The purpose of pre-exercise screening is not to find reasons to stop people exercising; it is to identify the small number for whom a medical assessment should come first, while getting everybody else moving without delay. That framing is a genuine reversal of older practice and it is the single most examinable idea in this topic. This page is about screening the ordinary adult who wants to become more active, which is a different question from screening a competitive athlete for causes of sudden cardiac death. It covers why the approach changed, how the widely used American College of Sports Medicine screening algorithm works, the tools used in UK practice, and the contraindications that genuinely should stop or delay exercise.
Screening models built on counting cardiovascular risk factors referred very large numbers of people for medical clearance. Those referrals cost time and money, and, more importantly, they created a barrier: told to see a doctor before starting, many people simply never started. Meanwhile the evidence accumulated that exercise is safe for the great majority, that symptoms and known disease discriminate better than simple risk factor counts although serious events can still occur without preceding symptoms, and that the cardiovascular risk associated with exertion falls as a person becomes more active. The conclusion was that excessive referral created cost, delay and an avoidable barrier to physical activity.
A scientific roundtable convened by the American College of Sports Medicine in 2014 therefore produced the model that has shaped practice since 2015, replacing risk factor counting with a symptom-led and activity-led approach. It is a widely used conceptual framework rather than a formal UK national clearance algorithm, and it supplements rather than replaces condition-specific guidance and clinical judgement. UK guidance reaches the same destination from a different direction, stating plainly that the risk of serious adverse events from physical activity is very low, that the benefits outweigh the risks even for most people living with long term conditions, and that perceptions of activity being unsafe for these groups should be actively challenged. Both positions rest on the same underlying point: for the overwhelming majority the dangerous option is remaining inactive.
Four inputs drive the decision, and knowing their precise definitions is what separates a correct answer from a plausible one.
The first is current activity level. Regular exercise participation has a specific definition here: planned, structured physical activity of at least 30 minutes at moderate intensity, on at least three days a week, for at least the past three months. Anything less counts as not currently active. The second is known disease, meaning established cardiovascular, metabolic or renal disease. Cardiovascular includes cardiac, peripheral vascular and cerebrovascular disease, and metabolic here means type 1 or type 2 diabetes. The third is signs or symptoms suggestive of those diseases, at rest or on exertion: ischaemic-sounding chest discomfort, breathlessness at rest or on mild exertion, dizziness or syncope, orthopnoea or paroxysmal nocturnal dyspnoea, ankle swelling, palpitations, intermittent claudication, or unusual fatigue with ordinary activity, alongside signs such as a known murmur or ankle oedema. New or unexplained exertional chest pain, syncope, significant breathlessness or palpitations require clinical assessment, although a single mild or non-specific symptom does not mean stopping all light daily activity. The fourth is the intended intensity, since the threshold for concern is higher for vigorous activity than for light to moderate.
Two outputs are worth memorising. New or unexplained symptoms require medical evaluation in anybody, whatever their activity history, and exercise should be discontinued until that happens. Conversely, someone who is already exercising regularly and has known but stable disease with no symptoms does not need fresh clearance to carry on at their current moderate intensity, though they should seek it before stepping up to vigorous activity. The person who most often needs clearance is the inactive individual with known disease who wants to start.
Two instruments come up repeatedly. The Physical Activity Readiness Questionnaire for Everyone (PAR-Q+) is a widely used international self-completed screening tool. It opens with seven general questions, and a negative response to all of them means the person can become more active without further clearance. A positive response leads to condition-specific follow-up questions and further risk stratification rather than automatic exclusion, and where those are also positive the person is directed either to the associated electronic medical examination pathway or to a qualified professional. It carries an explicit instruction that the questionnaire must be used in full and unmodified, which is a useful illustration of the general rule that altering a validated instrument invalidates it.
The General Practice Physical Activity Questionnaire (GPPAQ) answers a different question. It is a short validated tool for assessing adult activity levels in UK primary care, and it produces a four-level Physical Activity Index: active, moderately active, moderately inactive, and inactive. Anyone below active should be offered a brief intervention to support behaviour change. It is validated for adults aged 16 to 74, so it should not be applied outside that range, and it is intended for assessment rather than for monitoring response to an intervention. Its index deliberately excludes walking, housework, gardening and similar domestic activity, because self-report of these is unreliable, which means the index can understate genuinely useful activity. Recognising that PAR-Q+ screens for safety while GPPAQ measures activity level is a distinction worth holding onto.
Two distinctions matter here and both are commonly muddled. The first is that the formal absolute and relative lists candidates memorise are contraindications to symptom-limited clinical exercise testing, not universal prohibitions on exercise participation. The second is that within those lists, absolute and relative mean genuinely different things.
For clinical exercise testing, absolute contraindications mean the test should not proceed until the underlying situation is treated or resolved. They include myocardial infarction within the preceding two days, unstable angina, uncontrolled symptomatic arrhythmia, symptomatic severe aortic stenosis, acute myocarditis, pericarditis or endocarditis, acute pulmonary embolism or deep vein thrombosis, acute aortic dissection, and acute systemic infection with fever. Relative contraindications to testing mean proceed with modification, closer supervision or specialist advice: known left main stem stenosis, moderate to severe stenotic valve disease, severe resting hypertension, significant tachyarrhythmias or bradyarrhythmias, hypertrophic cardiomyopathy, and high-degree atrioventricular block. None of these carries a single universal status independent of severity, symptoms, treatment and the exercise intended.
For exercise participation the framing is different and more practical. Acute unstable cardiovascular or systemic illness means defer and assess. A severe uncontrolled physiological abnormality, such as markedly raised resting blood pressure, means medical review before structured exercise. Stable disease means an individualised prescription, often with supervision. Myocardial infarction within two days is a testing criterion and must not be read as a general prohibition on early mobilisation, which follows its own post-infarction rehabilitation pathway.
Alongside these sit situations where activity should be deferred or modified rather than reconsidered: an acute febrile illness, poorly controlled diabetes with significant ketones, or a recent unassessed injury, which usually means modifying activity and assessing the affected region rather than stopping everything. Deferral is not the same as contraindication, and framing it that way to the patient keeps the door open. Finally, remember that screening is not a one-off event. Health changes, and the person cleared last year who has developed exertional chest tightness this year needs reassessing regardless of what the original questionnaire said.
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