Effects of endurance training on hyperammonaemia during a 45-min constant exercise intensity

1989 ◽  
Vol 59 (4) ◽  
pp. 268-272 ◽  
Author(s):  
C. Denis ◽  
M-T. Linossier ◽  
D. Dormois ◽  
M. Cottier-Perrin ◽  
A. Geyssant ◽  
...  
Keyword(s):  
Endurance Training ◽  
Exercise Intensity

Ten-day endurance training attenuates the hyperosmotic suppression of cutaneous vasodilation during exercise but not sweating

2005 ◽  
Vol 99 (1) ◽  
pp. 237-243 ◽  
Author(s):  
Takashi Ichinose ◽  
Kazunobu Okazaki ◽  
Shizue Masuki ◽  
Hiroyuki Mitono ◽  
Mian Chen ◽  
...  
Keyword(s):  
Endurance Training ◽  
Exercise Intensity ◽  
Plasma Osmolality ◽  
Young Male ◽  
Cycle Ergometer ◽  
Peak Oxygen Consumption ◽  
Cutaneous Vasodilation ◽  
Thermoregulatory Responses ◽  
Before And After ◽  
The Individual

It is well known that hyperosmolality suppresses thermoregulatory responses and that plasma osmolality (Posmol) increases with exercise intensity. We examined whether the decreased esophageal temperature thresholds for cutaneous vasodilation (THFVC) and sweating (THSR) after 10-day endurance training (ET) are caused by either attenuated increase in Posmol at a given exercise intensity or blunted sensitivity of hyperosmotic suppression. Nine young male volunteers exercised on a cycle ergometer at 60% peak oxygen consumption rate (V̇o2 peak) for 1 h/day for 10 days at 30°C. Before and after ET, thermoregulatory responses were measured during 20-min exercise at pretraining 70% V̇o2 peak in the same environment as during ET under isoosmotic or hyperosmotic conditions. Hyperosmolality by ∼10 mosmol/kgH2O was attained by acute hypertonic saline infusion. After ET, V̇o2 peak and blood volume (BV) both increased by ∼4% ( P < 0.05), followed by a decrease in THFVC ( P < 0.05) but not by that in THSR. Although there was no significant decrease in Posmol at the thresholds after ET, the sensitivity of increase in THFVC at a given increase in Posmol [ΔTHFVC/ΔPosmol,°C·(mosmol/kgH2O)−1], determined by hypertonic infusion, was reduced to 0.021 ± 0.005 from 0.039 ± 0.004 before ET ( P < 0.05). The individual reductions in ΔTHFVC/ΔPosmol after ET were highly correlated with their increases in BV around THFVC ( r = −0.89, P < 0.005). In contrast, there was no alteration in the sensitivity of the hyperosmotic suppression of sweating after ET. Thus the downward shift of THFVC after ET was partially explained by the blunted sensitivity to hyperosmolality, which occurred in proportion to the increase in BV.

Endurance training increases fatty acid turnover, but not fat oxidation, in young men

1999 ◽  
Vol 86 (6) ◽  
pp. 2097-2105 ◽  
Author(s):  
Anne L. Friedlander ◽  
Gretchen A. Casazza ◽  
Michael A. Horning ◽  
Anton Usaj ◽  
George A. Brooks
Keyword(s):  
Fatty Acid ◽  
Endurance Training ◽  
Exercise Intensity ◽  
Young Men ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Peak Oxygen Consumption ◽  
Whole Body ◽  
Plasma Ffa ◽  
Total Fat

We examined the effects of exercise intensity and a 10-wk cycle ergometer training program [5 days/wk, 1 h, 75% peak oxygen consumption (V˙o 2 peak)] on plasma free fatty acid (FFA) flux, total fat oxidation, and whole body lipolysis in healthy male subjects ( n= 10; age = 25.6 ± 1.0 yr). Two pretraining trials (45 and 65% ofV˙o 2 peak) and two posttraining trials (same absolute workload, 65% of oldV˙o 2 peak; and same relative workload, 65% of newV˙o 2 peak) were performed by using an infusion of [1-13C]palmitate and [1,1,2,3,3-2H]glycerol. An additional nine subjects (age 25.4 ± 0.8 yr) were treated similarly but were infused with [1,1,2,3,3-2H]glycerol and not [1-13C]palmitate. Subjects were studied postabsorptive for 90 min of rest and 1 h of cycling exercise. After training, subjects increasedV˙o 2 peak by 9.4 ± 1.4%. Pretraining, plasma FFA kinetics were inversely related to exercise intensity with rates of appearance (Ra) and disappearance (Rd) being significantly higher at 45 than at 65%V˙o 2 peak(Ra: 8.14 ± 1.28 vs. 6.64 ± 0.46, Rd: 8.03 ± 1.28 vs. 6.42 ± 0.41 mol ⋅ kg−1 ⋅ min−1) ( P ≤ 0.05). After training, when measured at the same absolute and relative intensities, FFA Ra increased to 8.84 ± 1.1, 8.44 ± 1.1 and Rd to 8.82 ± 1.1, 8.35 ± 1.1 mol ⋅ kg−1 ⋅ min−1, respectively ( P ≤ 0.05). Total fat oxidation determined from respiratory exchange ratio was elevated during exercise compared with rest, but did not differ among the four conditions. Glycerol Ra was elevated during exercise compared with rest but did not demonstrate significant intensity or training effects during exercise. Thus, in young men, plasma FFA flux is increased during exercise after endurance training, but total fat oxidation and whole-body lipolysis are unaffected when measured at the same absolute or relative exercise intensities.

