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Morio Y1,2,3, Omori Y1, Sakurai Y1, Nagasawa H1, Nakao Y1, Saito K1, Koyama S3, Sakanoue N1
1Shonan University of Medical Sciences, Faculty of Medical Sciences, Yokohama, Japan, 2University of Tsukuba, Graduate School of Comprehensive Human Sciences, Tokyo, Japan, 3St. Marianna University School of Medicine, Department of Rehabilitation, Kawasaki, Japan
Background: The “Two Square Step Test” requires subjects to step over an obstacle. It is easily performed using a bar, and can also be used as a training exercise for the purpose of improving balance or performance. However, the exercise intensity of variation in stepping pace and obstacle height has not been fully elucidated.
Purpose: The objective of this study was to investigate changes in toe clearance (TC) as a result of changes in rhythmic auditory cueing (RAC) and obstacle height, with the aim of identifying the appropriate RAC and obstacle height for physical therapy.
Methods: The study subjects were 11 healthy young adult men. The RAC was defined by asking the subject to complete a 30-m course at their own speed, calculating the cadence (steps/min), which was considered as 100% RAC. A total of 15 bar-stepping tasks, comprising combinations of RAC at five speeds (80%, 100%, 120%, 140%, and 160% of the mean cadence) and three obstacle heights (0, 2.5, and 10 cm), were randomly assigned to the subjects. The bar-stepping task was repeated 15 times with RAC provided by a metronome. The outcomes were the TC of the lead and trailing legs when stepping over the obstacle, which were measured using a three-dimensional motion analyzer (MX-T20S, Vicon Motion Systems Limited). Heart rate during the task was measured as another outcome. One-way analysis of variance was used for statistical analysis, which was carried out using SPSS (Version 25.0).
Results: In all the RAC tests, TC was lower in the trailing leg than in the lead leg. TC was greater for obstacle heights of 2.5 cm and 10 cm than for 0 cm. The participants stumble in 8% of test when the obstacle height was 10 cm, but there was no participants who stumble the obstacle height of 2.5 cm. Heart rate reserve (k) exceeded 0.6 in 73% of the tests with an obstacle size of 10 cm and RAC of 160%.
Conclusion(s): We found that TC was lower in the trailing leg, suggesting that this leg causes stumbling. TC can be increased by increasing the obstacle height from 0 cm to 2.5 or 10 cm; however, training with an obstacle height of 10 cm entails the risk of falls. At an obstacle height of 10 cm and RAC of 160%, the aerobic metabolism threshold may be exceeded, suggesting overexertion. From the perspective of effective TC and safety, the optimal intensity of bar-stepping exercises may be with an obstacle height of 2.5 cm and RAC of either 120% or 140%.
Implications: In this study, the optimal intensity of bar-stepping exercises was found to be with an obstacle height of 2.5 cm and RAC of either 120% or 140%. In the future, we would like to apply it in elderly population and verify the effect on improvement in exercise capacity. If we can demonstrate an improvement, there is a possibility of quantitative training that can be easily provided, without any complex machinery.
Keywords: Rhythmic auditory cueing, Exercise intensity, Toe clearance
Funding acknowledgements: This work was supported by JSPS KAKENHI Grant Number JP18K10555, JSPT Grant Number H29-A29.
Purpose: The objective of this study was to investigate changes in toe clearance (TC) as a result of changes in rhythmic auditory cueing (RAC) and obstacle height, with the aim of identifying the appropriate RAC and obstacle height for physical therapy.
Methods: The study subjects were 11 healthy young adult men. The RAC was defined by asking the subject to complete a 30-m course at their own speed, calculating the cadence (steps/min), which was considered as 100% RAC. A total of 15 bar-stepping tasks, comprising combinations of RAC at five speeds (80%, 100%, 120%, 140%, and 160% of the mean cadence) and three obstacle heights (0, 2.5, and 10 cm), were randomly assigned to the subjects. The bar-stepping task was repeated 15 times with RAC provided by a metronome. The outcomes were the TC of the lead and trailing legs when stepping over the obstacle, which were measured using a three-dimensional motion analyzer (MX-T20S, Vicon Motion Systems Limited). Heart rate during the task was measured as another outcome. One-way analysis of variance was used for statistical analysis, which was carried out using SPSS (Version 25.0).
Results: In all the RAC tests, TC was lower in the trailing leg than in the lead leg. TC was greater for obstacle heights of 2.5 cm and 10 cm than for 0 cm. The participants stumble in 8% of test when the obstacle height was 10 cm, but there was no participants who stumble the obstacle height of 2.5 cm. Heart rate reserve (k) exceeded 0.6 in 73% of the tests with an obstacle size of 10 cm and RAC of 160%.
Conclusion(s): We found that TC was lower in the trailing leg, suggesting that this leg causes stumbling. TC can be increased by increasing the obstacle height from 0 cm to 2.5 or 10 cm; however, training with an obstacle height of 10 cm entails the risk of falls. At an obstacle height of 10 cm and RAC of 160%, the aerobic metabolism threshold may be exceeded, suggesting overexertion. From the perspective of effective TC and safety, the optimal intensity of bar-stepping exercises may be with an obstacle height of 2.5 cm and RAC of either 120% or 140%.
Implications: In this study, the optimal intensity of bar-stepping exercises was found to be with an obstacle height of 2.5 cm and RAC of either 120% or 140%. In the future, we would like to apply it in elderly population and verify the effect on improvement in exercise capacity. If we can demonstrate an improvement, there is a possibility of quantitative training that can be easily provided, without any complex machinery.
Keywords: Rhythmic auditory cueing, Exercise intensity, Toe clearance
Funding acknowledgements: This work was supported by JSPS KAKENHI Grant Number JP18K10555, JSPT Grant Number H29-A29.
Topic: Human movement analysis; Health promotion & wellbeing/healthy ageing; Primary health care
Ethics approval required: Yes
Institution: Shonan University of Medical Sciences
Ethics committee: Institutional Committee on Human Research
Ethics number: 17-019
All authors, affiliations and abstracts have been published as submitted.
