Read Dario's reply:
Students with repetitive stress injuries should minimize pressure on their hands; otherwise, the irritated tissues never get a chance to heal. So I don't think it's a good idea to practice Downward Dog, Upward Dog, Plank, and other such poses on the fists. This approach may be less painful than practicing on the palms, but it won't eliminate the strain. In addition, practicing with closed fists exacerbates tension in the shoulders and upper back, which can contribute to the problem.
Many people think these injuries are a localized problem caused by overuse of the hands and wrists. But the damage usually stems from both overuse and a chronic postural imbalance. When you sit for hours at a computer, for example, you tend to draw your head forward and round your shoulders and upper spine. The muscles of the upper back constantly fight against these tendencies, becoming chronically tight and fatigued.
In dealing with carpal tunnel and similar conditions, I've found it to be extremely helpful to release the muscles of the upper back and realign the spine in its natural curves. Making fists has the opposite effect: It tightens the area between the upper thoracic spine and the tops of the shoulder blades, intensifying the muscular and energetic congestion that may have originally contributed to the injury.
Have your students modify their Downward Dog by practicing the pose with wall ropes around the upper thighs; this reduces pressure on their hands while still allowing effective work in the shoulders and upper back.
If wall ropes aren't available, ask your students to partner up; a yoga buddy can produce a similar effect by drawing back on the ends of a strap placed across the top of the student's thighs. (The student shouldn't return the favor; people with repetitive stress injuries should avoid grasping a strap like this.)
Students with neither wall ropes nor a yoga buddy can make a loop with a yoga strap, wrap it around both knobs of an open door, step inside the loop, and practice Downward Dog with the strap at the top of the thighs.
Dario Fredrick has studied yoga for 12 years, primarily with Iyengar-influenced teachers in the United States and also with the Iyengars in India. Fredrick, who holds a master's degree in exercise science, integrates his experience as an exercise physiologist with his yoga instruction. He teaches public classes and workshops in Northern California. Email: email@example.com.