Exercise Physiology Flashcards
Varying Environmental Conditions
- Heat/Humidity
- Altitude
- Cold
Environment we compete in affects the way the body responds altering preparation and performance
Temperature Regulation
Core temp rises when heat gain exceeds heat loss which occurs when exercising, particularly in hot, humid conditions. The opposite occurs when heat loss exceeds heat production, as experienced in cold conditions.
Participation in the Heat
When the body exercises, it must maintain core temperature around 37 degrees Celsius. Heat is from environmental conditions and heat produced by active muscles.
Heat Loss Conduction (3)
- Heat exchanged by two objects in contact
- Rate determined by difference in temp, surface area (the greater the greater heat loss) and thermal conductivity of the object
- Athlete immersed in cold water or wearing an ice vest
Heat Loss Convection (6)
- Heat exchanged by contact with a fluid that is flowing
- Occurs when heat is carried away by air/water currents
- Layer of warm air surrounding body is displaced by cold air when air temp is lower than body temp
- Clothes minimise convection
- When air flow is slow, the air next to the skin acts as a layer of insulation and heat Loss is minimal
- When air flow is fast, heat loss increases as the zone of insulation is replaced
Heat Loss Radiation (2)
- Occurs when heat is transferred from a warmer body to the cooler surroundings without physical contact
- In the sun, people absorb radiant heat energy when surroundings are hotter than core temp
Heat Loss Evaporation (6)
- Cooling of the body as a result of vaporisation of sweat
- The muscles create heat and to avoid overheating the body uses blood to regulate temp
- Heat is transferred to the skin’s surface via the blood and is released as sweat
- Increased blood flow to skin occurs due to vasodilation of blood vessels
- Evaporation of sweat on skin creates cooling effect
- The cool skin cools the blood travelling to the surface
Heat Loss Evaporation Effects
- The higher the humidity the more ineffective evaporation becomes. Dry conditions are best.
- Rate of sweat is dependent upon: gender, number of sweat glands, body surface area, fitness level
- Excessive sweating leads to loss in body fluids and increases body temp
- Gradual dehydration leads to heatstroke
Rest in Heat
At rest in heat, heart rate and cardiac output increase (allows more blood to be sent to peripheries increasing radiative heat loss)
Double Heat Load (Resulting in Cardiovascular Drift)
Caused by heat from muscles and from the environment. Blood is needed to flow to muscles and vital organs to sustain energy and to the skin to maintain body core temp, impacting on performance. An increase in sweat rate causes a decrease in blood plasma volume.
Cardiovascular Drift
In an attempt to maintain cardiac output, heart rate increase. The increase in HR cannot keep up and cardiac output decreases. Skin blood flow decreases and oxygen to the muscles is decreased, placing strain on the body. Reduction in blood flow to working muscles increases the production of lactic acid. The reduction of blood flow to the skin reduces sweat rate inhibiting heat loss. These changes lead o a rise in body core temp and negatively affect performance.
Acclimatisation to Heat Program
- 5-10 days living/training in heat with sessions lasting 15-20 mins of light-moderate activity. Increase sessions to 45-60 mins for 8-9 days increasing in intensity. Complete 4-6 weeks prior to comp and 2 per week leading up to the comp. Can use artificial heat sources, climate chambers, saunas, sweat clothing.
Acclimatisation to Heat Benefits
- Sweat rate increases, start sweating at lower core temps (leads to lower core temps, skin temp and heart rate, allows more blood to be sent to working muscles)
- Sweat becomes more dilute and is distributed effectively keeping salt in the body (body uses greater surface area - better maintenance of core temp)
- Exercise with lower core/skin temp due to sweating adaptations (HR is lower, greater cardiac output to muscles)
Humidity
- Sweat evaporates more on dry days creating better cooling
- Humidity places stress on body as it limits the body’s ability to lose heat via Evaporation
- Eg. When 33 degrees Celsius and 100% humidity, actual temp feels like 55 degrees celcius
What to do When Exercising in the Cold
- Wear sensible clothes (allow for evaporation as damp clothing and wind chill increases heat loss)
- Cover extremities as they are areas of high heat loss and in cold experience peripheral vasoconstriction
Exercising in the Cold Causes
- Shivering: contractions of the muscles cause the body to increase in heat production
- Increase in sub maximal VO2 at given intensity (shivering can lead to glycogen depletion)
- Fine motor skills deteriorate ( reduced sensation in hands/feet due to vasoconstriction)
- Risk of dehydration (air must be warmed and humidified, reduced sensation of thirst)
- Hypothermia (when body temp blew 35 degrees Celsius)
Cold Acclimatisation
7-10 days prior to even (allows experimentation and psychological adaptation)
Altitude Effects
- Reduced air density (less friction) and gravitational pull benefitting throwers, sprinters and jumpers
- Lower oxygen affecting endurance performance
- Reduced barometric pressure causes reduction in pressure of oxygen entering the lungs (lower pressure of oxygen in alveoli meaning less transfers to blood during gaseous exchange)
Altitude Acclimatisation
- Expose through altitude houses/tents, altitude masks, living at high altitude and training under normal conditions
- Live high, train low
Altitude Acute Adaptations
- Increase in pulmonary ventilation (increased respiratory Rate to increase oxygen getting to muscles)
- Increase in HR during rest and sub maximal exercise to increase oxygen to the muscles
- Decrease in plasma volume to increase concentration of haemoglobin in the blood
Altitude Chronic Adaptations
- Increase in Haematocrit (increase in RBC causing increase in haemoglobin concentration)
- Increase in Mitochondria, Aerobic enzymes, capillaries, myoglobin
- Increase in DPG
Oxygen requirements for ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- No
- No
- Yes
Speed of Energy Supply for ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- Very Fast
- Fast
- Slow
Fuel Source for ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- Creatine Phosphate
- Carbohydrates
- Carbohydrates, Fats and Protein
Amount of ATP Production for ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- Limited
- Limited
- Unlimited
By Products of ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- None
- Lactic Acid
- CO2, H2O, Heat
Duration of ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- 0-10 secs
- Up to 1 min
- Forever
Cause of Fatigue for ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- Limited Supply of ATP/PC
- Lactic Acid Production
- Unlimited
Activities used for by ATP/PC, Anaerobic Glycolysis (Lactic Acid) and Aerobic Energy Systems
- Power Based Activities
- Sprint Endurance
- Long Duration
Fuel Sources Affected by Intensity and Duration
Main energy source for sub-maximal exercise are stored fats. As intensity increases glycogen contributed. Athletes hit the wall when muscle glycogen runs out. Stored liver glycogen kicks in. Depletion of liver glycogen affects decision making ability. Fats then become main source and intensity is reduced as fats are more difficult to break down. Depletion of fats results in protein as main energy source (endurance events).
Training Types (8)
- Continuous
- Cross-training
- Fartlek: continuous training in which the intensity is varied
- Interval: bouts of high intensity with rests in between
- Resistance: forms of resistance that overload the muscles
- Circuit
- Flexibility: Maintain or improve the range of motion around a joint
- Plyometrics: resistance training using the weight of the body to apply overload in dynamic activities