The Effects of Sling Exercise Using Vibration on Trunk Muscle Activities of Healthy Adults

J. Phys. Ther. Sci. 25: 1291–1294, 2013

Youngin Choi, MSc, PT1), Hyungkyu K ang, PhD, PT2)* 1) Department

of Physical Therapy, the Graduate School, Hanseo University, Republic of Korea of Physical Therapy, College of Natural Sciences, Kyungnam University: 449 Woryeong-dong, Masanhappo-gu, Changwon-si, Gyeongsangnam-do 631-701, Republic of Korea

2) Department

Abstract. [Purpose] This study compared the effects of sling exercises with and without vibration on the muscular activity of the internal oblique (IO), rectus abdominis (RA), multifidus (MF), and erector spinae (ES) muscles of healthy adults. [Methods] Eleven healthy university students (11 men) with a mean age of 22.8 years were enrolled in this study. Subjects performed supine and prone bridge exercises with the knees flexed using a sling suspension system with and without vibration. The amplitudes of the EMG activities of selected trunk muscles (internal oblique, rectus abdominis, erector spinae, multifidus) were recorded. Two types of exercise conditions were executed in a random sequence for 5 seconds each. The signals detected from the middle 3 seconds (after discarding the signals of the first and the last one seconds) were used in the analysis. A 3-minute break was given after each exercise to minimize muscle fatigue. [Results] During the supine bridge exercise with vibration, the activities of the IO, RA, MF, and ES muscles were significantly higher than those of the supine bridge exercise without vibration. Additionally, during the prone bridge exercise with vibration, the activities of the IO, RA, MF, and ES were significantly higher than those of the prone bridge exercise without vibration. [Conclusion] Sling exercises with vibration improved the trunk muscle activities of healthy adults compared to the sling exercises without vibration. The information presented here is important for clinicians who use lumbar stabilization exercises as an evaluation tool or a rehabilitation exercise. Key words: Sling exercise, Vibration, Trunk muscle (This article was submitted Apr. 8, 2013, and was accepted May 20, 2013)

INTRODUCTION Stabilization exercises are exercise methods that focus on co-contraction of deep trunk muscles and improvement of spinal stability1). Stabilization exercises not only the improve strength and endurance of deep trunk muscles, but also have the effect of maintaining dynamic stability by improving neuromuscular control2). Consequently, they are used in a wide range of rehabilitation therapies for individuals with low back pain3–5). Coordination promotions between local and global muscles are necessary factors of efficient lumbar stabilization6). Activities of a single muscle do not systematically influence trunk stabilization6–9). Therefore, for an adequate level of stability maintenance, integration of local and global muscle is required10, 11). Sling therapy is performed by suspending part of body in a sling12). It was reported that sling therapy has the advantage of facilitating exercise by decreasing the load on the body12, 13). Sling therapy also facilitates neuromuscular control of the extremities14). Vibratory stimulation can improve muscle contraction by stimulating muscle hypertrophy, thereby affecting the muscle spindles15). Type Ia af-


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ferent fibers are co-activated by α-γ motor neurons. They are activated during isometric contraction, and vibratory stimulation improves the strength of the muscular contraction by increasing the firing rate of Type Ia fibers, and the excitability of α motor neuron16). Sling exercise therapy with vibration should improve lumbar stability by increasing trunk muscle activity. However, only a limited number of studies have investigated the effects of sling exercise therapy using vibration on trunk muscles activation. Therefore, this study investigated the effect of sling exercise therapy with and without vibration on trunk muscles, activation and their ratios to elucidate an effective lumbar stabilization training method. SUBJECTS AND METHODS Eleven healthy adults (11 men) were recruited from A university through a leaflet explaining the details of the study. The general characteristics of the subjects are shown in Table 1. Subject inclusion criteria were a normal body weight and no limitation of motion of the hip or knee joints. Subject exclusion criteria were congenital malformation, neurological or orthopedic symptoms, or low back pain. All subjects included in this study were given a complete explanation of the study and voluntarily signed participation consent forms before participating in the experiment. The study was approved by the human research ethics commit-

1292 J. Phys. Ther. Sci. Vol. 25, No. 10, 2013 Table 1. General characteristics of the subjects Subjects (n=11)


Age (years)

Height (cm)

Weight (kg)

11 males

22.83 ± 1.65

173.67 ± 6.86

69.48 ± 14.55

All values are mean±standard deviation (SD)

Table 2. Comparison of trunk muscle activities during supine bridge exercise with and without vibration

IO** RA* MF** ES**

SBE (M ± SD)


11.52 ± 9.25 2.46 ± 1.99 30.05 ± 5.13 24.87 ± 8.02

17.90 ± 12.61 3.78 ± 3.12 36.53 ± 6.05 31.01 ± 8.56

All values are mean±SD. SBE: supine bridge exercise. SBEV: supine bridge exercise with vibration, IO: internal oblique, RA: rectus abdominis, MF: multifidus, ES: erector spinae. * p

The effects of sling exercise using vibration on trunk muscle activities of healthy adults.

[Purpose] This study compared the effects of sling exercises with and without vibration on the muscular activity of the internal oblique (IO), rectus ...
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