Embed Size (px)
Citation preview
Archives of Gerontology and Geriatrics 59 (2014) 305–311
Effect of stochastic resonance whole body vibration on functionalperformance in the frail elderly: A pilot study
Jessica Kessler, Lorenz Radlinger, Heiner Baur, Slavko Rogan *
Bern University of Applied Sciences, Discipline Physiotherapy, Bern, Switzerland
A R T I C L E I N F O
Article history:
Received 24 December 2013
Received in revised form 13 June 2014
Accepted 20 June 2014
Available online 9 July 2014
Keywords:
Short physical performance battery
Isometric maximum voluntary contraction
Isometric rate of force development
A B S T R A C T
The aim of this pilot study was to evaluate the feasibility and the effect size of a four-week stochastic
resonance whole body vibration (SR-WBV) intervention on functional performance and strength in frail
elderly individuals. Twenty-seven participants have been recruited and randomly distributed in an
intervention group (IG) and a sham group (SG). Primary outcomes were feasibility objectives like
recruitment, compliance and safety. Secondary outcomes were short physical performance battery
(SPPB), isometric maximum voluntary contraction (IMVC) and isometric rate of force development
(IRFD). The intervention was feasible and safe. Furthermore it showed significant effects (p = 0.035) and
medium effect size (0.43) within the IG in SPPB. SR-WBV training over four weeks with frail elderly
individuals is a safe intervention method. The compliance was good and SR-WBV intervention seems to
improve functional performance. Further research over a longer time frame for the strength
measurements (IMVC and IRFD) is needed to detect potential intervention effects in the force
measurements as well. Clinical Trial register: NTC01704976.
� 2014 Elsevier Ireland Ltd. All rights reserved.
Contents lists available at ScienceDirect
Archives of Gerontology and Geriatrics
jo ur n al ho mep ag e: www .e lsev ier . c om / lo cate /ar c hg er
1. Introduction
Aging is associated with a decline in functional performance.This includes loss of muscle strength, muscle mass, and physicalcapacity (Doherty, 2001; Doherty, Vandervoort, Taylor, & Brown,1993; Rogers & Evans, 1993). In the literature this process isdefined as sarcopenia (Rosenberg, 1997) or dynapenia (Manini &Clark, 2012). Manini and Clark (2012) characterize sarcopenia asthe loss of muscle mass, whereas dynapenia is described as the lossof muscle mass and muscle strength. The loss of muscle strength isalso accompanied by the loss of number and recruitment of motorunits (Doherty et al., 1993), decreased physical activity (Amigueset al., 2013) and contractile quality (Manini & Clark, 2012).
Manini and Clark (2012) stated age-related loss of muscle massis weakly associated with the loss of muscle strength, becausefunctional performance of the muscular skeletal system isdependent on other factors than muscle mass alone. The loss ofmuscle strength and functional capacity leads to the loss of musclefunction and results in frailty and increased risk of falling (Clarket al., 2013; de Vries, Peeters, Lips, & Deeg, 2013).
* Corresponding author at: BUAS, Slavko Rogan Lindenrain 4, 3010 Bern,
Switzerland. Tel.: +41 31 848 35 36; fax: +41 31 848 35 21.
E-mail address: [email protected] (S. Rogan).
http://dx.doi.org/10.1016/j.archger.2014.06.005
0167-4943/� 2014 Elsevier Ireland Ltd. All rights reserved.
Sensorimotor and strength exercises are known as interventionmethods to increase muscle strength and to prevent falls in elderlyindividuals (Granacher, Gollhofer, Hortobagyi, Kressig, & Muehl-bauer, 2013). Skelton and Dinan (1999) developed a fallsmanagement exercise program (FaME) which divides the trainingstructure in three parts: first, ‘‘skilling up’’, second, ‘‘training thegain’’ and third, ‘‘maintaining the gain’’. The first phase starts withthe aim ‘‘to improve neuromuscular function, technique and safetyduring exercise’’ (Skelton & Dinan, 1999). The two following partsaim at further developing the training effects of the previous part.The final purpose is to keep the learned skills and to progressivelyraise intensity and load of the training step by step from one part tothe next. The considerations of the FaMe are about to be added tothe new classification Physical Performance Classification forElderly (PPCfE). This classification makes it possible to distinguishbetween pre-frail and frail, mobile and trained elderly (Rogan & deBruin, 2013; Rogan, Schmidtbleicher, & Radlinger, 2014).
Evidence is still lacking for what kind of exercise is mostsuitable and effective for frail elderly individuals (Rogan, Hilfiker,Schmid, & Radlinger, 2012; Rogan, Radlinger, et al., 2012). Frailelderly individuals with severe physical limitations who want tostart a training program are advised to first complete a ‘‘skillingup’’ prior to the implementation of more traditional forms ofexercise (Rogan, Hilfiker, et al., 2012; Rogan, Radlinger, et al.,2012).
J. Kessler et al. / Archives of Gerontology and Geriatrics 59 (2014) 305–311306
One possibility for skilling up could be stochastic resonancewhole-body vibration (SR-WBV). A stochastic resonance dynamichas been applied in a variety of neurophysiological and perceptualsystems (Collins, Imhoff, & Grigg, 1996) and human musclespindles (Cordo et al., 1996). SR-WBV has the characteristic ofexecuting a lot of small impulses (vibrations) on the body in a shortperiod of time, in contrast to sinusoidal WBV (S-WBV). Further-more the vibration is random, which means that the direction ofthe vibrations and the force load are not predictable, and the bodywill be constantly challenged to adapt to the muscle reactions. Thiskind of stimulus triggering muscle spindles can improve thefunctionality of the nerve-muscle system (Rogan, Hilfiker, et al.,2012), even more than other conventional S-WBV. An additionaladvantage is that the subjects stand on two separate platforms thatoscillate independently during SR-WBV while the subjects standwith two feet on a single S-WBV platform.
