4 Processes which initiate movement

All athletic movement feeds of energy released through complexed chemical changes in the metabolism – through the krebs cycle.

1. Neuromuscular control of movement 2. Muscular contraction3. The re-synthesis of energy through the three energy systems4. The activity of the cardio-respiratory system (heart, lungs and circulation) during exercise as a support of the energy production process.

Krebs cycle

1. Neuromuscular control of movement.

Movement by complexed system of muscles and levers

LEVERS are the bones which form a rigid frame

Muscles are tissues that change shape to engage force to move the levers and allow movement to take place.

These muscles need signals to react and contract or relax –

Muscle force and muscle specific to determine the reaction in a certain direction

CNS PNS

Control of skeletal muscular system from the CNS

Motor neurons conduct the frequency for contraction or relaxation to in some cases hundreds of muscle fibers depending upon the size of the muscle group.

Nerve fibers – crucial trainability

Excitable reacting to changes in their electrical potential

The nerve is membraned controlled which ensures electrical changes – in sodium and potassium ions.

Nerve stimulation creates action potential –Transmitting the signal down the nerve to the muscle fibers

FORCE of contractions is regulated by the number of motor units recruited and the rate at which they are stimulated

MUSCLE controlled by nerve response

Motor Units and Recruitment

motor unit

characteristics of contraction speed

type of muscle fibres the motor neuron serves

Training intensities and physiological make up of the training cycles determines motor unit recruitment.

Type of motor unit Metabolic

characteristics

Rate of contraction Force created Fatigue rate

TYPE I Oxidative Slow Twitch Small Low

TYPE IIa Oxidative/Glycolytic Fast Twitch Medium Low

TYPE IIb Glycolytic Fast Twitch Large High

Determining fibre type

Table 1: Characteristics of the Three Muscle Fibre Types

Fiber Type Slow Twitch (ST) Fast Twitch A (FT-A) Fast Twitch B (FT-B)

Contraction time Slow Fast Very fast

Size of motor neuron Small Large Very large

Resistance to fatigue High Intermediate Low

Activity used for Aerobic Long term anaerobic Short term anaerobic

Force production Low High Very high

Mitochondrial

densityHigh High Low

Capillary density High Intermediate Low

Oxidative capacity High High Low

Glycolytic capacity Low High High

Major storage fuel Triglycerides CP, Glycogen CP, Glycogen

Movement

•Muscle fibres are stimulated electrically•Energy is needed to realise movement of the protein filaments•ATP is the breakdown of the high energy compound

Muscular contraction and training

•Physiological changes in the muscle after training•Tissues •Nervous system sensitivity•Correct cycling movements•Training tools •SRM•Power-cranks•Adaptations in speed and accuracy

ATP - PC Lactacid Aerobic

Alactic(without lactate build up)

Glycolysis(breakdown of glycogen)

Oxygen availability?NO YES

Lactic acid

O2 and

CO2

FAT + protein metabolism (with O2)

Anaerobic (without O2)

•Three energy systems for regenerating the ATP

System Fuel used Chemical reactions

required

Speed of replacement Quantity of store

ATP -PC Phosphocreatine One simple reaction,

within muscle cells

VERY FAST VERY small (<10secs)

Lactacid Glycogen Twelve enzyme

reactions, within

muscle cells

FAST Medium (approx 1hour)

Aerobic Glycogen

FAT/Protein

Complex set of enzyme

aided reactions.

Transfer of oxygen from

air-lungs-circulation-

muscles

SLOW

SLOWEST

Medium (approx

2hours)

LARGE (weeks)

.Characteristics of the three energy systems.

Examples for cyclists track or road program, 200m sprint – ATP-PC – backed up partially by lactacid – anaerobic glycolysisEndurance races – energy at a slower rate – aerobic metabolism, fat burning still able to produce a sprint at the end....

Cardio-respiratory system – detecting chemical changes

Cardio – Respiratory function At rest During exercise

Heart Rate (BPM) 30-55 120-200

Stroke volume (amount of blood

pumped by the heart per/ beat

60-80 millilitres 120-180 millilitres

Cardiac output (amount of blood

pumped by the heart per/minute

4-5 litres 20-30 litres

Ventilation (amount of air breathed

per/minute

8-12 litres 120-180 litres

Example values of selected cardio-respiratory functions at rest and during exercise for top-sport athletes.

Key to endurance performances and long term adaptations in training

Cardio- respiratory changes from training

•Cardiac output can be improved significantly through endurance training•Heart rate at maximum work rates – heart rate accuracy and trends•% changes in VO2max potential

•Endurance training to increase the size and number of mitochondria enabling a greater oxidation of glycogen.•The quantity of glycogen and aerobic enzymes stored in the muscles increases and there is a greater muscle capillarisation after training. In addition, the body is able to use proportionally more fat as a fuel, there by conserving valuable muscle glycogen stores. This is particularly important when considering weight loss and nutritional needs for competitive cyclists.

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Applied physiology to cycling and energy systems