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)     

Plasma renin activity, aldosterone and catecholamine levels when swimming and running

The purpose of this study was to determine the response of plasma renin activity (PRA), plasma aldosterone concentration (PAC) and catecholamines to two graded exercises differing by posture. Seven male subjects (19-25 years) performed successively a running rest on a treadmill and a swimming test in a 50-m swimming pool. Each exercise was increased in severity in 5-min steps with intervals of 1 min. Oxygen consumption, heart rate and blood lactate, measured every 5 min, showed a similar progression in energy expenditure until exhaustion, but there was a shorter time to exhaustion in the last step of the running test. PRA, PAC and catecholamines were increased after both types of exercise. The PRA increase was higher after the running test (20.9 ng AngI X ml-1 X h-1) than after swimming (8.66 ng AngI X ml-1 X h-1). The PAC increase was slightly greater after running (123 pg X ml-1) than swimming (102 pg X ml-1), buth the difference was not significant. Plasma catecholamine was higher after the swimming test. These results suggest that the volume shift induced by the supine position and water pressure during swimming decreased the PRA response. The association after swimming compared to running of a decreased PRA and an enhanced catecholamine response rule out a strict dependence of renin release under the effect of plasma catecholamines and is evidence of the major role of neural pathways for renin secretion during physical exercise.     

Plasma free and sulphated catecholamines after ultra-long exercise and recovery

We investigated the early and late effects of two types of ultra-long exercise on sympatho-adrenal and dopaminergic activity. With this aim both free and sulphoconjugated plasma catecholamines (CA), noradrenaline (NA), adrenaline (A), and dopamine (DA) were determined in two groups of athletes immediately after completion of 24-h running or a 10-h triathlon and on recovery during the next 1-3 days. Both races stimulated the sympathetic activity, but differences were observed in the CA pattern: the 24-h run induced a marked elevation of free and sulphoconjugated NA (+175% and +180%, respectively) but failed to alter significantly A and DA levels. The triathlon challenge increased the three conjugated CA (NA sulphate +350%; A sulphate +110%; DA sulphate +270%) and to a lesser extent free CA (NA +45%; A +30%). On the first post-exercise morning, a sustained intense noradrenergic activity was still present in the 24 h-runners, as evidenced by the large increase in free and sulphated NA levels (+140% and +100%, respectively). Such a prolonged activity was also indicated after completion of the triathlon, by the increase of NA sulphate (+140%) observed on the 1st recovery day. However, after the triathlon there was a decreased release of A from the adrenal medulla for several days. These data show that both types of ultralong exercise are able to induce for several hours a sustained sympathetic activation during the test and in the recovery period. Furthermore, the study shows that plasma conjugated CA may provide delayed and cumulative indexes of sympathetic activation, complementary to the instantaneous markers such as free CA.     

Effect of low blood glucose on plasma CRF, ACTH, and cortisol during prolonged physical exercise.

The effects of low blood glucose concentration during low-intensity prolonged physical exercise on the hypothalamus-pituitary-adrenocortical axis were investigated in healthy young men. In experiment 1, six subjects who had fasted for 14 h performed bicycle exercise at 50% of their maximal O2 uptake until exhaustion. At the end of the exercise, adrenocorticotropic hormone (ACTH) and cortisol increased significantly. However, this hormonal response was totally abolished when the same subjects exercised at the same intensity while blood glucose concentrations were maintained at the preexercise level. In experiment 2, in addition to ACTH and cortisol, the possible changes in plasma concentration of corticotropin-releasing factor (CRF) were investigated during exercise of the same intensity performed by six subjects. As suggested by a previous study (Tabata et al. Clin. Physiol. Oxf. 4: 299-307, 1984), when the blood glucose concentrations decreased to less than 3.3 mM, plasma concentrations of CRF, ACTH, and cortisol showed a significant increase. At exhaustion, further increases were observed in plasma CRF, ACTH, and cortisol concentrations. These results demonstrate that decreases in blood glucose concentration trigger the pituitary-adrenocortical axis to enhance secretion of ACTH and cortisol during low-intensity prolonged exercise in humans. The data also might suggest that this activation is due to increased concentration of CRF, which was shown to increase when blood glucose concentration decreased to a critical level of 3.3 mM.     

