1 INTRODUCTION:

Push-ups are an exercise that is effective in shoulder rehabilitation, and health¹. It is commonly used due to its effectiveness of either strengthening or targeting activation of muscles that act on the scapular and humerus². Push-up exercise is due to its ability to target muscles that are important for scapular kinematics, such as the serratus anterior³. When using push-ups in either strength training or rehabilitation settings the position of the hands may alter muscle activation and scapular kinematics⁴.

According to a recent study push up variations include TPU, modified push up, WPU, and any one of those on a stable or unstable surface⁵. This intervention by the hand position to include internal/external rotation, wide, narrow, standard. Push up exercise position has been a variety of studies. Various push up position has an effect on muscle activation of the muscles of the shoulder. Muscles involved during a push up include the serratus anterior, upper trapezius, lower trapezius, pectoralis major, triceps brachii, anterior deltoid, posterior deltoid and biceps brachii⁶.

According to the study on the push up exercise Sandhu at el. (2008) presented anterior deltoid has have a greater amount of activation on an unstable surface compared to a stable surface⁷. Hardwick et al. (2006) repor- ted that serratus anterior has a large amount of activation in all push up conditions, while different surfaces affect the part of the serratus anterior that is most active⁸. According to previous study in push up exercise with TPU, modified push up, WPU, and stable or unstable surface forms, muscular activities were examined by interventing the rotation of the position of hands in various positions such as internal/external rotation, wide, narrow, standard, etc. However, every dissertation compared the muscular activities of the position of supported hands intervention in static form, therefore, research focused on various exercises on each muscle and intensification of exercise level was not sufficient.

Due to its relative lack of bony constraints the shoulder has the largest range of motion of any joint in the human body allowing positioning of the hand in many functional positions. Therefore, a fine balance between mobility and stability is required to sustain the optimal function of the shoulder joint⁹. Additionally, Veegera and Helma (2007) presented that during dynamic shoulder exercise there is an interaction between physiological and biomechanical factors, including changes in the moment arm of force and gravity and muscle length and the position of the joint contact surfaces at different joint angles¹⁰. However, Anders et al. (2011) presented that static shoulder exercise did not show factors of when dynamic shoulder exercise was applied¹¹.

The upper quarter Y-balance test has been proposed as a closed kinetic chain (CKC) assessment of upper quarter mobility and stability using a functional testing device¹². It is appears to be most related to dynamic type of tests involving core stability and upper extremity performance. It is mostly baseball players, softball players, swimmers, athletes, etc of the target has been used¹³, the subject performed maximal effort reaches with the free hand in three directions (lateral, superomedial, and inferomedial) named in relation to the stationary hand¹⁴. The distance reached in each direction was recorded to have been used in relation to the stability of the shoulder joint assessment of muscle strength flexibility and proprioception¹⁵.

In previous studies, upper quarter Y-balance test was applied to examine the muscular strength, flexibility, proprioception regarding the stability of shoulder joint but it is necessary to examine the effectiveness of existing push up exercise of static form as shoulder exercise of dynamic form by using upper quarter Y-balance exercise after combining the upper quarter Y-balance test with push up exercise.

The objective of this study is first to examine the muscular activity in prone position and standing position by intervening the three directionalities of upper quarter Y-balance exercise in TPU form and WPU. Second, to examine the muscular activities regarding directionalities of interventions by intervening the dynamic form. Based on this, this research attempted to suggest the clinical guideline of proper application of upper quarter Y-balance.

2. MATERIALS AND METHODS:

This research conducted experiment of healthy 34 Individuals of male and female who are attending S university in Asan, Chungcheongnam-do after individuals are well informed and agreed with content and objective of the research. The duration of the experiment was from May 31st of 2016 to June 17th of 2016. 17 female individuals and 17 male individuals were selected as participants. Physical characteristics of participants were that age was 20.82 ± 1.22, height was 168.58 ± 5.89, and weight was 63.29 ± 9.08. Selection criteria of participants were that each of individuals did not have medical or surgical history within 3months, shoulder fracture in recent, history of cardiopulmonary disease at all, neurological damage such as radiating pain in upper arm area and hypoesthesia, osteoporosis, and history of therapeutic exercise due to instability of shoulder. Also individuals who has participation rate of lower than 80 percent were exempted. This research obtained approval of clinical test judging committee of Sunmoon University (SM-201609-035-1).

2.2. Measurement Method:

In this experiment upper quarter Y-balance pad with setting of +60 degrees as superomedial direction, and -60 degrees as inferomedial direction when lateral direction was set to 0 was used to present three different directionalities of upper quarter Y-balance exercise which are lateral, superomedial, and inferomedial. In order to monitor the muscular activities of serratus anterior, upper trapezius, pectoralis major, triceps brachii, anterior deltoid, posterior deltoid and biceps brachii, EMG (Zero WIRE EMG, EMG OQUS100, Italy, 2009) was used. Previous to the experiment to lower the skin resistance on the area where EMG pads were attached on shaving and wearing sleeveless shirt were suggested. EMG analog signals collected from 7 different channels were sent to MP150 system to be converted to digital signals then they were analyzed and processed with sEMG software myoresearch 1.06.44 software on com- puter. Sampling rate of signals were set to 1000Hz and frequency bandwidth minimized noise by using 20~500Hz measurement frequency range.

