The following stanza makes it clear that we speak of yoga in the sense of strenuous ascetic efforts, which have many similarities to the mortification practices of proto-yoga and the early yoga of the Upanishads:
Constantly practicing yoga, he should control his breath repeatedly, generating the most extreme heat up to the very tops of his hair and nails (2.3)
However we also notice a difference from proto-yoga and Upanishad yoga. The yoga described in the Dharma-sutras is not the meditative-in-deep-trance-yoga we faced in some of the Upanishads. It is not the yoga of mystical atman and brahman realisation. It is the yoga of strenuous effort aimed at maintaining social differences expressed in terms of purity. I will return to this purifying yoga’ as it is typical of the much later Dharma-sastras.
Breathe fully, allow the ribs and waist area to spread Yoga hip openers , then release and repeat on the other side. Purpose: To extend and strengthen the Yoga hip openers back of the body and open the chest and shoulders, extending the spinal range. Contraindications: Absolute Chiari malformations; Relative sacroiliac joint derangement, scoliosis, facet syndrome, spinal stenosis, vertebral fracture, severe osteoporosis risk of fracture. Props: A yoga mat and a blanket. Avoiding pitfalls: Keep the legs and feet parallel. Relax your neck, throat, and jaw as you breathe. If your neck is stiff, begin with a folded blanket under your shoulders and upper arms as shown. Avoid squeezing the buttocks too tightly.