At the end of this section, you will be able to do the following: 

• Describe the functions of the skeletal system 

• Describe the types of bones and their functions 

• Identify the major bones and classify them into the different types of bones Describe the types of joints 

• Describe components of a freely movable joint 

• Describe the types of freely moveable joint and their types of movement 

  • Flexion/extension 

  • Abduction/adduction 

  • Rotation 

  • Circumduction 

• Describe how the following types of movement are linked to the appropriate joint type Identify the planes and axes of the human body in relation to the types of movement

Functions of the Skeletal System

Types of Bones

Types of Joints

Types of Freely Movable Joints

Good to Know...

https://www.youtube.com/watch?v=DLxYDoN634c

Types of Joint Movement

More information:

mammothmemory.net/sports/joints/types-of-joint-movement/anatomy-and-anatomic-movement.html 

https://exrx.net/Lists/Articulations

Movement Planes and axis

Type of Connective Tissue

At the end of this section, you will gain the following:

•  Describe the characteristics of the types of muscles 

• Describe the functions of the major muscle groups 

• Explain how muscles work together 

• Explain how the skeletal and muscular systems (i.e., musculoskeletal system) work together to enable movement during exercise and sports

Types and characteristics of Muscle

Extend Your Knowledge 

Skeletal muscles are made up of individual muscle fibres. There are two types of skeletal muscle fibres, fast-twitch and slow-twitch, and they have different functions in movement. Find out more about each type of skeletal muscle fibres and the type of activity they predominantly support.

More information:

https://exrx.net/Lists/Muscle

Agonist, Antagonist and Synergist Muscles

• Muscles work in pairs or groups so that as one muscle contracts, the other relaxes to support a movement. 

• The muscle that contracts to bring about a movement is called the prime mover or agonist muscle. 

• The antagonist muscle is the muscle that relaxes to allow movement in a joint when the agonist muscle contracts. 

• There are also the synergist muscles, which assist indirectly in a movement by stabilising a certain joint or body part.

• For example, during a bicep curl, the biceps is the agonist muscle, which contracts to cause the flexion of the elbow. The triceps is the antagonist muscle. The deltoid acts as one of the synergist muscles, which contract to stabilise the shoulder joint.

Muscles Contraction

At the end of this section, you will be able to do the following:

• Describe the components and functions of the circulatory system

• Describe the pathway of blood through the heart and the rest of the body

• Explain the relationship between cardiac output, heart rate and stroke volume at rest and during exercise

Components of the Circulatory System

The heart, blood vessels and blood form the circulatory system. Its role is to transport oxygen, nutrients and other substances around the body.

Components of Blood:

Blood has the following four components:

Functions of the Circulatory System

The circulatory system keeps blood, oxygen and nutrients flowing through the body. 

Understanding Cardiac Output and Heart Rate

Effects of Exercise on the Circulatory System

At the end of this section, you will be able to do the following:

• Identify the components and show an understanding of the functions of the respiratory system

• Describe the pathway of air through the respiratory system

• Describe the process of inhaling (at rest) and exhaling (at rest)

• Explain the lung volume and capacity

• Explain how the circulatory and respiratory systems (i.e., cardiorespiratory system) work together to influence movement during exercise and sports

• Respiration, also known as breathing, is vital to daily life and functioning

• It is a complicated process in which air travels into and out of the lungs. 

• This process is supported by the respiratory system, which is a collection of organs responsible for taking in oxygen and expelling carbon dioxide. 

• The respiratory system consists of the nose, lungs and breathing tubes. 

• Its role is to supply oxygen to the working muscles and all the other body cells.

• The lungs take in oxygen and give out carbon dioxide. 

• When we breathe in, we take in air that contains oxygen. 

• Oxygen enters the respiratory system through the nasal passage (nose) and mouth. 

• Then it travels down the trachea (windpipe), which divides into the left and right bronchi in the lungs. 

