Come down at once
Dizziness, blurred vision or a sudden headache with your head hanging back mean come down at once: case reports link yoga poses that bend the neck far back with reduced blood flow to the back of the brain. Repeatedly arching the low back to its limit is a recognised risk factor for stress fractures in the lower vertebrae of young athletes, so low back pain that lingers after backbends needs checking. With a history of shoulder dislocation, choose bridge pose instead.
Source 22
Call 999 or go to A&E: cauda equina signs
Call 999 or go to A&E: loss of feeling or numbness around the genitals or bottom, new trouble peeing or controlling your bladder or bowels, changes in genital sensation during sex or problems with erections or orgasm, or pain, tingling, weakness or numbness in both legs. These are signs of cauda equina syndrome, which needs treating in hospital urgently. Don't drive yourself.
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Pain spreading down a leg
See a GP if pain spreading down a leg hasn't improved after a few weeks of home treatment, is getting worse or stops your normal activities. Sciatica on both sides, or weakness or numbness in both legs that's severe or getting worse, is a 999 call or a trip to A&E.
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During and after practice
Stop straight away if you feel any pain or become unwell, the NHS says, and contact 111 if your symptoms worry you or don't go away.
Pain you'd call mild to moderate, no more than about 5 out of 10, that settles within an hour or so, with your back no worse the next morning, is acceptable; if it is worse, do less next time (fewer reps, a smaller range, a lighter load), not nothing. Stop or shrink any movement that sends pain, pins and needles or numbness further down your leg. That's our back pain guides' rule.
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A fall onto your back
Same day (NHS 111): back pain after a new, significant injury in the last 7 days, such as a fall from a height (off a trampoline, a wall or a horse) or a direct blow to the back.
Stop and get help: chest pain, faintness, breathlessness or a racing heart
Stop exercising straight away if you feel any pain or become unwell. Call 999 (911 in the US) for chest pain that doesn't go away or spreads to your arm, neck, jaw, stomach or back, chest pain with sweating, feeling sick, light-headed or short of breath, fainting while exercising, or a pounding, fluttering or irregular heartbeat with chest pain, breathlessness or feeling faint.
Sources 33, 34, 35, 36
Call 999: a sudden, severe headache
A headache that starts suddenly and is extremely painful, especially while straining, can be a bleed on the brain. A headache brought on or made worse by exercise, coughing or bending down needs an urgent GP appointment or NHS 111 (in the US, your doctor or urgent care).
Sources 37, 38
NHS 111: your wrist
For severe wrist pain, feeling faint, dizzy or sick from the pain, a snap, grinding or popping noise at the time of an injury, a wrist you can't move or hold things with, a wrist that has changed shape or colour, a very painful, hot or red lump, or lost feeling in your hand (in the US, urgent care). See a GP if wrist pain hasn't improved after 2 weeks.
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Urgent GP appointment or NHS 111: your shoulder
For sudden or very bad shoulder pain, an arm you can't move, a shoulder that has changed shape or is badly swollen, pins and needles that don't go away, no feeling in your arm, an arm that is hot or cold to touch, or pain that started after a fall or injury. See a GP if shoulder pain gets worse or hasn't improved after 2 weeks.
Source 40