Commercial diving · Medical preparation
Prepare for the aerobic-fitness part of your diving medical, with the examiner’s requirements in view.
For candidates and working divers, including people preparing for saturation work. Training and a step-test result do not replace the full fitness-to-dive assessment.
What does “passing” mean for a diving medical?
HSE’s June 2023 MA1 guidance includes Chester Step testing in working-diver medical examinations. The approved medical examiner assesses suitability for exercise and interprets the result alongside the rest of the medical. Its guidance table uses the following bands; these are not a standalone certificate or an international saturation-diving standard.
| Estimated VO₂max, mL/kg/min | How MA1 frames the decision |
|---|---|
| Above 44 | A 12-month certificate may be issued if the other medical findings are satisfactory. |
| 40–44 | Short-duration certification/reassessment or restrictions may apply. The guidance describes specific circumstances for less demanding recreational, media or scientific work. |
| Below 40 | The general guidance is an unfit certificate, with limited individual exceptions just below 40 for specified less demanding work. These exceptions are not a route to assume clearance for saturation work. |
The examiner applies the full guidance to your work and circumstances. Small differences in estimated fitness should not be treated as proof of a meaningful physiological change.
Confirm these details before training for a score
- Confirm that the appointment is with an examiner accepted for your intended work and jurisdiction. For UK diving-at-work medicals, check the HSE AMED route.
- Tell the examiner whether this is entry training, an annual medical, return after illness, surface-supplied work or saturation work.
- Ask which current standards and contractor requirements apply, what records to bring and whether additional investigations are needed.
- Confirm the test method, preparation instructions and any existing restrictions before practising. Do not select a lower assessment step height yourself to obtain a better result.
Extra questions for saturation divers
Keep three decisions separate: your medical certification, the contractor’s mobilisation requirements, and your ongoing ability to perform the work. An acceptable result from a general gym session does not settle any of them.
- Ask the contractor and diving medical team whether they require additional or recent fitness evidence before mobilisation.
- Disclose relevant changes in health since the last medical and follow the examiner’s return-to-work advice.
- Use these plans only as general land-based preparation where appropriate. Training during saturation, and exercise around diving or decompression, require the diving team’s specific procedures.
- Practise general aerobic fitness and controlled strength; do not improvise underwater breath-hold, rescue or weighted-diving drills from an online training plan.
IMCA D 061 addresses medical and physical fitness within diving operations. Use it through the responsible medical and operational team; this guide does not create a new saturation pass threshold.
Choose a suitable preparation plan
For a confirmed Chester Step assessment, use the step adaptation. Build familiarity with the movement and a consistent aerobic routine; arrange supervised familiarisation if the test is new to you.
The 12-week foundation plan starts with a modest workload for adults who meet its entry criteria. The 8-week plan is for adults already exercising consistently and meeting its stronger starting criteria. Both include home/gym strength options, controlled aerobic sessions, recovery rules and printable checklists.
Use the exercise companion to learn the movements. Repeat weeks when recovery or technique is not comfortable. If an appointment is too close, discuss the next steps with the assessor rather than compressing the programme.
These are general training examples, not medical clearance or a validated guarantee of reaching an occupational threshold. Get individual advice if you have symptoms, health concerns, restrictions or are returning after illness or injury.
What to expect and bring
Bring the documents requested by the examiner, previous certification where applicable, medication details, suitable clothing and secure footwear. HSE describes heart-rate monitoring and a graded stepping assessment, and its medical workflow also includes respiratory assessment. The examiner will explain the required sequence and stopping criteria.
Tell the examiner promptly about symptoms or discomfort. An instruction to stop is part of the assessment process; continuing to the final stage does not create a pass. Follow the provider’s specific pre-test instructions.
If the result is low, borderline or unexpectedly high
Ask the AMED or appropriate diving medical examiner to explain the outcome, any restrictions and the review arrangements before making work or mobilisation plans.
Ask for the actual result, test method, whether the test was valid, and the next action. Do not round a borderline estimate up yourself or substitute a watch estimate. If heart-rate readings changed very little or the result seems implausibly high, ask the practitioner to review the input data and interpretation. Read why a small heart-rate rise can create a high estimate.
Agree whether further training, a repeat assessment or medical review is appropriate. Do not book repeated attempts simply to obtain a more favourable number.
Your next step
Choose your preparation route · 12-week foundation plan · 8-week active plan
Book through the employer or medical examiner if they require a nominated service. Our provider directory is accepting applications; it does not yet contain published providers. Confirm acceptance before paying for a test.
Organising assessments? See our Chester service setup guide, CST2 software and practitioner training and competency.
Need a combined setup? Request an organisation proposal for the software, equipment and practitioner preparation your service needs.
Sources and scope
- HSE MA1, June 2023 — exercise testing, paragraphs 52–58 and Table 1; this is a UK working-diver framework.
- HSE certificate of fitness to dive — approved medical examiner and certification route.
- IMCA D 061 — industry guidance on health, medical and physical fitness responsibilities; no additional numeric threshold is inferred here.
Sources checked 19 October 2026. Employer and examiner instructions can change. These pages provide general preparation guidance; they do not award a pass, certification or medical clearance.