A three-week traditional altitude training increases hemoglobin mass and red cell volume in elite biathlon athletes

It is well known that altitude training stimulates erythropoiesis, but only few data are available concerning the direct altitude effect on red blood cell volume (RCV) in world class endurance athletes during exposure to continued hypoxia. The purpose of this study was to evaluate the impact of three weeks of traditional altitude training at 2050 m on total hemoglobin mass (tHb), RCV and erythropoietic activity in highly-trained endurance athletes. Total hemoglobin mass, RCV, plasma volume (PV), and blood volume (BV) from 6 males and 4 females, all members of a world class biathlon team, were determined on days 1 and 20 during their stay at altitude as well as 16 days after returning to sea-level conditions (800 m, only males) by using the CO-rebreathing method. In males tHb (14.0 +/- 0.2 to 15.3 +/- 1.0 g/kg, p < 0.05) and RCV (38.9 +/- 1.5 to 43.5 +/- 3.9 ml/kg, p < 0.05) increased at altitude and returned to near sea-level values 16 days after descent. Similarly in females, tHb (13.0 +/- 1.0 to 14.2 +/- 1.3 g/kg, p < 0.05) and RCV (37.3 +/- 3.3 to 42.2 +/- 4.1 ml/kg, p < 0.05) increased. Compared to their sea-level values, the BV of male and female athletes showed a tendency to increase at the end of the altitude training period, whereas PV was not altered. In male athletes, plasma erythropoietin concentration increased up to day 4 at altitude (11.8 +/- 5.0 to 20.8 +/- 6.0 mU/ml, p < 0.05) and the plasma concentration of the soluble transferrin receptor was elevated by about 11 % during the second part of the altitude training period, both parameters indicating enhanced erythropoietic activity. In conclusion, we show for the first time that a three-week traditional altitude training increases erythropoietic activity even in world class endurance athletes leading to elevated tHb and RCV. Considering the relatively fast return of tHb and RCV to sea-level values after hypoxic exposure, our data suggest to precisely schedule training at altitude and competition at sea level.     

Blood volume and hemoglobin mass in endurance athletes from moderate altitude

PURPOSE: To determine whether total hemoglobin (tHb) mass and total blood volume (BV) are influenced by training, by chronic altitude exposure, and possibly by the combination of both conditions. METHODS: Four groups (N = 12, each) either from locations at sea level or at moderate altitude (2600 m) were investigated: 1) sea-level control group (UT-0 m), 2) altitude control group (UT-2600 m), 3) professional cyclists from sea level (C-0 m), and 4) professional cyclists from altitude (C-2600 m). All subjects from altitude were born at about 2600 m and lived all their lives (except during competitions at lower levels) at this altitude. tHb and BV were determined by the CO-rebreathing method. RESULTS: VO2max (mL x kg(-1) x min(-1)) was significantly higher in UT-0 m (45.3 +/- 3.2) than in UT-2600 m (39.6 +/- 4.0) but did not differ between C-0 m (68.2 +/- 2.7) and C-2600 m (69.9 +/- 4.4). tHb (g x kg(-1)) was affected by training (UT-0 m: 11.0 +/- 1.1, C-0 m: 15.4 +/- 1.3) and by altitude (UT-2600 m: 13.4 +/- 0.9) and showed both effects in C-2600 m (17.1 +/- 1.4). Because red cell volume showed a behavior similar to tHb and because plasma volume was not affected by altitude but by training, BV (mL x kg(-1)) was increased in C-0 m (UT-0 m: 78.3 +/- 7.9; C-0 m: 107.0 +/- 6.2) and in UT-2600 m (88.2 +/- 4.8), showing highest values in the C-2600 m group (116.5 +/- 11.4).CONCLUSION: In endurance athletes who are native to moderate altitude, tHb and BV were synergistically influenced by training and by altitude exposure, which is probably one important reason for their high performance.     

