Metabolic adaptation to prolonged exercise

Factors influencing post-exercise proteinuria after marathon and ultramarathon races

Post-exercise proteinuria is one of the most common findings observed after short and intensive physical activity, but is observed also after long runs with low intensity. The aim of this study was to analyze factors influencing proteinuria after marathon runs. Two groups of male amateur runners were studied. The results of 20 marathon finishers (42.195 m), with a mean age of 49.3 ± 6.85 years; and 17 finishers of a 100-km ultramarathon with a mean age of 40.18±4.57 years were studied. Urine albumin to creatinine ratio (ACR) was calculated before and after both races. The relationship between ACR and run pace, metabolites (lactate, beta hydroxybutyrate), markers of inflammation (CRP, IL-6) and insulin was studied. The significant increase in ACR was observed after both marathon races. ACR increased from 6.41 to 21.96 mg/g after the marathon and from 5.37 to 49.64 mg/g after the ultramarathon (p<0.05). The increase in ACR was higher after the ultramarathon that after the marathon. There was no correlation between run pace and proteinuria. There was no correlation between ACR and glucose, free fatty acids, lactate, beta-hydroxybutyrate and insulin levels. There was significant negative correlation between ACR and interleukin 6 (IL-6) (r =-0.59, p< 0.05) after ultramarathon. Proteinuria is a common finding after physical exercise. After very long exercises it is related to duration but not to intensity. There is no association between metabolic and hormonal changes and ACR after marathon runs. The role on inflammatory cytokines in albuminuria is unclear.

Changes in salivary hormones, immunoglobulin A, and C-reactive protein in response to ultra-endurance exercises

The aim of the study was to determine the influence of the exercise duration on the changes in salivary stress markers in response to ultra-endurance exercises. The study was developed in 2 ultra-endurance exercise tests: the Ultra-trail Serra de Tramuntana (UTST), a 104 km ultra-marathon competition (n = 64) and the 25 km Cabrera Open Water Race (COWR) (n = 43). Participants in the COWR completed the 25 km at a constant pace of 3 km/h (3K group) or 2.5 km /h (2.5K group). Saliva samples were taken before and after the exercises. Salivary flow rate as well as cortisol, testosterone, C-reactive protein (CRP), and immunoglobulin A (IgA) levels were measured. Salivary flow rate decreased after the UTST but increased after the COWR. The UTST induced significant increases in cortisol and CRP levels and decreases in testosterone and IgA levels. Furthermore, a negative correlation was found between the time the athletes took to complete the exercise and the changes in salivary cortisol. After the COWR, higher increases in salivary cortisol levels were observed in the 3K group than in the 2.5K group. A significant effect of exercise decreasing testosterone and IgA levels was observed in both groups. No changes in the CRP levels were observed during the COWR. In conclusion, shorter times to complete the ultra-endurance exercise were associated with higher increases in cortisol. However, no relationships were found between the time to complete the exercises and the changes in testosterone, CRP, and IgA levels.

Elevated hair cortisol concentrations in endurance athletes

Engaging in intensive aerobic exercise, specifically endurance sports, is associated with HPA axis activation indicated by elevated cortisol levels. Whether the repeated short-term elevations in cortisol levels result in higher long-term cortisol exposure of endurance athletes has been difficult to examine since traditional methods of cortisol assessments (saliva, blood, urine) reflect only relatively short time periods. Hair segment analysis provides a new method to assess cumulative cortisol secretion over prolonged time periods in a retrospective fashion. The aim of this study was to investigate cumulative cortisol secretion over several months reflecting intensive training and competitive races by examining hair cortisol levels of endurance athletes. Hair samples were obtained from 304 amateur endurance athletes (long-distance runners, triathletes, cyclists) and 70 controls. Cortisol concentrations were determined in the first to third 3-cm hair segments most proximal to the scalp. In addition, self-report measures of training volume were obtained. Endurance athletes exhibited higher cortisol levels in all three hair segments compared to controls (p<.001). Positive correlations between the cortisol concentration in the first hair segment and each indicator of training volume were found (all p<.01). These data suggest that repeated physical stress of intensive training and competitive races among endurance athletes is associated with elevated cortisol exposure over prolonged periods of time. These findings may have important implications with regard to somatic and mental health of athletes which should be investigated in future research.

