The Effect of Power Training The Effect of Power Training versus Strength Training on Lower versus Strength Training on Lower Extremity Function in CommunityExtremity Function in Community--

Dwelling Older AdultsDwelling Older Adults

Jason CraigJason CraigCori HananCori HananRyan JeansRyan Jeans

Christina LangerChristina LangerJill MorrisJill Morris

Supervised by: Dr. Teresa LiuSupervised by: Dr. Teresa Liu--AmbroseAmbrose

OUTLINEOUTLINE

1.1. BackgroundBackground2.2. RationaleRationale3.3. MethodsMethods4.4. ResultsResults5.5. DiscussionDiscussion6.6. ConclusionConclusion7.7. RecommendationsRecommendations

BACKGROUNDBACKGROUND

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BackgroundBackground

Aging populationAging population2003, 13% of Canadians > 65 yrs2003, 13% of Canadians > 65 yrsBy 2031, 23% > 65 yrsBy 2031, 23% > 65 yrs

Increased proportion of older adults Increased proportion of older adults increase in chronic disease and coincrease in chronic disease and co--morbiditiesmorbidities

In 2006 4.3 million Canadians were 65 years or older, accounting for one third of Canada’s population (2). The number of senior citizens in Canada is increasing, which will place an increased demand on our health care system.

Background

SarcopeniaSarcopenia: the age related decline in : the age related decline in muscle mass resulting from a decrease in muscle mass resulting from a decrease in the size and number of muscle fibersthe size and number of muscle fibers22

decreased ability to produce force decreased ability to produce force increased risk of falls, impaired mobility, increased risk of falls, impaired mobility, decreased functional independencedecreased functional independence33

Background

Functional Independence: the ability to perform ADLs and IADLs without help from other individuals4

LE function is a major component of functional independence

Define LE Function

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BackgroundBackground

Resistance training combats sarcopenia and Resistance training combats sarcopenia and minimizes the decline in LE function in older minimizes the decline in LE function in older adultsadults88

reduces fall riskreduces fall riskdecreases falldecreases fall--related health care costs related health care costs reduces the loss of independencereduces the loss of independence

Falls are expensive, as they result in increased hospitalization and decreased functional independence in the older adult (10 and 11).

Strength and Power Training Strength and Power Training DefinitionsDefinitions

Strength training (ST)Strength training (ST)

multiplemultiple-- and singleand single--joint exercises joint exercises performed at a slow performed at a slow velocity for 1velocity for 1--3 sets 3 sets of 8of 8--10 reps at 6010 reps at 60--80% of 1RM80% of 1RM1515

Power training (PT)Power training (PT)

multiplemultiple-- and singleand single--joint exercises joint exercises performed at a high performed at a high velocity for 1velocity for 1--3 sets 3 sets of 6of 6--10 reps at 4010 reps at 40--60% 1RM60% 1RM1515

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Strength TrainingStrength Training

Positive effects of ST on the older adult:Positive effects of ST on the older adult:improved muscle performance improved muscle performance Improved bone health Improved bone health attenuation of sarcopeniaattenuation of sarcopenia99

ST has become a routinely prescribed ST has become a routinely prescribed form of exercise for older adultsform of exercise for older adults99

The first randomized controlled trials (RCTs) studying the effects of ST on muscle mass in the elderly appeared in the literature twenty-five years ago (9).

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Power TrainingPower TrainingPT is emerging as an alternative form of PT is emerging as an alternative form of resistance training for older adults resistance training for older adults

Impaired physical performance may be due to a Impaired physical performance may be due to a lack of muscle power rather than a lack of lack of muscle power rather than a lack of strength.strength.14 14 Motor tasks performed under daily Motor tasks performed under daily conditions require movements at higher speeds conditions require movements at higher speeds and variable external resistanceand variable external resistance99

The effects of PT on sarcopenia have not been The effects of PT on sarcopenia have not been thoroughly studiedthoroughly studied1313

and may be a more effective intervention than strength training for improving function and decreasing disability in the elderly (12).

