Growth ◽  
Plasma Renin ◽  
Bed Rest ◽  
Peak Oxygen Uptake ◽  
Endurance Athletes ◽  
Norepinephrine Concentration ◽  
Before And After ◽  
Response To Exercise ◽  
Sedentary Subjects

To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (V˙o 2 peak) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in V˙o 2 peak correlated positively with the initial values ( r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60%V˙o 2 peak ( P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

Effect of pH on Muscle Glycolysis during Exercise

1981 ◽  
Vol 61 (3) ◽  
pp. 331-338 ◽  
Author(s):  
J. R. Sutton ◽  
N. L. Jones ◽  
C. J. Toews
Keyword(s):  
Venous Blood ◽  
Lactate Concentration ◽  
Cycle Ergometer ◽  
Plasma Lactate ◽  
Glycogen Depletion ◽  
Vo2 Max ◽  
Muscle Lactate ◽  
Blood Ph ◽  
Plasma Lactate Concentration ◽  
Control Study

1. Five males were studied on three occasions, after oral administration of CaCO3 (control), NH4Cl (acidosis) and NaHCO3 (alkalosis), in a dose of 0.3 g/kg, taken over a 3 h period at rest. The subjects then exercised on a cycle ergometer for 20 min at 33% maximal oxygen uptake (Vo2 max.), followed by 20 min at 66% and at 95% Vo2 max. until exhaustion. 2. Endurance at 95% Vo2 max. was longest with alkalosis (5.44 ± 1.05 min), shortest with acidosis (3.13 ± 0.97 min) and intermediate in the control study (4.56 ± 1.31 min); venous blood pH at exhaustion was 7.33 ± 0.02 (mean ±1 sem), 7.13 ± 0.02 and 7.26 ± 0.02 respectively. 3. Concentrations of plasma lactate at exhaustion were 7.10 ± 0.8 mmol/l 4.0 ± 0.5 and 7.9 ± 0.9 mmol/l in the control, acidosis and alkalosis studies respectively. 4. Muscle lactate increased most from rest to exhaustion with alkalosis to 17.1 ± 2.5 μmol/g and least with acidosis to 12.2 ± 1.4 μmol/g. Muscle glycogen depletion was comparable in control and alkalosis studies. 5. The lower plasma lactate concentration during exercise in acidosis compared with control and alkalosis appears to be due to an inhibition of muscle glycolysis combined with a reduction in lactate efflux from muscle.

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