This cross-sectional exploratory study aimed to compare the one-leg-stance time and the six-minute walk distance among TC Qigong-trained NPC survivors, untrained NPC survivors, and healthy individuals. Twenty-five survivors of NPC with TC Qigong experience, 27 survivors of NPC without TC Qigong experience, and 68 healthy individuals formed the NPC-TC Qigong group, NPC-control group, and healthy-control group, respectively. The one-leg-stance (OLS) timed test was conducted to assess the single-leg standing balance performance of the participants in four conditions: (1) standing on a stable surface with eyes open, (2) standing on a compliant surface with eyes open, (3) standing on a stable surface with eyes closed, and (4) standing on a compliant surface with eyes closed. The six-minute walk test (6MWT) was used to determine the functional balance performance of the participants. Results showed that the NPC-control group had a shorter OLS time in all of the visual and supporting surface conditions than the healthy control group
Nasopharyngeal cancer (NPC) is a rare malignancy in North America and Europe (incidence rate: 1 per 100,000) but is common in endemic areas that include the southern part of China, Southeast Asia, and North Africa. The incidence rate ranges from 25 to 50 per 100,000 in these endemic regions [
Tai Chi (TC) Qigong, which integrates the essence of TC and Qigong, is a Chinese physiotherapeutic approach that consists of breathing exercises coordinated with slow body movements and balance training in an upright posture. It is a type of mind-body exercise and is particularly suitable for patient populations because it is relatively simpler and more repetitive than the traditional TC forms [
This is a cross-sectional study. One hundred and twenty senior adults participated in the study voluntarily. Survivors of NPC with TC Qigong experience
Sixty-eight healthy senior adults were recruited from two local community centers. They followed the same inclusion and exclusion criteria mentioned above except that they did not have any history of NPC and TC Qigong experience. Written informed consent was obtained from each participant before the data collection. All of the procedures were conducted according to the Declaration of Helsinki, and all of the experimental work was carried out with the approval of the ethics review committee of the administering institution.
Demographic characteristics and medical history were first obtained by interviewing the participants (Table
Characteristics of the participants.
NPC-TC Qigong group |
NPC-control group |
Healthy-control group |
| |
---|---|---|---|---|
Age (year) |
|
|
|
0.331 |
Sex (male : female) | 12 : 13 | 16 : 11 | 50 : 18 | 0.057 |
Weight (kg) |
|
|
|
|
Height (cm) |
|
|
|
0.124 |
Body mass index (kg/m2) |
|
|
|
<0.001 |
Reported NPC stage at diagnosis [ | ||||
Stage I ( |
5 (20%) | 2 (7.4%) | — | |
Stage II ( |
5 (20%) | 7 (25.9%) | — | |
Stage III ( |
11 (44%) | 15 (55.6%) | — | |
Stage IV ( |
4 (16%) | 3 (11.1%) | — | |
Post-NPC duration (year) |
|
|
— | 0.094 |
NPC treatment received | ||||
Radiotherapy ( |
17 (68%) | 9 (33.3%) | — | |
Radiotherapy and chemotherapy ( |
7 (28%) | 18 (66.6%) | — | |
Radiotherapy, chemotherapy, and surgery ( |
1 (4%) | 0 (0%) | — |
The mean ± standard deviation is presented for the continuous variables.
The one-leg-stance timed test was conducted to assess standing balance. The participants were instructed to stand barefoot on their dominant leg (1) on a stable surface (ground) with eyes open; (2) on a compliant surface (Stability Trainer, The Hygienic Corporation, Ohio, USA) with eyes open; (3) on a stable surface (ground) with eyes closed; and (4) on a compliant surface (Stability Trainer) with eyes closed. Their arms were at rest on either side of the trunk. In the two eyes-open trials, the participants were instructed to focus on a spot on a nearby wall in front of them. Close guarding was provided to prevent falls during the trials. A stopwatch was used to record the duration of standing (in seconds). The OLS time commenced when the nondominant foot left the ground and ended if the same foot touched the ground or rested against the other leg or the participants hopped on the weight-bearing leg or shifted on the weight-bearing foot or opened their eyes in the eyes-closed trials or when a 60-second OLS duration was reached [
The six-minute walk test (6MWT) was used to determine the functional balance performance of the participants [
The Statistical Package for the Social Sciences (SPSS) version 20.0 software was used to perform the statistical analyses. All of the demographic and outcome variables were presented using descriptive statistics. The normality of the continuous data was checked using the Kolmogorov-Smirnov test. One-way analysis of variance (ANOVA) was used to compare the age, weight, height, and body mass index of the three groups. A Chi-squared test was used to compare the sex ratio of the groups. In addition, an independent
For the analyses of the balance and functional outcomes, one-way analysis of covariance (ANCOVA) was used to compare the differences among the three groups. Bonferroni tests were used to analyze the data post hoc as necessary. A significance level of 0.05 (two-tailed) was set for all of the statistical tests.
The characteristics of the three groups of participants are presented in Table
The results revealed a significant difference in OLS time among the three groups
Comparison of the balance outcomes of the three groups.
