Lv3. Health_B Yoga

At some point between the 1st and 5th century CE, the Hindu（ヒンドゥー人の）sage（賢人）Patañjali began to codify（体系化する）the ancient, meditative（瞑想の）traditions practiced throughout India. He recorded techniques nearly as old as Indian civilization itself in 196 manuals（説明書）called the Yoga Sutras. These texts defined yoga as the ‘yoking（結びつける）’ or restraining（抑える）of the mind from focusing on external objects in efforts to reach a state of pure consciousness（意識）.

Over time, yoga came to incorporate（取り入れる）physical elements from gymnastics and wrestling. Today, there are a multitude of approaches to modern yoga– though most still maintain the three core elements of Patañjali’s practice: physical posture（姿勢）, breathing exercises, and spiritual（精神の）contemplation（瞑想）. 

This blend of physical and mental exercise is widely believed to have a unique set of health advantages. Such as improving strength and flexibility, boosting heart and lung function, and enhancing psychological well-being. 

But what have contemporary studies shown regarding the benefits of this ancient tradition? Despite attempts by many researchers, it’s tough to make specific claims about yoga’s advantages. Its unique combination of activities makes it difficult to determine which component is producing a specific health benefit. Additionally, yoga studies are often made up of small sample sizes that lack diversity, and the heavy reliance on self-reporting（自己申告）makes results subjective. However, there are some health benefits that have more robust（強い）scientific support than others. 

Let’s start with flexibility and strength. Twisting your body into yoga’s physical postures stretches multiple muscle groups. In the short term, stretching can change the water content of these muscles, ligaments（靭帯）, and tendons（腱）to make them more elastic（伸縮しやすい）. Over time, regular stretching stimulates（刺激する）stem cells which then differentiate（分化する）into new muscle tissue（組織）and other cells that generate elastic collagen（コラーゲン）. 

Frequent stretching also reduces the body’s natural reflex（反射能力）to constrict（抑制する）muscles, improving your pain tolerance（耐性）for feats（離れ業）of flexibility. Researchers haven’t found that any one form of yoga improves flexibility more than another, so the impact of specific postures is unclear. But like other low-impact（衝撃が少ない）exercises, yoga reliably（期待通りに）improves fitness and flexibility in healthy populations. 

The practice has also been shown to be a potentially powerful therapeutic（治癒力のある）tool. In studies involving patients with a variety of musculo-skeletal disorders（筋骨格系障害）, yoga was more helpful at reducing pain and improving mobility（可動性）than other forms of low-impact exercise. Adding yoga to an existing exercise routine can improve strength and flexibility for hard-to-treat conditions like chronic（慢性の） lower back pain, rheumatoid arthritis（関節リウマチ）, and osteoporosis（骨粗しょう症）. 
Yoga’s mix of physical exercise and regimented（厳しく統制された）breathing has proven similarly therapeutic for lung health. Lung diseases like chronic bronchitis（慢性気管支炎）, emphysema（肺気腫）, and asthma（ぜん息）shrink the passageways（通路）that carry oxygen, while weakening the membrane（膜）that brings oxygen into the blood. But breathing exercises like those found in yoga relax the muscles constricting those passageways and improve oxygen diffusion（放散）. Increasing the blood’s oxygen content（含有量）is especially helpful for those with weak heart muscles who have difficulty pumping enough oxygen throughout the body. And for those with healthy hearts, this practice can lower blood pressure and reduce risk factors for cardiovascular disease（心臓血管症）. 

Yoga’s most widely celebrated benefit may be the most difficult to prove: its psychological（心理的な）effects. Despite the long standing association between yoga and psychological well-being, there’s little conclusive（決定的な）evidence on how the practice affects mental health. One of the biggest claims is that yoga improves symptoms（症状）of depression（うつ病）and anxiety disorders. Since diagnosis（診断）of these conditions varies widely as do their origin and severity（症状の重さ）, it’s difficult to quantify（数量で表す）yoga’s impact. However, there is evidence to suggest that yoga can help reduce the symptoms of stress, as well as meditation（瞑想）or relaxation. 

Research on the effects of yoga is still evolving. In the future, we’ll need larger studies, incorporating diverse participants, which can measure yoga’s impact on heart attacks（心臓発作）, cancer rates, cognitive（認知の）function and more. But for now, yoga can continue its ancient tradition as a way to exercise, reflect, and relax.