Strength & Performance
Effect of Whole-Body-Vibration Training on Trunk-Muscle Strength and Physical Performance in Healthy Adults: Preliminary Results of a Randomized Controlled Trial
Journal: Journal of Sports Rehabilitation, 2016, 25: 357-363
Student Context: The purpose of this randomized cross-over study was to investigate the effects of a 4-min long, 2-mm vertically-vibrating vibration-exercise on muscle performance and body balance in healthy subjects. Sixteen volunteers (eight men and women aged 18-35 years) underwent both the 4-min vibration- and sham-interventions in a randomized order on different days. Performance- and balance-tests (stability platform, grip strength, extension strength of lower extremities, tandem-walk, vertical jump and shuttle-run) were done 10 minutes before (baseline) and 2 and 60 minutes after the intervention. In addition, the effect of vibration on the surface electromyography (EMG) of soleus, vastus lateralis, gluteus medius, and paravertebralis muscles was investigated during the vibration. The 4-min vibration-loading did not induce any statistically significant change in the performance- or balance-tests at the 2- or 60-min tests. Interestingly, however, the mean power frequency of the EMG in the vastus lateralis and gluteus medius muscles decreased during the vibration-intervention, indicating muscle fatigue, particularly in the hip region. It was concluded that a 4-min long, 2-mm vertically-vibrating vibration-stimulus did not induce changes in the performance and balance tests. Future studies should focus on evaluating the effects of different kinds of vibration-regimens, as well as the long-term effects of vibration-training, on body balance and muscle performance, and, as a broader objective, on bone.
Comments: This study used 6 exercises (side plank left and right, plank, sit up, sit up plus twist left and right – each position was held for 30 seconds with a 30 second rest interval. Thus there was only 3 minutes of exercise performed in each session. The intensity of the vibration platform was set to 30Hz with 1.6 g force (4 mm peak). In the Vibes Fitness studios this is a low intensity setting.
Journal: Journal of Strength and Conditioning Research, 2015, 29(5): 1367-1377
Study Context: Some studies have indicated that performing dynamic as compared with static position exercises while exposed to Whole Body Vibration might be beneficial but more evidence is required. This study had 21 young men and women participate in 4 exercise protocols: 5 sets of 10 dynamic squats without vibration; 5 sets of 30 second static squat without vibration; 5 sets of 10 dynamic squats with 30 Hz WBV for a total of 2.5 minutes; and 5 sets of 30 second static squats with 30 HZ WBV for a total of 2.5 minutes.
The results of this interesting study showed that in all conditions except dynamic squats with WBV, strength decreased after the exercise session. After WBV with dynamic squats, strength increased significantly.
Comments: This was the first study to compare two different types of exercise (static versus dynamic) under two different conditions (vibration or none). Researchers were unable to say why the strength improved after the single bout of dynamic squats when usually neuromuscular responses take 1 to 4 weeks to occur. They theorize that the stretch reflex activation led to increased muscle recruitment such that a supramaximal level of strength was provoked. This was strengthened by the fact that weakening occurred during the isometric conditions where there was essentially no change in the muscle length and therefore little if any stretch reflex activation.
Whole-body vibration training increases muscle strength and mass in older women: A randomized-controlled trial
Journal: Scandinavian Journal of Medicine and Science in Sports, 2010; 20(2): 200-207
Study Context: To determine whether 10 weeks of Whole Body Vibration (WBV) training has a significant effect on strength, muscle mass, muscle power and mobility in older women.
Twenty six women were randomly assigned to a WBV training group (n=13, avg age 79 years) or a control group (n=13, avg age 76 years). The training protocol consisted of a range of static and dynamic exercises that were progressed in vibration platform intensity (2 mm to 4 mm) and vibration frequency (20 to 40 Hz), a well as the number and sets of exercises according to the overload principle.
