What Ah, it's winter time again in Wisconsin. I know this to be true for several reasons:

a) I have had my hair freeze in ringlets and break off in my hand;

b) I look like the Pillsbury Dough Boy (pasty, white, and sporting a very plump coat); and

c) Twice this week, I have slipped on the same patch of ice which extends from my porch to my car.

During this process, I executed-- if I may be so bold -- a rather spectacular squat-split movement, not often seen outside Bambi movies. The cool thing? I didn't break a thing.

I count myself blessed. Many aren't. As a PT, I have had the opportunity to work in a trauma hospital, a skilled nursing facility, and in people's homes. I have come to the conclusion that for many people, natural movement has narrowed to a 3 x 2 foot area.

Because of the fear of falling, there is no risk-taking behavior: no sudden lunges to grab the telephone on the fly, no casual forward leans to snag the dropped set of car keys, no plopping down in the favorite chair.

There is, as a matter of course, no plopping down.

For these people, falls are a constant threat, in good weather and in ill. This fear translates to an unwillingness to move without external support. And while an external support, such as a walker or cane, may prevent a fall today, I'm starting to believe it can set up a tomorrow full of risk.

We've all seen the "shopping cart push" of a patient with a wheeled walker. Walker, left foot, right foot. Center of mass maintained inside (artificially widened) base of support. The patient moves in a constant linear movement, almost assuredly in a forward direction.

So what happens when an accident or freak of fate forces that person's mass outside that carefully maintained base of support? The body has no engram or natural protective mechanism off which to operate. What often transpires is a fall.

So what can we do? Well, we can't dash about under the cloak of darkness poaching people's walkers. Besides being rude, I'm pretty sure it's not considered a proper intervention under the Guide to Physical Therapy Practice: Part II.

As a point of fact, we're the ones who show people how to be safer ambulators with external supports. I know walkers and canes are necessary. But their natural byproduct -- the reduction of a willingness and ability to safely move outside a stable base -- must be counterbalanced in some other way. My suggestion? Introduce your patient to the benefits of water-based balance training.

Why water?
Many therapists have come to believe that improvement in balance is caused by the ability to make movement errors and correct for them. [1-6] In other words, balance reactions and other proprioceptive tasks are inherently trainable in the right environment.

I would hypothesize that the pool provides an exceptional environment in which to work. Why?

1. Patients may be challenged beyond their limits of stability in the water without the fear of consequences of falling which are often present with land-based balance training. The worst case result of an uncorrected loss of balance is a fall into a compliant fluid (water) and not a fall to a noncompliant solid (the ground). Thus, the patient may be challenged to move outside his base of support without fear of traumatic consequences. This reduction in patient anxiety may encourage the patient to attempt tasks which he would not attempt on land. It becomes possible to elicit balance challenges which the patient has both the time and mental confidence to combat. On land, without the assistance of such aquatic properties, the resultant balance responses may be incomplete or absent.

2. Patients who move their limbs and trunk through the water elicit greater somatosensory input than they would by moving the same body parts through air. This is especially true when the movement is rapid, increasing drag. Water is more viscous than air, and resistance to flow through water is greater than resistance to flow through air. Richley Geigle et al believe that the water's viscosity causes "distention or stretch of the skin" resulting in stimulation of rapidly adapting mechanoreceptors. [7] They further postulate that this may increase the amount of proprioceptive input into the brain. Of course, it's important to note that quiet standing in water may actually diminish the sensory input received by the body. Mano et al found that when a person stands unmoving in deep water, there is a decrease in the activity of the leg muscles and the sympathetic activity of the sole of the foot. [8] Immersion alone (without movement) resulted in less motor activity for postural muscles such as the calf, and less sensory input to the skin (and probably joint) receptors which record weight bearing.

3. In the pool, patients have an elongated period of time in which to respond to loss of balance episodes. In the water, patients are surrounded by a viscous fluid which retards the speed of movement. This viscosity prevents rapid falling and extends the period of time in which a patient can react. 4. Finally, in the water, patients can be easily challenged to problem-solve complex balance situations. Since the water offers a three dimensional environment of both support and resistance, therapists can "create multiple combinations of joint angles and planes of motion which are assisted, supported or resisted to various degrees." Buoyancy makes it easy to quickly alter training scenarios without worrying about risk of falls.

Who says it works?
It's all well and good to hypothesize that balance can be improved by training in water. But does the literature bear this out? Simmons and Hansen tested the effects of exercise, immersion in water, socialization and a combination of all these factors on balance control. [9]

Their research subjects were divided into 4 groups: water sitters, land sitters, water exercisers, and land exercisers. These 4 groups were created to attempt to isolate the factors which improve gait: exercise alone (land exercise), water immersion (water sitting), socialization (land sitting) or exercise in a medium which permitted multiple "movement errors" without fear of falling (water exercise).

