Pole Length Influences Performance During On-Snow Skating in Female Cross-Country Skiers.

The purpose of this study was to examine the effect of pole length on performance and technique selection during a simulated skating cross-country (XC) skiing competition on snow in female XC skiers. Methods Nine female XC skiers and biathletes (VO2max 63.6 ± 6.2 mL/min/kg, age 22.9 ± 3.5 years, body height 1.69 ± 0.1 m and body mass 60.8 ± 4.6 kg) completed two 5-km skating time-trail with maximal effort. The athletes had a minimum 4.5 h of rest between the two races, which were performed in a random order: one with self-selected poles (89.0% ± 0.6% of body height) and one with 7.5 cm increased pole length (94.0% ± 0.5% of body height). Speed in set terrain sections was determined and the selection of sub-technique was self-reported immediately after each race based on a detailed review of the entire track. Results Skiers performed on average 7.1 ± 7.1 s (P = 0.029) faster with the long poles, with this difference occurring during the first 200 m and in the uphill parts of the track, in which ~ 5% more G3 and ~ 5% fewer G2 sub-techniques were chosen (both P < 0.05). The rating of perceived exertion was 1 ± 0.9 point lower (P = 0.04) and skiing technique was perceived to be ~ 1.2 ± 1.5 points better with long poles (P = 0.038), while the physiological responses (i.e., peak and average heart rate, and blood lactate concentration) did not differ between trials. Conclusion In conclusion, poles 7.5 cm longer than self-selected ones improved performance in skating, by enhancing speed in the initial phase (first 200 m) and in the uphill section of the track. In addition, the longer poles induced more use of the G3 skating sub-technique

Pole Length Influences Performance During On-Snow Skating in Female Cross-Country Skiers.

Purpose The purpose of this study was to examine the efect of pole length on performance and technique selection during a simulated skating cross-country (XC) skiing competition on snow in female XC skiers. Methods Nine female XC skiers and biathletes (VO2max 63.6±6.2 mL/min/kg, age 22.9±3.5 years, body height 1.69±0.1 m and body mass 60.8±4.6 kg) completed two 5-km skating time-trail with maximal efort. The athletes had a minimum 4.5 h of rest between the two races, which were performed in a random order: one with self-selected poles (89.0%±0.6% of body height) and one with 7.5 cm increased pole length (94.0%±0.5% of body height). Speed in set terrain sections was determined and the selection of sub-technique was self-reported immediately after each race based on a detailed review of the entire track. Results Skiers performed on average 7.1±7.1 s (P=0.029) faster with the long poles, with this diference occurring during the frst 200 m and in the uphill parts of the track, in which~5% more G3 and ~5% fewer G2 sub-techniques were chosen (both P<0.05). The rating of perceived exertion was 1±0.9 point lower (P=0.04) and skiing technique was perceived to be~1.2±1.5 points better with long poles (P=0.038), while the physiological responses (i.e., peak and average heart rate, and blood lactate concentration) did not difer between trials. Conclusion In conclusion, poles 7.5 cm longer than self-selected ones improved performance in skating, by enhancing speed in the initial phase (frst 200 m) and in the uphill section of the track. In addition, the longer poles induced more use of the G3 skating sub-technique

Análise do rendimento no primeiro serviço em tenistas de competição sob o efeito de um escoamento aerodinâmico induzido

O presente estudo analisou as variáveis de produto no serviço de tênis em 12 jogadores experientes, quando constrangidos com um escoamento aerodinâmico induzido (EAI) produzido por um ventilador industrial. Para o cálculo da exatidão do serviço, recorreu-se a uma análise 2D. A velocidade de saída da bola foi medida através de um radar. Os jogadores realizaram 100 serviços à máxima velocidade e para o ponto de interseção da linha central e linha de serviço. Os resultados não evidenciam diferenças estatisticamente significativas na exatidão e precisão entre a condição de controlo e as quatro condições com EAI. Na variável velocidade de serviço verificaram-se diferenças significativas em seis participantes. Na relação entre a velocidade e a exatidão constatou-se a existência de correlações negativas e estatisticamente significativas, nas condições EAI1; EAI3 e EAI aleatório. Os jogadores apresentaram uma menor exatidão e precisão em profundidade e maior na direção do serviço.Este estudio analizó las variables del producto en el servicio de tenis en 12 jugadores expertos, cuando se les aplica un flujo aerodinámico inducido (EAI) mediante un ventilador industrial. Se calculó la precisión del servicio aplicando un análisis 2D. La velocidad de salida de la bola fue medida con un radar. Los sujetos realizaron 100 servicios a máxima velocidad hacia la línea de intersección entre la línea central y de servicio. Los resultados no muestran diferencias significativas en la exactitud y precisión entre la condición de control y las cuatro condiciones con EAI. En la variable de velocidad del servicio se encontraron diferencias significativas en 6 participantes. Se hallaron correlaciones negativas y significativas entre la velocidad y la precisión entre las condiciones EAI1; EAI3 y EAI aleatorio. Los jugadores presentaron una menor exactitud y precisión en profundidad y mayor en la dirección del servicio.This study analysed the product variables on the tennis serve of 12 experienced players, when constrained by an induced streamlined flow (EAI), delivered by an industrial ventilator. In order to obtain the serve accuracy, we use 2D analysis. Moreover, the ball's speed was measured by radar. The players performed 100 services at maximum speed and to the intersection point between the central and the service lines. The results showed no statistically significant changes in accuracy and precision between the control condition and the four EAI conditions. The results also showed prominent statistical changes in the serve speed for 6 among the 12 players. Concerning to the relation between the serve's speed and the accuracy, the results showed the existence of negative significant correlations for the speeds EA1, EAI3 and for random EAI. Lastly, the players' attempts had narrower accuracy and precision in the depth than in the serve direction