Q2-Spring-2016_Alert-Diver

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TRANSLATING FUNCTIONAL FITNESS
TEST RESULTS
Aerobic capacity (VO2 max) is defined as the maximum
amount of oxygen that can be consumed per unit of
time. This is classically determined with a continuous,
progressive exercise test to exhaustion. While too involved
for general use, VO2 max is a standard for referencing
overall fitness. The complicated units of milliliters of
oxygen consumed per kilogram body mass per minute
(mL/[kg·min -1]) can be simplified by converting VO2 max
values into metabolic equivalents (METs). METmax
is determined by indexing VO2 maxto resting oxygen
consumption (assumed to be 3.5 mL·kg-1·min-1, or 1 MET).
The higher the MET score, the higher the aerobic fitness.
An example of the conversion follows:
MET capacity (METmax) = VO2 max (in mL·kg-1·min-1) ÷ 3.5
e.g., 49 mL·kg-1·min-1 (VO2 max) ÷ 3.5 = 14 METs
A diver with good buoyancy control should work little
during a typical dive. A skilled diver swimming at
no more than 0.5 knot could be working at around 3
METs. A diver maintaining a pace of 1.2 knots could
be working in the 10-12 MET range. We inferred
workrate from open-circuit gas consumption during
959 recreational dives and conservatively estimated a
mean workrate of 5 METs.3
GETTING FIT FOR DIVING
The key to being physically fit to dive is to find a way to
stay active. The goal is to build or maintain reserves to
delay the point at which activity patterns have to decline.
Optimally, divers will be significantly physically active
daily and bolster this with 30-60 minutes of training-
quality activity three to four times per week. A mix of
activities is generally best to reduce the risk of injury and
boredom. (For suggested exercises, read our Dive Fitness
articles in each issue or online at )
Physical training should target three key elements:
strength, aerobic capacity and flexibility. Low-impact
activities reduce the risk of injury, and activities that
involve water provide the added benefit of improving
comfort in the diving medium.
FIELD MEASURES OF PHYSICAL FITNESS
We conduct field evaluations of diver physical fitness as
part of many of our research studies. We record a variety
of measures to provide a snapshot for participants, often
motivating them to improve their numbers.
BODY MASS INDEX (BMI)
Body mass index (BMI) is not a measure of body
composition; it is simply a ratio of weight to height (weight
in kilograms divided by squared height in meters). Despite
this, BMI is used to predict body composition since it is
more common for an increase to reflect an accumulation
of fat than lean tissue. While convenient, BMI can provide
a poor estimate on an individual basis, requiring common
sense for interpretation. With this caution in mind, those
with BMI values outside the desirable range should have
their body composition evaluated further. If a high BMI is
the result of excess fat, lifestyle changes that incorporate
additional exercise and dietary changes are recommended.
Table 2. BMI measurement classifications
WAIST-TO-HIP RATIO (WHR)
A high waist-to-hip ratio (WHR) — i.e., having high
girth in the midsection — may indicate an increased
risk of developing heart disease. WHR standards are
Classification BMI (kg·m-2)
Underweight <18.5
Healthy 18.5 - <25.0
Overweight 25.0 - <30.0
Obesity 30.0 - 40.0
Morbid Obesity >40.0
NEAL POLLOCK