Physiological characteristics of elite sport-dancers.

AIM: Dancesport is increasing its popularity and it becomes to be considered as a real sport. Few studies are available about the physiological strain of dancesport competitions: moreover, recent changes in the official rules make it mandatory to revise our knowledge about the specific physiologic demands during competition. The aim of our study was to evaluate physiological parameters in top-level dancers. METHODS: Twelve competitive dancesport couples (12 Latin-American and 12 Standard dancers) composed the study population. The first testing session was aimed at determining physical and physiological characteristics of athletes in laboratory; the second, at establishing physiological responses during simulated competition on field, involving the measurement of O(2) uptake (VO(2)), heart rate and blood lactate (BL). RESULTS: Male dancers showed a peak-VO(2) of 60.9±6.0 and 59.2±7.0 mL/kg/min for Standard and Latin-American dancers, respectively. For females, peak-VO(2) was 53.7±5.0 mL/kg/min in Standard and 52.3±5.0 mL/kg/min in Latin-American dancers. During simulated competition, male dancers reached the 75.7±10.6 and 84.2±11.2% of peak-VO(2) (P<0.05) for Standard and Latin-American sequence, respectively. For females, no difference was observed (70.8±13.8% in Latin-American and 72.5±12.8% in Standard). Peak-BL during simulated Standard competition was 6.50±2.1 and 6.91±2.6 mM in males and females, respectively, and, for Latin-American sequence, 7.95±2.1 mM in males and 6.04±2.5 mM in females. CONCLUSION: Dancesport can be defined as a sport discipline with an alternate physical activity with medium lasting and high energy-demanding (both aerobic and anaerobic) consecutive phases, separated by short recovery periods. These data must be kept into account while planning specific training programs in sportdancers.

Baseline simple and complex reaction times in female compared to male boxers.

AIM: The aim of the study was to compare baseline cognitive performance of female in respect to male amateur boxers. METHODS: Study population included 28 female amateur boxers. Fifty-six male boxers, matched for age, employment and competitive level to female athletes, formed the control group. All boxers had no history of head concussions (except boxing). Each boxer was requested to: 1) fulfill a questionnaire collecting demographic data, level of education, occupational status, boxing record and number of head concussions during boxing; 2) undergo a baseline computerized neuropsychological (NP) test (CogSport) measuring simple and complex reaction times (RT). RESULTS: Female were lighter than male boxers (56±7 vs. 73.1±9.8 kg, P<0.0001). No significant differences at CogSport scores were observed between groups. Male boxers showed a longer simple-RT at the end of the NP battery than at the beginning (0.247±0.007 vs. 0.243±0.007 s, P=0.02), however, with a significant lower rate of mistakes (0.7±1.6 vs. 2.0±3.1%, P=0.005), observed also in the female group (0.5±1.1 vs. 2.2±3.0%, P=0.005). No boxing activity parameter (record, number of knock-outs, etc.) correlated with NP scores. CONCLUSION: Female and male Olympic-style boxers have no (or minimal) differences in baseline cognitive performance. Further research with larger series of female boxers is required to confirm these findings.

Auxiliary muscles and slow component during rowing.

The aim of this study was to investigate the contribution of the auxiliary muscles, utilized to sustain the subject's position on the ergometer, to the oxygen uptake slow component phenomenon. Three tests were performed at the same severe relative intensity on a rowing ergometer: a standard rowing exercise test, a rowing exercise performed with the arms and one performed with the legs only. During the three exercise modalities, oxygen uptake, local oxyhemoglobin saturation and surface electromyography signals of the trapezius and vastus lateralis muscles were measured. The slow component amplitude, in absolute values, resulted statistically lower for rowing (343.9 ml . min (-1)) than for arms (795.6 ml . min (-1)) and legs (695.8 ml . min (-1)) exercise modes. The same result was found when the slow component amplitude was calculated as percentage of V O (2peak) (7.1 % for rowing; 17.2 % for arms; 17.3 % for legs). The lower slow component amplitude measured for the rowing exercise mode with respect to both arms and legs modes, demonstrates that the auxiliary muscles involved in the exercise contribute to the increasing energetic cost due to the slow component.

Energy cost of swimming of elite long-distance swimmers.

