The Stability Trainer in Functional Exercise

The Stability Trainer in Functional Exercise
by Craig Liebenson


The goal of any fitness program is to improve performance in activities of daily living (ADL’s), job demands (JD’s), or sports and recreational activities (SRA’s). Many exercises “isolate” problem areas, but don’t mimic the way muscles are used in actual activities. Such exercises may be important stepping stones in training, but they are not ends in themselves. This article will show how to use a new balance training device – the stability trainer – to enhance functional training.

A valuable training principle to understand is the SAID principle which means that training causes “specific adaptation to imposed demands” (Sale 1991). These adaptations are specific to the length, movement and speed of the exercise trained (Rutherford 1988). Examples include:

  • Trunk flexors (abdominals) trained in the sitting position become stronger there, but not in other positions such as standing.
  • Knee extensors (quadriceps) trained on the seated knee extension progressive resistance machine do not become stronger on a bicycle (Rutherford 1988).

An excellent example of functional exercises are the 3-D lunges and single leg balance squats taught by Gary Gray, P.T. (Gray 2001). These utilize a “star matrix” so that all 3 planes of movement can be simultaneously trained (front/back; side to side; and twisting) (see figure 1). When trained on an unstable surface such as a stability trainer or balance board the effects can be amplified (Janda 1996). Balogun demonstrated that by exercising on balance tools lower extremity strength improved more than if 4 separate resistance machine exercises are performed (Balogun 1992). Balance training has been incorporated into ankle and knee rehabilitation since the 1960’s (Freeman 1965, Caraffa 1996, Seidler 1997, Tropp 1995). The ancient Tai Chi system has used this for thousands of years and now recent studies prove its value especially in the elderly for prevention of falls (Brandt 1981,Wolf 1996, Wolfson 1996).

The star matrix of Gary Gray, P.T.


An excellent way to start is with an assessment of balance ability. Try to stand on 1 leg with eyes closed for 30 seconds (see figure 2) (Bohannon 1984). A few warm-ups should be attempted first before recording the best time achieved. The test is stopped if the other foot touches down; hopping occurs; eyes open; or either hand touches a wall or other support. Normal ranges are as follows:

  • 20-49yrs/24-28 sec.
  • 50-59 yrs/21 sec.
  • 60-69 yrs/10 sec.
  • 70-79 yrs/4 sec.
Figure 3
Single Leg Balance
on the Stability
Figure 4
Dynamic Lunge on the
Stability Trainer

Exercise should begin on the floor in the single leg stance balance position. Start with your eyes open and attempt to perform 6 repetitions with 10 second holds/repetition. This should be performed twice/day. When you can accomplish this then progress to performing it with eyes closed.

The next progression is to balance on 1 foot on the Stability Trainer (see figure 3). Again perform it first with eyes open and then once mastered with eyes closed. Always progress to the next level of exercise when you can perform 6 repetions with 10 second holds/repetition.

The next progression is to perform a dynamic lunge exercise first on the floor and then on the Stability Trainer (see figure 4). These exercises are performed slowly in each direction showed by the Star Diagram (front, side, and back). When 12 repetitions can be performed slowly without jerky movements then progress to lunging onto the Stability Trainer.

Another challenging functional exercise is the single leg squat (see figure 5). This should also be performed first with eyes open until 12 slow repetitions can be controlled. Then it can be progressed to eyes closed.

Then both eyes open and closed can be performed on the Stability Trainer.

Both lunges and single leg squats can also be performed with movement in all 3 planes of motion by adding arm reaches (see figures 6 and 7). Eyes open, eyes closed, on the floor, and on the Stability Trainer are the options.

Single Leg Stance
Balance Test
Figure 5
Single Leg Squat
Figure 6
Back Lunge with Arm Reach
Figure 7
Single Leg Squat with Arm Reach
Figure 8
Golfer Exercise with Stability Trainer

The final common pathway for functional exercises are movements which mimick the sports or activities an individual performs. The Stabilty Trainer is ideal for challenging the balance, coordination, strength and endurance of the individual in these functional positions and movements (see figure 8).


The key is to keep your functional exercises progressing to greater and greater challenge. By incorporating both functional whole body movements and balance training the deep “core” muscles can be trained which are needed to stabilize your joints and prevent injury. Table 1 summarizes the exercises shown here.

Table 1
Exercise Progressions

  1. Single Leg Stance Balance
  2. Dynamic Lunge
  3. Single Leg Squat
  4. Back Lunge with Arm Reach
  5. Single Leg Squat with Arm Reach
  6. Golfer Exercise


  1. Bologun JA, Adesinasi CO, Marzouk DK 1992. The effects of a wobble board exercise training program on static balance performance and strength of lower extremity muscles. Physiother Can 44:23-30.
  2. Bohannon RW, Larkin PA, Cook AC, Gear J, Singer J 1984. Decrease in timed balance test scores with aging. Physical Therapy 64;7:1067-1070.
  3. Brandt T, Krafczyk S, Malsbendend I 1981. Postural imbalance with head extension: improvement by training as a model for ataxia therapy. Ann NY Acad Sci 636-649.
  4. Carrafa A., Cerulli G, Projectti M, Aisa G, Rizzo A 1996 Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arth 4(1):19-21.
  5. Freeman MAR, Dean MRE, Hanham IWF 1965 The etiology and prevention of functional instability of the foot. J Bone and Joint Surg (Br) 47B: 678-685.
  6. Gray G 2001. Rehabilitation Institute of Chicago. Functional approach to musculoskeletal system II Seminar, October.
  7. Janda V, Va’ vrova’ M 1996. Sensory motor stimulation. In Liebenson C (ed) Spinal Rehabilitation: A Manual of Active Care Procedures. Williams and Wilkins, Baltimore.
  8. Rutherford OM 1988 Muscular coordination and strength training, implications for injury rehabilitation. Sports Med 5:196.
  9. Sale D, MacDougall D 1981 Specificity in strength training:A review for the coach and athlete. Can J Sport Sci 6:87.
  10. Seidler R, Martin PE 1997. The effects of short-term balance training on the postural control of older adults. Gait and Posture 6:224-236.
  11. Tropp H, Askling C, Gillquist J 1995. Prevention of ankle sprains. Am J of Sports Med 4:259-262.
  12. Wolf SL, Barnhart HX, Kutner NG, et al., 1996. Reducing frailty and falls in older persons: An investigation of Tai Chi and computerized balance training. JAGS 44:489-497.
  13. Wolfson L, Whipple R, Derbe C, et al., 1996. Balance and strength training in older adults: Intervention gains and Tai Chi maintenance. JAGS 44:498-506.

Craig Liebenson,DC
Los Angeles, California