• These main airways then branch into smaller and narrower airways called bronchioles, which further branch into even finer broccoli-shaped airways called alveoli, which consist of millions of air sacs.

• The gas exchange between oxygen and carbon dioxide takes place in the alveoli of the lungs. 

• The alveoli are covered in tiny capillaries (blood vessels). 

• Gases can pass through the thin walls of each alveolus and capillary.

The different COmponents and Functions

More Terms Relating to the Respiratory System

1. Tidal volume is the amount of air inhaled or exhaled during normal breathing.

2. Respiratory rate is the number of breaths taken per minute.

3. Minute ventilation is the amount of air inhaled or exhaled per minute.

   • Minute ventilation = Tidal volume × Respiratory rate (all three increase during exercise).

4. Vital capacity is the maximum amount of air that can be exhaled after inhaling as much as possible. It can be increased with regular physical activity.

5. Residual volume is the amount of air left in the lungs after exhaling as much as possible. The lungs are never empty of air.

6. Total lung capacity is the total amount of air the lungs can hold. 

   • It is the sum of vital capacity and residual volume 

Understanding the Cardiorespiratory System During Movement

 The body’s cardiorespiratory system supplies oxygen to the muscles during exercise and sports. When oxygen in the air enters the alveoli, it passes through the alveoli walls and into the red blood cells that are travelling in the capillaries. The oxygenated blood returns to the left atrium and left ventricle of the heart where it is finally sent to the rest of the body, carrying the oxygen needed by the body cells.

Deoxygenated blood from all parts of the body exits the right ventricle of the heart and is transported through the pulmonary arteries to the capillaries surrounding the alveoli. The carbon dioxide in the blood passes through the capillary walls into the alveoli. From the alveoli, it travels out of the lungs, goes through the trachea and is exhaled from the body.

At the end of this section, you will be able to do the following:

• Explain how energy can be released for muscle contraction

• Explain the role of macronutrients as energy sources for aerobic and anaerobic exercises

• Evaluate the relative contributions of the energy systems during aerobic and anaerobic exercises, including interpreting graphical representation of the relative contributions of the energy system

• Apply the understanding of training zones to improve the energy systems for performance in exercise and sports

Energy Production in Our Body

• Muscles need energy to contract and create movement. 

• Energy comes from consuming food, which is broken down in the stomach into liquid form during digestion. 

• The components in this liquid are passed into the blood and are carried to the cells for energy, growth and repair.

• During digestion, carbohydrates are broken down into glucose. 

• Muscles get most of the energy they need from the reaction between glucose and oxygen. 

• Glucose is carried to the cells by the blood, while oxygen is obtained from inhaled air and transported from the lungs by the blood.

Energy Balance

A person’s basal metabolic rate is the energy needed to be alive, awake and comfortably warm. A person’s working energy is the extra energy needed to move the body and digest food. The total energy needed depends on the following factors:

•  age

•  gender

•  body composition and size

• lifestyle

Role of Macronutrients as Energy Sources for Aerobic and Anaerobic Respiration

Food provides energy and nutrition. During digestion, food in the stomach is broken down into nutritional components in liquid form. These nutritional components, also known as nutrients, are then carried through the blood to cells, such as muscle cells for energy, growth and repair.

Different nutrients come from different foods. The body needs nutrients for energy, growth and repair. They consist of three primary macronutrients (carbohydrates, protein and fat) and small amounts of micronutrients (vitamins and minerals). The body also needs water and fibre.

The amount of macronutrients needed by an individual depends on their level of physical activity. In exercise and sports, macronutrients are frequently discussed in terms of energy production and their role in building skeletal muscle that can be trained or stimulated to increase force production. Carbohydrates and fat are primarily used for producing energy, while protein builds and repairs muscles.

Chloride, Potassium and Sodium mostly exist as electrolytes in body fluids, which are important for exercise and sports. 

