Your gait analysis is lying to you more than you think. The more difficult motor program your client is running occurs before the gait analysis even begins.

Even before you client walks back to your treatment room, there are several things that we may not be aware of. Gait initiation is a different and more complex motor program than the simple gait motor program.

Here is a little something we do in our clinics, all the time. When the session room is open for the next client, we greet our client in the lobby. We do not have our staff send them back to the room to change and wait for us. We watch them closely, but without them knowing. How does the client stand up? How do they initiate their gait cycle ? How is their balance? How do they carry their bags, purse, backpack ?
We ask them to head back to the session room to get changed, letting them think we are grabbing a drink of water. And then, in a sneaky manner, we watch them stand, initiate gait, and walk back to the room.
We do this, because, gait initiation is separate motor program. It requires several component parts, a squat, weight shift, double support balance acquisition, COP (center of pressure acquisition), step length precalculations, step width precalculation, foot strike targeting, weight shift again, initial weight transition, and then the gait cycle. And gait initiation is different and asymmetrical in people with pain, we know this for a fact in clients with painful osteoarthritis. These clients develop adaptive posturomotor strategies that shorten the monopodal phase on the affected leg.*
For many gait disorders, these are the component parts that will first show up if there is a problem in the system. Gait initiation is more difficult than gait perpetuation. Besides, how we walk when we do not think we are being watched, when we are carrying our things (purse, phone, bottle of water, backpack, etc) is how we typically walk. Clients will show all the goodies we need to see: the turned out foot, the hiked shoulder, the limps, the staggers, stumbles, speed, step width, and the like. We also get to see how they move in the shoes they live in, the heeled ones, the broken down ones, the work shoes.

So, when your client is having a formal treadmill gait analysis, what are you seeing? Their best behavior, or the truth ? One thing is for sure, you do not see the most important program the precedes their treadmill analysis, namely, how they get out of the chair and up onto the treadmill. This stuff matters.
There are clues everywhere, grab all of them, in as natural a manner as possible.

The Gait Guys

*Arch Phys Med Rehabil. 2000 Feb;81(2):194-200.
Asymmetry of gait initiation in patients with unilateral knee arthritis.
Viton JM1, Timsit M, Mesure S, Massion J, Franceschi JP, Delarque A.