1. Background
Children with disabilities, being a minority in the society, their level of physical activity and fitness was lacking concern, either by the disabilities themselves or society. Government statistics, in the year of 2014 - 2015, has revealed that within the almost 900 leisure-time physical activity programmes or fun-day organized or co-organized by the Government of the Hong Kong Special Administrative Region (HKSAR) Leisure and Cultural Services Department, only 13 of them were with people with physical disabilities; while only 2 were for children with special needs, which include any kind of disabilities (1). Researchers found out that children with physical disabilities spent most of their time, either at school or at home, and only tend to be more engaged in walking during free time (2); thus being seen as physically inactive (3, 4). Importantly, a disabled person with inadequate physical fitness would have a higher risk of developing cardiovascular diseases and metabolic syndromes, such as heart disease, diabetes, stroke or other health problems (5, 6); as well as being obese and suffering from mental health issues (7-12). And yet, children and adolescents with any form of disabilities were more likely to be inactive and had poorer physical fitness than typically developed children (13). The Dutch’s physical activity report card on youth with disabilities reported that only 26% of the physically disabled children in special education school did participate in sports regularly compared to over 70% in non-disabled youth (14). Therefore, the low level of physical activity engagement and fitness of children with disabilities were associated with inferior health status, in both physical and mental health (4, 15). It can be known that there were various factors leading to the lack of physical activity and poor fitness of children and adolescents with disabilities; for instance, lack of assistance from caregivers, lack of physical activity (PA) opportunities, concern for the children’s safety, lack of professional teacher training, insufficient facilities at school for disabilities or other socio-environmental factors (16).
Schools are considered as an essential setting for students’ health-promotion and education (4, 9, 17). Local research has also proved that the active behaviour of children with disabilities was being more encouraged under structured activities with teachers’ supervision (2). However, the HKSAR government-commissioned consultancy study (1) demonstrated that the physical activity participation opportunities for children with disabilities varied from school to school. Hong Kong research has only indicated significant results in the physical fitness-and-activity intensity relationships within children with intellectual disability and social development problems but not children with physical disabilities (PD) (4). Schools for physical disabilities showed concern towards the decrease in sports courses’ variety and availability offered by related organizations specialized for them (1); which may result in further physical inactivity and physical health issues within children with physical disabilities (18). Therefore, it is critical to provide more PA opportunities to people with physical disabilities.
1.1. Sitting Light Volleyball
Among different types of physical activity, light volleyball was found to enhance older adults’ physical and psychological health (19). The light volleyball ball is around 20 cm bigger in circumference and 100 g lighter in weight than that of traditional volleyball; thus it enables travel in the air at a lower velocity and for a longer time. The development of light volleyball was aimed at providing another choice of sport for people with lower fitness levels, and to reduce fitness-related degradation and increase their physical activity. Going further, Leung and her colleague were also being funded to develop and promote sitting light volleyball among adults with physical disabilities.
Sitting volleyball is a commonly known Paralympic Sport modified from traditional volleyball to suit athletes who are disabled physically (20, 21). Despite sitting volleyball allowing players to be at a seated position in which the pelvis must contact the ground during the game, the volleyball used is seen to be unpredictable (20) and even faster than that of Olympic traditional volleyball (The British Paralympic Association, 2014), in which players with lower fitness level and sport competence are less able to access. Hence, the combination of sitting volleyball and light volleyball may be considered as an appropriate physical activity for people with physical disabilities (PWPD) as a leisure activity.
In 2018, the current research investigator (Leung KM) and her colleague (Chung PK), successfully obtained a Knowledge Transfer Partnership Seed Fund to (1) develop a new sport, sitting light volleyball (SLVB); (2) investigate the impact of a sitting light volleyball intervention on improving health among PWPD, and (3) promote SLVB by organizing SLVB classes. We pilot tested SLVB with PWPD and examined its game characteristics, rules, and regulations. SLVB was then developed using sitting volleyball from the Paralympic games as a reference. Additionally, four focus group interviews were conducted to investigate PWPD’s experiences and opinions related to SLVB. Generally, these interviews demonstrated a positive perception of playing SLVB among PWPD in HK (22). Using structural equation modelling, three themes emerged when playing SLVB at individual, and interpersonal levels. These themes included “increased perceived competence in PA”, “increased PA enjoyment”, and “increased social support and communication”. Next, the SLVB intervention resulted in significant improvements in cardiovascular endurance, body composition, PA enjoyment, and quality of life among participants in the SLVB group compared to the control group (Leung et al., 2019, unpublished work).
