I have a client who is wearing "barefoot technology" shoes (designed to strengthen and tone the lower body due to proprioceptive elements) to our training sessions. It is very hard to differentiate between her balance/coordination issues and what seems to be caused by the shoes. Is there any scientific evidence that these are a good idea? I know it is supposed to mimic barefoot walking, but it concerns me that she is wearing these for a good portion of the day (walking, tennis and strength training).
Shoes that properly incorporate barefoot technology are a great idea and long overdue. And yes, there is good scientific evidence to support training in these types of shoes.
Some of the main concepts top trainers embrace today in regards to functional training include strengthening of stabilizer muscles, moving through natural range of motion and enhancing sensory awareness and balance responses.
As a whole, the sports/fitness industry has moved towards "functional" training. In an effort to recruit more stabilizer muscles and move more naturally, we've gotten away from training on machines with fixed paths of motion. We are also getting clients off of benches and eliminating the use of weight belts. For example, rather than having a bench or weight belt externally stabilize an athlete's spine, we have him develop neural control and strength of the core musculature. This gives him the ability to dynamically stabilize the spine on his own.
But ironically, while this "functional" philosophy has been commonly applied at the level of the spine, or shoulder girdle, its application at the foot is lacking. Many of the industry's training experts who would scoff at wearing a weight belt turn around and recommend orthotics and supportive shoes for their clients’ feet. This inconsistency in philosophy simply amazes me. If a client’s feet are weak and collapsing, then train his feet. Develop the same neural control and strength you would for any other body part.
Senior researchers at the Nike Sports Research Lab, Jeff Pisciotta and Helen Woo, and their team have studied barefoot training extensively. They and other European researchers have shown that subjects training in shoes incorporating proper barefoot technology do receive benefits. Athletes and clients who properly train in "barefoot" conditions recruit and strengthen the intrinsic muscles of the foot, use a more natural/full range of motion in the foot and have increased sensory awareness, both tactily and proprioceptively.
However, you are right to be concerned that your client could possibly wear these shoes too often, especially during the first week or so. Since "barefoot" training shoes require clients to use their foot musculature more, soreness and overtraining can occur. Stress should be applied progressively. While I haven't yet recommended competing in "barefoot" shoes, most of the athletes I train can do full workouts in them after two to three weeks.
To get your client training in "barefoot" conditions, use proper progression. It makes perfect sense from a functional perspective.