Cadence 原意指一個單位時間完成的周期數，在音樂上，自行車等，依然是這個定義。
按理說，人走路的一個周期，是左右腳完成各一次。馬有四隻腳，噠噠噠噠，一個Cadence.
但是，習慣上，人們把一步定義為一隻腳跨一次，那麽大多數人以為一個Cadence就是一步。
但很多搞基礎的，還是認為一個Cadence是一個周期，兩步。
所以，如果你有時看到長跑最佳Cadence是90，不要奇怪。
維基百科的英文版，還是這麽定義的。但中文版似乎是一步算一個周期。
https://en.wikipedia.org/wiki/Cadence_(gait)
Cadence in sports involving running is a measure of speed calculated as the total number of full cycles (of both a right and left foot strike) taken within a given period of time, often expressed in steps per minute or cycles per minute. It is used as a measure of athletic performance.
It is similar to cadence in cycling. In running and racewalking, increasing cadence can be beneficial.[1]
In sports such as weightlifting or bodybuilding, cadence can refer to the speed or time taken to complete a single lift, rather than how many repetitions of a lift are completed.
https://zh.wikipedia.org/zh-cn/%E6%AD%A5%E9%A2%91
步頻指的是單位時間內走動的步數。
