RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
99
Articles
José Ignacio Popa Guerra
Universidad de Holguín, Cuba
joseignaciopopaguerra@gmail.com
ORCID https://orcid.org/0009-0002-9947-0602
Francisco Freyre Vázquez
Universidad de Holguín, Cuba
ffreyrev@uho.edu.cu
ORCID https://orcid.org/0000-0001-9553-0626
Argimiro Velázquez González
Universidad Estatal de Milagro, Ecuador
avelazquezg@unemi.edu.ec
ORCID https://orcid.org/0000-0002-7580-2556
Abstract: Introduction: The reverse roundhouse
kick Ura Mawashi Geri is a key technique in
competitive karate-do. Its power depends on
multiple biomechanical factors, but no integrative
index exists. Furthermore, horizontal efficiency
(jump relative to anthropometric measures) has
not been studied in this context. Objective: To
calculate a power index (PI) and two horizontal
efficiency indices (HEI1 = horizontal jump / leg
length; HEI2 = horizontal jump / height) in 16
male youth karateka (16-19 years) and analyze their
relationships. Methods: Cross-sectional study.
study. Horizontal jump (HJ), leg length (LL),
height, impact force (Fpeak), ankle velocity
(vankle), execution time (texec), and hip angular
velocity (ωhip) were measured. PI was calculated as
(Fpeak × vankle) / texec. Pearson correlation was
used. Results: PI showed high correlation with HJ
(r=0.82) and with both HEI (r=0.76 with HEI1;
r=0.79 with HEI2). ωhip was the main predictor of
PI (β=0.71). Mean values were PI=48270 N·m/s²,
HEI1=2.47, HEI2=1.23. Conclusions: PI is a valid
instrument. The proposed HEIs are easy to
calculate in the dojo and allow classification of
jump efficiency relative to anthropometry. Their
complementary use in performance evaluation is
recommended.
Keywords: karate; biomechanics; horizontal jump;
efficiency; power.
Indexes of power and horizontal efficiency in the kick ura mawashi geri
jodan in the karate-do
José Ignacio Popa Guerra
1
; Francisco Freyre Vázquez
2
& Argimiro Velázquez González
3
RIAF. International Journal of Physical Activity
Universidad de Guayaquil, Ecuador
Frequency: Semi-annual
Vol. 4, N°2, 2026
revista.riaf@ug.edu.ec
Received: May 30th, 2026
Approved: July 1
st
, 2026
Published: July 25
th
, 2026
URL: https://revistas.ug.edu.ec/index.php/riaf
DOI: https://doi.org/10.53591/riaf.v4i2.3339
The authors who publish in RIAF acknowledge and accept the
following conditions: Authors retain copyright of their work and grant
RIAF the right to first publication under the Creative Commons
Attribution-NonCommercial-No Derivatives 4.0 International
License, which allows third parties to share the work provided that its
author and first publication in this journal are indicated. Authors
retain copyright and guarantee RIAF the right to publish the work
through any channels deemed appropriate. Authors are free to share,
copy, distribute, perform, and publicly communicate the published
version of the work in RIAF, acknowledging its publication in this
journal. Authors are authorized to disseminate their work
electronically once accepted for publication.
This work is licensed under a Creative Commons Attribution-
NonCommercial-No Derivatives 4.0 International License.
RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
100
Introduction
Karate-do, an Olympic sport since Tokyo 2020, has demanded greater objectivity in the evaluation of
technical performance (Chaabene et al., 2015). Among the most effective and complex techniques is the
reverse roundhouse kick Ura Mawashi Geri Jodan, which requires rapid hip rotation, a whip-like leg
movement, and precise impact with the heel (Neto et al., 2021). In the male youth category (16-19 years),
the development of explosive strength reaches its peak, making it crucial to have quantitative tools for
monitoring training (Loturco et al., 2018). Traditionally, power has been evaluated through impact force
or kick velocity separately. However, these isolated measures do not reflect the neuromuscular integration
that occurs during the movement. Therefore, in previous work we proposed a power index (PI) that
combines force, velocity, and time: PI = (Fₚₑₐₖ × vₐₙₖₗₑ) / tₑₓₑc. This index showed a high correlation
with expert coaches' evaluation (r=0.82). On the other hand, the static horizontal jump is a widely used
test to assess explosive power of the lower body in combat sports (Sáez de Villarreal et al., 2023).
