The aim of the present study was to examine and determine the impact of asymmetry of muscle strength and power between the right and left lower limbs on running speed with changes of direction (multidirectional speed) in female football players. 20 right-footed elite female soccer players from the Ekstraliga participated in the study. Statistical analysis indicates that in running speed with change of direction in the 505 Right and 505 Left tests (group criterion: MVSLJ), players in the group with higher asymmetry (G2) achieved higher change-of-direction running speeds than those in the group with lower asymmetry (G1). A one-way ANOVA of running speeds between groups G1 and G2 (group criterion: PPLP) indicate statistically significant differences in running speed between groups in the Zigzag and 505 Right tests. Players in the group with higher asymmetry (G2) ran faster in the change-of-direction sections of the 505 Right. Based on the results collected during the study on the impact of differences in strength and power between the lower limbs on change-of-direction sprint speed in professional female soccer players, it was observed that players with smaller asymmetry achieved lower change-of-direction running speeds than those with greater asymmetry. Moreover, all observed significant differences in running speed tests between the analyzed groups were significantly correlated with the percentage differences in lower limb power within these groups.
Article
Impact of Lower Limb Muscle Strength and Power Asymmetry on Multidirectional Speed in Female Soccer Players
https://doi.org/10.21203/rs.3.rs-5301913/v1
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asymmetry
female soccer
multidirectional speed
change of direction speed
strength
power
Women's football is a discipline in which explosive, high-intensity motor activities—particularly acceleration and precise changes in running direction—often determine the outcome of a match [1, 2]. Additionally, the speed and accuracy of perception, anticipation, reaction, choice of action, and decision-making significantly influence the speed of movement on the field, both with and without the ball [3, 4].
Multidirectional speed encompasses straight-line running speed, speed with changes in running direction—including acceleration, lateral movements, deceleration, and backward running [5, 6]. It is largely determined by muscle strength and power of the lower limbs [3, 7]. In interpreting data on muscle strength and power of the lower limbs, the terminology "peak force" or "peak power" is used [8, 9]. Generating high values of peak force or power characterizes elite athletes [10] and correlates with levels of running speed [11, 12]. Relative strength and power are calculated using the formulas (N/kg FFM or W/kg FFM), meaning peak strength and power divided by body weight (BW) or fat-free mass (FFM) of the subject [13]. In female and male footballers, the magnitude of relative strength correlates with running speed during changes of direction [14, 15], sports performance level [16], and the magnitude of generated peak strength and power of the lower limbs [17]. In summary, the magnitude of muscle strength and power is crucial in the context of multidirectional speed, acceleration, sudden turns, and jumps that occur in football [18].
However, not only the muscle strength and power generated by a single limb can influence multidirectional speed, but also the imbalance of strength between the lower limbs, known as asymmetry. Strength and power asymmetry between limbs can result from practicing sports where movement involves engaging one side of the body or one limb more than the other [19, 20]. In sports disciplines like football, a preferred dominance of the lower limb (functional asymmetry) is evident; therefore, dynamic asymmetry can be expected [21]. A relationship has been observed between the level of strength asymmetry of the lower limbs and the occurrence of injuries in male players [22] and female players [11]. Current research aims to explain whether and how the occurrence of asymmetry affects an athlete's physical fitness [23, 24]. From the studies conducted so far, conclusive conclusions cannot be drawn [25]. The mere occurrence of asymmetry provides limited information about whether the difference in muscle strength and power between limbs has a detrimental effect on physical fitness, whether these differences should be corrected during training, and whether they can impair physical fitness and pose a problem in practicing a particular sport discipline.
Only a few researchers have described the relationship between asymmetry of muscle strength and power of the lower limbs and multidirectional speed in women who train football professionally [26, 27]. 27. Ascenzi et al. [27] did not detect significant relationships between jump asymmetry and multidirectional speed abilities. However, in the work of Bishop et al. [26], asymmetry in drop jump (DJ) height showed significant associations with multidirectional speed in female football players. Furthermore, higher levels of jump asymmetry were associated with reduced straight-line speed in young female football players [26].
In view of the lack of definitive data regarding the impact of asymmetry of muscle strength and power of the lower limbs, further research is necessary to precisely verify whether the difference in muscle strength and power between the lower limbs affects the multidirectional speed of female football players and whether there are differences in multidirectional speed between groups with varying degrees of muscle strength and power asymmetry. The aim of the present study was to examine and determine the impact of asymmetry of muscle strength and power between the right and left lower limbs on running speed with changes of direction (multidirectional speed) in female football players.
Participants
The tests were conducted in the Laboratory of Muscle Strength and Power and the sports hall of the Jerzy Kukuczka Academy of Physical Education in Katowice. Fifty right-footed female soccer players playing in the Ekstraliga participated in the study. Due to exclusion criteria introduced during the study, 20 players were excluded. Ultimately, the results obtained by 30 participants were analyzed (age=23±3 years; height=165.9±5.07 cm; body mass=57.58±5.09 kg; training experience=4±0.98 years; body fat percentage=15.68±3.7%; muscle mass=27.03±2.22 kg; lean body mass=48.45±3.73 kg).
The players were informed that they could withdraw from the experiment at any stage without giving a reason. The tests performed did not pose a health risk to the participants, and the study was non-invasive. Participation in the experiment was voluntary, and the players could withdraw at any stage. The research protocol was approved by the University Bioethical Committee for Research at the Jerzy Kukuczka Academy of Physical Education in Katowice (Bioethical Committee Resolution No. 3/2021), all participants signed informed consent forms and all experiments were performed in accordance with relevant guidelines and regulations.
