Effects of an 8-week core-strength program on smash accuracy in female badminton athletes

Shuzhen Ma; Yicen Zhong; Kim Geok Soh; Haili Feng; Huajun Hu; Xinzhi Wang; Jing Li

doi:10.37190/abb/224458

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Effects of an 8-week core-strength program on smash accuracy in female badminton athletes

Acta of Bioengineering and Biomechanics

Volume 28 (2026): Issue 2 (June 2026)

By: Shuzhen Ma, Yicen Zhong, Kim Geok Soh, Haili Feng, Huajun Hu, Xinzhi Wang and Jing Li

Open Access

|Oct 2026

Figures & Tables

Achievements of provincial badminton teams in China.

Table 1

Instruments used to measure smash performance

Variables	Measurement method	Instrument	Unit	Reference
In situ smash accuracy	Ball placement test	Colored string	Count	[10,11]
Jump smash accuracy	Ball placement test	Leopard smart shuttlecock throwing machine
Move smash accuracy	Ball placement test	Leopard smart shuttlecock throwing machine

Source: From Ref. [11].

Table 2

Validity of smash performance instruments

Item	Measurement method	Number of agreements	Relevance		Number of agreements	Relevance
Item	Measurement method	Number of agreements	I-CVI	Kappa	Number of agreements	I-CVI	Kappa
In situ smash accuracy	Ball placement test	5	0.833	0.816	6	1.000	1.000
Jump smash accuracy	Ball placement test	5	0.833	0.816	6	1.000	1.000
Move smash accuracy	Ball placement test	5	0.833	0.816	6	1.000	1.000

Table 3

Test-retest reliability of smash performance instruments (n = 40)

Variables	Measurement method	Intraclass correlation coefficient	95% confidence interval (CI)
Variables	Measurement method	Intraclass correlation coefficient	Lower bound	Upper bound
In situ smash accuracy	Ball placement test	0.771	0.569	0.878
Jump smash accuracy	Ball placement test	0.762	0.552	0.874
Move smash accuracy	Ball placement test	0.807	0.637	0.898

Table 4

Demographic characteristics

Demographic characteristics	Group	Mean value	Std. deviation	t	p-value
Age	EG	21.15	0.745	−0.740	0.464
Age	CG	21.40	1.314	−0.740	0.464
Height	EG	167.25	3.998	−1.298	0.127
Height	CG	168.95	3.410	−1.298	0.127
Weight	EG	57.85	4.815	−1.131	0.190
Weight	CG	59.15	4.977	−1.131	0.190
Training time	EG	9.65	1.954	−0.564	0.576
Training time	CG	10.00	1.974	−0.564	0.576

Note: EG, Experimental Group; CG, Control group.

Table 5

Comparing between groups for smash accuracy performance variables at baseline

Variable	Group	Mean value	Std. deviation	t	p-value
In situ smash accuracy	EG	0.68	0.125	1.021	0.314
In situ smash accuracy	CG	0.64	0.123	1.021	0.314
Jump smash accuracy	EG	0.68	0.064	−0.324	0.748
Jump smash accuracy	CG	0.69	0.123	−0.324	0.748
Move smash accuracy	EG	0.73	0.092	0.277	0.783
Move smash accuracy	CG	0.72	0.132	0.277	0.783

Note: EG, Experimental group; CG, Control group.

Table 6

Descriptive statistics of in situ smash accuracy between groups across the time

Variable	Group	Baseline		Posttest1		Posttest2
Variable	Group	Mean value	Std. deviation	Mean value	Std. deviation	Mean value	Std. deviation
In situ smash accuracy	EG	0.68	0.125	0.70	0.103	0.84	0.067
In situ smash accuracy	CG	0.64	0.123	0.69	0.121	0.71	0.105

Note: EG, Experimental group; CG, Control group.

Table 7

Results of GEE on in situ smash accuracy score

Variable	Source	Wald chi-square	df	p-value
In situ smash accuracy	Group	4.154	1	<0.05
	Time	61.997	2	<0.001
	Group * Time	11.933	2	<0.05
	Age^♦	0.01	1	0.919
	Training time^♦	0.005	1	0.943
	Height^♦	0.073	1	0.787
	Weight^♦	0.003	1	0.958

Note: df, degrees of freedom; ^♦, covariates.