Changes in thioredoxin concentrations: an observation in an ultra-marathon race

OBJECTIVES

Changes in plasma thioredoxin (TRX) concentrations before, during, and after a 130-km endurance race were measured with the aim of elucidating the relationship between exercise and oxidative stress (OS).

METHODS

Blood samples were taken from 18 runners participating in a 2-day-long 130-km ultra-marathon during the 2 days of the race and for 1 week thereafter. There were six sampling time points: at baseline, after the goal had been reached on the first and second day of the endurance race, respectively, and on 1, 3, and 5/6 days post-endurance race. The samples were analyzed for plasma TRX concentrations, platelet count, and blood lipid profiles.

RESULTS

Concentrations of plasma TRX increased from 17.9 ± 1.2 ng/mL (mean ± standard error of the mean) at baseline to 57.3 ± 5.0 ng/mL after the first day's goal had been reached and to 70.1 ± 6.9 ng/mL after the second day's goal had been reached; it then returned to the baseline level 1 day after the race. Platelet counts of 21.3 ± 1.2 × 10(4) cell/μL at baseline increased to 23.9 ± 1.5 × 10(4) cells/μL on Day 1 and to 26.1 ± 1.0 × 10(4) cells/μL on Day 2. On Day 7, the platelet counts had fallen to 22.1 ± 1.2 × 10(4) cell/μL. There was a significant positive correlation between plasma TRX and platelet count.

CONCLUSIONS

These data suggest that plasma TRX is an OS marker during physical exercise. Further studies are needed to determine the appropriate level of exercise for the promotion of health.

Diagnostic Value of Proton MR Spectroscopy in Peripheral Arterial Occlusive Disease: A Prospective Evaluation

OBJECTIVE

The objective of the present study was to determine the detectability of metabolic alterations in patients with peripheral arterial occlusive disease (PAOD) using proton MR spectroscopy (hydrogen-1 MR spectroscopy).

SUBJECTS AND METHODS

Twenty-seven people were included in this study: 10 patients with PAOD and a pain-free walking distance of less than 200 m served as the patient group and 17 young healthy subjects served as a control group. Hydrogen-1 MR spectroscopy was performed on a 1.5-T scanner using an extremity coil and a point-resolved spectroscopy (PRESS) sequence (TR/TE, 1,500/30; 256 repetitions). For the patient group, a voxel was localized in the gastrocnemius muscle of the diseased leg. The data were processed using standard 1H MR spectroscopy tools. The identification of resonances detected on all MR spectra was made: intramyocellular lipids at 1.2 ppm, extramyocellular lipids at 1.6 ppm, lactate at 4.1 ppm, glucose with two main peaks at 3.4 and 3.8 ppm, choline at 3.2 ppm, and creatine at 3.0 and 3.9 ppm. To avoid operator bias, three spectral intensities were measured after correcting baseline and phase of MR spectra each time. The creatine signal was used as an internal reference; thus, all spectra were scaled relative to creatine. We compared the resultant intensity ratios between the two groups using the Mann-Whitney U test.

RESULTS

The lactate-creatine quotient was higher in the patient group, with a ratio of 1.6, than in the control group, with a ratio of 0.6. The glutamate-creatine ratio was higher in the patient group than in the control group (1.3 vs 0.8, respectively). All other ratios were higher in the control group. The best ratio for differentiating between healthy subjects and patients with PAOD was the glucose-lactate ratio. The patient group had a glucose-lactate quotient of 5.4, whereas the control group had a glucose-lactate quotient of 21.5 (p = 0.001).

CONCLUSION

Proton MR spectroscopy has the potential to allow identification of patients who have PAOD on the basis of altered muscle metabolism.