Inclusion and Exclusion Criteria
Inclusion criteria for the study group were: participation in top-level league competitions in Poland, medical qualification confirming no neuromuscular and musculoskeletal disorders, at least 60% of matches played in the Ekstraliga over the past two years, female gender, regular menstrual cycle, and dominant right lower limb. Exclusion criteria were: dominant left lower limb, less than three years of training experience in the Ekstraliga, age below 20 years, movement apparatus injuries in the last twelve months, menstrual pain (self-reported).
Participants were asked to maintain their usual dietary habits and proper sleep hygiene throughout the study. They were also asked to avoid any supplements or stimulants 24 hours before the sessions. The participants were informed about the protocol and course of the study, and they provided written consent to participate.
Analytical Procedures and Research Methods
The percentage difference in relative strength and power between the lower limbs obtained from strength tests was determined using the following formula [28]:
MODULUS.NUMBER ((RLL÷LLL))x100
where: RLL – right lower limb; LLL – left lower limb
The Modulus.Number formula was used to avoid negative results and to assess only the difference in relative strength and power between the lower limbs, not the dominance of one of them. For further analysis, a randomization threshold was determined to divide into two groups - G1 - a group with lower asymmetry in muscle strength and power, and G2 - a group with greater asymmetry in muscle strength and power. The threshold value qualifying for the group was determined using the formula [29, 30]: MEAN+(0.2×SD). A result equal to or below the threshold defined group G1 "with lower asymmetry," and a result above the threshold defined group G2 "with greater asymmetry." It should be emphasized that the level of asymmetry in no way allows determining the strength and power results achieved by the players. Only the impact of differences in muscle strength and power between the lower limbs was examined. Depending on the test used to assess the strength and power of a single limb, different values were obtained. Therefore, some players were classified into group G1 or G2 depending on the test. The group sizes determined after the maximum vertical single-leg jumps test (MVSLJ) were (G1 n=14, G2 n=16), after the lateral single-leg jumps test (LSLJ ) (G1 n=14, G2 n=16), as well as peak power tests for leg press (PPLP) (G1 n=16, G2 n=14), and after the single-leg squat test (SLS) (G1 n=16, G2 n=14).
The material was collected in two measurement periods. These were the winter preparatory period (30 players divided into two groups of 15, the first group on days 1 and 4 of the week, the second group on days 2 and 5 of the week) and the summer period (20 players divided into two groups of 10, the first group on days 1 and 4 of the week, the second group on days 2 and 5 of the week). Each participant completed the same test protocol. During the informational session, participants were familiarized with the course of the physical fitness tests. A standardized warm-up protocol preceded each test session: 10 minutes of cycling on an ergometer with a cadence of 70-80 revolutions per minute and an external load allowing for a power output of 100 W, followed by two circuits consisting of: arm circles (forward and backward), forward bends, side bends, forward, side, and backward lunges, leg swings (forward, side, and backward), and squats, with 10 repetitions of each exercise. Then, to increase neuromuscular activation, each participant performed 2 repetitions of 5m acceleration, deceleration, jumps, and sprints.
On the first day of the measurement session, after the warm-up, the players performed speed tests. After a 15-minute break, they performed 10 repetitions of side lunges, forward lunges, backward lunges, and squats to maintain body temperature, followed by maximum power tests (1RM) on the Keiser Leg Press [PPLP] and Keiser Squat [SLS] devices according to the procedure described by Earle [31].
On the second day of the session, after the warm-up, participants conducted jump tests: maximum vertical single-leg jumps (MVSLJ ) and lateral single-leg jumps (LSLJ), as well as peak power tests for leg press (PPLP) and single-leg squat (SLS) with an external load of 50% 1RM. Before starting the exercise, the participants received a start signal (verbal command "GO") and began the exercise within 10 seconds. Each session was performed with a 72-hour rest period from resistance training at the same time of day (between 10:00 - 11:30).
Test on the Force Plate Platform ForceDecks FD4000 Dual Force Platforms (Vald, UK)
The protocol for the MVSLJ jump was as follows: participants, standing on the platform, after stabilizing the starting position on one leg, performed a downward swing, lowering the center of gravity, and a maximum upward jump, landing on the platform with the same leg (arm movement was allowed). The task was to jump as high as possible.
For the LSLJ jump: Participants, standing on the platform in the same position as during the vertical jump, performed a downward swing by lowering the center of gravity and a maximum lateral jump, landing next to the platform on the other leg. The task was to jump as far as possible. The highest value from three attempts in each jump was used for measurement. A 10-second break was applied between repetitions, and a 3-minute break between jumps on the right and left leg. A 3-5 minute rest break was applied between jump tests to allow for ATP and PCr recovery [32].