The aim of this study was: (1) to assess the energy cost of swimming (C(s), kJ km(-1)) in a group of male (n = 5) and female (n = 5) elite swimmers specialised in long-distance competitions; (2) to evaluate the possible effect of a 2-km trial on the absolute value of C(s). C(s) was assessed during three consecutive 400-m trials covered in a 50-m pool at increasing speeds (v1, v2, v3). After these experiments the subjects swam a 2-km trial at the 10-km race speed (v2km) after which the three 400-m trials were repeated at the same speed as before (v5 = v1, v6 = v2, v7 = v3). C(s) was calculated by dividing the net oxygen uptake at steady state VO2ss by the corresponding average speed (v, m s(-1)). VO2ss was estimated by using back extrapolation technique from breath-to-breath VO2 recorded during the first 30 s of recovery after each test. C(s) increased (from 0.69 kJ m(-1) to 1.27 kJ m(-1)) as a function of v (from 1.29 m s(-1) to 1.50 m s(-1)), its values being comparable to those measured in elite short distance swimmers at similar speeds. In both groups of subjects the speed maintained during the 2-km trial (v2km) was on the average only 1.2% faster than of v2 and v6 (P>0.05), whereas C(s) assessed at the end of the 2-km trial (v2km) turned out to be 21 +/- 26% larger than that assessed at v2 and v6 (P<0.05); the average stroke frequency (SF, cycles min(-1)) during the 2-km trial turned to be about 6% (P<0.05) faster than that assessed at v2 and v6. At v5, C(s) turned out to be 19 +/- 9% (P<0.05) and 22 +/- 27% (0.1 < P = 0.05) larger than at v1 in male and female subjects (respectively). SF was significantly faster (P<0.05, in male subjects) and the distance per stroke (Ds = v/SF) significantly shorter (P<0.05) in female subjects at v5 and v6 than at v1 and v2. These data suggest that the increase of C(s) found after the 2-km trial was likely related to a decrease in propelling efficiency, since the latter is related to the distance per stroke.

Familial hypercholesterolemia in St-Petersburg: the known and novel mutations found in the low density lipoprotein receptor gene in Russia.

BACKGROUND: Familial hypercholesterolemia is a human monogenic disease caused by population-specific mutations in the low density lipoprotein (LDL) receptor gene. Despite thirteen different mutations of the LDL receptor gene were reported from Russia prior to 2003, the whole spectrum of disease-causing gene alterations in this country is poorly known and requires further investigation provided by the current study. METHODS: Forty-five patients with clinical diagnosis of FH were tested for the apolipoprotein B (apoB) mutation R3500Q by restriction fragment length analysis. After exclusion of R3500Q mutation high-sensitive fluorescent single-strand conformation polymorphism (SSCP) analysis and automatic DNA sequencing were used to search for mutations in the LDL receptor gene. RESULTS: We found twenty one rare sequence variations of the LDL receptor gene. Nineteen were probably pathogenic mutations, and two (P518P, T705I) were considered as neutral ones. Among the mutations likely to be pathogenic, eight were novel (c.670-671insG, C249X, c.936-940del5, c.1291-1331del41, W422X, c.1855-1856insA, D601N, C646S), and eleven (Q12X, IVS3+1G>A, c.651-653del3, E207X, c.925-931del7, C308Y, L380H, c.1302delG, IVS9+1G>A, V776M, V806I) have already been described in other populations. None of the patients had the R3500Q mutation in the apoB gene. CONCLUSIONS: Nineteen pathogenic mutations in the LDL receptor gene in 23 probands were identified. Two mutations c.925-931del7 and L380H are shared by St.-Petersburg population with neighbouring Finland and several other mutations with Norway, Sweden or Denmark, i.e. countries from the Baltic Sea region. Only four mutations (c.313+1G>A, c.651-653del3, C308Y and W422X) were recurrent as all those were found in two unrelated families. By this study the number of known mutations in the LDL receptor gene in St.-Petersburg area was increased nearly threefold. Analysis of all 34 low density lipoprotein receptor gene mutations found in St.-Petersburg argues against strong founder effect in Russian familial hypercholesterolemia.

VO2 slow component correlates with vastus lateralis de-oxygenation and blood lactate accumulation during running.

