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Effects of Isometric Upper Limb Contraction on Trunk and Leg Muscles During Sit-to-stand Activity in Healthy Elderly Females

Authors:
J Korean Soc Phys Med, 2017; 12(1): 61-66
http://dx.doi.org/10.13066/kspm.2017.12.1.61
Online ISSN:
Print ISSN:
2287-7215
1975-311X
Research Article Open Access
Effects of Isometric Upper Limb Contraction on Trunk and Leg Muscles During
Sit-to-stand Activity in Healthy Elderly Females
Eun-Mi Jang, PhD, PT
Jae-Seop Oh, PhD, PT
1
Mi-Hyun Kim, PhD, PT
1
Dept. of Rehabilitation Science, Graduate School, Inje University
1
Dept. of Physical Therapy, Inje University
Received: October 21, 2016 / Revised: October 31, 2016 / Accepted: November 26, 2016
2017 J Korean Soc Phys Med
| Abstract |1)
PURPOS E:
The purpose of this study was to investigate
the effects of isometric upper limb contraction on the trunk
and lower extremity muscles during the sit-to-stand activity
in elderly females.
METHODS:
Eighteen healthy elderly females performed
three directional isometric upper extremity contractions
(flexion, extension, and horizontal abduction movements)
using an elastic band during sit-to-stand activity. Electromy-
ography signals were collected from the internal oblique,
erector spinae, rectus femoris, and biceps femoris muscles.
RESU LTS:
Internal oblique activity was greater in
bilateral shoulder flexion and bilateral shoulder horizontal
abduction than in neutral position (p<.05). Erector spinae and
rectus femoris muscle activities in bilateral shoulder flexion
was greater than in neutral position and bilateral shoulder
extension (p<.05). Biceps femoris activity was significantly
greater in bilateral shoulder flexion than in bilateral shoulder
extension and horizontal abduction, and in neutral position
compared to bilateral shoulder extension (p<.05).
†Corresponding Author : kmh211@inje.ac.kr
This is an Open Access article distributed under the terms of
the Creative Commons Attribution Non-Commercial License
(http://creativecommons.org/licenses/by-nc/3.0) which permits
unrestricted non-commercial use, distribution, and reproduction
in any medium, provided the original work is properly cited.
CONCLU SION:
These results suggest that incorporating
isometric upper limb contraction may be beneficial for
enhancing the contribution of trunk and lower extremity muscle
activities to trunk stabilization during sit-to-stand activity.
Therefore, isometric upper limb contraction during sit-to-stand
tasks, especially in flexion, may be used to elicit contraction of
the lumbopelvic region muscles within a tolerable range, for
developing endurance and strength in the elderly.
Key Words:
Isometric contraction, Leg muscle, Sit-to-stand,
Trunk muscle, Upper extremity
. Introduction
The ability to rise from a seated position, otherwise
known as sit-to-stand activity (STS), is essential for postural
maintenance and controlled and coordinated movement
(Park, 2002). Safe execution of STS is a prerequisite for
activities such as walking and stair climbing (Papa and
Cappozzo, 2000).
Age-related declines in lower limb strength and balance
and sensory systems have independently been shown to
impair safe and efficient execution of STS in older adults
(Lord et al., 2002; Schenkman et al., 1996). In elderly
women in particular, decreased muscle strength of the lower
extremities occurs more quickly than in elderly men,
62 | J Korean Soc Phys Med Vol. 12, No. 1
reducing balance and gait ability (Park and Yoon, 2009).
Standing up require greater muscle strength, range of
motion and a peak joint moment than walking and stair
climbing. It also requires the balance ability to translate
the body mass forward and upward from a relatively stable
sitting position to the feet. Because of these mechanical
demands, elderly people may experience difficulty when
standing from a chair (Carr and Shepherd, 2011; Yoshioka
et al., 2009). It was found that older adults exhibited a
longer execution time than younger adults for executing
STS possibly due to the poorer leg muscle strength in
elderly adults (Yamada and Demura, 2009).
