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Abstract

BACKGROUND:

Data about lower extremities’ strength and power asymmetries in fencers, and their relationships to fencing performance are limited and inconsistent.

OBJECTIVE:

The aim of the present study was to investigate asymmetries, between dominant (D) and non-dom (ND) legs of elite young male and female fencers, in relation to performance in fencing specific tests.

METHODS:

Anthropometric characteristics, unilateral vertical-horizontal jumping, isokinetic strength, lunge and step lunge performances were evaluated in 16 male and 22 female elite fencers.

RESULTS:

Significant differences between genders were found for all anthropometric measurements ( $p<$ 0.05). No significant bilateral asymmetries and gender x laterality effects were observed ( $p>$ 0.05). Fencing performance was negatively correlated with the D leg’s flexion/extension (F/E) ratio at 300 ${}^{\circ}$ /s (r: $-$ 0.564 to $-$ 0.619, $p<$ 0.05). In addition, D leg’s F/E ratio at 300 ${}^{\circ}$ /s was positively related to lung peak velocity and power in female fencers (r: 0.562–0.649; $p<$ 0.05). Finally, only in female fencers, unilateral triple hop distance was significantly related to lung peak velocity and power (r: 0.442–0.500; $p<$ 0.05).

CONCLUSIONS:

The results of the present study suggest that the differential activation/movement pattern of the D and ND leg muscles do not lead to anatomical, dynamic and functional lower extremities asymmetries.

Keywords

Isokinetic strength fencing step lunge

1. Introduction

Limb asymmetries, e.g. over 10–15% strength deficits between the limbs, are thought to be of clinical importance because they have been linked with increased risks for sports-related injuries [1, 2] and unsuccessful readiness of the injured athlete for return to training or competition [3]. Thus, monitoring the bilateral asymmetries is a way to prevent athletes’ injuries as well as to determine injured athletes’ readiness to participate again in sports events and training programs [3]. Unfortunately, the nature of many sports seems to promote bilateral asymmetries [4] as they have been repeatedly reported after power [1, 6] or strength-based evaluations [2, 6]. However, according to a recent systematic review [4] there is an inconsistency about the impact of bilateral asymmetry on physical and sport performances highlighting the need of further investigation in this topic.

Fencing is an Olympic sport in which athletes’ attacking success is highly dependent on technical and powerful forward unilateral lunges [7, 8, 9, 10]. During these lunges the upper limb movement is followed by the robust extension of the front knee, the dominant (D) leg, and the vigorous lengthening of the back leg, e.g. ND leg, during the push-of phase [11, 12]. Considering this kinetic chain there is a significant dissociation between the role of the front and rear leg [13]. It seems that ND leg knee extension muscles and triceps surae are activated firstly and they are responsible for the power/force production and transmission during the propulsive (concentric) action, while leg extensor and triceps surae of the D leg is responsible for the “braking” (eccentric phase), and stabilization of the leg, during this phase [14]. These significant differences between the actions and movement induced differential mechanical stresses between the front and rear legs during the attacking lunches, resulting in strong bilateral asymmetries between the two legs with a significant impact on fencing performance and injury risk [14]. However, data about the possible strength and power asymmetries between the lower extremities in fencers, and especially in young athletes, are limited and inconsistent [14, 15, 16, 17, 18] while the majority of the existing studies investigate mostly the anthropometrical-morphological asymmetries between the D and the ND legs of fencers, again with controversial results [8, 10, 14, 15, 17, 18]. Taking together the above, it is interesting to identify if fencing and its training routine may or may not lead to bilateral asymmetries of young athletes as well as to explore these asymmetries in relation to fencing performance.

Probably, the reason for the inconsistency about the presence of bilateral asymmetry between the D and the ND leg of fencers may rely on the different tests and methodologies that are widely used to detect these asymmetries. Until now, both open (mostly isokinetic dynamometers) and close (vertical and horizontal jumps) kinetic chain tests have been used for this evaluation. Closed kinetic chain tests can provide sports-specific data because they include stretch-shortening cycle and force production in high velocities, relative to those observed during the real movement executions [19]. In contrast, through open kinetic chain tests, peak and mean forces and flexion/extension muscle strength ratios (F/E ratio) could be retrieved, providing more accurate data about the strength status of each muscle-muscle groups [6, 16, 20]. However, these assessments require specific and costly equipment while they have low sport-related specificity. On the other hand, the limited data about lower limbs asymmetries in fencers, even if some studies adapt the same kinetic chain tests, are highly inconsistent and not allowing a precise and clear view on this issue [14, 15, 16, 17, 18]. Finally, to the best of our knowledge whether open and close kinetic chain tests provide the same results regarding the existence of muscles and/or limb asymmetries, has not been examined, at least with respect to this specific cohort.