A biorhythmologic approach to evaluating forced swimming as an experimental model of a "depressive" state

Rhythmical structure of forced swimming was studied on rats. Reserpine (1 mg/kg, 24 h before testing), clonidine (150 mkg/kg) and prolonged repeated striatal stimulation induced behavioural depression with reorganization of swimming rhythm and increase of short cycles (less than 6 s) of immobility. After chronic administration of antidepressants (imipramine, amitriptyline, niamid, 10 mg/kg/day, during 14 days), on the contrary, the number of these cycles diminished, while the number of active swimming cycles increased. Chrono-biological "index of depression" is suggested to express more exactly behavioural depression and specific activity of antidepressants than usual registration of immobility time.     

Responses of atrial natriuretic peptide and other fluid regulating hormones to long distance swimming in the sea

The plasma hormonal response following a swimming competition in the sea (18 km) was evaluated in 12 top level male endurance swimmers. At the end of the effort, while plasma renin activity (PRA) and aldosterone concentration (ALDO) were unchanged, a significant increase in plasma atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) concentrations were recorded. These changes were associated with a decrease in haematocrit and an increase in Na⁺ and Cl^– plasma concentrations. The individual variations of ANP (difference between the final and initial concentrations) were inversely correlated with the corresponding individual variations of PRA and ADH. The results suggest that, during prolonged swimming, ANP may exert an inhibitory effect on the PRA-ALDO axis and have a modulatory role with regard to ADH secretion.     

不同剂量玛咖对力竭运动致大鼠运动性低血糖的保护作用

目的：探讨不同剂量玛咖对力竭运动致大鼠运动性低血糖的保护作用。方法：采用递增负荷力竭游泳训练的方法建立运动性低血糖动物模型。55只42 d龄雄性Wistar大鼠随机分为5组：①静止对照组（C组）,②运动对照组（M组）,③~⑤运动+低、中、高剂量玛咖组（LM I、LM Ⅱ,LM Ⅲ组）,每组10只（剔除不符合实验要求的大鼠5只）。每天灌胃（ig）1次,LM各组灌胃玛咖的剂量为0.2,0.4,1.2 g/kg体重,灌胃体积为5 ml/kg体重,C、M组灌胃等体积生理盐水。运动大鼠采用递增负荷力竭游泳训练42 d,42 d力竭游泳训练后,测定体重、力竭游泳时间,取血、肝脏及深层股四头肌检测相关生化指标。结果：与C组比较,M组体重、血糖水平、肌糖原与肝糖原含量、肝细胞磷酸烯醇式丙酮酸羧激酶（phosphoenol pyruvate carboxy kinase,PEPCK）表达、肝细胞阳性染色累计吸光度均值等均明显降低（P<0.05或P<0.01）;力竭游泳时间无明显差异;血乳酸含量明显升高（P<0.01）。与M组比较,LM各组体重、血糖水平、肌糖原与肝糖原含量、肝细胞PEPCK表达、肝细胞阳性染色累计吸光度均值等均明显升高（P<0.05或P<0.01）,力竭游泳时间明显延长（P<0.01）,血乳酸含量明显降低（P<0.01）。与LM I组比较,LMⅢ组体重无明显差异,LM Ⅲ组血糖水平、肌糖原与肝糖原含量、肝细胞PEPCK表达、肝细胞阳性染色累计吸光度均值等均明显升高（P<0.05）,力竭游泳时间明显延长,血乳酸含量明显降低（P<0.05）。结论：高剂量玛咖可有效抑制和延缓长时间、大负荷运动导致的运动性低血糖和运动性疲劳的发生与发展,其机制可能与优化肌糖原和肝糖原的储备量及上调糖异生限速酶PEPCK的表达,提高PEPCK活性,促进糖异生有关。     