Useful sensory inputs |
NPC-TC Qigong
group |
NPC-control group |
Healthy-control group |
|
|||
---|---|---|---|---|---|---|---|
NPC-TC Qigong group versus NPC-control group | NPC-TC Qigong group versus healthy-control group | NPC-control group versus healthy-control group | |||||
One-leg-stance times | |||||||
(1) On ground with eyes open (s) | Somatosensory, visual, and vestibular |
|
|
|
1.000 |
|
|
(2) On stability trainer with eyes open (s) | Visual and vestibular |
|
|
|
1.000 |
|
|
(3) On ground with eyes closed (s) | Somatosensory and vestibular |
|
|
|
1.000 |
|
|
(4) On stability Trainer with eyes closed (s) | Vestibular |
|
|
|
1.000 |
|
|
Six-minute walk distance (m) | — |
|
|
|
0.528 | 1.000 | 0.629 |
The mean ± standard deviation is presented for all of the variables.
An overall significant difference among the three groups was found
The ANCOVA result was significant
The ANCOVA result was also significant
There was no significant difference among the three groups in the distance covered in the 6MWT
This is the first study to show that participating survivors of NPC had inferior OLS balance performances in all of the visual and supporting surface conditions compared with age-matched healthy counterparts. Given that postural control requires the ability to utilize sensory inputs (i.e., somatosensory, visual, and vestibular inputs) and to generate coordinated motor outputs [
With TC Qigong training, the participating survivors of NPC had a similar OLS balance performance in condition 3 (i.e., stood on a stable surface with eyes closed) to that of the healthy individuals, although they were still no better than the NPC controls. As somatosensory input is the dominant sensory input for balance under a stable support surface and eyes closed condition [
Ample evidence supports that TC and Qigong training can improve the use of vestibular input to balance [
When relying primarily on visual input to balance (i.e., condition 2—stood on a compliant surface with eyes open), the healthy control group also outperformed the two NPC groups, while the two NPC groups performed similarly. This suggests that TC Qigong training might not be able to improve the use of visual input for postural control in survivors of NPC, perhaps because the vestibuloocular reflex is also disrupted in survivors of NPC who undergo radiotherapy [
Interestingly, we found that when the three sensory inputs were present and accurate (condition 1), both the NPC-TC Qigong and the NPC control groups had a shorter OLS duration than the healthy control group. In addition, both groups of NPC survivors balanced similarly in the OLS. The TC Qigong-trained NPC survivors might have been unable to match the healthy controls in terms of OLS performance because, typically, dysfunction in any one of the three senses that contribute to balance can be compensated by inputs from the other two sensory systems. For example, dysfunction of the vestibular system may be compensated by enhancing somatosensory awareness and visual attention to better balance [
The sensorimotor deficits of postural control among the survivors of NPC, both with and without TC Qigong training, were not reflected in the six-minute walk test result. This result might be because this test is too general as it assesses both the balance ability and the functional aerobic capacity of the participants [
Some limitations to this study warrant comment. First, the use of a convenience sample may have introduced a self-selection bias that may threaten the internal validity of the study. In addition, our rather homogenous subject group may limit the generalizability of results [
Irradiated survivors of NPC had inferior single-leg standing balance performance relatively to the healthy individuals. The survivors of NPC who were trained in TC Qigong might have relied more on their somatosensory input to maintain single-leg standing balance. Their one-leg-stance time on a stable surface with eyes closed was comparable to that of healthy individuals. However, survivors of NPC, both with and without TC Qigong training, had a shorter OLS time than healthy controls when they stood (1) on a stable surface with eyes open, (2) on a compliant surface with eyes open, and (3) on a compliant surface with eyes closed. The six-minute walk distance was comparable among NPC survivors with and without TC Qigong training and healthy controls. Our results hint that TC Qigong might be a potential rehabilitation exercise to improve the somatosensory function and single-leg standing balance performance of survivors of NPC.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Shirley S. M. Fong contributed to the conceptualization of the study, supervised the data collection and analysis processes, and wrote the first draft of the paper. Louisa M. Y. Chung contributed to the conceptualization of the study, was involved in the data collection and analysis process, and contributed to the write-up of the paper. William W. N. Tsang contributed to the conceptualization and revision of the paper. Joyce C. Y. Leung contributed to the conceptualization of the study, was involved in the data collection and analysis process, and contributed to the write-up of the paper. Caroline Y. C. Charm contributed to the conceptualization of the study, cosupervised the data collection process, and contributed to the write-up of the paper. W. S. Luk contributed to the conceptualization of the study, assisted in the recruitment of participants, cosupervised the data collection process, and contributed to the write-up of the paper. Lina P. Y. Chow contributed to the conceptualization of the study, was involved in the data collection process, and contributed to the write-up of the paper. Shamay S. M. Ng contributed to the conceptualization of the study, cosupervised the data collection and analysis processes, and contributed to the write-up of the paper.
This study was supported by a Seed Fund for Basic Research for New Staff (201308159012) from the University of Hong Kong and an Internal Research Grant (RG57/2012-2013R) from the Hong Kong Institute of Education.