Attenuated ANF response to exercise in athletes with exercise-induced hypoxemia

Some highly trained endurance athletes develop an exercise-induced hypoxemia (EIH) at least partially due to a hemodynamic factor with a potential stress failure on pulmonary capillaries. Atrial natriuretic factor (ANF) is a pulmonary vasodilatator and its release during exercise could be reduced with endurance training. We hypothesized that athletes exhibiting EIH, who have a greater training volume than non-EIH athletes, have a reduced ANF release during exercise explaining the pathophysiology of EIH. Ten highly trained EIH-athletes (HT-EIH), ten without EIH (HT-nEIH), and nine untrained (UT) males performed incremental exercise to exhaustion. No between group differences occurred in resting ANF plasma levels. In contrast to HT-nEIH and UT (p < 0.05), HT-EIH showed a smaller increase in ANF concentration between rest and maximal exercise (HT-EIH: 8.12 +/- 0.69 vs. 14.1 +/- 1.86 pmol x l (-1); HT-nEIH: 10.46 +/- 1 vs. 18.7 +/- 1.8 pmol x l (-1); UT: 6.23 +/- 0.95 vs. 20.38 +/- 2.79 pmol x l (-1)). During the recovery, ANF levels decreased significantly in HT-nEIH and UT groups (p < 0.05). Electrolyte values increased in all groups during exercise but were higher in both trained groups. In conclusion, this study suggested that ANF response to exercise may be important for exercise-induced hypoxemia.     

Sensitivity of the physiologically hypertrophied heart to isoproterenol

Cardiovascular reactions to isoproterenol stimulation (2 and 4 micrograms/min for 12 min each) were evaluated in seven endurance-trained athletes (marathon runners, VO2 max 66.0 +/- 3.7 ml/kg) and seven untrained subjects (VO2 max 54.4 +/- 3.6 ml/kg). At rest and during stimulation, the heart rate, blood pressure as well as one-dimensional (end-diastolic and end-systolic dimensions, shortening fraction) and two-dimensional (end-diastolic and end-systolic volumes, ejection fraction, stroke volume, cardiac output) echocardiographic parameters were determined. The increase in the heart rate of the endurance-trained athletes (28%; 2 micrograms/min) (58%; 4 micrograms/min) was less than in the untrained controls (34%/76%). The blood pressure behaved similarly in both groups. The stroke volume of the endurance-trained subjects rose during stimulation (14%, 4 micrograms/min); the end-diastolic volume remained nearly constant as the end-systolic emptying increased. The stroke volume of the untrained subjects tended to decrease as the end-diastolic and end-systolic volumes were reduced. In absolute terms, the shortening fraction and ejection fraction were identical. Referring to the heart rate, however, they were elevated in the endurance-trained subjects. Hence, under isoproterenol the rise in heart rate was weaker and the increase in ventricular performance seemed to be stronger in the trained subjects compared to the untrained controls. The causes appear to be different regulative effects of the autonomic nervous system on the sinus node and the ventricular myocardium; intrinsic cardiac mechanisms remain to be discussed.     

Aerobic fitness: II. Orthostasis and VO2peak following head-down tilt.

To determine whether endurance exercise trained (ET) subjects would experience greater reductions in peak oxygen delivery and orthostatic tolerance (OT) than untrained (UT) subjects, both peak oxygen uptake (VO2peak) during upright bicycle ergometry and tolerance time during 70 degrees head-up tilt (HUT) were compared within and between groups before and after 4 h of -6 degrees head-down tilt (HDT). Eight ET subjects with a mean VO2peak of 61.7 +/- 1.6 ml.kg-1.min-1 were matched for age, height, and weight with eight UT subjects (VO2peak = 38.4 +/- 1.7 ml.kg-1.min-1). Following HDT, decreases in plasma volume (PV) were larger for ET subjects (-3.7 +/- 0.5 ml.kg-1) than for UT subjects (-2.3 +/- 0.3 ml.kg-1), P less than 0.03. Reductions in VO2peak for ET subjects (-5.4 +/- 1.1 ml.kg-1.min-1) were also greater than for UT subjects (-2.4 +/- 0.8 ml.kg-1.min-1), P less than 0.05. The ET (N = 6) subjects also had a significant decrease in OT time (-13.0 +/- 4.2 min) during post-HDT HUT, which was not observed for the UT group (N = 6). A significant inverse correlation was found pre-HDT VO2peak and the change in OT time, r = -0.74, P less than 0.01. The decrease in OT was also significantly correlated to the PV decrease, r = 0.59, P less than 0.04. The UT subjects had significantly augmented pressor responses to HUT manifested by the increases in both HR and MAP following HDT.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induced hypervolemia, cardiac function, VO2max, and performance of elite cyclists.

