Relationship and hospitalizations. Purpose: To investigate the relationship

Relationship Between Balance and Muscle Strength of The Lower
Extremities in Healthy Middle-Aged Women

Collage of Applied Medical Sciences



Background: Most middle- aged women, even the healthy ones, have
some impairments, such as muscle weakness and loss of balance. This increases
the likelihood of falling, which causes serious complications, deteriorates the
overall health status, impaires their day-to-day functioning, and increases
their physical dependency and hospitalizations. Purpose: To investigate the
relationship between muscle strength of the lower extremities and balance in
healthy middle-aged women. Methods: Muscle strength will be measured using
hand-held dynamometer. While balance will be measured by one-leg standing test
and timed Get-Up and Go test (GUG). Data analysis: Statistical analysis will be
carried out using SPSS software. Pearson correlation coefficient test will be
used to investigate the relationship between muscle strength and balance and
interaction between participants’ characteristics (Age, BMI). The spearman
correlation coefficient test will be used to investigate the relationship
between other participants’ characteristics, muscle strength and balance. The
values will be considered statistically significant at P ? 0.05.

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Aging is a normal process that all
people pass through within their lifespan, but it may differs between individuals
due to genetic and environmental factors (P1 et al., 2014). When a person gets older, there is an overall gradual decrease of
physical capacity, muscle power, sensation, and coordination, which leads to
balance deficits) Oliveira et al., 2014). An adequate level of balance is required in middle-aged
people to successfully perform everyday normal activities) Muehlbauer et al., 2012). Researchers define balance as the preservation of ideal body
posture during dynamic and static states by producing suitable motor responses
to facilitate voluntary movements and recover equilibrium) Lord, 2008; Mancini & Horak, 2010). For instance, isometric and dynamic muscle strength reaches its
peak around age 20-29 years old and deteriorates in persons 50-59 years old due
to a reduction in individual muscle fiber counts, particularly among fast
twitch fibers type II, that reduces overall skeletal muscle size (P1 et al., 2014).  As a result, elderly  people are more prone to depend on others to
maintain their balance and protect themselves from falling )Liu CJ 1,  2017; Muehlbauer, 2015).

In this context, the other factor
that needs to be considered is muscle strength. “Muscle strength should be
distinguished from muscle power: muscle strength is defined as the maximal
force that a muscle can produce against a given resistance, while muscle power
(force × velocity) is defined as the product of force and speed.” Thus, to
prevent falling, interventions should focus on muscle power enhancement instead
of muscle strength (Winzenberg, 2016(. For more stability, the muscle power of middle-aged people
should be equal between the right and left lower extremities. Differential
muscle power between the left and right sides leads to instability) Kim MK 1, 2015(.

Balance and muscle power are
critical for good health and physical strength and should be improved or
maintained adequately throughout one’s lifespan to be able to play sports and
conduct everyday activities without accidents like falling
(Muehlbauer, 2015(. Physical fitness is an effective strategy to enhance
equilibrium and decrease sarcopenia (Oliveira et al., 2014). The lower limb muscle strength evaluation is commonly used to
study balance in middle age. Accordingly, this study will regard muscle
strength as a measurement tool for balance (Wang H1,  2016) .

Middle-aged people with reduced
physical capacity are more likely to depend on others to conduct everyday
activies. Liu CJ et al. (2017) studied the effects of physical activity  with decrease 
physical capacity in elderly with age 75 years or older people and their
risk of need to care giver in their daily activity . Using a meta-analysis study,
their findings showed that multimodal exercises are effective in reducing
falls, increase muscle strength, balance and physical function of the lower

Two recent studies have reported
that physical exercise directly affects muscle power and the capacity to
preserve balance. Hyo-Cheol Lee et al. (2015) examined the influence of
physical exercise by elderly women on muscle function and balance in 20 healthy
elderly women aged 60 and over by separating them into control group and
exercise group. The exercise group subjects participated in an elastic band
exercise program lasting for 8 weeks, exercising for 40 minutes four days a
week with resting periods of 60 seconds. They measured sit-to-stand capacity to
evaluate muscle strength, knees-up exercises for two minutes to measure muscle
endurance and standing on one leg with eyes open to test balance. They found
that strength and endurance of the quadriceps femoris muscle markedly increased
in the exercise group following the intervention. The ability to balance
markedly improved in the exercise group, exhibiting that the intervention is
efficacious at developing balance, muscle strength and endurance of middle age
women. The other study was conducted by Eckardt (2016) as a randomized control
trial on 75 healthy community-dwelling aged 65-80 years to detect if resistance
exercise of lower extremity on unstable surfaces will affect muscle strength
and balance. The author assigned them to three intervention groups: machine-based
unstable resistance training M-URT, machine-based stable resistance training
M-SRT, and free-weight unstable resistance training F-URT. For ten weeks,
all groups exercised two times per week with each exercising session lasting
~60 min. Tests contained assessment of power (e.g., chair rise test), leg
muscle strength (e.g., maximal isometric leg extension strength) and balance
(e.g., functional reach test), carried out pre-and post the training period.
The results revealed that lower-extremity resistance training conducted on both
surfaces markedly increased proxies of strength, power and balance in all
groups. The greatest improvements in leg extension strength produced by M-URT and
F-URT in the chair rise test and functional reach test.