Thus the balance training and muscle strengthening
exercise may be required to successful STS performance
in elderly people (Kim et al., 2010). Previous studies have
been suggested that trunk and hip muscles may be affected
by loading induced from upper- and lower-limb movement
(Arokoski et al., 2001; Park and Yoon, 2009; Tarnanen
et al., 2008). Arokoski et al. (2001) found that the activation
patterns of the abdominal muscles were affected by the
direction of restricted upper-limb movements. Other
researchers have shown that the direction of resistance on
the upper limb could affect the activation patterns of the
abdominal muscles (Lee et al., 2012). However, these
exercises were performed in a static posture only, such
as a standing or sitting position. There are no studies on
effects of the resistance direction of upper extremity on
trunk and leg muscles during a dynamic movement such
as STS. Therefore, the purpose of this study was to quantify
and compare how isometric contractions of upper extremity
affect trunk and lower extremity electromyography activity
during STS in healthy old adults.
. Methods
1. Subjects
We recruited 18 healthy elderly women volunteers from
a community dwelling in Gimhae city. The mean age of
the subjects was 68 ± 1.97 years (mean ± SD), mean height
was 154.72 ± 4.21 cm, and mean body weigh was 54.61
± 6.84 kg. The Inje University Faculty of Health Science
Human Ethics Committee granted approval for this study,
and all subjects provided written informed consent prior
to participation.
2. Instrumentation
Surface EMG signals were recorded using four
pre-amplified (gain: 1,000) active surface electrodes (Model
DE-2.3, Delsys Inc., Wellesley, MA, USA) with surface
electrodes fixed at an inter-electrode distance of 10 mm.
The sampling rate was 1,000 Hz; the band-pass filter was
20
450 Hz. Raw data for the four muscles were processed
into root-means square (RMS) data.
The electrodes were positioned on four sites on the right
side of the subjects’ bodies: internal oblique (IO), erector
spinae (ES), rectus femoris (RF), and biceps femoris (BF)
muscles. For normalization of the EMG signal, subjects
were asked to perform a maximum voluntary isometric
contraction (MVIC) maneuver for 5s. The EMG data
expressed the entire STS task as a percentage of maximum
voluntary isometric contraction (%MVIC). One
infrared-retro reflective marker was placed on the superior
aspects of the scapular acromion process to define the start
and end positions of the STS (Vicon 512, Oxford Metrics
Group, UK).
3. Procedures
Subjects were instructed to sit with an upright trunk
posture on a height-adjustable bed without back support
and with feet flat on the floor. The hip, knee, and ankle
joints were positioned at 90
flexion, and the feet were
positioned shoulder-width apart with the toes pointing
directly forward. The poles were placed directly in front
of (extension condition) or behind (flexion condition) the
trunk bilaterally at a distance of 1m, and the subject’s
shoulder height was measured to determine the fixed axis
for the elastic band. A blue elastic therapeutic band
Effects of Isometric Upper Limb Contraction on Trunk and Leg Muscles During Sit-to-stand Activity in Healthy Elderly Females
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63
Muscles Condition p-values
NExtH-AbdFlex
IO 35.76±13.47a38.03±14.34 41.76±14.0143.15±15.13.002*
ES 50.64±15.54 44.28±14.93 47.50±13.86 56.99±14.64,.000*
RF 36.93±15.27 38.39±15.09 38.47±15.55 42.67±14.64,.037*
BF 36.86±18.52 31.62±17.9333.14±18.93 38.99±20.23,‡‡ .002*
Abbreviations: MVIC, maximum voluntary isometric contraction; N, neutral; Ext, extension; H-Abd, horizontal abduction;
Flex, flexion; IO, internal oblique; ES, erector spinae; RF, rectus femoris; BF, biceps femoris.
aMean±SD.
* p<. 05.