RationaleRationale

Two systematic reviews have examined the Two systematic reviews have examined the effect of ST on LE function in the older adulteffect of ST on LE function in the older adult8, 148, 14

reviews reported positive effect of ST on lower reviews reported positive effect of ST on lower extremity (LE) strength; few RCTs utilized outcome extremity (LE) strength; few RCTs utilized outcome measures relevant to LE function in older adults such measures relevant to LE function in older adults such as sit to stand abilityas sit to stand ability8, 148, 14

RationaleRationale

No published systematic reviews No published systematic reviews comparing the effects of PT versus STcomparing the effects of PT versus ST

Unclear which form of resistance training is Unclear which form of resistance training is more effective in improving LE function in more effective in improving LE function in older men and womenolder men and women

Systematic Review PurposeSystematic Review Purpose

1.1. Examine the effect of PT versus ST on LE Examine the effect of PT versus ST on LE function in communityfunction in community--dwelling older dwelling older adultsadults

2.2. Determine the optimal method of Determine the optimal method of resistance training to maintain and resistance training to maintain and improve LE function in the older adultimprove LE function in the older adult

Define LE function

METHODSMETHODS1.1. Inclusion CriteriaInclusion Criteria2.2. Search StrategySearch Strategy3.3. Study SelectionStudy Selection4.4. Data ExtractionData Extraction5.5. Study QualityStudy Quality6.6. Data AnalysisData Analysis

Inclusion CriteriaInclusion Criteria

1)1) Mean age of 65 years or olderMean age of 65 years or older

2)2) Independent, communityIndependent, community--dwelling adultsdwelling adults

3)3) Direct comparison of ST and PTDirect comparison of ST and PT

4)4) Published in English Published in English

5)5) Supervised exercise interventionSupervised exercise intervention

6)6) Minimum of one LE function outcome measureMinimum of one LE function outcome measure

1) Mean age of 65 years or older

2) Independent, community-dwelling adults-For example, papers had to mention that subjects were independent with daily

living or were well functioning.

3) Direct comparison of only ST and PT-No combined training (i.e. no aerobic ex)

4) Published in English

5) Supervised exercise intervention

6) Minimum of one LE function outcome measure

Outcome Measure: LE functionOutcome Measure: LE functionA tool that assesses components of ADLs involving the LE

Examples of acceptable LE function outcome Examples of acceptable LE function outcome measures include:measures include:

1) gait speed 1) gait speed 2) chair2) chair--rise time rise time 3) functional reach 3) functional reach 4) static and dynamic balance4) static and dynamic balance

Search StrategySearch StrategyJournal articles were selected from numerous Journal articles were selected from numerous databases including: databases including:

1.1. MEDLINEMEDLINE2.2. CINAHLCINAHL3.3. EBM ReviewsEBM Reviews4.4. Sports DiscusSports Discus5.5. EMBASEEMBASE

Other Sources:Other Sources:1.1. ProQuest and National Research Register for ProQuest and National Research Register for

unpublished theses unpublished theses 2.2. Google scholarGoogle scholar3.3. Experts in the field Experts in the field 4.4. Hand searchingHand searching

Search TermsSearch TermsPower trainingPower training •• high velocity resistance training high velocity resistance training

•• high intensity resistance training high intensity resistance training •• plyometrics plyometrics •• speed trainingspeed training

Strength Strength trainingtraining

•• resistance training resistance training •• weight lifting weight lifting •• resistance exercise resistance exercise •• low velocity resistance training low velocity resistance training •• low intensity resistance traininglow intensity resistance training

Search StrategySearch Strategy

The search was further limited to:The search was further limited to:

1.1. Humans Humans 2.2. English language English language 3.3. Age 65 years or older, or was combined Age 65 years or older, or was combined

with keywords for older adults (aged, with keywords for older adults (aged, elder, geriatric, senior, older people)elder, geriatric, senior, older people)

Data ExtractionData Extraction

Developed and pilot tested own data extraction Developed and pilot tested own data extraction tool from multiple sourcestool from multiple sources

Data extraction included: Data extraction included:

1.1. Study characteristicsStudy characteristics2.2. Intervention characteristicsIntervention characteristics3.3. Outcome measuresOutcome measures4.4. DropDrop--Outs and Adverse EventsOuts and Adverse Events5.5. Study qualityStudy quality6.6. Major study conclusionsMajor study conclusions

Study Quality and Level of Study Quality and Level of EvidenceEvidence

PEDroPEDro88--10 = Excellent10 = Excellent66--7 = Good7 = Good44--5 = Moderate5 = Moderate11--3 = Poor3 = Poor

Oxford CEBM Levels Oxford CEBM Levels of Evidenceof Evidence

•To assess the quality of the included studies two independent reviewers used the PEDro scale and the Oxford Center of Evidence Based Medicine Levels of Evidence.

