Exercise physiology

Heat - Conduction

• Heat exchanged by 2 objects in contact

• Factors:

  • Temp differences, and SA

Heat - Convection

• Heat exchange by contact with a fluid that is flowing

• Occurs when heat is carried away from the body by air or water currents

Heat - Radiation

• Occurs when heat is transferred from a warmer body to the cooler surroundings without physical contact

• When exposed to sunshine

Heat - Evaporation

• Is the cooling of the body as a result of the vaporization of sweat

Heat - Dehydration

• occurs when the amount of water leaving body is greater than the amount

Cardiovascular drift

• When heart rate increases to maintain cardiac output caused by a decrease in stroke volume

Physiological Changes - Heat

• When exercising in heat, body directs blood flow to the skin and away from the working muscles to increase heat loss via evaporation

• As ^ sweat rate → decreased blood plasma volume

• As a result cardiovascular drift occurs

• Decreased blood flow to working muscles increases lactic acid production

• Reducing blood flow to skin, decreases sweat rate, therefore can’t lose heat to evaporation, increasing core body temp, and negatively affecting performance.

Immediate changes to heat

1. Heat exhaustion = ineffective circulatory system + dehydration

   • Dehydration because of exercising in the heat

2. Heat stroke = severe dehydration

   • Excessive sweating will affect the body in its ability to lose heat and maintain performance levels

Heat related injuries

• Progressive and they appear in a particular order

1. Stage 1:

   • Dehydration occurs when fluid replacement does not match fluid loss

2. Stage 2:

   • Heat exhaustion occurs when the dehydrated athlete continues to sweat, thereby losing more fluid. If they fail to replace lost fluid, they risk stage - 3 heat stroke

3. Stage 3:

   • Heat stroke occurs when the body stops sweating, resulting in the rise of the core temp to dangerous levels caused by a lack of evaporative cooling.

Heat Stress Steps

1. At rest in hear, conduction, convection and radiation become methods of heat gain.

   • As a result, HR and SV ^ to allow the body to send more blood to the skin, creating cooling

2. Commence exercising - HR and SV continue to rise as the body must also send blood to the working muscles

3. Whilst exercising, core body ^ placing extra strain on body’s cooling mechanism. Hotter = more dependent on evaporation

4. A hot ambient and core temp = a double heat load

5. PLayers drink fluid to remain hydrated

6. As exercise continues, player continues to drink, however fluid loss is higher = dehydration

7. Dehydration results in loss of plasma volume. Affects the amount of blood which can be delivered

8. As blood volume v, the body must try and maintain cardiac output to ensure enough blood is being sent

   • HR ^, however this increase is not as significant as the v in SV. Therefore cardiac output v = less blood to muscles

9. Leads to reduced performance and an ^ core body temp, headaches, dizzy, nausea

10. Continued exercise = severe dehydration

11. With decreased CO, body must decide:

    • Send blood to working muscles and organs

    • Send blood to skin for cooling

12. The body chooses vital oragns, leading to recued heat loss via evaporation. Therefore core temp ^ placing athlete at extreme risk of unconsciousness, coma or death.

Fluid replacement strategies to prevent dehydration - Pre exercise

• Involves increasing body’s fluid stores by consuming extra fluid before an event

• 1L before exercise recommended

  • 600mL 3-4hrs beforehand

  • 400mL just before game

  • Avoid caffeine

Fluid replacement strategies to prevent dehydration - During exercise

• Drink approx 200mL every 15 mins during activity = influenced by environment + activity

• Don’t just drink when thirsty

• Avoid drinking just water as salt lost in sweat needs replacing

Fluid replacement strategies to prevent dehydration - Post exercise

• The goal is to replenish back to pre exercise weight

• Every 1L of sweat loss, consumer 1.5L of water

• Consumer slightly salty liquid

Hyponatremia

• An abnormally low concentration of sodium (electrolytes) in the blood

• When a person sweats profusely for extended period, drinking too much water can cause problems in the body as water and salt is lost nad only salt is replaced.

• Imbalance can affect brain

Heat Acclimatisation

• When heat tolerance is improved by repeated exposure to hot environments.

Heat Acclimatisation - How to acclimatize

How long:

• The first session should last for 15-20 mins and be combined with light to moderate activity

• SHould increase to 45-60 mins daily for approx 8-9 days with increased intensity and duration

• 5-10 days of living and training and heat is recommended.