Maximal Strength Test 1 RM on Keiser Leg Press and Keiser Squat Pneumatic Devices
The test started with 5-10 repetitions with a load of 50% of body weight. For the next 3-5 repetitions, the load was increased to 120% of body weight [13]. The test, involving 3-5 attempts, aimed to determine the maximum muscle strength level of each participant. If a participant could perform 5 repetitions, they continued according to the Earle procedure; if they could not perform more than 5 repetitions, their 1RM was estimated using the formula (Baechle et al., 2008):
1RM=load×(1+0.333×number of repetitions)
Keiser Leg Press Test (Keiser, USA)
The test involved single-leg seated leg press (PPLP). The adjustable seated position protected the lower back, keeping it stabilized, allowing for better stretching of the gluteal muscles, making them more active during the exercise. The knee joint angle between the thigh and lower leg was 90°. The lower limb not involved in the test was bent at the knee joint next to the seat. The movement was performed through the full anatomical range [33, 34]. After the warm-up phase, participants performed familiarization sets: 2 times with the right lower limb (PKD), 2 times with the left lower limb (LKD) at 30% RM, and after a 1-minute break, proceeded to the test: 3 times with the right lower limb (PKD) and 3 times with the left lower limb (LKD) with a load of 50% RM. A 10-second break was applied between repetitions, and a 3-minute rest period between attempts with the right and left lower limbs [32].
Keiser A300 Squat Test (Keiser Corporation, USA) [SLS - Single-Leg Squat]:
The test started from a squat position, with a 90° angle between the thigh and lower leg, shoulders under the load arms, and hands holding the grips. The starting position was without external resistance. This means that the bar regulating the load arms was inserted so that the weight was felt only during the upward movement. The movement involved a rapid explosive extension of the knee from a single-leg squat with the trailing leg in the air with a 50% 1RM load. The same start command, rest breaks, and the number of repetitions in the warm-up and test were applied as in the previous protocol (Leg Press). The best result from 3 attempts was used for analysis.
Measurement of Change-of-Direction Speed
The measurement of change-of-direction speed was conducted using two tests: the 505 test [35, 36] and the Zigzag test [37]. The players performed each test twice, and the better result was used in the analysis. Between each attempt and test, the players had a 3-minute rest period to allow for adenosine triphosphate (ATP) and phosphocreatine (PCr) resynthesis [32]. The participants started from a standing position with their preferred foot forward, 0.3 meters behind the starting line.
In the 505 test, the player started 10 meters before the first timing gate to ensure they were at full speed upon passing through it. After passing through the gate, the player continued running for an additional 5 meters to a turning line marked on the ground. At the turning line, the player was required to place one foot on or behind the line and perform a single 180° change of direction. They then accelerated back and ran 5 meters back through the timing gate, completing the test (Figure 1). The total timed distance from the timing gate to the turning line and back was 10 meters. Each participant was thoroughly familiarized with the movement patterns and was required to perform two successful trials, executing the turn using both the right (dominant) and left foot. The 505 test has been frequently used to assess change-of-direction speed in soccer [35, 36].
In the Zigzag test, the course consisted of four 5-meter sections marked by cones set at an angle of 100° [37]. The player had to run a total distance of 20 meters, changing direction by 100° every 5 meters (Figure 2). The test was performed twice, and the best result was recorded. The Zigzag test requires alternating acceleration, deceleration, and changes of running direction, similar to match situations, and has been used to assess change-of-direction speed in elite female athletes [38, 39, 40].
Statistical Analysis
To address the research problem, empirical and exploratory analyses of a comparative and model nature were applied [41-43].
Since peak power and maximum concentric force values were expressed in values considering fat-free mass (FFM), the FFM value was calculated using the formula:
FFM=TBM−FM
where:
FFM - fat-free mass
TBM - total body mass
FM - fat mass
First, descriptive statistics (mean values, standard deviations, and coefficient of variation, as well as frequency tables) were used to define the resulting data matrices. Normality of variable distribution was checked using the Shapiro-Wilk test, and homogeneity of variance using Levene's test. The verification of differences between the analyzed variables in terms of the studied groups G1 and G2 was performed using one-way ANOVA. When statistically significant differences were found, post-hoc tests (Tukey HSD) were applied. A significance level of p<0.05 was assumed for the analyses. For the sake of clarity and confirmation of the obtained results, an additional effect size (ES) test - Cohen's d - was conducted, defined as the difference between means divided by the measure of data variability, specifically the standard deviation:
The effect size result was interpreted as small (> 0.2 and <0.5), moderate (≥ 0.5 and <0.8), or large (≥ 0.8) [44]. The relationship between percentage asymmetries in strength and power of lower limbs and speed test results in groups G1 and G2 was checked using Pearson's linear correlation coefficient. Depending on the coefficient size, correlations were considered small (0-0.29), moderate (0.30-0.49), large (0.50-0.69), and very large (0.70-0.89) (Mikołajec et al., 2022). In summary, a comprehensive analysis of statistical data was performed using the Statistica software, version 15 (StatSoft Polska Sp. z o.o.) and the Excel spreadsheet from Microsoft Office, version 2013 (Microsoft, Poland).
The one-way analysis of variance (ANOVA) revealed significant differences between groups G1 and G2 in terms of lower limb muscle strength and power asymmetry across all diagnostic tests (Table 1). The greatest variation was observed in the PPLP test (F:88.53; p < 0.01; ES:3.35), while the smallest variation was found in the MVSLJ muscle strength test (F: 44.47; p < 0.01; ES: 2.58).
