What is the difference between equilibrium balance and stability?

Definitions

• Balance
  • The ability to maintain the body center of gravity over its base of support (NSCA 2012).
• Stability
  • The ability to return to a desired position or trajectory following a disturbance. (NSCA 2012).
• Equilibrium is the state of no acceleration (no change of speed or direction) of body.
  • Static Equilibrium refers to the body at rest or motionless.
  • Dynamic Equilibrium refers to the body in motion with unchanged acceleration created by balanced applied and inertial force
• Center of Gravity:
  • The point at which all body mass is equally balanced or equally distributed in all directions.

Controversies

Proprioceptive ability does not appear to be related to performance (NSCA 2012). Bompa (2015) suggests that the importance of balance training in sports and fitness is more of an unfounded speculation than a certainty.

"...balance is not and never has been considered a limiting factor for performance.”

Despite the reality of biomechanics, some people still believe that balance training needs to be trained as a separate element in training like strength or flexibility. In actuality, balance is simply trained as a by-product of other training abilities such as strength, power, agility, and flexibility. (Bompa 2015)

Athletes need a minimum amount of balance and stability. Rather than attempting to maximize balance and stability traits in all those of average abilities, fitness professional should direct their efforts toward those who are considered poor performers and assign remedial work based on their deficiencies. (NSCA 2012)

The equipment promoted as improving balance has little, if any, effect on an athlete's performance. Children in the initiation stage of development, such as kindergarten, might really enjoy some of these balance exercises. Maintaining balance on a balance board certainly involves some degree of difficulty. However, to claim that these exercises can positively affect sport training or that repeating some of these exercises will improve athletic performance is an insult to any good student of sport science. (Bompa 2012)

Specificity of Balance, Proprioception, and Core Stability

For any sport, the optimal method to improve balance, proprioception, and core stability is to practice the skill itself on the same surface on which the skill will be performed during competition. There is little transfer between balancing skills because balance is skill specific. For example, having a gymnasts practice on a wobble board balance will not be improved balance on the beam. Similarly, having a baseball pitcher stand on a foam roller while throwing a medicine ball may not improve proprioception when throwing from a mound. Likewise, having a football player stand on a stability disks while performing squats may not improve core stability when running through a defensive line. Performing resistance exercises on stability balls, foam rollers, wobble boards, and variations of such equipment has not been shown to enhance sports related skills. (Willardson 2004)

Decreased Performance on Balance Equipment

Subjects strengthened on stable surfaces performed significantly better in athletic measures than subject doing the same exercises on inflated rubber disks (Cressey 2007). Cressey, et al (2007) concluded

“Using inflatable rubber disks attenuates performance improvements in athletes.”

Unstable devices account for 44% less muscle activity and 70% less muscle force output than stable surfaces. (Behm 2002)

Efficacy of BOSU Balance Trainer for Core Muscle Activation

The activity of core muscles (rectus abdominis, external oblique abdominis, transversus abdominis/internal oblique abdominis, and erector spinae) were compared when standing on a BOSU balance trainer versus a stable floor while performing various exercises (back squat, deadlift, overhead press, and arm curl). No significant differences of core activation were observed between the BOSU and stable floor when performing exercises with the same workload 50% of 1-RM. The researches concluded that this study did not demonstrate any advantage in using the BOSU Balance Trainer and these lifts can be performed while standing on a stable floor without losing any training benefits of core muscle activation. (Willardson 2009)

Balance Training During Rehabilitation

Balance performance and robustness are impaired following injury. This is likely due to compromised strength, decreased proprioception, and altered programming. Although balance training, in itself, does not appear to decrease risk of re-injury, risk of re-injury may be reduced when balance training is one component of an intervention program. Proprioceptive deficits caused by an injury can be improved during the rehabilitation process, but there's no evidence to support the ability to improve proprioception and healthy, asymptomatic people. (NSCA 2012)

Reducing ACL Injury Risk in Female Athletes

Myer (2006) suggests both plyometric and dynamic stabilization/balance exercises should be included in injury-prevention protocols. Plyometric training affects sagittal plane kinematics primarily during a drop vertical jump, whereas balance training affects sagittal plane kinematics during single-legged drop landing. (Myer 2006)

Weight Training Decreases Fear of Falling in Elderly

Elderly (ages 67 to 97 years of age) who participated in a free weight program reported a decreased fear of falling. They also increased functional performance, increased perception of health, and decreased need for medication. (Brill 1998)

Factors Increasing Stability

• Center of gravity falls within base of support
  • decrease in stability when center of gravity becomes near edge of base
• Larger base
• Greater weight
• Lower center of gravity
• When anticipating an oncoming force
  • place center of gravity near the side of base of support expected to receive force
  • extending base of support in direction of expected force
• Greater friction between body and surfaces it contacts
• Rotation about axis
  • moving cycle is easier to balance that stationary cycle
• Kinesthetic physiological functions
  • vestibular system, vision, touch, and kinesthetic awareness

Movement

• Walking throws body in and out of balance with each step
  • placing the center of gravity beyond base of support
• A large component of sprint acceleration is created by falling forward
  • placing the center of gravity beyond base of support
• Jumping attempts to raise body's center of gravity upward
• Also see calculating Center of Gravity.

Balance Exercise Examples

• Balance Board
  • Stand
  • Squat
• Medicine Ball
  • Close Grip Pushup
  • Windmill Push-up

References

Behm DG, Anderson K Curnew RS (2002). Muscle force and activation under stable and unstable conditions. J Str Cond Res. 16: 416-422.

Bompa T Carrera M (2015). Conditioning for Young Athletes. Human Kinetics.

Brill PA, Matthews M, Mason J, Davis D, Mustafa T, Macera C (1998). Improving functional performance through a group-based free weight strength training program in residents of two assisted living communities. Physical and Occupational Therapy in Geriatrics, 15(3), 57-69.

Cressey EM, et al. (2007). The effects of ten weeks of lower-body unstable surface training on markers of athletic performance. J Str Cond Res. 21(2): 561-567.

Myer GD, Ford KR, McLean SG, Hewett TE. (2006) The effects of plyometric versus dynamic stabilization and balance training on lower extremity biomechanics. The American Journal of Sports Medicine, 34(3): 445-455.

NSCA (2012) NSCA's Guide to Tests and Assessments. Human Kinetics.

Willardson JM, Fontana FE, Bressel E (2009). Effect of surface stability on core muscle activity for dynamic resistance exercises. Int J Sports Physiol Perform. 4(1), 97-109.

Willardson JM (2004). The effectiveness of resistance exercises performed on unstable equipment. Strength and Conditioning Journal; 26(5), 70-74.