Immediate Physiological Response to Training - (Excellent information at HSC Online & 

Heart rate - refers to the number of times the heart beats per minute.

1. When exercising, heart rate increases quickly once beginning exercise and then plateaus once a constant effort is maintained. Heart rate may also increase before exercise actually commences in anticipation of the exercise as shown in the graph below.

2.It will increase or decrease from this plateau if the intensity of the exercise is variable (eg: sprinting then jogging then sprinting again).

3. Once the athlete stops exercising heart rate will decrease steadily as the body replenishes oxygen supplies and removes waste products. The length of time it takes for the heart rate to return to normal will depend on the intensity and length of the exercise and the fitness of the athlete. (A fitter athlete is better able to replenish oxygen and remove waste products so heart rate will return to normal faster than an untrained athlete).

Graph from - HSC online - PDHPE - Factors affecting performance

Stroke volume - refers to the amount of blood pumped from the heart in one contraction. This is measured in millilitres and is the blood pumped from the left ventricle. During exercise stroke volume increases as the heart pumps more forcefully to try and get more blood around the body. The force of the contraction generally increases inline with the heart rate of the individual until a threshold point is reached and the heart is pumping as hard as it can. This threshold will occur before maximum heart rate is reached. (See graph below from HSC Online).

Cardiac output - refers to the amount of blood pumped from the heart in 1 minute. During exercise cardiac output increases to supply the muscles with oxygen and remove waste products.

Lactate levels - refers to the amount of lactic acid in the bloodstream. During exercise lactate levels will increase as the body produces lactic acid in creating energy for the muscles.  The amount will vary depending on the intensity of the exercise. (High intensity exercise will mean higher lactate levels.

Ventilation rate - refers to the total volume of air taken into the lungs per minute. This is affected by 2 factors.

1. The number of breaths taken per minute.

2. The depth of each breath.

During exercise both of these variables will increase and as a result the total volume of air inhaled into the lungs per minute increase also.