| Group Asymmetry Percentage | F value | p value | ES |
|---|---|---|---|
| G1 [1.73%] vs. G2 [9.71%] – MVSLJ | 44.47 | 0.01 | 2.58 |
| G1 [1.43%] vs. G2 [10.85%] – LSLJ | 65.68 | 0.01 | 3.06 |
| G1 [1.88%] vs. G2 [11.76%] – PPLP | 88.53 | 0.01 | 3.35 |
| G1 [3.33%] vs. G2 [13.47%] – SLS | 81.53 | 0.01 | 3.25 |
| G1 – group with lower muscle strength and power asymmetry; G2 – group with higher muscle strength and power asymmetry; MVSLJ – maximal vertical single-leg jump; LSLJ – lateral single-leg jump; PPLP – peak power in leg press; SLS – single-leg squat | |||
Differences in Multidirectional Speed Between Groups G1 and G2 Determined by MVSLJ Test
An ANOVA comparing multidirectional running speeds across various tests between groups G1 and G2 (criterion: MVSLJ) revealed significant differences. Post-hoc tests were conducted for the differentiating variables (Table 2). Statistical analysis indicates that in running speed with change of direction in the 505 Right and 505 Left tests, players in the group with higher lower limb muscle strength asymmetry (G2) achieved higher change-of-direction running speeds than those in the group with lower asymmetry (G1).
| ANOVA | |||||
|---|---|---|---|---|---|
| Test | F value | p value | ES | ||
| 505 Right [m/s] | 4,98 | 0,04 | 2,77 | ||
| 505 Left [m/s] | 6,15 | 0,03 | 3,21 | ||
| Zigzag [m/s] | 0,49 | 0,49 | 0,21 | ||
| Post-hoc Test | |||||
| Test | G1 Speed [m/s] | G2 Speed [m/s] | p value | ||
| 505 Right [m/s] | 3.96 | 4.35 | 0.04 | ||
| 505 Left [m/s] | 3.59 | 4.25 | 0.04 | ||
| ES – effect size (partial eta squared) | |||||
Differences in Multidirectional Speed Between Groups G1 and G2 Determined by LSLJ Test
An ANOVA comparing running speeds across various tests between groups G1 and G2 (criterion: LSLJ) revealed no significant differences (505 Right [m/s], ES = 0,29; 505 Left [m/s], ES = 0,19; Zigzag [m/s], ES = 0,15).
Differences in Multidirectional Speed Between Groups G1 and G2 Determined by PPLP Test
A one-way ANOVA of running speeds between groups G1 and G2 (criterion: PPLP) was conducted, allowing for the rejection of the null hypothesis of no differences between groups for speeds obtained during the Zigzag and 505 Right tests. Post-hoc tests were performed for the differentiating variables (Table 3).
| ANOVA | |||||
|---|---|---|---|---|---|
| Test | F value | p value | ES | ||
| 505 Right [m/s] | 3,17 | 0,04 | 1,34 | ||
| 505 Left [m/s] | 0,50 | 0,49 | 0,27 | ||
| Zigzag [m/s] | 3,19 | 0,04 | 0,82 | ||
| Post-hoc Test | |||||
| Test | G1 Speed [m/s] | G2 Speed [m/s] | p value | ||
| 505 Right [m/s] | 4.02 | 4.21 | 0.04 | ||
| Zigzag [m/s] | 3.81 | 3.91 | 0.04 | ||
| ES – effect size (partial eta squared) | |||||
The results indicate statistically significant differences in running speed between groups in the Zigzag and 505 Right tests. Players in the group with higher asymmetry (G2) ran faster in the change-of-direction sections of the 505 Right (G1 = 4.02 m/s; G2 = 4.21 m/s) and Zigzag (G1 = 3.81 m/s; G2 = 3.91 m/s) tests.
Speed Achieved by Players in Groups G1 and G2 Determined by SLS Test
The one-way ANOVA for running speed between groups G1 and G2 (criterion: SLS) on various tests allowed rejection of the null hypothesis for the 505 Right and Zigzag tests. Post-hoc tests were performed for the differentiating variables (Table 4).
| ANOVA | |||||
|---|---|---|---|---|---|
| Test | F value | p value | ES | ||
| 505 Right [m/s] | 4,30 | 0,03 | 2,07 | ||
| 505 Left [m/s] | 0,12 | 0,73 | 0,09 | ||
| Zigzag [m/s] | 5,06 | 0,03 | 1,02 | ||
| Post-hoc Test | |||||
| Test | G1 Speed [m/s] | G2 Speed [m/s] | p value | ||
| 505 Right [m/s] | 3.97 | 4.25 | 0.03 | ||
| Zigzag [m/s] | 3.81 | 4.01 | 0.03 | ||
| ES – effect size (partial eta squared) | |||||
The results indicate statistically significant differences in running speed between groups in the Zigzag and 505 Right tests. Players in the group with higher asymmetry (G2) ran faster in the change-of-direction sections of the 505 Right (G1 = 3.97 m/s; G2 = 4.25 m/s) and Zigzag (G1 = 3.81 m/s; G2 = 4.01 m/s) tests.
Correlation Between Asymmetry Levels and Running Speeds Within Groups G1 and G2
Pearson correlation coefficients between lower limb muscle strength and power asymmetry levels and running speeds were calculated within groups G1 and G2.
When the division was made based on the results of the MVSLJ test, a decrease in running speed accompanying an increase in lower limb strength asymmetry was observed in the 505 Right test (r = − 0.39) and 505 Left test (r = − 0.41) within group G2. In groups divided according to the LSLJ test, no significant correlations were observed. After division according to the results of the PPLP test, in group G2, an increase in asymmetry level correlated with obtaining lower speeds in the 505 Right and Zigzag tests (r = − 0.67; r = − 0.67). In groups divided by the SLS criterion, it was observed that in group G2, as asymmetry increased, the speed achieved in the 505 Right and Zigzag tests decreased (r = − 0.66; r = − 0.71).
