Yoga

Yoga in its full sense is a philosophical system of which posture is only one limb. What most people mean by it - asana - is nonetheless genuinely good exercise with a reasonable evidence base.

What the evidence supports

Improved flexibility, balance and strength. Meaningful reduction in chronic low back pain, where yoga performs about as well as other exercise therapies and better than no treatment. Modest improvements in anxiety, depression and sleep quality. Better balance in older adults, which matters enormously because falls are a leading cause of serious injury.

Practising sensibly

Learn from a qualified teacher at the start. Most yoga injuries come from forcing a posture the body is not ready for - shoulders, knees, hamstrings and the lower back, in roughly that order. Sharp pain means stop; a stretch is not supposed to be sharp.

Consistency beats intensity. Twenty minutes most days is worth more than two long classes a week.

The posture is not the achievement. Being able to do this at seventy is the achievement.

Talk to a doctor first if

You have glaucoma or retinal problems, uncontrolled high blood pressure, or severe osteoporosis - inversions and some postures need modifying. Also during pregnancy, where several postures should be adapted, and after any recent surgery or injury.

Hot yoga in Indian summer conditions carries a real risk of heat exhaustion. Hydrate, and leave the room if you feel faint.