نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری آسیب شناسی ورزشی و حرکات اصلاحی، دانشکده علوم ورزشی، دانشگاه اصفهان، اصفهان، ایران
2 استاد گروه آسیب شناسی ورزشی و حرکات اصلاحی، دانشکده علوم ورزشی، دانشگاه اصفهان، اصفهان، ایران
3 دانشیار گروه آسیب شناسی ورزشی و حرکات اصلاحی، دانشکده علوم ورزشی، دانشگاه اصفهان، اصفهان، ایران
کلیدواژه‌ها
موضوعات
عنوان مقاله English
نویسندگان English
Background and Purpose
Soccer, a high-intensity sport, involves unilateral actions such as jumping and change of direction speed (CODS) (1). These motor skills are interconnected and essential for achieving successful performance, impacting match outcomes (2). Strength (jumping) and CODS are crucial components of this sport, and the ambition of teams to achieve top rankings has escalated the likelihood of injuries (3). The most common soccer injury is a lateral ankle sprain, often caused by a combination of inversion and plantarflexion during functional movements of soccer like CODS and jumps (4). Chronic ankle instability (CAI) is a common outcome of these sprains, with approximately 32% to 74% of individuals experiencing ongoing problems despite common treatments (5). Research has shown that CAI can lead to increased asymmetry in the lower limbs, increasing the athlete's risk of injury. Therefore, this study aimed to assess functional strength asymmetry and CODS in soccer players with CAI.
Materials and Methods
A cross-sectional design assessed inter-limb strength asymmetry and CODS in elite soccer players with CAI. Initially, a minimum sample size of 19 participants was calculated using G*Power software based on a squared multiple correlation of 0.36, power of 0.8, and significance level <0.05 (6). However, thirty-two male elite soccer players with unilateral CAI (age=21.78±3.18 years; height=177.28±6.87 cm; mass=68.39±8.82 kg) participated, meeting inclusion criteria based on International Ankle Consortium recommendations. Tests were conducted barefoot on an indoor track. Each athlete performed three trials for each limb in all CODS and strength tests, with the average of these trials used for analysis. The dominant limb was the preferred kicking limb. Horizontal strength asymmetry was evaluated using the Single-leg Hop (SLH) and Triple Hop (SLTH) tests, while CODS asymmetry was assessed through the 180° turn and 90°Cut tests for both injured/uninjured and dominant/non-dominant limbs (6). Inter-limb asymmetries were quantified using the formula: 100/uninjured (and D) limb × injured (and ND) limb × -1 + 100, as recommended for unilateral tests (1). Asymmetry thresholds were determined for strength tests using the formula (mean of asymmetry + (0.2 × SD)) and for CODS tests using the formula (mean of asymmetry - (0.2 × SD)). The similar identification of asymmetry was calculated as (frequency of similar identification / number of athletes) × 100, with agreements ≥80% considered good. Within-session reliability was calculated using intraclass correlation coefficients (ICC) and coefficient of variation (CV), with minimum acceptable reliability set at ICC > 0.7 and CV < 10 (6). Paired t-tests were used to compare differences between limbs, while effect sizes were calculated using Hedges' g method and interpreted based on the Hopkins scale. The relationship between inter-limb strength asymmetry and CODS performance was calculated using Pearson's correlation coefficient and interpreted according to the Hopkins scale.
Findings
Acceptable reliability and levels of variation were observed for the injured and uninjured limbs in all variables. The mean and SD of CAIT scores for the injured and uninjured limbs were 17.47 ± 2.02 and 28.94 ± 1.08, respectively. Out of the total 32 players, 25 (78%) had CAI in their dominant limbs, while 7 (22%) experienced CAI in their non-dominant limbs. A significant difference was noted between the dominant and non-dominant limbs (p<0.05) as well as between the injured and uninjured limbs (p<0.05) in all tests. However, a more significant directional defect was observed between the injured and uninjured limbs (g SLH = 1.60, g SLTH = 1.10, g Mod505 = -1.97, g 90°Cut = -1.40) compared to the dominant and non-dominant limbs (g SLH = 0.59, g SLTH = 0.58, g Mod505 = -0.90, g 90°Cut = -0.74) (Table 1). A significant correlation was observed between inter-limb (injured/uninjured) asymmetry in the SLH test and Mod505 of the non-dominant limb (r=0.392), Mod505 of the injured limb (r=0.413), and inter-limb (injured/uninjured) asymmetry of Mod505 (r=-0.452). Additionally, a significant correlation was found between inter-limb (injured/uninjured) asymmetry in the SLTH test and 90°Cut of the dominant limb (r=0.362) and 90°Cut of the injured limb (r=0.373). Low levels of agreement were observed in the similar identification of inter-limb asymmetry between Hop and CODS tests (15.63–25%). Additionally, a weak level of agreement was observed in the similar identification of inter-limb asymmetry between Mod505 and 90°Cut (12.5%). The thresholds of asymmetry in Mod505 and 90°Cut were -11.90 and -10.23, respectively (Table 1), and 12 players showed asymmetry greater than these thresholds in both tests. In the SLH test, the asymmetry threshold was 9.68, and 15 players had asymmetry beyond this threshold, of which 8 players showed asymmetry in the Mod505 test and 5 players showed asymmetry in the 90°Cut test. In the SLTH test, the asymmetry threshold was 7.73, and 12 players had asymmetry beyond that, of which 5 players showed asymmetry in the Mod505 test and 5 players showed asymmetry in the 90°Cut test.
Conclusion
Studies have indicated that turning, cutting, and jumping are common traumatic actions in CAI, leading to increased inter-limb asymmetry (1–4). However, functional strength asymmetry and CODS in elite soccer players with CAI have not been thoroughly analyzed. This study introduced specific asymmetry thresholds for horizontal functional strength and CODS in elite soccer players with CAI. Furthermore, the study highlighted that the dominant limb, crucial for performing soccer skills, sustains significantly more injuries. This can notably impair the performance of soccer players with CAI during functional soccer activities such as turning, cutting, and jumping. While correlations were observed between inter-limb strength asymmetry and CODS, there were low levels of agreement in similar identification of inter-limb asymmetry across tests. This discrepancy highlights that asymmetries are task-specific. Therefore, preparation and rehabilitation programs must include tests that assess these skills to avoid bias in result interpretation and identify deficits in movement patterns.
Article Message
This study can enhance understanding and awareness of inter-limb strength asymmetry and change of direction speed and their mutual effect on elite soccer players with CAI. The findings from this study can also prove effective in optimizing CAI preparation and rehabilitation programs.
کلیدواژه‌ها English
