Dave Scott 是六次世界杯鐵人賽(3.86 km 游泳，然後接著騎單車180.25 km，最後再跑一個馬拉松 42.195km)的冠軍。這可以說是對體力與運動效率要求最嚴苛的比賽之一了，因此由他來談如何提升游泳的效率非常有說服力。

一開始關於 Dave Scott 的簡介是摘自維基百科，而內文因為本人拙於中打，就先以英文為之。日後若中打技術進步在來考慮是否用中文改寫。

Dave Scott (born January 4, 1954) is a U.S.triathlete and the first six-time Ironman Triathon World Champion. He won the Ironman Triathlon in Hawaii six times in 1980, 1982, 1983, 1984, 1986, and 1987. Only his rival, Mark Allen, managed to match these six titles eight years later. Scott is also referred to as "The Man." (from wikipedia)

Before I started to coach my friend for crawl strokes, I went back to the pool to practice and observe other swimmers.  Comparing what I observed in the pool with the lecture Dave Scott gave, I did find those common "mistakes" swimmers would make that Dave mentioned in "efficient swimming".

Few points Dave mentioned is really worth of paying attention to,

1. keep the head at neutral position, looking straight down!
2. hand entry out and front aligning with shoulder, entering the water halfway between head and arm's full extension.  4 fingers should enter the water first.
3. extend arm, flex-in the wrist then set-in the elbow.
4. don't drop the elbow.



Though Dave told "extend arms to 170 degrees elbow flexion", I actually extended the arms fully (straighten the arms), and kept full extension as the other arm pulled, enjoyed gliding.  If you checked the first post ([技巧] 自由式的游法 freestyle/front crawl) I put here, you would have found it's employment of "hip driven technique.  Then how about the arms extend to 170 degrees elbow, I tried that myself and found some energy could be saved for extending from 170 degrees to 180, then flexion-in back to 170 degrees because this 10-degree to-and-fro does not produce any momentum.  In addition, if this advice was taken along with employment of "kayak principle" mentioned in previous post about Alexander Popov's technique development ([大師班] 波波夫(Alexander Popov)的自由式), then the speed could be obviously increased.  Accordingly, the swimmers employ more "shoulder-driven technique" by achieving such efficiency and speed increase.

Besides Dave Scott, the educational video that Tomoko HAGIWARA (萩原智子) made is also very inspiring.





It had taken me very long practicing crawl before I could swim easily. However, in order to reinforce the intensity, I set myself a time for swimming crawl as benchmark.  Consequently, I got the tendinitis at elbows.  What a shame!  The elbow tendinitis is well-known as "tennis elbow".  Ironically, I did not get "tennis elbow" when I played tennis heavily, but from swimming which is generally believed to be a good complementary exercises to prevent sports injury.  However, this also demonstrates a great advantage for extending arm to 170 degrees rather than fully extended (180∘).  If the swimmer keep extending his/her arm fully, then pull, when the swimming intensity (you may understand this as "speed") is low, he/she would feel at ease, even present certain elegance.  However, when intensity increased, to push the arm to its limit of RoM (range of motion) is very likely to injure the joints*1, specially when the muscle is not strong enough, nor the joints are flexible enough.  So, to extend arms to 170∘& avoid pushing arm to its limit of RoM, it also avoid sports injury at elbows or shoulder joints.

Remarks:
1. 強推手臂到 Range of Motion 極限的動作很容易造成受傷的，就像是腳踏車椅墊太高了一般。