2010-10-07 23:56:27frank

[游泳技巧] 自由式的打水 (flutter kick)

雖然會游泳已經很久了,但是開始練游泳是這幾年的事。

以前總是輕鬆游,但同事安東尼卻設了一個時間標準,1500m自由式要游在31分以內。好不容易在游了兩三年後達到一個討價還價後的32分,代價是雙肘的肌腱炎。也為此休息了兩三年,一直到今年五月(5/18),因為膝蓋疼痛不騎單車後,才又開始游泳復健。

對於沒有肌肉的我而言,一次1500M自由式,又要要求強度,負擔太大了。所以從今年開始游泳以來,都沒有嘗試游1500M自由式。從開開始的每次去游泳只有五六百公尺,到現在每次去都游兩千了。不過只要連續幾次增加強度,手肘或膝蓋就會發出警訊,因此也不太敢向以前那樣放手一搏的游。

游泳是一項技巧要求高於體力的運動,因此速度不會因為年紀增加而大幅滑落。至於技巧,拜 internet 之賜,總可以找到不少有用的資料。 (請參考:[觀念與技巧] 游泳技巧遠較訓練重要)

我在游自由式時,雙腳基本上只有維持身體穩定的作用,因為不會打水。所以要增加速度最快的方法便是讓原本只負責穩定與平衡的雙腿也能產生推力。近來開始練習打水,可是不但練得很累,速度極慢,而且腳掌上蹠骨(metatarsal)連接趾節(phalange)的關節(metatarsal-phalange joint)常有抽筋的感覺或前兆。

我在一個游泳的論壇上看到這樣的post,


Posted Jul 31, 2009 04:36AM

dear friend follow what i have mentioned above and you will reach your goal ,yesterday one of my students ,made the 25 meters flutter kicking in 15 seconds ,he is 11 years old ,and the 50 meters foe(應是for,打字錯誤) 31 seconds ,,good luck
http://www.goswim.tv/forums/2/topics/5956


天啊!那速度真快!我同樣的距離要花這小孩子四到五倍的時間!他的建議是:

There are two keys to correct kicking technique in swimming. Swimmers must point their feet down (pointing in the opposite direction to where they want to go) and they must turn their feet and big toe inwards. Most swimmers will get the first point correct without being shown because it happens naturally during the kick, however the second point is something which needs to be learned.By pointing the feet and big toes inwards (towards the centre line of the body) it increases the area of the feet which is used to generate propulsion and it increases the ankle flex of swimmer during the kicking motion (without needing to increase your ankle flexibility!). The feet and legs should remain ‘relaxed’ throughout the kick as this helps with leg flexibility.

http://www.goswim.tv/forums/2/topics/5956

這顯然很難!我到泳池去試了,沒有多大改善。

後來我在一個中文的網站上發現了類似的建議


# 打到最大靜水量:腳板伸直內八字,往下打水時略滑向身體的中心線,腿向上抬時,腳板放鬆腳尖下指,有如搖櫓的動作,增加推進力。

# 用身體的力量打水,以節省體力:當腿打水時,腰需配合用力。

# 鞭式打水:善用游泳技巧及餘力打水,當打水小腿尚未達身體的中線時,大腿需先抬起,帶動腳尖迅速向下鞭水。

http://www.lifesaving.tw/swim/dy/kick.htm


今天讀到一篇文章才發現,原來打水的效率與腳踝的柔軟度有關。

The amount of leg power swimmers can transfer to the water depends primarily on the forward range of motion of the foot. The farther your foot bends forward the more leg power you will be able to transfer to the water and the farther you will travel with each stroke.......

If your foot flexes to significantly more than 90 degrees, very little knee bend is needed to kick. As the foot kicks against the water, the pressure from the water against the top of the foot keeps the foot flexed forward. The calf muscles need not be used. The blood flow which would have gone to the calf muscles is then free to be used in the upper body. This kick causes very little drag and generates excellent propulsion.

The Flutter Kick: One of Swimming's Mysteries  by Marty Hull
http://www.alexandriamasters.com/articles/flutter.htm


請看索普的雙腳多麼柔軟!打水的動作十分俐落,優美。




難怪那些在上游用課的小朋友一開始都是用浮板練習打水,另外是用蛙鞋除了增加速度,訓練肌力外,也可以增加柔軟度。11-year-old kid不但水阻較小,柔軟度也好,所以能有如此出色的表現!看來得下決心練練柔軟度了。

Jenny and Tony were playing coach and student at swimming pool.    by Frank, Taipei, 2008.6.20