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GRIP STRENGTH
Grip strength is a simple measure of strength. The
dominant hand will often score 10 percent higher
than the nondominant hand. As with many of the
tests we use, comparison of an individual’s pre- and
posttraining period performance can be useful.
PULMONARY FUNCTION
Proper lung function is essential to good health. The
inability to empty the lungs rapidly or inflate them
normally may indicate the presence of obstructive
or resistive pulmonary disease. Normal values vary
substantially with age, sex and height.
• Forced vital capacity (FVC) is the maximum amount of
air that can be forcibly moved out of the lungs during a
single effort. FVC is usually 75-80 percent of total lung
capacity. The air that cannot
be exhaled from the lungs is
the residual volume (RV).
• Forced expiratory volume
in the first second (FEV
1
)
represents the volume
forcibly exhaled in the first second of the four- to five-
second FVC maneuver. FEV
1
is normally more than
80 percent of FVC. This is usually presented as the
ratio of FEV
1
to FVC (FEV
1
/FVC).
• Forced expiratory flow 25-75 percent (FEF
25-75
)
represents the average flow rate during the FEV
effort. This can indicate the health of the medium-
and small-sized airways.
• Maximal voluntary ventilation (MVV) represents
the maximum amount of air that a person can inhale
and exhale in 15 seconds. MVV reflects the strength
and endurance of the respiratory muscles.
URINE CONCENTRATION
Urine concentration is not a measure of hydration, but it
does provide some insight when based on a meaningful
sample, preferably a complete 24-hour collection or,
alternatively, the first sample following a full night of rest.
(Note: Other voids are less useful because they are strongly
affected by immediate events.) Generally speaking, a
meaningful sample with low concentration indicates that
ample water is available in the body to preserve appropriate
fluid volumes. A more concentrated sample does not
confirm dehydration, but it indicates that minimal fluid is
being excreted. Fluid conservation could be sufficient to
preserve body water volume, but a pattern of concentrated
urine may indicate insufficient fluid intake.
CONCLUSIONS
The physical demands on a skilled diver can be modest,
but the possibility of intense emergency demands make
it important to maintain ample physical fitness reserves.
This requires honest evaluation
and commitment to preserving
healthy capacities. Incorporating
physical activity into a normal
lifestyle is a powerful way of
preserving capabilities.
AD
Table 6. Grip strength scores by gender
Classification Males (kg)
Females (kg)
Excellent
>64
>38
Very Good
56-64
34-38
Above Average 52-55
30-33
Average
48-51
26-29
Below Average 44-47
22-25
Poor
40-43
20-21
Very Poor
<40
<20
REFERENCES
1. Mitchell SJ, Bennett MH. Clearance to dive and fitness for work. In: Neuman TS, Thom SR, eds. Physiology and Medicine of Hyperbaric Oxygen
Therapy. Saunders, 2008: 65-94.
2. Ma AC, Pollock NW. Physical fitness of scientific divers: standards and shortcomings. In: Pollock NW, Godfrey JM, eds. Diving for Science
2007. Proceedings of the American Academy of Underwater Sciences 26th Symposium. Dauphin Isl, Ala.: AAUS, 2007: 33-43.
3. Buzzacott P, Pollock NW, Rosenberg M. Exercise intensity inferred from air consumption during recreational scuba diving. Diving Hyperb Med.
2014 June; 44(2): 74-8.
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MEET THE EXPERT
Neal W. Pollock, Ph.D., is a research director at DAN
and a research associate at the Center for Hyperbaric
Medicine and Environmental Physiology, Duke
University Medical Center, in Durham, N.C.
NEAL POLLOCK
JENNA WILEY