Mechanical demands and pacing profile adopted by elite mountain bikers during different cross-country events / Demandas mecânicas e perfil de ritmo adotado por ciclistas de montanha de elite durante diferentes eventos do cross-country

ABSTRACT Different competitive environments appears to affect the physical demands during the sports competitions. Thus, the aim of this study was to report the mechanical demand and pacing behaviour of twelve male elite mountain bikers on cross-country short track (XCC) and cross-country Olympic (XCO). During both competition, total race time, speed, power output (PO) and cadence (CA) were recorded. As the race time in the XCC is shorter (21.0 ± 0.5 vs 84.0 ± 3.0 min; p<0.01), the average speed (26.6 ± 0.6 vs 17.8 ± 0.6 km/h; p<0.01), PO (365.0 ± 26.7 vs 301.0 ± 26.2 watts; p<0.01) and CA (81.2 ± 4.7 vs 77.4 ± 4.3 rev∙min−1; p=0.01) were higher than the XCO. While a variable pacing was adopted during XCC, a positive profile was adopted in XCO. In addition, athletes adopted a more conservative starting pace during XCC (below average race speed) but a faster start during XCO (above average race speed). These findings demonstrated that mechanical parameters and pacing profile adopted by cyclists are different between XCC and XCO. Therefore, mountain bikers and coaches must develop specific strategy and training methods in order to obtain success in each competition.

RESUMO Diferentes ambientes competitivos parecem afetar as demandas físicas durante as competições esportivas. Assim, o objetivo deste estudo foi reportar as demandas mecânicas e o comportamento do pacing de doze homens ciclistas de montanha da categoria elite durante o cross-country de pista curta (XCC) e o cross-country Olímpico (XCO). Durante ambas as competições, o tempo total de corrida, velocidade, potência (PO) e cadência (CA) foram gravados. Como o tempo de prova do XCC é menor (21,0±0,5 vs 84,0±3,0 min; p<0,01), a velocidade média (26,6±0,6 vs 17,8±0,6 km/h; p<0,01), PO (365,0±26,7 vs 301,0±26,2 watts; p<0,01) e CA (81,2±4,7 vs 77,4±4,3 rev∙min−1; p=0,01) foram maiores que no XCO. Enquanto um ritmo variável foi adotado no XCC, um perfil positivo foi adotado no XCO. Além disso, os atletas adotaram um ritmo inicial mais conservador durante o XCC (abaixo da velocidade média da prova), mas um início mais rápido durante o XCO (velocidade acima da média da prova). Esses achados demonstraram que os parâmetros mecânicos e o ritmo adotados pelos ciclistas são diferentes entre o XCC e XCO. Portanto, ciclistas e treinadores devem desenvolver estratégias e métodos de treinamento específicos para obter sucesso em cada competição.

Reliability and sensitivity of countermovement jump-derived variables in detecting different fatigue levels / Reprodutibilidade e sensibilidade das variáveis derivadas do salto com contra movimento na detecção de diferentes níveis de fadiga

ABSTRACT The aim was to verify the reliability and sensitivity of countermovement jump (CMJ) derived variables in detecting small, moderate and large changes and whether the capacity of CMJ-derived variables in detecting fatigue is dependent of the volume of the fatiguing exercise. Seventeen physically active men performed two fatigue protocols, on separate weeks, composed by continuous vertical jumps: short protocol (7 x 10 jumps) and long protocol (14 x 10 jumps). Jump height (JH), power output (PO), impulse (IMP) and vertical stiffness (KVERT) were measured during CMJ prior to and immediately after the fatigue protocols. Intraclass coefficient correlation, typical error, smallest worthwhile change and magnitude-based inference were analyzed. PO and JH presented excellent reliability and good sensitivity to detect small and medium changes, respectively. Negative effects of fatigue could be detected most likely by PO, regardless of fatiguing exercise volume. JH and IMP seem to be affected only after long protocol and KVERT only after short protocol. In conclusion, PO (peak and mean) is the better marker in CMJ with excellent reliability and sensibility, which allows detect even the small effects and differentiate the fatigue levels.