Numerous scientific studies have suggested a relationship between lower limb muscle strength and power and running speed. However, there is no scientific consensus on the impact of asymmetry in muscle strength and power between lower limbs on multidirectional speed [45, 46]. The aim of the present study was to examine the influence of lower limb muscle strength and power asymmetry, measured using the Single-Leg Vertical Jump, Single-Leg Lateral Jump, Vertical Jump, and Plyometric Jump tests, on change-of-direction running speed in the Zigzag and 505 tests among professional female soccer players.
Lockie et al. [47] reported varying levels of asymmetry in muscle strength and power between lower limbs depending on the jump test used (SLVJ, SLLJ, and single-leg forward jump), but did not find significant correlations between asymmetry and multidirectional speed. This suggests that lower limb muscle strength asymmetries ≤ 10% do not negatively affect multidirectional speed. Similarly, Bishop et al. [48] observed a positive relationship between times in multidirectional speed tests and asymmetry in SLVJ in 16-year-old soccer players. In another study by the same group, a relationship was noted between muscle strength asymmetries during single-leg drop jump (DJ) and times in change-of-direction speed tests in cricketers, but not in soccer players [48].
Analyzing the relationships between lower limb muscle strength asymmetry and speed abilities, Lockie et al. [47] divided participants into groups with greater and lesser asymmetry based on the percentage difference in muscle strength tests between limbs. No significant differences in times were observed between groups in multidirectional speed tests. Similarly, Işın et al. [49], after dividing participants into groups with asymmetry levels of < 5%, 5–10%, and > 10%, did not notice significant speed differences between groups in multidirectional speed tests. In the study by Bishop et al. [50], the group with low asymmetry was significantly faster in multidirectional speed tests than the group with greater jump strength asymmetry; however, after division according to SLVJ, no differences in running speed between groups were observed.
In the present study, no correlations were observed between the magnitude of asymmetry in muscle strength and power and change-of-direction running speed in the SLLJ, VJ, and PJ tests. Only a weak relationship was observed between asymmetry in the SLVJ test and running speed in the 505 test on the left lower limb. This suggests that greater asymmetry between limbs measured in the SLVJ test may be associated with lower running speed during change-of-direction running. A similar relationship was observed in studies by Michailidis et al. (2020) and Bishop et al. [51], where an increase in jump strength asymmetry positively correlated with decreased speed abilities in the 505 test in young soccer players.
In the study by Sariati et al. (2020), lower limb power asymmetries during unilateral leg press and their impact on running speed were analyzed in professional soccer players. The mean dynamic asymmetry was 4.6%. The power asymmetry between limbs did not significantly correlate with change-of-direction speed at a 90° angle, which is consistent with our results.
Based on the conducted study and literature data, it can be stated that muscle strength and power asymmetry correlates with speed in the 505 test on the left lower limb. However, other authors report that higher levels of asymmetry do not affect change-of-direction running speed [47, 49, 50, 53]. To resolve this discrepancy, studies involving larger samples of female soccer players are necessary.
To examine whether the level of asymmetry in muscle strength and power between limbs affects multidirectional speed, the studied group was divided into two subgroups with smaller and greater dynamic asymmetry. The division was performed four times based on the results of four tests assessing lower limb muscle strength and power. It was observed that players with greater asymmetry achieved higher running speeds during change-of-direction running than those with smaller asymmetry. In the change-of-direction running tests, it was noted that the group with greater asymmetry, identified using the SLLJ test, was faster in the 505 tests involving both the right and left lower limbs. Similarly, the group with greater asymmetry, identified using the VJ and PJ tests, achieved higher speeds in the 505 test involving the right lower limb and the Zigzag test. This may be due to the fact that with greater asymmetry, one limb may act more effectively, taking on the main role during changes of direction and re-acceleration [54], which may translate into higher speed when negotiating turns [55].
This result is consistent with the studies of Bishop et al. [51] conducted on professional soccer players. However, in studies by other authors who also divided groups based on different levels of lower limb muscle strength and power asymmetry, no significant differences were observed in multidirectional speed results between groups [47, 49].
In the next stage of analysis, we examined whether there are correlations between the level of lower limb muscle strength and power asymmetry in the studied groups and the achieved running speeds. After calculating the correlation coefficients separately in each of these two groups, 14 statistically significant correlations were observed.
Dividing into groups using the SLVJ test allowed us to observe a decrease in running speed in the 505 right and left lower limb tests with an increase in muscle strength asymmetry in the group with greater dynamic asymmetry.
Practical implications
The presented results may have practical applications. In addition to the development of speed-strength abilities, which is the main goal of strength training for female soccer players, it is worthwhile to include information about the magnitude of asymmetry in the training plan. Low-level asymmetry, not exceeding 15%, may be beneficial for multidirectional speed in sports such as soccer (Maloney, 2019; Bishop et al., 2022a).
Based on the results collected during the study on the impact of differences in strength and power between the lower limbs on change-of-direction sprint speed in professional female soccer players, the following conclusions were formulated:
- It was observed that players with smaller asymmetry achieved lower change-of-direction running speeds than those with greater asymmetry.
- All observed significant differences in running speed tests between the analyzed groups were significantly correlated with the percentage differences in lower limb power within these groups.
Disclosure statement
No potential conflict of interest was reported by the authors.