All groups met for 45 minutes, 2x/week for 5 weeks with the supervision/instruction of a physical therapist. Exercise in the water enhanced the functional reach (FR) of the subjects more than did socialization, water immersion or exercise alone.

Functional reach improved over 35 cm by week 5 and resulted in continued participation in exercise, no orthopedic injuries and some subjects discarding their assistive gait devices. Additionally, water exercisers adhered to their program, as evidenced by better attendance rates.

The authors postulate that the improvement shown by the water exercisers was due to their ability to make and correct for movement errors in a viscous, safe environment which provided proprioceptive feedback to movement. The authors felt that land-based exercise may be too intimidating for those with balance deficits; the cost of loss of balance is much greater than it is in water.

Finally, the authors postulated that the water's turbulence, inherent destabilizing effect, and depth-dependent buoyancy effect may have enhanced the variability of practical effect needed to learn compensation for loss of balance.

Conclusion
Therapists interested in learning more about the effects of immersion on proprioception are not left wholly without guidance. [10-12] The important consideration seems to be to provide patients with an environment in which they can practice balance tasks without a fear of the consequences. Even during a Wisconsin winter.

References
1. Gentile AM. "Skill acquisition: action, movement and neuromotor processes". In: Carr JH, Shepherd RB, Gordon J et al. Movement Science: Foundations for Physical Therapy in Rehabilitation. Rockville, MD: Aspen Publishers Inc; 1987: 93-154.

2. Higgins S. Motor skill acquisition. Phys Ther. 1991; 71: 123-139.

3. Schmidt RA. "Motor learning principles for physical therapy". In: Lister MJ (ed). Contemporary Management of Motor Control Problems. Alexandria, VA: Foundation for Physical Therapy; 1990: 49-61.

4. Winstein CJ. "Designing practice for motor learning: clinical implications". In: Lister MJ (ed). Contemporary Management of Motor Control Problems. Alexandria, VA: Foundation for Physical Therapy; 1990: 65-76.

5. Crutchield CA, Barnes MR. Motor Control and Motor Learning in Rehabilitation. Atlanta, GA: Stokesville Publishing Co; 1993.

6. Nashner LM. "Sensory, neuromuscular, and biomechanical contributions to human balance." In: Duncan PW (ed). Balance: Proceedings of the APTA Forum. Alexandria, VA: American Physical Therapy Association; 1990: 5-12.

7. Richley Geigle P, Cheek WL, Gould ML, Hunt HC III, Shafiq B. Aquatic physical therapy for balance: The interaction of somatosensory and hydrodynamic principles. J Aquatic Phys Ther. 1997; 5(1): 4-10.

8. Mano T, Iwase S, Yamazaki Y, Saito M. Sympathetic nervous adjustments in man to simulated weightlessness induced by water immersion. Sangyo Ika Diagaku Zasshi. 1985; 7 (Suppl): 215-227.

9. Simmons V, Hansen PD. Effectiveness of water exercise on postural mobility in the well elderly: an experimental study on balance enhancement. J Gerontol. 1996; 51A(5): M233-M238.

10. Lord S, Mitchell D, Williams P. Effect of water exercise on balance and related factors in older people. Aust J Physiother. 1993; 39(3): 217-222.

Disclaimer
The information presented in this article is meant to be a summary and educational in nature. It is not meant to serve as a substitute for legal advice.

Author Bio
Andrea Poteat Salzman, MS, PT is the owner of two businesses, the Aquatic Resources Network and Concepts in Physical Therapy. She has received both the prestiguous Aquatic Therapy Professional of the Year Award (Aquatic Therapy and Rehabilitation Institute) and the Tsunami Aquatic Therapy Award. Salzman is well-regarded within the industry as:

• Editor-in-Chief of an aquatic therapy trade journal and newsletter;
• Author of over a dozen publications, including the soon-to-be-released Evidence-Based Aquatic Therapy textbook;
• Freelance author and columnist;
• Aquatic therapy seminar instructor;
• Adjunct faculty and research advisor, St. Catherine Physical Therapy Program, Minneapolis, MN;
• Immediate past manager of therapeutic aquatics, St. Paul Ramsey Medical Center, St. Paul, MN;
• Researcher and grant recipient examining aquatic exercise vs. land-based exercise.

She may be reached via e-mail at asalzman@aquaticnet.com