Balance of carbohydrate and lipid utilization during exercise: the "crossover" concept

1994 ◽  
Vol 76 (6) ◽  
pp. 2253-2261 ◽  
Author(s):  
G. A. Brooks ◽  
J. Mercier
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Lipid Oxidation ◽  
Endurance Training ◽  
Exercise Intensity ◽  
Fiber Type ◽  
Moderate Intensity ◽  
Induced Responses ◽  
O2 Uptake ◽  
Sympathetic Nervous

The “crossover” concept represents a theoretical means by which one can understand the effects of exercise intensity and prior endurance training on the balance of carbohydrate (CHO) and lipid metabolism during sustained exercise. According to the crossover concept, endurance training results in muscular biochemical adaptations that enhance lipid oxidation as well as decrease the sympathetic nervous system responses to given submaximal exercise stresses. These adaptations promote lipid oxidation during mild- to moderate-intensity exercise. In contrast, increases in exercise intensity are conceived to increase contraction-induced muscle glycogenolysis, alter the pattern of fiber type recruitment, and increase sympathetic nervous system activity. Therefore the pattern of substrate utilization in an individual at any point in time depends on the interaction between exercise intensity-induced responses (which increase CHO utilization) and endurance training-induced responses (which promote lipid oxidation). The crossover point is the power output at which energy from CHO-derived fuels predominates over energy from lipids, with further increases in power eliciting a relative increment in CHO utilization and a decrement in lipid oxidation. The contemporary literature contains data indicating that, after endurance training, exercise at low intensities (< or = 45% maximal O2 uptake) is accomplished with lipid as the main substrate. In contrast, the literature also contains reports that are interpreted to indicate that during hard-intensity exercise (approximately 75% maximal O2 uptake) CHO is the predominant substrate. Seen within the context of the crossover concept these apparently divergent results are, in fact, consistent.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Lactate Diagnostics in Exercise Testing and Training

2011 ◽  
Vol 6 (1) ◽  
pp. 8-24 ◽  
Author(s):  
Ralph Beneke ◽  
Renate M. Leithäuser ◽  
Oliver Ochentel
Keyword(s):  
Endurance Training ◽  
Blood Lactate ◽  
Exercise Intensity ◽  
Aerobic Power ◽  
Lactate Concentration ◽  
Metabolic Energy ◽  
Moderate Intensity ◽  
Threshold Intensity ◽  
Work Intensity ◽  
Intensity Training

A link between lactate and muscular exercise was seen already more than 200 years ago. The blood lactate concentration (BLC) is sensitive to changes in exercise intensity and duration. Multiple BLC threshold concepts define different points on the BLC power curve during various tests with increasing power (INCP). The INCP test results are affected by the increase in power over time. The maximal lactate steady state (MLSS) is measured during a series of prolonged constant power (CP) tests. It detects the highest aerobic power without metabolic energy from continuing net lactate production, which is usually sustainable for 30 to 60 min. BLC threshold and MLSS power are highly correlated with the maximum aerobic power and athletic endurance performance. The idea that training at threshold intensity is particularly effective has no evidence. Three BLC-orientated intensity domains have been established: (1) training up to an intensity at which the BLC clearly exceeds resting BLC, light- and moderate-intensity training focusing on active regeneration or high-volume endurance training (Intensity < Threshold); (2) heavy endurance training at work rates up to MLSS intensity (Threshold ≤ Intensity ≤ MLSS); and (3) severe exercise intensity training between MLSS and maximum oxygen uptake intensity mostly organized as interval and tempo work (Intensity > MLSS). High-performance endurance athletes combining very high training volume with high aerobic power dedicate 70 to 90% of their training to intensity domain 1 (Intensity < Threshold) in order to keep glycogen homeostasis within sustainable limits.

scholarly journals Plasma BCAA concentrations during exercise of varied intensities in young healthy men—the impact of endurance training

