Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
Aquatic Training in Rehabilitation and Preventive
Medicine
Prins, J.
Department of Kinesiology and Rehabilitation Science, University of Hawaii,
Honolulu, Hawaii. U.S.A.
IntroductIon
Aquatic physical rehabilitation is now recognized and utilized as a “procedure,”
rather than a modality. The increased focus can be attributed in
part to its evolution from the limited confines of “Hubbard Tanks,” to
the larger venues of swimming pools. The larger exercising areas serve
as a venue for performing a greater variety of exercises, including those
that require sustained propulsive movements.
The physical properties of water provide a unique environment for
improving strength, flexibility, and cardiovascular conditioning. Although
exercise in the water, including formal swimming strokes have
historically been used for the recovery from injury, there is now an increased
focus on incorporating specific aquatic exercise protocols for
treating persons with acute or chronic clinical conditions, including persons
with permanent physical disabilities (Becker & Cole 1994; Cole
et al. 2004; Genuario & Vegso 1990; LeFort 1994; Prins & Cutner
1999); Thein & Brody 1998).
oVerVIeW And PrecAutIons
As a rule, voluntary movements in the water are viewed as “learned
skills” requiring instruction and taking time to develop. Furthermore,
kinesthetic feedback provided by the water is subtle, and therefore, effective
movement patterns need to be practiced and closely monitored.
A person who has previous aquatic experience may be expected to begin
aquatic physical therapy with less apprehension than someone unfamiliar
with the water. However, past experience can be an impediment to recovery
because there remains the risk of “overuse” or in the case of recovery
from injury, the person may revert back to familiar swimming stroke patterns
that may exacerbate symptoms and prolong the recovery period.
The recommendation, therefore, is that when initiating aquatic exercise
following injury, participants remain under the supervision of a
trained clinician or aquatic specialist until such time as they are pain
free and able to continue independently with their routines, and when
warranted, transition to land-based physical therapy (Prins & Cutner
1999; Thein & Brody 1998).
the AdVAntAGes oF eXercIsInG In the WAter
Two important physical properties of water; buoyancy and viscosity, are
key elements in designing effective aquatic exercises.
The Force of Buoyancy and its Effect on Weight Bearing During Immersion:
The advantage derived from buoyancy is direct; when a person enters
the water there is an immediate reduction in the effects of gravity on the
body. The buoyant force of water decreases the effective weight of an individual
in proportion to the degree of immersion. The ability to control
joint compression forces by varying degrees of immersion is of particular
benefit in the treatment of persons who demonstrate intolerance to axial
loading, particularly in the spine, hips, and lower extremities. By monitoring
the depths at which functional movements such as walking and
stepping are performed, the effect of gravity can be re-introduced which
in turn promotes effective recovery through gradual strengthening (Cole
et al. 2004; Prins & Cutner 1999).
Viscosity of Water and Muscle Strengthening: The viscosity of the water
offers tangible resistance. Because of the “drag” forces created by the
water, the degree of effort is determined by the cross-sectional area of
the moving body or limb, coupled with the velocity of the movement.
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Water can be seen as providing a “variable accommodating” resistance.
The advantage of an accommodating resistance is that it matches
the applied force or effort. In clinical terms, because the resistance of
the water approximates the applied muscular forces, the probability of
exceeding tissue tolerances is reduced and consequently, the likelihood
of exacerbation of the injury is dramatically reduced. The term “variable”
refers to being able to change the speed or velocity of the movement.
Because most human motion is variable in nature, functional gains are
more likely to occur when exercising in this manner (LeFort 1994; Prinset
al. 2006; Rahmann et al. 2009).
Cardio-respiratory Fitness and Muscular Endurance in the Water: The loss
of cardio-respiratory fitness can be significant during recovery from injury.
Therefore, early resumption of exercise is now considered essential
to the successful return to pre-injury activity. Aquatic therapy allows
the injured person to begin exercising earlier. Aquatic running or jogging,
when supported by a floatation device, offers additional benefits,
most notably, the maintenance of rapid stride frequencies without the
impact of landing, and coordinated movements between the arms and
legs (Becker & Cole 1994; Prins et al. 2006).
Insufficient muscular endurance, rather than insufficient strength, is
now seen as the primary factor present in an individual’s inability to
maintain the margins of safety of the spine, particularly when performing
the “activities of daily living”. Recent research shows that the ability
to improve and maintain spinal stability following injury requires low
intensity, continuous muscle activation (Cole, et al. 2004; McGill 2001).
As noted above, aquatic exercise allows for sustained movements with
less risk of overuse.
Social, Emotional, and Psychological Benefits of Aquatic Physical Therapy:
Patient motivation and compliance with treatment are positive determinants
for the success of any rehabilitation program. Because of the
unique properties of water, aquatic physical therapy is an excellent rehabilitation
choice, ensuring a high degree of compliance (Becker, Cole
1994).
clInIcAl dIAGnoses And condItIons treAted
WIth AQuAtIc eXercIses.
Injuries to the Spine and Extremities: The therapeutic advantages of exercising
in the water for early restoration of joint mobility in the spine,
combined with progressive strengthening are well documented (Fappiano
& Gangaway 2008; Lund et al. 2008; Rahmann et al. 2009).
Exercises in water are used for strengthening the cervical and thoracic
regions and are coupled with strengthening of the scapula stabilizers
and glenohumeral musculature (Becker & Cole 1994; Cole et al. 2004;
Prins & Cutner 1999).
For treatment of cervical injuries, an added advantage of the water
is the ability to perform neck-strengthening exercises while floating in
the prone position. When a mask and snorkel are used for breathing in
the prone position, the buoyant force of the water can be relied on to
support the weight of the head. This relieves injured muscles and associated
soft tissue from the responsibility of counteracting anticipated
gravitational forces.
Although the treatment of lower back injuries can take various
forms, a common goal is to increase strength and mobility of the weakened
area. Being supported by the water while standing or walking
at varying depths, alters the axial loading on the spine. Gravitational
forces are also minimized when the patient assumes a prone or supine
floating position. Swimming and kicking in the prone and/or supine
body positions, utilizing the neutral spine concept and modifying stroke
mechanics for individual patients (Cole et al. 2004; Lund et al. 2008) .
When recovering from hip, knee and ankle injury, especially after
surgery, the force of buoyancy can be used to decrease the weight of the
body while promoting early ambulation. Because joint reaction forces
on the knee can reach several times body weight (Fappiano & Ganga-