Sprint performance is critical in soccer, with most sprints following a curvilinear rather than a linear path. While isometric strength (IS) has been linked to linear sprint (LS) and change of direction (COD) performance, its relationship with curve sprint (CS) performance remains unclear. Hence, in this study, we analyzed the relationship between IS and CS performance in elite female soccer players. Nineteen elite female soccer players (age: 25.32 ± 4.18 years; body height: 167 ± 6.0 cm; body mass: 59.26 ± 5.34 kg; body fat percentage: 12.70 ± 2.18%) participated in a pre-season testing protocol. Following a standardized warm-up, players performed assessments of isometric hamstring strength (ISO), the isometric mid-thigh pull (IMTP), and CS performance. IS was measured using a portable force plate, which is the gold standard for such assessments. Pearson correlation analysis examined the relationship between IS variables and CS performance. No significant correlations were found between IS measures and CS performance (r = −0.198 to 0.296, p ≥ 0.05), indicating that IS tests may not accurately reflect force production during velocity-specific activities, such as the CS, in elite female soccer players. Further studies should examine other neuromuscular and biomechanical factors affecting CS performance.

This randomized parallel-group study examined the effects of curvilinear sprint (CS) training with different radii on linear sprint (LS) performance, CS ability, change of direction (COD), and horizontal force-velocity (FV) profile in youth soccer players. Eighteen male youth soccer players from the same academy were randomly assigned to a narrow CS group (NCSG; 5.15 m radius) or a wide CS group (WSCG; 11.15 m radius). Both groups completed 12 CS sessions over 6 weeks (2 sessions/week), integrated into their regular team training. Pre- and post-intervention assessments included LS (5-30 m), CS tests on both the good and weak sides over two radii (7.15 m and 9.15 m), modified 505 COD test, and sprint mechanical variables from the FV profile (F0, V0, Pmax, RFmax, Drf). No significant time × group interactions were found for any variable (p > 0.05), indicating that narrow and wide CS training produced similar adaptations. However, within-group analyses revealed significant improvements (p ≤ 0.05) in most CS tests (except for the good side on 9.15 m), in 5 m and 20 m LS times and COD performance. Additionally, the NCSG and WCSG showed small to moderate significant enhancements (p ≤ 0.05) in Pmax and RFmax after the training intervention. In conclusion, 6 weeks of CS training improved LS, CS ability, COD performance, and key sprint mechanical outputs in youth soccer players. These findings suggest that CS training is a specific and effective method for enhancing multidirectional speed and sprint mechanics in this population.

ABSTRACT:Herzog, S, Philippi, M, Feldmann, A, Asian, J, Filter, A, Requena, B, Batterson, PM, and Bogdanis, GC. Muscle oxygen saturation as a marker of internal load in elite soccer: A case series. J Strength Cond Res 40(9): e991-e998, 2026-Accurate monitoring of internal and external load during training is essential for optimizing performance and managing fatigue. In soccer, heart rate (HR) is commonly used to assess internal load. This study examined the use of muscle near-infrared spectroscopy, which measures muscle oxygen saturation (SmO 2 ), as a potential alternative to HR by providing real-time insights into local muscular effort. Seventeen elite male professional soccer players (21.2 ± 4.01 years) performed an incremental treadmill test to exhaustion, of whom 14 had complete data sets suitable for threshold analyses. During the test, HR, expired gases, and SmO 2 of the vastus lateralis were continuously measured to identify ventilatory, lactate, and SmO 2 breakpoints. On a separate day, HR and SmO 2 were recorded in a subset of five players during small- and large-sided games (SSG and LSG). A repeated-measures analyses of variance comparing HR corresponding to the three different thresholds indicated that HR at BP2 (178 ± 5 beats·minute -1 ) was similar with HR at LT2 and VT2 (177 ± 7 beats·minute -1 and 181 ± 6 p = 1.000 and p = 0.0920, respectively). Bland-Altman analysis indicated acceptable agreement between HR thresholds, while SmO 2 thresholds showed wider limits of agreement and greater individual variability. During small-sided game and LSG, players spent significantly more time above SmO 2 -based thresholds compared with HR-based thresholds ( p < 0.05), with the largest differences observed during LSG. These findings suggest that SmO 2 is more responsive to high-intensity, intermittent activity and may better reflect local muscular demand than HR. Incorporating SmO 2 into training and match monitoring may enhance internal load assessment and support more individualized performance and recovery strategies.