After the training period subjects were retested and only the WBV training group improved in strength (leg press increase 38.8%), muscle cross sectional area (Vastus medialis increased 8.7% and biceps femoris increased 15.5%). Mobility in the WBV training group also improved by 9%. All gains compared to the control group were significant. Interestingly muscle power remained the same in the WBV training group but decreased in the control group.
The researchers concluded that WBV training in older women produces a significant gain in mobility, muscle size, and strength and may be a useful training regime to counteract the loss of muscle size and strength associated with age related sarcopenia.
Comments: This study demonstrated impressive gains
Journal: Journal of Strength and Conditioning research, 2009; 23(2): 593-603
Study Context: This paper examines the literature with respect to vibration training in the athletic population, especially with respect to chronic changes in athletes. The authors conclude that there is evidence that vibration training provides a small benefit to maximal strength (1 repetition maximum) and power (countermovement jumps) but does not seem to enhance speed.
Comments: More studies are required to assess optimal vibration training protocols. Those studies that found insignificant strength improvements post- vibration training were exercising with squats but testing isometric and dynamic knee extension which may have had poor crossover. The studies that excised using vibration and squats and tested strength via leg press all found significant improvements.
In the power studies, higher intensity exercise appeared to provide the best results. For example, in the Fagnani et al. study of female athletes, they performed 8 weeks of dynamic unloaded exercises on the vibration platform at 35 Hz and 4 mm of displacement for a total of 14 g forces. The Ronnestad study used only 2-3 sessions per week for 5 weeks but each session consisted of 6 -10 repetition maximums. On the other hand, although the Owen group exercised twice per week for 6 weeks, they only performed 6-8 repetitions total at 30% RM.
Oscillatory whole-body vibration improves exercise capacity and physical performance in pulmonary arterial hypertension: a randomised clinical study
Journal: Heart, 2017; 0: 1-7
Study Context: Despite recent improvements, pulmonary arterial hypertension (PAH) remains a devastating disease with most patients still harbouring markedly reduced exercise tolerance and limited survival. In addition to pulmonary vascular disease and concomitant right ventricular dysfunction, physical disability is further exacerbated by the lack of physical activity in affected patients. The application of Whole Body Vibration (WBV) exercise has been successfully utilized to enhance moving velocity, muscle power and strength in young athletes and to improve physical performance balance and health related quality of life (HRQoL)in older patients. Furthermore, its application improved exercise capacity, lower limb performance, and HRQoL in patients with chronic diseases such as cystic fibrosis, multiple sclerosis and chronic obstructive pulmonary disease.
Researchers investigated 22 patients with stable, symptomatic PAH and randomized them to a WBV training or control group. Subjects in the WBV training group trained at 20 Hz, one hour per session for 16 sessions over 4 weeks. Both groups were retested and then the control group was put into the same WBV train regime for the second phase of the study.
Compared to the control group, WBV trainers showed significant improvements in the 6 minute walk test, muscle power and HRQoL. The combined analysis of all patients vs baseline indicated significant improvements in the 6 minute walk test (+38.6 m), peak VO2 (+65.7mL/min), anaerobic threshold (+40.9mL VO2/min), muscle power (+4.4%), and HRQoL (SF-36 +9.7 and LPH -11.5 points), all p<0.05. Researchers concluded that WBV training substantially improves exercise capacity, physical performance and HRQoL in patients with PAH on stable targeted therapy. This methodology may be utilized in structured training programs. Comments: Although this is the first study on WBV training with a PAH population, the authors of this study consider this a controlled pilot study due to the relatively small sample size of patients. Another limitation is the short training period of 4 weeks. It is unknown whether ceiling effect was reached in this period or whether maintaining the program would have led to even more significant gains. Furthermore, it remains unclear how long the beneficial effects of WBV training may last once training is stopped, or what period of WBV training may be sufficient to maintain a training effect.