Role of proton MR for the study of muscle lipid metabolism

1H-MR spectroscopy (MRS) of intramyocellular lipids (IMCL) became particularly important when it was recognized that IMCL levels are related to insulin sensitivity. While this relation is rather complex and depends on the training status of the subjects, various other influences such as exercise and diet also influence IMCL concentrations. This may open insight into many metabolic interactions; however, it also requires careful planning of studies in order to control all these confounding influences. This review summarizes various historical, methodological, and practical aspects of 1H-MR spectroscopy (MRS) of muscular lipids. That includes a differentiation of bulk magnetic susceptibility effects and residual dipolar coupling that can both be observed in MRS of skeletal muscle, yet affecting different metabolites in a specific way. Fitting of the intra- (IMCL) and extramyocellular (EMCL) signals with complex line shapes and the transformation into absolute concentrations is discussed. Since the determination of IMCL in muscle groups with oblique fiber orientation or in obese subjects is still difficult, potential improvement with high-resolution spectroscopic imaging or at higher field strength is considered. Fat selective imaging is presented as a possible alternative to MRS and the potential of multinuclear MRS is discussed. 1H-MRS of muscle lipids allows non-invasive and repeated studies of muscle metabolism that lead to highly relevant findings in clinics and patho-physiology.

Effect of antioxidant vitamin treatment on the time course of hematological and hemorheological alterations after an exhausting exercise episode in human subjects

This study examined the effects of a 2-mo antioxidant vitamin treatment on acute hematological and hemorheological alterations induced by exhausting exercise; both sedentary and trained individuals were employed. Eighteen young male, human subjects (9 sedentary, 9 trained by regular exercise) participated in the study and performed an initial maximal aerobic cycle ergometer exercise with frequent blood sampling over a 24-h period and analysis of hematological and hemorheological parameters. All subjects were treated with an antioxidant vitamin A, C, and E regimen, supplemented orally for 2 mo, and then subjected to a second exercise test and blood sampling at the end of this period. In the sedentary group during the first testing period (before vitamin treatment), white blood cell counts and granulocyte percentages were increased at 2 h after the exercise test and remained elevated for 4-12 h. Red blood cell (RBC) deformability and aggregation were also altered by exercise in the sedentary group before vitamin treatment. However, none of these parameters in the sedentary group were altered by exercise after the 2-mo period of antioxidant vitamin treatment. With the exception of a transient rise in granulocyte percentage, these parameters were also not affected in the trained subjects before the vitamin treatment. Significant increases of RBC lipid peroxidation observed 12 h after the exercise test in both sedentary and trained subjects were also totally prevented by vitamin treatment. Our results indicate that antioxidant vitamin treatment is effective in preventing the inflammation-like response and coincident adverse hemorheological changes after an episode of exhausting exercise, and suggest that such changes may be related to exercise-induced death events.

Immuno-endocrine and metabolic responses to long distance ski racing in world-class male and female cross-country skiers

The purpose of this study was to characterize the extent of immune, endocrine, substrate and metabolic changes during a long-distance cross-country ski race in extremely well-trained athletes and evaluate if the blood perturbations would indicate signs of health risk. Ten male (M) and six female (F) national team skiers were investigated as they followed their usual routines of race preparations. Blood samples were drawn before and immediately after a World Cup 50-km M and 30-km F ski race with a mean finish time of 142 and 104 min, respectively. Hemoglobin, electrolytes, and C-reactive protein remained unchanged for both M and F. Serum testosterone remained unchanged in M, but doubled in F. Significant increases were observed in concentrations of granulocytes (F: 5 x, M: 5 x), natural killer cells (F: 2 x, M: 1.5 x), adrenaline (F: 12 x, M:10 x), noradrenaline (F: 7 x, M:5 x), growth hormone (F: 30 x, M: 2 x), cortisol (F: 1.5 x, M:2 x), glucose (F: 2 x, M:1.5 x), creatine kinase (F: 2 x, M:2 x), uric acid (F: 1.5 x, M: 1.5 x) and non-organic phosphate (F:2 x, M:2 x), while insulin concentration decreased (F: 0.5x, M: 0.8 x). Free fatty acid (FFA) concentration increased (F:2 x, M: 3 x). In conclusion, we observed substantial changes in several immuno-endocrine, substrate and metabolic measurements after long distance cross-country ski racing and suggest that some of these marked changes may reflect the large amount of muscle mass involved during skiing.

