Download ch 10 File - CSUN Moodle

Chapter 10
Analysis of Exercise and Sport Movements
Common Muscle Groups
More Upper arms
More trunk
More Legs and Abs
Wide Lat Pull-down
Seated Barbell press
Seated pulley row
Squat
Variations in Technique
• Create different muscle recruitment
– Timing
– duration
– Percentage max
– Muscle Isolation
Biceps etc
• hammer curls and EZ-bar curls maximize the contribution from
the brachioradialis ( moves to midposition (between supination
and pronation).
• Supinated curls and EZ-bar curls target the biceps brachii
because this muscle is also the strongest supinator of the
forearm.
• The brachialis is the prime mover for reverse curls because its
insertion on the ulna means its line of pull, and therefore its
length, is unaffected by forearm pronation or supination.
– Although the biceps brachii is recruited in a reverse curl, it is at an
anatomical disadvantage to maximize its force contribution. This explains
why you can’t pronate (reverse) curl as much weight as you can during a
hammer, EZ-bar, or supinated curl.
Example of Muscle Isolation
• Concentration curls and preacher curls help isolate the
elbow flexors because the upper arm is supported,
thereby reducing the contribution from the shoulder
flexors.
• Next time you perform a standing curl, be conscious of
the contraction produced by the anterior deltoid and the
clavicular portion of the pectoralis major. Why are these
muscles active? As soon as you start to flex the elbow,
the weight wants to drive the shoulder joint into
hyperextension to balance the load against your body. In
other words, the shoulder flexors contract to counteract
the extensor torque produced by the weight.
difference between a flat and an
incline bench press
• For a flat bench press, the primary concentric shoulder
joint motion is horizontal adduction, but with an incline
bench press, the concentric motion becomes a
combination of horizontal adduction and flexion.
Because the sternal portion of the pectoralis major is a
shoulder joint extensor (once the arm is flexed in front of
the trunk), it will start to drop out (i.e., become less
active) as the incline increases. Using the incline bench,
therefore, targets the clavicular portion of the pectoralis
major because it functions as both a horizontal adductor
and flexor of the shoulder. Notice that as the incline
steepens to 90°, you switch from performing a bench
press to performing a shoulder press. The steeper the
incline, therefore, the more you lose the sternal portion
of the pectoralis major, and the less weight you can lift.
difference between a narrow- and
wide-stance squat
• In a narrow-stance squat, the principal
concentric hip joint movement is
extension. In the wide-stance squat, the
concentric hip motion is a combination of
extension and adduction. Using this
technique, therefore, calls on the hip
adductors to work with the hip extensors to
control the weight.
close-grip and wide-grip lat pulldown
• both the close-grip and wide-grip lat pulldown recruit the latissimus dorsi, teres
major, and sternal portion of the pectoralis
major. In the close-grip lat pull-down,
these three muscles are recruited as
shoulder joint extensors. In the wide-grip
lat pull-down, however, they function as
shoulder joint adductors.
Cycling
• Air Resistance
– Form drag (also referred to as shape, profile, or pressure
drag) is produced by the cyclist’s body, and the bike,
parting the air. The amount of form drag depends on the
size, shape, and speed of the cyclist and the bike, as well
as the orientation of the cyclist’s body with respect to
airflow.
– Surface drag (also referred to as frictional resistance,
skin resistance, skin-friction drag, or skin drag) is
produced as air passes over the surface of the cyclist and
the bike. For example, friction created between the air and
the cyclist’s skin and clothing slows the air and, therefore,
resists forward motion.
Pedaling cycle
• The pedaling cycle is normally divided into two phases: a
power phase that drives the bike forward and a recovery
phase. The power phase starts when the crank arm (the
portion of the crank from the crank axis to the pedal) is at
top dead center (TDC), or 0°, and ends when the crank arm
reaches bottom dead center (BDC), or 180°.
Normal Force (Fn) and Tangential Force (Ft)
vs Parallel Force and effective Force
Cadence and Seat Height
• 70-100 rpm
– 160 rpm sprint
– Long distances
• 110 short bursts
• Aerodynamics
• Metabolic
– 150º (25º-30º)
Swimming
• Form drag
• Surface drag
• Wave drag is caused by the swimmer’s body
moving near or along the surface of the water.
– A portion of the water displaced by the swimmer
moves up from a zone of high pressure to a zone of
low pressure, creating a wave.
– Because the swimmer’s kinetic energy provides the
energy needed to form the waves, the waves present
an opposing force to the swimmer. As the speed of
the swimmer increases, the opposing force of the
waves also increases.
Stroke
Stroke Mechanics
• To maximize forward propulsion during the power
phase of all the strokes, swimmers are instructed
not to use a straight pull (referred to as paddling)
with the hand oriented 90° to the surface of the
water.
• Instead, the angle of the hand (angle of attack, or
pitch) should vary throughout the power phase, and
the hands should follow a curvilinear path through
the water (figure 10.9a). This stroke technique is
known as sculling.
• In addition, during freestyle and backstroke, the
whole body (i.e., shoulders, trunk, hips, and legs)
rotates as one unit through a range of 70 to 90o, or
35 to 45o to each side.
Propulsive Forces Produced by the
Arms and Hands
• The force acting on the hand as it passes
through the water is normally divided into
two components:
– a lift force that acts perpendicular to the
hand’s line of pull and a
– drag force that acts in the opposite (i.e.,
parallel) direction to the motion of the hand.
– The magnitude of the lift and drag forces is
determined by the pitch (angle of attack) of
the hand (figure 10.9).
Propulsive Forces
Swimming Velocity and Momentum
• Swimming velocity is largely determined
by the product of stroke length (SL) and
stroke rate (SR). Depending on the
duration and speed of the swimming
event, a correct combination of SL and SR
must be used to maximize performance.
• streamlined body position
Drag and Lift forces of lower limb
Dance