Effects of Whole Body Vibration exercise training on aortic wave reflection and muscle strength in postmenopausal women with prehypertension and hypertension
Journal: Journal of Human Hypertension, 2014; 28: 118-122
Study Context: We Know that high pressure wave reflections predispose women to myocardial schema due to increased muscle demand. In addition to arterial ageing, there is greater loss of muscle strength and muscle mass in older adults. Leg muscle strength loss has been associated with increased mortality in older men. Because the age related increase in wave reflection, and subsequent risk for heart failure, is greater in women that in men, strategies that counteract or improve the negative consequences of wave reflection and muscle weakness in older women are needed.
Thirty women volunteered for this randomized parallel design study. Participants were postmenopausal (> 1 year without menstruation), overweight (body mass index > 25 kg/m2), prehypertensive (SBP > 120 mm Hg) and sedentary (< 60 min. of regular exercise training). Subjects were randomly assigned to a control or 6 weeks of WBV exercise training. THE WBV exercise group performed exercise 3 times per week at a platform frequency of 25-35 Hz, low to high amplitude, progressive duration (30-45 sec.) and progressive sets (1-2). The training protocol was similar to those previously used in the same population of women. The main findings were that 6 weeks of WBV training decreased wave reflection magnitude and aortic blood pressure. In addition, leg muscle strength improved significantly and this muscle strength increase was correlated with the decrease in augmented pressure. Comments: The researchers acknowledge that there was not an exercise without WBV group, but they justified the study design quoting a study by Figueroa et. al. where exercise without WBV does not induce an acute decrease in the augmentation index but an increase.
Osteoporosis & Osteopenia
Whole-body vibration improves neuromuscular parameters and functional capacity in osteopenic postmenopausal women
Journal: Menopause: The Journal of the North American Menopause Society, 2016; 23(8):870-875.
Study Context: Previous literature looking at strength improvements in osteopenic women have used different frequency and intensity of stimulus (20 to 45 Hz; 2 to 5 g forces; and a variety of exercises on the vibration platforms).
This study therefore sought to examine whether a different intensity of stimulus without any additional exercise elements would provide different results. Researchers used 60 Hz of vibrations frequency and 0.6 mm of displacement.
Women were randomly placed in a vibration group or a control group. Those in the vibration group stood on the vibration platform holding a support handle for 20 minutes, 5 days per week for 12 months under supervision. All women were instructed to not change any of their other physical activities.
After 12 months, the vibration group presented statistically significant improvements in isometric and dynamic muscle strength (hip flexors +36.7%; back extensors +36.5%; handgrip strength +4.4%, arm curl +22.8%), balance (unipedal stance test +6.8%) and mobility (timed up and go -9.2%), and flexibility (reach test +9.9%).
Comments: This was a fascinating study in that the researchers deliberately chose parameters and variables that were not previously studied. Once again, no exercise was performed on the vibration platform and the total g force applied was only 0.6. The tests were only taken at baseline and at one year so it would have been interesting to see if the vibration group’s results at say 4 and 8 months as well.
The volunteers of this study were identified as osteopenic by bone densitometry but the study did not include measurements of bone density at the end of the 12 month period.
The design of this study is the first to consider the effects of less than 1 g of vibration over time with out the additional benefit of exercise.
Effects of a short-term whole body vibration intervention on bone mass and structure in elderly people
Journal: Journal of Science and Medicine in Sport, 2014, 17: 160-164
Study Context: This randomized controlled trial took 49 elderly volunteers into a control or Whole Body Vibration group. The WBV group trained 3 times per week for 11 weeks. Both groups were assessed for bone related variables. At 11 weeks there were no significant changes in the bone density variables. The researchers concluded that this short duration of time was insufficient to induce bone density changes and that longer training periods were like required.
Comments: There are a few points to consider with this study. First, the participants stood on the vibration platform rather than exercise on it. Secondly the vibration parameters shown were chosen at 40 Hz and 2 mm displacement which is a peak g force of 6.4 G, however previous research showed that the optimal frequency for increasing bone density is 20 Hz.