Aging correlates with changes in body musculature. Thus, Castro et
al. (2014) studied the relationship between physical ability, muscle strength
and muscle mass in 100 physically independent healthy elderly women aged ? 65
years old. Dual-energy x-ray absorptiometry (DXA) were assess the body
composition and bone mass. Isokinetic dynamometry was assessed the knee
extension and flexion strength, and physical ability was measured by timed Get
Up and Go test (TUG), dynamic Gait index (DGI) and Berg Balance test (BBT). Age
and muscle strength showed a significant association even without a significant
effect of age on muscle mass.

Middle-aged individuals, even the
healthy ones, may suffer from instability and impaired balance. Weirich et al
(2010) studied the predictors of balance in young, middle-aged, and late
middle-aged women in eighty-five female ages between 18 and 64 years in knee
extensor, leg press and knee flexor. Evaluation with maximal muscular strength
for the lower extremities (knee extensor, leg press, and knee flexor), lower
extremity flexibility (plantar flexion, dorsiflexion, hip flexion, and sit and
reach) and total bone mineral density (BMD) and bone mineral content (BMC),
total and regional body composition (lean body mass and fat mass), balance and
postural stability. The results showed a significant relationship between
balance and age.

Most middle-age are face health
problems. One of the main problems is falling. Therefore, Ding Li et al. (2016)
investigated the relevance between muscle weakness and slip-initiated falls
among community-dwelling in Thirty-six healthy older male adults of age
71.3±4.7 years, in knee extensors and flexors muscles. Evaluation of muscle strength
and slip perturbation muscle strength (torque) was evaluated for the right knee
under maximum voluntary isometric (flexor and extensor) contractions. They were
then proceed to a specific treadmill. The authors reported a significant relevance
between muscle weakness and slip-initiated falls among community-dwelling
middle-aged men.

Other studies have also reported the
relation between balance and muscle strength. For instance, F. Wu and his
colleagues (2016) examined the association between lower limb muscle strength
and its association with poor balance in middle-aged women. The study examined
strength in quadriceps and hip extensor muscles cross-sectional analysis sample
involved of among 345 women of age 36–57. There was a significant association
between lower limb muscle strength and poor balance in middle aged women. In
another study, Chandak and his colleagues (2014) examined balance performance
and lower limb isometric muscle strength, particularly in the hip flexors,
extensors, abductors and adductors, knee flexors and extensors, ankle plantar-flexors
and dorsi-flexors in 100 community-dwelling middle-aged women of ages 60 and more
by using the Fullerton Advanced Balance (FAB) scale and handheld dynamometer.
They found that knee extensor strength correlated better with balance as
compared to other muscles, while the hip adductors weakly correlated with
balance. That is, women with higher knee extensor strength have better balance.
In addition, Abd El- Kader and Ashmawy (2014) investigated the relationship
between ankle dorsi-flexors strength and balance performance improvement in
fifty healthy middle aged male participants with age ranged between 65 and 75
years. Twenty-five participants were exercising group which trained with
resisted exercises and electrical nerve stimulation of ankle dorsi-flexors
muscles three times per week for 2 months. The control group, which contains twenty-five
participants, got encouragement for practicing their regular daily activities
over the 2 months of the study. The ankle dorsi-flexors muscles force was
measured by handheld dynamometer in kilograms, and the balance control was
measured by the Berg Balance Scale (BBS), and timed Get-Up and -Go test (GUG).
The Pearson’s correlation coefficients test for the relationship between BBS
scores and ankle dorsi-flexor muscles strength in both groups showed a strong
direct relationship. Conversely, there was an inverse direct relationship
between GUG and ankle dorsi-flexor muscles strength in both groups.

The Most researchers who have
researched the relationship between lower extremity muscle strength and balance
in healthy middle-aged individuals studied subjects ages 60 years old and
above, did not examine females, and/or they did not cover all lower extremity
muscle groups in their studies. The existing literature is deficient in these
respects and requires further investigations to determine the relationship
between lower extremity muscle strength and balance in healthy middle-aged
women, as it has been reported that the likelihood of  falling for middle-aged people increases from
the age of 50 and onwards years old (P1 et al. , 2014). Therefore, this study aims to cover, first, all lower extremity
muscle groups, and, second, to include healthy middle-aged women of age between
45 and 60 years old . The null hypothesis for the proposed study is: there is
no relationship between balance and lower extremity strength in middle-aged
healthy women. The alternative hypothesis is: there is a relationship between
balance and lower extremity strength in middle-aged healthy women.  Accordingly, the question of this study will
be: is there a relationship between balance and lower extremity strength in
middle-aged healthy women?

and methods:
Study design: Cross-sectional correlation study.

