Assessment of Asymmetrical Lower Limb Range of Motion in Six-Step, a Basic Footwork in Breakdance (Breaking)

Updated on:
October 16, 2026
Rob Kanko
Rob Kanko is a biomechanist and Head of Support at Theia, bringing an extensive biomechanics research background and a passion for distance running to his work. He has published multiple studies on Theia3D and supports customers and internal teams across a range of biomechanics research and software applications.
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Summary

With the inclusion of breaking as an official Olympic sport at Paris 2024, the acrobatic dance genre has garnered attention from the public, media, and researchers alike. Recent research has found a higher incidence of musculoskeletal injuries among breakers, particularly in the lower limbs. A team at Ehime University in Japan used markerless motion capture to study Six-Step, the most fundamental footwork pattern in breaking and one performed by dancers at every skill level, to find out exactly how much range of motion (ROM) is required of each leg in this inherently asymmetric movement.

Disclaimer: The following summary details independent academic research. Theia3D is intended for research, sports performance and educational use only. It is not cleared as a medical device and is not intended to be used for the diagnosis, treatment, mitigation or prevention of any disease, injury or medical condition.

Editor’s note: This study used Theia3D version 2021.2.0.1675.

Why This Matters

Six-Step involves one full rotation of the lower body across six phases, executed either clockwise or counterclockwise depending on which side the dancer uses as their stabilizing axis. Because the movement is inherently asymmetric, the authors suspected that joint demands on the axis leg and the non-axis leg would differ meaningfully, and movement asymmetry is already an established injury risk factor in dance generally. Despite breaking’s injury rates and its new Olympic status, the detailed joint kinematics of its most basic move hadn’t been documented. This study set out to fill that gap and give the field a quantitative baseline for a skill every breaker performs.

Study Overview

Design

A cross-sectional study using markerless motion capture to measure hip and knee ROM on both the axis and non-axis side during the Six-Step sequence.

Participants

10 experienced breakdancers (9 male, 1 female; mean age 29.0, range 8 to 39), all with substantial competitive or instructional experience in breaking. The paper’s own equity and inclusion statement notes that the sample was predominantly male and exclusively Asian, and that findings may not generalize to novice breakers or more demographically varied groups.

Procedure

Each participant performed four continuous Six-Step cycles, from which the second and third cycles were selected for analysis to minimize acceleration effects. Six synchronized video cameras recorded the movements at 85 Hz and 1080p resolution, and hip and knee joint angles were measured across all three planes of motion on both the axis and non-axis side.

Data Quality Control

Before proceeding with the analysis, researchers examined the within-subject repeatability of the knee and hip ROM, and the individual movement directions (e.g. flexion, extension, etc.) to determine the reproducibility of these measures. Only those measures that showed statistically significant differences and achieved an ICC > 0.7 were considered acceptably reproducible for this study, and included in the analysis. Knee extension and hip flexion fell below that threshold and were excluded.

Key Findings

The axis-side leg carried significantly greater demand at both the hip and the knee. Axis-side hip adduction averaged 20.3 degrees compared to 9.2 degrees on the non-axis side, and axis-side knee flexion averaged 152.8 degrees compared to 142.0 degrees on the non-axis side. Both differences were statistically significant.

Axis-side knee flexion approached the physiological maximum seen in healthy individuals. The authors connect this to prior research showing that deep knee flexion under load generates substantial quadriceps force, cartilage contact stress, and meniscus pressure, and note that the knee is already the most frequently injured lower-limb site reported in breaking.

On the axis side, hip and knee motion moved together rather than compensating for each other. Knee flexion ROM on the axis side was strongly correlated with axis-side hip adduction and, even more strongly with axis-side hip internal rotation. The authors contrast this with ballet, where limited hip mobility is typically compensated for by greater knee motion, a relationship with an opposite pattern from what they found in Six-Step.

Axis-side hip adduction exceeded the range typically needed for everyday activities. The authors link this to case reports of unilateral pelvic avulsion fractures at the adductor attachment site in breakers, suggesting the Six-Step’s adduction demand may be a specific contributor to that injury pattern.

None of the measured participant characteristics explained the asymmetry. Age, height, weight, BMI, years of practice, grip strength differences, and limb length were all tested, and none were correlated with the interlimb difference in maximum ROM . The authors interpret this as evidence the asymmetry is built into the movement itself rather than something that varies by dancer experience or body type.

What This Means for Dance Performance Research

This study gives dance medicine practitioners and coaches a concrete, joint-level biomechanical description of one of breaking’s most foundational movements, broken down by axis/non-axis side. In doing so, this study confirms the inherent asymmetry of the Six-Step movement, regardless of the dancer’s experience level or physical characteristics,reframing the question from “how do we reduce this asymmetry” to “how do we prepare dancers to safely handle the expected asymmetry.” This has direct implications for strength and mobility work in breaking-specific training.

The Role of Theia3D in Movement Analysis

Breaking’s acrobatic, floor-based movement makes it a genuinely difficult subject for traditional marker-based capture, between the rapid transitions, hand-to-floor contact, clothing that shifts constantly during the routine, and inter-limb contacts that would result in markers being dropped. Markerless motion capture lets the researchers record Six-Step in a natural performance setting, with participants in their usual training attire, without markers interfering with the movement itself. The team also built a reliability check directly into their methodology, confirming which joint-angle measurements repeated consistently between cycles before drawing any conclusions from them, which is a meaningful methodological safeguard for a sport this dynamic.

Study Limitations and Future Directions

The sample was small, 10 participants, though the authors ran a power analysis beforehand to support that size for the study’s primary comparison. A post-hoc check on the correlation analyses found the study was likely underpowered for weak-to-moderate relationships, so the absence of a correlation between ROM asymmetry and participant characteristics shouldn’t be read as proof no such relationship exists. Movement speed wasn’t standardized across participants, though the authors note variability was minimal and prioritized each breaker’s natural performance speed. The study also didn’t test whether this asymmetry is actually harmful to injury risk or performance, only that it exists and is consistent. The authors are explicit that their sample skewed heavily male and was exclusively Asian, and call for broader, more demographically varied recruitment in future work. Finally, the study utilized a relatively old version of Theia3D (2021.2.0.1675) and thus the results may differ slightly from those produced using up-to-date software with a higher number of tracked keypoints and improved tracking algorithms.

Full Study and Further Reading

Citation: Tsuda, T., Kutsuna, T., Kiyomatsu, H., Kinoshita, T., & Takao, M. (2026). Assessment of asymmetrical lower limb range of motion in Six-Step, a basic footwork in breakdance (breaking). Journal of Dance Medicine & Science. Advance online publication.

Link: Read the full study

Studying Movement Demands in Dance or Performing Arts?

This study shows markerless capture working in one of the more physically demanding, floor-based movement contexts in sport, without markers getting in the way of the performance itself. If you’re researching injury risk or movement demands in dance, gymnastics, or other acrobatic disciplines, talk to our team about what a study like this could look like for your population.

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