Due to its simplicity, the SR-WBV device seems to beconvenient for frail elderly individuals. Since it is known as aform of exercise with only low impact on the cardiovascularsystem (Herren, Hangartner, Oberli, & Radlinger, 2009), it alsoseems suitable for elderly individuals with mild vascularpathology. Following this rationale, one can assume that it ispossible to stimulate the neuromuscular systems by applying SR-WBV. SR-WBV could be used for sensorimotor training in frailelderly individuals in the context of skilling up, since they mightnot be prepared for an exposure to the load and long trainingsessions normally applied in regular training routines (Rogan,Radlinger, et al., 2012).
It seems justified in this context to perform a pilot study and toassess the feasibility of applying SR-WBV in frail elderlyindividuals, because no study investigating the effects onfunctional performance or strength of SR-WBV training in frailelderly individuals has been published so far. The findings of such astudy may give important information about feasibility beforeconducting a larger trial (Thabane et al., 2010).
Assessed for e
Analysed (n = 13)
Allocated to intervention (n = 14)
♦ Received allocated intervention (n = 13)
♦ drop out: death (n = 1)
Allocati
Analys
Randomiz
Enrollm
Fig. 1. Flow diagra
The aim of this pilot study was to evaluate the feasibility of theintervention process and assess the implication of four weeks ofSR-WBV training on physical performance, isometric maximalvoluntary contraction (IMVC) and rate of force development (IRFD)in frail elderly individuals.
2. Methods
2.1. Design
This is a randomized controlled pilot study with blinded frailelderly individuals, randomly divided into an intervention group(IG) and a sham group (SG) and non-blinded supervisors. It followsthe publication guideline of Thabane et al. (2010), which states thatthe main goal of a pilot study is to assess feasibility and to avoidfailure of a large study (Fig. 1).
2.2. Participants
From August to October 2012, 27 frail elderly individuals wererecruited in a retirement home in Switzerland (Table 1). In thispilot study (pre-)frail was defined using the Physical PerformanceClassification for Elderly (PPCfE) proposed by Rogan et al. (2014).The PPCfE was determined by the total score of the short physicalperformance battery (SPPB). Status pre-frail & frail: 0–6 points;status mobile: 7–10 points; status trained: 11–12 points. Pre-frail& frail were defined if �6 points was confirmed. The followinginclusion criteria had to be fulfilled: aged over 65 years, able tostand with or without aids, a score of at least 16 points in the minimental test (MMT) and a score of <6 points in the SPPB.
The following exclusion criteria were determined: severe, non-adjusted visual disorders (e.g. diplopic images), thrombosis, recentfractures, infections, acute inflammation, tissue damage or recentoperation scars, amputation appliance on the thigh or lower leg,
ligibility (n = 27)
Analysed (n = 11)
♦ Excluded from analysis because < 11
trainingsession(n = 2)
Allocated to rest (n=13)
♦ Received allocated intervention (n = 13)
on
is
ed (n = 27)
ent
m pilot study.
Table 1Socio-demographic and anthropometric characteristics of the participants as well
as their baseline measurements (mean � SD).
Characteristics Intervention group
(n = 13)
Sham group (n = 11) p
Age, years 90.7 (�7.5) 83.8 (�9.3) 0.077
Weight, kg 68.6 (�15.2) 68.2 (�22.2) 0.368
Height, m 1.63 (�0.11) 1.58 (�0.14) 0.977
BMI, kg/m2 25.9 (�4.9) 27.0 (�7.6) 0.706
Individuals
using aids (%)
100 100 1.0
Male/female, n 5/8 3/8 0.562
J. Kessler et al. / Archives of Gerontology and Geriatrics 59 (2014) 305–311 307
acute joint diseases, activated arthritis, acute rheumatoid arthritisof the lower limb, acute back pain, severe migraine and epilepsy.
2.3. Randomization
An independent research assistant performed randomization,using a random Microsoft Excel 2010 table. The participants wererandomly assigned to either an SR-WBV IG or an SG by means ofsealed opaque envelopes that were distributed after the comple-tion of all baseline assessments.
Prior to the start of the intervention, written informed consentwas obtained from all participants. Permission from the BernEthics Commission was requested and received (No. 147/12). Thestudy protocol was registered at the clinical trial register of the U.S.National Institute of Health (NCT01704976).
2.4. Intervention protocol
The intervention parameters of this study were based on aprevious protocol of an unpublished pilot study by Rogan,Radlinger, Schmdtbleicher, de Bie, & de Bruin (2011) withuntrained elderly individuals. It is known from this unpublishedstudy (clinical trial register: NCT01543243) that the recruitmentrate and compliance rate is not very good with frail elderlyindividuals [Application of SR-WBV in frail elderly: the effect onpostural control – a pilot study (Clinical Trial register:NCT01543243)]. Based on this experience, the motivationalvolitions model (MoVo model) was applied (Fuchs, Goehner, &Seelig, 2011; Gollwitzer, 1999; Milne, Orbell, & Sheeran, 2002) forfrail elderly individuals. This involves overcoming feelings ofdispleasure or other action barriers by a volitional, targeted controlof thoughts, motives, emotions and actions to achieve these goals(Kehr, 2004). The term ‘‘motivation’’ describes only the pursuit ofgoals or results. Only if volition is added, are objectives and resultsachieved.
All participants were familiarized with the SR-WBV device oneweek prior to the intervention period. Their standing position waswith slightly bent hip, knees and ankle joints and without shoes.They were also allowed to hold onto the bars on both sides, ifrequired.
