探討自行車踩踏單圈的功率變化

The intra-pedal stroke variation of power output

盧海瑩(LU Hai-Ying)

指導教授 ： 相子元

國立臺灣師範大學/運動與休閒學院/運動競技學系/碩士(2021年)

https://doi.org/10.6345/NTNU202100656

摘要

前言：目前功率計都是以平均功率輸出，無法獲得單圈中瞬間的功率變化。若將單圈踩踏分期，可獲得更多踩踏技術或踩踏效率相關的資訊。目的：將單圈功率分成八期，探討分期功率與平均功率之差異，並探討不同齒輪比及踏頻對功率分布的影響。方法：招募12名受試者，以鞋內足壓系統 (Pedar-X system) 及慣性感測器 (IMU)，收取左腳踩踏時的力量及曲柄的角速度變化，並使用三維動作分析系統 (Vicon) 作為踩踏分期並找出有效力，之後計算功率。以兩種齒輪比 (53/11、53/15) 及三種踏頻 (60、75、90 rpm) 隨機試驗。統計方法為以皮爾森積差相關 (PCC) 及Bland Altman比較本實驗踏頻及功率與SRM功率計在不同齒輪比及踏頻下之相關性及一致性。以成對樣本t檢定比較分八期後，各分期功率與平均功率之差異。並以二因子重複量數變異分析，確認兩項因子間 (A因子：齒輪比，B因子：踏頻) 是否有交互作用，並使用Bonferroi法進行事後比較，顯著水準定為α≤.05。結果：計算踏頻及功率與SRM踏頻及功率皆呈顯著正相關。在六種騎乘條件下，只有第二期功率與平均功率未達顯著差異。隨著齒輪比或踏頻增加平均功率與峰值功率皆上升，但峰值功率的變異較大。結論：以平均功率監控踩踏數據無法得知瞬間功率，若將踩踏功率分期，能得知踩踏時的功率分布情形，進而判斷選手的踩踏技術，提供運動訓練、踩踏效率等相關的資訊。

關鍵字

鞋內足壓系統 ； 慣性感測器 ； 功率計 ； 踩踏技術

並列摘要

The power is the most representative output indicator in cycling. Many riders use a power meter to monitor training. However, a power meter can only obtain the mean power, that user can maintain a stable power output during training. But the mean power will ignore the variation of positive impulse and negative impulse. We can’t use a power meter to evaluate the difference in pedaling technique between two riders with same mean power. If divide the power into phase, more information about pedaling technique or pedaling efficiency can be known. The purpose is divide the power in 8 phase, to compare each phase and the mean power. And the influence of different gear ratios and cadences on power distribution. The study recruited 12 participants. A road bike was set on an indoor bike trainers for the pedaling trials with different gear ratios (53/11、53/15) and different cadences (60, 75, 90 rpm). With Pedar-X system and IMU to collect the force and angular velocity in left side when pedaling. The pedaling phase and find the effective force with Vicon, and calculate the power. After collecting the data, use Pearson's Correlation Coefficient and Bland Altman to compare the correlation between the cadence and the power with the SRM in six trials. Paired Sample t-test was used to compare the difference between each phase and the mean power in a cycle. The repeated-measures two-way ANOVA confirm whether there is any interaction between the two factors. The result shows that the cadence and the power with SRM have a significant positive correlation. In six trials, only the second phase don’t have significant differences with the mean power. As the cadence increase, mean power and peak power are increase, but the variation of peak power is larger. In conclusion, monitor pedaling with mean power can’t obtain instant power. The power divide into 8 phase allows users adjust their posture avoid sports injuries. Provide cyclist with training, which can improve the pedaling efficiency or compare the pedaling techniques in different users.

並列關鍵字

Pedar-X system ； IMU ； power meter ； pedaling technique

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