Intramuscular glycogen and intramyocellular lipid utilization during prolonged exercise and recovery in man: a 13C and 1H nuclear magnetic resonance spectroscopy study

Depletion of muscle glycogen is considered a limiting performance factor during prolonged exercise, whereas the role of the intramyocellular lipid (IMCL) pool is not yet fully understood. We examined 1) intramyocellular glycogen and lipid utilization during prolonged exercise, 2) resynthesis of muscle glycogen and lipids during recovery, and 3) changes in glycogen content between nonexercising and exercising muscles during recovery. Subjects ran on a treadmill at submaximal intensity until exhaustion. Glycogen concentrations were assessed in thigh, calf, and nonexercising forearm muscle, and IMCL content was measured in soleus muscle using magnetic resonance spectroscopy techniques. At the time of exhaustion, glycogen depletion was 2-fold greater in calf than in thigh muscles, but a significant amount of glycogen was left in both leg muscles. The glycogen concentration in nonexercising forearm muscle decreased during the initial 5 h of recovery to 73% of the baseline value. Duringthe exercise, the IMCL content decreased to 67% and subsequently during recovery increased to 83% of the baseline value. In summary, we found during prolonged running 1) significantly greater muscle glycogen utilization in the calf muscle group than in the thigh muscle group, 2) significant utilization of IMCL in the soleus muscle, and 3) a decrease in glycogen content in nonexercising muscle and an increase in glycogen content in recovering muscles during the postexercise phase. These latter data are consistent with the hypothesis that there is transfer of glycogen by the glucose-lactate and the glucose-->alanine cycle from the resting muscle (forearm) to recovering muscles (thigh and calf) after running exercise.

Hematological and biochemical changes during a short triathlon competition in novice triathletes

Short-course 'sprint' triathlons have become popular in recent years, often as a precursor to the longer full-course triathlons. We undertook a study investigating the haematological and biochemical changes that occur in novice triathletes between the start and finish and after each of the three legs of a short sprint triathlon involving swimming, cycling and running. The changes that occurred in the triathlon included a significant (P less than 0.003) decrease in weight from 71.7 kg, SD 7.9 to 70.3 kg, SD 7.6. Throughout the time span of the triathlon, the white blood cell count increased significantly (P less than 0.001), as did the platelet count (P less than 0.005) and plateletcrit (P less than 0.001). There were no significant changes during the period of the race in any of the other haematological variables measured. The biochemical variables measured were glucose, triglycerides, sodium, potassium, calcium, lactate dehydrogenase, creatinine and aspartate aminotransferase. Triglyceride, calcium and potassium values did not change between the pre- and post-race samplings. All other biochemical parameters showed a significant change (P less than 0.05 or better). Changes that occurred in the haematological and biochemical parameters between stages were many and varied. There was also a significant change in plasma volume during the swimming event (P less than 0.001), but this returned to normal during the later stages of the triathlon. In conclusion the changes that occurred during the triathlon were many and were similar to those reported elsewhere in the literature for longer events.(ABSTRACT TRUNCATED AT 250 WORDS)

Endogenous digoxin-like immunoreactivity in blood is increased during prolonged strenuous exercise

Digoxin-like immunoreactive factors (DLIFs) in serum may represent endogenous cardiotropic agents. We determined if blood levels of these endogenous factors changed during prolonged strenuous exercise. Total and loosely protein-bound (LPB) DLIF were measured by radioimmunoassay in the serum of nine healthy subjects during prolonged exercise to exhaustion. Mean total and LPB serum levels of DLIF increased by 72% (580 to 945 pg/mL) and 63% (53 to 91 pg/mL) over baseline values in digoxin equivalents (p less than 0.01), respectively, after three hours of exercise at 70% of VO2max. The prevalent serum nonesterified fatty acids (arachidonic, linoleic, oleic, palmitic, and stearic acids) as well as hydrocortisone did not account for the observed elevations in DLIF. Percent left ventricular fractional shortening (%FS) and mean velocity of left ventricular circumferential fiber shortening (mVCF) measured echocardiographically were lower (-18.0% and -16.4%, respectively, p less than 0.05) after exercise as compared to prior to exercise. Cardiac left ventricular dysfunction as measured by %FS did correlate with blood levels of DLIF (r = -0.680, p less than 0.02). These observations may suggest a relationship between serum levels of DLIF and cardiac fatigue.