Hence, in correspondence with the needs of the students with physical disabilities stated by the government consultancy study and the positive findings of our pilot study in adults with physical disabilities, sitting light volleyball was then applied and the first place to study its health impact was on students in special education schools in Hong Kong.
2. Objectives
The aim of the research was to examine the effect of the sitting light volleyball intervention in improving physical fitness among students with physical disabilities. Since no research has been done on applying sitting light volleyball on students with physical disabilities, the null hypothesis expects that the sitting light volleyball intervention can generate no significant effect on the physical fitness of students with physical disabilities, neither body composition nor musculoskeletal functioning.
3. Methods
The present pilot study was a single group quasi-experimental intervention study, taken place in two (out of seven) special education schools for students with physical disability in Hong Kong.
3.1. Participants
There were only a total of seven special education schools for children with physical disabilities in Hong Kong, and due to the tight teaching schedules of students in these schools; the convenient sampling method was adopted. Eventually, only two of the schools accepted the invitation and agreed to participate in our study. The inclusion criteria of participants included: (a) school students in Hong Kong special schools serving PWPDs; (b) registered PWD in Central Registry for Rehabilitation; (c) with at least one functional arm; and (d) cognitively understand the intervention program instruction. Students who (a) had a history of cardiovascular disease that hinders study participation; (b) had seeing and hearing difficulties; and (c) were not approved by his/her physician to participate in the study due to a limiting medical condition, were excluded from the study.
In this research, 19 students, including 8 males and 11 females with the age of 18.5 on average (SD = 3.24), participated in the study. Eighteen of them were in the pre-test and the intervention, while 7 of them did not get involved in the post-test, yet 1 of them was absent from the pre-test but still involved in the intervention programme as well as the post-test. The disability conditions of the subjects were mainly loss or deformity of limbs and muscular dystrophy; from which five of them were wheelchair users.
3.2. Design and Measures
3.2.1. Procedures and Sitting Light Volleyball Intervention
The subjects were expected to be involved in the fitness test held before and after the intervention program, and they were briefed on the fitness test procedures before each test. The consent form was given to their parents in advance for endorsement. The parents were told about the process of intervention and the purpose of the current study, as well as the confidentiality of the data collected. The parents and students were also reminded that they would be allowed to withdraw from the research at any time without any penalty and without loss of benefits.
The intervention programme was carried out from November 2018 to January 2019 by two qualified registered coaches and one assistant coach from the Light Volleyball Association of Hong Kong. The program consisted of 10 sessions, with 1 session per week and 65 minutes per session. Each session involved a warm-up, sitting light volleyball skills training (supplementary file Appendix 1), and match play then finished with cool-down and stretching (23). The duration of the intervention was planned to in line with the recommended guidelines of U.S. Department of Health and Human Services Centers for Medicare and Medicaid Services (2003) of 2 sessions per week and 90 minutes per session (24); however, in considering the physical status of disabled students as well as the fixed time period of the schools’ physical education lesson, the intervention frequency and duration were being restricted. The intervention program was designed by the second author, a physical education specialist who first developed and promoted light volleyball and sitting light volleyball in Hong Kong, and she is a former player in the Hong Kong National Volleyball Team as well.
3.2.2. Fitness Test Measurement
The Brockport physical fitness test (BPFT) was used to measure the participant’s fitness level in this study. It is a criterion-referenced test of fitness, which the included items and the respected standards that were established through research findings, norms-referenced data and expert opinions were used to see whether the values were seen to be significant for the individual’s health. Another reason for utilizing this measurement is that the test manual consists of a key element of providing physical fitness test standards especially for youngsters with disabilities of age 10 or above (25). The fitness tests used in this study included: body mass index (including weight and height), skinfold test (body composition), handgrip test, dumbbell press (5 pounds, muscular endurance) and shoulder scratch (flexibility) test.