OBJECTIVE: To determine whether plasma volume expansion (PVexp) in elite endurance-trained (ET) cyclists, who already possess both a high blood volume (BV) and a high VO2max, leads to further enhancements in their cardiac function, VO2max, and endurance performance (time to exhaustion at 95% VO2max). METHODS: Nine male ET cyclists (V02max = 68.9 +/- 0.6 (SEM) mL x kg(-1) x min(-1)) were studied employing a double blind, cross-over design; i) before PVexp, ii) after sham PVexp (Sham), iii) after restoration of normocythemia, iv) after PVexp (6% dextran), and v) upon reestablishment of normocythemia. RESULTS: PVexp resulted in a 547 +/- 61 mL increase in BV (P < 0.05). Maximal cardiac output and maximal stroke volume were higher (P < 0.05) after PVexp, but the magnitude of these increases was only sufficient to counter the hemodilution effect (lowered O2 content) of PVexp, such that O2 transport, VO2max, and endurance performance remained unchanged. CONCLUSIONS: Expansion of BV in elite ET cyclists, who already possess a high BV, does not improve their VO2max and endurance performance. Elite ET athletes may already be at an optimal BV, which is at or near the limits of their diastolic reserve capacity.     

Hematological indices and iron status in athletes of various sports and performances

PURPOSE: Alterations of the red blood cell system and iron metabolism can influence physical performance. On the other hand, exercise can influence hematological variables. The purpose of this epidemiological study was to investigate the characteristics of the red blood cell system and the iron metabolism in athletes of different sporting disciplines and at different levels of performance. METHODS: We studied 851 male subjects (747 athletes, 104 untrained controls). Hemoglobin (Hb), hematocrit (Hct), red blood cell count (RBC), iron, transferrin, ferritin (Fer), and haptoglobin were analyzed in standardized blood samples, obtained after 2 d of rest, considering levels of performance (internationally, nationally, locally competitive, and leisure time), distinctive sporting category (endurance- (END), strength- (POW), and mixed-trained (MIX)), and, within endurance athletes, distinctive disciplines (cycling (CYC) and running (RUN)). RESULTS: No difference was found between athletes and controls in Hb and Hct. Reduced Hb, Hct, and RBC levels were observed in END compared with POW and MIX. These findings can mainly be attributed to exercise-induced plasma volume expansion, and only to a lesser degree and in selected athlete populations to hemolysis, as low haptoglobin is only observed in RUN, not in CYC, suggesting that not exercise itself but the "traumatic" movement of running might trigger the destruction of red blood cells. Physical activity of increasing duration and workloads (leisure time compared with competitive athletes) leads to decreased Fer levels in athletes, disregarding their discipline, but more pronounced in RUN. CONCLUSION: Physical training itself has no significant effect on selected hematological variables in athletes compared with untrained controls. The specific type and duration of exercise is of major importance in the adaptations of the blood cell system and the iron metabolism.     

