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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Adding a 15-miute rope skipping activity to physical education class: The effect on students’ physical activity levels
Scientific title
School-based rope skipping intervention for adolescents in Hong Kong: Effect on students’ moderate-to-vigorous physical activity in physical education classes
Secondary ID [1] 283103 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Physical inactivity 289943 0
Low levels of physical activity during physical education 289944 0
Condition category
Condition code
Public Health 290317 290317 0 0
Health promotion/education

Study type
Description of intervention(s) / exposure
The intervention will be a 15-minute rope skipping activity that is implemented by the class physical education (PE) teacher at the start of four consecutive PE lessons. After the rope skipping activity, the normal lesson will be resumed. A four-lesson duration was chosen because, following Hong Kong governmental guidelines, the typical length of teaching an activity during PE is four lessons. In the first two lessons of the four-lesson intervention period, a skipping ambassador (i.e., a university student with rope skipping performance experience) will be sent to each class to assist the teacher in running the 15-minute activity and instructing students.

A 4-hour workshop will be provided to teachers of classes allocated to the experimental group. The goal of running the workshop is to teach PE teachers basic rope skipping skills, and to demonstrate how the intervention could be delivered in their class. Rope skipping ambassadors will also attend the workshop to familiarize themselves with the teachers and the structure of the 15-minute activity. The workshop will be led by a professional rope skipping coach (“the coach”), who has taught as a full-time school PE teacher.

The workshop will consist of four sections. In the first section, teachers will be taught rope skipping techniques. These techniques will be included in the two 15-minute rope skipping activities proposed to teachers. In the second section of the workshop, the coach will demonstrate the two proposed 15-minute rope skipping routines that could be implemented by teachers during their lessons in the intervention period. In this session, teachers will be asked to follow the routine led by the coach. The goal of this task is to help teachers understand how the intervention could be implemented, and to experience the intervention from a student’s perspective.

In the third section of the workshop, the coach will discuss with teachers good and poor practices when conducting the intervention, in terms of how to maximise students’ physical activity within the 15-minute period. Videos will be shown to teachers to assist in the discussion. Videos of good practices will feature the coach teaching one technique by 1) breaking down the skill into series of easier skills; 2) allowing students to adjust to different levels of difficulty; 3) helping students develop the skill by drawing on their previous rope skipping skills and experiences. These practices will encourage students even of lower abilities to remain engaged in physical activity. In contrast, the video showing poor teaching practices will feature the coach 1) spending too much time teaching verbally when students stand or sit still; 2) teaching a skill that may be too difficult for most students.

In the fourth section of the workshop, the rope skipping coach will lead discussion about potential challenges teachers may face when conducting the intervention, and ways to overcome these obstacles. Teachers will be encouraged to contribute to the discussion by drawing on their experiences at their respective schools and during the workshop. The goal of the discussion is to ensure all teachers have similar knowledge and expectations for conducting the rope skipping activity, and therefore reduce the discrepancies in the actual implementations of the activity.

Teachers in the experimental group will be asked not to discuss the content of the workshop with control group teachers whom they may encounter. To ensure intervention fidelity (experimental group) and test for any contamination effects (control group), a rater blinded to study hypotheses will observe all the PE lessons run by each teacher during the follow-up period (including experimental and control groups). The System for Observing Fitness Instruction Time (SOFIT; McKenzie et al., 1991) will be used by the rater to record the activities students engaged in during each lesson. Further to rating the activity levels of students using the protocol, raters will also record whether the student is engaging in activities related to rope skipping. Raters will be university students from a Hong Kong university. They will receive a 2-hour training session on how to use the rating protocol used in the study. Video recordings of PE lessons, for classes in both experimental and control groups, during the intervention period will be made. At least one rating made by each rater will be cross-checked by an investigator of the study using the recorded videos clips to ensure accuracies of ratings and inter-rater reliability.
Intervention code [1] 287820 0
Treatment: Other
Intervention code [2] 287821 0
Comparator / control treatment
No treatment, delayed intervention
Control group

Primary outcome [1] 290356 0
The primary outcome of the study is the proportion (in percentage) of PE lesson students spend in moderate-to-vigorous physical activity (MVPA). This will be measured using ActiGraph GT3X+ accelerometers. MVPA will be defined using Evenson and colleagues’ criteria, and 1-second epochs will be used.
Timepoint [1] 290356 0
Accelerometry measurements will be taken during four lessons at baseline (before randomisation), and taken again during the 4-lesson intervention period (after randomisation).
Secondary outcome [1] 304352 0
Proportion of PE lesson students spend in sedentary, light, moderate, and vigorous physical activity
Timepoint [1] 304352 0
Accelerometry measurements will be taken during four lessons at baseline (before randomisation), and taken again during the 4-lesson intervention period (after randomisation).
Secondary outcome [2] 304353 0
Students’ perception of autonomy support provided by their teachers during the last four PE lessons, measured using a modified Learning Climate Questionnaire
Timepoint [2] 304353 0
1 week before randomisation and 4 weeks after randomisation
Secondary outcome [3] 304354 0
Students’ motivation (autonomous motivation, controlled motivation, and amotivation) toward PE, measured using the Perceived Locus of Causality Questionnaire
Timepoint [3] 304354 0
1 week before randomisation and 4 weeks after randomisation

Key inclusion criteria
Students in selected physical education classes
Minimum age
12 Years
Maximum age
18 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
All participants will need to complete the Physical Activity Readiness Questionnaire (PAR-Q) before the study. Participants will be excluded from the study if they were deemed to be unfit for taking part in physical activity.