Heart rate, metabolic and hormonal responses to maximal psycho-emotional and physical stress in motor car racing drivers

Motor car racing is representative of concentrative sporting activities, as well as instructive for mental-concentrative and psycho-emotional stress, which predominates with lower intensity, but longer duration in occupational work of today. A group of 20 car racing drivers was investigated both during car races (Formula Ford and Renault-5-Cup) and during progressive bicycle ergometry in the laboratory. Heart rate during car racing reached a mean level of 174.3 +/- 14.1 min-1 (mean +/- SD), corresponding to 90% of the maximal heart rate achieved at the end of exhaustive ergometry (n = 12). Catecholamine excretion in urine (adrenaline + noradrenaline) on average was 252.3 +/- 77.9 ng min-1 during car racing and 121.9 +/- 37.3 ng min-1 during exhaustive ergometry (n = 10). Most of the other metabolic parameters determined in blood (lactate, glucose, FFA = free fatty acids, plasma protein, insulin, HGH = human growth hormone) also showed significant differences between car racing and bicycle ergometry (n = 20). Therefore it is possible to distinguish between psychical and physical strain and the quantify their specific level. Especially blood lactate can be considered as a metabolic indicator of physical strain and FFA of psycho-emotional strain. Furthermore, significant negative correlations could be found between heart rate, FFA level, and catecholamine excretion during car racing and some measures of physical fitness determined on the bicycle ergometer (n = 12 or 10). This suggests a reduced cardiocirculatory and metabolic strain reaction in response to psychical stress situations with increased fitness. Moreover, HDL (high density lipoprotein) was found increased and oral glucose tolerance test was improved with elevated physical fitness (n = 20, respectively 16). From the results of this study it can be concluded that physical activity counteracts atherosclerosis and CHD (coronary heart disease), which are promoted by psycho-emotional and psycho-social stress.

Hormonal and metabolic response to three types of exercise of equal duration and external work output

Five normal men, aged 20-30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120-180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output Wmax = 600-900 W), continuous cycling at 50 rev X min-1 (II; Wmax = 100-150 W) and seven bouts of intermittent cycling at 70 rev X min-1 (III; Wmax = 300-450 W). Plasma cortisol, glucagon and lactate increased significantly (P less than 0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest VE, VO2, Wmax or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.

Metabolic, endocrine, and reproductive changes of a woman channel swimmer

We report the coordinated metabolic, hormonal, and reproductive data of a female channel swimmer during the pre-swim training period, immediately post-swim, and in the post-swim untrained state. Urine and blood samples collected at these times were assayed for diurnal urinary catecholamines, urinary C-peptide and 3-methylhistidine, total blood ketone bodies, glycerol, the reproductive hormones, adrenal androgens, and thyroid hormones. Subcutaneous fat was measured by ultrasonography. All of the metabolic and hormonal data post-swim except cortisol reflected the severe physiological stress. Urinary catecholamines returned to near-normal levels by 12 hours post-swim. The metabolic changes were associated with reproductive changes, including a shortened luteal phase, absence of ovulation, and increased LH secretion relative to FSH. The swimmer maintained high levels of body fat; she did not become amenorrheic. Metabolic and reproductive hormone levels returned to normal by 2 months post-swim.

Catecholamines, growth hormone, cortisol, insulin, and sex hormones in anaerobic and aerobic exercise

Seventeen male physical education students performed three types of treadmill exercise: (1) progressive exercise to exhaustion, (2) prolonged exercise of 50 min duration at the anaerobic threshold of 4 mmol . l-1 blood lactate (AE), (3) a single bout of short-term high-intensity exercise at 156% of maximal exercise capacity in the progressive test, leading to exhaustion within 1.5 min (ANE). Immediately before and after ANE and before, during, and after AE adrenaline, noradrenaline, growth hormone, cortisol, insulin, testosterone, and oestradiol were determined in venous blood, and glucose and lactate were determined in arterialized blood from the earlobe. Adrenaline and noradrenaline increased 15 fold during ANE and 3--4 fold and 6--9 fold respectively during AE. The adrenaline/noradrenaline ratio was 1 : 3 during ANE and 1 : 10 during AE. Cortisol increased by 35% in ANE (12% of which appeared in the postexercise period) and 54% in AE. Insulin increased during ANE but decreased during AE. Testosterone and oestradiol increased by 14% and 16% during ANE and by 22% and 28% during AE. The results point to a markedly higher emotional stress and higher sympatho-adrenal activity in anaerobic exercise. Growth hormone and cortisol appear to be the more affected by intense prolonged exercise. Taking plasma volume changes and changes of metabolic clearance rates into consideration, neither of the exercise tests appeared to affect secretion of testosterone and oestradiol.