Basophil releasability in young highly trained and older athletes

PURPOSE: Exercise-induced hypoxemia in highly trained athletes is associated with an increase in histamine release during exercise. The cells most implicated in blood histamine release are basophils. The aim of this study was to determine whether high-level endurance training induces modifications in histamine releasability from human basophils. METHODS: Seven young highly trained athletes (YA) [aged 26.1+/-1.3 yr (mean +/- SEM)] and seven master athletes (MA) (64.4+/-4.1 yr), all known to develop exercise-induced hypoxemia, were respectively compared with seven young untrained men (YC) (23.0+/-1.5 yr) and seven older untrained men (OC) (61.6+/-1.3 yr). During an incremental exhaustive exercise, blood samples for measurement of anti-IgE-induced histamine release from leukocytes were drawn at rest, VO2max, and recovery. RESULTS: Basophils from "leukocyte-rich" supernatant in YA and MA showed significantly higher histamine release induced by anti-IgE (1 microg x mL(-1) than, respectively, YC (P<0.01) and OC (P<0.05) at rest, VO2ax (P<0.01), and recovery (P<0.01). Basophils in YA and MA also showed a histamine release induced by anti-IgE that was higher at VO2max than at rest (respectively. P<0.01 and P<0.05), but this change was not found in the control groups. CONCLUSION: In conclusion, the basophils in highly trained endurance athletes, both young and older, showed higher anti-IgE-induced histamine release than those of untrained men. This effect of high-level training seemed to be potentiated by exercise.     

Cardiac responses to progressive upright exercise in adult male cyclists

AIM: Previous investigations have indicated that maximal stroke volume is the primary factor which differentiates physiological aerobic fitness (VO2max) in endurance athletes from nonathletes. Understanding the pattern of stroke volume response to progressive exercise may provide insights into the mechanisms which are responsible for this difference. METHODS: Doppler echocardiography was used to estimate stroke volume changes with maximal upright cycle exercise in 8 highly trained adult cyclists (mean age 30.5+/-1.6 years) and 16 age-matched nontrained males. Ventricular dimensions were measured during exercise using 2-dimensional echocardiography (parastemal long axis view). Findings were compared to a group of untrained adult male subjects. RESULTS: Mean maximal oxygen uptake was 73.7+/-7.0 and 47.4+/-7.5 ml x kg(-1) x min(-1) in the 2 groups, respectively. Stroke volume rose in both the cyclists and nontrained subjects at the onset of exercise but then plateaued without significant change to exhaustion. Values for stroke index were significantly greater at rest and all levels of exercise in the cyclists (maximal 85+/-13 versus 61+/-13 ml x m(-2)). Two dimensional echocardiograms during exercise in the cyclists revealed a small initial rise in left ventricular end-diastolic dimension and then a small decline, while systolic dimension decreased progressively, resulting in a rise in shortening fraction. CONCLUSION: These findings are consistent with the concept that determinants of stroke volume at rest are most influential in defining differences in maximal stroke volume between athletes and nonathletes.     

Physiological profile of handball players

BACKGROUND: The purpose of this study was to determine the physiological profile of handball players compared to sprinters, endurance trained and untrained subjects. METHODS: Forty-six subjects aged between 19 and 28 years took part in this study: 10 were national handball players (NHB); 7 were international handball players (IHB), 11 were sprint trained subjects (ST); 8 were endurance trained subjects (ET); and 10 were untrained subjects (UT). They performed an incremental treadmill test to determine the maximal oxygen uptake (VO2max), and a Wingate anaerobic test (WanT) to determine maximal power (Wmax). Plasma lactate (La) concentration was measured 5 minutes after the end of the Wingate-test. RESULTS: The VO2max of NHB was similar to that of the IHB and ST athletes but higher than that of the untrained and lower than the endurance trained athletes. Values for Wmax were similar in the IHB and NHB groups and very close to the sprinters. When normalized for body mass or to lean body mass, Wmax was greater in handball players when compared to untrained or endurance trained subjects. Lactate values were in the same range in the NHB, IHB and ST groups and were statistically higher in the NHB and IHB groups than in the UT or ET groups. CONCLUSIONS: The results suggest that the anaerobic metabolism seems to be important for the handball players similarly to sprinters. Since handball is known as a sport with typically short exercise periods of high intensity alternating with rests, anaerobic metabolism appears then to be higbly relevant to performance.     

Cardiac response to acute coronary artery occlusion in exercise-trained dogs.