The aim of the present study was hence to investigate the asymmetries between D and ND legs of elite young male and female fencers in relation to performance in fencing specific tests. It was hypothesized that the D and ND leg of elite young male and female fencers would be characterized by a significant asymmetry, negatively related to fencing performance.

2. Methods

2.1 Participants

Sixteen male (17.4 $\pm$ 4.3 years; body mass: 68.5 $\pm$ 14.1 kg; height: 175.0 $\pm$ 8.5 cm; D leg: 13 right and 3 left) and 22 female Greek fencers (16.5 $\pm$ 2.07 years; body mass: 60.9 $\pm$ 6.0 kg; height: 166.8 $\pm$ 6.7 cm; D leg: 18 right and 4 left) from the national Greek fencing team participated in this study. Participants’ characteristics are presented in Table 1. The inclusion criteria were: 1) absence of restraining orthopedic/neuromuscular maladies, 2) weight stability ( $\pm$ 2 kg) prior to entry ( $\sim$ 1 month), 3) absence of drugs abuse or medications which are known to affect performance, 4) members of their national team in their age categories and 5) absence of any participation in other sports or/and type of training, expect from fencing. Participants trained 5–6 times per week for approximately 12–15 hours and regularly participating in international (2–3) and national (16–20) competitions per year. All procedures were in accordance with the Declaration of Helsinki and approved by the School of Health Sciences, National and Kapodistrian University of Athens ethics committee while written parental consent forms were obtained prior to the entry of each athlete in the study, after a detailed written description of the procedures.

2.2 Design and procedures

The present cross-sectional study was conducted during the post-competition season (2 weeks after the yearly National Championship). All evaluations were performed after school, between 16.00–21.00. During the first and second visits in the Sports Excellent Lab, 1 ${}^{\text{st}}$ Orthopaedic Clinic, Attikon Hospital, Medical School, National and Kapodistrian University of Athens, all athletes performed the first familiarization session with the evaluations of power/strength/fencing performances, after they signed the informed consent. Three days later a second familiarization session was performed. One week later, they visited the laboratory for the third time, after at least 3 days of rest, for the evaluations of body composition, strength/power and fencing performances. Analytically, thirty minutes after reporting to the laboratory, each athlete underwent the anthropometric, body composition evaluations, while their lower extremity dominance was evaluated through the their fencing position. Then they performed a standard 20 minutes warm-up, including 10-min of jogging at their own pace and dynamic stretching activities of the upper and lower extremities. Thereafter, the evaluation of both lower extremities’ knee flexion/extension muscles isometric maximum strength was performed. Afterward jumping and fencing (through fencing specific tests) performances were evaluated, in that order. Between the tests, a 30 minutes rest interval was adapted, while each participant performed 2 sub-maximal and then 3 maximal attempts in each evaluation, with 3 minutes rest between attempts. Each fencer was thoroughly instructed and encouraged during each test.

2.3 Evaluations

2.3.1 Evaluation of body composition and anthropometric characteristics

Body height (HT) and sitting height (SH) was measured using a stadiometer with an accuracy of 0.5 cm (SECA 220, Seca Corporation, Columbia, USA). Leg length (LL) was estimated as HT minus SH. Arm span (AS) was evaluated as the distance between the tips of the middle fingers of both hands, placed against a wall, with both arms abducted at 90 ${}^{\circ}$ , elbows and wrists extended and palms facing forward. Body weight was measured with the use of a calibrated digital scale with an accuracy of $\pm$ 100 g (Seca 707, Seca Corporation, Columbia, USA). Body composition measurement was estimated according to the skinfold thickness method developed by Durnin and Rahaman [21]. The intraclass correlation coefficient (ICC) for body fat was 0.93, (95% CI: Lower $=$ 0.89, Upper $=$ 0.97), and for LBM 0.98, (95% CI: Lower $=$ 0.95, Upper $=$ 0.99; $p<$ 0.0001). Thigh muscles cross sectional area (CSA) was estimated with anthropometry and skinfold measurements [22]. Mid-thigh circumference was measured at a standing position with a plastic tape at the nearest 0.1 cm. Anterior mid-thigh skinfold was also measured [22]. Each skinfold was measured twice by the same investigator with a Harpenden skinfold caliper (CMS Weighing Equipment, London, UK), as close as 0.1 mm. Thigh CSA was estimated using the Housh multiple regression (HMR) equation: Total Thigh Muscle CSA: (4.68 $\cdot$ mid-thigh circumference in cm) – (0.64 $\cdot$ anterior thigh skinfold in mm) – 22.69 [22]. The ICC for this evaluation was 0.89 (95% CI: Lower $=$ 0.81, Upper $=$ 0.93, $n=$ 15.

