Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT 84112-0920, USA.
Med Sci Sports Exerc. 2011 Oct;43(10):1940-7. doi: 10.1249/MSS.0b013e31821b00c5.
Separate authors have reported that knee extension dominates power production during submaximal cycling (SUB(cyc)) and hip extension is the dominant action during maximal cycling (MAX(cyc)). Changes in joint-specific powers across broad ranges of net cycling powers (P(net)) within one group of cyclists have not been reported.
Our purpose was to determine the extent to which ankle, knee, and hip joint actions produced power across a range of P(net) . We hypothesized that relative knee extension power would decrease and relative knee flexion and hip extension powers would increase as P(net) increased.
Eleven cyclists performed SUB(cyc) (250, 400, 550, 700, and 850 W) and MAX(cyc) trials at 90 rpm. Joint-specific powers were calculated and averaged over complete pedal revolutions and over extension and flexion phases. Portions of the cycle spent in extension (duty cycle) were determined for the whole leg and ankle, knee, and hip joints. Relationships of relative joint-specific powers with P(net) were assessed with linear regression analyses.
Absolute ankle, knee, and hip joint-specific powers increased as P(net) increased. Relative knee extension power decreased (r(2) = 0.88, P = 0.01) and knee flexion power increased (r(2) = 0.98, P < 0.001) as P(net) increased. Relative hip extension power was constant across all P(net) . Whole-leg and ankle, knee, and hip joint duty cycle values were greater for MAX(cyc) than for SUB(cyc).
Our data demonstrate that 1) absolute ankle, knee, and hip joint-specific powers substantially increase as a function of increased P(net) , 2) hip extension was the dominant power-producing action during SUB(cyc) and MAX(cyc), 3) knee flexion power becomes relatively more important during high-intensity cycling, and 4) increased duty cycle values represent an important strategy to increase maximum power.
已有作者报道，在亚最大强度的自行车运动（SUB（cyc））中，膝关节伸展主导功率产生，而在最大强度的自行车运动（MAX（cyc））中，髋关节伸展是主要动作。在同一组自行车运动员中，尚未报道过在广泛的净自行车功率（P（net））范围内，关节特异性功率的变化。
我们的目的是确定踝关节、膝关节和髋关节在一系列 P（net）范围内产生功率的程度。我们假设，随着 P（net）的增加，相对膝关节伸展功率会降低，而相对膝关节屈曲和髋关节伸展功率会增加。
11 名自行车运动员以 90rpm 的速度进行 SUB（cyc）（250、400、550、700 和 850W）和 MAX（cyc）试验。计算关节特异性功率，并在完整的踏板旋转和伸展及屈曲阶段平均。确定整个腿部以及踝关节、膝关节和髋关节在伸展（工作周期）中所占的周期部分。使用线性回归分析评估相对关节特异性功率与 P（net）的关系。
绝对踝关节、膝关节和髋关节的特异性功率随 P（net）的增加而增加。随着 P（net）的增加，相对膝关节伸展功率降低（r（2）=0.88，P=0.01），膝关节屈曲功率增加（r（2）=0.98，P<0.001）。相对髋关节伸展功率在所有 P（net）范围内保持不变。与 SUB（cyc）相比，MAX（cyc）的整个腿部和踝关节、膝关节和髋关节的工作周期值更大。
我们的数据表明，1）绝对踝关节、膝关节和髋关节的特异性功率随着 P（net）的增加而显著增加；2）髋关节伸展在 SUB（cyc）和 MAX（cyc）中是主要的功率产生动作；3）在高强度自行车运动中，膝关节屈曲功率变得相对更为重要；4）增加工作周期值是提高最大功率的重要策略。