Exercise training is thought to exert a beneficial effect on cardiovascular function, but its effect in the normal heart following acute coronary artery occlusion is still uncertain. Studies were performed in 12 untrained (UT) and 14 endurance-trained (ET) pentobarbital anesthetized dogs. Left ventricular pressure (LVP), heart rate (HR), percent regional myocardial segmental shortening (%SL), and peripheral coronary pressure (PCP) distal to the occlusion were measured during control conditions and during a 2-min circumflex artery occlusion (CAO). During CAO, LVP, dP/dtmax, and %SL in the ischemic region were significantly reduced in both UT and ET dogs. There was no significant difference between the two groups. In addition, PCP decreased to 27 +/- 5 mm Hg and 26 +/- 9 mm Hg in the UT and ET groups, respectively, during CAO indicating no difference in coronary collateral perfusion between the groups. Regional myocardial blood flow was measured using tracer microspheres in eight of the UT and six of the ET dogs, and the decrease in blood flow to the ischemic zone during CAO was similar in both groups. These results indicate that 12-wk of endurance training does not exert a protective effect on myocardial contractile function or on myocardial perfusion in the central ischemic region during CAO in the anesthetized dog.     

Aerobic fitness: I. Response of volume regulating hormones to head-down tilt.

We investigated the relationship of aerobic fitness to the response of volume-regulating hormones to acute simulated microgravity. Six untrained (UT) and six endurance-trained (ET) healthy young males were studied in the head-down tilt (HDT) position of -6 degrees for 4 h. Peak oxygen uptake (VO2peak) and plasma volume (PV) were significantly greater in the ET (VO2peak = 61.7 +/- 1.6 ml.min-1.kg-1 and PV = 53.1 +/- 2.8 ml.kg-1) than in the UT (VO2peak = 38.4 +/- 1.7 ml.min-1.kg-1 and PV = 38.8 +/- 1.0 ml.kg-1). Plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), norepinephrine (NE), renin activity (PRA), and aldosterone (PA) were measured prior to HDT and at minutes 2, 5, 15, 30, 60, 120, 180, and 240 during HDT. PRA and PA significantly decreased during the time of HDT in both groups. The changes in ANP and NE concentrations were not significantly different between the groups nor across time. However, in the ET subjects, the changes in PRA and NE were significantly correlated with the changes in ANP (r = 0.49, P less than 0.01; and r = 0.86, P less than 0.001, respectively); in the UT subjects, the changes in AVP, PRA, and PA were significantly associated with changes in NE (r = 0.34, P less than 0.03; and r = 0.59; and r = 0.53, P less than 0.01, respectively). PV significantly decreased during HDT, and was primarily related to the decrease in PA in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lower thermic effect of a meal post-exercise in aerobically trained and resistance-trained subjects

Despite the abundance of literature concerning the thermic effect of a test meal (TEM) at rest in trained and untrained subjects, there is little information available concerning the TEM post-exercise. Therefore, it was the purpose of this study to examine the metabolic response to a 763-kcal meal prior to 30 min of exercise at 50% VO2max, in aerobically trained (AT, N = 8), resistance-trained (RT, N = 8), and untrained (UT, N = 8) subjects. Mean (+/- SEM) VO2max was 60.7 +/- 2.3 ml.kg-1.min-1, 52.9 +/- 2.2 ml.kg-1.min-1 and 51.1 +/- 2.2 ml.kg-1.min-1, for the AT, RT, and UT groups, respectively. Mean (+/- SEM) percent fat was 13.7 +/- 1.2, 12.7 +/- 1.9, and 16.9 +/- 1.4 for the AT, RT, and UT groups, respectively. Post-exercise VO2 was measured by indirect calorimetry every half hour, on two nonconsecutive days (post-absorptive (PA) post-exercise and post-prandial (PP) post-exercise) for 3 h. The total TEM (post-exercise PP VO2 minus post-exercise PA VO2) was 4.86 +/- 1.62, 5.22 +/- 1.80, and 9.36 +/- 5.08 I for the AT, RT, and UT groups, respectively. The TEM post-exercise was significantly lower (P less than 0.05) for the AT and RT groups compared with the UT group. Respiratory exchange ratio (R) differed significantly only during the PA post-exercise condition, with the AT group exhibiting significantly lower (P less than 0.01) values compared with the RT and UT groups. PA post-exercise R for the RT group was not significantly different (P = 0.09) from the UT group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endurance training enhances critical power.