The intervention was carried out on the SR-WBV device calledZeptor med1 plus Noise (Frey AG, Zurich, Switzerland). Thefrequency can be varied between limits 1 Hz and 12 Hz. A specialseat was constructed for the participants to sit down during the 1-min break. The intervention took place on three days a week, over aperiod of four weeks. Each intervention consisted of five 1-minvibration periods with a 1-min break between each set. The IGvibrated with a basic frequency of 3 Hz and noise level 4. To reachprogressive exertion, the basic frequency was increased to 6 Hz,depending on possibilities of the individual concerned. Theamplitude range was 3 mm and did not change. The augmentationof the exercise intensity was carried out with soft terms ofreference: if the participants were able to stand parallel without
holding onto the bars, the vibration frequency was increased by1 Hz. If they reached 6 Hz, the original parallel standing positionwas made more difficult, starting with tandem standing up to slowdynamic functional squat movements, always with one foot oneach footplate and with the same augmentation criteria as above.Ahlborg, Andersson, and Julin (2006) applied an analog procedurein their study. The SG vibrated with a basic frequency of 1 Hz andnoise level 1 with no increase of the basic frequency and noadditional exercises. Rogan, Hilfiker, et al. (2012) and Rogan,Radlinger, et al. (2012) conducted a trial where they showed thatSR-WBV training with 1 Hz and Noise level 1 has no effect andcould therefore be implemented as a valid sham intervention.
2.5. Primary outcome: criteria of success
Lancaster, Dodd, and Williamson (2004) state that pilot studiesplay an important role in health research to provide informationfor the planning and justification of randomized controlled trials.The primary goal of this pilot study was to investigate the criteriaof success of a four-week SR-WBV training program with frailelderly people. The criteria should be based on the primary focuson feasibility objectives, like resources, recruitment, compliance,safety and management regarding the SR-WBV intervention.
Resources: The goal was to analyze the availability of space forthe vibration device, material, time for the participants and staff.The following questions are required to be answered according toThabane et al. (2010): Where is the intervention going to takeplace? Is there enough space for the SR-WBV device? It wasplanned to place the SR-WBV device in the corridor of the ward.How much time does it take for one participant to conduct all themeasurements and the intervention? For each participant therewas an estimate of 45 min for the measurement and 15 min for theintervention. The staff of the institution were informed withpresentations and interviews prior to the intervention.
Recruitment: Is it possible to recruit enough participants for theintervention in a time frame of three months between August andOctober? A minimum of 20 participants was demanded for thisstudy.
Compliance: Each participant was requested to complete 12training units on the SR-WBV platform in four weeks. An attendancelist was kept to control the exercise sessions. The compliance ratewas calculated and determined at 85%. Out of the 12 training units, aminimum of 10 training sessions had to be completed. An adherencerate of 90% (from a total of 324 training sessions, 292 had to becompleted) was required. To enhance the motivation and thecompliance of the participants, the researcher interviewed everypotential participant independently using the MoVo model. Groupdiscussions before intervention and personal interviews before andduring intervention were used to keep people on track.
Safety: A safe exercise session had to be guaranteed. The maingoal was to evaluate pain, dizziness and other side effects. Asupervisor was always present during the intervention. Hisresponsibility was to detect if the participants suffered any sideeffects, using a questionnaire before, during and after theintervention.
2.6. Secondary outcomes
2.6.1. Short physical performance battery
The SPPB (Guralnik et al., 1994) is a test package used tomeasure physical performance. The SPPB shows high reliabilitywith an ICC of 0.88–0.92 (Ostir, Volpato, Fried, Chaves, & Guralnik,2002). It measures balance (stance, semi-tandem stance andtandem stance) and walking speed, and evaluates strength,balance, coordination and joint mobility of the lower limb withinfive sit-to-stand movements.
J. Kessler et al. / Archives of Gerontology and Geriatrics 59 (2014) 305–311308
The maximum score to reach was 12 points. The authorsdefined the following classification: SPPB score 0–6 points = weakperformance, SPPB score 7–10 points = mean performance, SPPBscore 11–12 points = good performance (Guralnik et al., 2000). Inthe present study, the authors used the SPPB value of �6 points, asa cut-off value for frail elderly individuals. The data was collectedat baseline and after the four-week intervention period.
2.6.2. Force measurement
IMVC and IRFD knee extension and knee flexion were measuredat baseline and after the four-week intervention period. The onsetof force was determined at 10N of each individual’s force-timecurve. IMVC in Newton (N) was determined as the maximum pointon the force-time curve. Submaximal force values (Fsub) werecalculated at 30, 50, 100 and 200 ms relative to the onset of force.IRFDmax was defined as the maximal slope of the force–time curvebetween onset of force and 200 ms (N/s). Submaximal IRFD values(IRFDsub) were calculated as the mean slope of the force-timecurve (DF/Dt) over time intervals of 0–30, 0–50, 0–100 and 100–200 ms relative to the onset of force (Gruber & Gollhofer, 2004).
A dynamometer (Sensor KM 1500S Megatron Munich,Germany) was used to measure the force values. The participantssat on a chair with 908 knee flexion and the dynamometers werefixed above the right (r) and left (l) ankle joint. On the command ‘‘3-2-1-go!’’ the participants had to flex (flex) or extend (ex) each legseparately for 5 s as fast and as strongly as possible against thefixation. The analog signal of the dynamometer was transmitted toa measurement amplifier (UMV, uk-labs, Kempen, Germany),digitalzed by a 12-bit A-D converter (Meilhaus ME-2600i, SisNovaEngineering, Zug, Switzerland) with a sampling rate of 1 kHz andanalyzed with the Analog Digital Signal processing software (ADS,uk-labs, Kempen, Germany).
2.6.3. Data processing
Prior to the data extraction, the force signal was low-passfiltered (10 Hz, Butterworth characteristic, filter steepness 24 dB/oct, half bandwidth �2.4 Hz).