This study aimed to examine the curved and linear sprint performance scores of the U17 soccer team according to player positions. A total of 30 volunteer soccer players playing for Göztepe Football Club (GFK) U-17 team participated in the study. The average right side curved sprint weak side (RSCS-WS) performance time of the GFK U-17 team was found to be 2.65±0.10 s, the average left side curved sprint good side(LSCS-GS) performance time was 2.61±0.10 s and the average LS performance time was 2.65±0.06 s. The average performance times of GFK U-17 players according to their positions were as follows: RSCS-WS forwards 2.61±0.08 s, Stoppers 2.66±0.07 s, midfielders 2.64±0.12 s, fullbacks 2.59±0.10 s, wingers 2.69±0.07 s, and goalkeepers 2.74±0.13 s, and the total average value was determined to be 2.65±.10. The average sprint performance times measured by LSCS-GS for the curved were: forwards, 2.64±0.09 s; Stoppers, 2.59±0.07 s; midfielders, 2.62±0.13 s; fullbacks, 2.55±0.06 s; wingers, 2.61±0.05 s; goalkeepers, 2.67±0.11 s, and the total average value was determined to be 2.61±.09. LS performance times were determined as follows: forwards 2.64±0.06 s, stoppers 2.68±0.07 s, midfielders 2.64±0.06 s, fullbacks 2.64±0.05 s, wingers 2.63±0.05 s, goalkeepers 2.68±0.08 s, and the total average value was determined to be 2.65±.06. When examining the relationship between CS and LS performances, a high level of correlation was found between RSCS-WS and LSCS-GS (r: 0.737, p0.05). When examined according to the positions played by the participants, no statistically significant difference was found between the groups (p>.05).

ABSTRACT:Beato, M, Datson, N, Clemente, FM, Harper, DJ, Fílter, A, Emmonds, S, Dos' Santos, T, and Jones, PA. Linear and multidirectional speed testing (on-field and off-field) protocols in senior and elite female football. J Strength Cond Res 39(1): e70-e84, 2025-Female football has had a considerable rise in popularity with millions of fans after matches during the recent Women's World Cup. Despite this, the football scientific literature is still biased toward male footballers; therefore, this review aims to present the most recent literature and best practices for assessing linear and multidirectional speed and underpinning physical qualities, and to offer practical recommendations based on the most recent evidence and authors' expertise for practitioners working with female football players. This review categorizes tests as on-field and off-field, highlighting common protocols, their advantages, and the existing limitations. Among the most common on-field tests, we found the change of direction speed, horizontal deceleration, linear sprinting, and curved sprinting; although the suggested off-field tests are multi-joint isometric, single-joint isometric, isokinetic dynamometry, Nordic hamstring, and vertical jumps. These tests are valuable tools for assessing players' physical abilities, serving as a benchmark for tracking physical changes throughout the season, and aiding practitioners in individualizing and optimizing training protocols. This review highlights that strength (eccentric, isometric, concentric, and reactive) and rapid force production are crucial for generating braking and propulsive forces, which underpin linear and multidirectional motion. In conclusion, the evidence and practical suggestions reported in this review will improve the practitioners' knowledge of which tests and the consequent training protocols can be used in senior and elite female football players. But practitioners need to be aware about the scarcity of comprehensive studies on female soccer that hinders a complete understanding of the reliability of all assessment protocols used.

The purpose of this study was to examine the effects of linear sprint training (LST) compared to curvilinear sprint training (CST) using an equivalent session training volume, on linear (LS) and curvilinear (CS) sprint performance, horizontal force-velocity profile, and change of direction (COD) ability in young soccer players. In a randomized pre-post parallel-group trial design, nineteen U16 male soccer players were randomlyassigned to LST (n = 9) and CST (n = 10) groups. Both groups performed 11 sprint training sessions over 6 weeks. Before and after the training period, LS (5 m, 10 m, 15 m, 20 m, and 30 m), CS (weak and good side), horizontal force-velocity profile, and COD speed (modified 505 test) were assessed. The LST showed small to moderate significant enhancements (p <= 0.05) in LS (except 5 m sprint), modified 505 test, theoretical maximal velocity (V0), maximal power output (P-max), and maximal ratio of force (RFpeak) from pre -test to post -test. CST resulted in small to moderate significant improvements (p <= 0.05) in 10 m, 20 m, and 30 m LS performance,weak and good sides of the CS, COD speed, and P-max from pre -test to post -test. In addition, significant between-group comparisons were observed between LST and CST for CS performance in both sides (p < 0.01). In conclusion, LST and CST seem to produce trajectory-specific adaptations in young soccer players. Therefore, strength and conditioning coaches should integrate both LST and CST training methods to effectively prepare soccer players and enhance their sprinting performanc

