The Truth About Diving Fitness and Longevity

That cocktail is why medical screeners in diving care less about how you look on the beach and more about how your cardiovascular system performs when things get busy underwater. Incident analyses by Divers Alert Network (DAN) repeatedly show cardiovascular disease as a major contributor to diving fatalities, particularly in older or deconditioned divers. Many cases also note overweight or obesity where body mass index was recorded.

The good news is that fitness is one of the most modifiable risk factors in our sport. Improve it, and you not only reduce medical risk, you also extend safe bottom time by breathing more efficiently, handling currents with confidence, and surfacing relaxed instead of exhausted.

What “fit to dive” really means

There’s no universal pass mark, but experts from the Undersea and Hyperbaric Medical Society (UHMS) and hyperbaric medicine groups agree on a practical target. Recreational dives can demand short bursts of exertion similar to a hard hill sprint, so a capacity around 10–12 metabolic equivalents (METs) is ideal. That corresponds to a VO₂ max in the low 40s mL·kg⁻¹·min⁻¹ — or the ability to complete sustained moderate-to-hard effort without distress.

Publications in Diving and Hyperbaric Medicine and agency guidance from PADI and BSAC echo this range, though some suggest that earlier targets of 13 METs for all divers overshoot real-world recreational requirements.

Practically speaking, “fit to dive” means being able to swim 400–500 metres without stopping, climb a long flight of stairs while talking, or fin against a mild current for several minutes without your chest pounding.

Ageing, weight, and the pattern seen in accidents

As the global dive community ages, the risk profile shifts. UK incident data and DAN fatality reviews show the average age in diving deaths is now in the mid to late fifties, with cardiovascular problems often initiating the chain of events.

Obesity and metabolic disease frequently appear in reports, correlating with increased cardiac strain and reduced reserve rather than a direct increase in decompression illness. Keeping weight, blood pressure, and blood sugar in check pays back with decades of safer, more enjoyable diving.

High blood pressure, lipids, and the dive boat

Hypertension is common among divers over forty. DAN medical guidance suggests resting pressures above 160/100 mmHg should be treated before diving, with medications that don’t impair exercise tolerance or thermoregulation.

Cholesterol alone isn’t a dive limiter, but elevated levels signal atherosclerotic risk. If you’re on statins, monitor for side effects like muscle soreness that could mimic decompression illness, and focus on overall cardiovascular endurance.

Diabetes and modern diving

Old blanket bans on insulin use have evolved into structured protocols. The UK Diving Medical Committee and DAN both now permit diving for stable diabetics under controlled conditions.

The essentials: consistent glucose control, pre-dive monitoring, carrying fast-acting carbohydrates, and ensuring your buddy understands your management plan. Hypoglycaemia underwater remains a red flag – abort, surface safely, and don’t re-enter that day.

Lungs, asthma, and immersion pulmonary oedema

Modern physician guidance, including from the UHMS, allows well-controlled asthmatics with normal lung function and negative exercise tests to dive. Those with exercise-, cold-, or emotion-triggered wheeze should not.

Awareness of immersion pulmonary oedema (IPO) is equally vital. It manifests as sudden breathlessness or cough during a swim or dive, often in cold water or under exertion. If it happens: abort, establish buoyancy, administer oxygen, and seek medical evaluation. Address contributing factors like tight suits, cold stress, and hypertension before returning to the water.

Cardiac history: when and how to come back

After a heart attack, stent, or valve surgery, clearance depends on recovery and performance, not just time. Divers should undergo a full evaluation including a cardiac exercise test to replicate dive-level exertion. Many divers safely return once they are symptom-free, on stable medication, and meet realistic workload benchmarks. Conservative dive profiles and warm, low-stress environments are wise early on.

The practical fitness blueprint for divers

1) Annual medical alignment
Complete your agency’s self-declaration and seek a dive-literate doctor if you answer “yes” to any condition. BSAC medical referees follow structured review intervals, which increase with age.

2) Train for the task
Three to five aerobic sessions per week (150–300 minutes of moderate or 75–150 minutes of vigorous activity) plus two strength days hit most diving goals. Swimming and finning drills build the exact endurance required underwater.

3) Build strength where it counts
Focus on legs, back, and core. Exercises like squats, step-ups, and carries directly translate to hauling gear and ladder climbs.

4) Manage weight and blood pressure
Even if obesity doesn’t directly cause decompression sickness, it correlates with the cardiac events dominating dive fatalities.

5) Acclimatise to cold
Cold water increases cardiac afterload and IPO risk. Ensure exposure protection is well-fitted and pre-warm before immersion.

6) Minimise breathing workload
Keep regulators serviced and your trim efficient. Streamlining gear reduces exertion and gas consumption.

The over-40 diver’s health checklist

• Blood pressure well-controlled on stable medication.
• No unexplained chest pain, breathlessness, or fainting episodes.
• Stable diabetes with clear self-management plan.
• Asthma under control with documented clearance.
• Awareness of IPO symptoms and contributing factors.
• A verified capacity test aligning with ~10–12 MET targets.

Smarter profiles for a longer dive life

Prioritise quality over difficulty, especially early in a trip. Stay warm, plan gas conservatively, and maintain close buddy contact – separation is a recurring theme in diving fatality reviews. Small improvements in conditioning and planning compound into decades of extra underwater freedom.

Bottom line

Diving longevity isn’t about youth or muscle tone, it’s about functional fitness, medical awareness, and making choices that respect physiology. Following guidance from DAN, UHMS, and BSAC ensures your health keeps pace with your passion. Train with purpose, dive within your limits, and your best underwater years are still to come.