Daily hyperhydration effect on electrolyte deficiency of endurance-Trained subjects during prolonged hypokinesia

The aim of this study was to evaluate the effect of a daily intake of fluid and salt supplementation (FSS) on the deficiency of electrolytes, which is characterized by higher rather than lower plasma concentration of electrolytes during prolonged hypokinesia (HK) (decreased number of km taken per day). Forty long distance runners aged 22–25 yr with a peak V0₂ 65.4 mL min^-1 kg^-1 with an average 14.2 km d running distance were selected as subjects. They were equally divided into four groups: 1) unsupplemented control subjects (UCS); 2) unsupplemented hypokinetic subjects (UHS); 3) supplemented hypokinetic subjects (SHS), and 4) supplemented control subjects (SCS). During the investigation of 364 d, groups 2 and 3 maintained an average running distance of less than 4.7 km per day, groups 1 and 4 did not experience any modification in their normal training routines and diets. During the preexperimental period of 60 d and during the experimental period of 364 d urinary excretion of electrolytes and concentrations of sodium, potassium, calcium, and magnesium in plasma were determined. Whole blood hemoglobin, hematocrit index, plasma osmolality, and plasma protein concentration were measured. In the UHS plasma concentration of electrolytes and urinary excretion thereof, fluid elimination, hematocrit, whole blood hemoglobin, plasma osmolality, and plasma protein concentration increased significantly (p < 0.05) when compared with the UCS, SCS, and SHS groups. In the SHS plasma concentration of electrolytes and urinary excretion thereof, fluid excretion, whole blood hemoglobin, hematocrit, plasma osmolality, and plasma protein concentration decreased when compared with the UHS and increased insignificantly when compared with the UCS and SCS groups. It was concluded that FSS may be used to prevent or minimize electrolyte deficiency in endurance-trained volunteers during prolonged restriction of muscular activity.     

The effect of restriction of physical activity on adaptation to prolonged exercise in dogs.

Eight-week restriction of physical activity markedly reduced the capacity for prolonged running. The rate of exercise-induced Tre increases was also significantly higher in comparison with control experiments. At the point of exhaustion blood glucose concentration and muscle glycogen content were similar in the control and cage-confined animals, however the rate of decrease in blood glucose level and muscle glycogen depletion during exercise were higher in the cage-confined dogs than in the controls.     

Rat liver glycogen metabolism in the perinatal period

The correlation between blood glucose levels, the concentration of glycogen, the activities of glycogen sythase and phosphorylase and their respective kinases and phosphatases was examined in liver of rat fetuses between day 18 of gestation and one day after birth. Between day 18 and 21 there is a rapid increase in the concentration of glycogen and in the activity of synthase a and a much slower increase in the activity of phosphorylase a. The activity of the respective kinases increased rapidly during this period and reached maximun on day 21. The activity of synthase phosphatase and phosphorylase phosphatase increased after day 18, to reach a maximum on day 19 and 20, respectively, but decreased again towards day 21. The possibility that the changes in glycogen concentration and enzyme activities were related to an effect of glucose of AMP on the respective phosphatases was considered. It was found that the Km of phosphatase for glucose in the prenatal period was 5–7 mM, as in the adult. Since the level of blood glucose during this period was constant (2.8 mM), an effect of glucose on phosphatase activity seems unlikely. AMP concentration increased between day 18 and 21 from 6–15 nmol/g. In view of the low level of phosphorylase a activity during this period, the increase in AMP concentration is not considered to be important in the regulation of glycogen breakdown at this time.Immediately after birth blood glucose levels dropped to 5 mg/dl. This was accompanied by a rapid decrease in glycogen concentration and in the activity of glycogen synthase and a rise in phosphorylase activity. Blood glucose levels returned to the initial level within 1 h after birth, whereas the changes in glycogen concentration and enzyme activities continued for at least 3 h after birth. On day 22 all parameters examined had reached the level found in adult rat liver.It is suggested that the rapid changes observed immediately after birth are due to an effect of hypoglycemia mediated by hormones and cannot be ascribed to direct effects of metabolites on the enzyme systems involved.     