Effects of Whole Body Vibration and resistance training on bone mineral density and anthropometry in obese postmenopausal women
Journal: Journal of Osteoporosis, 2014: 1-6
Study Context: One aspect of health that is particularly important for post menopausal women is that of bone mineral density. We know that physical exercise is helpful for bone mineral density but vigorous weight bearing exercise can also increase the risk of injuries. Since recent evidence shows that low levels of mechanical vibration can be strongly anabolic, and if these mechanical signals can reach the areas of the skeleton at greatest risk of osteoporosis such as the hip and lumbar spine, then vibration exercise could be used as a unique, non pharmacological intervention to prevent or reverse bone loss.
This Egyptian study divided 80 women (ages 50 – 68 years) with high body mass indices (BMI 30-36 kg/m2) into two groups: one group performed weight bearing exercise 3 times per week for 8 months while the second group performed Whole Body Vibration exercises 3 times per week for 8 months.
Both groups significantly improved their bone mineral density after the 8 months of exercise and both groups improved their body mass indices and waist to hip ratios. The highest values of R2 were found for the models incorporating vibration exercise plus BMI
Comments: The vibration training group spent a total of 20 minutes training of which 10 minutes was on the machine and 10 minutes were in rest intervals. The weight training group spent one hour in the gym exercises and the exercises were not the same ones used in the vibration training group. The researchers noted that the long training times such as those used in the non training group are one reason that compliance is often low and that similar gains were made in a shorter period of time with vibration exercise.
Journal: Al Ameen Journal of Medical Science, 2017; 10(1): 3-9
Study Context: This UK study was a joint project taken on by Abertay University, Dundee, the School of Medicine at the University of Dundee and Southamptom Solent University. In the UK only 43% of diabetic men and 32% of diabetic women achieve the recommended 30 minutes of exercise 5 days per week. It had been demonstrated that 15 minutes per week of high intensity exercise can also significantly improve insulin sensitivity, however the safety of this type of exercise for certain overweight diabetics was questioned. Researchers identified Whole Body Vibration Training (WBVT) as a time and intensity efficient workout.
Five healthy sedentary individuals undertook oral glucose tolerance testing prior to and after completion of a 6 week progressive WBVT program. These individuals showed a 9% reduction in plasma glucose area under the curve post training; the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) decreased by 21%; the Cedarholm index of insulin sensitivity was increased by 18%.
The conclusion of this study is that WBVT is associated with improved insulin sensitivity in could produce clinically relevant effects on fat metabolism in sedentary young people. Large scale studies are now necessary to assess the effectiveness of WBV in diabetic populations.
Comments: It would be fair to say that vibration training for diabetic individuals is promising but that more research is certainly needed before we can say anything definitively.
The effect of Whole Body Vibration therapy on the physical function of people with type II diabetes mellitus: a systematic review
Journal: The Journal of Physical Therapy Science, 2016; 28: 2675-2680
Study Context: The aim of this review was to systematically assess randomized controlled trials featuring application of WBV training to improve the physical function of people of type 2 diabetes mellitus (T2DM). Of 244 articles found, researchers chose only 5 to review.
Four articles assessed balance and mobility using the timed up and go test (TUG). Their results showed that the WBV groups demonstrated significant effect when compared to the control groups. This was regardless of treatment duration and parameters of WBV training. Further meta-analysis of the TUG results revealed a significant improvement in favour of six weeks of WBV training.
Researchers wrote that although the majority of studies showed favourable effects following WBV therapy, there were also inconsistencies that they did not like. For example different strength measures were used in different studies (5 minute sit to stand, 30 second sit to stand, isometric testing, dynamometry testing). Regardless, all the results indicated that WBV with or without exercise training has positive effects of the lower extremity muscle strength of people with T2DM.
