You have decided that you are ready to start a fitness program. you have not exercised on a regular basis in about a year. what principles of exercise should you consider when starting a new exercise regime and what should you do before and after every workout to minimize injuries. < < read less

Before: warm up, slowly increasing heart rate and warming up muscles. 
After: cool down, slowly decreasing heart rate, removing lactic acid, and reducing the current level of elasticity in the muscles.

Principles of Training:
Progression: so that the athlete does not overload their muscles immediately
Overload: in the sense that the athlete overloads their muscles for their current fitness level. eg. if can run 2km, aim to run 2.5km in the same time.
Rest: rest is important to let the minute muscle tears recover for the next training session
Time: train for approx. 45-60 minutes to improve fitness
Frequency: 3-5 times a week to improve fitness
Tedium: have fun during the training sessions, so that athlete does not get bored