2.7. Statistical analysis
Due to the fact that this is a pilot study and that number ofparticipants is low, statistical analysis was not the main focus(Thabane et al., 2010). Therefore, non-parametric analysis proce-dures were applied. SPSS 20 for Windows (SPSS, Inc; Chicago, IL)was used to calculate between and within group effects. For thedependent samples (within groups: before and after intervention)the Wilcoxon signed-rank test was used. For the independentsamples (between groups) the Mann–Whitney U test was applied.The level of significance was set at p < 0.1 (Thabane et al., 2010). Allvalues were reported as median and interquartile range (IQR). Inaddition, the rate of participants’ adherence to the treatmentprotocol was calculated in % using the following formula: the totalof effectively carried out sessions � 100 divided by the total ofpossible SR-WBV vibration sessions. A further aim was to calculate
Table 2SPPB values in median and IQR.
Variable Time IG (n = 13) Wilcoxon
P
ES
SPPB Pre 3 (2–4.5) 0.001a
Post 6 (3.5–7.5) 0.89
P, p-value.a Wilcoxon pre-post-test.b Mann–Withney-U post-test IG-SG.
post-training effect sizes (ES) for the differences within andbetween the groups expressed as r = Z/HN. For r, an effect size of0.1 is considered a ‘small’ effect, around 0.3 a ‘medium’ effect and0.5 and above a ‘large’ effect (Corder & Foreman, 2009).
3. Results
3.1. Primary outcomes
Resources: The SR-WBV sessions were conducted on thecorridor of the ward in a retirement home. The SR-WBV needsabout 2 m2 of space. The ward where the intervention took placeoffered enough space to place the device and conduct the SR-WBVinterventions. Furthermore, the vibration device did not hinder theeveryday working life of the staff on the ward. The time frame of9 min per intervention session did not cause particular trouble forthe participants, because they were allowed to briefly hold ontothe bars if required and to sit down on the special seat during everyvibration break. The supervision of the interventions, including thesupervision of the way to the intervention apparatus, took about20–30 min for each participant. To conduct the measurements,more than 1 h was needed for each participant, which neededalmost a week to complete the entire 27 measurements. Due to theinstruction of staff prior to the intervention, they were verycooperative and helped whenever possible to keep the participantsready for the planned intervention time.
Recruitment: The goal was to recruit 20 participants, but 27participants were able to be recruited. 36 candidates met theinclusion criteria, 27 of whom were motivated and recruited for thetraining. One person who had been included died before the start ofthe intervention. The remaining residents were not eligible becauseof neurological diseases or dementia or fractures of the lower limb.
Compliance: 22 of the 27 participants completed all 12 trainingunits. Two participants completed 11 training units and were alsoincluded in the evaluation. So 24 participants overall wereincluded in the evaluation. Three of the 27 participants fulfilledless than ten training units, two due to illness and one of thembecause of death. A total of 324 training sessions would have beenpossible. Out of that, the participants completed a total of 293training sessions. As a result of this, an adherence rate of 90.4% hasbeen calculated.
Safety: No notable side effects were observed during the SR-WBV session.
3.2. Secondary outcomes
Comparison of socio-demographic and anthropometric char-acteristics and baseline values of the two groups showed nosignificant differences (Table 1).
SPPB: The SPPB (Table 2) shows a significantly higher score andmedium ES (r = 0.43) after the four-week training session in the IGcompared to the SG (p = 0.035). The within-group comparison ofthe IG showed significant changes (p = 0.001) and large ES
SG (n = 11) Wilcoxon
P
ES
Mann–Whitney-U
P
ES
4 (2–6) 0.102 0.035b
4 (2–4) 0.5 0.43
J. Kessler et al. / Archives of Gerontology and Geriatrics 59 (2014) 305–311 309
(r = 0.89). In the SG no significant changes in the within-groupcomparison could be found (p = 0.102) but also large ES (r = 0.50).
For the force values no significant effects within groups andbetween the groups were determined after four weeks of SR-WBVintervention.
IMVC: No changes were determined.Fsub: significant results and medium-to-large ES after the SR-
WBV intervention in the IG in the following force values: left legextension at 30 ms (p = 0.087; r = 0.48), at 200 ms (p = 0.1;r = 0.46), and right flexion at 30 ms (p = 0.059; r = .52), at 50 ms(p = 0.087; r = 0.48), and 100 ms (p = 0.06; r = 0.52).
IRFD: IRFDmax indicates a significant result and large ES in theleft extension (p = 0.064; r = 0.51) of the within-group comparisonof the IG.
IRFDsub: in the IG, significant results and large ES emerge aftertraining in the within-group comparison in the following RFDvalues: right leg flexion from 0 to 30 ms (p = 0.055; r = 0.53), from 0to 50 ms (p = 0.064; r = 0 .51), and from 0 to 100 ms (p = 0.064;r = 0.51).
4. Discussion
The aim of this pilot study was to evaluate the feasibility of theintervention process and assess the impact of a four-week SR-WBVintervention on physical performance, IMVC and IRFD in frailelderly individuals. The data from this pilot study provide usefulinformation concerning the feasibility, the safety and the effects ofa four-week SR-WBV intervention in the frail elderly population.This pilot study was feasible, but with modifications. Thesemodifications are discussed below.
4.1. Primary outcomes: criteria of success
The goals for the resources have mostly been reached. TheZeptor med1 plus noise is a device which does not need muchspace, only about 2 m2. It can be placed in a corner and is ready tostart the exercise session in 1 min. Retirement-home staffs wereable to pass the SR-WBV device with residents or the food trolleywithout any problems. Their daily operations were not disrupted.The device is easy to operate and offers a good possibility for use infurther studies. Therefore it was no problem to conduct theintervention sessions in the corridor of the ward.
Due to the high mean age of 87.3 (�8.4) of the participants it isimportant to continually repeat the information on the measurementday. For this information session it may be necessary to schedulemore time, not only once a week prior to the intervention. In this way,participants can be familiarized with the movement they have toexecute. It is essential that the participants know what they have todo in order to avoid learning effects and other cognition based bias.Not only the fact that each participant had to be measured four timesbut also their mental state required repetitive explanations that mademeasurements more time consuming than initially expected.