Where:

• Athletes who are unable to use natural acclimatization should use

• Artificial heat sources

  • Climate chambers, saunas, sweat clothing

When:

• Should be completed 4-6 weeks before competition and then 2 per week leading up to competition to maintain benefits

Heat Acclimatisation - Major adaptations

1. Sweating:

   • Increased blood plasma volume, therefore more blood leading to increased length of time until dehydration

   • Increased sweat rate

   • Start sweating at a lower core body temperature, leads to more blood being sent to working muscles

   • Sweat becomes more dilute and distributed over body more effectively, keeping salt in the body

2. Cardiovascular:

   • Heat acclimatised athletes exercise with lower core and skin temp due to sweating adaptation

   • As a result, HR is lower than average due to more efficient cooling system

   • A lower core temp also reduces body’s need to send blood to the skin for cooling, therefore greater % of Q going to active muscles

   • Increased blood volume to allow for increased sweating

Heat Acclimatisation - Strategies to manage performance in heat

1. Hydration:

   • Hyper hydrate by consuming 300 - 400ml just prior and 600ml 3-4 hours before

   • Consume approx 150-200 ml every 15 mins during exercise

   • Consume 1.5x weight loss after

2. Clothing:

   • Wear loose fitting, light coloured clothing to permit free air circulation between skin and environment, promoting convection and evaporation

3. Pre cool body:

   • Includes, ice - towel, immersion in water, slushies

4. Acclimatize:

   • See heat acclimatization

5. Protection from sun

   • Reduce length of warmup

   • Utilise shade

Humidity

• Defined as the amount of water vapor that exists in the air

• It will:

  • Increase sweat rate

  • Increase fluid loss

  • Decrease the effectiveness of cooling via evaporation

  • Decreases performance, particularly aerobic

Heat index

• Used to determine how hot it feels by considering the air temp and relative humidity

Physiological Responses - Cold

1. Peripheral vasoconstriction

   • Involves the redirection of blood flow, away from the skin’s surface and towards the body’s core, to minimize heat transfer from the blood to the cold external environment

2. Shivering

   • Involuntary muscular contraction is designed to help increase heat production

3. Piloerection

   • When the hairs on the body stand on end and trap a warm layer of air close to the skin to help keep the skin surface warm

Performance in cold weather

• Increased submaximal VO2 at a given intensity

  • For endurance athletes, shivering may lead to early glycogen depletion

• Fine motor skills detireorate

Performance in cold weather - Wind chill

• Apparent temperature felt on skin due to combination of wind + ambient temp

• Wind and increased heat loss via convection by constantly removing warm layer

Performance in cold weather - Risk of dehydration

• Inhaled air is very dry and cold

  • Needs to be warmed and humidified therefore increases fluid loss

Performance in cold weather - Hypothermia risk

• If the body becomes too close and heat needs to be retaines, blood flow to the skin is restricted

• Blood vessels will vasoconstrict to decreases blood flow to the skin, thereby decreasing heat loss

• The body also responds by initiation small, involuntary body muscular contractions - shivering - to increase body temp

• Piloerection also occurs

Cold acclimatisation

• Less critical than in heat

• should occur 7-10 days before

  • Allows experimentation

  • Physiological adaptation

Strategies to help cope with exercising in the cold

1. Experiment with the length of warm up

2. Experiment with layered clothing

3. Psychological acclimatisation

4. Ensure adequate fluid replacement, as water loss with be increases via the need to humidify dry, cold air before it enters the lungs

• Body’s extremities are all areas of high heat loss experiencing peripheral vasoconstriction

• Athletes will use more glycogen and fats due to shivering using them as a fuel source. This will have a negative impact on performance as glycogen stores will deplete earlier on in the event

• Cold environments can cause dehydration as the body moistens the air we inhale, losing fluid from the body

• Cold weather increases the chances of injury, if not adequately warmed up

Altitude

• Air at any levels:

  • 20.93% Oxygen

  • 79.04% Nitrogen

  • 0.03% CO2

• The more air above this point, the greater the barometric pressure

  • At sea level BP = 760mmHg

  • At Mexico city, 2240m above, BP = 585mmHg

  • Mount everest, 8848m above, BP = 231mmHg

• At altitude, there is a reduction in the pressire of O2 entering the lungs. Reduces the pressure differential between the alveoli and the capillaries, resulting in less O2 diffusing from the alveoli

Altitude - High

• Less air pressure

• Low pressure differential between alveoli and capillaries

• Harder to breathe as the pressure difference between the alveoli and capillaries is low

Altitude - Low

• High air pressure

• High pressure differential between alveoli and capillaries

• Easier to breathe as aire moves from high pressure in the environment to low pressure in the lungs