Renal haemodynamics and the effect of alpha-adrenergic blockade in running and swimming splenectomized dogs

In splenectomized dogs swimming causes a stronger vasoconstriction in the kidney than treadmill running. Renal blood flow measured by electromagnetic flow probes decreased by 10% during treadmill running and by 37% during swimming. The renal perfusion remained low during 30 min after both running and swimming. Arterial pressure increased during running and during swimming. Phenoxybenzamine, an alpha-adrenergic blocking agent, practically abolished the changes in renal perfusion induced by exercise, but not those in arterial pressure. The changes in renal blood flow and arterial pressure were stronger than those found in a previous study in non-splenectomized dogs. We conclude that in splenectomized dogs sympathetic and adrenomedullary response during exercise is increased resulting in a stronger renal vasoconstriction and a more pronounced increase in arterial pressure, than in intact dogs.     

Rat liver glycogen metabolism in the perinatal period.

The correlation between blood glucose levels, the concentration of glycogen, the activities of glycogen synthase and phosphorylase and their respective kinases and phosphatases was examined in liver of rat fetuses between day 18 of gestation and one day after birth. Between day 18 and 21 there is a rapid increase in the concentration of glycogen and in the activity of synthase a and a much slower increase in the activity of phosphorylase a. The activity of the respective kinases increased rapidly during this period and reached maximum on day 21. The activity of synthase phosphatase and phosphorylase phosphatase increased after day 18, to reach a maximum on day 19 and 20, respectively, but decreased again towards day 21. The possibility that the changes in glycogen concentration and enzyme activities were related to an effect of glucose or AMP on the respective phosphatases was considered. It was found that the Km of phosphorylase phosphatase for glucose in the prenatal period was 5--7 mM, as in the adult. Since the level of blood glucose during this period was constant (2.8 mM), an effect of glucose on phosphatase activity seems unlikely. AMP concentration increased between day 18 and 21 from 6--15 nmol/g. In view of the low level of phosphorylase a activity during this period, the increase in AMP concentration is not considered to be important in the regulation of glycogen breakdown at this time. Immediately after birth blood glucose levels dropped to 5 mg/dl. This was accompanied by a rapid decrease in glycogen concentration and in the activity of glycogen synthase and a rise in phosphorylase activity. Blood glucose levels returned to the initial level within 1 h after birth, whereas the changes in glycogen concentration and enzyme activities continued for at least 3 h after birth. On day 22 all parameters examined had reached the level found in adult rat liver. It is suggested that the rapid changes observed immediately after birth are due to an effect of gypoglycemia mediated by hormones and cannot be ascribed to direct effects of metabolites on the enzyme systems involved.     

Oxytocin levels in the posterior pituitary and in the heart are modified by voluntary wheel running

We hypothesized that voluntary wheel running results in increased secretion of oxytocin, a peptide involved in the stress response. An additional hypothesis was that prolonged exercise affects oxytocin levels in the heart, which is in line with the potential role of oxytocin in cardiovascular functions. Voluntary wheel running lasted 3 weeks and daily running distances increased progressively reaching maximum levels about 8 km (Sprague-Dawley rats) and 4 km (Lewis strain). The exercise resulted in significant reduction of epididymal fat, slight increase in glucose transporter GLUT4 mRNA levels and significant enhancement of plasma density. Voluntary exercise failed to influence plasma oxytocin levels either in Lewis or Sprague-Dawley rats, but it resulted in a significant decrease of oxytocin concentrations in the posterior pituitary. Plasma oxytocin concentrations were not modified even if the measurements were made in the dark phase of the day. In voluntary wheel running Sprague-Dawley rats, the content of oxytocin in the right heart atrium was lower than in controls. Thus, the present findings demonstrate that prolonged voluntary wheel running results in a decrease in pituitary oxytocin content without evident changes in hormone concentrations in peripheral blood. However, prolonged exercise used has a significant impact on oxytocin levels in the heart.     

