2 1. Your Heart Beats Stronger and Faster. (Why ?) During exercise adrenaline causes the heart beat to increase.This is caused by an increase demand for oxygen in muscles.Heart rate at rest, during exercise and during recovery can tell us a lot about a persons fitness (what ?).
3 2. Your Breathing Quickens and Deepens The demand for oxygen increases with exercise and more oxygen must be breathed in to allow the blood to transfer it to the working muscles.The efficiency of your breathing depends on how much air we can take into the lungs.The most important structures are the alveoli (tiny air sacs).Training can increase the capacity of the lungs which equals More O2, less Co2 and increased Vo 2 max.
4 3. Your Body Temperature Increases (What Problems Might This Cause Sportsmen ?) When muscles work they generate heat, so body temperature rises.Normal body temp. is 37oc.Body temp must be regulated by heat radiating to the skin (redness of skin) and water evaporating by sweating.When we shiver our muscles work to produce heat
5 4. You Start To SweatHeat from the muscles causes temperature to rise.The body gets rid of this heat through sweating.Sweat comes out of the pores of the skin.However when we sweat we lose salt and water as well as heat and this can cause problems.
8 5. Lactic Acid Builds Up in the Muscles 5. Lactic Acid Builds Up in the Muscles. (particularly during anaerobic high intensity work)Lactic acid is a waste product of energy production.As the muscles use energy, lactic acid builds up.Lactic acid is a poison that causes the muscles to ache and eventually stop working.During light aerobic exercise lactic acid builds up more slowly because there is enough oxygen in the blood to neutralise the acid.