Human Sport and Motor Control
Week 1: Introduction + Background Material
Core Topics
1. Degrees-of-freedom problem: At multiple levels, more than one option for a motor
process is available: the degrees of freedom problem is a problem because science wants
to predict. Redundancy is biologically clever because there is immediate compensation
should part of the system fail suddenly. The degrees of freedom problem is a blessing
since trainers and therapists can mobilize remaining capacity when local injuries occur!
2. Sequencing: A sequence is a combination of fundamental movement skills and
movement elements to enable the body and/or objects to move in response to a
stimulus. The purpose of sequence control is to maintain the predetermined order at
which the motors are forced to start or stop. Motor sequence learning is a process by
which a sequence of movements comes to be performed faster and more accurately
than before. Examples are speech errors and coarticulation (stroop). Theories are:
3. Perceptuomotor integration: feedback and expected sensory consequences
4. Motor learning: refers broadly to changes in an organism's movements that reflect
changes in the structure and function of the nervous system. Motor learning is "relatively
permanent", as the capability to respond appropriately is acquired and retained. Temporary gains in
performance during practice or in response to some perturbation are often termed motor
adaptation, a transient form of learning. Research in Neuroscience and behavioral (feedback etc.)
Important Theories
1. Information Processing Theory: Sport is conducted within three subsequent processes:
Perception, Decision, Action and occur in a linear fashion. You might divide each of those three
processes in more detailed underlying processes (for each sport different)
2. Coordination Theory: degrees-of-freedom-problem: we have so many different possibilities to use
our limbs joint etc the question arises how we choose to use which coordination for which situation.
Theory suggests that people use biophysical optimization principles (work, muscle stress, motor
command) and task-constraint satisfaction (minimal spatial error costs, minimum travel costs)
3. Dynamical Systems Theory: you don’t have to control your movement for each millisecond when
it is part of a dynamic cycle, flowing kinetic energy. Those dynamic systems can influence each other
4. Ecological Psychology: The relation between perception and action can be direct: immediate
coupling of a stimulus in the environment to a movement you perform, environment and human
interact as one unit
Neuroscience
From muscle contraction to action: movement can be described on the levels of fibres, muscle,
antagonists, and action.
Fibres: sports increase the number of actine-myosin bridges and non-use results in muscle atrophy,
when warming up, the muscle temperature and metabolism increase with help of the contractile
proteins actine and myosin (supply of energy through breakdown of glycogen).
Muscles: muscles as springs (federn) (jumping), activities require oscillatory movements
(running, swimming), oscillatory movements need energy, adjustment and monitoring,
experts also need to understand the laws of motion (e.g. mentioned by Isaac newton),
boxers know how to exploit their mass-spring system to generate high forces at top speed
→ muscles make up of 40-50% of body mass, highly complex architecture: movements can be
performed by contractions of many muscle combinations (=redundancy), experts know to exploit
redundancy
→ sensory information originating from muscles contractions provides proprioception, i.e.
awareness of one’s own body position in the world, which is essential for many sports
,Motor cortex: involved in voluntary movement, in frontal lobe anterior to central sulcus:
Primary motor cortex is located in the precentral gyrus and arranged such that different parts of the
region are associated with motor control of different parts of the body (motor map). Most of
neurons that travel from the primary motor cortex carrying signals regarding movement will enter
one of two major motor pathways:
→ Corticospinal tract: carries signals to spinal cord to cause movement of the body
→ Corticobulbar tract: carries signals to brainstem to cause movement of neck/head/face
Nonprimary motor cortex: divided in two regions
→ Supplementary motor cortex: involved in the execution of sequences of movement, the
attainment of motor skills and the selection of movement based on incoming sensory information
→ Premotor cortex: contributes about 30% of the neurons that enter corticospinal tract but seems
to be active during planning rather than executing movement
Knee-jerk reflex: occurs at the level of the spinal cord, monosynaptic reflex
(direct connections between sensory and motor neurons without any
neurons in between), brain is not involved, inhibitory interneuron inhibits
hamstring, so the quadriceps muscle gets moves (opponent)
Basal ganglia: group of structures found deep within the cerebral hemispheres and the brainstem
that include the caudate and putamen (striatum), globus pallidus, substantia nigra (both multiple
nuclei), subthalamic nucleus
→ Information comes from cerebral cortex and first goes to
caudate or putamen, which are the main input nuclei, whereas
the globus pallidus and substantia nigra are the main output
nuclei (send information from basal ganglia to cerebral cortex),
mostly over thalamus and nuclei by the brain stem.