Before the recruitment and the intervention started, there werepresentations to inform the staff at the retirement home. Thenurses, physiotherapists, the technical services, doctors and themanagement of the institution were informed. With the support ofthe employees of the institution and the MoVo model (Fuchs et al.,2011), the target to recruit 20 participants has been reached. In therequired time frame of three months, 27 out of 36 participantswere able to be recruited. In the present study a personal interviewwas adopted to motivate and enhance the participants’ volition forthe training. This method seemed to be very suitable becausecontact with the participants was kept close and any sign of loss ofmotivation could be recognized and reacted to. This way of contactand interviews seems to be an adequate mode for the frail elderlyparticipants, and it was possible to recruit the desired number. The
attrition rate was less than 10% and did therefore meet therequired figure.
To recruit the individuals, the form of a personal motivationalinterview seems to be suitable. Fuchs et al. (2011) state that thepersonal motivation for training can be enhanced by talking to theperson independently and trying to express the personal goals andconcerns.
The compliance rate in this current pilot study was good. Out ofthe 27 included participants, 24 completed the interventionsession. Prior to the training sessions, each participant was fetchedfrom their room. In this way, personal contact with the participantscould be maintained and the MoVo model could be applied further.Because of the fact that this personal assistance took place, theattrition rate could be kept low. At 90.4%, the adherence rate in thispilot study was relatively high. This is far more than the ratesreported in the systematic review of Nyman and Victor (2012).Therefore, the data of this present study should be replicated in afurther four-week intervention study.
One reason for not being able to complete all 12 trainingsessions was a wave of influenza that affected the institution at thetime of the intervention. One person suffered temporarily withheart problems and was not able to train in a regular way andtherefore missed one training session. Because of the decreasedimmunity (Goodwin, 1995), the risk of contracting influenza oranother illness is heightened in old age.
None of the participants complained about any side effects ofthe SR-WBV intervention. This finding coincides with thestatements of Herren and Radlinger (2011), who investigatedthe risks and side effects of WBV training. The sessions are safe andnot dangerous since a supervisor coordinated every session.
4.2. Secondary outcomes
Feasibility studies should not be overrated but analyzed andinterpreted with caution (Bauhofer et al., 2001; Rogan, Radlinger,Portner-Burkhalter, Sommer, & Schmdtbleicher, 2013). Summa-rizing the effect after SR-WBV intervention of this feasibility study,only provides first estimates for the chosen outcome measures.This study indicates that the 12 SR-WBV intervention sessionsshow large ES, statistically significant results in SPPB andimprovement in Fsub, IRFDmax and IRFDsub. For IMVC nostatistically significant difference was determined.
Rehn, Lidstrom, Skoglund, and Lindstrom (2007) concluded intheir review that there is strong to moderate evidence that long-term S-WBV can have positive effects on muscular leg perfor-mance. The strongest effect was observed with untrained andelderly people. Several findings in this pilot study support thisstatement. Large studies often last more than four weeks to detecteffects or have a higher number of participants. This pilot studywas kept small and well arranged, because the focus was on thefeasibility and not on the significance of the results. However, theIG shows a significant result (p = 0.035) in the SPPB with a mediumES compared to the SG after the SR-WBV intervention. In thewithin-group comparison, the IG shows significant effects with alarge ES. These results indicate that with four-week trainingprogram on the SR-WBV device, functional improvement canmainly be achieved when giving a progressive vibration input withintensities higher than 1 Hz.
To some extent there are significant improvements in thewithin-group comparison of the IG in single Fsub, IRFDmax andIRFDsub values before and after training, but small to large ES inthe majority of the data. What attracts attention here is the factthat all values of the right extension are not significant and showno effect. When considering the baseline data, one can detect thatall right leg data have a higher value in the baseline measurementthan the left leg. Based on that observation, one can state that the
J. Kessler et al. / Archives of Gerontology and Geriatrics 59 (2014) 305–311310
right leg is maybe the dominant one and is already in a moretrained state compared to the left leg (Newton et al., 2006).Therefore, it seems more difficult to reach a visible improvementwith 12 SR-WBV sessions in the dominant leg in extension.Frohlich, Links, and Pieter (2012) postulate that the moreuntrained someone is, the greater effect training can achieve.The muscle strength ratio of hamstrings to quadriceps should begenerally approximately around 0.66 with values from 0.43 to 0.90(Coombs, Garbutt, and Cramp, 2002). It appears that in theextension movement, one can generate more muscle strength thanin the flexion movement. Therefore, the weaker flexion movementhas a higher potential to increase. The findings can be interpretedas an adaptation of the neuromuscular system. It can be stated thatSR-WBV intervention has a positive effect in the fight againstdynapenia (Manini & Clark, 2012).
Furthermore, Machado, Garcia-Lopez, Gonzalez-Gallego, andGaratachea (2010) state that functional performance, as measuredby an increase of participants score in the TUG test, could beimproved with a S-WBV intervention over ten weeks. Gomez-Cabello et al. (2013) conducted a trial with S-WBV and detectedeffects on dynamic lower-body strength after an 11-weekintervention. Furness, Maschette, Lorenzen, Naughton, and Wil-liams (2010) showed that S-WBV improved functional perfor-mance (timed-and-up-and-go test and sit-to-stand-test) after 6weeks. All three studies investigated the effects after S-WBV inmobile (untrained) elderly individuals. The current study exam-ined effects in (pre)frail elderly.
Zhang et al. (2014) describe S-WBV as an effective method toimproving knee extensor strength after eight weeks in frail elderlypopulation.
