DAN recommended 1999 that you can dive your dives in any order you prefer basing this on the fact that there were no research available to prove the opposite and it seems that the incidence of DCI had not increased when divers had ignored the classic approach. This has since been followed by lots of diver but PADI has decided to keep their traditional approach – a very wise decision I think.

In 2005 an article was published about reverse profiling which really puts things in a different perspective.

Multi-level dives

- Two groups of 11 guinea pigs each got to do each forward and reverse multi level dive profiles
- In the group which did the forward profile (normal approach) no DCI was detected
- 55% of the animals in the reverse group developed serious DCI and died

This is quite clear evidence that there is a significant difference in forward and reverse diving profiles. One should keep in mind though that humans are quite different to guinea pigs and that these profiles must be very extreme. Doing the same tests for humans would probably give quite different results but the trend would most likely be the same.

Repetitive dives

Repetitive dives are a little bit more realistic – I don’t actually think that many divers would do reverse multi level dives as suggested above.

- Two groups were then used to test repetitive diving
- None of the guinea pigs in the forward profile group were injured vs 33% in the reverse diving profile group

Conclusion

It is clear to me that we don’t fully understand exactly what is going on during decompression. Although many divers have done reverse profiles without getting bent does not mean that they are safe – the investigation above clearly indicates the opposite. In addition to this - almost all research on tables etc is done based on forward profiling. With all this in mind I would strongly recommend anyone to follow the traditional approach and avoid reverse profiles.

You can read the full article at Rubicon Foundation.

• Narcotic properties of N2, CO2 and O2 – Hesser et al
• Reverse profiling – Innes et al
• Deep stop research – Marroni et al

There is of course much more. I will discuss these articles in a later post. The Reverse Profiling article is really interesting reading and makes interesting food for thought.