2.3.2 Evaluation of maximum isokinetic lower extremities knee flexion and extension strength

All isokinetic strength tests were performed using a Biodex 4 (Model 2000, Multi-joint System 4 Pro, Biodex Corporation, Shirley NY, USA; sampling frequency 100 Hz) isokinetic dynamometer and the Biodex advantage software v4.63 (Biodex Corporation, Shirley, NY, USA), after a standard warm-up described in a previous section. Participant was placed on the seat, and the machine was adjusted according to manufacturer guidelines, for this evaluation. In each leg, after the execution of 3 submaximal efforts (knee flexion and extension), each participant performed 3 sets/efforts of five maximal consecutive extension and flexion movements of the knees joint, at three different angular velocities (60 ${}^{\circ}$ /s, 180 ${}^{\circ}$ /s and 300 ${}^{\circ}$ /s) in random order. The angular velocity of 60 ${}^{\circ}$ /s is frequently used for the determination of maximal peak moment and work, while the angular velocities of 180 ${}^{\circ}$ /s and 300 ${}^{\circ}$ /s are used for the evaluation of endurance and muscle power respectively [23]. Two minutes of rest was allowed between the trials of different angular velocities and 30sec between the 3 trials of each angular velocity. Flexion and extension peak moment from five maximal consecutive contractions in each trial were further used in statistics [24]. Range of motion in each trial ranged between 110 ${}^{\circ}$ (knee flexion) until 10 ${}^{\circ}$ (knee extension; 0 ${}^{\circ}$ is the full extension [24]. Participants were verbally encouraged to contract as hard as possible [25, 26]. Real-time visual feedback of the force applied was provided for each effort via a computer monitor placed just in front of each participant. Raw data of each participant were extracted from the Biodex 4 isokinetic dynamometer software and were further analyzed in Microsoft Excel sheet (Microsoft Corporation, USA), as it has previously described and proposed [25, 26, 27, 28, 29]. Data were then smothered using a low-pass, 4 ${}^{\text{th}}$ order, zero lag Butterworth digital filter, with a cut-off frequency of 25 Hz, and then the best performance in each trial according to the highest moment was further used [25, 26, 28]. In addition, flexion (PTF) and extension (PTE) moments were expressed relative to participants’ body mass (rPTF and rPTE respectively), while the ratio of flexion-extension peak moment was also calculated in each participant, both for the PTF/PTE (F/E ratio) and rPTF/rPTE (rF/E ratio) values. The ICCs of these tests have been evaluated in a pilot study ( $n=$ 10) and ranged between 0.91 (95% CI: Lower $=$ 0.86, Upper $=$ 0.93) and 0.92. (95% CI: Lower $=$ 0.88, Upper $=$ 0.96).

2.3.3 Jumping performance

For the evaluation of bilateral asymmetries during close kinetic chain movements, 2 types of jumps were used, including both horizontal and vertical actions, in random order. An optical measurement Optojump system was used for the evaluation of bilateral asymmetries during vertical type close kinetic chain movements. All participants performed 3 single-leg drop jumps in each leg (1 min rest between jumps and 3 min between legs), from a wooden box (height 20 cm), with their hands placed on hips. Prior to the execution of this test, participants were instructed to jump as quickly and as high as possible after landing, minimizing the contact time, while 2 warm-up jumpings were allowed before the maximum evaluations. The best performance based on jumping height was further used in statistics (ICC: 0.89–0.91; $p<$ 0.001). Triple hop test was also used for the evaluation of bilateral asymmetries during horizontal close kinetic chain movement. Again 3 efforts were allowed in each leg, with the same rest intervals, as they reported above, after 3 warm-up efforts, with hands akimbo. All efforts started from a standing position, and all participants were instructed to cover the longer distance, by performing three consecutive maximal hops on the same limb [30]. The best-recorded performance was further used in statistical analyses (ICC 0.94–0.96; $p<$ 0.001).