Author Contribution
Conceptualization, DS, MP and AM; methodology, DS, PMP, MK, KŁ, PA, AM; software, MK , MS and AM.; validation, DS, MS, MP and PA; formal analysis, DS, AM; investigation, DS, MP and MK; resources, KŁ, MS, and AM; writing—original draft preparation, DS, MP, MS, KŁ and AM; writing—review and editing, MK and AM; supervision, PA, DS and MS; project administration, DS, MP and AM.The datasets used and analysed during the current study available from the corresponding author on reasonable request. [email protected]
Data Availability
The datasets used and analysed during the current study available from the corresponding author on reasonable [email protected]
- Datson, N., Drust, B., Weston, M., Jarman, I. H., Lisboa, P. J. & Gregson, W. Match physical performance of elite female soccer players during international competition. J. Strength. Cond. Res. 31, 2379–2387, DOI: 10.1519/JSC.0000000000001575 (2017).
- Scott, D., Haigh, J., & Lovell, R. Physical characteristics and match performances in women’s international versus domestic-level football players: a 2-year, league-wide study. Sci. Med. Football. 4, 211–216, DOI: 10.1080/24733938.2020.1745265 (2020).
- Chmura, P., Konefal, M., Andrzejewski, M., Kosowski, J., Rokita, A., Chmura, J. & Chmura, J. Analysis of motor activities of professional soccer players during the 2014 World Cup in Brazil. J. Hum. Kinet 56, 187–195, DOI: 10.1515/hukin-2017-0036 (2017).
- Sarmento, H., Anguera, M. T., Pereira, A. & Araújo, D. Talent identification and development in male football: a systematic review. Sport.s Med. 48, 907–931, DOI: 10.1007/s40279-017-0851-7 (2018).
- Dos'Santos, T., Thomas, C., Comfort, P. & Jones, P. A. The effect of angle and velocity on change of direction biomechanics: an angle-velocity trade-off. Sports. Med. 48, 2235–2253, DOI: 10.1007/s40279-018-0968-3 (2018).
- Lockie R.G., Schultz A.B., Callaghan S.J. & Jeffriess M.D. The effects of traditional and enforced stopping speed and agility training on multidirectional speed and athletic function. J. Strength. Cond. Res. 28(6), 1538–1551, DOI:10.1519/JSC.0000000000000309 (2014)
- Suchomel, T. J., Nimphius, S. & Stone, M. H. The importance of muscular strength in athletic performance. Sports. Med. 46(10), 1419–1449, DOI: 10.1007/s40279-016-0486-0 (2016).
- van der Kruk E., van der Helm F.C.T., Veeger H.E.J. & Schwab AL. Power in sports: a literature review on the application, assumptions, and terminology of mechanical power in sport research. J. Biomech. 79, 1–14, DOI: 10.1016/j.jbiomech.2018.08.031 (2018)
- Jiménez-Reyes, P., Samozino, P., Brughelli, M. & Morin, J. B. Effectiveness of an individualized training based on force-velocity profiling during jumping. Front Physiol 7, 677, DOI: https://doi.org/10.3389/fphys.2016.00677 (2017).
- Morin, J. B. & Samozino, P. Interpreting power-force-velocity profiles for individualized and specific training. Int. J. Sports. Physiol. Perform. 11(2), 267–272, DOI: 10.1123/ijspp.2015-0638 (2016).
- Prudholme, D. C., Coburn, J. W., Lynn, S. K., & Lockie, R. G. Relationships Between Sprint, Acceleration, and Deceleration Metrics with Training Load in Division I Collegiate Women's Soccer Players. J. Hum. Kinet. 85, 53–62, DOI: 10.2478/hukin-2022-0109 (2023).
- Haugen TA, Breitschädel F, Seiler S. Sprint mechanical variables in elite athletes: are force-velocity profiles sport specific or individual? PLoS One. 14, e0215551, DOI: 10.1371/journal.pone.0215551 (2019).
- Moir, G. L. Strength and conditioning: a biomechanical approach. Jones & Bartlett Learning. ISBN:9781284034844 (2015).
- Beato, M., Bianchi, M., Coratella, G., Merlini, M. & Drust, B. A single session of straight line and change-of-direction sprinting per week does not lead to different fitness improvements in elite young soccer players. J. Strength. Cond. Res. 36(2), 518-524, DOI: 10.1519/JSC.0000000000003369 (2022).
- Comfort, P., Stewart, A., Bloom, L., & Clarkson, B. Relationships between strength, sprint, and jump performance in well-trained youth soccer players. J Strength Cond Res 28(1), 173-177, DOI: 10.1519/JSC.0b013e318291b8c7 (2014).
- Śliwowski, R., Paillard, T., Bojkowski, Ł., Dudziński, W., Patek, M., & Marynowicz, J. Intra- and inter-limb strength imbalance and asymmetry in soccer: A comparison of elite senior and junior players. PLoS One. 19(4), e0302474. DOI: 10.1371/journal.pone.0302474 (2024).
- Thomas, C., Comfort, P., Chiang, C. Y. & Jones, P. A. Relationship between isometric mid-thigh pull variables and sprint and change of direction performance in collegiate athletes. J. Trainol. 4, 6–10, DOI: 10.17338/trainology.4.1_6 (2015).
- Seitz, L. B., Reyes, A., Tran, T. T., de Villarreal, E. S. & Haff, G. G. Increases in lower-body strength transfer positively to sprint performance: a systematic review with meta-analysis. Sports Med. 44(12), 1693–1702, DOI: 10.1007/s40279-014-0227-1 (2014).
- Hart, N. H., Nimphius, S., Weber, J., Spiteri, T., Rantalainen, T., Dobbin, M. & Newton, R. U. Musculoskeletal asymmetry in football athletes: a product of limb function over time. Med. Sci. Sports Exerc.. 48(7), 1379-87, DOI: 10.1249/MSS.0000000000000897 (2016).
