RESUMO
Sickle cell trait (SCT) is a genetic abnormality affecting the synthesis of normal haemoglobin [Hb] and is the heterozygous form of sickle cell anaemia. The aim of the present study was to compare the ability to repeat maximal cycling sprints (RSA; repeated sprint ability) between SCT carriers (SCT group, n = 7) and a control group with normal haemoglobin [Hb] (n = 7). The two groups performed a 10-s maximal cycling sprint in order to determine the peak power output (P(peak10)). They then performed an RSA test that consisted of five 6-s maximal cycling sprints interspersed with 24 s of passive recovery. For each sprint, the peak power output (P(peak6)) and the work over the 6-s (W6) were calculated. The sum of each W6 developed during the test was considered to be the total work (W(tot)). The decrements over the repeated sprints for P(peak6) (P(6dec)) and W6 (W(6dec)) were also determined. We found no difference in P(peak10), W(tot) and W(6dec) between the two groups. However, the drop in P(peak6) and W6 during the RSA test appeared earlier in the SCT group and the decrease in P(peak6) over the RSA test was greater in the SCT group than in the control group (p < 0.05). In conclusion, we found that: 1) maximal anaerobic performance determined during a single sprint was not altered by SCT, but 2) repeated sprint ability was different in SCT carriers compared with sportsmen with normal Hb.
Assuntos
Ciclismo , Hemoglobina Falciforme/análise , Ácido Láctico/sangue , Resistência Física/fisiologia , Traço Falciforme/fisiopatologia , Adulto , Teste de Esforço , Humanos , Traço Falciforme/sangue , TrabalhoRESUMO
To characterise the anthropometrical and physiological parameters of French West Indian monofin swimmers, seven French West Indian male competitors underwent anthropometrical measurements and physiological testing. The results were analysed in relation with their performances during national and international events (from 50- to 1500-m). We found that both anthropometrical and physiological (aerobic and anaerobic components) factors contributed to the performances of these swimmers. The results demonstrated that certain parameters consistently contributed to the global performance: aerobic parameters (maximal oxygen uptake and the second ventilatory threshold, R (2) = 0.72 and 0.69, respectively), anaerobic parameters (power obtained with the counter-movement jump [R (2) = 0.58] and the force-velocity test [R (2) = 0.54]), leg volume (V1, R (2) = 0.54) and perimeter (P1, R (2) = 0.64), and fat and lean body mass (R (2) = 0.76 and 0.62, respectively). Further studies are needed to compare these determinants of performance in French West Indian and European swimmers and to investigate how they contribute to swimming technique.
Assuntos
Antropometria , Natação/fisiologia , Adolescente , Adulto , Limiar Anaeróbio/fisiologia , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Análise de Regressão , Índias OcidentaisRESUMO
Seven acclimated elite road cyclists were recruited from among the participants in the Tour de Guadeloupe, a 9-day cycle race (D1-D9) held in hot/humid climate (approximately 31 degrees C dry temperature and 76 % relative humidity). Each day of the competition, heart rate (HR) was recorded every 15 s, tympanic temperature (Ttym) was recorded before exercise and immediately at the end of each stage, and body mass loss (BML) was measured by changes in nude body mass at rest and after each stage. Blood lactate concentration [La] was measured at rest and 5 min after each stage. Venous blood samples were collected before the competition and on the 4 th and 8 th days (D4, D8) for hematological and serum determinations and biochemical analyses. No significant differences were found in cardiac, thermoregulatory, or [La] parameters at rest over the 9 days. The subjects spent 31 +/- 6 % of their time below the lactate threshold (LT), 52 +/- 8 % between LT and the onset of blood lactate accumulation (OBLA), and 18 +/- 6 % above OBLA. The increase in Ttym at D3 (0.48 +/- 0.3 degrees C) was significantly lower (p < 0.05) than at D1, D4, D5, and D6. No difference was found for BML between the different stages. Significant increases (p < 0.05) were observed in monocytes at D8 vs. D4 and pre-race values (D0) and in serum Cl-concentration at D4 vs. D0 and D8 (p < 0.05). A significant reduction was observed in mean corpuscular hemoglobin concentration (MCHC) at D8 and D4 vs. D0 (p < 0.01). No difference was found in other blood parameters at D0, D4, or D8. Taken together, these results suggest that a consecutive 9-day cycle competition in hot/humid climate did not alter homeostasis at rest in acclimated well-trained cyclists. No major effect of repeated cycling stages on thermoregulatory and blood parameters was observed during the Tour de Guadeloupe. Further research is needed to compare the cardiac adaptations of natives to tropical climate and un-acclimated subjects during long-duration exercise.