Nevertheless, gross jump performance depends largely on body dimensions (height and limb length). To
control for this effect, horizontal efficiency indices have been proposed that normalize the jumped
distance by an anthropometric measure (Benítez et al., 2022). In this study, two variants were defined:
HEI₁ = HJ / leg length (hip height) and HEI₂ = HJ / height.
The objective of this study was to calculate these indices in a sample of 16 youth karateka, analyze
their relationships with PI and the underlying biomechanical variables, and discuss their practical utility
for coaches.
Materials and Methods
Sixteen male karateka participated, aged 16 to 19 years (mean 16.4 ± 0.8 years), holding black or brown
belts, with at least 4 years of practice and no injuries in the previous 3 months. All signed informed
consent forms.
Measurements:
· Static horizontal jump (HJ): From feet together, maximum forward jump. Best of three attempts
(cm). · Leg length (LL): Distance from the iliac crest to the lateral malleolus of the ankle (cm). · Height:
Total stature (cm). · Impact force (Fₚₑₐₖ): Dynamometer at 1000 Hz (N).
RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
101
Ankle linear velocity (vₐₙₖₗₑ): Camera at 240
fps (m/s). · Execution time (tₑₓₑc): From takeoff
to impact (s). · Hip angular velocity (ωₕᵢₚ): IMU
at 200 Hz (°/s).
Calculated indices:· PI = (Fₚₑₐₖ × vₐₙₖₗₑ) / tₑₓₑc
(N·m/s²) · HEI₁ = HJ / LL (dimensionless)·
HEI₂ = HJ / Height (dimensionless). Statistical
Analysis: Mean, standard deviation, coefficient of
variation (CV%). Pearson correlation between PI,
HEI₁, HEI₂, and biomechanical variables.
Multiple linear regression to identify predictors of
PI. Significance α=0.05. Software: Jamovi.
Results
Table 1.
Individual data and descriptive statistics of
anthropometric variables and horizontal
efficiency
Kara
teka
HJ
(cm)
Leg
Lengt
h (cm)
Heig
ht
(cm)
HEI₁
(HJ/
LL)
HEI₂
(HJ/
Heig
ht)
1
198
92
175
2.15
2
1.13
1
2
205
89
176
2.30
3
1.16
5
3
212
94
190
2.25
5
1.11
6
4
185
78
160
2.37
2
1.15
6
5
220
83
166
2.65
1
1.32
5
6
195
82
167
2.37
8
1.16
8
7
230
80
160
2.87
5
1.43
8
8
210
84
170
2.50
0
1.23
5
9
188
91
175
2.06
6
1.07
4
10
215
90
172
2.38
9
1.25
0
11
245
82
165
2.98
8
1.48
5
12
200
96
192
2.08
3
1.04
2
13
225
97
193
2.32
0
1.16
6
14
190
90
188
2.11
1
1.01
1
15
208
75
152
2.77
3
1.36
8
16
275
90
172
3.05
6
1.59
9
Mean
214
.4
87.1
172.
1
2.47
0
1.22
8
SD
26.
3
6.2
11.4
0.31
1
0.15
7
CV (%)
12.