After four weeks, Rogan, Hilfiker, et al. (2012) and Rogan,Radlinger, et al. (2012) determined an improvement in functionalstrength after SR-WBV intervention in mobile (untrained) elderlyindividuals. One can assume that S-WBV and SR-WBV have aneffect on the sensorimotor system and that this probably leads toan improvement of balance and strength (Haas, 2008). However,during SR-WBV intervention strength improvements are observ-able after four weeks. Among S-WBV participants, strengthimprovements are achieved after six weeks. SR-WBV participantsshowed a rapid force growth in an elderly population.
The SR-WBV is a device which provokes many short impulsesthat cause a response on the muscle spindles with stimulation of Ianerve-fiber afferents. This information facilitated the alpha motorneuron output and contraction of the extrafusal muscle fibers(Rogan, Hilfiker, et al., 2012). There is maybe a connection betweenthese statements and the findings in this pilot study.
Sitja-Rabert et al. (2012) detected an increase of isometric forcein their review. This current study determined no changes forIMVC. A cause why the IMVC shows no changes may be thatimprovements in maximum force are not expected after a four-week exercise period on an SR-WBV device (Wirth, Atzor, &Schmidtbleicher, 2007). It is rather the rate of force development(RFD) that is expected to change. Haas, Turbanski, Kaiser, andSchmidtbleicher (2004) postulate that SR-WBV has an influence onthe sensorimotor system and on the reflex activity of the muscle.One can assume that mainly the RFD, which is associated with theoutput of the recruitment ability of a muscle, should rise after anSR-WBV intervention. Maximum force may change at a later date,when the training is expanded in the ‘‘training gain’’ phase (Skelton& Dinan, 1999; Wirth et al., 2007).
4.3. Limitations
There are some limitations to be discussed. First, in this currentpilot study, the SPPB was used for inclusion criteria. A score of0–6 points is defined to be weak performance, 7–10 medium and
11–12 strong performance (Guralnik et al., 1994; Ostir et al., 2002).From this definition, the inclusion criteria have been defined. It hasto be discussed for a further study, if this is a reasonable way toinclude or exclude the potential participants. It would probably bea good alternative to integrate additionally to the SPPB, a gait speedtest like the expanded timed get-up-and-go (ETGUG) (Wall, Bell,Campbell, & Davis, 2000) to have one more specific criterion forinclusion and exclusion of the target frail elderly cohort.
Second, the age of the population in this present study wasvery high and this is associated with comorbidities. There werediseases during intervention, like influenza, that made it difficultto provide a continuous training cycle. Other difficulties werecaused by the decreasing cognitive function older people have todeal with. This is also the reason why it is reasonable to set a scoreof >16 in the MMT as an inclusion criterion. Especially in themeasurements procedure it was quite difficult for the partici-pants to realize what they were asked to do. Here, it should befavored to practice the measurement movement to familiarizethe participants with the setting and to improve the standardi-zation of the tasks.
Third, the reasons for two participants quitting the trainingwere fear and lack of motivation. For them, it would have beenhelpful to provide a longer introduction and preparation on the SR-WBV device prior to the start of the investigation. But this priortraining could have influenced the results afterwards. All otherparticipants were extremely motivated or could have been keptmotivated using the MoVo model (Fuchs et al., 2011).
Fourth, to have a more standardized intervention protocol. Theintervention augmentation of the IG should be standardized moreprecisely; for example the possible use of the bars during thevibration sequence.
5. Conclusion
This pilot study indicates that the study protocol is feasible andsafe for the frail elderly. Resources and compliance could bemanaged safely. The effects of the intervention on functionalcapacity parameters are shown in the significant results of theSPPB in the within-group comparison of the IG. For Fsub, IRFDmaxand IRFDsub there are trends of an improvement, which can beassociated with a positive influence on dynapenia. This appearsmainly in the effects of the IRFDmax and IRFDsub. Small-to-largeeffects are apparent in all variables. The assumption of the authorsis that it is not so important to calculate IMVC because it is notexpected to have effects after a time period of four weeks.Furthermore IRFD is to be preferred to IMVC because RFD is lostmore rapidly in older age than Fmax (Granacher & Gollhofer, 2005).Therefore RFD seems to be more essential in the fight againstdynapenia in old age.
The findings from the results allowed a sample-size calculationfor a larger study. The IRFDmax left extension test, for example,showed that the effect size of the intervention was moderate at0.31. For a further study with 80% power at a-level 0.05, anestimated sample size of 401 participants for a 2-group RCT-designwould be necessary.
Before conducting further research on this topic, it isrecommended that a reliability analysis of the force data of theforce measurement device be executed.
Conflict of interest
No conflict of interest.
Funding
No funding for this pilot study was required from any source.
J. Kessler et al. / Archives of Gerontology and Geriatrics 59 (2014) 305–311 311
References
Ahlborg, L., Andersson, C., & Julin, P. (2006). Whole-body vibration training comparedwith resistance training: Effect on spasticity, muscle strength and motorperformance in adults with cerebral palsy. Journal of Rehabilitation Medicine,38(5), 302–308. http://dx.doi.org/10.1080/16501970600680262. NR78P2MJ85G01250.
Amigues, I., Schott, A. M., Amine, M., Gelas-Dore, B., Veerabudun, K., Paillaud, E., et al.(2013). Low skeletal muscle mass and risk of functional decline in elderly com-munity-dwelling women: The prospective EPIDOS study. Journal of the AmericanMedical Directors Association, 14(5), 352–357. http://dx.doi.org/10.1016/j.jamda.2012.12.002
Bauhofer, A., Stinner, B., Plaul, U., Torossian, A., Middeke, M., Celik, I., et al. (2001).Quality of life and the McPeek recovery index as a new outcome concept for sepsistrials tested in a pilot study of granulocyte colony-stimulating factor in patientswith colorectal cancer. British Journal of Surgery, 88, 1147.