2.3.4 Lunge and step lunge performance

Fencing tests were conducted 30 min after the evaluation of jumping performance. Fencing specific tests were used for the determination of lunge velocity (LV) and step-lunge velocity (SLV) using the 1080 Quantum System (1080 Motion Inc., Stockholm, Sweden; 333 Hz sampling rate). During these tests, fencers standing on their own guard fencing position and holding their preferred weapon were tested while performing a lunge and a step-lunge with maximal effort and rhythm respectively. During the Lung test, all athletes from the fencing guard position performed an explosive extension of their armed hand followed by a lunge [18]. For the step-lunge test, again, fencers from their initial position performed an extension of their armored arm which followed by a step and then by a lunge [18]. The cable of the 1080 Quantum was attached in the fencing vest of each participant and all tests were performed three times with 3-min rest between efforts and tests. The best performance, according to the peak velocity that achieved, in each test was further used. The 1080 Quantum has been previously reported to have high validity and reliability in a similar evaluation [31]. The device was calibrated before each effort according to the manufacturer’s instructions. All the procedures were made on a fencing piste to mimic real-time fencing conditions as described recently [18]. Data retrieved directly from the official software of 1080 Quantum System. The test-retest reliability for the lunge and step-lunge tests were 0.90 and 0.91 respectively ( $p<$ 0.001).

2.4 Statistical analysis

Shapiro-Wilks test was used to assess data normality. No violations of normality distribution were found ( $p>$ 0.05). All data are presented as mean and standard deviation ( $\pm$ SD). Factorial ANOVA analysis was used in order to detect differences between genders and limbs (D and non- D) in all unilateral tests (Bonferroni Post-Hoc analysis where it was needed). Bilateral asymmetries, in all unilateral jumping tests, were estimated according to the equation: [(D Leg $-$ Non- D Leg) $\cdot$ (D Leg $+$ Non- D Leg) ${}^{-1}$ ] $\times$ 100 [32]. Independent $t$ -test was used for the determination of differences between genders in bilateral tests. Effect size, in each comparison, was determined by Cohen’s d according to the formula: (M1-M2) $\times$ SD ${}_{\textit{pooled}}^{-1}$ (small: 0.20–0.49, medium: 0.50–0.79, and large: $>$ 0.80). Pearson’s product-moment correlation coefficient was used to explore correlations between variables. Statistical analyses were performed with SPSS Statistics Ver. 20 (IBM Corporation, USA). $P\leqslant$ 0.05 was used as a 2-tailed level of significance.

Table 1
Characteristics of male ( $N=$ 16) and female ( $N=$ 22) young elite fencers

		AGE (years)	Body mass (kg)	Body fat (%)	Arm span (cm)	Height (cm)	Leg length (cm)	Cd (cm)	Cnd (cm)	CSAD (cm ${}^{2}$ )	CSAND (cm ${}^{2}$ )
MALE	Mean	17.4	68.5 ${}^{**}$	20.5 ${}^{*}$	181.4 ${}^{*}$	175.0 ${}^{*}$	86.5 ${}^{*}$	55.6	53.3	227.01	216.3
	SD	4.3	14.1	3.9	9.6	8.5	5.4	6.4	6.4	27.2	28.0
FEMALE	Mean	16.05	60.9	26.9	170.0	166.8	81.0	57.7	55.8	231.7	222.2
	SD	2.7	6.0	3.9	7.2	6.7	4.8	4.7	4.5	18.4	19.7

Cd: Circumference of D limb. Cnd: Circumference of ND limb. CSAD: Mid thigh cross sectional area of D limb. CSAND: Mid thigh cross sectional area of non D limb. ${}^{*}p=$ 0.001 and, ${}^{**}p=$ 0.03 male vs female.

