PDHPE

Energy Systems

• Fuel the body and are essential for physical activity.
• The three main energy systems are the ATP/PC system, the lactic acid system, and the aerobic system.

Alactacid System (ATP/PC)

• Provides immediate energy for high-intensity, explosive activities lasting up to 12 seconds, such as sprinting, jumping, or heavy lifting.
• It is anaerobic, meaning it doesn't require oxygen.
• It does not produce lactic acid.

Adenosine Triphosphate (ATP)

• Main energy currency for muscle contractions.
• Stored in small amounts in muscles, lasting only 1-2 seconds during high-intensity activity.
• Acts as a "battery".

Phosphocreatine (Creatine Phosphate) (CP)

• High-energy molecule stored in muscles that quickly regenerates ATP.
• Allows intense effort for an additional 8-10 seconds.
• Acts as a backup battery.

ATP/PC System Functionality

• Initial Energy (1–2 seconds): Uses stored ATP for very short, explosive efforts.
• Next Phase (3–12 seconds): Uses creatine phosphate (CP) to regenerate ATP quickly.
• Transition to Other Systems: Shifts to the lactic acid system (anaerobic glycolysis) when CP stores are depleted after 12 seconds.

Fuel Source

• Creatine phosphate (CP) is stored in the muscles and quickly used to regenerate ATP during short bursts of intense activity.
• Small amount of ATP stored in the muscles is used up within 1-2 seconds during intense activity.
• CP recharges ATP enabling muscles to function for short, intense efforts.
• Once the creatine phosphate runs out, the body needs to switch to other energy systems (like the lactic acid system) to keep producing ATP for longer activities.

Recovery and CP Replenishment

• CP is replenished during rest periods using oxygen.
• Partial recovery takes 2 minutes, and full recovery takes 3-5 minutes.
• Short breaks during intense activity can improve performance in multiple bursts of high-intensity exercise.
• The ATP/PC system can begin to replenish its stores of ATP and CP while the body is in the lactic acid system, due to ATP production during lactic systems.

ADP (Adenosine Diphosphate).

• ATP becomes ADP when used for energy.
• ADP is a "drained battery."
• Creatine phosphate (CP) donates a phosphate group to ADP, turning it back into ATP (recharging the battery).
• CP is used up very quickly (within 12 seconds), and takes around 2 minutes for your body to partially restore it.

Creatine Loading

• Rapidly available, energy-producing substance used during high intensity activity.
• Binds phosphate to form creatine phosphate, essential to regenerate ADP to ATP and provide energy for muscular contractions.
• Natural substance found in meat and fish, classified as a food supplement.
• Boosts performance when taken with high carbohydrate diets in most studies.
• Supplementation of 20 grams per day over five to seven days each week can improve performances from 1-5% and up to 15% on repeated sprint type activities.
• Side effects include weight increases, elevated heart rate, and dehydration, causing cramping in hot, humid conditions.

Lactic Acid System - Anaerobic Glycosis

• Lactic acid is a by-product produced when the body breaks down glucose for energy in the absence of sufficient oxygen.
• Occurs during anaerobic glycolysis - generating energy without relying on oxygen.
• Accumulates during high-intensity exercise, leading to the burning sensation in muscles and fatigue.
• Backup energy source providing sustained high-intensity effort for 12 seconds to 2 minutes, eg 400m sprint and weightlifting sets.
• Provides energy when the ATP/PC system is depleted.

Lactic Acid Production

• The body can't fully break down glucose when oxygen is in short supply.
• Glucose is converted into ATP, but results in lactic acid.
• The more intense the effort, the greater the amount of lactic acid produced.

Recovery from Lactic Acid Build-Up

• More oxygen is accessible when you slow down or rest, helping clear out the lactic acid.
• The body recycles lactic acid, turning lactic acid into lactate.
• Lactate is then either used by your muscles for energy or sent to the liver, where it can be converted back into glucose (the Cori Cycle).

