Biomechanic of Swimming

1. Biomechanics Biomechanics
of of
SwimmingSwimming

2. Swimming
•Stroke: physical movements through the
water
●
Measured in rate and length
•Start: dive position, hand grip on block,
breathing pattern in preparation, dive
depth
•Turn: use of inverted positions, pressure
off the wall, underwater preparatory time/
depth

4. How do we assess a swimmer?
•Stroke length
●
Stroke length increases on distance events
•Stroke frequency
•Velocity
●
Rate and velocity typically decline over the
course of a race
•Sprinting speed
●
Force and efficiency

5. Swimming Speed and
Efficiency
•Factors influencing swimming velocity
–Stroke length
–Stroke frequency
Swimming = Stroke x Stroke
Velocity Length Frequency
V = SL x SF

6. •Swimming efficiency
–Ratio of mechanical work performed to energy
expended to do work as determined by VO
2
•Total efficiency is divided into
–Mechanical (propulsion) efficiency
•Ratio of power used to overcome drag over power
expended in performing movements
–Metabolic efficiency
•Ratio of power used to perform movements to
power consumed by swimmer
Swimming Speed and Efficiency

9. Swimming Stroke
•Front crawl
•Backstroke
•Breaststroke
•Butterfly

10. Front Crawl

11. Front Crawl
•Hand performs insweep
for propulsion (catch
phase), this motion rotates
below the the body,
behind and up for recovery
•4-6 beat kick with slight
ankle flexion
•Body roll during pull-
through
•Breathe every, every 3
rd

or 5
th
stroke

12. Front Crawl
•“Freestyle”
•Consist of right and left armstroke and
varying number of kicks
–Armstroke
–Flutter kick
–Body position and breathing style
–Rhythms between arms and legs

13. Armstroke
•Phases of armstroke
–Propulsive phases
•Downsweep
•Catch
•Insweep
•Upsweep
–Recovery phases
•Release and recovery
•Entry and stretch

14. Entry and Stretch
•Hand enters water in streamlined manner
•Arm moves forward
•Easy to produce wave drag

15. Downsweep and Catch
•Downsweep
–Beginning of propulsive phases
–to position arm for propulsive sweep
–Sweep down in curvilinear path
•Catch
–Take place near the end of downsweep
–Palm is rotated outward

16. Insweep
•The first propulsive sweep
•Arm travels under body to midline
•Sculling movement
•Hand don’t travel at max velocity

17. Upsweep
•Final propulsive sweep
•Hand is rotated out quickly
•Hand accelerates to max velocity

18. Release and Recovery
•Hand leaves water
•To place arm in position for another
underwater stroke
•Goal of recovery
–To get arm over water with the least
disruption of lateral alignment
–To provide short period of reduced effort for
arm, shoulder and trunk muscles

20. Propulsive Movements by
Hands-Arms
•Two methods for moving hand-arm unit
–Paddling method ; using drag force

21. Propulsive Movements by
Hands-Arms
–Sculling method ; using primarily lift force

22. Propulsive Drag Force

23. Propulsive Lift Force

24. Flutter Kick
•Primary directions are up and down
–Upbeat
–Downbeat
•Propulsive phase of kick
–To counteract tendency of body to be pushed
up or to side by movements of arms

25. BreaststrokeBreaststroke

26. Breaststroke
•Broken into outsweep, insweep, recovery
•Outsweep initiates at midline, moving laterally 12-15
inches, rotates into an insweep towards the chest
•Kick: knees and hips flex as the feet are drawn toward the
body, feet turn outward to generate propulsion and surface
area; knees slightly wider than hips

27. Phases
•Divided into 4 phases
–Glide/Post-thrust
–Breathing
–Recovery
–Pre-thrust

29. Glide/Post-thrust
Arm Action Leg Action

30. Body Position
•Streamline in stroke and
in pulldowns
•Shoot the hands forward
so that when they kick
they are already going
into the streamline

31. Breathing

32. Recovery

33. Body Position
•For every inch the
head is lifted, the hips
sink two inches
•For every inch above
the surface the head
is lifted, it will take
additional time to get
to the streamline
position

34. Pre-thrust

35. Leg Action
•Types of kick
–Frog kick
•Legs are drawn, knees turn outward and separate
more than feet
•Knees rotate inward as soles thrust outward
backward
–Whip kick
•Knees drop and separate as heel
•Feet turn outward as leg whip out and back

37. Butterfly Stroke
•“s” insweep of the arms
with full lateral extension,
typically wrists relaxed in
unison movement
•Coordinated undulation of
the body
•Legs in a two beat unison
kick, knees extend slight
ankle flexion (down beat
stronger than second kick)
•Breathe either every, or
every other stroke

40. Dolphin Kick
•Flow travels along dorsal surface of foot
•Magnitude of propulsive force depends on
–Propulsive lift force
–Resistive drag
–Rate of kick
–Forward speed of body and legs
•Initiated from thoracic spine
•Eel-like movement of total body

41. Streamlining Technique
•First streamlining technique
–Enter with hands at shoulder width as the first
kick is executed
–Downbeat dolphin kick serves to set body and
hips high
–Propulsive force generated by arms

42. Streamlining Technique
•Second streamlining technique
–First-half of propulsive stroke cycle
–Arms are positioned to deliver max drag
–Stretch legs up during propulsive phase

43. Streamlining Technique
•Third streamlining technique
–Recover legs during the arm recovery
–Trunk is positioned closer to horizontal
–Conserving forward momentum
–Second dolphin kick serves to support hips

47. Vortex Theory of Propulsion
•Possibility of swirling masses of water
•Vortex formed beside tail portion

48. Sweeping Pattern
•There are 3 or 4 sequences of sweeping
movements

49. Sweeping Pattern
•Hands enter water at shoulder width with
palm slightly outward
–Angled hand entry allows smooth transfer of
momentum developed during arm recovery
•Then, hands sweep inward as moving
under the trunk
–Drag propulsion is generated on hand/arm
surface

50. Sweeping Pattern
•Final propulsive sweep moves hands out
of water and into recovery phase
•Hands movements are rounded
•Hand speed continues to accelerate

51. Backstroke
•Propulsion
generated by
adduction of the
arms and internal
rotation of the upper
body
•Body roll as a key
factor
•4 or 6 beat kick
•Flexion and
extension of knee &
ankle; gluteal
engagement

53. Body Position
•The ideal body
position is as close to
horizontal as possible
•Streamlining is similar
to freestyle
•A flutter kick assists
with trunk stability

54. Rolling Action of Trunk
•A smooth rolling action of trunk, approx.
40-45 degrees to either side, will assist in
rotating shoulders
•Serves to position hand/arm for propulsion
•Serves to lift shoulder out of water and
streamline trunk

55. Armstroke
•The pulling pattern is shaped like an ‘S’
•Slow stroke rate tend to add more dept
•Faster stroke rate has a very linear pulling

56. Armstroke
•Propulsive phase
–Catch position
–Hand enters water with
palm is facing outward
•To minimize resistance
•To maintain momentum
during arm recovery

57. Armstroke
•Propulsive phase
●
Lift force act as hands moves downward
●
Drag force takes effect
●
At mid-stroke may be combined with a slight
insweep due to increasing elbow bend
●
Hand pushes toward feet

58. Armstroke
•Recovery phase
–Arm swings upward in an arc above shoulder
–Assisted by rotation of trunk around long axis
of body