RESUMO O objetivo foi verificar a reprodutibilidade e a sensibilidade de variáveis derivadas do salto com contra movimento (CMJ) na detecção de pequenas, moderadas e grandes alterações e se a capacidade das variáveis em detectar fadiga é dependente do volume do exercício fatigante. Dezessete homens fisicamente ativos realizaram dois protocolos de fadiga, em semanas separadas, compostos por saltos verticais contínuos: protocolo curto (7 x 10 saltos) e protocolo longo (14 x 10 saltos). A altura do salto (JH), a potência (PO), o impulso (IMP) e a rigidez vertical (KVERT) foram mensurados durante o CMJ antes e imediatamente após os protocolos de fadiga. Foram avaliados o coeficiente de correlação intraclasse, erro típico de medida, mínima mudança valiosa e magnitude baseada em inferência. PO e JH apresentaram excelente reprodutibilidade e boa sensibilidade para detectar pequenas e médias alterações, respectivamente. Os efeitos da fadiga podem ser detectados mais provavelmente pela PO, independentemente do volume de exercício fatigante. JH e IMP parecem ser afetados somente após protocolo longo e KVERT somente após protocolo curto. Em conclusão, PO (pico e média) é o um marcador melhor durante o CMJ com excelente reprodutibilidade e sensibilidade, o que permite detectar até mesmo pequenos efeitos e diferenciar níveis de fadiga.

Effect of exercise bike cadence and loads on pedaling force and lower extremity EMG / 医用生物力学

Objective To compare the pedaling force and lower extremity electromyography (EMG) with different cadences (60, 75, 90 r/min) and diverse cycling intensities (50%, 65%, 80% POV) and study the different influence on exerciser's pedaling force and lower extremity EMG. Methods Twelve healthy males participated in this study, and underwent two stages. In stage 1 the power output test at VO2max (POV) was got by cycle ergometer. In stage 2, nine conditions (3 kinds of intensities × 3 kinds of cadences) were completed respectively by using counter-balance design to record the changes for their pedaling force and lower extremity EMG. Results The negative pedaling work was significantly increased with the cadence increasing, and the appearing time of the peak pedaling force was significantly shifted forward in the cycle. When the crank angle was at 270°, the average increase of the pedaling force with the cadence increasing could obtain 1.84 times higher. In general, the firing rate of lower extremity muscular activation would be increased with the cadence increasing. Conclusions The cadence has greater effect on the pedaling force and lower extremity EMG. The tendency of pedaling force was shifted forward and the pattern of pedaling force became smoother with the cadence increasing. There are no significant differences among the diverse intensities. Based on the pedaling efficiency in this study, the optimal cadence for untrained people should be 60 r/min.

Left and right ventricular power: outputs are the strongest hemodynamic correlates to allow identification of acute responders to vasodilator treatment in idiopathic pulmonary arterial hypertension / El poder del ventrículo derecho y del izquierdo: son parámetros hemodinámicos que correlacionan con la posibilidad de ser respondedor durante el reto agudo con vasodilatadores en la hipertensión arterial pulmonar idiopática

Introduction: Despite the prognostic importance of traditionally derived measurements, the significance of right heart catheterization (RHC) remains controversial. Thus, a continued search for hemodynamic markers that define better responsive patients is required. Since, right ventricular failure is the most fatal pathway, right (RVPO) and left (LVPO) ventricular power output are parameters that could provide input for a better understanding of the hemodynamics involved in idiopathic pulmonary artery hypertension (IPAH). Method: We retrospectively analyzed how demographics and outcome correlate with hemodynamics to identify responders among IPAH patients. Results: Ninety patients fulfilled the following criteria for inclusion in this study: (1) complete RHC at baseline; (2) an acute evaluation for vasodilators (AEFV, including a positive response, that is, an increase in CO, a decrease in both mPAP and pulmonary vascular resistance ≥ 20% from baseline, respectively); and (3) a long-term follow-up under accepted IPAH treatments. If RVPO decreased (p < 0.001) and LVPO increased (p < 0.012) during AEFV, it is considered that these findings reinforce our ability to identify responders; that is, patients that remained as responders after 6.4 ± 3 years under nifedipine treatment (37.7% of the studied IPAH population). After multivariate analysis, age, RVPO, and LVPO remained as independent variables (OR = 0.927, 95%CI: 0.87-0.98, p = 0.01; OR = 0.114, 95%CI: 0.00-0.91, p = 0.045; and OR = 171.5, 95% CI: 5.3-549, p = 0.004, respectively) when estimating the probability of being a responder. On this basis, an equation was derived to identify responders among IPAH patients, where the probability of being a responder = 1.0196-0.0631 (age) - 4.7693 (RVPO) + 3.8152 (LVPO), ROC: 0.76, 95% CI: 0.63-0.89; p = 0.001. Conclusion:based on the proposed equation, LVPO and RVPO could be used for the identification of responders among IPAH patients.