During Exercise

• Initial Energy: The lactic acid system begins to produce ATP when the ATP/PC system runs out after 12 seconds.
• Glucose Breakdown: Glucose or glycogen is broken down to create ATP, providing energy for continued effort.
• Lactic Acid Production: With insufficient oxygen, glucose is only partially broken down, and lactic acid begins to accumulate causing fatigue and muscle discomfort.

Transition Between Energy Systems:

• First 12 Seconds: The ATP/PC system provides energy for explosive movements.
• 12-120 Seconds: The lactic acid system takes over to produce ATP for continued effort.
• Beyond 2 Minutes: The body gradually shifts to the aerobic energy system, which uses oxygen for sustained activities.

Lactic Acid System Functionality

• Fuel Source: Uses glucose, which is the sugar circulating in the bloodstream and is used immediately for energy, or glycogen (stored form of glucose)
• Glycolysis (Anaerobic process): Process of breaking down glucose or glycogen without the use of oxygen, producing lactic acid as a by-product.
• Energy Production: Provides rapid energy for activities like 400-meter sprints or weightlifting sets, but lactic acid accumulation contributes to muscle fatigue and discomfort.

Aerobic System

• Uses oxygen to produce energy over an extended period.
• Physical activity lasting more than a couple of minutes requires the presence of oxygen to ensure the continuation of muscular contraction.
• Oxygen gradually becomes available to the muscles.
• The aerobic pathway becomes the predominant supplier of ATP.
• Process of fuel degradation is called aerobic metabolism uses glucose and fat (and sometimes protein) are broken down in the presence of oxygen to produce ATP.
• Lactic acid does not accumulate because oxygen is present.

Functionality

• Fuel Sources: Carbohydrates (glucose or glycogen), fats (fatty acids), and proteins (during long-duration activities).
• Oxygen Requirement: Oxygen is required to fully break down glucose, fatty acids, or proteins to produce ATP in a process called aerobic metabolism.

Efficiency Of System

• ATP Yield: Very high - one glucose molecule produces about 36 ATP.
• Speed: Slower than the anaerobic systems, it takes time to deliver oxygen and fully metabolise fuels.
• Duration: Virtually unlimited as long as oxygen and fuel sources are available.

Characteristics

• Main Energy System: Used for activities longer than 2-3 minutes.
• Fatigue Resistance: The body can sustain energy production for hours, provided fuel and oxygen are supplied.
• By-products: Water and carbon dioxide, which are easily removed by breathing and sweating.
• Restoration: Recovery involves replenishing glycogen stores and maintaining oxygen availability.
• Anaerobic threshold - Level of o2 consumption where there is a rapid increase in blood lactate

Aerobic Training

• Uses the aerobic system as the primary energy source.
• Targets the cardiovascular system, improving heart and lung function.
• Moderate-intensity exercise sustained over an extended period, enhancing endurance and overall fitness.
• Includes continuous, fartlek, aerobic interval and circuit training methods.

Aerobic Training Types

• Continuous training: Steady, consistent pace of exercise without rest intervals, improving cardiovascular endurance and stamina.
• Fartlek training: Blends continuous exercise with interval traning, alternating between high-intensity effort and lower-intensity recovery.
• Aerobic interval training: Alternates between periods of high-intensity exercise and lower-intensity recovery or rest, enhancing both endurance and speed.
• Circuit training: Completes a series of different exercises in a sequence, combining aerobic and strength training.

Anaerobic Training

• Uses high intensity work with limited recovery to develop systems of energy supply that function without oxygen.
• Shorter duration than aerobic training, less than two minutes.
• Effort is maximal and followed by short rest periods without full recovery of systems that supply energy.
• Seeks to enhance systems that supply energy under periods of intense activity while developing greater tolerance for the lactic acid.
• Breaks down glucose in the body without using oxygen.
• Short intervals of high intensity exercise is required .
• Team sports combine anaerobic energy production & aerobic recovery .
• High intensity interval training (HIIT) lasting 30-60 seconds at 100% - 120% of VO2 max
• Increasingly favoured as a training method over low intensity aerobic trainig for both fitness and health reasons

Anaerobic Interval Training

• High-intensity workout that alternates between short bursts of intense exercise and rest.
• Improves the anaerobic energy system.
• Intense intervals rely on energy sources without oxygen and are typically 20 seconds to a couple of minutes, followed by rest.
• It can improve speed, power, and overall athletic performance and is effective for burning calories and building muscle.
• Rest periods may be 10 seconds to 2 minutes, the key is to allow enough recovery to perform well in the next interval while still challenging your anaerobic system.