Table 2

D (D) and ND (ND) legs performances in all unilateral test for male ( $N=$ 16) and female ( $N=$ 22) young elite fencers

		Triple hop (cm)				Drop jump (cm)				Lunge				Step lunge
		D		ND		D		ND		Peak velocity (m/s)		Peak power (W)		Peak velocity (m/s)		Peak power (W)
MALE	Mean	5.	64 ${}^{*}$	5.	46 ${}^{*}$	15.	713 ${}^{**}$	15.	797 ${}^{**}$	3.	55 ${}^{*}$	188.	72 ${}^{*}$	3.	98 ${}^{*}$	208.	12 ${}^{*}$
	SD	0.	53	0.	59	3.	55	3.	32	0.	69	54.	82	0.	92	82.	56
FEMALE	Mean	4.	49	4.	47	11.	97	12.	10	2.	68	102.	46	2.	99	112.	95
	SD	0.	59	0.	71	3.	82	2.	89	0.	68	42.	42	0.	64	37.	02
	d	2.	09	1.	53	$-$ 0.	19	$-$ 0.	04	1.	35	1.	47	1.	52	1.	67

${}^{*}p=$ 0.000 and ${}^{**}p=$ 0.01 for the comparison male vs female.

Table 3

Absolute and relative peak moments of D (D) and ND (ND) lower extremities in male ( $N=$ 16) and female ( $N=$ 22) young elite fencers

			Angular velocities
			60 ${}^{\circ}$ /s				180 ${}^{\circ}$ /s				300 ${}^{\circ}$ /s
			D		ND		D		ND		D		ND
Absolute peak moment (Nm)
Extension	Male	Mean	194.	98 ${}^{*}$	187.	94 ${}^{*}$	137.	98 ${}^{*}$	132.	93 ${}^{*}$	108.	91 ${}^{*}$	103.	73 ${}^{*}$
		SD	48.	96	49.	25	35.	96	30.	54	29.	35	18.	51
	FEMALE	Mean	139.	05	139.	64	98.	06	98.	07	76.	24	75.	95
		SD	26.	46	27.	38	19.	28	21.	13	13.	69	15.	87
	Cohen’s D males vs females		1.	53	1.	30	1.	49	1.	46	1.	55	1.	63
Flexion	Male	Mean	103.	53 ${}^{*}$	99.	24 ${}^{*}$	81.	09 ${}^{*}$	80.	56 ${}^{*}$	70.	33 ${}^{*}$	65.	09 ${}^{*}$
		SD	29.	58	25.	71	22.	72	19.	49	21.	61	15.	17
	FEMALE	Mean	73.	82	69.	51	57.	52	54.	96	49.	27	48.	85
		SD	12.	25	10.	89	12.	51	10.	68	10.	07	8.	61
	Cohen’s D males vs females		1.	44	1.	65	1.	38	1.	75	1.	45	1.	37
Relative peak moment (Nm/Kg)
Extension	Male	Mean	2.	94 ${}^{*}$	2.	88 ${}^{*}$	2.	09 ${}^{*}$	2.	05	1.	66 ${}^{*}$	1.	60 ${}^{*}$
		SD	0.	38	0.	50	0.	35	0.	32	0.	32	0.	28
	FEMALE	Mean	2.	33	2.	34	1.	67	1.	70	1.	28	1.	27
		SD	0.	31	0.	31	0.	43	0.	49	0.	18	0.	21
	Cohen’s D males vs females		1.	22	1.	39	1.	08	0.	84	1.	57	1.	40
Flexion	Male	Mean	1.	58 ${}^{*}$	1.	51 ${}^{*}$	1.	22 ${}^{*}$	1.	24 ${}^{*}$	1.	08 ${}^{*}$	1.	00 ${}^{*}$
		SD	0.	33	0.	29	0.	25	0.	23	0.	29	0.	19
	FEMALE	Mean	1.	24	1.	17	0.	96	0.	93	0.	83	0.	82
		SD	0.	16	0.	13	0.	17	0.	14	0.	16	0.	13
	Cohen’s D males vs females		1.	42	1.	49	$-$ 0.	11	0.	34	0.	37	0.	97

${}^{*}p=$ 0.000 and ${}^{**}p=$ 0.01 for the comparison male vs female.

Table 4

Significant correlations between fencing and dynamic, functional performance parameters in male ( $N=$ 16) and female ( $N=$ 22) young elite fencers, ( $p<$ 0.05)

Variables	Lunge peak velocity	Lunge peak power	Step lunge peak velocity	Step lunge peak power
	MALE
D leg F/E 300 ${}^{\circ}$ /s			$-$ 0.570	$-$ 0.619
D leg rF/E 300 ${}^{\circ}$ s ${}^{-}$			$-$ 0.564	$-$ 0.614
	FEMALE
D leg F/E 300 ${}^{\circ}$ /s	0.635	0.562	0.522	0.556
D leg rF/E 300 ${}^{\circ}$ s ${}^{-}$	0.649	0.568	0.532	0.557
Triple hop distance of D leg	0.445	0.446
Triple hop distance of ND leg	0.442	0.500

F/E: flexion-extension peak moment ratio. rF/E: flexion-extension peak moment ratio relative to body mass.

