瑜伽，對骨質疏鬆(Osteoporosis)的人有幫助嗎？
When it comes to osteoporosis, yoga has a direct medical application. Bones are strengthened by good diet and sunlight, of course, but that is not enough. Force applied to bones also simulates them to grow stronger. The greater the forces applied to a bone, the greater the bones buildup at the point of the stress.*
瑜珈是骨質疏鬆的復健手段。
充足的營養及日照可以強化骨質，但那遠遠不足。
對骨骼進行重量訓練，可以刺激骨骼長得更密實。加在骨骼上的力量愈大，受力點的骨質更好。
Wolff’s law, articulated almost 120 years ago, states that the architecture of bone, its structure, follows the line of force that bone is subjected to. Since Dr. Wolff’s time, many persuasive studies have shown that different enzymes and biochemical markers of bone synthesis within a bone rise abruptly within twelve seconds of adding stress to it. Yoga is a simple, silent, inexpensive, and nonimpact way of applying that force and directing that application exactly as one intends.*
沃爾夫定律(Wolff’s law)是由十九世紀時德國的解剖學家及外科醫生朱利葉斯•沃爾夫提出的理論，認為健康的人類或動物的骨骼會適應所在部位需承受的負載。
若特定骨骼的負載增加了，骨骼會慢慢的變強壯，來承受該負載。骨中小樑的內在結構會產生適應性的變化，而骨的外層皮層也會隨之變化，因此也有可能使骨骼變粗。
反之亦然，若骨骼負載減少，骨骼也會變細，因為該骨骼的新陳代謝較不需要，而且沒有刺激來產生可以維持骨質量的骨的再建。這種骨密度的減少（骨質缺乏）稱為應力遮蔽（stress shielding），可能出現在髖關節手術（或是植入其他假體）後的情形。骨骼因為其他的假體承受了應力，因此讓骨骼無法承受到正常的應力。(~維基百科)
也有研究顯示，在骨骼𠄘受負載的12秒之內，生成骨質的酵素和相關的生物化學標記會迅速增加。
瑜珈是增加骨骼受力，一種比較溫和的方式。
Exercise has been shown to improve the production of bone without affecting the rate of reabsorption. The vocabulary of bone-muscle cross talk includes several molecular messengers that do just that. Exercise is the ounce of prevention that’s worth way more than its weight in gold. There are steps you can take at any age, but earlier is better. Age five is not too soon. The late teens and even twenties are not too late. But more to the point: exercise is good at any age, and it’s always better than inactivity.
運動有助於加強骨質。養成運動的習慣，愈早愈好，但不管是什麼年紀，運動都有幫助，只要開始永遠不遲。
Many people still believe that weight-bearing is the best, or only, type of exercise for building bones, but that is patently false…One need go no further than his or her arm, wrist, and fingers to find examples of non-weight-bearing bones that may become osteoporotic, but usually din’t in spite of weight-bearing in all but acrobats and yogis…
很多人深信負重是增加骨質密度最好的運動，甚至認為那是唯一有效的方法，而這是不正確的。只要看看我們的手臂、手掌、手指這些非負重骨骼，平常主要是進行平𧗾和拉伸的活動而非負重，但也運作得很好而不會有骨質疏鬆的狀況。
……Wolff’s law…the basis of bone-shaping, states that the architectural strength of a bone develops along the lines of fierce to which that bone is subjected. This makes physiological sense because it means that a bone will develop reinforcement to counter exactly the stresses and strains that is undergoes. This explain why our arms are doing so well and why yogi can help us manage osteoporosis.
根據沃爾夫定律(Wolff’s law)，面對外來的施力，骨骼會自行加強來抵抗外力所產生的壓力和張力。這可以用來解釋，為什麼我們的手臂(的骨骼)可以長得足夠粗壯，縱然平常比較沒有負重的運動，但經常的拉伸(yogi)，也對防止骨質疏鬆是有助益的。
讀後
養成運動的習慣(每週150分鐘中強度運動)，注意均衡營養的攝取，走到戶外曬曬太陽(每天約10-15分鐘)，戒煙不酗酒，有助強化骨骼避免骨質疏鬆。
根據沃爾夫定律，骨骼會因應外力而自我加強，因此負重訓練的效果立竿見影。但骨骼也會隨著拉伸及肌肉的緊縮所產生的力量，而變得更強，所以比較溫和的瑜珈也有幫助。
不管怎樣，結論就是要運動。
人的身體，遵循用進退廢的原則。
多活動，要活就要動。
P.S. 個人覺得，運動除了要養成習慣，其頻率及強度要適中才好。重量訓練可加強肌力和骨骼，是重中之中，有助於避免運動傷害。比較柔和的瑜珈很好，但應在專家指導下實行(尤其是熟齡者)，循序漸進而絕不勉強，以免傷害。
*：Loren Fishman, MD, and Carol Ardman, YOGA for OSTEOPOROSIS, 2025, W. W. Norton & Company, Inc.
2025/12/11 YOGA for OSTEOPOROSIS Damakey