3.2.3. Body Composition
Participants’ body composition were examined by the body mass index (BMI) by using the body composition analyzer - TANITA (model MC 780 MA). By using the TANITA, the analyzer provided assessment results other than weight and BMI, such as predicted muscle mass (PMM), fat mass (FM), as well as skeletal muscle index (SMI). SMI is the ratio of the muscles in the arms and legs to the height (26). The skeletal muscle index (SMI) is also considered as worth reporting within the physical disability students’ population. The skeletal muscle index is able to identify possible loss in muscle mass. This condition can also be called as sarcopenia, and the ideal SMI is ranged from 5.67 to 7.23. Actually, this condition is usually reflected on the ageing population, however concerning the participants of the current study is students with physical disabilities that, functional impairment and physical disability tended to show a significant association with low skeletal muscle mass (27, 28). Nevertheless, it is worth noting that some of the participants were using wheelchairs so they were not able to stand on the TANITA, body composition analyses reports were not possible to generate, thus leading to the missing values in weight and BMI. But still, their height was measured by soft tape with participants at a lied down position on an exercise mat. By the same token, the skinfold test (triceps) was applied to all participants for measuring the level of estimated body fat, using the skinfold caliper (25).
3.2.4. Musculoskeletal Functioning
Musculoskeletal functioning in this study included muscle strength and muscle endurance (29). First, the handgrip test was used to measure the maximum muscle strength (in kg) of individuals. The subjects were told to grip the handle of the dynamometer and squeeze it with maximum strength. Participants performed two tries for both hands and rest time was given in between them (20, 25). Secondly, the dumbbell press was conducted to examine the strength and endurance of one’s arms and shoulders. Participants were asked to sit still, either in a wheelchair or a stable chair, and to lift a 5-pound dumbbell as many times as possible. The whole process was served by a physical education student helper for safety considerations (25). Both hands were measured with only one attempt.
3.2.5. Flexibility
Finally, a shoulder stretch test was used to assess the upper-body flexibility of the participants. The test was to measure the distance (cm) in between the fingertips of two hands placed behind the back, with one arm reached over the shoulder and with another one down the back. The test measured both hands entitled “right” or “left” on the basis of the arm reaching over the shoulder (25).
3.3. Limitations
A limitation we would have to point out is that, all students who participated were recommended and approved by the school teacher and the occupational therapist of the school. Therefore, this operation may reduce the reliability and validity of the research due to the non-randomized sample. Despite that, researchers think that it is acceptable as it would be considered as more ethical for students with physical disabilities and to avoid possible risks of activity injuries.
3.4. Statistical Analysis Method
The IBM SPSS Statistics 25 was used to carry out all statistical analysis. The current study was an experimental intervention research, a more conservative approach, intention to treat (ITT) analysis was adopted so that the data were analyzed according to the preliminary arrangement, regardless of what the subject actually received or other comorbidities that the subjects have engaged in. Also, the last observation carried forward (LOCF) method (29), was used to manage the missing data. Descriptive statistics were also used to indicate the demographic information and the body composition results of the participants. While, due to the small sample size, the nonparametric Wilcoxon signed rank test was used to analyse the one-group pretest-posttest differences.
4. Results
4.1. Descriptive Statistics
A total of 18 subjects were included in the statistical analysis, excluded one subject who did not complete the pre-test. Among the 18 subjects, (5 from school A and 13 from school B), there were 8 males and 10 females, with over half of them aged between 16 - 20 and the average age at 18.6 years old (Table 1). Overviewing the body composition status of all the subjects, the participants were equipped with healthy body composition (i.e., BMI ranged between the fifth and 85th percentile (30), with the average BMI at 20.43 (SD = 3.77), which is considered as within the healthy weight range (31). Additionally, the SMI of the participants were all above the desirable range, with mean at around 6.9 (Table 2).