The present investigation was conducted to determine whether critical power (CP) assesses the ability to perform continuous aerobic exercise and to determine whether training-induced changes in aerobic endurance are reflected by changes in the slope, but not the y-intercept of the CP function. Twelve healthy, active, but untrained male students (mean age +/- SD = 19.1 +/- 0.8 yr) undertook 8 wk of cycle ergometer endurance training (30-40 min a day, three times a week) at an intensity corresponding to their CP. Six control subjects of similar age and initial training status refrained from regular exercise for the same period. Before and immediately following the training period, each of the 18 participants completed three cycle ergometer tests to determine their CP function, an incremental exercise task to establish their maximal oxygen uptake (VO2max), and 40 min of continuous cycle ergometry at or near their calculated CP. CP was significantly correlated with endurance time at 270 W (r = 0.65, P < 0.05) and with the mean power that could be maintained for 40 min (r = 0.87-0.95, P < 0.01), but overestimated the latter by less than 6%. In response to endurance training, CP increased from a mean of 196 +/- 40.9 W to 255 +/- 28.4 W (31%) (ANCOVA, P < 0.01), while the mean power output maintained for 40 min of exercise increased from 190 +/- 34.5 W to 242 +/- 34.9 W (28%). VO2max increased from 49.2 +/- 7.8 ml.kg-1.min-1 to 53.4 +/- 6.4 ml.kg-1.min-1 (8.5%) (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Determining anaerobic capacity using treadmill ergometry

The determination of anaerobic capacity (AC) using treadmill ergometry is problematic from a methodological, as well as a technical standpoint. In this study, a procedure from Monod and Scherrer was modified to examine whether realistic magnitudes of AC could be determined using three subject groups with different levels of anaerobic training. The subject groups consisted of 10 untrained (UT), 10 aerobic-trained runners (AeT), and 10 anaerobic-trained 400-meter sprinters (AnT). In two separate test series, first the VO2max was determined and second the so-called individual anaerobic threshold (IAT) was used to determine the aerobic power for all subjects. Then all subjects completed a series of sprints with increasing speeds above the VO2max, from which the work output from each test was calculated. Through linear regression, the point of intersection of the regression line with the y-axis was defined as global AC. The results show typically higher VO2max and IAT for AeT (62.2 ml x kg(-1) x min(-1), 14.7 km x h(-1)) compared to UT (53.2 ml x kg(-1) x min(-1); 11.2 km x h(-1)) and AnT (56.7 ml x kg(-1) x min(-1); 11.8 km x h(-1)). AC was significantly higher in AnT (4.1 +/- 0.58 kJ) compared to AeT (1.8 +/- 0.65 kJ) and UT (3.2 +/- 0.68 kJ). The determined absolute values of AC are considerably lower than of comparable examinations using bicycle ergometry. One reason for such an underestimation of AC could be that the horizontal work done during exercise on a treadmill was not taken into enough consideration. Another explanation is that the magnitude of the calculated AC values shows a dependency on the duration of each sprint test. In addition, the critical velocity for all subjects was found to be higher than for IAT, which consequently leads to an underestimation of AC. Moreover, the absolute level of the AC values appears to depend on the endurance of the comparison groups. It can then be concluded that the applied procedure allows for a differentiation amongst a variously trained collective, but does not allow a correct absolute determination of the AC.     

