Most aerobic and strength training programs inherently cause muscles to contract and flex, but stretching does more than get the blood flowing:

• Increases flexibility
• Improves range of motion
• Improves circulation, which can lead to quicker recovery 
• Can relieve stress and relax muscles
• Can help prevent and mend injuries

Passive Stretching
Stretching in which our weight or an object is used to stretch beyond natural range of motion

• Should be done at the end of a workout
• Hold between 15 and 30 seconds

This type of stretching is the most commonly practiced and universally known. While passive stretching does have value, new research shows that passive stretching can increase the risk of injury if performed before a workout.

According to research by the American Journal of Applied Physiology and the American College of Sports Medicine, passive stretching can decrease strength and muscular power output by up to 20% and potentially tear your soft tissue, limiting the amount of muscle available for recruitment. 

It can also hinder the nervous system's communication with the involved muscles and make them looser, weaker and less stable for an hour or more after stretching.  Due to hindered communication between the brain and the nerves in the muscle, passive stretching also decreases blood flow and can create muscle imbalance by stretching one muscle more than it's counterpart. 

Suggested Passive Stretches

• Upper Trapezius: Place left hand on head and position right arm behind back, pull head toward shoulder
• Calves: Position body in front of a wall and lean forward to stretch
• Pectorals: Place arm against a door frame or wall, then gently push shoulder forward
• Hamstrings: Place foot on a sturdy box or bench, then lean forward from the hips until feel a stretch

Active or Dynamic Stretching:
This method of stretching uses only opposing muscle groups and encourages a more natural stretch. By contracting an opposing muscle group the group being stretched experiences a natural stretch similar to that it will receive in the workout.

• Best for pre-workout routines
• Do 4-6 bodyweight exercises at a slow pace and limited range of motion
• Cycle through each exercise again slightly faster and with a wider range of motion
• Actively hold each position for 10 to 15 seconds

The "stretch" positions can be very similar to passive stretches, but they are being held using muscular effort, not outside force.

Suggested Active Stretches

• Lats: Reaching arms straight overhead
• Chest: Extend arms out to the sides, and retract shoulder blades
• Quadriceps: Flex heal toward butt, contracting the hamstrings
• Hamstrings: Extend leg straight in front, and contract the quads

Stretching Tips

• Target major muscle groups like the calves, thighs, hips, lower back, neck and shoulders
• Make sure to stretch the muscles or joints you use the most in your workouts
• Get warm; muscles are like rubber bands. Warm ones stretch. Cold ones snap
• Pace yourself
• Hold for about 30 seconds
• Don't bounce, it could lead to torn muscles
• Relax and breathe freely.