Table 8

Within groups comparison of in situ smash accuracy mean scores across the time for different groups

Variable	Group	(I) time	(J) time	Mean difference (I–J)	SE	p-value	95% CI for difference		Effect size (d)
Variable	Group	(I) time	(J) time	Mean difference (I–J)	SE	p-value	Lower	Upper	Effect size (d)
In situ smash accuracy	EG	Posttest2	Posttest1	0.1350*	0.015	0.000	0.100	0.170	1.595
		Posttest2	Baseline	0.1600*	0.016	0.000	0.121	0.199
		Posttest1	Baseline	0.0250	0.017	0.434	−0.016	0.066
	CG	Posttest2	Posttest1	0.0150	0.022	1.000	−0.037	0.067	0.612
		Posttest2	Baseline	0.0700*	0.026	0.019	0.009	0.131
		Posttest1	Baseline	0.0550*	0.022	0.035	0.003	0.107

Note: ^*, the mean difference is significant at 0.05 level; EG, Experimental group; CG, Control group; SE, Standard error.

Table 9

Between groups comparison of mean score for in situ smash accuracy at three different times

Variable	Time	Mean difference (EG–CG)	SE	p-value	95% CI for difference		Effect size (d)
Variable	Time	Mean difference (EG–CG)	SE	p-value	Lower	Upper	Effect size (d)
In situ smash accuracy	Baseline	0.040	0.03818	0.295	−0.0348	0.1148	0.323
	Posttest1	0.010	0.03457	0.772	−0−0578	0.0778	0.089
	Posttest2	0.130*	0.02716	0.000	0.0768	0.1832	1.476

Note: *, the mean difference is significant at 0.05 level; EG, Experimental group; CG, Control group; SE, Standard error.

The mean score of *in situ* smash accuracy across time for both groups.

Table 10

Descriptive statistics of jump smash accuracy between groups across the time

Variable	Group	Baseline		Posttest1		Posttest2
Variable	Group	Mean value	Std. deviation	Mean value	Std. deviation	Mean value	Std. deviation
Jump smash accuracy	EG	0.68	0.064	0.72	0.083	0.84	0.060
Jump smash accuracy	CG	0.69	0.123	0.69	0.121	0.72	0.114

Note: EG, Experimental group; CG, Control group.

Table 11

Results of GEE on jump smash accuracy score

Variable	Source	Wald chi-square	df	p-value
Jump smash accuracy	Group	5.359	1	<0.05
	Time	69.413	2	<0.001
	Group * Time	34.962	2	<0.001
	Age^♦	0.303	1	0.582
	Training time^♦	1.536	1	0.215
	Height^♦	0.497	1	0.481
	Weight^♦	0.401	1	0.526

Note: df, degrees of freedom; ^♦, covariates.

Table 12

Within groups comparison of jump smash accuracy mean scores across the time for different groups

Variable	Group	(I) time	(J) time	Mean difference (I–J)	SE	p-value	95% CI for difference		Effect size (d)
Variable	Group	(I) time	(J) time	Mean difference (I–J)	SE	p-value	Lower	Upper	Effect size (d)
Jump smash accuracy	EG	Posttest2	Posttest1	0.120^*	0.013	0.000	0.088	0.152	2.579
		Posttest2	Baseline	0.165^*	0.016	0.000	0.126	0.204
		Posttest1	Baseline	0.045	0.019	0.060	−0.001	0.091
	CG	Posttest2	Posttest1	0.025	0.024	0.915	−0.033	0.083	0.253
		Posttest2	Baseline	0.030	0.020	0.408	−0.018	0.078
		Posttest1	Baseline	0.005	0.027	1.000	−0.059	0.069

Note: ^*, the mean difference is significant at 0.05 level; EG, Experimental Group; CG, Control group; SE, Standard Error.

Table 13

Between groups comparison of mean score for jump smash accuracy at three different times

Variable	Time	Mean difference (EG–CG)	SE	p-value	95% CI for difference		Effect size (d)
Variable	Time	Mean difference (EG–CG)	SE	p-value	Lower	Upper	Effect size (d)
Jump smash accuracy	Baseline	−0.010	0.030	0.740	−0.069	0.049	0.102
	Posttest1	0.030	0.032	0.349	−0.033	0.093	0.096
	Posttest2	0.125*	0.028	0.000	0.070	0.180	1.317

Note: *, the mean difference is significant at 0.05 level; EG, Experimental group; CG, Control group; SE, Standard error.

The mean score of jump smash accuracy across time for both groups.

Table 14

Descriptive statistics of move smash accuracy between groups across the time

Variable	Group	Baseline		Posttest1		Posttest2
Variable	Group	Mean value	Std. deviation	Mean value	Std. deviation	Mean value	Std. deviation
Move smash accuracy	EG	0.73	0.092	0.79	0.104	0.86	0.089
Move smash accuracy	CG	0.72	0.132	0.73	0.121	0.76	0.082

Note: EG, Experimental group; CG, Control group.

Table 15

Results of GEE on move smash accuracy score

Variable	Source	Wald chi-square	df	p-value
Move smash accuracy	Group	4.298	1	<0.05
	Time	22.44	2	<0.001
	Group * Time	5.895	2	<0.05
	Age^♦	0.279	1	0.597
	Training time^♦	0.777	1	0.378
	Height^♦	0.434	1	0.51
	Weight^♦	0.011	1	0.915

Note: df, degrees of freedom; ^♦, covariates.