Cardiac responses to exercise in competitive child cyclists

PURPOSE: Cardiovascular responses to exercise in highly trained child endurance athletes have not been well-defined. This study compared hemodynamic responses with progressive cycle exercise in seven competitive child cyclists (mean age 11.9 yr) compared with 39 age-matched untrained boys. METHODS: Doppler echocardiography and gas exchange variables were utilized to assess cardiovascular changes during submaximal and maximal exercise. RESULTS: Mean VO2max was 60.0 (+/-6.0) and 47.0 (+/-5.8) mL x kg(-1) x min(-1) in the cyclists and nonathletes, respectively. At rest and maximal exercise, the cyclists demonstrated greater stroke index than the untrained subjects (resting mean 59 (+/-6) vs 44 (+/-9) mL x m(-2); maximal mean 76 (+/-6) vs 60 (+/-11) mL x m(-2)), but the ratio of maximal:rest stroke index was similar in both groups (1.31 for cyclists, 1.41 for nonathletes). Both groups showed a plateau in stroke volume beyond low-intensity work levels. No significant difference was observed in maximal arteriovenous oxygen difference. CONCLUSIONS: These findings indicate that 1) maximal stroke volume is the critical determinant of the high VO2max in child cyclists and 2) factors that influence resting stroke volume are important in defining VO2max differences between child endurance athletes and untrained boys.     

Muscle oxygenation and fascicle length during passive muscle stretching in ballet-trained subjects

Muscle stretching transiently decreases muscle-blood flow corresponding to a muscle extension. It may disturb a balance between muscular oxygen demand and oxygen supply to muscles and reduce muscle oxygenation. However, muscle-stretching training may improve blood circulatory condition, resulting in the maintained muscle oxygenation during muscle stretching. The aim of this study was to investigate changes in muscle-blood volume (tHb) and tissue oxygenation index (TOI) during muscle stretching determined by using near-infrared spectroscopy (NIRS) in ballet-trained (BT) and untrained (C) subjects. 11 BT women who regularly perform muscle stretching and 11 C women participated in this study. Fascicle lengths, tHb and TOI in the tibialis anterior muscle were measured during passive plantar flexion from ankle joint angles of 120° (baseline) to 140°, 160°, the maximal comfortable position without pain (CP), and the maximal position (MP). At 160°, the % fascicle-length change from baseline was significantly lower in the BT than the C group, however, for the changes in tHb and TOI the significant interaction effect between the 2 groups was not detected. On the other hand, although the increases in the fascicle length from baseline to CP and MP were greater in BT than C, the tHb and TOI reductions were comparable between groups. We concluded that it appears that BT can extend their muscles without excessive reduction in muscle-blood volume and muscle oxygenation at relatively same but absolutely greater muscle-stretching levels than C. The attenuation in these indices during high-level muscle stretching may be associated with the repetitive muscle stretching of long-term ballet training.     

Heart rate and blood pressure variability during heavy training and overtraining in the female athlete

We investigated heavy training- and overtraining-induced changes in heart rate and blood pressure variability during supine rest and in response to head-up tilt in female endurance athletes. Nine young female experimental athletes (ETG) increased their training volume at the intensity of 70-90% of maximal oxygen uptake (VO2max) by 125% and training volume at the intensity of < 70% of VO2max by 100% during 6-9 weeks. The corresponding increases in 6 female control athletes were 5% and 10%. The VO2max of the ETG and the control athletes did not change, but it decreased from 53.0 +/- 2.2 ml x kg(-1) x min(-1) to 50.2 +/- 2.3 ml x kg(-1) x min(-1) (mean+/-SEM, p < 0.01) in five overtrained experimental athletes. In the ETG, low-frequency power of R-R interval (RRI) variability during supine rest increased from 6 +/- 1 ms2 x 10(2) to 9 +/- 2 ms2 x 10(2) (p < 0.05). The 30/15 index (= RRI(max 30)/RRI(min 15), where RRI(max 30) denotes the longest RRI close to the 30th RRI and RRI(min 15) denotes the shortest RRI close to the 15th RRI after assuming upright position in the head-up tilt test), decreased as a result of training (analysis of variance, p = 0.05). In the ETG, changes in VO2max were related to the changes in total power of RRI variability during standing (r = 0.74, p < 0.05). Heart rate response to prolonged standing after head-up tilt was either accentuated or attenuated in the overtrained athletes as compared to the normal training state. We conclude that heavy training could increase cardiac sympathetic modulation during supine rest and attenuated biphasic baroreflex-mediated response appearing just after shifting to an upright position. Heavy-training-/overtraining-induced decrease in maximal aerobic power was related to decreased heart rate variability during standing. Physiological responses to overtraining were individual.     

