Middle Eastern Journal of Disability Studies

Background & Objectives: Hearing impairment is the most common sensory–neurological defect in individuals. Core stability is the motor control and muscle capacity of the central area of the body to maintain stability in various postures and external forces. Total Resistance Exercise (TRE) is often used to improve muscle strength and performance in athletes, the rehabilitation of orthopedic diseases, and prevent muscle weakness. An essential factor in preserving the posture in individuals with hearing impairment is to reduce the level of imbalance. Due to reduced balance in this population and the lack of research on TRE, this study aimed to compare the effects of 8 weeks of suspended training and core stability training on the trunk flexor and extensor muscles endurance in adolescents with hearing impairment.
Methods: This was a quasi–experimental study with a pretest–posttest design. The statistical population of the study included all hearing–impaired students in Bandar Abbas City, Iran. Considering the limited size of the population, 12 students with severe hearing impairment were selected as the statistical sample of the study, whose extent of hearing impairment ranged between 71 dB and 90 dB. These students were purposively selected and divided into two groups of 10 by simple random sampling method, as follows: the group of suspended exercises (n=10; mean±SD age=14.91±1.24 years) and a core stability exercise group (n=10; mean±SD age=14.66±1.23 years). The inclusion criteria of the study were male gender (due to their availability, compared to girls), the age of 12–14 years, and no sports background. The exclusion criterion of the study was not to practice and leave the training sessions. In this study, Biering–Sorenson Test and Sit Ups Test were used before and after 8 weeks of training in the research groups. Experimental group 1 performed a weekly TRX training program and experimental group 2 performed core stability exercises under an instructor for 8 weeks and three 40–min weekly sessions. Then, after completing the training, the posttest phase was performed. Descriptive statistics were used to describe the study variables. Inferential statistics, including the Independent Samples t–test and Dependent Samples t–test, were applied in SPSS‌ to compare the mean scores of the study variables between the study groups. The significance level of the tests was considered 0.05.
Results: The mean±SD pretest and posttest sit–ups in the TRX exercise group equaled 15.67±4.69 and 21.58±6.28 times per minute, respectively. TRX exercises were effective in increasing the sit–ups (p<0.001). The mean±SD pretest and posttest sit–ups in the core stability exercises group were measured as 16.41±4.75 and 23.41±5.45, in sequence. Core stability exercises were effective in increasing the sit–ups (p<0.001). Concerning an increase in the strength of the trunk muscles, there was no significant difference between the exercise methods (p=0.313). Furthermore, the mean±SD Sorenson test time in the TRX exercise group was 33.41±7.9 seconds before the intervention and 39.25±6.62 seconds after the intervention. The method of TRX exercises was effective in increasing the time of trunk flexor muscle endurance (p<0.001). The mean Biering–Sorenson Test time in the core stability group at pretest and posttest was 31.58±9.25 seconds and 37.75±6.95 seconds, respectively. The core stability exercises effectively increased the time of trunk flexor muscle endurance (p<0.001). The exercise methods' performance respecting increasing the time of the trunk flexor muscle endurance revealed no significant difference between the research methods (p=0.251). 
Conclusion: According to the present study findings, participation in 8 weeks of core stability exercises and suspension exercises increased the endurance of trunk flexor and extensor muscles in hearing–impaired adolescents; there was no significant difference between the exercise groups.