Introducción: A pesar de la importancia y del significado pronóstico que tienen las mediciones directas y las derivadas del cateterismo cardiaco derecho, éstas permanecen hasta el día de hoy en el terreno académico de la controversia. Por lo tanto, se requiere la continua búsqueda de marcadores hemodinámicos para estratificar a los enfermos con hipertensión arterial pulmonar idiopática. Particularmente, cuando la disfunción contráctil del ventrículo derecho es la vía final más común de esta patología. En esta circunstancia, la determinación del poder del ventrículo derecho y del ventrículo izquierdo representa parámetros que pudieran ser de utilidad para lograr un mejor entendimiento en la hemodinámica de la hipertensión arterial pulmonar idiopática. Método: De manera retrospectiva, analizamos los aspectos demográficos, los hemodinámicos y la sobrevivencia, y si éstos se vieron asociados a la posibilidad de ser enfermos respondedores entre los portadores de hipertensión arterial pulmonar idiopática. Resultados: Noventa enfermos llenaron los siguientes criterios para ser incluidos en el estudio: 1. Contar con cateterismo cardiaco derecho basal; 2. Tener valoración aguda con adenosina, en donde quedó definida una respuesta "positiva aguda" como: aumento del gasto cardíaco, disminución de la presión arterial pulmonar media y de la resistencia vascular pulmonar calculada (≥ 20% de la basal, respectivamente) y; 3. Contar con un seguimiento a largo plazo bajo la influencia de los tratamientos modernos aceptados para enfermos con hipertensión arterial pulmonar idiopática. Sí, el poder del ventrículo derecho disminuyó (p < 0.001) y el poder ventrículo izquierdo aumentó (p < 0.012) durante el reto vasodilatador agudo se consideró que éstos hallazgos reforzaban la habilidad para detectar a los sujetos respondedores con hipertensión arterial pulmonar idiopática; población de enfermos que guardó ese comportamiento hemodinámico durante 6.4 ± 3 años bajo la influencia de nifedipina (37% de la totalidad de la población con hipertensión arterial pulmonar idiopática). Después de efectuar un análisis multivariado, la edad, el poder del ventrículo derecho y del ventrículo izquierdo permanecieron como variables independientes (OR = 0.927, 95%IC: 0.87-0.98, p = 0.01; OR = 0.114, 95%IC: 0.00-0.91, p = 0.045; y OR = 171.5, 95%IC: 5.3-549, p = 0.004, respectivamente) para ser considerados "respondedores". Como resultado, se derivó una ecuación donde la probabilidad de ser respondedor = 1.0196-0.0631 (edad) - 4.7693 (poder del ventrículo derecho) + 3.8152 (poder del ventrículo izquierdo), ROC: 0.76, 95%CI: 0.63 - 0.89; p = 0.001. Conclusión: Con fundamento en los hallazgos de este estudio, la ecuación propuesta, el poder del ventrículo derecho y el ventrículo izquierdo pueden ser utilizados para identificar "respondedores" entre los enfermos con hipertensión arterial pulmonar idiopática.

Maximal power output during incremental exercise by resistance and endurance trained athletes.

This study was aimed at comparing the maximal power output by resistance trained and endurance trained athletes during incremental exercise. Thirty male athletes who received resistance training (Group I) and thirty male athletes of similar age group who received endurance training (Group II) for a period of more than 1 year were chosen for the study. Physical parameters were measured and exercise stress testing was done on a cycle ergometer with a portable gas analyzing system. The maximal progressive incremental cycle ergometer power output at peak exercise and carbon dioxide production at VO2max were measured. Highly significant (P<0.001) differences existed in values of maximal power output and carbon dioxide production at VO2max for group I and group II. The higher power displayed by group I when compared to group II could be due to variations in adaptations that happen in them due to different types of training. Similar studies could serve as a biofeedback and perk up the athlete’s performance.