•PEDro, is a 11 item quality AX tool, designed primarily for the evaluation of physiotherapy-based studies

•Although there are limitations to using the PEDro scale such as the difficulty in PT interventions to blind subjects to their tx group, it was sensitive to differences in the quality of the included studies.

• A third reviewer resolved any disagreements regarding PEDro scores or the level of evidence assigned to a study.

Data AnalysisData AnalysisA metaA meta--analysis was planned initially, but was not analysis was planned initially, but was not performed because of statistical and clinical performed because of statistical and clinical heterogeneityheterogeneity

Standardized mean differences and 95% confidence Standardized mean differences and 95% confidence intervals (CI) were calculated for continuous outcome intervals (CI) were calculated for continuous outcome measures using Hedges adjusted measures using Hedges adjusted gg, which accounts for , which accounts for small sample size. small sample size.

Conventional effect sizes used.Conventional effect sizes used.•• 0.2 = small0.2 = small•• 00.5 = medium.5 = medium•• 0.8 = large0.8 = large

Cohen’s d does not account for sample size.

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Data AnalysisNo significant differences at baseline, therefore No significant differences at baseline, therefore postpost--test scores were used for effect size test scores were used for effect size calculation.calculation.

Only outcome measures that were utilised in Only outcome measures that were utilised in the majority of studies were analysed.the majority of studies were analysed.

Primary analysis compared PT vs STPrimary analysis compared PT vs ST

Secondary analysis compared PT and ST vs Secondary analysis compared PT and ST vs controlcontrol

RESULTSRESULTS

Study SelectionStudy Selection

Excluded by screening abstracts (N = 165 )

Excluded by removing duplicates (N= 77)

•Two reviewers independently screened titles and then abstracts from the database searches to identify potentially relevant articles.

•Disagreements during the first two stages of screening were resolved by including the studies for the next stage of review to eliminate selection bias.

•After removal of duplicates 94 articles remained.

Excluded after evaluation of abstracts (N = 65)•Not head to head•Not supervised•Age

Excluded from SR (N = 23)•No functional outcome•No PT component

•Full evaluation of abstracts excluded several more articles (for reasons such as not a head to head comparison, not a supervised ex. intervention, and age limitations). 29 articles remained.

•Full text copies of the selected studies were then obtained and two reviewers independently reviewed the articles to determine if inclusion criteria were met. Articles were excluded for several reasons (no functional outcome measures, no PT). Any disagreements during the final stage of study selection were resolved by a third reviewer.

•In the end 6 RCTs remained for data extraction.

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Study Quality and Level of Study Quality and Level of EvidenceEvidence

PEDroPEDroGood quality = 3 Good quality = 3 Moderate quality = 2Moderate quality = 2Poor quality = 1 Poor quality = 1

Intention to treat = 0Intention to treat = 0Blinding = 2 Blinding = 2

Oxford CEBM Levels of EvidenceOxford CEBM Levels of EvidenceAll 2B, low quality RCTsAll 2B, low quality RCTs

Explain what pedro scores mean

Study CharacteristicsStudy CharacteristicsControl group = 3Control group = 3No control group = 3 No control group = 3

All studies performed in a structured setting All studies performed in a structured setting

Female only = 3Female only = 3Male only = 1Male only = 1Male and female = 2 Male and female = 2

Sample size = 20Sample size = 20--61 subjects61 subjectsAge range = 60Age range = 60--90 years90 years

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Study CharacteristicsStudy CharacteristicsDropDrop--outs outs

11--11 subjects, with an average of 5 per study11 subjects, with an average of 5 per study

Adverse events Adverse events Reported = 3/Unreported = 3Reported = 3/Unreported = 3

Compliance:Compliance:Reported = 3/Unreported = 3Reported = 3/Unreported = 38888--95 % compliance was recorded95 % compliance was recorded

No treatment group had disproportionate dropNo treatment group had disproportionate drop--outs, outs, adverse events or compliance.adverse events or compliance.