Table 16

Within groups comparison of move smash accuracy mean scores across the time for different groups

Variable	Group	(I) time	(J) time	Mean difference (I–J)	SE	p-value	95% CI for difference		Effect size (d)
Variable	Group	(I) time	(J) time	Mean difference (I–J)	SE	p-value	Lower	Upper	Effect size (d)
Move smash accuracy	EG	Posttest2	Posttest1	0.07	0.033	0.106	−0.010	0.150	1.436
		Posttest2	Baseline	0.125*	0.028	<0.001	0.058	0.192
		Posttest1	Baseline	0.055*	0.023	0.049	0.000	0.110
	CG	Posttest2	Posttest1	0.035	0.023	0.368	−0.019	0.089	0.364
		Posttest2	Baseline	0.04	0.023	0.238	−0.015	0.095
		Posttest1	Baseline	0.005	0.013	1.000	−0.027	0.037

Note: *, the mean difference is significant at 0.05 level; EG, Experimental group; CG, Control group; SE, Standard error.

Table 17

Between groups comparison of mean score for move smash accuracy at three different times

Variable	Time	Mean difference (EG–CG)	SE	p-value	95% CI for difference		Effect size (d)
Variable	Time	Mean difference (EG–CG)	SE	p-value	Lower	Upper	Effect size (d)
Move smash accuracy	Baseline	0.010	0.035	0.776	−0.059	0.079	0.088
	Posttest1	0.060	0.035	0.084	−0.008	0.128	0.532
	Posttest2	0.095*	0.026	0.000	0.043	0.147	1.169

Note: *, the mean difference is significant at 0.05 level; EG, Experimental group; CG, Control group; SE, Standard error.

The mean score of move smash accuracy across time for both groups.

Table A1

Personal details of intervention training program experts

Organization	Title and Degree	Area for research
Tianjin Institute of Physical Education	Professor	Sports training
Guangxi Normal University	Professor	Physical education
Jiangxi University of Science and Technology	Associate professor	Physical education
Shanghai Institute of Physical Education	Doctor of Philosophy	Sport psychology
Ningxia Institute of Technology	Professor	Physical education
Nankai University	Badminton coach	Physical education

Expert information
Work unit
Full name
Title
Research area

Table A2

Core training intervention protocol

Duration (week)	Time (min)	Frequency (times/week)	Types	Sets	Repetition (time)	Rest (s)	Intensity
1–3	25	3	1-Abdominal bracing	40 s	3	60–90	Low-threshold training (50%–60%HRmax)
			2-Plank	40 s	3	60–90
			3-Left-side bridge	40 s	3	60–90
			4-Right-side bridge	40 s	3	60–90
4–5	25	3	1-Abdominal bracing	40 s	3	60–90	Intermediate- threshold training (55%–65%HRmax)
			2-Plank	40 s	3	60–90
			5-Russian twist	20 reps	3	60–90
			6-Lie on your back and alternate leg lifts	20 reps	3	60–90
			7-Lie on your back and roll your belly	20 reps	3	60–90
6–8	25	3	8-Dead bug	30 reps	3	60–90	High-threshold training (60%–70%HRmax)
			5-Russian twist	30 reps	3	60–90
			6-Lie on your back and alternate leg lifts	30 reps	3	60–90
			7-Lie on your back and roll your belly	30 reps	3	60–90
			10-Lie on your stomach and rise at both ends	30 reps	3	60–90