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10491
Author(s):  
Anna Gawedzka ◽  
Marcin Grandys ◽  
Krzysztof Duda ◽  
Justyna Zapart-Bukowska ◽  
Jerzy A. Zoladz ◽  
...  
Keyword(s):  
Amino Acids ◽  
Endurance Training ◽  
Exercise Intensity ◽  
Energy Homeostasis ◽  
Lactate Concentration ◽  
Incremental Exercise ◽  
Moderate Intensity ◽  
Healthy Men ◽  
Before And After ◽  
The Impact

Background Branched-chain amino acids (BCAA) i.e., leucine (Leu), isoleucine (Ile) and valine (Val) are important amino acids, which metabolism play a role in maintaining system energy homeostasis at rest and during exercise. As recently shown lowering of circulating BCAA level improves insulin sensitivity and cardiac metabolic health. However, little is known concerning the impact of a single bout of incremental exercise and physical training on the changes in blood BCAA. The present study aimed to determine the impact of a gradually increasing exercise intensity—up to maximal oxygen uptake (VO2max) on the changes of the plasma BCAA [∑BCAA]pl, before and after 5-weeks of moderate-intensity endurance training (ET). Methods Ten healthy young, untrained men performed an incremental cycling exercise test up to exhaustion to reach VO2max, before and after ET. Results We have found that exercise of low-to-moderate intensity (up to ∼50% of VO2max lasting about 12 min) had no significant effect on the [∑BCAA]pl, however the exercise of higher intensity (above 70% of VO2max lasting about 10 min) resulted in a pronounced decrease (p < 0.05) in [∑BCAA]pl. The lowering of plasma BCAA when performing exercise of higher intensity was preceded by a significant increase in plasma lactate concentration, showing that a significant attenuation of BCAA during incremental exercise coincides with exercise-induced acceleration of glycogen utilization. In addition, endurance training, which significantly increased power generating capabilities at VO2max (p = 0.004) had no significant impact on the changes of [∑BCAA]pl during this incremental exercise. Conclusion We have concluded that an exercise of moderate intensity of relatively short duration generally has no effect on the [∑BCAA]pl in young, healthy men, whereas significant decrease in [∑BCAA]pl occurs when performing exercise in heavy-intensity domain. The impact of exercise intensity on the plasma BCAA concentration seems to be especially important for patients with cardiometabolic risk undertaken cardiac rehabilitation or recreational activity.

scholarly journals Gluconeogenesis and hepatic glycogenolysis during exercise at the lactate threshold

2013 ◽  
Vol 114 (3) ◽  
pp. 297-306 ◽  
Author(s):  
Chi-An W. Emhoff ◽  
Laurent A. Messonnier ◽  
Michael A. Horning ◽  
Jill A. Fattor ◽  
Thomas J. Carlson ◽  
...  
Keyword(s):  
Endurance Training ◽  
Exercise Intensity ◽  
Lactate Threshold ◽  
Lactate Concentration ◽  
Glucose Production ◽  
Constant Load ◽  
Metabolic Clearance ◽  
Trained Subjects ◽  
Relative Exercise Intensity ◽  
Constant Load Exercise

Because the maintenance of glycemia is essential during prolonged exercise, we examined the effects of endurance training, exercise intensity, and plasma lactate concentration ([lactate]) on gluconeogenesis (GNG) and hepatic glycogenolysis (GLY) in fasted men exercising at, and just below, the lactate threshold (LT), where GNG precursor lactate availability is high. Twelve healthy men (6 untrained, 6 trained) completed 60 min of constant-load exercise at power outputs corresponding to their individual LT. Trained subjects completed two additional 60-min sessions of constant-load exercise: one at 10% below the LT workload (LT-10%), and the other with a lactate clamp (LT-10%+LC) to match the [lactate] of the LT trial. Flux rates were determined by primed continuous infusion of [6,6-2H2]glucose, [3-13C]lactate, and [13C]bicarbonate tracers during 90 min of rest and 60 min of cycling. Exercise at LT corresponded to 67.6 ± 1.3 and 74.8 ± 1.7% peak O2 consumption in the untrained and trained subjects, respectively ( P < 0.05). Relative exercise intensity was matched between the untrained group at LT and the trained group at LT-10%, and [lactate] during exercise was matched in the LT and LT-10%+LC trials via exogenous lactate infusion. Glucose kinetics (rate of appearance, rate of disposal, and metabolic clearance rate) were augmented with the lactate clamp. GNG was decreased in the trained subjects exercising at LT and LT-10% compared with the untrained subjects, but increasing [lactate] in the LT-10%+LC trial significantly increased GNG (4.4 ± 0.9 mg·kg−1·min−1) compared with its corresponding control (1.7 ± 0.4 mg·kg−1·min−1, P < 0.05). Hepatic GLY was higher in the trained than untrained subjects, but not significantly different across conditions. We conclude that GNG plays an essential role in maintaining total glucose production during exercise in fasted men, regardless of training state. However, endurance training increases the ability to achieve a higher relative exercise intensity and absolute power output at the LT without a significant decrease in GNG. Furthermore, raising systemic precursor substrate availability increases GNG during exercise, but not at rest.