Flexibility Training

• Improves range of motion and prevents injury.

Types of Flexibility Training

• Static: Holding a stretch without movement for 30 seconds.
• Ballistic: Bouncing into a stretch, used less due to injury risk.
• PNF (proprioceptive neuromuscular facilitation): Contracting and relaxing muscles to increase flexibility.
• Dynamic stretching: Controlled movements that gradually increase reach and speed, like sport specific arm circles during warm up.
• Dynamic stretching benefits are due to elevated muscle and body temperature, and can be attributed to simulation of the nervous system and decreased inhibition of antagonist muscles.

Strength Training

• Improves muscular strength, endurance, and power by using resistance against muscle contractions through different types of resistance, leading to increased muscle mass, strength, and overall physical performance.

Strength Training Examples

• Free Weights Training: Uses unattached weights like barbells, dumbbells, and kettlebells, like Deadlifts.
• Fixed Weights Training: Uses machines that control movement paths like a Leg Press Machine.
• Isometric or static: Application of force without the muscle changing length like planking, doesn't increase strength through the full range of motion of the joint
• Dynamic or isometric : Muscle length changes as the resistance moves through the range of movements (concentric or eccentric)
• Isokinetic: Specialised machines adjust the resistance according to the force exerted to ensure resistance remains equal throughout the range of movements. Elastic Resistance training: Uses resistance bands to create tension in different movement patterns eg Resistance Band Rows.

Principles of Training

• Guidelines used to design an effective training program, ensuring progress safely and efficiently to fitness goals.

Progressive Overload Training

• Gradually increasing intensity, duration, or frequency of exercise to challenge the body, ensuring continued progress without causing injury.
• Overload above a threshold stimulates adaptive responses.
• Intensity, duration and frequency = training volume
• Progressive means not to cause injury (importance of periodistation and recovery)
• The ‘strain’ of overloading creates the adaptive response and as fitness improves, the strain decreases, hence the need for progressive overload to avoid plateauing

Endurance Training

• Leads to adaptations in:
  • Capillary and mitochondria number = aerobic gains
  • Increased ability to metabolise fat - glycogen sparing

Specificity Training

• Greatest gains are made when training activities replicates the movements in the game or activity.
• Training activity needs to target task requirements, energy systems, muscle group, muscle fibres and components of fitness.
• Training needs to be athlete specific to:
  • The muscles trained muscle fibre type recruited
  • The predominant energy system
  • Requirements of the athlete
  • Contraction required in the muscles
  • The type of muscle contraction (eccentric, concentric or isometric)
• Concentric: Muscle shortens
• Eccentric: Muscle lengthens under tension
• Isometric: muscle contracts without changing length

Reversibility Training

• Effects of training are reversible where training effects will be lost if a person stops exercising, decreases, or fails to train at a high enough intensity
• Rate of detraining is quicker in endurance training than resisting training
• In a 12-Week period of no training maximal oxygen uptake, cardiac output, stroke volume, heart rate and oxygen extraction all decline

Variety Training

• Introducing different exercises, techniques, and training methods will avoid monotony and prevent plateaus and maintains motivation
• Helps to maintain motivation, stimulates different muscle groups and energy systems & can be used for psychological purposes
• Prevents boredom
• Develops completely developed fitness levels with flexibility, resistance, aerobic.

Training Thresholds

• Minimum intensity of exercise required to improve physical fitness, they represent of different training zones.
• Fitness goals require working within particular intensity zones.
• Aerobic Threshold: The lowest intensity threshold required for the body to improve its ability to use oxygen during exercise.
• Aerobic Training Zone: Improves endurance and cardiovascular efficiency, and lactic acid is efficiently cleared.
• The intensity range where the body remains predominantly aerobic but begins to work harder. Anaerobic Threshold (Lactate Inflection Point - LIP): Before the body transitions to predominantly anaerobic energy production accelerating glycolysis (conversion of glucose to glycogen and glycogen to pyruvic acid), increasing use of fast-twitch muscle fibers .