THE OPTIMUM INTENSITY AND MODE OF COOLING DOWN PROCEDURES AFTER POST REPETITIVE INTERMITTENT HIGH-INTENSITY EXERCISE / 体力科学

The purpose of this study was to compare the effects derived from different modes of active cooling down procedures post repetitive intermittent high-intensity exercise. Seven Japanese male swimmers underwent repetitive 3 bouts of Wingate anaerobic tests on the 1^st day and another Wingate on the following 2^nd day. In each 3 intervals and post all the Wingate testing on the 2^nd day, the participants performed a cooling down randomly chosen from 3 different intensities of 10-min bike-riding and a 10-min static stretching. As to muscle power outputs and emotional conditions, the optimum cooling down intensities were observed at 80% ventilatoly threshold (VT) after the 1^st set and 60% VT level after the 2^nd set. Effective intensities of blood lactate removal rate were observed at 60% and 80% VT level. Thus, the optimum cooling down post repetitive intermittent high-intensity exercise could be dynamic bike-riding at 60% or 80% VT level.

Effects of off-season training on anaerobic power and muscle thickness of varsity male rowers / 体力科学

The purpose of this study was to examine the effects of off-season training on the anaerobic power output and muscle thickness of male varsity rowers. 23 rowers participated in this study. Four all-out cycle ergometer work tests lasting 7 and 40 seconds were used to estimate anaerobic alactic power (AAP) and anaerobic lactic power (ALP) with leg (pedaling) and arm (cranking) exercises. AAP was computed as the highest power output during 7 seconds and ALP was obtained as the mean power output during 40 seconds. Muscle thickness was measured by B-mode ultrasonography at 11 sites on the body. There were significant differences between before and after off-season training in AAP (cranking : 8.4±1.00 vs 9.2±1.10W /kg, p<0.001, pedaling: 14.4± 1.10 vs 15.0±1.00 W/kg, p<0.001) and ALP (cranking : 5.2±0.42 vs 5.5±1.20W/kg, p<0.001, pedaling: 10.1±0.62 vs 9.5±2.10 W/kg, n, s.) . Muscle thickness increased significantly as a result of off-season training at sites on the biceps, triceps, pectoralis major, subscaplar and hamstrings. Similarly, there were significant differences in estimated muscle cross-sectional area (MCSA) on sites on the elbow flexor (20.6±2.6 vs 22.1±1.8cm<SUP>2</SUP>, p< 0.01), elbow extensor (25.3 ±4.8 vs 28.6±4.2cm<SUP>2</SUP>, p<0.001) and knee flexor (71.1±5.8 vs 74.3±5.2cm<SUP>2</SUP>, p<0.01) . The main training program in the off-season consisted of resistance training of the whole body. The high intensity training, used by male varsity rowers during off-season training, increased arm AAP, leg AAP, arm ALP and muscle thickness of the upper body ; but there was no difference in leg ALP and knee extensor muscle. It was suggested that improvements in leg ALP and knee extensor muscle are necessary to during the off-season training program of male varsity rowers.

The explosive leg extensor power output and its evaluation with the function of sex and age / 体力科学

The explosive power output of both legs during extension movement was assessed in 271 male (aged 16-84 yr) and 248 female (aged 16-82 yr) subjects, and the table of evaluation for the value obtained was prepared with the function of sex and age. From a sitting position on a seat, leg extension movement was performed toward the foot plate in the forward, to which the body mass of each subject was applied as a resistance. The reliability of the power measurement was ascertained from the result that the coefficients of variation were under 5 x 10<SUP>-2</SUP> when the power output of 6 subjects was measured once a day for 10 days. On both sexes, the power output per body mass declined linearly with age. The regression equations between age (x) and the power output per body mass (y) were as follows.<BR>male: y=-0.22 x+28.38 (r=.659, n=271; p<0.001)<BR>female: y=-0.13 x+18.36 (r=.583, n=248; p<0.001)<BR>For all groups classified by 10 years, the male indicated greater value than the female in corresponding groups. The ratio of the value for the female relative to that for the male was between 64.8% and 72, 0%. These results suggested that the power output for the male decreased at a higher rate, and the sex difference of it decreased as the age increased.