Table 1.Descriptive Statistics
| Valuesa | |
|---|---|
| Gender | |
| Male | 8 (44.4) |
| Female | 10 (55.6) |
| Total | 18 (100.0) |
| Age | |
| 10 - 15 | 2 (11.1) |
| 16 - 20 | 10 (55.6) |
| 20 - 25 | 4 (22.2) |
| Total | 18.56 ± 3.24 |
aValues are expressed as No. (%) or mean ± SD.
Table 2.Descriptive Statistics for Body Composition (N = 13)
| Aspects | Mean ± SD |
|---|---|
| Weight | |
| Pretest | 48.71 ± 10.99 |
| Posttest | 49.12 ± 11.02 |
| BMI | |
| Pretest | 20.43 ± 3.77 |
| Posttest | 20.63 ± 3.72 |
| FM | |
| Pretest | 11.78 ± 6.83 |
| Posttest | 12.71 ± 6.23 |
| PMM | |
| Pretest | 35.02 ± 8.39 |
| Posttest | 34.53 ± 7.19 |
| SMI | |
| Pretest | 6.89 ± 0.90 |
| Posttest | 6.98 ± 0.99 |
4.2. Body Composition
Regarding the pretest-posttest differences on aspects of body composition, the Wilcoxon signed rank test did not reveal any significant results on all related aspects, including BMI, skinfold test (triceps), fat mass (FM) and predicted muscle mass (PMM). But still, the descriptive statistics showed a slight increase in the overall mean of the BMI, FM and SMI (27, 28). Therefore, whether a longer intervention program is able to reveal a positive body composition change among students with physical disability is still considered as uncertain (Table 2).
4.3. Musculoskeletal Functioning and Flexibility
Apart from the descriptive means demonstrate in Table 3, the pre-test and post-test differences on the handgrip test, dumbbell press and shoulder stretch test were shown by the statistical results generated from the nonparametric Paired t-test, Wilcoxon signed rank test. The results showed that the median of the post-test of both dumbbell press test (dominant and non-dominant hands) was significantly higher than that in pre-test, with Z = 2.94, P = 0.003; Z = 2.82, P = 0.005. While, the flexibility of the right hand also showed a significant median improvement on the post-test, with Z = 2.20, P = 0.028. The Wilcoxon signed rank test thus demonstrated that the subjects have shown significant improvements in muscle endurance as well as flexibility.
Table 3.Descriptive statistics for musculoskeletal functioning and flexibility
| Aspects | Mean ± SD |
|---|---|
| Handgrip-D | |
| Pretest | 15.51 ± 11.08 |
| Posttest | 15.23 ± 10.19 |
| Dumbbell press-D | |
| Pretest | 16.94 ± 13.51 |
| Posttest | 35.06 ± 18.23 |
| Flexibility-D | |
| Pretest | -12.18 ± 21.88 |
| Posttest | -15.93 ± 20.38 |
| Handgrip-nonD | |
| Pretest | 14.51 ± 11.03 |
| Posttest | 14.63 ± 9.81 |
| Dumbbell press-nonD | |
| Pretest | 15.39 ± 16.15 |
| Posttest | 33.11 ± 18.31 |
| Flexibility-nonD | |
| Pretest | -10.43 ± 21.10 |
| Posttest | -15.92 ± 20.38 |
Abbreviations: D, dominant hand; nonD, non-dominant hand; SD, standard deviation.
5. Discussion
To conclude, the current 10-week sitting light volleyball intervention program applied on students with physical disabilities, is aimed at examining its effect in improving their physical fitness based on the Brockport physical fitness test (BPFT) measurement. The intervention program showed no significant effect on the aspects of body composition but did show significant improvement in muscle endurance (using dumbbell press test) and flexibility (using shoulder stretch test).