Reasons for drop-out included transportation, personal and family complications, medical issues, and time commitments.

Reported adverse events included exacerbation of plantar fasciitis and pre-existing osteoarthritis (Sayers), as well as six falls and three musculoskeletal injuries including a hamstring tear (Mizko).

Intervention CharacteristicsIntervention CharacteristicsNUMBER OF EXERCISES

•6-8 exercises = 4 studies•2-4 exercises = 2 studies

SETS 1-3

REPETITIONS 6-8

TRAINING DURATION

8-16 weeks

FREQUENCY 2-3 times per week

INTENSITY •Strength: Ranged from body weight to 80% 1RM

•Power: Ranged from 40-75% 1RM with exception of the weighted vest

Number of Exercise……

The types of exercise performed in the studies were:

1) leg press (4 studies), 2) knee ext.(all studies), 3) leg curl (5 studies), 4) ankle PF (3 studies), 5) squats (1 study), 6) hip flexion (1 study), 7) chair stands (1 study)

4 studies also included upper extremity exercises in their program such as chest press, seated row, bicep curl, and tricep ext.

All these characteristics met ACSM guidelines for PT and ST except:1. one study that used BW for ST and a weighted vest for PT as their intensity

levels.

The weighted vest was increased by 2% of the subjects BW if the subject was able to perform prior weight with no difficulty.

Intervention CharacteristicsIntervention CharacteristicsExercise Speed (Tempo)

•PT groups completed the exercise as fast as possible •ST exercises were performed over 4-6 seconds

Equipment •Weight machines = 5•Body weight for ST and weighted vest for PT = 1

Familiarization period

2 studies:•1 included within the treatment time•1 done prior to baseline measures

•PT groups completed the exercise as fast as possible •ST exercises were performed over 4-6 seconds

5 studies used various types of exercise equipment, such as an isokinetic dynamometer, Keiser pneumatic equip., Extek resistance equip., and 1 study performed all ex. Sitting in a chair using BW or BW + Weighted Vest.

A familiarization period was included by 2 studies with one being performed before baseline and the other within treatment time.

All these characteristics met ACSM guidelines for PT and ST.

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Data Analysis ResultsData Analysis Results

Effect sizes and 95% Effect sizes and 95% CI were calculated CI were calculated for: for:

PT vs ST PT vs ST PT vs Control PT vs Control ST vs ControlST vs Control

For the following For the following outcome measures:outcome measures:

LE strength LE strength LE powerLE powerChair rise functionChair rise functionGait velocityGait velocity

As a meta- analysis was not performed due to clinical and statistical heterogeniety between the studies, hedges adjusted g effect sizes and 95% CI were calculated. Our primary comparison was PT vs. ST, however, we also performed secondary comparisons of PT vs. Control and ST vs. Control. The outcome measures of LE strength, LE power, Chair rise function, and gait velocity were selected for analysis because they were utilized in the majority of the included studies. Note, complete data was not obtained for two studies (Sayers, Bean) despite

efforts to contact authors for additional data. As a result, change mean scores and standard deviations were used for data analysis where available (Bean).

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LE Strength LE Strength (PT vs ST)(PT vs ST)Figure 2. PT versus ST for LE Strength (1RM Leg Press, Kg)Figure 2. PT versus ST for LE Strength (1RM Leg Press, Kg)

** Isokinetic knee extension peak torque @ 60 degrees/sec (Nm)Isokinetic knee extension peak torque @ 60 degrees/sec (Nm)