Comparative Measurement of Skin Surface Hydration Using a Hydrometer and Corneometer / 대한피부과학회지

BACKGROUND: Hydration, the water content of the stratum corneum, is an important factor in both the appearance and the barrier function of the skin. Many non-invasive methods have been developed in order to assesa the hydration state of the skin and the effect of various moisturizers. The hydrometer and carneometer are commercially available instruments which are widely used in dermatologic research. OBJECTIVE: Our purpose was to compare the measuring usefulnes of both instruments on normal subjects with a wide range of hydration states of the hornylayer. METHODS: We measured the conductance with the hydrometer and the capacitance with the corneometer in various hydrating eonditions and compared both insruments. RESULTS: Conductance had a non linear correlation with capacita ice. Capacitance measured with the corneometer had a high sensitivity to moisture in a wide range of hydration levels. On the other hand, conductance guaged with the hydrometer showed a few sensitivity to moisture at a low level. When the hydretion level was measured after a moiturizer was added, 10 % urea cream showed a sharp increase by 256% in terms of conductanae, and H-base by 97.8%. Mineral oil decreased by 41.5% and petrolatum by 62% respectively. On the other hand, when measured in terms of capacitance under the same conditions as above, 38.9 increase in 10% urea cream, 19.3% increase in H-base, 20% decrease in mineral oil, and 43.5 % decrease in petrolatum were reported. Conductance showed a higher hygroscopicity and a lower water holding capacity than capacitance did. When the measurement of the moisture level iri virious parts of the human body is performed, the corneometer provided us with more stable alies than the hydrometer. While the hydrometer can not the available and appropriate under the condition of insulation, the corneometer can measure moisture levels even down at the depth of 250mm. When measured after the oily surface of the forehead was cleansed with soft tissue, conductance and capacitance revealed higher values of moisture levels than before the eleanin. However, there is no statistical significance in these values. CONCLUSION: The hydrometer is a more appropriate tool for the measurement of moisture at a high level, and the corneometer at a low moisture level. The hydrcmeter is a more sensitive method of measuring the increase and the decrease in the moisture level.

Comparative Measurement of Skin Surface Hydration Using a Hydrometer and Corneometer / 대한피부과학회지

BACKGROUND: Hydration, the water content of the stratum corneum, is an important factor in both the appearance and the barrier function of the skin. Many non-invasive methods have been developed in order to assesa the hydration state of the skin and the effect of various moisturizers. The hydrometer and carneometer are commercially available instruments which are widely used in dermatologic research. OBJECTIVE: Our purpose was to compare the measuring usefulnes of both instruments on normal subjects with a wide range of hydration states of the hornylayer. METHODS: We measured the conductance with the hydrometer and the capacitance with the corneometer in various hydrating eonditions and compared both insruments. RESULTS: Conductance had a non linear correlation with capacita ice. Capacitance measured with the corneometer had a high sensitivity to moisture in a wide range of hydration levels. On the other hand, conductance guaged with the hydrometer showed a few sensitivity to moisture at a low level. When the hydretion level was measured after a moiturizer was added, 10 % urea cream showed a sharp increase by 256% in terms of conductanae, and H-base by 97.8%. Mineral oil decreased by 41.5% and petrolatum by 62% respectively. On the other hand, when measured in terms of capacitance under the same conditions as above, 38.9 increase in 10% urea cream, 19.3% increase in H-base, 20% decrease in mineral oil, and 43.5 % decrease in petrolatum were reported. Conductance showed a higher hygroscopicity and a lower water holding capacity than capacitance did. When the measurement of the moisture level iri virious parts of the human body is performed, the corneometer provided us with more stable alies than the hydrometer. While the hydrometer can not the available and appropriate under the condition of insulation, the corneometer can measure moisture levels even down at the depth of 250mm. When measured after the oily surface of the forehead was cleansed with soft tissue, conductance and capacitance revealed higher values of moisture levels than before the eleanin. However, there is no statistical significance in these values. CONCLUSION: The hydrometer is a more appropriate tool for the measurement of moisture at a high level, and the corneometer at a low moisture level. The hydrcmeter is a more sensitive method of measuring the increase and the decrease in the moisture level.