BACKGROUND: In the present study, vastus lateralis de-oxygenation was monitored contemporarily with VO2 changes along a severe constant intensity running exercise, after the 3rd min up to volitional exhaustion. Blood lactate accumulation was also measured before, during and after running. METHODS: Eleven male amateur soccer players volunteered for the study. Subjects mean age, height, and body weight were 22.9+/-2 yrs, 177.5+/-6.2 cm, 71.7+/-4 kg, respectively. Measurements were carried out during running on a treadmill. Ventilatory and gas exchange parameters were measured at the mouth on a breath-by-breath basis. For blood lactate concentration accumulation measurement, capillary blood samples were taken from the fingertip. The oxygenation of the vastus lateralis muscle were measured by a continuous wave NIRS portable instrument. By means of two pretests the onset of [La]b accumulation and its associated velocity (vOBLA), and the peak of oxygen uptake and its associated velocity (vVO2,peak) were assessed. The test consisted of running on the treadmill up to volitional exhaustion at a constant velocity corresponding to vOBLA plus 50% of the difference between vVO2,peak and vOBLA (v50%Delta). RESULTS: The principal finding of this study was that vastus lateralis de-oxygenation changes measured during running correlate with a) oxygen uptake changes between the 3rd min of exercise and the time corresponding to the subject's volitional exhaustion; b) blood lactate concentration increments measured at the 3rd and the 6th min of exercise and at the time corresponding to the subject's volitional exhaustion. CONCLUSIONS: In conclusion, the results of the present study support our hypothesis that the vastus lateralis de-oxygenation contributes consistently to the VO2 slow component development in running.

The VO2 slow component in swimming.

All studies on the oxygen uptake (VO2) slow component have been carried out for the sporting disciplines of cycling or running, but never for swimming. Considering that front crawl swimming is a sport discipline that is fundamentally different from both running and cycling, the aim of this study was to verify whether this slow component also appears in swimming. Six elite pentathletes were tested in a swimming flume while front crawl swimming to exhaustion. Swimming velocity for the slow component test was determined as v50% delta = CV + [vVO2peak - CV)/2], where CV is the critical velocity and vVO2peak the lowest velocity at which peak VO2 occurred. To set the subject's CV, expressed as the slope of a straight line that describes the correlation between swimming distance and time, the record times over three swimming distances were recorded in a 50 m swimming pool. The vVO2peak was measured by means of an incremental test in the swimming flume. Gas exchange was measured by means of a telemetric metabolimeter (K4 RQ, Cosmed, Italy) that was connected to a snorkel. The slow component was found in all subjects, with a mean (SD) value of 239 (194) mlO2.min-1. Therefore, although front crawl swimming is fundamentally different from both running and cycling, it appears that it also incurs a VO2 slow component. The origin of this phenomenon, however, is even more uncertain than for the other sport disciplines.

Genes and olympic performance: a co-twin study.

An Olympic gold medalist in a 20 km competitive walking race and his identical twin brother, also an Olympic athlete in the same event but with inferior performance, were tested in order to obtain some further insight into the relative importance of genetic factors in modulating athletic excellence. Both twins had undergone the same strenuous, long-term training for 19 years since the age of 15 under the guidance of the same coach. An assessment of their bio-behavioural profiles at 40 years of age, i. e. 7 years after they ceased training, revealed that intrapair differences were negligible in physiological attributes but divergent in personality traits measured. Respective values for the Olympic winner and his identical counterpart were as follows: Body mass index 23.2 and 22.7, cardiac mass index 85.4 and 84.4 g x m2, squatjumping 25.3 and 27.3 cm, VO2 at running speed 9 km x h(-1) 33.1 and 33.6 ml x kg(-1) x min(-1), VO2 max 57.1 and 58.6 ml x kg(-1) x min(-1) (72.5ml x kg(-1) x min(-1) for the Olympic winner at age 22 yrs), reaction to anger 97 and 9 and anger expression 2 and 76 in percentile of the State-Trait Anger Expression Inventory. Findings suggest that although genetic constitution and years of physical training are prerequisites for making an Olympic athlete, success may be largely influenced by personality traits.

Energetics of best performances in track cycling.

VO2max and best performance times (BPTs) obtained during maximal voluntary trials over 1, 2, 5, and 10 km from a stationary start were assessed in 10 elite cyclists. Steady-state VO2 and peak blood lactate concentration ([La]b) were also determined in the same subjects pedaling on a track at constant submaximal speeds. The energy cost of cycling (Cc, J.m-1) was calculated as the ratio of VO2, corrected for glycolytic energy production and expressed in W, to v (m.s-1). Individual relationships between Cc and v were described by: Cc = Ccrr + k1 v2 where Ccrr is the energy spent against friction and k1 v2 is that spent against drag. Overall energy cost of cycling (Cctot) was obtained, adding to Cc the energy spent to accelerate the total moving mass from a stationary start. Individual theoretical BPTs were then calculated and compared with the actual ones as follows. The maximal metabolic power sustained at a constant level by a given subject (Emax, W) is a known function of the exhaustion time (te). It depends on his VO2max and maximal anaerobic capacity; it was obtained from individual VO2max and [La]b values. The metabolic power (Ec, W) necessary to cover any given distance (d) is a known function of the performance time over d (td); it is given by Ec = Cctot v = Cctot d td. For all subjects and distances, the t values solving the equalities Emax F(te) = Ec F(td) were calculated and assumed to yield theoretical BPTs. Calculations showed a fairly good agreement between actual and calculated BPTs with an average ratio of 1.035 +/- 0.058.

