Kinesiology/Biomechanics LAB - Final Exam

LAB 1 - Jump Testing

What are the different phases of a countermovement jump? What occurs during each phase?

3 main phases:

Eccentric Phase - lowers body

Transition Phase - prepare to jump

Concentric Phase - explosively extend their legs to propel themselves upward.

Which would you expect to produce a higher jump height: a CMJ or squat jump? Why?

CMJ, because the quick dip stretches the muscles and stores elastic energy, which helps you push off harder and jump higher.

Functional anatomy: for each jump CMJ, Squat Jump, Depth Jump

The CMJ, squat jump, and depth jump all rely on hip, knee, ankle, and spinal movements in the sagittal plane. The eccentric phase involves flexion at the hip and knee with ankle dorsiflexion. The concentric phase involves extension at the hip, knee and plantarflexion at the ankle. The prime movers are the gluteus maximus and hamstrings at the hip, quadriceps at the knee, gastrocnemius and soleus at the ankle, and erector spinae at the spine.

LAB 2 - Gait Analysis

Describe stride length, stride rate, and how these values relate to gait velocity.

Stride length - how far you travel with one stride.
Stride rate - how many strides you take per second.
Gait velocity - how fast you move.

Relationship:
Velocity = stride length × stride rate.

What are the key differences between walking and running?

Walking - no flight phase

Running - flight phase and higher forces

LAB 3 - Bench Press

Describe the relationship between negative and positive work during a full rep of the bench press

Negative work: (eccentric phase) lowering the bar to your chest - muscles lengthen

Positive work: (concentric phase) pushing the bar upwards - muscles contract

Describe the relationship between intensity and power, intensity and kinetic energy, and intensity and momentum.

Intensity and Power - Power is highest at moderate loads

Intensity and Kinetic Energy - Heavier load → bar moves slower → KE doesn’t increase much

Intensity and Momentum - Momentum increases with heavier loads because mass rises, and velocity drop isn’t enough to cancel it

Functional anatomy for all the joints involved (shoulder girdle, shoulder joint, elbow, radioulnar, wrist/hand

Shoulder girdle moves the scapula (up, down, in, out, rotate) using the traps, serratus anterior, rhomboids, and levator scapulae.

Shoulder joint is a ball-and-socket that moves the arm in all directions using the deltoids, pec major, lats, and rotator cuff.

Elbow is a hinge that flexes and extends using the biceps, brachialis, and triceps.

Radioulnar joints pronate and supinate the forearm using pronator teres, pronator quadratus, supinator, and the biceps.

Wrist and hand flex, extend, and deviate using the forearm flexor muscles, extensor muscles, and hand muscles.

LAB 4 - Angular Kinetics and Kinematics

When is linear acceleration present in angular motion?

Linear acceleration occurs when angular speed is changing, either speeding up or slowing down. No linear acceleration if rotation is at constant angular velocity.

When is angular acceleration positive, negative, or zero?

Positive - speeding up in the direction of rotation

Negative - slowing down (opposite to rotation)

Zero - moving at constant angular speed

Functional anatomy for shoulder extension vs flexion

Shoulder flexion and extension both occur at the glenohumeral joint, made of the humerus and scapula.

Flexion is lifting the arm forward in the sagittal plane, done by the anterior deltoid and pec major (clavicular) which start on the clavicle and insert on the humerus, innervated by the axillary and pectoral nerves.

Extension is moving the arm backward in the sagittal plane, done by the latissimus dorsi, teres major, and posterior deltoid, which start on the scapula or spine and insert on the humerus, innervated by the thoracodorsal, subscapular, and axillary nerves.

LAB 5 - Muscular Considerations

Which is stronger: a maximal eccentric contraction or a maximal concentric contraction?

Eccentric is stronger because muscles can resist more force while lengthening.

Where did elbow flexors/extensors produce the greatest torque?

Mid-range of motion (90° for flexors).

• Muscle length allows optimal cross-bridge overlap → more force.

• Leverage (moment arm) is greatest at that joint angle.

What types of forces act on the forearm during elbow flexion?

Axial (compression/tension) - along the length of bones

Non-axial (shear/bending) - from muscle pull off-center

Combined loads - bending + torsion + axial compression

LAB 6 - Neural Considerations

What does Electromyography measure in the isometric midthigh pull?

EMG measures muscle activation (electrical activity) during the pull.

Higher EMG = more motor units firing and/or higher firing rate.

How does muscle activation relate to force production in the isometric midthigh pull?

More activation → more motor units recruited → higher force.

Early activation (rapid rise in EMG) → faster rate of force development (RFD).