Dorsal Lumbar Fascia Stretch

Proceeding cranially, after considering major lower extremity muscles and stretching techniques, we come to the trunk. 
Ever notice, when you get up in the morning and you stretch with arms overhead and leaning backwards, opening the front chest and abdomen, bending to the sides with arms stretched overhead or even rounding the mid/upper back and shoulders? Aah! That feels so good. All these are stretching muscles in the trunk. Let’s see them one group at a time.
Today we will see the DLF or the dorsal-lumbar fascia, so known because of the span of fascial connective tissue extending in the dorsal(thoracic) and lumbar regions of the spine/trunk. The fascia is a visco-elastic tissue that contracts (resulting in stability through contractions of the various muscles which insert via aponeurosis into this fascial sheath) and expands (allowing mobility during forward and lateral flexion movements of the spine). 
This fascial sheath encases various muscles and accepts muscle insertion forming aponeurosis. The posterior layer (deep lamina) with the middle layer encases the iliocostalis, longissimus, multifidus, and erector spinae muscles. Laterally, this sheath forms the aponeurosis with transversus abdominus. The posterior layer (superficial lamina) also receives insertion of latissimus dorsi forming aponeurosis with latissimus dorsi. The quadratus lumborum (QL)muscle lies between the middle and anterior layers. The psoas muscle lies anterior-most, being separated from the QL by the anterior layer. The fascia itself originates from the spinous processes of the dorsal and lumbar vertebrae, supraspinous and interspinous ligaments, the iliac crest, SI joint and sacrotuberous ligament. Thus, it covers a large, diamond-shaped area, in the back. 
Together with the abdominal muscles (transversus abdominus and obliques) and back extensors (Longissimus, iliocostalis and multifidus), it forms a corset-like structure in the trunk, providing static postural and dynamic stability during the various movements. The latissimus dorsi and contralateral gluteal muscles and the internal oblique with the contralateral hip adductors exert forces through the DLF, contributing to trunk stability. Hence, even though, the DLF is not a muscle, it has a major contribution to healthy functioning of the trunk, both during static postural maintenance and dynamic movement in various planes.
Now, let us consider the technique for stretching the Dorsal-Lumbar Fascia or DLF, bilaterally and symmetrically.
Passive stretch:
In the supine position, the therapist brings the hips and knees into maximal flexion with knee to chest position, thus flexing the lumbar spine with posterior pelvic tilt, lifting the buttocks off the mat. The head and neck are flexed bringing the chin to knees, thus rounding the back completely. 
It is important to note, that mechanism of stretch through tension in passive stretch (stretching fascial tissue throughout its course by posterior pelvic tilt and spinal flexion) is different from an active stretch in which case, the contraction of muscles and resulting tension in the fascia contribute to provide stability to the spine and pelvis during functional movements.
Active Static Stretch:
In this post, we are basically looking at symmetrical, bilateral stretch. Hence any forward bending activity is effective.
i) Paschimottasana: Begin on the floor mat in long sitting position or dandasana. Allow the low back musculature to contribute to sitting upright. Hands are placed besides the hips on either side with fingers pointing forwards. Elevate the arms overhead, elongating the spine 
(transversus abdominus and latissimus dorsi engaged). Slowly rock back and forwards by tilting pelvis and bring hands to knees, shins and big toes of feet in succession. Deepen the pose during exhalation. Gently bring the elbows to floor by side of knees and lower the forehead to the knees. Hold for 5 to 30 seconds. To release, slightly bend the knees, lift head and arms overhead and come into dandasana.
Active dynamic stretch:
i) Balasana: Also known as child’s pose or prayer pose. Begin in kneel sitting pose or vajrasana with an upright, elongated, spine that is engaging of transversus abdominus, erector spinae, and multifidus. The feet should rest on dorsum with toes pointing behind or slightly inwards. Sit completely with buttocks/back of thighs resting on the heels. Bring the knees apart. Begin bending forward at the hips and lower the torso to the ground, bringing the forehead to the floor. The arms are outstretched overhead to stretch the DLF through the latissimus dorsi. Hold for 5 to 30 seconds, then release by bending the elbows and pulling hands towards torso, lift the forehead off the ground, sit up by extending at hip and tilting pelvis anteriorly towards neutral.
ii) Pavanmuktasana: This active stretch is much the same as a passive stretch in supine position. Bend the hips and knees from neutral supine position, so that the heels are as close to buttocks as possible. Lift the feet off the floor bringing the knees to chest and lifting tailbone up, tightly circle arms around the shin and pull up while raising the head from the floor to bring the forehead/ chin to knees. Deepen pose on exhale and hold for 5 to 30 seconds, then release by lowering head to floor first, next the pelvis/tailbone and finally and expands he feet. Straighten the legs to come back to supine position.
Stretch with equipment/tools:
Foam roller stretch: Place the foam roller on the mat. Sit on the mat with the foam roller placed perpendicular to the trunk/spine. Lie down with upper thoracic spine on the foam roller, keeping the hip and knee flexed with feet on the floor. Cross arms and place them over stomach/abdomen. Roll upwards/cranially on roller slowly and hold in places which are tender (trigger points), to allow them to release. Progress in small increments rolling back and forth along the back of trunk till you reach the sacrum. You can also place the foam roller lengthwise along spine and roll it outwards to release the diagonally or laterally arranged connective tissue.