33C H A P T E R

The Biomechanics of Resistance ExerciseThe Biomechanics of Resistance Exercise

Everett Harman

Chapter Outline

The musculoskeletal system

Human strength and power

Sources of resistance to muscle contraction

Joint biomechanics: concerns in lifting

Movement analysis and exercise prescription

Muscle Pulling Force Manifested As a Pushing ForceMuscle Pulling Force Manifested As a Pushing Force

Muscle Pulling Force Manifested As a Pulling ForceMuscle Pulling Force Manifested As a Pulling Force

Front View of Adult Male Human Skeleton

Front View of Adult Male Human Skeleton

Rear View of Adult Male Human Skeleton

Rear View of Adult Male Human Skeleton

The Vertebral ColumnThe Vertebral Column

Front View of Adult Male Human Skeletal Musculature

Front View of Adult Male Human Skeletal Musculature

Rear View of Adult Male Human Skeletal Musculature

Rear View of Adult Male Human Skeletal Musculature

A LeverA Lever

A First-Class Lever (The Forearm)A First-Class Lever (The Forearm)

A Second-Class Lever (The Foot)A Second-Class Lever (The Foot)

A Third-Class Lever (The Forearm)A Third-Class Lever (The Forearm)

Changes in Mechanical Advantage: Knee Extension and Flexion

Changes in Mechanical Advantage: Knee Extension and Flexion

Changes in Mechanical Advantage: Elbow FlexionChanges in Mechanical Advantage: Elbow Flexion

Changes in Mechanical Advantage: During Weightlifting

Changes in Mechanical Advantage: During Weightlifting

Most of the skeletal muscles operate at a

considerable mechanical disadvantage. Thus,

during sports and other physical activities,

forces in the muscles and tendons are much

higher than those exerted by the hands or feet

on external objects or the ground.

Variations in Tendon Insertion Variations in Tendon Insertion

Anatomical Planes of the Human BodyAnatomical Planes of the Human Body

Muscle Fiber Arrangements Muscle Fiber Arrangements

Interaction Between Actin and Myosin Filaments Interaction Between Actin and Myosin Filaments

Resistive Torque: Free WeightResistive Torque: Free Weight

Resistive Torque: Weight StackResistive Torque: Weight Stack

When a weight is held in a static position or

when it is moved at a constant velocity, it exerts

constant resistance, only in the downward

direction. However, upward or lateral

acceleration of the weight requires additional

force.

Supporting the Vertebral Column During Lifting: The Fluid Ball

Supporting the Vertebral Column During Lifting: The Fluid Ball

Resistance training is quite safe compared

with other sports and fitness activities.

Prudence can keep injuries to a minimum. Basic

safety principles include good lifting form,

appropriate resistance, accommodation to

injuries, balance, and variety.

Specificity is a major consideration when

designing an exercise program to improve

performance in a particular sport activity. The

sport movement must be analyzed qualitatively

or quantitatively to determine the specific joint

movements that contribute to the whole-body

movement. Exercises that use similar joint

movements are then emphasized in the

resistance training program.