Pyruvate shuttling during rest and exercise before and after endurance training in men

2004 ◽  
Vol 97 (1) ◽  
pp. 317-325 ◽  
Author(s):  
Gregory C. Henderson ◽  
Michael A. Horning ◽  
Steven L. Lehman ◽  
Eugene E. Wolfel ◽  
Bryan C. Bergman ◽  
...  
Keyword(s):  
Endurance Training ◽  
Exercise Intensity ◽  
Glycolytic Flux ◽  
Arterial Lactate ◽  
Arterial Blood ◽  
Before And After ◽  
Isotopic Equilibration ◽  
Lactate And Pyruvate ◽  
Net Release ◽  
Rest And Exercise

We describe the isotopic exchange of lactate and pyruvate after arm vein infusion of [3-13C]lactate in men during rest and exercise. We tested the hypothesis that working muscle (limb net lactate and pyruvate exchange) is the source of the elevated systemic lactate-to-pyruvate concentration ratio (L/P) during exercise. We also hypothesized that the isotopic equilibration between lactate and pyruvate would decrease in arterial blood as glycolytic flux, as determined by relative exercise intensity, increased. Nine men were studied at rest and during exercise before and after 9 wk of endurance training. Although during exercise arterial pyruvate concentration decreased to below rest values ( P < 0.05), pyruvate net release from working muscle was as large as lactate net release under all exercise conditions. Exogenous (arterial) lactate was the predominant origin of pyruvate released from working muscle. With no significant effect of exercise intensity or training, arterial isotopic equilibration [(IEpyruvate/IElactate)·100%, where IE is isotopic enrichment] decreased significantly ( P < 0.05) from 60 ± 3.1% at rest to an average value of 12 ± 2.7% during exercise, and there were no changes in femoral venous isotopic equilibration. These data show that 1) the isotopic equilibration between lactate and pyruvate in arterial blood decreases significantly during exercise; 2) working muscle is not solely responsible for the decreased arterial isotopic equilibration or elevated arterial L/P occurring during exercise; 3) working muscle releases similar amounts of lactate and pyruvate, the predominant source of the latter being arterial lactate; 4) pyruvate clearance from blood occurs extensively outside of working muscle; and 5) working muscle also releases alanine, but alanine release is an order of magnitude smaller than lactate or pyruvate release. These results portray the complexity of metabolic integration among diverse tissue beds in vivo.

scholarly journals PO-207 Effect of exercise intensity and diet on Glucose Metabolic factors in T2DM rat skeletal muscle

2018 ◽  
Vol 1 (5) ◽  
Author(s):  
Lei Ji ◽  
He Long Quan ◽  
Chang Keun Kim ◽  
Chung Su Yoon
Keyword(s):  
Endurance Training ◽  
Exercise Intensity ◽  
High Fat Diet ◽  
Training Group ◽  
Normal Diet ◽  
High Fat ◽  
Low Intensity ◽  
Glut 4 ◽  
Muscle Groups ◽  
Intensity Of Exercise

Objective This study was to examine the effect of different exercise intensity and diet on the expression of the metabolism related factors in T2DM rat skeletal muscles. Methods Diet induced T2DM rat by a combination of low dose streptozotocin (STZ: 40mg/kg) and feeding of a high fat diet used as experimental animals. The rats trained on the treadmill for 8 weeks with low (40% max）and high (80% max) intensities of exercise on the treadmill for 8 weeks. The soleus (SOL) and extensor digitorum longus (EDL) muscles were excised. The western blotting was performed for the expression of AMPK, p-AMPK, PGC-1α，and GLUT-4 proteins. Results The expression of AMPK, p-AMPK, PGC-1α，and GLUT-4 proteins in SOL and EDL muscles were higher in both training groups compared to the non-training groups. The AMPK was differently expressed to the recruitment pattern of muscle group during exercise; expressed higher in SOL during low intensity of exercise and also highly expressed in EDL during high intensity of exercise, whereas the PGC-1a was expressed a contrast phenomenon to AMPK expression in both muscle groups. The expression of p-AMPK in both muscle groups was higher in low intensity of exercise and normal diet groups than in high intensity of exercise and high fat groups. The AMPK, p-AMPK, PGC-1α，and GLUT-4 protein expression demonstrated significantly higher in normal diet with endurance training group than in high fat diet with endurance training group.  Conclusions In summary, the expression of AMPK, p-AMPK, PGC-1α，and GLUT-4 proteins was differed with exercise intensities, diet and the type of muscles. These results indicated that the endurance training improved the insulin sensitivity according to the exercise intensity and diet in T2DM rats.

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