2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
56
Figure 2. The no of heart beats in 30 seconds after 30s recovery from a 3min step test
The CIVD test produced consistent results over the two longer legs. In both cases finger
temperature fell closer to water temperature at the end compared to start of the Legs (Figure
3). The average difference between finger temperature at the start and end of the first Leg
over the last 10 minutes of the CIVD test was 4.6°C, the corresponding figure for the second
leg was 10.7°C. No difference was seen in this test over the last Leg, or between the first and
last test undertaken in Bilbao. This suggests that the skipper was not cold injured by the
voyage, and the reduced finger temperature at the end of the first and second legs was
probably due to greater sympathetically-induced vasoconstriction as a result of the mild
dehydration.
DISCUSSION
The initial analysis of the data from the first skipper studied, suggests that the longer Legs of
the solo circumnavigation had a significant impact on body fat, muscle mass and hydration.
The negative fluid and energy balances experienced by the skipper are worthy of note and
support the findings of earlier studies. Despite this, and the associated sleep deprivation,
muscle strength and endurance was unaffected while aerobic fitness may have improved
slightly. This is likely to have been due to the mild aerobic exercise and recovery from
anaerobic activity required to skipper the yacht. Whilst the dehydration did not appear to
impair performance on the tests undertaken, dehydration does increase the likelihood of an
individual developing a cold injury; this is supported by the CIVD tests results. The negative
energy balance of the skipper was corrected by the stopovers, however a non-stop
circumnavigator would be unlikely to tolerate this rate of imbalance (it would result in about a
25% reduction in body mass!). Further work is required to establish the maximum negative
energy balance that can be tolerated over a given duration of voyage, and still enable adequate
and recoverable physical and mental performance.
566
No. of heart beats
40
42
44
46
48
50
52
54
Start End Leg 1 Stopover End Leg 2 Stopover End
Bilbao Fremantle End of Norfolk End of Bilbao