Curved sprinting has been proposed as a relevant and specific skill for soccer players' physical performance. However, professional timing systems are not always readily available in less resource-constrained environments. To address this issue, the development of a low-cost and user-friendly smartphone application could have practical applications for team sports staffs. In this context, the objective of this study was to evaluate the validity and reliability of the My Jump Lab application for the measurement of the curved sprint performance test. Correlational, comparative, and Bland-Altman analyses were conducted to assess the validity and reliability of the application in comparison with the gold-standard device. The results demonstrated excellent concurrent validity (r = 0.97-0.99, p < 0.001), and acceptable reliability (coefficient of variation < 3%, intraclass correlation coefficient = 0.88-0.96). Bland-Altman plots revealed small biases (-0.015 s and -0.010 s for the 17-m and 8.5 m curved sprints, respectively) and narrow 95% limits of agreement (-0.04 to 0.01 s and -0.03 to 0.01 s), indicating string agreement and no heteroskedasticity. Although small but significant differences were observed between test and retest sessions (p < 0.05), the overall findings support that My Jump Lab is a valid and reliable tool for assessing completion time during the curved sprint test in the specified arc, offering a cost-effective alternative for applied sport settings.

The aims of this study were (i) to compare the sprint times between linear-sprint (LS) and curved-sprint (CS) tests of different radii, and (ii) to examine the relationships between sprint times in these tests in soccer players. Nineteen elite youth male soccer players (age, 18.6 ± 0.6 years) completed an LS test and three CS tests with different radii both from the left and the right side (11.15-m radius = CS wide , 9.15-m radius = CS medium and 7.15-m radius = CS narrow ), each with a distance of 17 m. Differences in sprint times were examined using analysis of variance with Bonferroni-corrected pairwise comparisons and Cohen's d effect sizes (ES). Relationships between sprint times were determined by Pearson's product-moment correlations (r). Significantly lower sprint times were evident for LS compared to all three CS tests ( p < .001, MD = 0.08–0.16 s, ES = 0.83–1.49), for CS wide compared to CS narrow ( p = .02, MD = 0.04 s, ES = 0.47) and for CS medium compared to CS narrow ( p < .001, MD = 0.07 s, ES = 0.82). Very large correlations ( p < .001, r = 0.75–0.80) were found between sprint times in LS and the three CS tests. Very large to nearly perfect correlations ( p < .001, r = 0.79–0.91) were found within the three CS tests. Practitioners should be aware that sprint times are lower in LS compared to CS of different radii and that CS times are higher at narrower angles compared to wider angles. Given the high correlations within three CS tests, the application of only one CS (e.g., CS medium ) during a test battery may be sufficient if using different CS is not possible. Results of the correlation analysis also suggest that LS contributes to CS performance, however, to slightly different extents depending on the radius of the CS. Consequently, both LS and CS drills might be incorporated into sprint training practices of elite youth soccer players.

Over the years, soccer has become more physically demanding; the number and frequency of high-intensity actions have increased, and these activities are decisive in determining the match outcome. Importantly, the reductionist approach commonly used to analyze high-intensity actions does not contemplate a more contextualized perspective on soccer performance. Traditionally, most investigations have only provided quantitative data regarding sprints (i. e. time, distances, frequency) without examining “how” (e. g. type of trajectory or starting position) and “why” (e. g. tactical role) soccer players sprint. In fact, other high-intensity actions, apart from running, are not even mentioned (i. e. curve sprints, change of direction, and specific-jump tasks). This has led to the use of tests and interventions that do not accurately reflect real game actions. Given the true technical-tactical-physical demands of each playing position, this narrative review collected a wide-spectrum of current soccer-related articles and provided a discussion regarding high-intensity actions, with a positional-based approach. In this narrative review, practitioners are encouraged to contemplate and consider the different elements that characterize high-intensity actions in soccer, in order to assess and train soccer players under a more sport-specific and integrative perspective.