Significantly different compared to the N
Significantly different compared to the Ext
‡‡ Significantly different compared to the H-Abd
Table 1. The differences of muscle activities (%MVIC) during STS with isometric upper limb contraction (N=18)
(TheraBand, Hygenic Corporation, USA) was used to
regulate resistance in the upper limb. All subjects grasped
the elastic band 50cm from the fixed axis with both arms
so that same resistance was applied to the upper limb. A
goniometer was used to determine the shoulder movement
range (from neutral position to 40° flexion, neutral position
to 40° extension, and from 90° flexion to 90° horizontal
abduction), and then a target bar was placed in front (flexion
condition) or behind (extension condition) of subjects to
control shoulder movement (Lee at al., 2012).
Each subject was instructed to extend or flex both
shoulders with full extension of the elbow joint during
the entire STS motion and then to hold a standing position
for 3s. Horizontal abduction started at 90
flexion of the
shoulder. Subjects were asked to perform horizontal
abduction with both arms with full extension of the elbow
joint during the entire STS task and then to hold a standing
position for 3s. EMG data for the four muscles were
collected for each subject during the entire STS task.
Four types of STS experimental tasks were performed
in random order: 1) Neutral STS (N), 2) STS with isometric
upper limb extension (Ext), 3) STS with isometric upper
limb horizontal abduction (H-Abd), and 4) STS with
isometric upper limb flexion (Flex). To ensure sufficient
practice and adherence to correct patterns, these strategies
were practiced repeatedly until the physician qualified the
subject before entering the test. STS was performed at a
self-paced comfortable speed.
4. Statistical analysis
Significant differences among the four conditions (neutral,
extension, horizontal abduction, and flexion) were examined
using a repeated-measures analysis of variance (ANOVA).
If a significant difference was found, post hoc Fisher’s Least
Significant Difference (LSD) correction was performed to
determine differences in pair-wise comparison. Data were
analyzed using the SPSS software (ver. 18.0, Chicago, IL,
USA), and the significance level was set at p<.05.
. Results
The mean and standard deviations of %MVIC for each
condition are presented in Table 1. EMG activity of IO
was significantly greater for the Flex condition and the
H-Abd condition compared to the N condition, and for
Flex condition compared to the Ext condition (p<.05,
respectively). EMG activity of ES was significantly greater
for the Flex condition compared to N, Ext, H-Abd conditions
(p<.05), and N condition compared to Ext condition (p<.05).
64 | J Korean Soc Phys Med Vol. 12, No. 1
EMG activity of RF was significantly greater for the Flex
condition compared to N and Ext conditions (p<.05), and
EMG activity of BF was significantly greater for the Flex
condition compared to Ext and H-Abd condition, and for
N condition compared to Ext condition (p<.05, respectively).
. Discussion
The goal of this study was to investigate
electromyography activities of trunk and lower limb
muscles during STS with isometric upper limb contraction.
Overall, the result of this study was increased muscle
activities of the IO, ES, RF, and BF in Flex condition
compared to N, Ext, and H-Abd conditions. Our study was
the first to examine trunk and lower extremity muscle
activation on isometric upper limb contractions during an
STS activity.
Large movements are usually produced in both the hip
joint and the knee joint during STS, and thus any problems
with muscle weakness or postural instability will lead to
the use of alternative strategies (Corcos et al., 1996; Inkster
and Eng, 2004). Using momentum in any transfer technique
is a valuable option to any person who exhibits muscle
weakness or other problems in standing up (Nuzik et al.,
1986). This is important, as these interventions are targeted
toward older adults and those with pathologies.
According to previous findings (Arokoski et al., 2001;
Park and Yoon, 2009; Tarnanen et al., 2008) that suggested
that trunk and hip muscles may be affected by loading
induced from upper and lower limb movement, we used
the extra loading provided by applying isometric upper
limb contractions such as arm extension, horizontal
abduction, and flexion resistance during STS movement.
