Developmental changes of the GABA-immunoreactive fibers in the lamprey spinal cord.

The changes in distribution and number of GABA immunoreactive (GABA-ir) fibers from postembryonic stages to adulthood in the lamprey spinal cord white matter were studied by using immunocytochemical techniques. From prolarvae to adult spawning animals there was an increase of the number of GABA-ir fibers. Three phases can be distinguished: (a) from prolarvae to middle size larvae (around 50 mm in body length) an increase in the number of GABA-ir fibers per section is observed. Furthermore, an adult-like pattern of GABA-ir fibers distribution is established during this phase. (b) Then, the number of GABA-ir fibers remains stable until metamorphosis, the end of the larval period. (c) Finally, in young postmetamorphic and adult animals the number of GABA-ir fibers is higher than in larvae. These observations, joined to the changes previously reported in the GABA-ir neurons, indicate that at least parts of the GABA inhibitory component of the spinal locomotor network is reorganized during the lamprey life cycle and it may indicate different inhibitory requirements in the locomotor network.

Blood lactate and heart rate during national and international women's basketball.

AIM: In order to measure game intensity in female basketball players, 2 teams (Olympic National Team - I -and a team at 1(st) National Division - N) were studied for a total of 12 games (10 official competitions and 2 practice games -P). METHODS: Both blood lactate concentration ([La](b)) and mean heart rate (HR) were measured during the games and then compared with a progressive field test where maximal blood lactate (max[La](b)), individual lactate threshold and maximal heart rate (HR max) values were obtained. All different categories (International, National and Practice) and positions (Guard, Forward and Center) were taken into account in this study. RESULTS: Differences (p<0.05) in HR were found between all positions (Guard=185+/-5.9; Forward=175+/-11 and Center=167+/-12 beats x min(-1)) and between the International team and the rest of the categories (International=186+/-6; National=175+/-13 and Practice=170+/-11 beats x min(-1)). The [La](b) differed between the Guard and the other 2 positions (Guard=5.7+/-2.1; Forward=4.2+/-2.1 and Center=3.9+/-2.0 mmol x L(-1)) and between Practice and the rest of the categories (International=5.0+/-2.3; National=5.2+/-2.0 and Practice=2.7+/-1.2 mmol x L(-1)). The game intensity of International players reached 94.6% of their maximum HR value, whereas National players reached 90.8%, this percentage descending to 89.8% during Practice. International games reached the individual lactate threshold at 89.2% of the maximum HR; National games at 88.6%. CONCLUSION: We can conclude that the game intensity of female basketball increases according to the level of competition. It may also differ according to playing position, being greatest in guards. The game intensity at international level surpasses the individual lactate threshold, whereas it reaches a lower level in training games.

The response of sexual and stress hormones of male pro-cyclists during continuous intense competition.

The aim of this study was to compare hormonal changes in plasma total testosterone (T), cortisol (C), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (P) in two world-class teams, both consisting of 9 top male pro-cyclists, during a real sports situation (the 1998 "Vuelta a España", a 3-week multi-stage international cycling competition). Venous blood samples were taken the day before the race (S0), after 1 week (S1), after 2 weeks (S2) and at the end of the race (S3). The S0 T level was significantly lower in the team with more racing days in the previous month. There was a significant basal T decrease (p < 0.05) during the race in comparison with the initial value, in spite of the difference in S0 T level between teams. However, there was no difference between teams in the mean decrease in T level. C decreased significantly between S0 and S1 and between S1 and S2, but not between S2 and S3. There were no differences in P concentration between teams or throughout the study, except for a significant increase between S2 and S3. There were no initial differences in LH nor FSH concentration between the teams, nor at any of the study follow-up times. We conclude that in professional top-level athletes S0 T values depend on the number of competition days of the previous month. We observed a similar decrease in the T levels in both teams, independent of the absolute S0 values. In both teams C decreased during long-lasting cycling competition.

Physiological differences and rating of perceived exertion (RPE) in professional, amateur and young cyclists.

BACKGROUND: The aim of this study is to measure and compare the physiological characteristics and the rating of perceived exertion (RPE) in 72 high level road cyclists of 3 different categories. METHODS: These cyclists were divided in 3 groups according to their age (24 professionals, mean age 26 years, 22 amateurs, 22 years and 26 juniors, 18 years). MEASURES: they carried out a progressive test to exhaustion in a specific cycloergometer, starting with a power output of 100 watts and increasing 50 watts each 4 min. VO2 was measured continuously. At the end of each one of the 4 min steps the subject was asked about his RPE using the 6-20 Borg's scale. RESULTS: Professional cyclists showed a VO2max, VO2 x kg(-1) and a maximum power output significant higher than other groups, while there were no significant differences between amateurs and juniors. VO2 and RPE were significantly different, in all the categories, during high work loads. No significant differences were found between RPE and %VO2max. RPE and heart rate (HR) were significantly different between professionals and juniors. RPE and %HR max were significantly different with low loads, but no with high loads. In the same way, RPE/w and RPE/(w x kg(-1) were significantly different in all categories. CONCLUSIONS: We conclude that professional road cyclists reached a VO2max, VO2max x kg(-1) and a maximum power higher than the other categories; so, therefore, these parameters are good as performance indicators, and RPE is of practical value to prescribe exercise training intensities in each category.