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Baseline measures will be dummy coded and sent to a statistician from an outside party, who will allocate classes into intervention and control groups. This statistician will not have access to the list of schools to be randomised, and therefore allocation of groups will be concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomization and allocation to intervention and control groups will be conducted after baseline measures are taken. Matched-pairs cluster randomization will be used. That is, randomization and group allocation will be conducted at the cluster (i.e., class) level. Specifically, participating classes will be matched in comparable pairs in terms of 1) class gender, 2) students’ percentage of time spent in MVPA measured at baseline, and 3) whether rope skipping is included in the school’s original PE curriculum.
Baseline measures will be dummy coded and sent to a statistician not within the research group, who will match the pairs and randomise classes into intervention and control groups.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Sample sizes were calculated based on the effect sizes calculated from Lonsdale et al.’s (2013) systematic review and meta-analysis. In their study, Lonsdale et al. found that the standardized difference, or Cohen’s d, of fitness infusion interventions implemented within PE classes to be 1.4. Adopting a conservative approach, we based our power calculation on projected effect of d = 1.0. The required sample size was calculated using GPower 3.1, with alpha level set to .05, and power at .80. The required sample size for a two-tailed independent sample t-test was found to be 34 students.

To account for the clustering nature of the data, the required sample size of 34 was adjusted by design effect of 1+(m-1)r, where m is the sample size of each cluster and r is the intraclass coefficient (ICC). In order to limit the disruption to classes to a minimum when distributing accelerometers, we decided to administer the device to 20% of students for a typical class size of 35. That is, PA levels of seven students from each class will be measured using accelerometers. Aelterman et al. (2012) found in their study that the ICC of MVPA between classes was .63. Using these estimates, the required correction factor is 1+(7-1).63 = 4.78, meaning that the total required sample size is 163 (4.78 x 34 students). Therefore, 24 classes will need to be recruited for the study (24 classes * 7 students = 168 students).

For questionnaire data, all students from these 24 classes will be recruited.

Statistical methods:
Multilevel modeling will be used to account for clustering of participants. Specifically, a two-level (student within class) model will be examined. Effects of group allocation on the outcomes and class gender will be examined using a multilevel regression model. The group x gender interaction effect will also be examined to determine whether the effect of the intervention is homogeneous across genders. Two-tailed tests with an alpha level of .05 will be used to determine the significance of all results.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 5347 0
Hong Kong
State/province [1] 5347 0

Funding & Sponsors
Funding source category [1] 287864 0
Name [1] 287864 0
The Coca-Cola Foundation
Address [1] 287864 0
The Coca-Cola Foundation
The Coca-Cola Company
P.O. Box 1734
Atlanta, GA 30301
Country [1] 287864 0
United States of America
Primary sponsor type
Department of Sports Science and Physical Education, The Chinese University of Hong Kong
Department of Sports Science and Physical Education
G05 Kwok Sports Building,
The Chinese University of Hong Kong,
Hong Kong
Secondary sponsor category [1] 286593 0
Name [1] 286593 0
Address [1] 286593 0
Country [1] 286593 0

Ethics approval
Ethics application status
Ethics committee name [1] 289808 0
Joint Chinese University of Hong Kong - New Territories East Cluster Clinical Research Ethics Committee
Ethics committee address [1] 289808 0
Joint CUHK-NTEC Clinical Research Ethics Committee
Flat 3C, Block B, Staff Quarters
Prince of Wales Hospital
Shatin, NT
Ethics committee country [1] 289808 0
Hong Kong
Date submitted for ethics approval [1] 289808 0
Approval date [1] 289808 0
Ethics approval number [1] 289808 0

Brief summary
The primary purpose of the study is to examine whether a 15-minute rope skipping activity inserted in a typical physical education lesson can increase students' physical activity within the lesson
Trial website
Trial related presentations / publications
Ha, A. S., Lonsdale, C., Ng, J. Y. Y., & Lubans, D. R. (2014). A school-based rope skipping intervention for adolescents in Hong Kong: Protocol of a matched-pair cluster randomized controlled trial. BMC Public Health, 14:535. doi:10.1186/1471-2458-14-535

Ng, J. Y. Y., Ha, A. S., Lonsdale, C., & Lubans, D. (2014, May). Clustered randomized controlled trial of a skipping intervention aimed to increase Hong Kong students’ physical activity levels during school physical education. Poster presented at the ISBNPA Conference, San Diego.
Public notes

Principal investigator
Name 42506 0
Prof Amy HA
Address 42506 0
G05 Kwok Sports Building,
The Chinese University of Hong Kong,
Shatin, NT
Country 42506 0
Hong Kong
Phone 42506 0
+852 39436083
Fax 42506 0
Email 42506 0
Contact person for public queries
Name 42507 0
Dr Johan Y Y Ng
Address 42507 0
Kwok Sports Building
The Chinese University of Hong Kong
Shatin, NT
Country 42507 0
Hong Kong
Phone 42507 0
+852 39436098
Fax 42507 0
Email 42507 0
Contact person for scientific queries
Name 42508 0
Dr Johan Y Y Ng
Address 42508 0
Kwok Sports Building
The Chinese University of Hong Kong
Shatin, NT
Country 42508 0
Hong Kong
Phone 42508 0
+852 39436098
Fax 42508 0
Email 42508 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary