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Research Review By Dr. Jeff Muir©

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Date Posted:

April 2014

Study Title:

Whole-body vibration training improves balance, muscle strength and glycosylated hemoglobin in elderly patients with diabetic neuropathy

Authors:

Lee K, Lee S & Song C

Author's Affiliations:

Department of Physical Therapy, Sahmyook University, Seoul, Republic of Korea.

Publication Information:

Tohoku Journal of Experimental Medicine 2013; 231(4): 305-314.

Background Information:

Each year, one-third of individuals aged 65 and over experience a fall, 10-15% of which result in serious injury (1). These incidents necessitate a period of recovery that involves prolonged immobilization, while the fall itself exerts a significant psychological impact, often resulting in a subsequent fear of falling. As a result, patients’ mobility and ability to perform their normal activities of daily living (ADLs) can be severely compromised.

Patients with chronic disease are more prone to serious damage and complications after a fall, a fact which is prevalent in elderly diabetic patients, as they are more likely to suffer from peripheral neuropathies as a consequence of their illness. The increased postural deficits suffered by this group of patients decrease their ability to physically react to sudden or rapid postural changes, which may increase in fall risk (2). As such, exercises that improve posture and balance are theoretically beneficial for this group.

Whole-body vibration (WBV) training has been utilized for many rehabilitation purposes, including improving balance and muscle strength. It has shown potential as a modality to increase lower limb strength, bone density and functional mobility, in addition to limiting falls (3). It has not, to date, been evaluated in diabetic patients. Therefore, the purpose of this study was to determine the effects of WBV training on balance and strength in elderly patients suffering from diabetic neuropathy who are at high risk of falls.

Pertinent Results:

  • A total of 55 diabetic patients were included in the study and randomly assigned to one of three groups: WBV training plus balance exercises (n=19), balance exercises (BE) alone (n=18) or control (n=18).
  • One subject from the WBV group withdrew due to an insufficient participation rate; 2 subjects in the BE group were excluded because of incident fractures; and 2 in the control group were excluded because of home relocation.
  • HbA1c levels, used as a predictor of diabetes progression, showed significant improvement in the WBV group but not in the BE or control groups (p < 0.05). HbA1c was decreased by 0.8% in the WBV group whereas the comparator groups’ HbA1c levels actually increased by 0.2%. (EDITOR’S NOTE: this decrease is considered to be clinically meaningful as well, especially after such a short intervention period. Although more research is required, continuation of such a program may offer additional reductions in HbA1c levels.)
  • Postural sway, balance and functional abilities all showed significant improvement in the WBV group as compared with the BE or control groups (p < 0.05).
  • Muscle strength improved in the WBV group as compared to the BE and control groups (p = 0.001).

Clinical Application & Conclusions:

WBV, in combination with balance exercises, improved HbA1c levels, balance and muscle strength in a group of elderly patients suffering from diabetic peripheral neuropathy. Clinically meaningful improvements were noted in postural sway, a strong predictor of fall risk (a very important determinant of health in an aging population). Improvements were also noted in static balance, with WBV associated with significant increases in one-leg stand time and Timed-Up and Go Test times (TUG, a test of functional ability). WBV was also associated with an increase in lower-limb muscle strength, which itself is closely correlated with fall risk (4).

These findings must be mitigated by the fact that long-term exposure to WBV has been shown to have potentially dangerous side effects, including low back pain and muscle fatigue. It has also been shown to affect the digestive system, the female reproductive organs and the peripheral veins (5, 6). As such, it is important to consider safety protocols when developing exercise programs for elderly patients. Overall, WBV may be valuable for some patients but contraindicated in others, requiring a logical, individualized approach to prescription of this intervention. As more research emerges, we may obtain a clearer picture of which patients benefit most from this type of intervention.

Study Methods:

Patient Demographics:
95 patients were recruited for inclusion, of which 60 met the inclusion criteria.

Inclusion Criteria:
  • At least 65 years of age
  • At least one of the following: 2 or more falls during the previous 12 months, one fall plus a TUG test result of > 15 seconds, or recurrent unexplained falls
Exclusion Criteria:
  • Any musculoskeletal, neurological or vision impairment
  • Vestibular diseases with a diabetes-related etiology
  • Dementia
WBV Training:
Subjects stood upright on a platform and were vibrated in a 110 degree squatting position at an initial frequency of 15 Hz (amplitude 2 mm), increasing to 30 Hz over a 6-week period. WBV training sessions consisted of 3, 3-minute sessions with 1-minute intervals. Training sessions occurred approximately 3 times each week.

Balance Exercise:
Balance exercise consisted of a 10 minute warm-up period followed by a 40 minute session of static training, comprised of heel-toe raises with head movement and dynamic exercises involving walking, step-ups and bipedal jumps. A 10 minute warm-down ended each exercise session.

HbA1c Testing:
To evaluate diabetes progression, HbA1c – a form of hemoglobin that identifies the average plasma glucose concentration over prolonged periods of time – was evaluated by measuring the value of total HbA1c, measured using low-pressure cation exchange chromatography.

Posture & Balance:
Posture and balance were measured via a combination of tests, including: postural sway using a force platform; one leg stance; Berg balance scale; functional reach test; timed-up and go test and the five-times-sit-to-stand test.

Study Strengths / Weaknesses

Limitations:
  • The sample size was quite small, limiting our ability to extrapolate these results. We still need more research on this!
  • The study was not double-blinded. Although the assessments were conducted by an assessor blinded to the treatment groups, due to the nature of the interventions, participant blinding was not possible.
  • No long-term follow-up data was available after the initial intervention period.
Strengths:
  • The authors utilized an appropriate WBV protocol and included an exercise program known to improve balance.
  • The use of 2 intervention groups and a control group allowed for comparison of WBV and balance exercises against inactive controls.
  • The use of several clinical tests of balance and functional ability improved the robustness of the findings and mimicked typical practice patterns.

Additional References:

  1. Hausdorff JM, Rios DA, Edelberg HK. Gait vari- ability and fall risk in community-living older adults: a 1-year prospective study. Arch Phys Med Rehabil 2001; 82: 1050-1056.
  2. Menz HB, Lord SR, St George R, Fitzpatrick RC. Walking stability and sensorimotor function in older people with diabetic peripheral neuropathy. Arch Phys Med Rehabil 2004; 85: 245-252.
  3. Sitja-Rabert M, Rigau D, Fort Vanmeerghaeghe A et al. Efficacy of whole body vibration exercise in older people: a systematic review. Disabil Rehabil 2012; 34: 883-893.
  4. Jin HY, Kang YM, Kim CY et al. Morphological comparison of small nerve fibres in gastric mucosa in non- diabetic and Type 2 diabetic subjects. Diabet Med 2009; 26: 943-946.
  5. Seidel H. Selected health risks caused by long-term, whole-body vibration. Am J Ind Med 1993; 23: 589-604.
  6. LingsS, Leboeuf-Yde C. Whole-body vibration and low back pain: a systematic, critical review of the epidemio- logical literature 1992-1999. Int Arch Occup Environ Health 2000; 73: 290-297.

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