- Fort-Vanmeerhaeghe, A., Bishop, C., Buscà, B., Aguilera-Castells, J., Vicens-Bordas, J., & Gonzalo-Skok, O. Inter-limb asymmetries are associated with decrements in physical performance in youth elite team sports athletes. PloS One. 15(3), e0229440. DOI: 10.1371/journal.pone.0229440 (2020).
- Maloney, S. J. he Relationship Between Asymmetry and Athletic Performance: A Critical Review.. J. Strength. Cond. Res. 33(9), 2579–2593, DOI: 10.1519/JSC.0000000000002608 (2019).
- van Melick, N., Meddeler, B. M., Hoogeboom, T. J., Nijhuis-van der Sanden, M. W. G. & van Cingel, R. E. H. How to determine leg dominance: The agreement between self-reported and observed performance in healthy adults. PLoS One 12(12), e0189876, DOI: 10.1371/journal.pone.0189876 (2017).
- Kalata, M., Hank, M., Bujnovský, D., Michálek, J., Varjan, M., Kunzmann, E., Zahálka, F., & Maly, T. Bilateral Strength Asymmetry in Elite Youth Soccer Players: Differences between Age Categories. Symmetry. 13(11). 1982. 10.3390/sym13111982. (2021).
- Dos'Santos, T., Bishop, C., Thomas, C., Comfort, P. & Jones, P. A. The effect of limb dominance on change of direction biomechanics: a systematic review of its importance for injury risk. Phys Ther Sport 37, 179-189, DOI: 10.1016/j.ptsp.2019.04.005 (2019).
- Bishop, C., Read, P., Chavda, S., Jarvis, P. & Turner, A. Asymmetries of the lower limb: the calculation conundrum in strength training and conditioning. Strength Cond. J. 38(6), 27-32, DOI: 10.1519/ssc.0000000000000264 (2016).
- Bishop, C., Brashill, C., Abbott, W., Read, P. & Turner, A. Jumping asymmetries are associated with speed, change of direction speed, and jump performance in elite academy soccer players. J. Strength. Cond. Res. 35(7), 1841–1847, DOI: 10.1519/JSC.0000000000003058 (2021).
- Ascenzi, G., Filetti, C., Di Salvo, V., Nuñez, F. J., Suarez-Arrones, L., Ruscello, B., Francioni, F. M., & Villanueva, A. M. Inter-limb asymmetry in youth elite soccer players: Effect of loading conditions. PloS One. 17(6), e0269695. DOI: 10.1371/journal.pone.0269695 (2022).
- Madruga-Parera, M., Bishop, C., Beato, M., Fort-Vanmeerhaeghe, A., Gonzalo-Skok, O., & Romero-Rodríguez, D. Relationship Between Interlimb Asymmetries and Speed and Change of Direction Speed in Youth Handball Players. J. Strength. Cond. Res. 35(12), 3482–3490. DOI: 10.1519/JSC.0000000000003328 (2021).
- Lockie, R. G., Jeffriess, M. D., Schultz, A. B., Callaghan, S. J., & Berry, S. P. The effects of traditional and enforced stopping speed and agility training on multidirectional speed and athletic performance. J. Strength. Cond. Res. 28(6), 1538–1551. DOI: 10.1519/JSC.0000000000000300 (2014).
- Dos’Santos, T., Thomas, C., Comfort, P., & Jones, P. A. The effect of angle and velocity on change of direction biomechanics: An angle-velocity trade-off. Sports Med. 48(10), 2235–2253. DOI: 10.1007/s40279-018-0968-3 (2018).
- Earle, R. Essentials of Strength Training and Conditioning, 2E. (2000).
- Ammar, A., Chtourou, H., Trabelsi, K., Padulo, J. ., Turki, M., El Abed, K., Hakim, A. Temporal specificity of training: Intra-day effects on biochemical responses and Olympic-Weightlifting performances. J. Sports. Sci.33(4), 358–368, DOI: 10.1080/02640414.2014.944559 (2014).
- Fielding, R. A., LeBrasseur, N. K., Cuoco, A., Bean, J., Mizer, K., & Fiatarone Singh, M. A. High-velocity resistance training increases skeletal muscle peak power in older women. J. Am. Geriatr. Soc. 50(4), 655–662. DOI: 10.1046/j.1532-5415.2002.50159.x (2002).
- Callahan, D., Phillips E., Carabello, R. , Frontera, W.R., Fielding, R.A. Assessment of lower extremity muscle power in functionally-limited elders, Aging Clin. Exp. Res. 19(3),194-9. DOI: 10.1007/BF03324689. (2007).
- Sheppard, J. & Young, W. Agility Literature Review: Classifications, Training and Testing. J. Sport Scie. 24. 919-32. DOI: 10.1080/02640410500457109 (2006).
- Draper, JA and Lancaster, MG. The 505 test: A test for agility in the horizontal plane. Aust J Sci Med Sport 17: 15-18, 1985
- Little, T., & Williams, A. G. Specificity of acceleration, maximum speed, and agility in professional soccer players. J. Strength Cond. Res. 19(1), 76–78. DOI: 10.1519/14253.1 (2005).
- Nimphius, S., McGuigan, M. R., & Newton, R. U. Relationship between strength, power, speed, and change of direction performance of female softball players. J. Strength Cond. Res. 24(4), 885–895. DOI: 10.1519/JSC.0b013e3181d4d41d (2010).