3. Results

Significant differences between genders were found for height, body mass, body fat, arm span and leg’s length ( $p<$ 0.05; Table 1). No significant differences were found, either for the comparison between the genders nor for the comparison between D and ND leg, for mid-thigh circumferences (MTC) and cross-sectional areas (CSA; $p>$ 0.05; Table 1).

Significant gender differences were found in unilateral drop jumps height for the D ( $p=$ 0.004, $d=$ $-$ 0.19) and the ND leg ( $p$ : 0.006, $d=$ $-$ 0.04 Table 2), as well as for both legs’ triple hop distance (D: $p$ : 0.000, $d=$ 2.09; ND: $p$ : 0.000, $d=$ 1.53; Table 2), with male athletes to achieve higher performances. Significant gender differences were observed for peak velocities and power production in lunge ( $p$ : 0.000; $d$ : 1.35 and 1.47 for velocity and power respectively) and step lunge ( $p$ : 0.000; $d$ : 1.52 and 1.67 for velocity and power respectively) fencing tests in favor of male athletes (Table 2). In addition, significant differences between male and female athletes were observed in all isokinetic tests (Table 3). Specifically, male athletes achieved higher absolute peak moments in all angular velocities in both D (Extension: $p<$ 0.001, $d$ : 1.53, 1.49, 1.55; Flexion: $p<$ 0.001, $d$ : 1.44, 1.38, 1.45 for 60, 180 and 300 ${}^{\circ}$ /s respectively) and ND legs (Extension: $p<$ 0.001, $d$ : 1.30, 1.46, 1.63; Flexion: $p<$ 0.001, $d$ : 1.65, 1.75, 1.37 for 60, 180 and 300 ${}^{\circ}$ /s respectively). Similarly, male athletes achieved higher relative to BW peak moments in all angular velocities in both D (Extension: $p<$ 0.001, $d$ : 1.22, 1.08, 1.57; Flexion: $p<$ 0.001, $d$ : 1.42, $-$ 0.11, 0.37 for 60, 180 and 300 ${}^{\circ}$ /s respectively) and ND legs (Extension: $p<$ 0.001, $d$ : 1.39, 0.84, 1.40; Flexion: $p<$ 0.001, $d$ : 1.49, 0.34, 0.97 for 60, 180 and 300 ${}^{\circ}$ /s respectively; Table 3). No significant differences were found for F/E and rF/E ratios, at any angular velocity ( $p>$ 0.05). No significant differences were found between D and ND legs in all cases (Bilateral asymmetries; $p>$ 0.05; Tables 2 and 3). No significant interaction between gender and laterality effects were found for drop jump ( $p=$ 0.65), triple hop ( $p=$ 0.56), absolute ( $p=$ 0.273–0.789), relative ( $p=$ 0.351–0.974) peak moments in all isokinetic tests and lunge and step lunge performances ( $p>$ 0.450; (Tables 2 and 3).

Step lunge peak velocity and power were negatively correlated with D leg’s F/E and rF/E ratios at 300 ${}^{\circ}$ /s in male fencers (r: $-$ 0.570 and r: $-$ 0.619 respectively, $p<$ 0.05; Table 4). In contrast, positive correlations were found between step lunge peak velocity, power, F/E and rF/E ratios at 300 ${}^{\circ}$ /s in male fencers (r: 0.522 and r: 0.557 respectively, $p<$ 0.05; Table 4). D leg’s F/E ratio at 300 ${}^{\circ}$ /s was positively related to lunge peak velocity and power in female athletes (r: 0.562–0.649; $p<$ 0.05; Table 4). Finally, only in female athletes, triple hop distance either of D or ND leg, was significantly related to lunge peak velocity and power (r: 0.442–0.500; $p<$ 0.05; Table 4).

