Transcript Moment of force - Academy of Music in Krakow

BIOMECHANICAL
MEASURMENTS
OF PERCUSSIONISTS
Biomechanics …
 … combines the principles of mechanics with the
fields of biology and physiology:
 - Kinematics (used to describe motion)
 - Kinetics (considers forces in motion description)
Playing the percussion is a very physical art!
 Musicians are a group of people who perform very specified
movements over long periods of time, and can suffer from
strain-related injuries (Kaladjev, 2000)…
 … thus they require a consciousness of ergonomic issues.
Optimal movement strategy
Economical
minimise efford
avoid fatigue
Why to study players’ movements?
 To increase the knowledge about effciency and ergonomics in
skilled movements used for artistic purposes.
 To describe playing techniques and their effect on the
production of sound.
 To explore visual communication through movements in music
performance.
MEASUREMENTS - Overview
DYNAMICS
 DYNAMOMETER
 ELECTROMYOGRAPHY (EMG)
 FORCE PLATFORM
 KINEMATICS
 VICON (3D analysis)
 reaction time measurement
MEASURMENTS !!!
 MUSCULAR STRENGTHThe ability of the muscles to exert force.
 RATE OF MUSCULAR FORCE PRODUCTION
 MUSCULAR ENDURANCEThe ability to use the voluntary muscles many times
without getting tired.
 PROPRIOPCEPTION
 EMG
Structure of skeletal muscle
MUSCLE BELLY
Fibers
Connective tissue
TENDON
Linear motion /translation/
translational movement –
a movement along a straight
or curved pathway
tram on straight track
 Angular /rotational motion -
motion around some point
(it occurs about an imaginary
line called the axis of rotation)
tram on curved track
When force in not enough …
Task:
You are given a sealed tin of paint and a screw
driver, and then you are asked to open it.
How will you open the tin?
Opening a paint tin with a short screw driver
Opening a paint tin with a long screw driver
 In human body – only rotational movements occur!!!
 The muscles create the moment of force that turn our
limbs.
The line of action of a muscles force is along
its attachements (tendons).
The line of action of the muscle force
is some distance from the joint axis (d)
Muscle moment arm length
 Moment arm = perpendicular distance between the
muscle and the point of rotation.
Moment of force
Moment is the turning effect of a force
M = d * F [Nm]
Moment = force (F) × perpendicular distance (d)
(moment arm*)
* the shortest distance from forces line of action to the axis of rotation
How to assume the moment of muscle force???
 The conditions for static equilibrium allow us to
estimate the forces our muscles produce.
 If an objects is at rest it is described as being in a
state of static equilibrium.
THE MUSCLES OF UPPER LIMB
Muscles of shoulder
Muscles of forearm
Muscles of hand
FQ
No appreciable change in length
of the muscle (static contraction)
The mean values of max moment of force
T – trunk
Fl – flexor
EX - extensor
SH - shoulder
El – elbow
MUSCLE GROUP
X [Nm]
FL T
M
256,3
F
176,4
M
588,1
F
416,6
M
145,1
F
69,3
EX SH M
110,7
F
56,5
M
89,8
F
48,6
M
58,8
F
31,2
EX T
FL SH
FL El
EX El
Hand grip
The Motor Unit
 The smallest functional unit to describe the neural control of the
muscular contraction process is called a Motor Unit.
 Single motorneuron & muscle fibers it innervates
EMD
Moment of force [Nm]
Rate of muscular force production =
Time of contraction vs. force
time [s]
Electromechanical delay
Muscles are made up of many muscle fibres. The muscle fibres can be
SLOW TWITCH FIBRES or FAST TWITCH FIBRES.
We all have both types in our muscles in different quantities, and
what we have appears to be handed down from our parents in our
genes.
SLOW TWITCH FIBRES are deep red in colour and they have a good
oxygen supply to the working muscle (runners). These muscles
contract slowly but they can work for long periods of time.
FAST TWITCH FIBRES are white and work much more quickly, but
they also tire more quickly (drummers, swimmers).
Percussion playing =
high speed motion which uses fast twitch fibers
Muscle Fatigue
 Reduction in muscle force production
 !!!! Awkward posture or prolonged muscle
contraction can lead to muscle fatigue