Participants: Forty healthy middle-aged
women of age from 45 to 60 years old will be covered in this study. They will
be recruited from the community. Participant information sheet will be
distributed in malls of the eastern region and women’s gathering places with
contact details of the researcher. If they are willing to take part in the
study, they will contact the research team. They will then be invited to the
university and measurement tests will be carried out. Participants will be
excluded if they have neurological disorders, any musculoskeletal problems, cognitive
deficits, any cardiopulmonary diseases, or if they consume medications that affect balance, as these factors may
affect balance outcomes. They will be included only if they are healthy, if
they are women, and if they are 45 – 60 years old.


The subjects will come to a clinical lab in
Imam Abdulrahman Bin Faisal University. They will be educated about the entire
process and should be sign a consent form. Furthermore, they will be required
to complete a personal information form.

The therapist will then perform the following
steps with the subjects:

1-      Measerment
of muscle strength of both lower limbs using the hand-held dynamometer. This
step will take 5 -10 minutes.

2-      Measurement
of balance by one-leg-stand test and Time up-and-go test. These will take 5 -10

3-      Rest
between the two steps and a snack will be provided.

4-      Transportation
will be provided to the subjects to and from the university lab.


To test muscle strength, the following
procedure will be employed:

The therapist will put the participant in a
proper comfortable position, then measure muscle strength in both lower limbs
with a hand-held dynamometer to see how vigorously the participants can
contract their (hip flexors, extensors, abductors, adductors, external
rotators, internal rotators, knee flexors and extensors, ankle dorsiflexors and
planter flexors). Then therapist will place the device in a proper position and
lean over the participant’s leg to provide the appropriate resistance and gain
an accurate reading, while asking the participant to try as hard as she can to
move the tested joint as the practitioner exerts force in the opposite
direction with the muscle testing device pressed against the patient’s
limb. Once the muscle testing device is in place, the therapist will
instruct the participant to press back against the device as hard as possible
for 4-5 seconds. The participant will take approximately one to two seconds to
exert maximum muscle force.

To test balance, the following procedure will
be employed:

1)One leg stands:

The therapist will instruct the participant to
stand for as long as she can on one leg, or until tell her to stop.
Chair/table/counter will be used for initial support. The participant can
select either foot to stand on, hold her foot anywhere, put not brace free leg
on the standing one. The participant arms should be at each sides while try not
to move unless she need to regain her balance. The therapist will start timing
when participant’s hand leaves the chair/table, and stop timing when
participant’s free foot contacts the ground, their hand touches the
chair/table, their foot moved, or time passed 30 seconds. Another therapist
must be close enough to guard the participant. The time must document to a
tenth of a second. Less than 10 seconds indicate balance problem and less than
5 seconds indicate fall risks.

 2) time
up-and-go test:

therapist will instruct the participant to sit right in arm rest chair. The
chair should be steady and placed so that it will not move when the participant
change position from sit to stand position. The therapist will put tape or
other type of  marker on the ground 3
meters away from the chair thus that it is easy to seen by the subject. Then
instruct the subject to stand when hear the term STAERT, walk streak on the ground,
turn around, walk back to chair and sit down. The timer will started on the term
” STAERT ” and stop when the subject is seated right again in the
chair with her back fully resting on the chair. Normal healthy middle-aged
people usually do the test in ten seconds or less and the very weak with poor
mobility middle-aged people, may take 2 minutes or more.

Significance of the study:

If the findings of the study show a
relationship between muscle strength and Balance, educational courses will be
sugested to be delivered to educate healthy women the importance of
strengthening their lower limb muscles to maitain balnce .


The sample size is 40 participants, therefore,
the findings of this study will be limited and can not be generalized to all
population  in the eastern region of
Saudi Arabia.

Outcome measures:

Muscle Strength: Many tools are
reported in the literature to measure muscle strength such as myometer, sit to
stand ex, maximum isometric leg extension strength, isokinetic dynamometry and
one repetition maximum assessment (1RM). However, hand-held dynamometer will be
used in this study because it is small, accurate, time efficient, provides a
quantified measurement of force and is relatively inexpensive compared with
isokinetic dynamometry. It is easy to use and has a convenient size which may
justify widespread clinical use) M 
2014; Timothy  Stark  BS, 2011(.

Procedure of data collection: Participants will be instructed to
come to the university’s Lab. Researcher will do the measurements in approximately 20
minutes, with 5 minutes rest between each test. Soft drinks will be provided
and transportation will be available for the subjects.

Ethical considerations: the ethical approval will be take from the
ethics community within Imam Abdulrahman bin Faisal University. A participation
information sheet will be distributed among healthy middle-aged women
explaining all phases of the study. All participants will sign a consent form
before commencing data collection. Safety of all participants will be ensured
throughout the study. Data will be kept in hard paper format in secure storage
and in digital files, saved on desktop computers accessible only to the primary
investigator and the research team.   

Data analysis:

 Statistical analysis will be carried out using
SPSS software. Participants’ characteristics will be analyzed using descriptive
analysis. Pearsons’ correlation coefficient test will be used to investigate
the relationship between muscle strength and balance. In addition, it will be
used to investigate the relationship between participants’ characteristics
(Age, BMI), strength and balance. The Spearman correlation coefficient test
will be used to investigate the relationship between participants’ other
characteristics, muscle strength and balance. The values will be considered
statistically significant at P ? 0.05.



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