Anaerobic contribution to the time to exhaustion at the minimal exercise intensity at which maximal oxygen uptake occurs in elite cyclists, kayakists and swimmers.

Using 23 elite male athletes (8 cyclists, 7 kayakists, and 8 swimmers), the contribution of the anaerobic energy system to the time to exhaustion (t(lim)) at the minimal exercise intensity (speed or power) at which maximal oxygen uptake (VO2max) occurs (IVO2max) was assessed by analysing the relationship between the t(lim) and the accumulated oxygen deficit (AOD). After 10-min warming up at 60% of VO2max, the exercise intensity was increased so that each subject reached his IVO2max in 30 s and then continued at that level until he was exhausted. Pre-tests included a continuous incremental test with 2 min steps for determining the IVO2max and a series of 5-min submaximal intensities to collect the data that would allow the estimation of the energy expenditure at IVO2max. The AOD for the t(lim) exercise was calculated as the difference between the above estimation and the accumulated oxygen uptake. The mean percentage value of energy expenditure covered by anaerobic metabolism was 15.2 [(SD 6)%, range 8.9-24.1] with significant differences between swimmers and kayakists (16.8% vs 11.5%, P < or = 0.05) and cyclists and kayakists (16.4% vs 11.5%, P < or = 0.05). Absolute AOD values ranged from 26.4 ml.kg-1 to 83.6 ml.kg-1 with a mean value of 45.9 (SD 18) ml.kg-1. Considering all the subjects, the t(lim) was found to have a positive and significant correlation with AOD (r = 0.62, P < or = 0.05), and a negative and significant correlation with VO2max (r = -0.46, P < or = 0.05). The data would suggest that the contribution of anaerobic processes during exercise performed at IVO2max should not be ignored when t(lim) is used as a supplementary parameter to evaluate specific adaptation of athletes.

A comparison of time to exhaustion at VO2 max in élite cyclists, kayak paddlers, swimmers and runners.

A recent study has shown the reproducibility of time to exhaustion (time limit: tlim) at the lowest velocity that elicits the maximal oxygen consumption (vVO2 max). The same study found an inverse relationship between this time to exhaustion at vVO2 max and vVO2 max among 38 élite long-distance runners (Billat et al. 1994b). The purpose of the present study was to compare the time to exhaustion at the power output (or velocity) at VO2 max for different values of VO2 max, depending on the type of exercise and not only on the aerobic capacity. The time of exhaustion at vVO2 max (tlim) has been measured among 41 élite (national level) sportsmen: 9 cyclists, 9 kayak paddlers, 9 swimmers and 14 runners using specific ergometers. Velocity or power at VO2 max (vVO2 max) was determined by continuous incremental testing. This protocol had steps of 2 min and increments of 50 W, 30 W, 0.05 m s-1 and 2 km-1 for cyclists, kayak paddlers, swimmers and runners, respectively. One week later, tlim was determined under the same conditions. After a warm-up of 10 min at 60% of their vVO2 max, subjects were concluded (in less than 45 s) to their vVO2 max and then had to sustain it as long as possible until exhaustion. Mean values of vVO2 max and tlim were respectively equal to 419 +/- 49 W (tlim = 222 +/- 91 s), 239 +/- 56 W (tlim = 376 +/- 134 s), 1.46 +/- 0.09 m s-1 (tlim = 287 +/- 160 s) and 22.4 +/- 0.8 km h-1 (tlim = 321 +/- 84 s), for cyclists, kayak paddlers, swimmers and runners. Time to exhaustion at vVO2 max was only significantly different between cycling and kayaking (ANOVA test, p < 0.05). Otherwise, VO2 max (expressed in ml min-1 kg-1) was significantly different between all sports except between cycling and running (p < 0.05). In this study, time to exhaustion at vVO2 max was also inversely related to VO2 max for the entire group of élite sportsmen (r = -0.320, p < 0.05, n = 41). The inverse relationship between VO2 max and tlim at vVO2 max has to be explained, it seems that tlim depends on VO2 max regardless of the type of exercise undertaken.

A new respiratory valve system for measuring oxygen uptake during swimming.

