The general rule is to avoid heavy excercise before, during and immediately after diving. How long before I'll leave to the experts, good question.
Indeed, Tortuga68, that was the "general rule" and a while back I published a piece consistent with these recommendations -->
Doc Vikingo's Exercise & DCS
However, as bleep has stated, these guidelines gradually are being reconsidered (and not without controversy) , especially as regards exercise prior to diving. At present we still need to determine with more precision such variables as the exact nature of the exercise and time frames both pre- and post-dive, as well the effects of such excerise on plain old Joe and Jane Diver, not just on healthy young male military divers.
The following research articles are examples of findings that are prompting reevaluation:
1. J Physiol. 2004 Mar 16;555(Pt 3):637-42. Epub 2004 Jan 30.
Aerobic exercise before diving reduces venous gas bubble formation in humans.
Dujic Z, Duplancic D, Marinovic-Terzic I, Bakovic D, Ivancev V, Valic Z, Eterovic D, Petri NM, Wisløff U, Brubakk AO.
Department of Physiology and Biophysics, University of Split School of Medicine, Split, Croatia.
zdujic@bsb.mefst.hr
Comment in: J Physiol. 2004 Mar 16;555(Pt 3):588.
Abstract
We have previously shown in a rat model that a single bout of high-intensity aerobic exercise 20 h before a simulated dive reduces bubble formation and after the dive protects from lethal decompression sickness. The present study investigated the importance of these findings in man. Twelve healthy male divers were compressed in a hyperbaric chamber to 280 kPa at a rate of 100 kPa min(-1) breathing air and remaining at pressure for 80 min. The ascent rate was 9 m min(-1) with a 7 min stop at 130 kPa. Each diver underwent two randomly assigned simulated dives, with or without preceding exercise. A single interval exercise performed 24h before the dive consisted of treadmill running at 90% of maximum heart rate for 3 min, followed by exercise at 50% of maximum heart rate for 2 min; this was repeated eight times for a total exercise period of 40 min. Venous gas bubbles were monitored with an ultrasonic scanner every 20 min for 80 min after reaching surface pressure. The study demonstrated that a single bout of strenuous exercise 24h before a dive to 18 m of seawater significantly reduced the average number of bubbles in the pulmonary artery from 0.98 to 0.22 bubbles cm(-2)(P= 0.006) compared to dives without preceding exercise. The maximum bubble grade was decreased from 3 to 1.5 (P= 0.002) by pre-dive exercise, thereby increasing safety. This is the first report to indicate that pre-dive exercise may form the basis for a new way of preventing serious decompression sickness.
2. Aviat Space Environ Med. 2006 Jun;77(6):592-6.
Venous bubble count declines during strenuous exercise after an open sea dive to 30 m.
Dujić Z, Obad A, Palada I, Ivancev V, Valic Z.
Department of Physiology, University of Split School of Medicine, Croatia.
zdujic@bsb.mefst.hr
Abstract
INTRODUCTION: The effect of post-dive exercise on bubble formation remains controversial, although the current practice of divers and aviators is to avoid strenuous exercise after diving. Previously, we have shown that exercising 24 h before a dive, or during a decompression stop, significantly reduces bubble formation in man. The objective of this study was to determine whether a short period of strenuous post-dive exercise promotes venous bubble formation. METHODS: Seven male military divers performed an open-sea field dive to a maximum depth of 30 m for 30 min. At maximum depth, subjects performed mild underwater fin swimming, followed by standard decompression. Diving was followed by a post-dive exercise session consisting of short, strenuous incremental upright cycle ergometry, up to 85% of maximal oxygen uptake, for about 10 min. Subjects were monitored for venous gas bubbles in the right heart with an echo-imaging system starting 20 min post-dive while in the supine position, during cycle ergometry in the seated upright position, and immediately after exercise in a supine position. RESULTS: The average number of bubbles was 1.5 +/- 1.4 bubbles x cm(-2) 20 min after diving. Changes in posture from supine to seated upright resulted in significant reduction of bubbles to 0.6 +/- 1.3 bubbles x cm(-2) (p = 0.043), with further reduction to 0.2 +/- 0.3 bubbles x cm(-2) at the end of exercise (p = 0.02). No cases of DCS or intra-pulmonary shunt were observed during or following post-dive exercise. DISCUSSION: These results suggest that post-dive strenuous exercise after a single field dive reduces post-dive gas bubble formation in well-trained military divers. Additional findings are needed for normal sports divers.
Regards,
DocVikingo
