Short term effects of exercise

Skeletal System

Osteoclast Activity

Synovial Fluid

Break down the tissue to allow new growth

Thick, straw-coloured liquid that acts as a lubricant and is found primarily in the cavities of synovial joints.

Exercise increases the amount of synovial fluid.

Weight baring exercise stimulates the activity of osteoblasts and supresses osteoclast activity, maintaining a healthy bone density.

Muscular System Responses

Muscle Fibre recruitment

Blood Flow to Woking Muscles

Micro-tears

Temprature

First, slow twitch (type 1) muscle fibres are brought into action, then fast-twitch muscle fibres (type11a and type 11x).

High intensity = type 11x

Medium intensity = type 11a

Low intensity = type 1

Vascular Shunting

shunt blood and sweat

increases blood flow to muscle

decreases blood flow to digestive system

Muscle fibres will contract and relax against each other, resulting in microscopic tears to the fibres.

When you rest after the activity your body heals and uses proteins to fill the gaps in the tears.

During exercise all muscles require energy, gained from fuels such as carbohydrates and fats

One of the products is heat. As the muscles warm up, blood circulating through the muscles is also warmed resulting in a rise in the body's temperature.

The amount of heat your muscles produce is related to the amount of work they perform: the more exercise, the more heat they produce.

Cardiovascular System Responses

Cardiac Cycle

Anticipatory increase in heart rate

Cardiac output

Changes in blood pH

Heart rate

Stroke volume

Arteriovenous oxygen difference (a-v02 diff)

Speeds up to meet the demands of the exercise

Factors that changes as a result:

heart rate increases

amount of blood increases

blood pressure increases

waste products are removed

blood is diverted

vasoconstriction

vasodilation

Occurs before the start of exercise

Heart rate can be changed by neurotransmitters such as adrenaline and noradrenaline, released from the brain.

Before exercise, the heart rate increases and the subsequent increase in blood flow has already begun to supply oxygen and nutrients to the working muscles

The volume of blood pumped out of the heart in 1 minute

expressed as Q

Is equal to heart rate multiplied by the stroke volume

The amount of blood pumped by the left ventricle in one contraction.

Increases during exercise

Goes from 70-80ml per beat to around 110ml

Blood pressure

Determined by two factors:

cardiac output

the resistance offered by blood vessels

Higher exercise intensity = greater rise in heart rate

Changes according to the body's needs

Increases during exercise to deliver extra oxygen to tissues and remove carbon dioxide

The sympathetic nerve speeds up the heart

The vagus nerve (parasympathetic nerve) slows down the heart

Stroke volume during maximal exercise does not increase - left volume is already full to capacity

The pH of blood is generally between 7.2 and 7.5

During exercise - we go towards being more acidic due to waste products such as carbon dioxide and lactic acid

blood pH

Arterial blood

Venous blood

bright red in the colour due to high concentrations of oxygen

when the blood leaves the heart

Darker red due to high concentrations of carbon dioxide

delivered O2 to the muscle

At rest - smaller gap

During exercise - bigger difference

Respiratory

Control of breathing rate

Respiratory muscles

Additional muscles that aid breathing

Tidal volume

Minute volume

Oxygen Dissociation Curve

chemical - chemoreceptors

neural control - respiratory receptors

Diaphragm

intercostal muscle

Sternocleidomastoid

External Obliques

Internal Obliques

Rectus Abdominus

Transverse Abdominus

The amount of air ventilated in or out of the lungs in one breath

Trained athletes achieve the required alveolar ventilation by increasing tidal volume and only minimally increasing breathing rate.

At a low to moderate exercise intensity, tidal volume and breathing rate increase proportionally

At a high exercise intensity, tidal volume reaches a peak so any further increase in minute volume requires an increase in breathing rate

Partial Pressure

Shows the relationship between the percentage of oxygen saturation of blood and the partial pressure of oxygen

pressure applied by a single gas in a mixture of gasses

Increased temperature and lower blood pH concentration affect the oxygen dissociation curve

In the lungs, the partial pressure of oxygen is high therefore haemoglobin has a high affinity

Neuromuscular System

Motor Neurons

Sensory Neurons

Carry information from our central nervous system to out muscles

Carry information from our skin to our central nervous system

Muscle spindles and Golgi tendon organs provide sensory information about the intensity of exercise, allowing smooth, coordinated movement patterns

endocrine System Responses to Short Term Exercise

Detect changes in the environment

Thermoreceptor

Baroreceptors

Chemoreceptors

Carbon dioxide

Hydrogen

Lactic acid

Detects change in temperature

Detects change in blood pressure

Oestrogen

Cortisol

Testosterone

Human Growth Hormone

Noradrenaline

Adrenaline

Female sex hormone which controls puberty and strengthens bones

Exercise can lower levels of circulating oestrogens

Increases seretonin

Modifies the production and the effects of endorphins

Stress hormone

Helps control blood pressure and metabolism

Increases blood sugar levels

Anticipatory rise

Vasoconstriction and vasodilation

Increases heart rate, breathing rate and metabolic rate and improves the force of muscle actions

Acts as a neurotransmitter

Low levels are associated with depression

Acts to increase force of skeletal muscle contraction and the rate and force of contraction

Involved in the development of muscle tissue and muscular strength

Increases the number of neurotransmitters

Encourages muscle growth

Increases levels of human growth hormone (HGH)

Stimulates general body growth and the lengthening of bones in particular

Energy Systems

During exercise, the body does not switch from one energy system to another - energy is derived from all systems at all times. However, the emphasis of which is used is dependant on intensity

ATP - CP

Lactate system

Aerobic

high intensity

PC is broken down, releasing both energy and a molecule (which is then used to rebuild ATP). The enzyme that controls the breakdown of PC is called creatine kinase.

The ATP-PC system can operate with or without oxygen, but because it does not rely on the presence of oxygen it is anaerobic.

The ATP-PC system can sustain all-out exercise for 3-15 seconds.

ATP Production

  1. ATP if formed when adenosine diphosphate (ADP) binds with a phosphate
  1. Energy is stored in the bond between the second and third phosphate groups
  1. When a cell needs energy it breaks off the phosphate for adenosine diphosphate (ADP)

Medium intensity (just after ATP-PC)

Glycolysis = the breakdown of glucose

It consists of a series of enxymatic reactions. The end product of glycolysis is pyruvic acid which is used in a process called the Krebs cycle or converted into lactic acid.

Krebs Cycle

  1. Anaerobic glycolysis occurs at times when energy is required in the absence of oxygen
  1. It involves the breakdown of glycogen to form ATP plus lactate
  1. The build up of lactate in the muscles stops the use of this energy after 40 to 60 seconds
  1. Pyruvic acid and hydrogen is formed. A build up of hydrogen turns the muscle acidic so NAD molecules remove hydrogen
  1. NAD is reduced to NADH which gets rid of the hydrogen during the electron transport chain to be mixed with oxygen to form water
  1. If there is insufficient oxygen, NADH cannot release the hydrogen and they build up in the cell.