31P-MRS characterization of sprint and endurance trained athletes

Muscle metabolism and force production were studied in sprint trained runners, endurance trained runners and in untrained subjects, using 31P-MRS. 31P-spectra were obtained at a time resolution of 5 s during four maximal isometric contractions of 30-sec duration, interspersed by 60-sec recovery intervals. Resting CrP/ATP ratio averaged 3.3 +/- 0.3, with no difference among the three groups. The sprint trained subjects showed about 20 % larger contraction forces in contraction bouts 1 and 2 (p < 0.05). The groups differed with respect to CrP breakdown (p < 0.05), with sprinters demonstrating about 75 % breakdown in each contraction compared to about 60 % and 40 % for untrained and endurance trained subjects, respectively (p < 0.05). The endurance trained runners showed almost twice as fast CrP recovery (t 1/2 = 12.5 +/- 1.5) compared to sprint trained (t 1/2 = 22.5 +/- 2.53) and untrained subjects (t 1/2 = 26.4 +/- 2.8). From the initial rate of CrP resynthesis the rate of maximal aerobic ATP synthesis was estimated to 0.74 +/- 0.07, 0.73 +/- 0.10 and 0.33 +/- 0.07 mmol ATP x kg -1 wet muscle x sec -1 for sprint trained, endurance trained and untrained subjects, respectively. Only the sprint trained and the untrained subjects displayed a significant drop in pH and only during the first of the four contractions, about 0.2 and 0.1 pH units, respectively, indicating that only under those contractions was the glycolytic proton production larger than the proton consumption by the CK reaction. Also, in the first contraction the energy cost of contraction was higher for the sprinters compared to the two other groups. The simple 31P-MRS protocol used in the present study demonstrates marked differences in force production, aerobic as well as anaerobic muscle metabolism, clearly allowing differentiation between endurance trained, sprint trained and untrained subjects.     

Training status (endurance or sprint) and catecholamine response to the Wingate-test in women

The aim of this study was to verify if, as for men, training status induces different catecholamine responses to exercise. To do this, we investigated the effect of training status (sprint or endurance) on plasma catecholamine response to a supramaximal exercise in women. Nineteen subjects took part in our study: six untrained subjects (UT), seven endurance trained subjects (ET) and six sprint trained ones (ST). The trained subjects (ET and ST) were all competing at a high national level. The maximal power (W max ) and the mean power (W) were determined from the Wingate-test. Blood lactate, adrenaline (A) and noradrenaline (NA) were analysed at rest (La 0, A 0 and NA 0 ), immediately at the end of the exercise (A max and NA max ) and after 5 min recovery (La max [3 min in arterialized blood], A 5 and NA 5 ). The disappearance of A and NA was judged by the ratio (A max -A 5 )/A max and (NA max -NA 5 )/NA 5. The ratio A max /NA max was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. As expected, during the Wingate-test ST exhibited significantly higher performances compared to UT and ET. But in contrast to the men's data no difference was observed between the three groups both for La max (13.1 +/- 0.8 mmol x L (-1); 14.8 +/- 1.0 mmol x L (-1) and 11.2 +/- 0.5 mmol x L (-1) respectively for ET, ST and UT), NA max (22.1 +/- 1.2 nmol x L (-1); 13.1 +/- 2.4 nmol x L (-1) and 20.2 +/- 7 nmol x L (-1)respectively for ET, ST and UT) and A max (4.1 +/- 0.8 nmol x L (-1); 2.6 +/- 0.6 nmol x L (-1); 13.1 +/- 0.6 nmol x L (-1) respectively for ET, ST and UT). Consequently the ratio A max /NA max was similar in UT, ET and ST (respectively 0.2 +/- 0.03; 0.2 +/- 0.04; 0.17 +/- 0.04), These results indicated, in contrast to the men's data, that the catecholamine response to the Wingate-test did not differ between female subjects of different status of training. In conclusion this study did not find any significant effect of training status on the catecholamine response to supramaximal exercise and so argues in favour of sex differences in response to training.