Assuntos
Ciclismo/fisiologia , Regulação da Temperatura Corporal/fisiologia , Frequência Cardíaca/fisiologia , Temperatura Alta , Umidade , Clima Tropical , Adulto , Contagem de Células Sanguíneas , Guadalupe , Humanos , Íons/sangue , Ácido Láctico/sangue , MasculinoRESUMO
AIM: The aim of the present study was to determine the effect of tropical climate (i.e., hot and humid) on performance during multiple jump-and-reach tests. METHODS: Fourteen male basketball players volunteered to perform 2 randomized series of jump-and-reach tests, which consisted of a jump-and-reach test every 15 sec for 5 min (21 jump-and-reach tests) in two thermal conditions: tropical (TR, 30.4 degrees C, 70% rh) and thermoneutral (TN, 23.1 degrees C, 53% rh). During each test, lactate concentration [La(-)], tympanic temperature (Tty), sweat rate (SR), heart rate (HR), and performance (height: H) were noted at rest, during exercise and recovery. Two hours of recovery separated the TN and TR tests. RESULTS: There were no significant differences in mean height, maximal height or the kinetics between TN and TR. Both conditions induced an increase in height over time (time effect: p<0.002). There were no significant differences in [La(-)] at rest or during exercise or recovery in the 2 conditions. Both conditions induced an increase in [La(-)] (time effect: p<0.002). There was a tendency toward a higher mean [La(-)] during TR than TN (situation effect, p<0.07). However, compared to resting values, [La(-)] values were significantly increased only in TR and not in TN. Tty, was significantly greater (p<0.001) at rest and during exercise and recovery in TR than in TN. SR and HR were also significantly greater at rest and during exercise and recovery in TR (p<0.001 for SR and HR). CONCLUSION: We conclude that tropical climate affects physiological responses without improving or decreasing performance during successive jump tests.
Assuntos
Basquetebol/fisiologia , Exercício Físico/fisiologia , Clima Tropical , Adulto , Temperatura Corporal/fisiologia , Guadalupe , Frequência Cardíaca/fisiologia , Humanos , Ácido Láctico/sangue , Masculino , Sudorese/fisiologiaRESUMO
BACKGROUND: The aim of the present study was to determine the best jump power equation in the evaluation of elite volleyball players using both the force platform and peak power equations. METHODS: Nine elite volleyball players and nine sedentary subjects performed counter-movement jump tests on a force platform. RESULTS: Peak power and height were greater in the volleyball players than in the sedentary subjects, whatever the method used. The results demonstrated that the peak power values obtained on the force platform and those scored from the equations of Lewis, Harman and Sayers et al. were correlated when the whole sample was taken into account. However, a significant equation x level interaction (p<10(-4)) indicated different behaviour as a function of performance level. In sedentary subjects, peak power was significantly underestimated using the Lewis equation (943+/-162 W; p<10(-4)) and did not differ using both the Harman (3004+/-563 W) and Sayers (3400+/-604 W) equations when compared to the peak power noted with the force platform (3372+/-532 W). In contrast, in volleyball players, peak power was underestimated using the three equations (1246+/-78 W, p<10(-4); 4314+/-216 W, p<0.001; 4607+/-251, p<0.005; for the Lewis, Harman and Sayers equations, respectively, versus 5355+/-522 W for the force platform). CONCLUSIONS: The results of the present study demonstrate the difficulty in choosing the most relevant equation in the jump power calculation.
Assuntos
Ergometria/métodos , Músculo Esquelético/fisiologia , Esportes/fisiologia , Adulto , Fenômenos Biofísicos , Biofísica , Humanos , Masculino , Matemática , Suporte de Carga/fisiologiaRESUMO
The aim of the present study was to assess the performance of subjects with sickle cell trait (SCT) during brief and explosive exercise involving mainly anaerobic metabolism. One hundred and ninety-six black subjects underwent SCT screening, which revealed the presence of 16 subjects with SCT and 180 subjects with normal hemoglobin (HbAA). All subjects performed four tests: 1) a 100-m sprint, 2) a long-jump, 3) a Leger-Boucher shuttle test and 4) a jump-and-reach test. A control group (n = 18) selected from the 180 subjects with HbAA was matched according to the sex, age, weight and height of the SCT subjects (SCTs). The performances of the SCTs (n = 16) were compared with those of the control group. The performances were similar between the SCTs and control group for the sprint test, long-jump and the Leger-Boucher shuttle test. There was, however, a significant difference for the jump-and-reach test between the two groups: the SCTs (i. e., males plus females, and males and females considered separately) reached a significantly greater height (p < 0.05) than the matched subjects of the control group (63.7 +/- 3.6 vs. 58.6 +/- 3.1 cm, 72.3 +/- 3.9 vs. 67.1 +/- 2.4 cm and 52.7 +/- 3.2 vs. 45.3 +/- 2.0 cm for SCTs versus non-SCTs, for the group, the males and the females, respectively). The results of the present study suggest that the performance of brief and explosive exercise may be enhanced by HbS.