*

Our first primary comparison was …….The outcome measure was the same for all studies except Carmel, which used isokinetic knee ext. as their outcome.To reiterate the effect size levels, a small effect = 0.2, a medium effect = 0.5, and a large effect = 0.8.For this outcome, effect sizes ranged from negligible at 0.05 to medium at 0.68. However, no clear effect was evident for PT vs. ST as shown by the inconsistent effect measures and large and variable confidence intervals. It is also important to note that No statistical significant differences were found between groups for any of the studies.Therefore, we could not conclude which training intervention was more effective at improving LE strength

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LE Power (PT vs ST)LE Power (PT vs ST)Figure 3. PT versus ST for LE Power (Leg Press Peak Power, W)Figure 3. PT versus ST for LE Power (Leg Press Peak Power, W)

* * Isokinetic knee extension average power @ 300 deg/sec (W)Isokinetic knee extension average power @ 300 deg/sec (W)

**** Wingate anaerobic cycle test (W)Wingate anaerobic cycle test (W)ββ Significant difference for PT v. ST groupsSignificant difference for PT v. ST groups

***β

β

Our next comparison was………..The outcome measure used by 2 studies was leg press peak power, whereas, the study by Bean used the Wingate anaerobic cycle test for peak power, and the Carmel study used isokinetic knee ext. average power. All measures analysed power in watts.For this outcome, effect sizes ranged from small at 0.16 to large at 2.87.Two studies were inconclusive about treatment efficacy (miz, car), as evident by small effect sizes and variable CI’s.On the otherhand, two studies clearly favored PT, as evident by large effect sizes and consistent CI’s supporting PT. Also, both studies found a statistical significant difference for PT vs. ST on this outcome.Therefore, we could conclude from this analysis that PT may be more effective at improving LE Power compared to ST.

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Chair Rise (PT vs. ST)Chair Rise (PT vs. ST)Figure 4. PT versus ST for Chair Rise Function (Stand up & sit Figure 4. PT versus ST for Chair Rise Function (Stand up & sit

down, seconds)down, seconds)

** number of chair stands in 30 secondsnumber of chair stands in 30 secondsββ Significant difference for PT versus ST groupsSignificant difference for PT versus ST groups

β

*β

Our next comparison was……….The outcome measure used by 3 studies was stand up & sit down measured in seconds. Whereas the study by Bottaro used the number of chair stands in 30 secs to measure this outcome.For this outcome, effect sizes ranged from small at 0.43 to large at 1.72.All studies favored the PT group with 2 studies displaying a large effect that clearly favors PT, and 2 studies having small to medium effects. However, the study by Bottaro was not as conclusive due to the variable CI. 2 studies, Bean that clearly favors PT, and Bottaro that is inconclusive, found a statistical significant difference for PT versus ST.Therefore, we could conclude from this analysis that PT may be more effective at improving chair rise function compared to ST. However caution must be taken when drawing conclusions due to the lack of statistical significance across all studies, particularly those that appear to favour PT.

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Gait Velocity Gait Velocity (PT vs. ST)(PT vs. ST)Figure 5. PT v. ST for Gait Velocity (Gait velocity, m/s)Figure 5. PT v. ST for Gait Velocity (Gait velocity, m/s)

*

**

***

** Time to walk 2.4m (Gait velocity calculated from time and distaTime to walk 2.4m (Gait velocity calculated from time and distance)nce)

**** Time to walk 15ft (Gait velocity calculated from time and distaTime to walk 15ft (Gait velocity calculated from time and distance)nce)

****** Time to walk 6m (seconds)Time to walk 6m (seconds)

Lastly, we compared……….The outcome measures used by 2 studies was Gait velocity in m/sec, whereas the study by Henwood measured time to walk 6m in seconds. Distances walked ranged from 2.4m to 6m.For this outcome, effect sizes ranged from no effect at 0.0 to medium at 0.45. The study by Carmel had an insignificant effect size with a large and variable CI, thus making the result inconclusive.And the study by Bean had a medium effect size favoring PT, however the large

and variable CI makes the result inconclusive again.Also, No statistical significant differences for PT vs ST were found for any of the studies.Therefore, we could not conclude which training intervention was more effective at improving Gait Velocity.

