Piriformis Stretch

This pose is wonderful for stretching the muscles of the hips, thighs and buttocks.
Start this posture seated on your sit bones with your legs straight out in front of you.

• bend the right knee and place the foot on the floor
• take the right outside ankle to the left thigh just above, not on, the left knee
• reach behind you and place your hands on the floor
• sitting tall, slowly begin to bend the left leg until you feel a good stretch in the right leg and hip
• press the right knee away from the body to help make a straight line between the knee and foot
• only bend the left leg to a comfortable extent, never over stretch or over strain
• try to maintain a tall spine with the chest lifted
• hold for between five and ten breaths before slowly straightening the left leg and moving the right leg back to the floor so both legs are straight
• repeat the above with the left leg

photo courtesy of Yoga Journal

Navasana - Boat Pose

This very effective pose strengthens abdominals and quads as well as working the back and chest muscles.
Start from seated making sure you are on your sit bones and your legs are straight in front and just a little apart. Next:

• bend both knees and put your feet to the floor
• place your hands behind your thighs near the back of the knees and keeping the spine straight start to adjust your weight until you are balanced on your bottom
• lift the feet until your shins are level with the floor, and make a straight line between knees and feet, do not allow the feet to move inward or the knees to drop out
• flex the feet and ensure your chest is lifted to maintain a long spine
• release the hands from behind the knees, straighten your arms with the fingers pointing towards the feet with the arms parallel to the floor
• maintain the leg lift and hold for between five and ten full breaths
• to release the pose place your hands behind the thighs near the backs of the knees and bending the knees take the feet to the floor as you adjust your weight forwards
• straighten the legs and relax for a few moments

photo courtesy of Yoga Journal  

Perfect Quad Stretch

It's more usual to stretch the quads while standing. This is perfectly acceptable but more often than not when I watch people stretch in this way they are doing it incorrectly and not really benefiting from the movement. A foolproof way of quad stretching is by lying on the floor.

• begin by lying prone in a straight line, make sure both hip bones can be evenly felt against the floor
• place your forehead to the floor or if this is uncomfortable put your left hand under your forehead and rest your head on the hand
• press your pubic bone into the floor, 'tipping' the pelvis and lengthening your spine, maintain this position throughout the stretch
• bend your right knee and reach behind to grasp the foot or ankle with the right hand, try not to lift the chest and shoulders off the floor
• on an out breath, ease the foot closer to the buttocks while maintaining both hip bones on the floor and the pubic bone pressed into the floor
• try to ease the foot closer to the buttocks on each out breath, do this for five breaths before releasing the foot to the floor
• rest for two breaths then repeat using the other leg and hand

Often when I teach this in class students find it more difficult and they achieve a greater stretch than if they use the standing version.

Hamstring and Spinal Stretch

This is an intense stretch of the hamstrings and back. Only go as far as you can when stretching, never over-stretch or over-strain. Yoga is not a competition and if you don't take care and approach each stretch with concentration, attention and without ego you can injure yourself. Whether you are in a class or practising at home alone you should approach each asana (posture) in the same way: as well as you can on any given day. Some days you'll have better stretching days than others, in the same way you have better running or cycling sessions.
Begin by standing with the feet parallel and just a little apart near the back of your practise mat:

• imagine you are standing on a clock. Turn the right foot so the toes point at 1 o'clock then take a large step forwards with your left leg keeping the left foot at 12 o'clock
• align your hips straight ahead
• inhale and raise both arms above your head
• exhale and bend forwards from the waist, keep the chest and head lifted looking ahead of you, this keeps the back flat
• when you can't bend forwards anymore with a flat back relax the chest and head towards the leg, relax the arms towards the floor and if your hands reach the floor just relax them without placing your weight on them
• if you cannot stretch down very far, that's fine. Just relax your hands and arms either side of your legs
• breathe slowly and deeply and try to consciously relax the muscles in the legs, buttocks, back and shoulders
• take 5 long slow breaths before lifting the head, shoulders and chest to make a flat back and come to standing on an in-breath
• bring both feet together and stand straight for a few moments before doing the posture with the right leg forwards

The key to this posture is deep, slow breathing and not rushing. It takes around 30 seconds for a muscle to start relaxing in a stretch so take your time. If at any time you feel pain, or your legs shake, then slowly come out of the posture and next time don't try to push yourself so hard.