Biomechanics:

Study of the mechanics of motions

       Exercise
       Specific Skills (pushing, pulling, throwing, striking, kicking)
       Locomotion

Locomotion (movement of the body from one place to another)

       Types:
             On Solid Surface
             In an aquatic environment
             While suspended
             Free of support

Solid Surface Locomotion

       On foot (walking, running, climbing, etc.)
       On hands (walking)
       On hands and feet (crawling)
       On wheels (cycling), blades (skating), or runners (skiing)
       Rotary motions (cartwheels, tumbling)

Walking:

       Has been studied extensively (through muscle palpitation and EMG)
             Knowledge is so exact that laboratory stimulation of muscles has produced
             walking in paraplegic individuals

       Is a reflex action (no thought is necessary)
             - similar to chewing (gum)

       Is a translatory motion of the body from rotary motions of segments

       Phases: (swing & support)

             Swing (toe-off to heel-strike)
             Support (heel-strike to toe-off)
                   contains:    heel-strike, flatfoot, midstance, heel-off, toe-off
                   toe-off occurs during heel-strike to flatfoot phases

       Each leg has Swing and Support Phase

             Left HS to Right HS = Step
             Left HS to Left HS = Stride
       Components:

       Lower Body

             Pelvic Rotation, Pelvic Tilt, Knee Flexion, Hip Flexion, Knee/Ankle Interaction,
             Lateral Pelvic Displacement

       Upper Body

             Rotation of Trunk OPPOSITE to that of the Hips
             Swing of Arms OPPOSITE to that of the Legs

       Walking Speed:

             Is a function of Step Rate (SR) and Step Length (SL)
             SR can be increased by more steps / minute
                   - faster rate of cyclic neural recruitment
             SL can be increased by taking a longer step
                   - extend hips and knees maximally, plantar flex ankle

             Type of walking called race-walking
                   Contractions not excessively strong but repeated
                   Relies upon muscles that are resistant to fatigue

Running:

       Two types:
             For Speed (Sprinting, jogging)

             Within a sport (football, baseball)
                   - CG Balance can be as important as Speed

       Phases:
             Swing and Support

       Major Difference 1:
             Support phase contains the Time of Support (TS)
             Swing phase contains a Time of Non-Support (TNS) and a Time of Support

                   In walking, TO occurs during HS to Flatfoot phases
                   HS occurs after opposite foot TO in Running





       Major Difference 2:
             Position of CG with respect to heel-strike
             In walking, CG is far behind
                   - provides a braking effect (eccentric contractions of leg muscles)
             In jogging, CG is closer
                   - provides less braking effect
             In sprinting, CG is BELOW the foot at heel-strike
                   - eliminates any braking effect
                   - support phase now becomes "propulsion phase" exclusively

       Running Speed:

             Is also a function of SL and SR

             Increasing SL

               Distance runners:
                   Cavanaugh Study:
                          Put individuals on treadmill
                          Measured VO2 at certain speeds
                          Altered SL at these speeds
                          Significant differences found between VO2

                          Conclusions:
                          - There exists an optimal SL for each person depending upon the
                          speed at which a person is jogging
                          - However, joggers tend to gravitate to optimal SL, so don't alter
                          SL in joggers
               Sprinters:
                          - Are able to change SL with better results
                          - Research has attempted to determine optimal SL
                          - Fastest runners have similar Step Length / Height Ratios
                                Optimal SL/Ht Ratio is between 1.20 and 1.25
                                Excessive SL (overstriding) is not desirable

                          Increasing Step Length
                                Need "Speed-Strength" (strength at fast speeds)
                                Use:
                                       Resistance Training
                                             isotonic or isokinetic exercises
                                       Resistive Running
                                             pulling a sled
                                             using a running harness or parachute
                                             running uphill / upstairs
                                Once SL is at optimal length, increase Step Rate

                          Increasing Step Rate
                                Form Running Drills (A's and B's)
                                Towing (elastic harnesses)                         
                                Downhill running

                          Increasing Resistance to Fatigue
                                Need "Speed-Endurance"
                                Use:
                                       Interval Training