4. Discussion

The main finding of the present study was the existence of symmetry between D and ND legs either in close or in open kinetic chain tests in young elite male and female fencers. In contrast, as it expected, significant gender differences were found in unilateral drop and triple jump, in isokinetic absolute and relative peak moments at all angular velocities for both legs and in fencing specific kinetic patterns (peak velocity and power of lunge and step and lunge) in favor of males. Finally, fencing specific performances were highly related to the extent of isokinetic knee muscles’ flexion/extension ratio during high angular velocities (300 ${}^{\circ}$ /s) as well as to performance in the unilateral triple hop test.

Fencing is characterized by close kinetic movements of the lower limbs in which knee flexors and extensors muscles of D and ND limb contract differently and not on the same phase during fencing assault [8, 9, 10, 11, 12, 13, 17, 18]. Indeed, during fencing training or competitions massive and repeated eccentric forces are applied at the final phase of lunge on the D limb while propulsive forces are produced from the ND limb during the initial phase of the lunge. Thus, these differential actions may lead to morphological, functional and dynamic asymmetries between the limbs as well as between each leg’s muscles as it has been previously reported [8, 9, 10, 13, 14, 15]. However, the results of the present study do not agree with these reports indicating the absence of any morphological, functional and dynamic asymmetries at least in elite young male and female fencers.

In the present study mid-thigh circumferences and crossectional areas of the D and ND leg did not differ either in male or female young fencers. Recently, significant differences between D or ND legs’ cross-sectional areas have been reported in moderate trained but not in elite fencers [14]. In addition, the observation of these asymmetries in cross-sectional areas of D and ND legs can strongly distinguish the elite from non-elite fencers [14]. Furthermore, mid-thigh crossectional area asymmetries between lower limbs have been reported only in adult fencers and not in the young athletes [18]. Thus, the absence of any asymmetries between lower limbs’ mid-thigh crossectional areas that were observed in the present study could be due to the young age and level (elite), verifying the previous reports [8, 14].

Until now only two studies investigated asymmetries in fencers using isokinetic strength evaluations [15, 16]. Males’ peak moment values at 60 ${}^{\circ}$ /sand 180 ${}^{\circ}$ /s of the present study were lower than those previously reported [15]. However, these differences can be easily explained since our participants were younger and less experienced in comparison to the Olympic level Swedish fencers who have participated the study of Nyström et al. [15]. The present study revealed no significant asymmetries between legs but only between genders in all angular velocities. This is in agreement with Poulis et al. [16], who showed significant differences only between elite and moderate trained fencers in all angular velocities (30 ${}^{\circ}$ /s, 60 ${}^{\circ}$ /s and 240 ${}^{\circ}$ /s). Furthermore, and in accord with Poulis et al. [16], no significant differences in F/E ratios were observed either within or between gender groups. Thus, the present study supports the observation that sports dominance does not necessarily induce asymmetries either between the limbs or within the muscle of each limp at least when asymmetries are evaluated thought isokinetic tests [16].

Unfortunately, the use of open kinetic chain tests only (their accuracy notwithstanding) fails to reflect the mechanical and metabolic demands of a close kinetic chain sport [4] like fencing. Therefore a more sport-specific approach using muscle contractions that incorporate the stretch-shortening cycle such as unilateral vertical and horizontal jumping tests [7, 20] might have provided a better insight of this issue [4]. Indeed, drop jump performance seems to be the stronger predictor of fencing performance compared to other types of strength and power performance tests [7, 8, 18] while it has been recently reported that after strength and conditioning programs with horizontal jumps fencing performance is significantly increased [33]. In the present study no significant asymmetries in unilateral drop and triple jump performances were found, both in elite male and female young fencers, observations that were in accord with that of the isokinetic test reinforcing the conclusion that the unilateral nature of fencing and the differential activation/movement pattern of the D and ND leg’s muscles do not lead to lower extremities’ asymmetries.

Furthermore, the current results agree with those of a previous study which indicated that in elite fencers there was an absence of any lower extremities’ performance asymmetries during vertical close kinetic chain test in contrast to sub-elite fencers where significant asymmetries were found [14]. Thus, considering all the above it seems that elite young male and female fencers are not characterized by any strength/power performance asymmetries in both open and close kinetic chain tests. However, if this is a genetic outcome or a specific training induced adaptation is something that should be further investigated.