• • regulate fluid exchange in the body’s fluid compartments, maintain a balanced exchange of nutrients and waste products

  • The required electrolyte intake depends on athlete sweat rate and electrolyte loss during exercise

  • Sodium and chloride are commonly found in food as salt

  • Potassium is commonly found in vegetables and fruits

Calcium and phosphorus play key roles in the formation of bones, with more than 90 per cent found in our skeletal system

• • Calcium is needed for muscle contraction, and for the synthesis and breakdown of glycogen to produce energy

  • Phosphorus is needed to regulate the release of oxygen to the muscles during exercise and sports

  • commonly found in milk and dairy products

Nutrition for Different Phases of Physical Activity

Consuming nutrients at the right time supports physiological adaptations to exercise and enhances physical performance. Nutrient timing recommendations vary among athletes in a sport and across different sports.

Before Activity

• meeting the daily nutritional intake would be enough for most athletes

• for those in endurance sports, providing working muscles with carbohydrates is important for sustained performance 

• endurance athletes thus use carbohydrate loading before long events to boost the stores of muscle glycogen in their bodies

During Activity

• during prolonged physical activity, the body uses up its available stores of muscle glycogen and relies on blood glucose supplied by the liver 

• as liver glycogen stores are depleted, low blood glucose levels can impair the athlete’s physical performance and may cause anxiety, nervousness and tremors. 

• consuming glucose during long-duration physical activity (over 60 minutes) has been shown to reduce the rate of muscle and liver glycogen depletion, maintain normal blood glucose concentrations, delay fatigue and improve endurance performance

• in recent years, studies have suggested that consuming protein during physical activity may help prevent damage to muscle tissue and promote recovery.

• however, athletes should be careful about consuming food during competitions, as this may result in gastrointestinal upset and hamper their performance. 

• therefore, it is vital to try it in a practice situation that simulates competition

After activity

• sufficient daily carbohydrate intake is necessary to replenish muscle glycogen levels after training, and to help promote skeletal muscle repair and growth

• some studies suggested that more muscle glycogen is replenished when carbohydrates are consumed within 30 minutes after exercise than when they are consumed within two hours. 

• other studies have suggested that consuming protein within three hours after exercise can significantly increase muscle repair

• consuming a combination of protein and carbohydrates can help promote greater recovery of muscle glycogen as well as muscle repair and growth

Energy Systems

The body has two main types of energy systems that provide energy to the body to carry out an activity.

1. Aerobic energy system

   • Aerobic respiration is the process by which cells release energy from glucose in the presence of oxygen

   • When oxygen combines with glucose inside the cells to release energy, the muscles can then contract to create movement

   • Some of the energy is converted to heat, which is dissipated by perspiration

   • Carbon dioxide builds up and is carried away by the blood and eventually exhaled from the lungs

   • Water is also produced and carried away by the blood, with some excreted through the lungs and urination

Glucose + Oxygen --> Energy + Carbon Dioxide + Water

2. Anaerobic energy system

   • Anaerobic respiration is the process by which cells release energy from glucose without the presence of oxygen

   • With no oxygen available, glucose is broken down to produce energy and lactic acid

   • The energy enables the muscles to contract, producing movement while some of it is converted to heat.

   • After about a minute, lactic acid builds up. This causes muscle fatigue and affects performance until it is removed. 

   • The muscles need extra oxygen to get rid of the lactic acid. This extra oxygen required is called the oxygen debt. 

   • After the high intensity exercise, a period of deep breathing is required to repay the oxygen debt.

There are Two Types of Anaerobic Energy System

Lactic acid system

• Energy is released to enable the body to engage in high-intensity work for a period of time, e.g., when running a 400 m race.

• It is the dominant source of energy production during high-intensity activity lasting about 30 to 60 seconds.

• Lactic acid accumulates in the muscles when exercising at an intensity higher than the anaerobic threshold, eventually resulting in fatigue.

• Lactic acid is removed during recovery from exercise as sufficient oxygen becomes available.