Altitude Physiological responses - Acute

• Increased respiratory rate

• Increased tidal volume

• Increased nausea, headaches

• Increased HR + cardiac output at rest

• Decreased plasma volume

Altitude Physiological responses - Chronic

• Increased haematocrit

• Increased mitochondria

• Increased aerobic enzymes

• Increased capillaries

• Increased myoglobin

Impact on performance - Altitude

Positive impacts: Power athletes

• Less drag due to thinner air causing less resistance

• Decreased gravity effect on objects ie. Objects travel further

Negative impacts: Endurance athletes

• Less O2 uptake and decreased pulmonary diffusion meaning reduced ability of body to provide O2 to the muscles

• Therefore aerobic metabolism is affected

• Decreased humidity at altitude means an increased dehydration risk

Altitude acclimatisation

• Describes the improved physiological response to altitude hypoxia

Method 1: Live high, train low

• Involves daily intermittent exposure to artificial environments whilst maintaining normal training intensities

• Can use hypoxic apartments, houses and tents

• More beneficial as it allows players to maintain training intensity

Method 2: Live high, train high

• Athletes who live at altitude to achieve the physiological benefits of a decrease in O2 concentration and train at altitude to obtain adaptations

• Usually requires going to at least 2000-3000m above sea level for 3 - 4 weeks reduced training intensity over period - detraining

• Best for teams who compete at altitude

Method 3: Live low, train high

• Athletes live at sea level but train in hyperbaric chambers or altitude tents to simulate a hypoxic environment

• No evidence supporting chronic adaptations from this method

Energy Source

• Refers to which energy system used to produce ATP

  1. ATP/PC

  2. Lactic Acid

  3. Aerobic anergy

Fuel Source

• Refers to whats required to fuel the exercise

  1. Carbohydrates - MN

  2. Fats - MN

  3. Proteins - MN

  4. Creatine Phosphate

Fats

• Fats are broken down into either fatty acid (FFA), which are found in adipose tissue and the blood, or triglycerides, stored in muscles.

• Represent the body’s most plentiful source of potential energy. Primary fuel source at rest + prolonged submaximal

• Trained athletes can use glycogen sparing

Glycogen Sparing

Glycogen sparing is the body’s ability to conserve stored carbohydrates (glycogen) by shifting to burn more fat for energy during endurance exercise

Protein

• Protein make 5-10% in ultra endurance events energy contribution

• Essential nutrient needed to:

  • Build tissue + cells

  • Act as an enzyme

  • Production of red blood cells

• Stored in muscles and around the body

• Mainly used for growth and repair

Carbohydrates

• Broken down into glucose for blood transportation

• Excess blood glucose converted to glycogen and stored in muscles + liver

• When muscle + liver glycogen full, remaining is stored in adipose tissue

• Carbs are preferred source, especially during exercise

Glycaemic Index

• Ranking of Carbs based on immediate effect on blood glucose levels

• Scale 1 - 100

  • Low = Apples, beans

  • Moderate = Corn, pasta, potato

  • High = White rice, white bread, honey

High GI

• Breakdown quickly during digestion - therefore have an immediate effect on increasing blood sugar levels

• When to consume?

  • Immediately before

  • During exercise

  • Immediately after

Low GI

• Breakdown slowly during digestion, resulting in a slow release of glucose into the bloodstream

• Best consumed in pre event meal and after event

  • Pre event meal (1-4hrs)

  • After exercise (1-2hrs)

Rebound hypoglycemia

• Consuming High GI foods 30 - 120 mins before may cause rebound hypoglycemia

• Immediate after consuming CHO, there is a rise in blood sugar, therefore insulin released

Pre competition - Leading up to the event

• Carbohydrate loading is a nutritional intervention aimed at delaying the depletion of glycogen stores. Increases CHO consumed prior with the aim of storing extra glycogen in livers + muscles

• Pre event is needed to increase glycogen

• Ensures hydration

• Keeps internal track confortable

• Consumed 1 - 4hrs before

• 600 - 800ml in fluid 1 hr priod

Carb loading - Three day

• Consume approx 7 - 8g/kg body weight of CHO for three days leading up

• Can still exercise however significant tapering occurring leading up to comp

• Not suitable for sports which happen each week

Carb loading - One day

• Consume approx 8 - 10g/kg body weight of CHO the day before

• Must taper

During Competition

• Consumption of CHO prevents low blood sugar levels in sports lasting up to 60 mins