The objective of the study was to evaluate the effectiveness of the Safe Landing (SL), a 6-week technique-modification (TM) programme, on cutting and jump-landing movement quality in football players. In a non-randomized design, 32 male semi-professional football players from two Spanish clubs participated in the study: one served as the control group (CG, n = 11), while the other performed the SL (n = 15). Performance and movement quality of drop vertical jump and 70º change of direction (COD70) were evaluated through 2D video footage pre- and post-intervention. In such tasks, the Landing Error Scoring System for first (LESS1) and second (LESS2) landings, and the Cutting Movement Assessment Score (CMAS) were used for assessing movement quality. Pre-to-post changes and baseline-adjusted ANCOVA were used. Medium-to-large differences between groups at post-test were shown in CMAS, LESS1 and LESS2 (p < 0.082, ղ2 = 0.137-0.272), with small-to-large improvements in SL (p < 0.046, ES=0.546-1.307), and CG remaining unchanged (p > 0.05) pre-to-post. In COD70 performance, large differences were found between groups (p < 0.047, ղ2 = 0.160-0.253), with SL maintaining performance (p > 0.05, ES=0.039-0.420), while CG moderately decreasing performance (p = 0.024, ES=0.753) pre-to-post. The SL is a feasible and effective TM program to improve movement quality and thus potential injury risk in cutting and landing, while not negatively affecting performance.

Research has shown that soccer players regularly execute curved sprints during matches. The purpose of this study was to determine the age-related effects on curve sprint (CS) performance to both sides, asymmetry, and association with linear sprint (LS). Eighty-four soccer players (aged 16.1 ± 1.6 categorized in U15, U17, and U20) were recruited, who performed CS and LS tests. One-way analysis of variance (ANOVA) and effect size (ES) were used to compare CS performance between age categories, and relationships between physical performance measures were calculated using Pearson's correlation coefficient. The main findings of this study were that: 1) there were significant differences in the "good" side CS among age groups (p < 0.001; ES from moderate to large), but not in the "weak" side CS, 2) curve asymmetry was significantly higher in U20 than U15 (p < 0.05; ES large) and U17 players (p < 0.05; ES moderate), and 3) relationships between CS and LS times decreased with age (from significant and very large [p < 0.001] to non-significant and smallmoderate [p > 0.05]). This study highlights the importance of assessing and training CS in different age categories, an action that becomes less correlated with LS as age increases, with the aim of mitigating the increase in asymmetries as a result of the specialization process, focusing interventions mainly on improving the CS "weak" side.

Objectives: To investigate the relationship between the Landing Error Scoring System (LESS) and Cutting Movement Assessment Score (CMAS) to evaluate movement quality, their intra-(INTRAob) and inter-observer (INTERob) reliability, and the comparison between the two drop vertical jump (DVJ) landings (1st and 2nd). Design: Cross-sectional. Participants: 42 male semi-professional soccer players performed three trials of DVJ and 70 degrees change of direction with a ball located as an external focus. Main outcome measures: Movement quality was evaluated through 2D video footage using the CMAS and LESS, screened by two observers. Relational, comparative and reliability analyses were conducted. Results: Both tools showed moderate to substantial (ICC = 0.58-0.71), and substantial to almost perfect (ICC = 0.68-0.87) INTRAob and INTERob reliability, respectively. No significant associations were found among CMAS, LESS 1st and 2nd for either scores or risk profiles (r = -0.158-0.202, p > 0.05). LESS 2nd was moderately higher (ES = 0.80-0.83, p = 0.002-0.0 07) than 1st scores. Conclusions: CMAS and LESS are reliable tools to evaluate movement quality, although evaluations should be preferably performed by the same observer; ACL injury risk profile's is task-dependent; both landings of the DVJ should be assessed as they represent different biomechanical and neuromuscular control deficits. (c) 2022 Elsevier Ltd. All rights reserved.

The aims of this study were (a) to assess intra-session reliability and usefulness of the soccer-specific maximum vertical jump (heading test, HT) and (b) to analyse the validity of the easy-to-use and cost-effective instrument (smartphone camera, MOB) compared with gold-standard instrument (3D motion capture system, MOCAP) to obtain the vertical jump performance during HT. Twelve semi-professional high-level and fifteen amateur soccer male players (23.9 ± 3.6 years) performed three HT attempts, and kinematic data were recorded with MOB and MOCAP. Intra-class correlation coefficient (ICC) and coefficient of variation (CV) were used as measures of intra-session reliability. T-test with Cohen's effect size (ES), Pearson's product moment and Bland-Altman analysis were used to obtain MOB validity. Regarding intra-session reliability, the CV was 1.13%, and ICC was 0.98, considered acceptable. Respecting validity criteria did not reveal significant differences (p < 0.05; effect size = 0.06, considered trivial), 'almost perfect' correlation (Pearson) (r = 0.98; p < 0.05), and strong agreement were obtained between MOB and MOCAP. This finding showed a test (HT) with a specific character, using cost-effective instrument and applicable to all soccer fields (adjusted to the standardised lines in the soccer field), all of them backed-up by reliability, usefulness and validity criteria.