- Freitas, T. T., Alcaraz, P. E., Calleja-González, J., Arruda, A. F. S., Guerriero, A., Kobal, R., Reis, V. P., Pereira, L. A., & Loturco, I. Differences in Change of Direction Speed and Deficit Between Male and Female National Rugby Sevens Players. J. Strength Cond. Res. 35(11), 3170–3176. DOI: 10.1519/JSC.0000000000003195 (2021).
- Fischerova P, Krosta R, Gołaś A, Terbalyan A,Nitychoruk M, & Maszczyk A. Effect of power on agility, linear speed and change of direction deficit in female soccer players. Phys Activ Rev. 9(1): 109-116. doi: 10.16926/par.2021.09.13 (2021).
- Maszczyk, A., Zając, A. & Ryguła, I. A neural network model approach to athlete selection. Sports Eng. 13, 83–93 DOI: 10.1007/s12283-010-0055-y (2011).
- Maszczyk, A., Roczniok, R., Waśkiewicz, Z., Czuba, M., Mikołajec, K., Zajac, A., & Stanula, A. Application of regression and neural models to predict competitive swimming performance. Percept. Mot. Skills, 114(2), 610–626. DOI: 10.2466/05.10.PMS.114.2.610-626 (2012).
- Maszczyk, A., Gołaś, A., Pietraszewski, P., Roczniok, R., Zając, A., Stanula, A. Application of Neural and Regression Models in Sports Results Prediction. Procedia Soc. Behav. Sci. 117, 482-487. (2013).
- Cohen, J. Statistical Power Analysis for the Behavioral Sciences (2nd ed.). Routledge. DOI: 10.4324/9780203771587 (1988).
- Bishop, C., Turner, A., & Read, P. Effects of inter-limb asymmetries on physical and sports performance: a systematic review. J. Sports Sci. 36(10), 1135–1144. DOI: 10.1080/02640414.2017.1361894 (2018).
- Maloney, S. J., Richards, J., Nixon, D. G., Harvey, L. J., & Fletcher, I. M. Do stiffness and asymmetries predict change of direction performance?. J. Sports Sci. 35(6), 547–556. DOI: 10.1080/02640414.2016.1179775 (2017).
- Lockie, R. G., Callaghan, S. J., Berry, S. P., Cooke, E. R., Jordan, C. A., Luczo, T. M., & Jeffriess, M. D. Relationship between unilateral jumping ability and asymmetry on multidirectional speed in team-sport athletes. J. Strength Cond. Res. 28(12), 3557–3566. DOI: 10.1519/JSC.0000000000000588 (2014).
- Bishop, C., Read, P., Lake, J., Loturco, I., Dawes, J., Madruga, M., Romero-Rodrigues, D., Chavda, S., & Turner, A. Unilateral Isometric Squat: Test Reliability, Interlimb Asymmetries, and Relationships With Limb Dominance. J. Strength Cond. Res. 35(Suppl 1), S144–S151. DOI: 10.1519/JSC.0000000000003079 (2021).
- Işın, Ali & Akdağ, Eren & Çetin Özdoğan, Emel & Bishop, Chris. Associations between differing magnitudes of inter-limb asymmetry and linear and change of direction speed performance in male youth soccer players. Biomed. Hum. Kinet. 14. 67-74. DOI: 10.2478/bhk-2022-0009. (2022).
- Bishop, C., Read, P., Bromley, T., Brazier, J., Jarvis, P., Chavda, S., & Turner, A. The Association Between Interlimb Asymmetry and Athletic Performance Tasks: A Season-Long Study in Elite Academy Soccer Players. J. Strength Cond. Res. 36(3), 787–795. DOI: 10.1519/JSC.0000000000003526 (2022).
- Bishop, C., Read, P., McCubbine, J., & Turner, A. Vertical and Horizontal Asymmetries Are Related to Slower Sprinting and Jump Performance in Elite Youth Female Soccer Players. J. Strength Cond. Res. 35(1), 56–63. DOI: 10.1519/JSC.0000000000002544 (2021).
- Sariati, D., Hammami, R., Chtara, M., Zagatto, A., Boullosa, D., Clark, C. C. T., Hackney, A. C., Granacher, U., Souissi, N., & Zouhal, H. Change-of-Direction Performance in Elite Soccer Players: Preliminary Analysis According to Their Playing Positions. Int J Environ Res Public Health. 17(22), 8360. DOI: 10.3390/ijerph17228360 (2020).
- Loturco, I., Pereira, L. A., Kobal, R., Abad, C. C. C., Rosseti, M., Carpes, F. P., & Bishop, C. Do asymmetry scores influence speed and power performance in elite female soccer players?. Biol. Sport. 36(3), 209–216. DOI: 10.5114/biolsport.2019.85454 (2019).
- Yoshioka, S., Nagano, A., Hay, D. C., & Fukashiro, S. The effect of bilateral asymmetry of muscle strength on jumping height of the countermovement jump: a computer simulation study. J. Sports Sci. 28(2), 209–218. DOI: 10.1080/02640410903428566 (2010).
- Pardos-Mainer, E., Casajús, J. A., Bishop, C., & Gonzalo-Skok, O. Effects of Combined Strength and Power Training on Physical Performance and Interlimb Asymmetries in Adolescent Female Soccer Players. Int. J. Sports Physiol. Perform. 15(8), 1147–1155. DOI: 10.1123/ijspp.2019-0265 (2020).
No competing interests reported.