Stop and get medical help
If you get chest pain or pressure, feel faint or dizzy, are unusually breathless, or your heart races or beats irregularly during exercise, as our plans advise. The American Heart Association says these need immediate medical evaluation.
Source 34
Call 999 (911 in the US)
For chest pain that comes on suddenly and doesn't go away, feels tight or like squeezing, spreads to your arms, neck, jaw, stomach or back, or comes with sweating, feeling sick, light-headedness or breathlessness; arm pain that comes on suddenly with pressure, heaviness or squeezing across your chest; severe difficulty breathing, or a chest that feels tight or heavy; someone who faints while exercising; palpitations that don't go away, or come with chest pain, shortness of breath or feeling faint; or a headache that starts suddenly and is extremely painful, especially while lifting or straining. The NHS says a bleed on the brain may be more likely when lifting something heavy. Don't drive yourself to A&E.
Sources 36, 37, 38, 39, 40, 41, 42, 43
A headache with effort
Ask for an urgent GP appointment or get help from NHS 111 for a headache that's triggered or made worse by coughing, sneezing, bending down or exercising.
Source 42
Your back
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.
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.
Sources 44, 45
Back pain that needs a GP soon
Ask for an urgent GP appointment or get help from NHS 111 if you have back pain and feel hot, cold, shivery or generally unwell, or have severe pain that starts suddenly or gets worse quickly.
Source 44
A pulled muscle
A sudden sharp pain in your back, side or armpit during a row may be a strained muscle. Get help from NHS 111, or go to an urgent treatment centre (in the US, urgent care), if it's very painful or the pain is getting worse, there's a large amount of swelling or bruising or it's getting worse, it feels very stiff or is difficult to move, it's not feeling any better after treating it yourself, or you also have a very high temperature or feel hot, cold or shivery.
Source 46
Your elbow and grip
A pop or snap with sudden pain at the front of the elbow, especially with bruising, a gap at the front of the elbow or a bulge in the upper arm, can be a torn biceps tendon. Go to an urgent treatment centre or A&E (in the US, urgent care) the same day, and don't wait for it to settle, as our biceps guides say.
Stop if your fingers tingle or go numb: that's a nerve, not a tired muscle, as our grip strength guide says.
Source 38
A hernia
See a GP if you think you have a hernia, a bulge or lump that may get bigger when you strain and smaller when you lie down. Get help from NHS 111 if you have a hernia and pain in or around it, a bloated tummy, you feel or are sick, you're vomiting blood or your vomit looks like coffee grounds, you're constipated, you have a high temperature or feel hot, cold or shivery, or you've suddenly become confused. Call 999 or go to A&E for a femoral hernia (a small lump at the top of your thigh, in your groin) with very bad tummy pain, sickness, being unable to fart or poo, a high temperature or sudden confusion.
The NHS lists lifting heavy weights among the causes of a femoral hernia. After an inguinal hernia repair, avoid heavy lifting or strenuous activity for at least 4 to 6 weeks.
Sources 47, 48, 49
Your shoulder
Ask for an urgent GP appointment or get help from NHS 111 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 or shoulder, an arm or shoulder that's hot or cold to touch, pain after an injury or a fall, severe pain in both shoulders, or feeling feverish or unwell. Go to A&E if, after an injury, you can't move your arm or your shoulder looks out of place or has changed shape. See a GP if shoulder pain is getting worse or hasn't improved after 2 weeks.
Source 50
Sore, or hurt?
Muscle soreness for a day or two after a new or harder session is common and fades. Sharp pain, or pain that builds during a set or lingers into the next day, isn't: swap to an easier version, and see a clinician if it persists, as our plans advise. The NHS says to stop exercising straight away if you feel any pain or become unwell, and to get help from 111 if symptoms worry you or don't go away.
Source 51
Before you start
Speak to your GP first if you haven't exercised for some time or have medical conditions or concerns, as the NHS advises. Get advice before hard or straining work if your blood pressure is uncontrolled (140/90 or higher at a clinic, or 135/85 at home), or you have heart disease or chest pain when you're active, a pacemaker or defibrillator, diabetic eye disease, glaucoma, a hernia, recent eye or tummy surgery, or you're pregnant, as our breathing guide lists.
With controlled high blood pressure, the American Heart Association considers low- to moderate-intensity strength training with proper breathing safe. Breathe out as you lift, as our breathing guide advises.
With a pacemaker or defibrillator, the American Heart Association asks you to check with your doctor before upper-body strength training, because repeated arm movements can damage or dislodge the leads.
Sources 52, 53, 34