 Creatine phosphate system

• Energy is released rapidly and is required by the body in short bursts of maximal work, e.g., when sprinting in a 100 m race.

• Enough energy is stored to allow for an immediate release of energy to fuel about 8 seconds of high-intensity activity.

• Subsequently, recovery is needed to replenish the system.

• Energy is released more rapidly by this system than the lactic acid system.

Training the Energy Systems

The heart rate is an indicator of which energy system an individual is using. The more intensely they exercise, the faster their heart beats. The closer their heart rate is to their maximum heart rate (MHR), the more likely it is that they are using the anaerobic system. To recall, the estimate MHR = 220 - your age.

The heart rate is an indicator of which energy system you are using

• 80% of your MHR, in the anaerobic training zone

• 60–80% of your MHR, in the aerobic training zone

• below 60% of your MHR, has little effect on improving your energy systems

For aerobic training:

1. Aerobic training improves cardiovascular endurance

2. As a general guide, training should occur at least three times a week to improve the aerobic energy system

   • This involves engaging in activities that are of low (about 60–70% of the MHR) to moderate (about 70–80% of the MHR) intensity for a long duration

3. Training at close to 80% of the MHR will help increase the anaerobic threshold, leading to an overall improvement in fitness and endurance (thus, improving aerobic energy system)

4. The anaerobic threshold is the exertion level between aerobic and anaerobic training. During exercise, the anaerobic threshold is the point at which the body must switch from using the aerobic energy system to the anaerobic energy system. By increasing the anaerobic threshold, it increases the duration a person can fuel his/her body with the aerobic system and improves the pace in an endurance activity

For anaerobic training:

1. Anaerobic training improves the ability of the muscles to work without enough oxygen, and contributes to the improvement of muscular strength, muscular endurance and power

2. This involves engaging in activities that are of high intensity (above 80% of the MHR) for a short duration

3. As such training can be quite stressful to the body, training should be progressive and the sessions spaced out to allow the body to recover before the next session

4. The heart rate should be more than 80% of the MHR. 

   • For training the lactic acid system, the heart rate should be 80–90% of the MHR

   • For training the creatine phosphate system, the heart rate should be between 90–100% of the MHR

Effects of Exercise on Aerobic and Anaerobic Systems

Adaption: Aerobic Energy System

•  Cardiac hypertrophy and increased resting stroke volume

•  Decreased resting heart rate

•  Increased blood volume and haemoglobin

•  Increased stores of muscle glycogen

•  Increased capilliarisation of the muscles

•  Increased capilliarisation of the alveoli, which improves the efficiency of gas exchange

•  Increased respiratory rate (tidal volume and minute volume)

•  Increased maximum rate of oxygen consumption (VO2 Max- the maximum amount of oxygen taken in, transported and used by the body per minute)

Adaptation: Anaerobic Energy System

•  Enhanced nervous system (the network of nerve cells and fibres that transmit nerve impulses between different parts of the body), which facilitates maximum recruitment of muscles for greater force, speed and power production

•  Increased muscle size, which can result in enhanced muscular strength, power and endurance

•  Increased mass and strength of bones, ligaments, tendons, fasciae and cartilage

•  Elevated testosterone, growth hormone and cortisol levels

•  Increased cardiac output, stroke volume, heart rate, oxygen uptake, systolic blood pressure and blood flow to the active muscles

At the end of this section, you will be able to do the following:

• Define the fitness components

• Explain the importance of each fitness component for different exercises and sports.

• Apply the principles of training to manipulate the training variables in developing a training programme

• Apply the methods of training to improve the fitness components and the energy systems involved in exercise and sports

Planning a Training Programme: What to consider?

When planning a training programme for oneself or others, the following three areas should be considered:

1. profile and needs of the individual

2. physical requirements for the sport

3. strengths and areas of improvement of the individual

Principles of Training

Training is a programme consisting of intentional physical activities and exercises that are designed to help an individual reach his/her sports and fitness goals. It is based on five principles that form the acronym SPORI.