We describe a new respiratory valve system with minimal dead space, which allows measurement of ventilation and oxygen uptake during swimming. The device offers considerable advantages in efficiency and accuracy over current equipment, and can be used in conjunction either with a miniaturized telemetry system for oxygen uptake measurement or with a conventional system. The valve has a low airflow resistance, a small dead space (15 ml), and an electrically operating, closed-circuit pump to remove excess water from the expiratory tube. The external form and the buoyancy of the valve have been hydrostatically and hydrodynamically designed to reduce drag and to ensure a correct mass in the water. To obtain this result a very sophisticated material, carbon fibre, has been utilized. Our studies showed that this respiratory system is ideal for obtaining valid and reliable values of oxygen uptake during swimming, even at high speed and in endurance swimming tests.

Nedocromil sodium in the prevention of exercise-induced bronchospasm in athletes with asthma.

The aim of this study was to determine the efficacy of nedocromil sodium in the prevention of exercise-induced bronchospasm (EIB) in 13 top athletes affected by bronchial asthma. At a dose of 4 mg the drug significantly reduced the fall in FEV1 compared with placebo but not with respect to basal values. In 9 athletes, 4 mg nedocromil sodium produced a good protective effect and reduced the mean fall in FEV1 to 4% with respect to baseline values, while in the remaining 4 subjects, the protective effect was not satisfactory. In these 4 "non responders" 6 mg nedocromil was effective, and in 2 cases induced prolonged bronchodilatation. In conclusion, the effect of nedocromil sodium in the prevention of EIB may be dose-dependent in relation to the degree of bronchial hyperreactivity or to interference of other factors.

The effect of pre-stretch on mechanical efficiency of human skeletal muscle.

The mechanical efficiency of positive work was studied in six subjects performing three different types of exercises. On the first occasion the subjects ran on a motor-driven treadmill at 3.33 m s-1; the second and the third exercises consisted of performing rhythmical vertical jumps for 1 min both in rebound (RJ) and no-rebound (NRJ) conditions. The mechanical efficiency calculated in NRJ, which reflects only the conversion of biochemical energy into mechanical work, was found to be lower than the corresponding observation in RJ, 17.2 vs. 27.8% (P less than 0.001), respectively. These differences could not be explained by only the storage and recoil of elastic energy occurring in RJ compared with NRJ. The calculated extra work delivered 'free' was greater than the potential elastic energy which could be stored within the leg extensor muscles (187 vs. 124 J for each jump, P less than 0.05). It is likely that other factors might be responsible for the extra work found in NRJ. It was suggested that the difference in the length of time to perform positive work between a simple shortening contraction and a stretch-shortening muscular activity could be also responsible for the enhanced efficiency observed in RJ. This suggestion was supported by the high relationship (P less than 0.001) found between the time to perform positive work and the mechanical efficiency measured in jumping and estimated during running.

Relationship between the efficiency of muscular work during jumping and the energetics of running.

The running economy of seventeen athletes was studied during running at a low speed (3.3 m X s-1) on a motor-driven treadmill. The net energetic cost during running expressed in kJ X kg-1 X km-1 was on average 4.06. As expected, a positive relationship was found between the energetic cost and the percentage of fast twitch fibres (r = 0.60, n = 17, p less than 0.01). In addition, the mechanical efficiency during two different series of jumps performed with and without prestretch was measured in thirteen subjects. The effect of prestretch on muscle economy was represented by the ratio between the efficiency of muscular work performed during prestretch jumps and the corresponding value calculated in no prestretch conditions. This ratio demonstrated a statistically significant relationship with energy expenditure during running (r = -0.66, n = 13, P less than 0.01), suggesting that the elastic behaviour of leg extensor muscles is similar in running and jumping if the speeds of muscular contraction during eccentric and concentric work are of similar magnitudes.

Maximal anaerobic (lactic) capacity and power of the horse.

Blood lactate concentrations were determined in 16 horses (three Thoroughbreds, seven Standardbreds and six polo ponies) before and 5 mins after they galloped over distances of 200, 300 and 400 m at maximal speed. The highest net lactate concentration (delta Lamax) of 14 to 15 mmol/litre was attained by the polo ponies and the highest speed by the Thoroughbreds. The maximal rate of lactate production (delta Låmax) was about 35 mmol/litre X min for the polo ponies and 20 to 25 mmol/litre X min for the Standardbreds and the Thoroughbreds. Values for delta Lamax and delta Låmax were similar to those measured in human athletes after exhaustive work. delta Låmax increases with the speed (v) and can be described by the equation delta Lå = a (v-v1), where a is a proportionality constant representing the amount of lactate needed to cover a unit distance and v1 the theoretical speed at which delta Lå = 0 X v1 was highest for the Thoroughbreds and lowest for the polo ponies; this difference could be caused by the effect of training and/or to genetic differences among the different breeds of horses X v1 could be a useful index of the fitness of a horse following a training programme.