They also criticized the user of various balance assessments (Wii balance board, the Berg Balance Scale, the functional reach test (FRT), and the single leg stance test. Most studies again reported positive results in favour of WBV training except the study by Kordi Yoosefinejad et al. which reported no significant difference between WBV and control groups.
Comments: It is important to note, however that in the Yoosefinejad study, they used a low intensity of vibration (30 Hz at 2 mm of displacement), exercised only twice per week, and applied only 30 seconds of exercise to begin with and only progressed to one minute of training exercise by the 5th and 6th weeks therefore the overall intensity required for muscular adaptation was likely far too low. Despite the low intensity of exercise used in the Yoosefinejad study, they actually concluded that strength still increased and the timed up and go test decreased significantly in the WBV training group. There is no explanation as to why the authors Zhang et al. reported negative findings of this study.
Finally these researchers noted that they excluded non-english studies that may have added more to the conversation. In conclusion they found WBV trying to be a “novel, effective, safe and alternative approach”, however more studies are needed to take into consideration individuals with diabetic neuropathy and differences in vibration parameters. Their overall rating at the end of the study is that WBV training for T2DM is still inconclusive with more studies needed.
In this review, Zhang et al. also omitted all studies that considered the effects of WBV training on glycemic control or insulin sensitivity. For more information on this please see the recent meta-analysis from the Brazilian Journal of Physical Therapy, 2016; 20(1):4-14, and the 2017 study form the Al Ameen Journal of Medical Science, 2017; 10(1):3-9.
The effects of whole body vibration in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials
Journal: Brazilian Journal of Physical Therapy, 2016; 20(1):4-14
Study Context: These researchers sought to carry out a systematic review of the effects of WBV training on the glycemic control, cardiovascular risk factors, and physical and functional capacity of patients with T2DM.
Out of 585 potentially eligible articles, two studies were considered eligible . WBV interventions provided significant reduction of 12 hour fasting blood glucose (A reduction of 25.7 ml/dl). Improvements in glycated hemoglobin, cardiovascular risk factors and physical and functional capacity were found at 12 weeks of WBV training. No adverse effects were reported in any of the studies.
After 12 weeks of upper and lower body exercises performed on the vibrating platform, a significant decrease (p<0.05) was found in cholesterol, triglycerides, atherogenic index, weight, waist circumference, waist to hip ratio and body fat percentages compared to the control group. Improvements (p<0.05) were found in the 6 minute walk test distance and the 30 second sit to stand test. Static balance shoed a decrease in centre of pressure excursion with eyes closed (feet apart and together) The conclusions of this study is that WBV combined with exercise seems to improve glycemic control in patients with T2DM in an exposure dependent way (ie 12 weeks of training required) Comments: This is a rigorous study that resulted in the exclusion of most the research papers gathered. The two that were chosen both used extremely low intensity WBV exercise of 1-2 total g forces, typically achieved with high frequency and low amplitude training. This type of training is far lower in terms of intensity of many forms of WBV training that provide up to 12 g and even up to 20 g forces during the exercise session.
The improvement in eyes closed balance is an interesting finding that suggests but does not prove that WBV training likely has a role in proprioception as well as strength.
Short-term effects of the whole body vibration on the balance and muscle strength of type 2 diabetic patients with peripheral neuropathy: a quasi-randomized controlled study
Journal: Journal of Diabetes and Metabolic Disorders, 2015; 14:45
Study Context: The aim of this study was to assess the effects of Whole Body Vibration (WBV) on the strength and balance of patients with type 2 diabetes.
Subjects were randomly assigned to a WBV exercise or control group. The WBV group received exercise (30 Hz, 2 mm) twice per week for 6 weeks.
After 6 weeks, the WBV group significantly improved strength in their shin and quadriceps muscles and significantly improved their time in the Timed Up and Go test
Comments: This study is interesting in that the exercise performed during the 6 week trial was in fact very low. Subjects held a 30 degree squat position for 30 seconds for the first two weeks; 45 seconds for the third and fourth weeks; and 60 seconds for the final two weeks. All were barefoot and did not use any balance aid during the exercise period.