Effects of prolonged warm-up exercise above and below anaerobic threshold on maximal performance

The purpose of the present study was to determine the effects of prolonged warm-up exercise above and below anaerobic threshold (AT) on maximal performance. Warm-up exercise consisted of pedalling the Monark cycle ergometer at either 40% (Below AT) or 68% (Above AT) of VO2max for 60 min. Each maximal performance consisted of two 40 s bouts of "all out" pedalling on the Monark cycle ergometer against 5.5 kg resistance separated by a 5 min rest period. These tests were administered on two occasions without warm-up exercise and were found to be reproducible for work output and peak blood lactate concentration. Below AT warm-up exercise significantly increased core temperature with no increase in steady state blood lactate concentration and was thus representative of a desired warmed-up status. This condition did not contribute to an improved maximal performance. Above AT warm-up exercise resulted in significant increases in core temperature and steady state blood lactate concentration. Work output and peak blood lactate concentration for maximal exercise were significantly decreased. It was concluded that task specific prolonged warm-up exercise below AT does not contribute to an improved maximal performance of the type employed in the present study. Following warm-up exercise above AT, maximal performance was impaired. This was attributed to probable glycogen depletion in fast twitch muscle fibers which in turn may have contributed to a decreased lactate production.

Blood metabolites during prolonged exercise in swimming and leg cycling

This study was designed to compare the influence of two modes of exercise (swimming and leg cycling) on the blood concentrations of metabolic substrates and metabolites during a 45-min exercise period. Eight college students (mean age = 21.6 +/- 1.2 year) exercised at 70% of VO2 max, in water using the front crawl on one occasion, and on a cycle ergometer using the legs on another. Blood samples were drawn at 0, 15, 30, and 45 min and analyzed for free fatty acids, glycerol, glucose, pyruvate, and lactate concentrations. Mean oxygen uptakes (2.23 vs 2.12 l . min-1) and heart rates (152 vs 150 b . min-1) for cycling and swimming respectively were not significantly different. Lactate and pyruvate were significantly (p less than 0.01) higher during swimming as compared to cycling. Free fatty acids, glycerol, and glucose were not significantly different between the two modes of exercise (p greater than 0.05). Assuming venous blood concentrations provide some indication of metabolic events, these data are compatible with a tendency to a higher relative carbohydrate oxidation rate during swimming as compared to cycling during prolonged exercise at the same relative work intensities.

Physiological and metabolic effects of a 25 km race in female athletes

Nine female athletes were examined before and after a 25 km race (German championship). Their average running speed was 3.89 m/s. Postexercise weight loss was 1.60 +/- 0.58 kg or 2.87% of body weight, the mean rectal temperature increased by 1.04 +/- 0.52 degrees C to 38.4 +/- 0.54 degrees C. Leucocytes, but no other blood parameters (hemoglobin, hematocrit, erythrocytes, MCV) showed a marked rise after the race. Blood lactate rose from 1.86 +/- 0.34 to 4.97 +/- 1.19 mmol/l but hypoglycemia was not present in any of the athletes at the end of exercise. After the run serum enzymes showed lower increases than those observed in men for the same exercise duration. Serum sodium, chloride and potassium showed similar increases, inorganic phosphate higher increments than found in men. The comparatively high rise in free glycerol suggested a marked mobilization of lipid substrate, whereas the increment in serum of free fatty acids was lower than in male subjects after similar athletic events. A lowering of neuromuscular excitability (m. vastus medialis quadricipitis) was found after the race but the changes were significant only for the fibers responding to longer durations of stimuli (0.3-30 ms).