Clark, D. J., Pojednic, R. M., Reid, K. F., Patten, C., Pasha, E. P., Phillips, E. M., et al. (2013).Longitudinal decline of neuromuscular activation and power in healthy olderadults. Journals of Gerontology. Series A, Biological Sciences and Medical Sciences,68(11), 1419–1425. http://dx.doi.org/10.1093/gerona/glt036
Collins, J. J., Imhoff, T. T., & Grigg, P. (1996). Noise-enhanced tactile sensation. Nature,383(6603), 770. http://dx.doi.org/10.1038/383770 a0
Coombs, R., Garbutt, G., & Cramp, M. (2002). Comparison of conventional and func-tional hamstring-quadriceps moment ratios through a 90 degrees range of legmotion. Journal of Sports Sciences, 20(1), 3–4. http://dx.doi.org/10.1080/026404102317126137
Corder, G. W., & Foreman, D. I. (2009). Nonparameztric statistics for non-statisticans. Astep-by-step approach. Hoboken, New Jersey: John Wiley & Sons Inc.
Cordo, P., Inglis, J. T., Verschueren, S., Collins, J. J., Merfeld, D. M., Rosenblum, S., et al.(1996). Noise in human muscle spindles. Nature, 383(6603), 769–770. http://dx.doi.org/10.1038/383769 a0
de Vries, O. J., Peeters, G. M., Lips, P., & Deeg, D. J. (2013). Does frailty predict increasedrisk of falls and fractures? A prospective population-based study. OsteoporosisInternational, 24(9), 2397–2403. http://dx.doi.org/10.1007/s00198-013-2303-z
Doherty, T. J. (2001). The influence of aging and sex on skeletal muscle mass andstrength. Current Opinion in Clinical Nutrition and Metabolic Care, 4(6), 503–508.
Doherty, T. J., Vandervoort, A. A., Taylor, A. W., & Brown, W. F. (1993). Effects of motor unitlosses on strength in older men and women. J Appl Physiol (1985), 74(2), 868–874.
Frohlich, M., Links, L., & Pieter, A. (2012). Effekte des Krafttrainings – eine metaana-lytische Betrachtung. Schweizerische Zeitschrift fur Sportmedizin und Sporttrauma-tologie, 60(1), 14–20.
Fuchs, R., Goehner, W., & Seelig, H. (2011). Long-term effects of a psychological groupintervention on physical exercise and health: The MoVo concept. Journal of PhysicalActivity and Health, 8(6), 794–803.
Furness, T. P., Maschette, W. E., Lorenzen, C., Naughton, G. A., & Williams, M. D. (2010).Efficacy of a whole-body vibration intervention on functional performance ofcommunity-dwelling older adults. Journal of Alternative and Complementary Medi-cine, 16(7), 795–797. http://dx.doi.org/10.1089/acm.2009.0366
Gollwitzer, P. M. (1999). Implementation intentions: Strong effects of simple plans.American Psychologist, 54(7), 493–503.
Gomez-Cabello, A., Gonzalez-Aguero, A., Morales, S., Ara, I., Casajus, J. A., & Vicente-Rodriguez, G. (2013). Effects of a short-term whole body vibration intervention onbone mass and structure in elderly people. Journal of Science and Medicine in Sport.http://dx.doi.org/10.1016/j.jsams.2013.04.020
Goodwin, J. S. (1995). Decreased immunity and increased morbidity in the elderly.Nutrition Reviews, 53(4 Pt 2). S41–S44; discussion S44–S46.
Granacher, U., & Gollhofer, A. (2005). The impact of aging on explosive force productionand on postural reflexes. Deutsche Zeitschrift fur Sportmedizin, 56(3), 68–72.
Granacher, U., Gollhofer, A., Hortobagyi, T., Kressig, R. W., & Muehlbauer, T. (2013). Theimportance of trunk muscle strength for balance, functional performance, and fallprevention in seniors: A systematic review. Sports Medicine, 43(7), 627–641. http://dx.doi.org/10.1007/s40279-013-0041-51
Gruber, M., & Gollhofer, A. (2004). Impact of sensorimotor training on the rate of forcedevelopment and neural activation. European Journal of Applied Physiology, 92(1–2),98–105. http://dx.doi.org/10.1007/s00421-004-1080-y
Guralnik, J. M., Simonsick, E. M., Ferrucci, L., Glynn, R. J., Berkman, L. F., Blazer, D. G.,et al. (1994). A short physical performance battery assessing lower extremityfunction: Association with self-reported disability and prediction of mortality andnursing home admission. Journal of Gerontology, 49(2), M85–M94.
Guralnik, J. M., Ferrucci, L., Pieper, C. F., Leveille, S. G., Markides, K. S., Ostir, G. V., et al.(2000). Lower extremity function and subsequent disability: Consistency acrossstudies, predictive models, and value of gait speed alone compared with the shortphysical performance battery. Journals of Gerontology. Series A, Biological Sciencesand Medical Sciences, 55(4), M221–M231.
Haas, C. T. (2008). Vibrationstraining Biomechanische Stimulation und StochastischeResonanz Therapie. pt_Zeitschrift fur Physiotherapeuten, 7(60), 728–758.
Haas, C. T., Turbanski, S., Kaiser, I., & Schmidtbleicher, D. (2004). Biomechanical andphysiological effects of oscillating mechanical stimuli in humans. Deutsche Zeits-chrift fur Sportmedizin, 55(2), 34–43.
Herren, K., & Radlinger, L. (2011). Risks and side-effects of whole body vibrationtraining. Paper presented at the World Confederation of Physical Therapy Congress,Amsterdam.
Herren, K., Hangartner, C., Oberli, A., & Radlinger, L. (2009). Cardiovascular andmetabolic strain during stochastic resonance therapy in stroke patients.Physioscience, 5, 13–17.