Journal: Archives of Physical Medicine and Rehabilitation, 2014, 95: 439-46
Study Context: Exercise interventions are now recognized as a useful strategy to improve balance as well as mobility and muscle strength and ti enhance functional independence in long term survivors of stroke. Since Whole Body Vibration is considered a neuromuscular training method it was hypothesized that it might a useful multi-dimensional approach to counter several impairments with stroke.
Fifteen adults with chronic stroke (stroke more than 6 months ago) were randomly assigned to a Whole Body Vibration training or control group. The vibration exercise group did a variety of static and dynamic squat exercises on a platform with vibration amplitudes of 1.7 and 2.5 mm and frequencies of 35 and 40 Hz. The control group patients continued with their normal activities. The WBV trading group performed exercises 3 times per week for 6 weeks that included standing on the toes, high squats, deep squats, wide stance squats and single leg squats. Vibration intensity was slowly raised by increasing the frequency from 35 to 40 Hz or by increasing the amplitude from 1.7 to 2.5 mm, or both. Exercise intensity was increased by progressing the time of the hold position from 30 seconds to 1 minute and by increasing the number of sets.
After 6 weeks of training all patients had completed their training and there were no adverse effects from the training. The training group had increased knee extension strength (isometric and isokinetic at 2400/sec. Postural control also improved in the vibration training group.
Comments: This is a preliminary study of small sample size. The researchers conclude that WBV training might be a safe and feasible way to improve some aspects of lower limb strength and postural control in adults with chronic stroke.
Impact of Whole Body Vibration training on balance and muscle power in patients with severe COPD - a randomized controlled trial
Journal: European Respiratory Journal, 2016, 48(60)
Study Context: There are several studies that show the benefits to vibration training for people with chronic obstructive pulmonary disease (COPD). This study sought to investigate potential mechanisms of these beneficial effects.
Fifty patients were recruited during a 3 week hospital program. Groups were randomly selected to participate in either a Whole Body Vibration Training (WBVT) regime or to a group that performed the same exercises without vibration. Researchers assessed balance (Romberg stand, tandem stand, 1-leg stand with eyes open and closed) and muscle power (2 leg jump, 5 repetition sit to stand and a 1 minute sit to stand test)
After the rehabilitation program, the WBVT group improved balance significantly more than the control group in 2 out of 4 domains (tandem stand +10% and 1 leg stand +6%) and significantly improved some measures of muscle power (jump height +26%, 5 second sit to stand -5.2 seconds)
They concluded that neuromuscular adaptations such as improved balance and muscle power may explain the positive effects of vibration training for individuals with COPD.
Comments: This study was only 3 weeks long. Exercise science suggests that these performance gains are probably mostly neuromuscular since muscle cell adaptations will probably take 6 weeks or more to occur. This would be an interesting study design to repeat over a longer period.
Post – Op Knee Rehabilitation
Whole Body Vibration Exercise Protocol versus a Standard Exercise Protocol after ACL Reconstruction: A Clinical Randomized Controlled Trial with Short Term Follow-Up
Journal: Journal of Sports Science and Medicine, 2014, 13: 580-589
Study Context: Forty (40) patients who underwent identical anterior cruciate ligament (ACL) reconstruction surgeries were randomized to a group receiving standard rehabilitation exercises or Whole Body Vibration (WBV) exercise training.
The standard care group performed 80 minutes of exercise per session and included: a warm-up stretches and balance exercises.
The WBV exercise group began with 15 minutes of light warm-up on an exercise cycle. From weeks 2 to 4 Post-op, the WBV exercise group then performed 2 – 6 repetitions of 1 minute each.