→ the basal ganglia do not cause movement independently but rather influences activity in other
areas of the brain such as the motor cortex: different circuits in the basal ganglia enhance or inhibit
movement, according to this theory the main output of the basal ganglia is inhibitory, and neurons
of the globus pallidus constantly inhibit the thalamus to inhibit unwanted movement
→ direct pathway: silencing neurons in globus pallidus which therefore inhibits the inhibition of the
thalamus, allows movement to occur
→ indirect pathway: increase suppression of unwanted movement (subthalamic thalamus)
Parkinson’s: degenerative disease, impairment in movement, low levels of dopamine in the basal
ganglia, caused by death of dopamine neurons in the substantia nigra
Huntington’s disease: chorea (involuntary, spasmodic movements), impaired coordination and
balance, muscle rigidity, difficulty speaking/swallowing, cognitive symptoms (dementia and
depression), incurable and fatal
→ mutation in a single gene, impaired basal ganglia, neurodegeneration
Motor pathways
The lateral pathway: responsible for voluntary, controlled movement
→ lateral corticospinal tract (distal muscles = more far away like lower arms/legs, hand/feet)
→ anterior corticospinal tract (proximal muscles = close to body like shoulder, upper arms, and legs)
→ rubrospinal tract
The anterior medial pathway: mainly controls axial muscles for balance and posture
→ vestibulospinal tract (medial/lateral)
→ reticulospinal tract (puntine/medullary)
→ tectospinal
→ anterior corticospinal tract (proximal muscles, voluntary)
, Reading Assignment
Dorsolateral prefrontal cortex: plans for movement, cognition
Premotor cortex: action, externally triggered
Supplementary motor cortex: action, internally triggered (generated from memory)
Parietal cortex: perception of space and location of limbs, Integrating position of eye and hand
Primary motor cortex: movement of muscle
Striatum: adjusting movement speed
Basal ganglia: inhibitory, via thalamus, dopamine, acts as brake
Cerrebellum: excitatory, sensorimotor, feedforward, learning, timing, stifness, smoothness, via
thalamus, coordination of movement, proprioceptive feedback, balance
Brainstem: reticular formation for visual information and signals of the vestibular organ are
intergrated, relating vision to balance
Alfa-gamma complex at the spinal level: samen --> maintain spindle sensitivity
Four motion recording systems
Movement-Position Recording Optotrak: tool with three calibrated cameras (comparable to insects
eye), two are horizontal and one is vertically orientated: 200 times per second movement can be
measured by measuring infrared light: IREDs are glued to person’s skin and their infrared is detected
by the camera: position changes in time, allows 3D movement-position recording
Movement-Acceleration Recording VibSensor: Movement acceleration recording and analysis tool
on mobile phone: acceleration changes associated w. position changes, acceleration-time function,
→ we have an acceleration sensory system in the ear (vestibular system), horizontal x, vertical y,
lateral z. Accelerometer in the device measures these three directions, e.g. during walking on the
ancle, consumption of alcohol more deviation in the lateral direction, can measure walking abilities
of Parkinson’s patients (tremors): You can measure both low frequencies and high frequencies
components of a movement and how strong these tremors are. (8Hz tremor typical for Parkinson’s)
Ground-Reaction Force Recording Forceplate: record force changes on plates that are on the
ground (you step on them) different forces on parts those plates is measured, can also be used to
measure how people maintain their balance.
Muscle-Contraction Recording EMG (Electromyography): electrical signal at the surface of the body
when muscles contract is measured with electrodes. The Raw EMG signals have to be rectified and
enveloped to see the actual movement.
Neural Activity Recording EEG (Electroencephalogram): where activities are taken place during
movement performance
Neural Activity Recording fMRI: study structure activation during movement, but movement
disturbs fMRI: can be used for finger tasks or for movement planning (motor imagery)