Muscle activity was considered as Root mean square (RMS) and after measuring the maximum muscular strength of subjects in isometric form statistical level of significance was set to p<.05 with MVIC% values. Also, when measuring the MVIC% we required them to give maximum power for 3seconds and repeat the set 3 times.

2.3. Experiment Procedures:

Test subject group of this research was measured as single subject. Previous to the experiment by practicing exercise motion it was confirmed that if they perform the proper motion. The experiment was conducted with random order. In order to identify the accurate muscle activity of each motion experiment was conducted after maximum muscular strength of 7 different muscles of each subject was measured. During the measurement it was identified if signals are correctly shown in the computer monitor before the experiment was started. Maximum distance of test subjects in three different directions of lateral, superomedial, and inferomedial were measured when test subjects were in TPU form and WPU form by using upper quarter Y-balance pad. In TPU form, the test subject spread the legs as wide as shoulder width and put measured arm perpendicular to acromion and the other arm next to measured arm for initial position[Figure 1].

In WPU form, test subject spread the legs as wide as shoulder width and did 90 degree flexion with shoulder to be measured[Figure 2]. In two forms, muscle activity of serratus anterior, upper trapezius, pectoralis major, triceps brachii, anterior deltoid, posterior deltoid and biceps brachii regarding lateral, superomedial, and inferormediall directions for three second. At this moment, hand of test subjects must be attached from the ground and velocity of unmeasured arm must be constant.

2.4. Statistical analysis:

This research compared within upper quarter Y-balance exercises using paired T test to verify the effect of each type of exercise program and intervention. And they were compared in two different push up forms using one-way repeated ANOVA and if significance was recognized then posteriori test of Bonfferoni was conducted. Also, analysis of research results carried out with statistic process of every measurement value using SPSS 18.0 version. Software used/ SD/level of significance, repeatability etc.

3. RESULTS AND DISCUSSION:

WPU and WPU posture of lateral direction result showed significant difference upper trapezius and the triceps brachii. Serratus anterior, pectoralis major, anterior deltoid, posterior deltoid and biceps brachii did not show a significant difference in lateral direction (p<.05). TPU and WPU posture of superomedial direction result showed significant difference anterior deltoid and serratus anterior. But, upper trapezius, pecto- ralis major, triceps brachii, posterior deltoid and biceps brachii did not show a significant difference in superomedial direction (p<.05). Finally, TPU and WPU posture of inferomedial direction result showed significant difference upper trapezius and serratus anterior. Pectoralis major, triceps brachii, anterior deltoid, posterior deltoid and biceps brachii did not show a significant difference in inferomedial direction (p<.05).

The TPU position posterior deltoid, biceps brachii showed significant difference in between three directions of the lateral, superomedial and inferomedial. However, it did not show a signifi- cant difference serratus anterior, upper trapezius,- pectoralis major, triceps brachii and anterior deltoid in three directions. There was significant difference shown in three different directions of lateral/superomedial, lateral/inferomedial, superomedial/inferomedial in posterior deltoid. And biceps brachii was significant difference in lateral /superomedial, lateral/inferomedial directions (p<.05) [Figure 3].

The WPU position posterior deltoid and triceps brachii showed significant difference in between three directions of the lateral, superomedial and inferomedial. However, it did not show a significant difference serratus anterior, upper trapezius, pectoralis major, biceps brachii and anterior deltoid in three directions. There was significant difference shown in three different directions of lateral /superomedial, lateral/inferome- dial in posterior deltoid. And in triceps brachii was significant difference in lateral /superomedial, lateral/inferomedial directions (p<.05) [Figure 4].

Figure 3. Traditional push up

Figure 4. Wall push up

In this research, in TPU form and WPU form intervening three different directionalities of upper quarter Y-balance muscle activity on each direction of prone position and standing position and muscle activity of directionalities were compared by intervening them in dynamic forms.

However, according to previous dissertations in push up exercise with TPU, modified push up, WPU and stable or unstable surface forms, muscular activities were examined by intervening the rotation of the position of hands in various positions such as internal/external rotation, wide, narrow, standard, etc. Various previous dissertations attempted to examine the shoulder muscle activity with various interventions on various positions such as push up exercise TPU, modified push up, WPU, and stable or unstable surface¹⁶. However, most of dissertation compared the muscular activities of the position of supported hands intervention in static form therefore, research focused on various exercises on each muscle and intensification of exercise level was not sufficient. This dissertation has its significance on suggesting exercising method with selective exercise motion and intensity of shoulder stability muscle as a result of attempting to examine the muscle activities on dynamic situation with intervention of three directionalities of upper quarter Y-balance in TPU form and WPU form.