Comments: This study used a pivotal style WBV machine. The training group began at 10-15 Hz and progressed by 5 Hz per session up to 30 Hz.
The Effect of early Whole-Body Vibration Therapy on Neuromuscular Control After Anterior Cruciate Ligament Reconstruction: A randomized controlled trial
Journal: The American Journal of Sports Medicine, Vol 41(4):804-814
Study Context: Despite rehabilitation training, defense in knee joint position sense, muscular performance, postural control and functional ability is common after anterior cruciate ligament reconstruction (ACLR) surgery. Previous research proved benefits when initiated from 3 months post-operatively but the effects of earlier WBV training unknown.
This study randomly assigned ACLR patients to either a treatment group or a reference group. The reference group received conventional knee rehabilitation while the treatment group received 8 weeks of WBV training in addition to conventional rehabilitation, starting at 1 month post-operatively.
Joint position sense, postural control, knee strength performance, and functional ability were assessed before surgery and at 1, 3 and 6 months respectively.
There were no complications throughout the study. All patients achieved full knee range of motion and stable knee joints at 6 months post-op.
The WBV training group demonstrated significantly better postural control, muscle performance, single legged hop and shuttle run, but no significant difference in joint position sense, triple hop or carioca.
Early WBV training started from 1 month post-op was an effective training method without compromising range of motion or stability.
Vibration training in this study began at 35 Hz and progressed to 40, 45 and 50 Hz as the study progressed with an amplitude of 4 mm. This was based on previous research which showed that these higher frequencies at 4 mm amplitude resulted in the greatest knee extensor activity.
Three different exercise positions were used: high squat, low squat and single leg squat. These exercises were chosen because of previous research that demonstrated increased electrical muscle activity ranging from 49% to 365% during exercise in these positions on a vibration platform. A total of 319 minutes of vibration training was performed in this study.
Comments: Researchers concluded that whole body vibration training should begin at 1 month post-op ACLR. They also suggest future studies that apply additional vibration training exercises to the rehabilitation program.
Balance and Fall Prevention
Influence of Whole-Body Vibration Training Without Visual Feedback on Balance and Lower Extremity Muscle Strength of the Elderly
Journal: Medicine (Baltimore), 2016 Feb;95(5):e2709
Study Context: Balance deficit is one of the leading causes of falls in older adults. Aging induces the gradual decline of sensory functions, central processing, musculoskeletal and motor control, and neural pathways, thus leading to poor postural stability. Previous studies have also found that poor vision, restricted vision and declining depth perception are also closely related to body postural control.
This study randomly placed participants into one of three groups:
Group 1 performed a squat exercise on a vibration platform oscillating at 20 Hz with 4 mm displacement.
Group 2 performed the same squat exercise with the same parameters except they were blindfolded (visual feedback deprived).
Group 3 was the control group and they performed the same squat exercise except without any vibration and with the eyes open.
All three groups exercised for 5 minutes at a time, 3 times per week for 3 months.
Participants were retested at the end of the 3 month trial and again at 6 months. Testers were blind to the grouping of each subject.
Balance performance improved in both vibration training groups at 3 and 6 months compared to control and was significantly better again in the visual deprived group (blindfolded vibration training).
Strength performance remained the same in the control group. In the blindfolded vibration training group, knee extensor strength increased 37.89% and knee flexor strength improved 19.4%. In the eyes open vibration training group only knee extensor strength increased (15.4%).
At the 6 month follow-up, 0% of the eyes open vibration training group, 0% of the eyes closed vibration training group reported falls, and 28.57% of subjects from the control group reported hospital visits due to falls. (The average fall rate in adults over 65 is around 30%)
Comments: Previous studies have shown vibration training to improve strength and balance in older adults. Eliminating visual feedback, however, significantly improved both strength and balance performance during vibration training even more that vibration training with eyes open.
This suggests that we can utilize eyes closed vibration training for people whose goals include increased leg strength, balance and falls prevention.