In this study, IO and RF muscles were activated more
during the STS with isometric upper limb contraction than
during STS alone. These results support that loading
resistance induced from limb movement requires an
additional stabilization effort to keep trunk and hip stability
at an optimal level (Park and Yoon, 2009).
In this study, we also investigated the effects of
resistance direction using an elastic band on trunk and hip
muscle activities during STS with isometric upper limb
contraction. The results indicate that the direction of
resistance on the upper limb appeared to affect the
activation patterns of the IO, ES, RF, and BF muscles.
When a limb is moved, the body reacts with forces that
are equal in magnitude, but in the opposite direction to
the limb movement. Tarnanen et al. (2008) reported that
bilateral shoulder extension produced the greatest activity
in the abdominal muscles. During bilateral shoulder
extension, a long lever arm and the upper-body muscles
are able to produce sufficient torque to load the trunk
muscles. Arokoski et al. (2001) found that simultaneous
resisted upper extremity extension while standing caused
high abdominal muscle activity, whereas resisted upper
extremity flexion while standing caused high back muscle
activity. As in previous studies, the current study revealed
that EMG activities of back extensor muscle such as ES
and BF muscle were significantly higher in Flex than in
Ext and H-Abd during the STS movement. However, STS
with the Flex condition led to increased activation of IO
and RF muscle as well as ES and BF muscles to control
against the force of gravity and provide more momentum
for balance and stability than the Ext condition.
These results could be affected by the experimental
posture. The previous studies were performed in a static
position, such as standing or sitting, whereas in this study
the STS movement required forward and upward movement
of the body mass from a base of support provided by the
chair and the feet to the feet only, while maintaining balance
(Shepherd and Gentile, 1994). A therapeutic band used
in this experiment was able to resist a counter force in
the opposite direction. During STS with Ext and H-Abd
conditions, the therapeutic band was fixed to the front side
of the body, and therefore the band tension was exerted
Effects of Isometric Upper Limb Contraction on Trunk and Leg Muscles During Sit-to-stand Activity in Healthy Elderly Females
|
65
in the same direction toward the body mass transfer that
might act to support the STS activity. However, during
STS with the Flex condition, the fixed band was at the
back of the body to provide resistance against moving the
body mass forward and to possibly induce co-activation
of the IO, RF, ES, and BF muscles It has been suggested
that co-contraction could be a control mechanism to
maintain postural stability, or to recover from perturbations
or the decrease in force and torque production capability
that result from aging (Benjuya et al., 2004; Cenciarini
et al., 2010). Previous researchers suggested that the elderly
tend to increase stability by stiffening the trunk or legs
to compensate for impaired neuromotor functions and
decreased muscle strength. In the elderly, this phenomenon
elevates antagonist muscle activity, which in turn increases
muscle coactivity (Izquierdo et al., 1999). Elevated muscle
co-activation increases joint stiffness; hence, joint stability
is also increased in the lower extremities (Baratta et al.,
1988). During the STS with isometric arm Flex condition,
most subjects appeared to respond with strong co-
contractions of trunk and lower extremity muscles.
Our results therefore suggest that including isometric
upper limb contraction may be beneficial for enhancing
the contribution of trunk and hip muscle activity to trunk
stabilization during STS movements. Our findings also
support previous studies that have indicated that isometric
upper limb contraction are beneficial for reinforcing the
activity of the trunk and hip muscles (Saliba et al., 2010).
Therefore, it can be supposed that isometric upper limb
contraction during STS activity, especially the Flex condition,
may be used to elicit a contraction of the lumbopelvic
region muscles within a tolerable range for developing
endurance and strength in the elderly for successful STS
activity. However, it should be taken into account that
muscle activation may be influenced by the resistance
intensity as well as the resistance direction and posture.
This study was limited in several respects. First, the
present study did not measure arm muscles that act directly
on the movement. Second, we did not control of resistance
amount by applying in the individually. Further studies
are needed to measure the strength of the arm muscles
by an objective method and to investigate whether these
results have implications for patient rehabilitation.