First, it is acceptable that there were less likelihood to have a significant differences on that of BMI and muscle mass (body composition), as it was seen as difficult to have a notable change after a short duration of intervention (i.e., 10-week); in addition, the intervention has only consisted of one session per week (32). Simultaneously, the energy demand of playing volleyball is being categorized as aerobic, in which it requires the usage of large muscle groups and maintained continuously for at least 20 minutes (33). We, therefore, expected the changes in body composition may become significant when we extend the intervention duration and dosage in the future. More than that, there were still inconsistent outcomes in the literature regarding whether aerobic exercise or resistance training is more effective in reducing and maintaining body weight (34). Research indicated that aerobic-only exercise group and aerobic-resistance exercise group significantly reduce obese adults’ body weight and fat mass, but not in the resistance-only exercise group. In contrast, exercise groups with resistance exercises showed a greater change in lean body mass compared to aerobic exercise (35). Other than the type of exercises, weight compensation for aerobic exercise training is also another possible factor affecting the effectiveness of weight loss. The research highlighted that it was possible to achieve significant weight loss with high volume aerobic exercise training under caloric restriction (36). It is because participants would easily increase their energy and fat intake (37) after aerobic exercise training; while it has been concluded that dietary compensation and low aerobic exercise dose have limited the expected weight loss from aerobic exercise training.
Research has also revealed that aerobic endurance training tended to have a larger percentage of improvement on upper-body muscle endurance compared with that of muscle strength (38). In line with the context of the intervention program, participants were mainly engaged in a continuous practice with less high-intensity anaerobic acts; therefore, it can explain the outcomes that the subjects have demonstrated significant differences in muscles endurance rather than in muscle strength.
On the other hand, the program participants only showed significant differences in the flexibility of the right hand. It can be interpreted that the majority of the subjects’ dominant hands are right hand, in which they tended to use their right hand to hit the ball while the left hand was used to maintain their body balance; therefore, with a higher frequency of reaching out their dominant hand, the flexibility of the right hand tends to be improved. Moreover, concerning that a cool-down session was included after each lesson, that stretching was shown to be effective in improving the flexibility of volleyball players (39). In addition to that, most of the physical performance-related research only showed the improvement of disabled elderlies’ flexibility in stretching and balancing exercises, like yoga and vibration exercise, as well as in resistance training (40-42). Despite having mentioned that both elderly and physically disabled have a relatively weak skeletal muscle mass compared to others, in which may have similar physical movement limitations (27, 28), the current research discovered that aerobic exercises could improve the flexibility of physical disabilities.
Furthermore, in an informal survey conducted during the data collection, most of the participants also expressed their enjoyment and positive feelings towards being physically active and did think that engaging in physical activity enables them to reduce stress or negative emotions. Hence, other than measuring the change in physical fitness objectively, an extensive intervention program with follow-up testing can be done to measure the effect of SLVB in motivating physical disability students to be more physically active, then to increase their physical activity level as well as their psychological health. In fact, children with non-motor disabilities in Hong Kong, like intellectual disability and visual impairment, were given more opportunities to engage in sports activity compared with those with physical (or called as motor) disabilities. Yet, this is due to the facilities available within schools, the accessibility towards public venues from schools, manpower as well as the type of disability of the students, would hinder physically disabled students in engaging in organized physical activities. Therefore, with the statistical support for the effect of SLVB, it will be worthwhile to have SLVB to be promoted to all the special education schools in Hong Kong.
5.1. Limitations
Whereas, the small sample size, with only two special education schools involved, has increased the difficulty of the study to determine the significant effectiveness of sitting light volleyball in improving the physical fitness of students with physical disabilities. Also, being a quasi-experimental research, without a control group, is also a concern that made the interventional effects less comparable; as well as reduced the prominent aspects of the intervention. Besides, the duration and sessions of the program are other concerning issues. It is essential to consider that the physical condition of students in the special education school might quite vary and that a longer duration or more sessions may lead to serious fatigue for students with a poorer physical condition. Additionally, it is noteworthy that some of the subjects within the current study are athletes with disabilities or even para-athletes. Hence, their professional athlete training was considered as a confounding variable of the intervention effect; and yet, it is also a limitation of having the intended-to-treat approach. However, significant pretest-posttest differences in two of the physical fitness test items could still conclude that this pilot intervention study does provide preliminary evidence that sitting light volleyball has a potential effect on enhancing the physical fitness of students with physical disabilities, thus the intervention scale should be enlarged for future implication.