Objective: In soccer, vertical jump means jumping toward a ball. Since no vertical jump test includes the ball as a reference element, the effect that the ball would have in a vertical jump test is unknown. The aim of this study was to examine the biomechanical differences between run-up vertical jump measurements without (Run-up Vertical Jump) and with ball inclusion (Heading Test). Methods: Twelve semi- and professional soccer players were recruited. Athletes performed both jump tests in a biomechanical laboratory, where kinetic and spatiotemporal variables were collected and compared using a Student's dependent t-test for paired samples. Results: Overall, players performed a different jumping strategy during the heading test compared to the run-up vertical jump, exhibiting: 1) higher horizontal velocity during initial contact (+45.3%, P <= .001), 2) shorter contact time, greater rate of force development, and total impulse during push-off (+27.5%, +53%, and +10.6%, respectively, P <= .008), 3) higher CoM horizontal and resultant velocity during take-off (+76.1% and 20.5%, respectively, P <= .001), 4) better vertical jump performance (+4.3%, P <= .0001), and 5) larger body angle rotation during landing (+63.3%, P = .006), compared to run-up vertical jump (effect size: 0.78 to 3.7). Conclusion: In general, soccer players display greater vertical jump heights in heading test, which highlights the importance of including an overhead ball during soccer-specific jump tests. Coaches and practitioners are encouraged to assess, and perhaps develop, the jumping ability of soccer players using a suspended ball as a specific target.

The aim of this study was to examine the associations between linear sprint, curve sprint (CS), change of direction (COD) speed, and jump performance in a sample of 17 professional female soccer players. All athletes performed squat and countermovement jumps, single leg horizontal triple jumps, 17 m linear sprints, CS tests, and a 17 m Zigzag COD test. A Pearson product–moment test was performed to determine the relationships among the assessed variables. The significance level was set at p < 0.05. Nearly perfect associations (r > 0.9) were found between linear and CS velocities. Players faster in linear sprints and CS exhibited greater COD deficits. No significant associations were found between COD deficit and either body mass or sprint momentum. Jumping ability was significantly correlated with linear sprint and CS performance, but not to COD performance. These findings may be used by coaches and practitioners to guide testing and training prescriptions in this population. The associations observed here suggest that training methods designed to improve linear sprint and CS velocities may benefit from the implementation of vertically and horizontally oriented plyometric exercises.

The incidence and recurrence of hamstrings injuries are very high in sports, posing elevated performance and financial-related costs. Attempts to identify the risk factors involved in predicting vulnerability to hamstrings injury is important for designing exercise-based programs that aim to mitigate the rate and severity of hamstrings injuries and improve rehabilitation strategies. However, research has shown that non-modifiable risk factors may play a greater role than modifiable risk factors. Recognizing non-modifiable risk factors and understanding their implications will afford the prescription of better suited exercise programs, i.e., that are more respectful of the individual characteristics. In a nutshell, non-modifiable risk factors can still be acted upon, even if indirectly. In this context, an underexplored topic is how intra and inter- individual anatomic and physiologic variations in hamstrings (e.g., muscle bellies, fiber types, tendon length, aponeurosis width, attachment sites, sex- and age-related differences) concur to alter hamstrings injuries risk. Some anatomic and physiologic variations may be modifiable through exercise interventions (e.g., cross-sectional area), while others may not (e.g., supernumerary muscle bellies). This apparent dichotomy may hide a greater complexity, i.e., there may be risk factors that are partially modifiable. Therefore, we explored the available information on the anatomic variations of the hamstrings, providing a deeper insight into the individual risk factors for hamstrings injuries and contributing with better knowledge and potential applications toward a more individualized exercise prescription.