3
7.1
6.6
12.6
12.8
Minimu
m
185
75
152
2.06
6
1.01
1
Maxim
um
275
97
193
3.05
6
1.59
9
Table 1 Analysis: The sample presents wide
variability in horizontal jump (HJ), with values
ranging from 185 cm to 275 cm (CV=12.3%),
highlighting participant 16 with exceptional
performance (275 cm). Leg length (mean 87.1
cm) and height (mean 172.1 cm) show low to
moderate dispersion (CV=7.1% and 6.6%
respectively), indicating a relatively homogeneous
group in terms of body dimensions. The
horizontal efficiency indices HEI₁ and HEI₂
present similar variability (CV≈12.7%), with
HEI₁ reaching the highest maximum value
(3.056) due to the combination of a very high HJ
with moderate leg length in participant 16. The
slightly higher coefficient of variation of HEI₁
(12.6%) compared to that of height suggests that
leg-relative efficiency better discriminates
individual differences than total height-relative
efficiency. These indices allow classification of
karateka into efficiency levels: low (HEI₂ 1.30),
with 7 of the 16 participants (43.7%) falling into
the high category, evidencing good relative
jumping ability in this group.
RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
102
Table 2.
Descriptive statistics of the power index
(PI) and biomechanical variables
Variable
Mean
SD
CV
(%)
Mini
mum
Maxi
mum
Fₚₑₐₖ (N)
2014
398
19.8
1450
2750
vₐₙₖₗₑ
(m/s)
7.9
1.2
15.2
5.8
9.9
tₑₓₑc (s)
0.33
0.0
5
15.2
0.25
0.42
ωₕᵢₚ (°/s)
812
134
16.5
620
1050
PI
(N·m/s²)
48270
105
40
21.8
3150
0
68500
Table 2 Analysis: PI presents the highest
variability (CV=21.8%), indicating that kick
power is highly sensitive to individual differences
in force, velocity, and coordination. Hip angular
velocity (ωₕᵢₚ) shows moderate dispersion
(CV=16.5%), suggesting that although all
participants achieve acceptable pelvic rotation,
important differences exist in the explosiveness
of that movement. Impact force and ankle
velocity show similar variability (≈15-20%),
reflecting the typical heterogeneity in non-elite
youth populations.
Table 3.
Pearson correlation matrix between indices
and biomechanical variables
Variable
PI
HEI₁
HEI₂
HJ (cm)
0.82**
0.96**
0.98**
Fₚₑₐₖ (N)
0.85**
0.64*
0.66*
vₐₙₖₗₑ (m/s)
0.81**
0.59*
0.61*
ωₕᵢₚ (°/s)
0.88**
0.70*
0.73*
tₑₓₑc (s)
-0.72**
-0.53
-0.55*
Table 3 Analysis: PI correlates very strongly
with hip angular velocity (r=0.88) and with
impact force (r=0.85), confirming that kick
power depends primarily on explosive pelvic
rotation and the capacity to generate high force at
impact.
The HEIs also associate significantly with
these variables, although with lower magnitude
(r≈0.60-0.73). The high correlation between
HEI₁ and HEI₂ (r=0.94, not shown in the table)
indicates they measure a similar construct, so in
practice the simpler one (HEI₂) may be chosen
without substantial loss of information. The
negative correlation of PI with execution time
(r=-0.72) reinforces the importance of
explosiveness: shorter execution time yields
greater power.
Multiple Linear Regression (Predictors of PI)
The final model (adjusted R² = 0.84, p < 0.001)
showed:
Predictor
β
t
p
ωₕᵢₚ (°/s)
0.71
5.92
< 0.001
Fₚₑₐₖ (N)
0.38
3.15
0.008
vₐₙₖₗₑ (m/s)
0.29
2.41
0.032
tₑₓₑc (s)
-0.31
-2.58
0.024
Hip angular velocity is the most important
predictor (β=0.71), reinforcing the need to
specifically train explosive pelvic rotation. HEI₁
and HEI₂ did not enter the model due to
collinearity with ωₕᵢₚ (r≈0.70), suggesting that
jump efficiency and hip rotation share common
neuromuscular mechanisms.
Discussion
This study is the first to propose and compare
two horizontal efficiency indices in youth
karateka, alongside a power index for the Ura
Mawashi Geri Jodan kick. The results show that
both HEIs correlate significantly with PI,
although with slightly lower magnitude than gross
HJ (r=0.82 vs r≈0.76-0.79). This is expected, as
normalization removes variability due to
anthropometry, which partly contributes to actual
performance.
RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
103
Comparison with literature: Benítez et al.
(2022), in a review on jump efficiency in team
sports, reported HEI₂ (HJ/height) values in
youth basketball players of approximately 1.15-
1.30, similar to ours (1.23).
In elite adult karateka, Sáez de Villarreal et al.
(2023) found HEI₂ values up to 1.45, slightly
higher than our maximum (1.599), indicating that
some of our participants (especially number 16
with 1.599) even exceed elite adult values.
This finding suggests that karateka 16
possesses exceptional jumping ability, likely
associated with favorable genetics or high-quality
specific training. Relationship with kick power:
The strong correlation between HEI and ωₕᵢₚ
(r≈0.70-0.73) suggests that horizontal jump
efficiency and the capacity to rotate the hip
rapidly share common neuromuscular
mechanisms, probably related to explosive hip
and knee extension (Acosta, 2024).
This has practical implications: unilateral
plyometric training, which improves HEI, could
also positively transfer to hip angular velocity in
the kick. Indeed, studies such as that of Sáez de
Villarreal et al. (2023) demonstrated that 6 weeks
of plyometric training significantly improved
horizontal jump and reduced inter-limb
asymmetries, which could translate into a more
powerful and balanced kick.
Which of the two HEIs is more
recommendable?
HEI₁ (HJ/LL): Is more specific to the kick
movement, as leg length directly influences the
moment of inertia and ankle linear velocity.
Additionally, it showed a slightly greater range
and a slightly higher correlation with ωₕᵢₚ (r=0.70
vs 0.73). HEI₂ (HJ/Height): Is more practical, as
height is a standard measure in any medical-sports
control.
Furthermore, it allows comparison with
studies from other disciplines that use this index.
Given the high correlation between both
(r=0.94), they can be used interchangeably
depending on the availability of anthropometric
data.
Limitations: Small sample size (n=16), males
only, cross-sectional design. Body composition
and biological maturation were not measured,
which could influence the indices. The presence
of an outlier (participant 16 with HJ=275 cm)
increases the mean and variance but reflects the
reality of interindividual variability in youth sports
performance.
Practical applications: Coaches can easily
calculate HEI₂ (HJ/height) and use it to:
• Classify karateka into efficiency categories:
low (<1.15), moderate (1.15-1.30), or high
(>1.30).
• Monitor the evolution of jump efficiency
throughout the season.
• Identify athletes with good jumping ability
but low efficiency (e.g., high HJ but very
tall), who could benefit from specific
relative strength training.
• Detect exceptional talents such as
participant 16 (HEI₂=1.599), whose
profile suggests high potential for sports
requiring explosive jumps and kicks.
Conclusions
The power index PI = (Fₚₑₐₖ × vₐₙₖₗₑ) / tₑₓₑc
is valid and sensitive for quantifying the power of
the Ura Mawashi Geri Jodan kick in youth
karateka. Hip angular velocity is its main
determinant.
The horizontal efficiency indices HEI₁
(HJ/leg length) and HEI₂ (HJ/height) are easy to
calculate, correlate moderately with PI, and
provide complementary information on
neuromuscular efficiency independent of
anthropometry.
RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
104
The use of HEI₂ (HJ/height) is recommended
for its simplicity and broad applicability in
training monitoring in dojos and karate schools.
Values above 1.30 indicate outstanding horizontal
efficiency.
References
Acosta, D. A. V. (2024). Programa de fuerza
explosiva para mejorar la patada mawashi geri
jodan. Ciencia y Educación, 5(9), 6-24.
https://cienciayeducacion.com/index.php/jo
urnal/article/view/516
Benítez, J. M., García, L., & Rodríguez, P. (2022).
Eficiencia de salto horizontal en jóvenes
deportistas: una revisión sistemática. Revista
Cubana de Medicina del Deporte, 14(2), 45-58.
https://revmedep.sld.cu/index.php/medep/i
ssue/view/61
Chaabene, H., Hachana, Y., Franchini, E.,
Mkaouer, B., & Chamari, K. (2015). Physical
and physiological profile of elite karate
athletes. Sports Medicine, 45(6), 829-850.
https://link.springer.com/article/10.1007/B
F03262297
Cleather, D. J., Olah, V., Vacek, J., & Stastny, P.