The response of runners to arduous triathlon competition

As very few of the competitors in a triathlon are truly specialist in more than one of the three disciplines, high levels of physical (and mental) stress may result during the course of the event. We investigated some of the physiological responses occurring in runners participating in an "Iron Man" triathlon consisting of canoeing (20 km), cycling (90 km) and running (42 km), in that sequence. Twenty-one male entrants volunteered as subjects for the study. Prior to the competition, maximal oxygen consumption (VO2max) was determined. Basal venous blood samples were collected on the day prior to the competition and post-exercise venous blood samples were collected within 5 minutes of completion of the race. Serum iron was significantly reduced from a mean basal value of 20.6 mumol X l-1 to a mean value of 8.4 mumol X l-1 after the race. Cortisol levels showed a 3 fold increase after the race. Gross VO2max (l X min-1) and mass standardised VO2max (ml X min-1 X kg-1) were both negatively correlated to cortisol levels after the race (p less than 0.05). Total performance time was not related to gross VO2max (l X min-1) but was well correlated to mass corrected VO2max (ml X min-1 X kg-1). The marked fall in serum iron may have been related to heavy sweating or prelatent iron deficiency. Chronic iron deficiency (without frank anaemia) can impair physical performance, although we were unable to show any significant correlation between serum iron level after the race and time taken to complete the event.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of different warm-up procedures on subsequent swim and overall sprint distance triathlon performance

This study investigated the effect of 3 warm-up procedures on subsequent swimming and overall triathlon performance. Seven moderately trained, amateur triathletes completed 4 separate testing sessions comprising 1 swimming time trial (STT) and 3 sprint distance triathlons (SDT). Before each SDT, the athletes completed 1 of three 10-minute warm-up protocols including (a) a swim-only warm-up (SWU), (b) a run-swim warm-up (RSWU), and (c) a control trial of no warm-up (NWU). Each subsequent SDT included a 750-m swim, a 500-kJ (～20 km) ergometer cycle and a 5-km treadmill run, which the athletes performed at their perceived race intensity. Blood lactate, ratings of perceived exertion, core temperature, and heart rate were recorded over the course of each SDT, along with the measurement of swim speed, swim stroke rate, and swim stroke length. There were no significant differences in individual discipline split times or overall triathlon times between the NWU, SWU, and RSWU trials (p > 0.05). Furthermore, no difference existed between trials for any of the swimming variables measured (p > 0.05) nor did they significantly differ from the preliminary STT (p > 0.05). The findings of this study suggest that warming up before an SDT provides no additional benefit to subsequent swimming or overall triathlon performance.     

The effect of long-distance running on plasma immunoreactive glucagon levels

Twelve highly conditioned long-distance runners were studied to determine the effects of marathon (42 km) and 10,000 m running on plasma immunoreactive glucagon (IRG), serum immunoreactive insulin (IRI), and serum glucose (G) levels. Blood samples were drawn just prior to and immediately upon completion of the run. Marathon running resulted in no significant change in G, IRI, or IRG levels. After running 10,000 m, plasma IRG levels did not change significantly, while IRI and G increased significantly. In evaluating the pooled data from both runs, a significant inverse correlation was observed between delta G and delta IRG. This relationship between delta G and delta IRG suggests that glucagon plays a role in maintaining normal blood glucose levels during strenuous exercise.     

Origin of individuality of two daughter cells during the division process examined by the simultaneous measurement of growth and swimming property using an on-chip single-cell cultivation system

We examined the origin of individuality of two daughter cells born from an isolated single Escherichia coli mother cell during its cell division process by monitoring the change in its swimming behavior and tumbling frequency using an on-chip single-cell cultivation system. By keeping the isolated condition of an observed single cell, we compared its growth and swimming property within a generation and over up to seven generations. It revealed that running speed decreased as cell length smoothly increased within each generation, whereas tumbling frequency fluctuated among generations. Also found was an extraordinary tumbling mode characterized by the prolonged duration of pausing in predivisional cells after cell constriction. The observed prolonged pausing may imply the coexistence of two distinct control systems in a predivisional cell, indicating that individuality of daughter cells emerges after a mother cell initiates constriction and before it gets physically separated into two new cell bodies.     