Practitioners usually include change of direction (COD) and linear speed measurements in the testing batteries of soccer players; however, despite being a commonly occurring action, curve sprint (CS) ability is rarely assessed in soccer. The aims of this study were to analyze the association between linear sprint, CS, and COD speed performances, and compare the association and direction of asymmetries between these skills. Thirty-three male soccer players performed linear sprint (17 m), CS (17 m), and COD-90⍛ speed tests (COD [8.5 + 8.5 m]). Our main findings were (a) a large relationship between linear and multidirectional tasks (COD-90⍛ and CS tests) (r = from 0.6 to 0.64, p < 0.05), (b) a moderate relationship between CS and COD-90⍛ tests (r = from 0.33 to 0.41, p < 0.05), with a certain opposite tendency (higher relationships between opposing directions [CurveLEFT - CODRIGHT; r = 0.41] than between equal directions [CurveLEFT – CODLEFT; r = 0.33]), and (c) no relationship (p > 0.05) between COD and CS asymmetries, with opposing directional dominance in ~70% of players (e.g., curve left and COD right dominance). These results indicate that performance in linear sprints is strongly related to performance in multidirectional trajectories, whereas CS and COD-90⍛ seem to be more independent actions. Additionally, the direction of asymmetry or dominance is generally opposite between the non-linear tasks measured.

Anterior cruciate ligament (ACL) is one of the most concerning injuries for football players. The aim of this review is to investigate the effects of exercise-based interventions targeting at reducing ACL injury rate or mitigating risk factors of ACL injury in adult football players. Following PRISMA guidelines, a systematic search was conducted in CINAHL, Cochrane Library, PubMed, Scopus, SPORTDiscus and Web of Science. Studies assessing the effect of exercise-based interventions in ACL injury incidence or modifiable risk factors in adult football players were included. 29 studies evaluating 4502 male and 1589 female players were included (15 RCT, 8 NRCT, 6 single-arm): 14 included warm-up, 7 resistance training, 4 mixed training, 3 balance, 1 core stability and 1 technique modification interventions. 6 out of 29 studies investigated the effect of interventions on ACL injury incidence, while the remaining 23 investigated their effect on risk factors. Only 21% and 13% studies evaluating risk of injury variables reported reliability measures and/or smallest worthwhile change data. Warm-up, core stability, balance and technique modification appear effective and feasible interventions to be included in football teams. However, the use of more ecologically valid tests and individually tailored interventions targeting specific ACL injury mechanisms are required.

We examined the relationships among linear speed, vertical jumping ability and curve sprint (CS) performance. Moreover, the correlations between linear and curvilinear sprint velocities and CS deficit were tested. Twenty-eight under-20 soccer players performed squat and countermovement jumps, 17-m linear sprint (with split times at 5 and 10 m), and a CS test for both sides. For the first time, the new proposed CS deficit was calculated as the difference between 17-m velocity and CS test velocity. Pearson's product moment of correlation was performed to determine the relationships among the distinct variables tested. Significance level was set at P < 0.05. Large to very large relationships between linear sprint speed and CS performance were observed, on both the "good" and "weak" sides. In addition, moderate to large correlations between linear and curve sprint abilities and vertical jumps were found. Finally, the CS deficit was negatively associated with the CS good side performance. Linear sprint and CS velocities for both good and weak sides were closely related. The CS deficit was only related to the CS weak side performance, and the vertical jumping ability was significantly associated with both linear and curvilinear sprint velocities. The present results suggest that training methods capable of improving linear sprint and vertical jumping abilities may also improve CS performance.

Sprinting in curvilinear trajectories is an important soccer ability, corresponding to ~85% of the actions performed at maximum velocity in a soccer league. We compared the neuromuscular behavior and foot contact-time between outside leg and inside leg during curve sprinting to both sides in soccer players. Nine soccer players (age=23±4.12 years) performed: 3×Sprint linear, 3×Sprint right curve, and 3×Sprint left curve. An ANOVA with repeated measures was used to compare the differences between inside and outside leg, and Cohen's d was used to calculate the effect-size. Considering the average data, the performance classification (from best to worst) was as follows: 1. Curve "good" side (2.45±0.11 s), 2. Linear (2.47±0.13 s), and 3. Curve "weak" side (2.56±0.17 s). Comparing linear with curve sprinting, inside leg recorded significant differences ("good" and "weak"; effect size=1.20 and 2, respectively); in contrast, for outside leg, there were no significant differences ("good" and "weak"; effect size=0.30 and 0.49, respectively). Electromyography activity showed significant differences (p≤0.05) during curve sprinting between outside (higher in biceps femoris and gluteus medius) and inside leg (higher activity in semitendinosus and adductor). In summary, inside and outside leg play different roles during curved sprints, but inside leg is more affected by the change from straight to curve sprint.