Continuous Scale Physical Function Performance (CSContinuous Scale Physical Function Performance (CS--PFP) test, a global outcome PFP) test, a global outcome measure for function, was used for one study. measure for function, was used for one study. A large effect size, favoring the power training group (SMD 0.79A large effect size, favoring the power training group (SMD 0.79;95% CI ;95% CI --0.04,1.63) 0.04,1.63) was calculated for the CSwas calculated for the CS--PFP total score. Statistical significance found for PT vs. PFP total score. Statistical significance found for PT vs. STST

ST vs Control for analyzed ST vs Control for analyzed outcome measuresoutcome measures

Data was obtained from the three studies that had control groupsData was obtained from the three studies that had control groups. . Large and medium effect sizes for LE strength favored strength Large and medium effect sizes for LE strength favored strength training for all three studies. Significant difference found in training for all three studies. Significant difference found in 2 studies.2 studies.

Medium effect sizes favoring strength training were also calculMedium effect sizes favoring strength training were also calculated ated on LE power for two studies. No significant difference found in on LE power for two studies. No significant difference found in either either study.study.

Chair rise performance favored the control group for one study aChair rise performance favored the control group for one study and nd strength training for the other. No significant difference foundstrength training for the other. No significant difference found for for either study.either study.

A small gait velocity effect size favored the control group for A small gait velocity effect size favored the control group for one one study and a medium effect size favored strength training for thestudy and a medium effect size favored strength training for theother. Significant difference found in one study in favor of conother. Significant difference found in one study in favor of control trol group.group.

Conclusions:

LE Strength – ST may be > Cont LE Power – ST may be > Cont, however caution as no sig. diff. and only med effect.Chair Rise – inconclusiveGait Velocity - inconclusive

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PT vs. Control for analyzed PT vs. Control for analyzed outcome measuresoutcome measures

Of the three studies that had control groups, insignificant Of the three studies that had control groups, insignificant to large effect sizes favoring the PT group were found for to large effect sizes favoring the PT group were found for LE strength. Significant difference found in one study LE strength. Significant difference found in one study only. only.

Medium and large effect sizes for LE power and chair Medium and large effect sizes for LE power and chair rise function favored the PT group respectively. rise function favored the PT group respectively. Significant difference found for one study for chair rise Significant difference found for one study for chair rise function.function.

The control group was favored for one study and PT The control group was favored for one study and PT group for one study, for measures of gait velocity. No group for one study, for measures of gait velocity. No significant differences found for either study.significant differences found for either study.

Conclusions:

LE Strength – PT may be > Cont.LE Power – PT may be > Cont., however caution due to no significant diff and variable CIChair Rise – PT may be > Cont.Gait Velocity – Inconclusive

Comprehensive Conclusion:

LE Strength – PT = ST, PT & ST may be > Cont.LE Power – PT may be > ST, PT & ST may be > Cont with CautionChair Rise – PT may be > ST with Caution, PT may be > Cont., ST = ContGait Velocity – PT = ST, PT = Cont., ST = Cont.

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DISCUSSIONDISCUSSION

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Methodological Quality of PapersMethodological Quality of Papers

A major finding was that research A major finding was that research conducted on the topic was generally conducted on the topic was generally lacking methodological qualitylacking methodological quality

Lack of blinding and intention to treatLack of blinding and intention to treat

Due to the nature of the physiotherapy interventions in the included studies, it was only possible to blind the assessors; however, only two of the six studies did so (Be, Ca).

Without blinding and intention to treat, there is an increased risk for observation bias which may influence recording and reporting of outcomes; therefore, caution is required when drawing conclusions from this data.

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Sample SizeSample Size

All studies had small sample sizes, ranging from All studies had small sample sizes, ranging from 20 to 61 participants 20 to 61 participants

No preNo pre--hoc power analysishoc power analysis

A postA post--hoc power analysis concluded that a hoc power analysis concluded that a sample size between 46 and 150 subjects per sample size between 46 and 150 subjects per group would be necessary to identify differences group would be necessary to identify differences in functional outcome measuresin functional outcome measures

In a post-hoc power analysis, Sayers et al concluded that a sample size between 46 and 150 subjects per group would be necessary to identify differences in functional outcome measures between power and strength training groups.