(2023). A systematic review of dynamic forces
and kinematic indicators of front and
roundhouse kicks across varied conditions and
participant experience. Sports, 11(8), 141.
https://www.mdpi.com/2075-
4663/11/8/141
Corcoran, D., Climstein, M., Whitting, J., & Del
Vecchio, L. (2024). Impact force and velocities
for kicking strikes in combat sports: A
literature review. Sports, 12(3), 74.
https://www.mdpi.com/2075-4663/12/3/74
Loturco, I., Nakamura, F. Y., Artioli, G. G.,
Kobal, R., Kitamura, K., Cal Abad, C. C., ... &
Franchini, E. (2018). Relationship between
lower limb muscle power and kick
performance in young karate athletes. Journal
of Sports Sciences, 36(5), 528-533.
https://jyx.jyu.fi/jyx/Record/jyx_123456789
_103278
Neto, O. P., Silva, L. A., & Magalhães, F. A.
(2021). Kinematic analysis of Ura Mawashi
Geri in elite karateka. Archives of Budo, 17,
123-131.
https://www.researchgate.net/journal/Intern
ational-Journal-of-Environmental-Research-
and-Public-Health-IJERPH-1660-4601
Rangel, E. S. (2025). Biomecánica de la Patada en
Gancho Ura Mawashi Geri en Karatekas de la
Selección de Venezuela. Revista Mucuties.
http://erevistas.saber.ula.ve/index.php/muc
uties/article/view/21928
Reyes Ramia, V. E., González García, I., Gómez
Rodríguez, K. R., & Mayo Abrahan, M. (2023).
Preparación técnico táctica en la ejecución de
la mawashi geri en los karatekas 13-15 años.
Revista Ciencia y Actividad Física, 10(1), 134-
146.
https://revistaciaf.uclv.edu.cu/index.php/rev
ista/article/view/165
Sáez de Villarreal, E., Suárez-Arrones, L.,
Requena, B., Haff, G. G., & Ferrete, C. (2023).
Plyometric training’s effects on young male
karatekas’ jump, change of direction, and
inter-limb asymmetry. Sports, 12(1), 1.
https://www.mdpi.com/2075-4663/12/1/1
Shashu, A. A. (2022). L’analyse du mouvement de
quelques variables mécaniques de la technique
«Mawashi geri»: etude de cas sur des seniors
karatéka des clubs (G. S. P-AMEL). Sport
System Magazine, 9(2), 937-950.
https://asjp.cerist.dz/en/article/182929
Silva, R. M., Ferreira, J., Badicu, G., Muracki, J.,
Pożarowszczyk-Kuczko, B., & Kawczynski,
A. (2025). The role of age, experience, and
physical fitness in technical performance in
karate: An observational analysis. Baltic
Journal of Health and Physical Activity, 17(1),
Article 7.
https://asjp.cerist.dz/en/article/182929
Valdés Cabrera, L. M., Quetglas González, Z.,
Tabares Arévalos, R. M., & Ruíz Viladón, R.
E. (2020). Análisis biomecánico de la patada
Mawashi Geri Jodan en el kárate-Do. Revista
RIAF Journal ISSN: 2953-6693 Vol – 4 No. 2, July 2026
105
PODIUM, 15(1), 111-126.
http://scielo.sld.cu/scielo.php
Conflict of Interest Statement: The authors of
this manuscript declare in confidence that the
report presented is original and declare no
conflicts of interest with the norms of the RIAF
Journal.
Author Contribution Statement: José Ignacio
Popa Guerra: Developed the theoretical
systematization on the study variable, the applied
empirical instruments, and the bibliographic
references.
Francisco Freyre Vázquez: Developed the
methodology and results of the research,
conducted the discussion and conclusions.
Argimiro Velázquez González: Conducted the
tabulation of instruments and their statistical
results.