Ludewig and Cook (2000) presented the importance of upper trapezius and serratus anterior through push up exercise¹⁷. The serratus anterior and the upper trapezius are the main stabilizer muscles of the scapulothoracic joint¹⁸. These muscles act in a synergic action that allows for an appropriate scapulothoracic rhythm. This is essential to the maintenance of the length tension relation of scapulohumeral muscles and to the normal biomechanics of the shoulder during humerus elevation movements¹⁹. Martins et al. (2008) presented that there is significant difference in serratus anterior and upper trapezius when intervention of stable and unstable were given to TPU form and WPU form²⁰. In this research with dynamic intervention in TPU form and WPU, when hand position of three directions were additionally mediated in two different push up forms for lateral directions, triceps brachii and upper trapezius for superomedial directions anterior deltoid and serratus anterior lastly for inferomedial directions, upper trapezius and serratus anterior showed significant differences. With this result and that upper quarter Y-balance exercise with dynamic intervention also showed muscle activation on serratus anterior and upper trapezius the effectiveness of upper quarter Y-balance exercise combined with push up exercise was verified.

According to the result of this research inferomedial, superomedial, lateral directions of upper quarter Y-balance exercise on TPU required more muscle activities than it on WPU. The base of support for TPU form is bigger than it of WPU form meaning that it is expected to require more strength and it can support performing a push up against gravity may be unsuitable in the initial stages of a rehabilitation program of Yoo (2015)²¹. Also, Veegera and Helma (2007) pres- ented that imbalance and weakness of the serratus anterior and upper trapezius force couple have been described in patients with shoulder dysfunction¹⁰, and in upper quarter Y-balance exercise of this research can suggest selective muscular exercise and rehabilitation protocol on imbalance of serratus anterior and upper trapezius with different directionalities.

When it comes to comparison of directional intervention in TPU form and WPU form two forms have different muscles with muscle activation. The TPU position posterior deltoid, biceps brachii showed significant difference, WPU position posterior deltoid and triceps brachii showed significant difference. In push up work out that uses CKC exercise unlike open kinetic chain (OKC) work out that primary muscle are applied in concentric way, it is applied eccentric way that it stabilizes damaged joint. TPU is prone posture that trunk is going against the gravity and humerus is dyskinetic form. When following these characteristics are applied to upper quarter Y-balance exercise according to the trait of CKC on shoulder rather than general anterior deltoid, posterior deltoid showed muscle activity since it is form with trunk going against the gravity. In case of humerus with dyskinetic form showed the muscle activity of biceps brachii. Since it is WPU supine posture trunk is in kinetic form and humerus is dyskinetic form. It was shown that if this is applied to the character of CKC due to the dyskinetic character of humerus triceps brachii and posterior deltoid are showing muscle activity. However, since the kinetic form of trunk does not affect directly on shoulder that there is no other muscle with activity shown through trunk.

When muscle activities on three different directions of TPU and WPU with directional comparison were examined both in the TPU biceps brachii and in the WPU posterior deltoid, triceps brachii required highest muscle activities from inferomedial direction. Thus, direction of center of gravity (COG) is different depending on the direction of hand when the direction of hand was in inferomedial direction COG is resulting shoulder requires more strength in medial form. However, unlike other muscles in TPU form only posterior deltoid required the biggest strength in superomedial due to the fact that posterior deltoid has bigger load on shoulder with traditional push up that trunk going against the gravity and with CKC principle rather than COG which shows highest muscle activity in superomedial direction. Thus, this research has its significance on that using eccentric contraction of antagonistic muscle of CKC exercies can vary with stability of shoulder and COG. Additionally, Veegera and Hlema (2007) reported that dynamic exercise and static exercise on shoulder can imp- rove muscle coordination and proprioception can accept information on muscle spindle and golgi tendon organs resulting increase of stability of shoulder ²². In other words, during the push up exercise if upper quarter Y-balance exercise of dynamic form and static form together, it is anticipated to have bigger effect on increase of shoulder stability.

Limit of this research would be that since it is conducted with healthy individuals aged in their 20s it is limited to be interpreted with general- ization to individuals of other ages and patients. Also, while maximum muscular strength was measured researcher was giving resistance with hands and it could be slightly different to each test subjects that there might be error on equity of results. This research attempted to examine the effectiveness of push up exercise in dynamic forms as upper quarter Y-balance exercise however, existing static push up exercises were not tested together that precise comparison of two was not obtained. In the future, it is necessary to conduct a research comparing dynamic and static push up exercises.

4. CONCLUSION:

This study knew when comparison TPU form and WPU form of directional intervention by CKC exercise characteristic due to antagonist muscle activation. The TPU position posterior deltoid, biceps brachii showed significant difference, WPU position posterior deltoid and triceps brachii showed significant difference. When muscle activities on three different directions of TPU and WPU with directional comparison required highest muscle activities from inferomedial direction. Because direction of center of gravity (COG) is different depending on the direction of hand when the direction of hand was in inferomedial direction COG is resulting shoulder requires more strength in medial form. Therefore, it was know that upper quarter Y-balance exercise the help of the stabilization shoulder muscles.

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Received on 22.06.2017 Modified on 29.06.2017

Research J. Pharm. and Tech. 2017; 10(7): 2279-2284.

DOI: 10.5958/0974-360X.2017.00404.8

Activation of selected Shoulder Muscle according to Posture during upper quarter Y Balance Exercise