Heart Rate (HR) Calculation

• Max HR = 220 - age (e.g., for a 20-year-old: 220 - 20 = 200 bpm).
• Aerobic threshold (70%): 140 bpm.
• Anaerobic threshold (85%): 170 bpm.

Progression Between Systems

• Body uses oxygen (aerobic) at lower intensities.
• When intensity increases, oxygen delivery cannot meet demand, and energy is produced anaerobically, leading to lactic acid accumulation.
• Endurance athletes train in the aerobic zone and train near the anaerobic threshold occasionally to improve lactate tolerance.
• Strength training thresholds about the intensity and volume of resistance that optimally trains either strength or endurance (not heart rate or lactate accumulation).

Warm-up

• Variety, training thresholds and warm-up and cool down
• Increase cardiac output and blood flow to skeletal muscles
• Increase muscle temperature which elevates muscle activity
• Ensure mobility around the joints - dynamic stretching
• A dynamic warm-up involves movements such as repeated lunging, squatting, and sprinting
• Routines should follow a progression from general activity to more specific movements at higher intensities

Cool Down

• Variety, training thresholds and warm-up and cool down
• Return ‘pooled’ blood from the exercised skeletal muscles back to central circulation
• Return HR etc to resting levels

Recovery Strategies

• Fatigue is the point where the athlete is unable to maintain power or force output during repeated muscular contractions.
• Fatigue Includes peripheral fatigue (muscular function) and central fatigue (CNS’s ability to recruit motor units for contraction).
• Fatigue becomes problematic without adequate rest and recovery (becomes overreaching and overtraining)
• Training intensity and nutrition have biggest impact to recovery, age, stress, level of fitness and environment also play a part.

Recovery Functions

• Restoration of body losses and changes caused by the first session to restore performance levels for the next session (water, heart rate homeostasis, reducing lactic acid build ups etc)
• Adaptive responses to the stress or stimulus provided by the session to gradually make the body become better at the features of exercise that are important for performance.

Monitoring Recovery (Objective and subjective data helps determine readiness)

• Psychological strategies, eg cool down, hydration
• Profile of mood states (POMS)
• Daily analysis of life demands for athletes (DALDA)
• Part A - general stressors
• Part B - stress reaction symptoms
• Recovery stress questionnaire for athletes (REST-Q-SPORT)
• Physiological strategies, eg cool down, hydration
• Physiological measures - heart rate, blood lactate, o2 consumption
• Subjective athlete measures - percieved exertion ratings
• Performance tests
• After period of overload and recovery tests could indicate training adaptation

Cryotherapy

• Pain Relief: Cryotherapy is often used to reduce pain and inflammation. Athletes, in particular, may use it to alleviate soreness after intense workouts or injuries.
• Recovery Enhancement: Many athletes and fitness enthusiasts believe that cryotherapy helps speed up recovery times after physical exertion. The cold exposure is thought to reduce muscle soreness and aid in faster healing.
• Skin Benefits: Some people use localized cryotherapy for skin treatments, as it can help reduce the appearance of fine lines and wrinkles, improve skin tone, and treat conditions like acne.
• Weight Loss: There are claims that cryotherapy can aid in weight loss by increasing metabolism. The body expends energy to warm itself back up after being exposed to cold temperatures.
• Mental Health: Some users report improved mood and reduced symptoms of anxiety and depression after cryotherapy sessions, possibly due to the release of endorphins triggered by the cold exposure.
• Most people can resume their normal activities immediately after a cryotherapy session - typically lasts only a few minutes.

Physiological improvements

• nervous system and muscular hypertrophy
• Nervous system is largely responsible for initial gains in strength resulting from a training program (early strength gains without seeing an increase in muscle size)
• Exercise induced adaptation - the training affect occurs through cell signalling pathways
• Synthesise new proteins - protein synthesis must exceed protein breakdown (over several weeks) for hypertrophy to occur with dietary protein necessary to promote process.