Sample & Outcome Measure Sample & Outcome Measure CharacteristicsCharacteristics

The inclusion of communityThe inclusion of community--dwelling older dwelling older adults may account for the limited amount adults may account for the limited amount of change observed in the studies of change observed in the studies

A ceiling effect may have limited the gains A ceiling effect may have limited the gains in functional performancein functional performance

Adverse EventsAdverse Events

Although there were no reports of serious injury Although there were no reports of serious injury associated with PT or ST, adverse events were associated with PT or ST, adverse events were poorly reported/defined in most of the trials poorly reported/defined in most of the trials

This makes it difficult to come to a definite This makes it difficult to come to a definite decision regarding the safety of PT and ST decision regarding the safety of PT and ST

It is important to note that inactivity also has It is important to note that inactivity also has serious negative consequences for older peopleserious negative consequences for older people

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Intervention Design: Intervention Design: FamiliarizationFamiliarization

Two studies utilized a familiarization Two studies utilized a familiarization periodperiod

Initial gains in strength during resistance Initial gains in strength during resistance training have been attributed to neural training have been attributed to neural adaptations resulting in increased muscle adaptations resulting in increased muscle fiber recruitment, rather than actual fiber recruitment, rather than actual increase in muscle sizeincrease in muscle size99

The lack of familiarization period in other studies may confound the results, with the score changes potentially being a product of motor learning versus a power or strength training effect. In addition, a familiarization period may potentially increase safety and thereby decrease number of adverse events. (REF ??)

Intervention Design:Intervention Design:Training SpecificityTraining Specificity

Most studies employed nonMost studies employed non--functional exercisesfunctional exercises

1 study included functional exercises of sit1 study included functional exercises of sit--toto--stand and step up. There was significant stand and step up. There was significant improvement in chairimprovement in chair--rise time rise time

Improvement in functional performance may be enhanced by using function-specific exercises

Intervention Design:Intervention Design:CharacteristicsCharacteristics

It requires 3It requires 3--4 months, 24 months, 2--3 times a week of 3 times a week of training to have a 2 to 3 times increase in training to have a 2 to 3 times increase in strength from baselinestrength from baseline99

4 of 6 studies met this criteria4 of 6 studies met this criteria

Intervention Design:Intervention Design:CharacteristicsCharacteristics

Various workloads were used between studies Various workloads were used between studies with no definitive conclusion on an ideal with no definitive conclusion on an ideal absolute total workabsolute total work

With a lower workload there may be With a lower workload there may be increased exercise compliance and relatively increased exercise compliance and relatively lower perceived exertionlower perceived exertion1313

CONCLUSIONCONCLUSION

ConclusionConclusionThe results are inconclusive as to the effectiveness The results are inconclusive as to the effectiveness of PT versus ST on LE function in communityof PT versus ST on LE function in community--dwelling older adults dwelling older adults

Three of the six studies found that PT was Three of the six studies found that PT was significantly more effective than ST for improving significantly more effective than ST for improving LE function in older adults LE function in older adults

Three of the six studies found no significant Three of the six studies found no significant difference between PT and ST.difference between PT and ST.

ConclusionConclusion

Although the results were inconclusive in this Although the results were inconclusive in this review, a trend was evident that power training review, a trend was evident that power training may be as effective or better in improving may be as effective or better in improving functional measures in older adults when functional measures in older adults when compared to strength trainingcompared to strength training

The inability of this review to find a conclusive The inability of this review to find a conclusive answer is partially due to the moderate to low answer is partially due to the moderate to low quality of the included studiesquality of the included studies

RECOMMENDATIONSRECOMMENDATIONS

RecommendationsRecommendations1.1. Utilize rigorous research designs that minimize Utilize rigorous research designs that minimize

bias, have an adequate sample size and bias, have an adequate sample size and carefully monitor adverse events carefully monitor adverse events

2.2. Expanded sample population to atExpanded sample population to at--risk risk participants, such as older adults with preparticipants, such as older adults with pre--existing functional limitations and disability existing functional limitations and disability

3.3. Perform followPerform follow--up assessment to determine up assessment to determine the longthe long--term effects of the interventionsterm effects of the interventions

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