Stroke (Back crawl)

Swimming and Lifesaving Module
RESOURCE of ROYAL NAVY . THE ROYAL MARINES
STROKES
BACK CRAWL

At the beginning of the last century two forms of backstroke were being
performed. Both had leg actions similar in shape and pathway to that of
a wide inverted breaststroke but the arm actions differed. In the
elementary backstroke the arms were moved, simultaneously, from
shoulder level to the sides of the body, followed by an underwater
recovery. The continuing quest for speed brought about an alternating
arm action and, later, an alternating upward and downward leg kick
leading to the development of the back crawl stroke. The modern
version of the stroke has the arm action balanced by the leg kick,
accompanied by a noticeable body roll and reaction at the hips and feet.
The degree of reaction depends upon the performer’s physical
characteristics, associated with the application of basic techniques।

Body Position
The body is as horizontal as possible whilst maintaining an effective leg
action completely under water, but near the surface. The back of the
head is in the water with the hips high. The knees remain below the
surface and the toes just dimple the surface on the up kick .
The position of the head is important because a raised head makes a
hips-up position difficult, leading to a type of sitting position in the
water. A further requirement is that the body is stretched with legs and
feet extended and this depends on flexibility and mobility. Swimmers
with stiff ankles find the body position and the leg kick difficult to
achieve, while others with good flexibility in legs and ankles will adopt a
good position naturally. Competent swimmers use a shallow dish shape
which places the shoulder girdle and hips in an advantageous position
for the effective use of arms and legs।

Leg Action
Efficient back crawl swimming depends on an effective leg kick. It is
often described as an alternating up and down kick, suggesting an
action in a vertical plane. This might well happen when the swimmer is
involved in practices with legs only; however, when the arm action is
used, the kick is part sideways, part vertical and then partly to the other
side.
Before each kick up to the surface the knee bends, due to pressure of
the water against the front of the leg and ankle. It is accompanied by
some hip extension and movement of the leg backward, relative to the
spine (Figure 2). With the leg at its lowest position the up kick is
initiated by the powerful muscles of the hip. Then action passes to the
muscles which straighten the knee, accelerating the movement of the
pointed foot to the surface . At this time, intoeing often takes
place as a consequence of the natural structure of a flexible ankle joint.
Full extension of the knee occurs and the action ends in a whip-like
movement of the foot. The toes touch the surface if the pace is easy but
there is a lot of broken water in hard-paced swimming . The leg remains
straight for most of the downward movement with the sole of the foot
pressing on the water.
Whether propulsion is obtained depends on foot size, ankle mobility
and strength of legs. As one leg finishes its upward action the other leg
is at its lowest position with the foot some 30-60 cms (12-24 ins)
below the surface. The feet pass close to each other as the legs move
upward and downward।

Arm Action
In back crawl it is convenient to think of two possible extremes of
action:

a) bent arm action or S pull
b) straight arm एक्शन

The bent arm action technique is the more effective because it uses a
shorter lever permitting a faster action and it has a more effective
propulsive force, being closer to the line of progression. The straight
arm technique is not truly straight because the hand follows a semicircular
pathway, centred on the shoulder, and it is at its deepest
opposite the shoulder . It will be recalled that a long lever
moves more slowly than a short one. It will be recalled, also, that every
action produces an equal and opposite reaction and therefore only in
the middle part of the straight arm action will there be a fully effective
reaction. The first and last thirds of the semicircular action will produce
reactions to one side or the other. Observation reveals the straight arm
action to be deep, relative to the line across the shoulders. Such action
is weak considering the effective use of the strong muscles of
shoulders, chest and back . This is because the straight arm
technique is accompanied by a flatter body position with less roll. For
three reasons, therefore, the straight arm technique is less effective
than the bent arm one:
a) A long lever moves more slowly giving a slower stroking rate
b) Mechanically it produces less propulsion
c) Anatomically, it tends to place the muscles of the shoulder joint in a
weak position for effective action. If there is elbow bend, the elbow
tends to lead the hand।

Entry
The entry of the hand is similar for both techniques. It is preferable if
the little finger enters in advance of the hand and this requires some
rotation of the wrist. If the shoulders are not flexible, the back of the
hand enters first and when this happens the hand has to turn as it sinks
into the water. Generally, the entry is in line with or very slightly wide of
the shoulders but skilled performers tend to move nearer the central
line

Propulsion
a) Bent Arm Action
Catch. The hand turns and shapes early and in skilled performances
there is a distinct press down before purchase is gained at
approximately 15 cms (6 ins)
Pull. As the arm pulls, the elbow begins to bend, and as the movement
continues the arm rotates so that the hand catches up with the elbow.
The degree of bend, approximately 90°, can vary between individuals
and sometimes between right and left arms. The head remains in line
with the body, whilst the shoulder on the pulling side drops to obtain
the most advantageous position for the strong pull-push action already
mentioned
Push. Once the shoulder, elbow and hand are level, they are well
positioned for a powerful push. The hand continues to face towards the
feet until the arm is fully extended. For many swimmers, especially
learners, lack of strength may result in the push being weak in all or in
part. If the push is complete, it finishes with a fully extended arm b
elow the hips, the palm of the hand facing the bottom of the pool
A side view through the whole action shows the hand tracing a pathway
rather like a letter ‘S’ on its side (Figure 10).
b) Straight Arm Action
In this action the hand follows a semicircular pathway. After the catch
much of the pull is outward as the arm increases in depth, until it
reaches shoulder level; it is here that propulsion is most effective. As
there is very little bending at the elbow, the remainder of the action, the
push phase, tends to be inward towards the hip where it finishes. At no
time should the hand be lower than body depth।

Recovery
In this phase of the stroke the straight arm is lifted from the water
vertically, and returned directly to the entry position
There will be variations of the hand position in recovery and in the
manner of arm rotation required to allow the little finger to lead for
entry. However, the whole action should allow a smooth and flowing
transition between propulsion and re-entry. The rolling of the body aids
recovery by raising the upper shoulder clear of the water, thereby
reducing resistance.
The re-entry of one arm coincides with the full extension of the other at
the end of its propulsive phase।

Breathing
As the face is out of the water throughout the stroke, breathing should
present no problems. However, since it is important to breathe at
regular intervals, the method most commonly recommended is to
breathe in as one arm enters the water and to breathe out as the other
one enters।

Co-ordination
The co-ordination of arm and leg action develops with practice.
Normally, six beats of the legs occur during one complete arm cycle.
The opposite leg kicks downward at the beginning of each arm pull.
This helps to balance the body as in walking and running, when one
arm swings forward as the opposite foot steps forward, and vice versa.