title: The effect of pre-dive exercise timing, intensity and mode on post-decompression venous gas emboli.
abstract: BACKGROUND
  The effect of pre-dive exercise on post-decompression venous gas emboli (VGE) remains contentious. The aim of our study was to investigate the effect of timing, intensity and mode of exercise before diving on post-decompression VGE production.
  
  
  METHODS
  Fifteen male volunteers performed three identical 100 min chamber dives to 18 metres' sea water. Two of the three dives were conducted with prior exercise at 24 or 2 h; a dive without prior exercise formed the control. Moderate-intensity impact exercise consisted of jogging on the spot for one minute followed by ten star jumps, repeated for a total of 40 min at 70% of maximum heart rate. Post-dive Doppler monitoring began within 2 min of surfacing and was carried out for at least 180 min. VGE were assessed using the Kisman-Masurel (KM) code and the Kisman Integrated Severity Score (KISS).
  
  
  RESULTS
  The median peak KM grade for each condition following the dives was not significantly different. Pre-dive exercise at 2 h resulted in a significant reduction in the mean KISS compared to the control (11.3 versus 17.2, P < 0.04, Wilcoxon sign-ranked test). Moderate-intensity jogging/star jump exercise used in this series of dives resulted in significantly lower mean KISS (11.3 versus 21.8, P < 0.04) and median KM grade over 180 min (P < 0.006, Mann Whitney U test) compared to high intensity cycling exercise used previously.
  
  
  CONCLUSIONS
  This study suggests that moderate-intensity impact exercise reduces VGE production when conducted 2 h prior to diving.
authors.affiliation: Principal Investigator, QinetiQ Haslar, Gosport, Hants, United Kingdom, PO12 2AG, Phone: +44-(0)2392-335152, Fax: +44-(0)2392-335192, E-mail: kmjurd@qinetiq.com.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Jurd
authors.forename: Julian C
authors.initials: JC
authors.lastname: Thacker
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Seddon
authors.forename: Mikael
authors.initials: M
authors.lastname: Gennser
authors.forename: Geoffrey Am
authors.initials: GA
authors.lastname: Loveman
mesh_terms: D003664:Decompression; D003665:Decompression Sickness; D004242:Diving; D004618:Embolism, Air; D006801:Humans; D014680:Veins