Table A3

Overall intervention protocol

Duration (week)	Frequency (times/week)	Process & Time		EG (Core training intervention)					CG (Routine training intervention-The standard training program of school)
Duration (week)	Frequency (times/week)	Process & Time		Content of Physical training	Sets	Repetition (time)	Rest (s)	Intensity	Content of Physical training	Sets	Repetition (time)	Rest (s)	Intensity
1–3	3	Warm up (10 min)		Move the wrist, shoulder, hip, knee, and ankle. (The standard training program of school)
		Intervention (25 min)		Abdominal bracing	40 sec	3	60–90	50–60% HRmax	Jog	40 sec	3	60–90	50–60% HRmax
				Plank	40 sec	3	60–90		Belly jump	20 reps	3	60–90
				Left side bridge	40 sec	3	60–90		high knee lift	40 sec	3	60–90
				Right side bridge	40 sec	3	60–90		Squat against the wall	40 sec	3	60–90
		Cool down (10 min)		Upper trapezius stretches, lunge with spinal twist, cobra pose, side split, sit and-reach (The standard training program of school)
4–5	3	Warm up (10 min)		Move the wrist, shoulder, hip, knee, and ankle. (The standard training program of school)
		Intervention (25 min)		Abdominal bracing	40 sec	3	60–90	55–65% HRmax	Jog	40sec	3	60–90	55–65% HRmax
				Plank	40 sec	3	60–90		Belly jump	20 reps	3	60–90
				Russian twist	20 reps	3	60–90		high knee lift	20 sec	3	60–90
		Lie on your back and alternate leg lifts	20 reps	3	60–90	Squat against the wall	40 sec		3	60–90
					Lie on your back and roll your belly		20 reps	3	60–90	Double run	20 sec	3		60–90
Cool down (10 min)			Upper trapezius stretches, lunge with spinal twist, cobra pose, side split, sit and-reach (The standard training program of school)
6–8	3	Warm up (10 min)		Move the wrist, shoulder, hip, knee, and ankle. (The standard training program of school)
		Intervention (25 min)		Dead bug		30 reps	3	60–90	60–70% HRmax	Jog	40 sec	3	60–90	60–70% HRmax
				Russian twist		30 reps	3	60–90		Belly jump	20 reps	3	60–90
				Abdominal rollout		30 reps	3	60–90		high knee lift	30 sec	3	60–90
				Plate alternation		30 reps	3	60–90		Squat against the wall	30 sec	3	60–90
				Lie on your stomach and rise at both ends		30 reps	3	60–90		Double run	20 sec	3	60–90
		Cool down (10 min)		Upper trapezius stretches, lunge with spinal twist, cobra pose, side split, sit and-reach (The standard training program of school)
Improvement suggestions

Table A4

Expert evaluation form for intervention measurement

Type	Relevance				Clarity				Improvement suggestions
Type	4	3	2	1	4	3	2	1	Improvement suggestions
Exercises selection
Duration
Frequency
Sets/Repetitions
Process and time
Rest/Recovery
Intensity
Content of warm-up
Content of cool down

Table A5

Instrument used to measure physical fitness

Variables	Measurement method	Instrument	Unit	Reference
Strength	Sit-ups	Stopwatch	Numbers	[39]
Power	Standing long jump	Meter rule	cm	[40]
Speed	Run 20 times with a low center of gravity	Stopwatch	s	[41]
Agility	The Illinois agility test (IAT)	Stopwatch	s	–
Endurance	Jumping rope	Stopwatch	Numbers	[42]
Balance	Y Balance Test (YBT)	YBT kit	cm	[43]
Stability	One-legged standing with eyes closed test	Stopwatch	s	[44]
Flexibility	Sit-and-reach	Sit-and-reach box	cm	[45]

Table A6

Instrument used to measure smash performance

Variables	Measurement method	Instrument	Unit	Reference
In situ smash accuracy	Ball placement test	Colored string. Leopard smart shuttlecock throwing machine.	Count	[11]
Jump smash accuracy	Ball placement test
Move smash accuracy	Ball placement test
In situ smash velocity	Ball speed test	Smart badminton sensor. Leopard smart shuttlecock throwing machine.	km/h
Jump smash velocity	Ball speed test
Move smash velocity	Ball speed test

Source: Ref. [11].

Table A7

Expert evaluation form for outcome measurement

Type	Relevance	Clarity	Improvement suggestions
	4	3	2	1	4	3	2	1
Strength test
Power test
Endurance test
Speed test
Agility test
Balance test
Stability test
Flexibility test
Smash accuracy test
Smash velocity test

Core training moves. (1) Abdominal bracing, (2) plank, (3) left-side bridge, (4) right-side bridge, (5) Russian twist, (6) lie on your back and alternate leg lifts, (7) lie on your back and roll your belly, (8) dead bug, (9) abdominal rollout, and (10) lie on your stomach and rise at both ends.

Run 20 times with a low center of gravity.

One-legged standing with eyes closed test.

References

Authors

Metrics

Articles in this issue

DOI: https://doi.org/10.37190/abb/224458 | Journal eISSN: 2450-6303 | Journal ISSN: 1509-409X

Journal RSS Feed

Language: English

Page range: 85 - 108

Submitted on: Jan 5, 2026

Accepted on: Jun 11, 2026

Published on: Oct 5, 2026

Published by: Wroclaw University of Science and Technology

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

Badminton,

Core strength training,

Female athletes,

Generalized estimating equations,

Smash accuracy

Related subjects:

Engineering,

Bioengineering and biomedical engineering,

Cellular and tissue engineering,

Biomechanics,

Medicine,

Biomedical engineering,

Materials sciences,

Biomaterials and natural materials

© 2026 Shuzhen Ma, Yicen Zhong, Kim Geok Soh, Haili Feng, Huajun Hu, Xinzhi Wang, Jing Li, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 28 (2026): Issue 2 (June 2026)

Effects of an 8-week core-strength program on smash accuracy in female badminton athletes

Figures & Tables

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