Specific only to the female participants lunge and step lunge performances were significantly correlated with D and ND leg’s triple hope performances, a finding that shows that although both legs are characterized by different kinetic patterns during fencing they contribute equally to fencing performance. In contrast, these correlations were not found in male participants. Moreover, F/E ratios of D leg, during the high angular velocity effort (300 ${}^{\circ}$ /s) were positively correlated with lunge and step-lunge performances in female fencers but negatively in male young athletes. According to these results it seems that lower (significantly stronger knee extension muscles) F/E ratios in male fencers, and higher (almost equal strength between knee flexion-extension muscles) F/E ratios in male fencers are related to higher step lunge performances. The previously mentioned differential correlations indicated that young male and female fencers may rely on differential, biomechanical, but mostly physiological parameters, during their fencing efforts. Indeed, performances in explosive activities are highly affected by the muscle size, muscle fiber composition and the neural activation [25, 27, 29, 34, 35, 36]. However, the function of the nervous system (e.g. agonist muscle activation, antagonist muscle coactivation or inactivation, etc.) may have the most important contribution on gender-related differences in sports performances [37, 38], while the training-induced increases of muscle size and activation are significantly different between genders of this age [37, 38]. On the other hand, these correlations may also indicate that male athletes rely mostly on their D leg strength and musculature, mainly of the quadriceps, to stop/control their movement during the “braking” phase. On the other hand, women rely mostly on high power production. Unfortunately, a limitation of the present study was that eccentric knee flexion/extension muscles isometric maximum strength was not evaluated. Thus, the previously mentioned suggestion could not be verified from the data of the present study and future studies should investigate this conjecture. However, this conclusion may be supported by the fact that these correlations were found only during the isokinetic test with high angular velocities while significant correlations were found between triple hop and lung performance only in the female participants. In addition, during the triple hop test, as a close kinetic chain action which includes the stretch-shortening cycle and force production in high velocities, participants performance depends on high muscle power production and not on their maximum strength [30]. However, further exploration are needed to explain the correlations of this study, as well as examine the relationships between neuromuscular qualities, different forms of strength (isometric, concentric-eccentric contractions) and fencing performance (force plates) to provide additional information to the coaches that could lead to a design of more effective strength and conditioning training programs to maximize fencing performance.

5. Conclusion

The results of the present study suggest that in young male and female fencers the differential activation/movement pattern of the dominant, non-dominant leg’s muscles, and the lower extremities’ movement specificity of the fencing do not lead to anatomical, dynamic and functional lower extremities asymmetries.

Author contributions

CONCEPTION: PanagiotisKoulouvaris and Charilaos Tsolakis.

PERFORMANCE OF WORK: Vasiliki Drakoulaki, Nikolaos Kontochristopoulos, Theocharis Simeonidis, Evgenia Cherouveim and Olga Savvidou.

INTERPRETATION OR ANALYSIS OF DATA: Spyridon Methenitis, Vasiliki Drakoulaki, Nikolaos Kontochristopoulos, Theocharis Simeonidis, Evgenia Cherouveim and Olga Savvidou.

PREPARATION OF THE MANUSCRIPT: Spyridon Methenitis.

REVISION FOR IMPORTANT INTELLECTUAL CONTENT: Spyridon Methenitis, Evgenia Cherouveim, Panagiotis Koulouvaris and Charilaos Tsolakis.

SUPERVISION: Charilaos Tsolakis.

Ethical considerations

The present study was approved by the School of Health Sciences, National and Kapodistrian University of Athens ethics committee (Ref. Number: 24-7-2019/1819041221) while written parental consent forms were obtained prior to the entry of each athlete in the study, after a detailed written description of the procedures.

Funding

The authors report no funding.

Footnotes

Acknowledgments

We wish to thank the participants for their efforts and consistency throughout the study.

Conflict of interest

All authors report no conflict of interest. All experimental procedures used comply with local governmental laws for human subjects.

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Bilateral asymmetries in male and female young elite fencers in relation to fencing performance

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Methods

2.1 Participants

2.2 Design and procedures

2.3 Evaluations

2.3.1 Evaluation of body composition and anthropometric characteristics

2.3.2 Evaluation of maximum isokinetic lower extremities knee flexion and extension strength

2.3.3 Jumping performance

2.3.4 Lunge and step lunge performance

2.4 Statistical analysis

Table 1 Characteristics of male ( N = 16) and female ( N = 22) young elite fencers

4. Discussion

5. Conclusion

Author contributions

Ethical considerations

Funding

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Characteristics of male ( $N=$ 16) and female ( $N=$ 22) young elite fencers