SHORT-TERM or ACUTE PHYSIOLOGICAL RESPONSES TO EXERCISE:
Body Temperature h (Increase)
§ Working muscles produce heat
§ Harder and faster = more heat.
§ Blood transports heat to all parts of the body = warm-up
§ Body quickly heats up and will overheat – response is to send blood to skin surface for cooling and to produce sweat.
§ Moisture on the skin cools the body quickly (25x faster than air).
§ (This why when you get out of the water at the beach or pool – you get cold quickly).
§ This enables us to exercise and perform for longer.
§ Sweat works just like the radiator in a car engine –
circulating water keeps the engine cooler and prevents overheating.
Lactic Acid h (Increase)
§ Working muscles produce Lactic Acid
harder and faster = more Lactic Acid
§ Lactic Acid is cleared by the blood. (plasma)
§ Lactic Acid is delivered to the Liver
Cori Cycle – Q converts Lactic Acid into glucose which re-enters the blood stream – this is a slow process.
§ During hard exercise blood cannot clear the Lactic Acid fast enough.
§ There is a build-up of Lactic Acid – this causes muscle fatigue and we have to slow down or stop.
Heart Rate h (Increase)
§ Lactic Acid in the blood – Heart beats faster to speed up blood flow to start removing lactic acid.
§ Working Muscles also require Oxygen and Glucose. By speeding up the blood flow more O2 and glucose (carried in the blood) can be delivered to the working muscles which helps produce energy.
§ Working Muscles also produce Carbon-dioxide and water. These must be cleared away from the muscle by the blood. Faster blood flow allows faster removal of water and CO2.
§ HR remains high after we stop exercising – blood clearing the Lactic Acid, CO2 & water.
Breathing Rate h & Tidal Volume h (Increase)
§ Working Muscles require Oxygen to help produce energy.
§ Speeding up the Breathing Rate more O2 can be absorbed by the blood and delivered to the working muscles.
§ Taking deeper breaths (Tidal Volume) allows more air to flow into the lungs, therefore more O2 can be absorbed by the blood.
§ Working Muscles also produce Carbon-dioxide and water. These must be cleared away from the muscle by the blood to the Lungs.
§ Increased breathing Rate & Tidal Volume allows us to exhale water and CO2 faster.
§ Breathing Rate remains high after we stop to clear CO2.
LONG-TERM or CHRONIC PHYSIOLOGICAL RESPONSES TO EXERCISE:
§ Cardiac hypertrophy (or heart increases in size). Chambers of the heart increase in size (particularly left ventricle) –in endurance athletes (e.g. distance swimmers and runners) and an increase in thickness of the ventricular wall in non-endurance athletes (e.g.wrestlers, shot-putters)
§ Increased stroke volume- as heart develops larger chambers, thicker walls and improved extensibility and contractility, it pumps a greater volume of blood with each beat. The body has improved biomechanical efficiency. Blood flow to working muscles also decreases, becauses the muscles are able to extract increased amounts of oxygen from the blood.
§ Decreased resting heart rate- since cardiac output required at rest is constant, increases in stroke volume are accompanied by corresponding decreases in heart rate. There is an improved, more efficient delivery of oxygen to the working muscles which in turn improves performance. The heart has less work to do and is more efficient at taking in oxygen and transporting it around the body.
§ Increased blood volume –training stimulates increased plasma and red blood cell volumes, thus improving the effectiveness of oxygen delivery and waste removal
§ Lower blood pressure
§ Increase in lung volume –increased tidal volume, breathing frequency, diffusion capacity (at the alveoli)
§ Changes in body composition –decreased total body fat and often weight as increased energy consumption burns excess calories.
§ Muscle hypertrophy (growth in size of muscle) because of an increased number and size of myofibrils per fibre, increased amounts of myosin and actin and increased fibres size and (possible) number
§ Increased capillary density per fibre which allows more efficient oxygen delivery to muscles
§ Increased strength and amounts of connective tissue, including tendons and ligaments
§ with flexibility training – increased resting length of muscles, tendons and ligaments, increased joint range of movement, decreased resistance to joint movement.
§ Improved recovery from high-intensity bouts of exercise so heart rate returns to normal faster and exercise heart rate is also lower
§ Improved ability of muscles to store energy (glycogen) and therefore won’t get tired so quickly when exercising
-all of these occur as increased and regular training occurs, as the muscles can take more oxygen from the blood vessels and become better at using oxygen to produce energy.