• Consume 30-60g of high GI CHO per hour or 1g/kg body mass every hour

• Consume approx 150 - 200 ml of water every 15 mins to prevent dehydration

• Electrolyte drinks can be drunk

• Avoid high fibre

Post Competition - First 30 mins

• After 30 mins, muscles are most responsive to topping up

• 1g/kg of body mass of high GI CHO within 30mins of the event

• Increase due to consumption of High GI

Post Competition - Next 24hrs

• Takes at least 24 hrs for glycogen replenishment after heavy endurance work

• At least 7-10g/kg of body mass of low to moderate GI CHO over the next 24 hrs

• Protein consumption

• Fluid which equates to 1.5x weight loss

Fluid replacement strategies to minimize dehydration - Pre comp

• 1L total beforehand

  • 600ml 3-4hrs prior

  • 400ml just before to prime stomach

• Avoid caffeine = diruetic

Fluid replacement strategies to minimize dehydration - During comp

• 200ml every 15 mins

• Don’t drink just when thirsty

• Drink sports drinks

Fluid replacement strategies to minimize dehydration - Post comp

• Replenish back to pre exercise weight

• For every 1L of sweat lost, consume 1.5L

• Slight salty liquid

Legal Performance Enhancers - Protein Powder

• How consumed:

  • Powders are convenient post - training

  • 790 mins also need CHO

• Physiological benefit:

  • Can increase muscle growth + tissue repair

  • Protein as a fuel source

  • Improve recovery rate from training

  • Increase muscle mass only if athlete is resistance training

• Risks:

  • Not really any - just moderation

  • Colon cancer, kidney damage

• Athletes who benefit:

  • Sports people wanting to increase muscle bulk (body builder)

  • Athletes in heavy training

Legal Performance Enhancers - Caffeine

• How consumed:

  • Tea, coffee, choc, other drinks

  • Guarana = double the amount

• Physiological benefit:

  • Acts as analgesic, reducing perception of effort, therefore increases time to exhaustion

  • Stimulates CNS, increasing alertness and arousal levels and decreasing reaction time

  • Thought to increase glycogen sparing through oxidation of fatty acids

  • Removed from WADA in 2004

• Risks/Side effects:

  • Potent diuretic

  • Increases heart rate

  • Irritability

  • Muscle shakes

  • Insomnia

  • Over arousal

• Athletes who benefit:

  • Endurance events 90mins +

  • SHort duration, increasing intensity

  • Events with fast reaction time

Legal Performance Enhancers - Creatine

• How consumed:

  • Meat and fish → amino acids

  • Creatine monohydrate

• Performance benefit:

  • Used to improve muscular power and reduce muscle damage

  • Provide increased CP in the muscles, therefore decreases dependence on anaerobic Glycolysis system, therefore ^ ATP

  • Stimulate protein synthesis

  • Improve buffering effect on ADP = ^ supply of ATP

• Physiological risk/Side effects:

  • Weight gain

  • Cramping

  • Diarrhoea

  • Dehydration

• Athletes who benefit:

  • Short duration

  • High intensity explosive power activity

    • Eg. Weight lifting

Illegal Performance Enhancers - Anabolic Steroids

• How consumed:

  • Orally, injected intramuscularly/gels/creams

  • Synthetically produced drugs

• Physiological benefits:

  • ^ Performers size, strength and power

  • Decreased recovery time

  • Stimulates protein synthesis

  • Improved rate of tissue repair

• Physiological risk:

  • Acne

  • Depression

  • Liver cancer

  • Aggression

• Athletes who benefit:

  • Sports requiring strength and power

Illegal Performance Enhancers - Blood doping: Blood transfusion

• How is it consumed:

  • Infusing extra human blood into athlete via transfusions of their own blood

  • Look at steps briefly

• Physiological benefits:

  • Increased red blood cell number

  • Allows for more oxygen to be delivered to the muscle

  • Improve aerobic capacity and VO2 max

  • Better aerobic performance

• Physiological risk:

  • Increase risk of infection

  • Increase blood viscosity

• Athletes who benefit:

  • Endurance athletes

Illegal Performance Enhancers - Blood doping: Erythropoietin (EPO)

• How consumed:

  • Injection

• Physiological benefits:

  • Increased red blood cell number

  • Allows for more oxygen to be delivered to the muscle

  • Improve aerobic capacity and VO2 max

  • Better aerobic performance

• Physiological risks:

  • Increased viscosity

  • Heart attack

  • Blood clots

  • Stroke + dehydration

• Athletes who benefit:

  • Endurance athletes

Illegal Performance Enhancers - Blood doping: Synthetic Oxygen Carriers

• How is it consumed:

  • Injecting purified proteins or chemicals

• Physiological benefits:

  • Increased red blood cell number

  • Allows for more oxygen to be delivered to the muscle

  • Improve aerobic capacity and VO2 max

  • Better aerobic performance

• Physiological risks:

  • Increased blood viscosity

  • Contracting disease

• Athletes who benefit:

  • Endurance athletes

Periodisation

• The planning, well in advance, of training variables to achieve optimal performance at the most crucial times

• Involves varying the volume and intensity of training

  • Prevents overtraining + burnout

  • Promote enthusiasm

  • Minimizes injury likelihood

  • Plans for athletes to peak at the right time

• Macrocycle = whole year

• Several mesocycles make up a macrocycle

• Several microcycles make up mesocycle

Phases of training

1. Preparation

   1. General

   2. Specific

2. Competition

   1. Pre - comp

   2. Comp

3. Transition phase

Preparation phase - General

• Objective: Training is designed to build a suitable aerobic base and skill level leading into the competition

• High volume training with low/medium levels of intensity

  • Continuous, interval and fartlek training

  • Flexibility training

  • Basic skill work

• Fitness testing is used to gather baseline data and compare it to other players, teams, previous seasons, etc.

Preparation phase - Specific

• Objective: Develop game specific fitness, skills and strategies

• Training may need to be personalised depending on players/positional needs

• Reduced training volume with increased intensity occurs during this macrocyle

  • High intensity interval training

  • Weight training

  • Plyometrics training (up to 2x per week)

  • Flexibility/agility training

• Appropriate mental skills developed

Competition phase - Pre competition

• Objective: To reach peak match condition

• Focus on training moves to match specific intensities, durations and tactics

• Application of the principle of specificity is crucial

• Continue to develop appropriate mental skills

• Intensity of training increases

• Volume of training decreases

• Recovery between sessions is essential

• Play trial games

Competition phase - Competition

• Objective: Fitness is maintained - dependent on individual situations (injury, illness, position, no. of games played, game time)

• Players at optimal levels of skills and fitness

• Focus on psychological and tactical preparation

• Recovery sessions are critical, particularly after games when players are often sore

• Constant peaking and tapering are critical in allowing sufficient recovery during the season

• Variation in the hard/easy cycles forms a “training wave” and is of particular significance where fixtures are played weekly to ensure players are optimally prepared for competition

Transition phase

• Training volume and intensity are significantly reduced to allow for full physical and psychological recovery

  • Older players find this time crucial in allowing the body to recover

• Aerobic fitness should be maintained to avoid detraining through involvement in enjoyable activities

  • Surfing

  • Different sports

• Monitor nutrition to ensure a return to active participation close to playing weight

• Opportunity for corrective surgery and rehabilitation

• Specialised programs to correct structural or skill deficiencies

Tapering

• Involves decreasing the volume of training whilst maintaining or increasing intensity an athlete dows to allow the body time to recover from the stresses placed on them during training

• Normally done after a block of hard training leading into a major competition

• Normally between 4-28 days depending on type of event being tapered for

• Endurance athletes = short tapers

• Strength athletes = longer tapers

Tapering - Physically

• Should be long enough to repair tissue damaged during training and refuelling energy stores

Tapering - Mentally

• Help the athlete reach their Ideal Performance State (IPS)

Strategies used to taper

1. Reduce training volume and maintain or increase training intensity to a level greater than or equal to comp activity

2. Increases use of recovery techniques between sessions to improve the quality of recovery

3. Monstering diet to ensure adequate glycogen stores

4. Individualize the program to ensure needs are met

Peaking

Term used to describe a temporary training state which allows the athlete to perform at their optimal level

Recovery

Recovery strategies are designed to reverse the impacts of fatigue and return the athlete to performance readiness both mentally and physically

• Nutritional recovery and strategies:

  • Hydration

  • Food/fuel

• Physical recovery strategies:

  • Sleep/rest

  • Cool down

  • Massage

  • Psychological - relaxation

Fitness maintenance

• Fitness levels are sustained but not developed or overlooked

  • Cannot continuously overload because needs time to recover

  • During competition phase maintenance phase takes place

  • During season maintain fitness levels + ^ increase

Overtraining

• Occurs when an athlete has been repeatedly stressed by training to the point where the rest periods between sessions are no longer adequate for recovery to occur

• As a result, training no longer leads to performance improvement

Common causes of overtraining

• Workload too high

• Lack of variety in training sessions leading to staleness

• Insufficient recovery from illness

Preventing overtraining

• Well planned training programme incorporates regular rest

• Individualise training programmes

• Educate players and coaches on the signs of symptoms and overtraining