Kehr, H. M. (2004). Implicit/explicit motive discrepancies and volitional depletionamong managers. Personality and Social Psychology Bulletin, 30(3), 315–327. http://dx.doi.org/10.1177/0146167203256967
Lancaster, G. A., Dodd, S., & Williamson, P. R. (2004). Design and analysis of pilotstudies: Recommendations for good practice. Journal of Evaluation in ClinicalPractice, 10(2), 307–312. http://dx.doi.org/10.1111/j.2002.384.doc.x
Machado, A., Garcia-Lopez, D., Gonzalez-Gallego, J., & Garatachea, N. (2010). Whole-body vibration training increases muscle strength and mass in older women:A randomized-controlled trial. Scandinavian Journal of Medicine and Science inSports, 20(2), 200–207. http://dx.doi.org/10.1111/j.1600-0838.2009.00919.x
Manini, T. M., & Clark, B. C. (2012). Dynapenia and aging: An update. Journals ofGerontology. Series A, Biological Sciences and Medical Sciences, 67(1), 28–40. http://dx.doi.org/10.1093/gerona/glr010
Milne, S., Orbell, S., & Sheeran, P. (2002). Combining motivational and volitionalinterventions to promote exercise participation: Protection motivation theoryand implementation intentions. British Journal of Health Psychology, 7(Pt 2),163–184. http://dx.doi.org/10.1348/135910702169420
Newton, R. U., Gerber, A., Nimphius, S., Shim, J. K., Doan, B. K., Robertson, M., et al.(2006). Determination of functional strength imbalance of the lower extremities.Journal of Strength & Conditioning Research, 20(4), 971–977. http://dx.doi.org/10.1519/R-5050501x.1
Nyman, S. R., & Victor, C. R. (2012). Older people’s participation in and engagementwith falls prevention interventions in community settings: An augment to theCochrane systematic review. Age and Ageing, 41(1), 16–23. http://dx.doi.org/10.1093/ageing/afr103
Ostir, G. V., Volpato, S., Fried, L. P., Chaves, P., & Guralnik, J. M. (2002). Reliability andsensitivity to change assessed for a summary measure of lower body function:Results from the Women’s Health and Aging Study. Journal of Clinical Epidemiology,55(9), 916–921. S0895435602004365.
Rehn, B., Lidstrom, J., Skoglund, J., & Lindstrom, B. (2007). Effects on leg muscularperformance from whole-body vibration exercise: A systematic review. Scandina-vian Journal of Medicine and Science in Sports, 17(1), 2–11. doi: SMS578[pii]10.1111/j.1600-0838.2006.00578.x.
Rogan, S., & de Bruin, E. (2013). Skilling-up exercise for deconditioned nursing homedwellers. Paper presented at the 18th annual ECSS Congress.
Rogan, S., Radlinger, L., Schmdtbleicher, D., de Bie, R., & de Bruin, E. D. (2011).Application of whole-body vibration with stochastic resonance (SR-WBV) in frailelderly: The effect on postural control – A pilot study. BUAS.
Rogan, S., Hilfiker, R., Schmid, S., & Radlinger, L. (2012). Stochastic resonance whole-body vibration training for chair rising performance on untrained elderly: A pilotstudy. Archives of Gerontology and Geriatrics, 55(2), 468–473. http://dx.doi.org/10.1016/j.archger.2012.02.011
Rogan, S., Radlinger, L., Schmid, S., Herren, K., Hilfiker, R., & de Bruin, E. (2012). Skillingup for training: A feasibility study investigating acute effects of stochastic reso-nance whole-body vibration on postural control of older adults. Ageing Research,3(1), e5.
Rogan, S., Radlinger, L., Portner-Burkhalter, C., Sommer, A., & Schmdtbleicher, D. (2013).Feasibility study evaluating four weeks stochastic resonance whole-body vibrationtraining with healthy female students. International Journal of Kinesiology & SportsScience, 1, 1–10.
Rogan, S., Schmidtbleicher, D., & Radlinger, L. (2014). Immediate effects after stochasticresonance whole-body vibration on physical performance on frail elderly forskilling up training: A blind cross-over randomised pilot study. Aging Clin ExpRes [Epub ahead of print].
Rogers, M. A., & Evans, W. J. (1993). Changes in skeletal muscle with aging: Effects ofexercise training. Exercise and Sport Sciences Reviews, 21, 65–102.
Rosenberg, I. H. (1997). Sarcopenia: Origins and clinical relevance. Journal of Nutrition,127(5 (Suppl.)), 990S–991S.
Sitja-Rabert, M., Rigau, D., Fort Vanmeerghaeghe, A., Romero-Rodriguez, D., BonastreSubirana, M., & Bonfill, X. (2012). Efficacy of whole body vibration exercise in olderpeople: A systematic review. Disability and Rehabilitation, 34(11), 883–893. http://dx.doi.org/10.3109/09638288.2011.626486
Skelton, D. A., & Dinan, S. M. (1999). Exercise for falls management: Rationale for anexercise programme aimed at reducing postural instability. Physiotherapy Theoryand Practice, 15(2), 105–120.
Thabane, L., Ma, J., Chu, R., Cheng, J., Ismaila, A., Rios, L. P., et al. (2010). A tutorial onpilot studies: The what, why and how. BMC Medical Research Methodology, 10, 1.http://dx.doi.org/10.1186/1471-2288-10-1
Wall, J. C., Bell, C., Campbell, S., & Davis, J. (2000). The Timed Get-up-and-Go testrevisited: Measurement of the component tasks. Journal of Rehabilitation Researchand Development, 37(1), 109–113.
Wirth, K., Atzor, K. R., & Schmidtbleicher, D. (2007). Changes in muscle mass dependingon training frequency and level of experience. Deutsche Zeitschrift fur Sportmedizin,58(6), 178–183.
Zhang, L., Weng, C., Liu, M., Wang, Q., Liu, L., & He, Y. (2014). Effect of whole-bodyvibration exercise on mobility, balance ability and general health status in frailelderly patients: A pilot randomized controlled trial. Clinical Rehabilitation, 28(1),59–68. http://dx.doi.org/10.1177/0269215513492162