. Conclusion
This study investigated the effect of the resistance
direction of upper limb on trunk and lower extremity muscle
activity during STS. With isometric upper limb Flex
condition, most subjects appeared to respond during STS
with strong co-contractions of trunk and lower extremity
muscles. The STS activity with isometric upper limb Flex
condition may have better prepared the subjects for higher
skilled muscular responses to destabilizing forces when
performed independently from STS activity. These results
will be helpful in developing strategies for successful STS
task performance in training programs for older women
with muscle weakness. Further studies are needed to
measure the control of resistance amount by applying in
the individually. Measuring strength of the upper and lower
limb muscles by an objective method and investigating
whether these results have implications for the rehabilitation
of patients is also a topic for further research.
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Objectives: To assess the paraspinal and abdominal muscle activities during different therapeutic exercises and to study how load increment produced by varying limb movements and trunk positions could affect these muscle activities. Design: A cross-sectional study comparing muscle activities between men and women. Setting: Rehabilitation clinic in university hospital. Participants: Twenty-four healthy volunteers (14 women, 10 men) aged 21 to 39 years. Interventions: Subjects performed 16 different therapeutic exercises commonly used to treat low back pain. Main outcome measures: Surface electromyography was recorded from the paraspinal (T9, L5) and abdominal (rectus abdominis, obliquus externus) muscles during these exercises. Average electromyographic amplitudes obtained during the exercises were normalized to the amplitude in maximal voluntary contraction (% MVC) to produce interindividually comparable muscle activity assessments. Results: Mean average normalized electromyographic amplitudes (% MVC) of the exercises were below 50% MVC. At L5 level, the multifidus muscle activities were significantly higher (p <.05) in women than in men, whereas no significant difference was found at T9 level. Similarly, rectus abdominis and obliquus externus activities were significantly higher (p <.001, p <.05) in women than in men. Load increment in hands or unbalanced trunk and limb movements produced higher paraspinal and abdominal muscle activities (p <.05). Conclusions: Simple therapeutic exercises are effective in activating both abdominal and paraspinal muscles. By changing limb and trunk positions or unbalancing trunk movements, it is possible to increase trunk muscle activities. Women were better able to activate their stabilizing trunk muscles than men; but it is also possible that men, having a much higher degree of strength on maximal contraction, only need to activate a smaller amount of that maximum to perform a similar activity.
Article
The objective of this study was to quantify the coacti vation patterns of the knee flexor and extensor muscles as part of continued efforts to identify the role of the antagonist muscles in maintaining joint stability. The simultaneous EMG from the flexor and extensor muscles of the knee were recorded during maximal effort, slow isokinetic contractions (15 deg/sec) on the plane parallel to the ground to eliminate the effect of gravity. The processed EMG from the antagonist mus cle was normalized with respect to its EMG as agonist at maximal effort for each joint angle. The plots of normalized antagonist EMG versus joint angle for each muscle group were shown to relate inversely to their moment arm variations over the joint range of motion. Additional calculations demonstrated that the antago nist exerts nearly constant opposing torque throughout joint range of motion. Comparison of data recorded from normal healthy subjects with that of high perform ance athletes with hypertrophied quadriceps demon strated strong inhibitory effects on the hamstrings coac tivations. Athletes who routinely exercise their ham strings, however, had a coactivation response similar to that of normal subjects. We concluded that coactivation of the antagonist is necessary to aid the ligaments in maintaining joint stability, equalizing the articular surface pressure dis tribution, and regulating the joint's mechanical imped ance. The reduced coactivation pattern of the unexer cised antagonist to a hypertrophied muscle increases the risk of ligamentous damage, as well as demon strates the adaptive properties of the antagonist muscle in response to exercise. It was also concluded that reduced risk of knee injuries in high performance ath letes with muscular imbalance could result from com plementary resistive exercise of the antagonist muscle.