Intensity of exercise during road race pro-cycling competition.

PURPOSE: The aim of this study was to quantify the intensity of competition during two professional bicycle stage races: the Tour de France (Tour) and Vuelta a España (Vuelta). METHODS: The HR responses of 18 world class cyclists were recorded during the races and compared with HR ranges that corresponded to four intensities of exercise that were measured in the laboratory with an incremental test to exhaustion 2 wk before each race. The four intensities were: Anaerobic (AN) over the individual anaerobic threshold, which was over 90% of VO2max; intense aerobic (IA), which was between 70 and 90% of VO2max; moderate aerobic (MA), which was between 50 and 70% of VO2max; and recovery (RE), which was < 50% of VO2max. The stages were divided in individual time trial (ITT), flat, or mountain. RESULTS: The mean HR of the Vuelta and Tour were, respectively, 133.8 +/- 17.9 and 134 +/- 18.6 beats x min(-1). The mean total time of each stage was 269.6 +/- 122 and 259.4 +/- 119.9 min. The mean stage time over IAT was 17.5 +/- 15.7 and 24.7 +/- 26 min; the IA time was 75.2 +/- 47.6 and 79.6 +/- 48.3 min; the MA was 97.2 +/- 57.4 and 89.5 +/- 54.9 min. Finally the RE time was 79.6 +/- 60.5 and 65.4 +/- 69.7 min. The percentage of participation related to total time of the race was, respectively, in the Vuelta and the Tour, 12.99 and 16.8% in AN exercise intensity, 29.5 and 29.2% in IA, 32.4 and 31.9% in MA, and 25.1 and 25.2% in RE. There are no differences in AN time among flat, mountain, and ITT stages in each race, except for the mountain stages in the Tour. CONCLUSION: Cycling is a high intensity sport because approximately 93 min in flat and 123 min in mountain stages were above 70% of VO2max. In addition, the time spent at IAT was roughly 20 min regardless of stage type, suggesting that the anaerobic capacity limits performance.

Importance of wash riding in kayaking training and competition.

PURPOSE: The use of different wash-riding techniques is common during kayak training and competition. Changes in wash-riding positions could imply a different exercise intensity. The aim of this study, therefore, was to quantify the energy savings made when a kayaker is "wash riding." METHODS: Eight male international flat water kayakers, who performed a field test of 2000 m in each of the four wash-riding positions, head (H), right wave (RW), left wave (LW), and end position (V), were studied. The data investigated were: time, stroke rate, blood lactate (BL), heart rate (HR), and rate of perceived exertion (RPE). Under laboratory conditions kayakers performed the same intensity of exercise in a kayak ergometer, and HR, oxygen uptake (VO2), BL, mean power output (W), and RPE were measured. RESULTS: The results show significant differences (P < 0.05) among H, RW/LW, and V. The mean values for BL (P < 0.05) were 4.2, 2.0, 2.2, and 1.5 mmol.L-1, for H, RW, LW, and V, respectively. RPE also revealed differences, with values of 15, 12.6, 12.6, and 9.7 for H, RW, LW, and V, respectively. Mean power output gave values of 190.3 (H), 155.6 (RW and LW), and 129.5 (V) W. HR was different between H and V (172 and 151), while stroke rate was different among the parameters H, RW, and V (93.7, 88.8, and 87.6, respectively). The VO2 in the kayak ergometer test showed a difference between H and V (3.78 and 2.23 L.min-1). CONCLUSIONS: We conclude that "wash riding" involves a saving in energy cost of between 18% and 31.9%, depending on the position. This conclusion is of importance for the quantification and calibration of kayak training and competition.

[Alterations of auriculoventricular valves in single ventricles and similar abnormalities]. / Altérations des valvules auriculo-ventriculaires dans les ventricules uniques et anomalies similaires

The morphologic changes of the atrio-ventricular valve in 30 cases of lone ventricle or similar anomalies have been: 1. Common atrio-ventricular valve (8 cases); 2. Abnormally small left atrio-ventricular valve (15 cases) 3. Parachute-like left atrio-ventricular valve (5 cases); 4. Atresia of one of the atrio-ventricular valves (2 cases); 5. Atrio-ventricular valves corresponding to a tricuspid valve which were bicuspid (6 cases); 6. Accessory valvular orifices (5 cases); 7. Valvular clefts (3 cases); 8. Insufficient valvular tissue (4 cases); 9. Accessory valvular tissue (7 cases); 10. Anomalies of orientation of the anterior in relation with the posterior mitral valve leaflet (7 cases); 11. Peculiar orientation of the valve in relation with the outflow tract, resulting in a "functional overlap" (1 case); 12. Muscle column on the posterior wall of the main ventricular chamber (18 cases); 13. Papillary muscle distribution alterations (29 cases). The embryologic, diagnostic and surgical signification of all these anomalies were considered.