Air pollution and individual productivity: Evidence from the Ironman Triathlon results

The study considers how air quality affects the productivity of physically intensive labor. Namely, we analyze the athletes of the Ironman Triathlon, one of the toughest long-distance triathlon races in the world. Moreover, in this competition, both men and women, professional and amateur athletes, can participate. We consider the results of Ironman Triathlon from 2005 to 2019. Using athlete's finishing time as a dependent variable, we estimate the impact of concentrations of two main air pollutants, O3 and PM2.5. We found triathletes performance decrements in swimming due to high ozone concentration and in bicycle riding and running due to high level of PM2.5. We have also found that professional athletes are less sensitive to air pollution, whereas there is almost no gender difference in the impact of air pollution on athletes’ productivity.     

Thermoregulatory responses to low-intensity prolonged swimming in water at various temperatures and treadmill walking on land

The purpose of the present study was to examine the effect of water temperature on the human body during low-intensity prolonged swimming. Six male college swimmers participated in this study. The experiments consisted of breast stroke swimming for 120 minutes in 23 degrees C, 28 degrees C and 33 degrees C water at a constant speed of 0.4 m.sec-1 in a swimming flume. The same subjects walked on a treadmill at a rate of approximately 50% of maximal oxygen uptake (VO2max) at the same relative intensity as the three swimming trials. Rectal temperature (Tre) in 33 degrees C water was unchanged during swimming for 120 minutes. Tre during treadmill walking increased significantly compared to the three different swimming trials. Tre, mean skin temperature (Tsk) and mean body temperature (Tb) in 23 degrees C and 28 degrees C water decreased significantly more than in both the 33 degrees C water and walking on land. VO2 during swimming in 23 degrees C water increased more than during swimming in the 28 degrees C and 33 degrees C trials; however, there were no significant differences in VO2 between the 23 degrees C swimming trial and treadmill walking. Heart rate (HR) during treadmill walking on land increased significantly compared with HR during the three swimming trials. Plasma adrenaline concentration at the end of the treadmill walking was higher than that at the end of each of the three swimming trials. Noradrenaline concentrations at the end of swimming in the 23 degrees C water and treadmill walking were higher than those during the other two swimming trials. Blood lactate concentration during swimming in 23 degrees C water was higher than that during the other two swimming trials and walking on land. These results suggest that the balance of heat loss and heat production is maintained in the warm water temperature. Therefore, a relatively warm water temperature may be desirable when prolonged swimming or other water exercise is performed at low intensity.     

Spontaneous All-or-Nothing Action Potentials in the Ciliate Bursaridium difficile

The electrical membrane properties and the swimming behaviour of the freshwater ciliate Bursaridium difficile were studied by current clamp recordings and video analysis. The resting membrane potential was –45 ± 6 mV (mean ± SD, n = 80), and the input resistance and membrane capacitance were 109 ± 42 megaohms (MΩ) (n = 63) and 457 ± 150 picofarads (pF) (n = 42), respectively. Based on an estimated surface area of 6.8 × 10^-4 cm², the corresponding specific membrane resistance and capacitance are 7.4 × 10⁴Ω× cm² and 0.7 μF/cm². Bursaridium difficile generates spontaneous, all-or-nothing action potentials with a well-defined threshold in normal medium. The spontaneous firing frequency was 0.22 ± 0.06 Hz (n = 80). The maximum rate of rise of the action potentials was less than 1 V/s, and they displayed a prolonged plateau phase (0.5–1 s). The action potentials were abolished in nominal Ca²⁺-free solution and are thus Ca²⁺-spikes. The swimming pattern of Bursaridium in homogeneous surroundings is composed of forward swimming periods interrupted by regular, short periods of backward swimming followed by a change in the forward swimming direction. The turning frequency corresponded to the spontaneous firing frequency, and only forward swimming was observed in nominal Ca²⁺-free solution. The periods of backward swimming activity are thus linked to the spontaneous action potentials.