Change-of-Direction Ability of Para-Footballers With Cerebral Palsy Under a New Evidence-Based and Sport-Specific Classification System

Sex differences in change of direction deficit and asymmetries in footballers with cerebral palsy

The aims of this study were (1) to describe and examine differences in change of direction (COD) performance and the magnitude of asymmetries in para-footballers with cerebral palsy (CP) and controls and (2) to evaluate the association between COD outcomes and linear sprint performance. Twenty-eight international para-footballers with CP and thirty-nine non-impaired football players (control group) participated in this study. All participants completed a 10-m sprint and two attempts of the 505 COD test with the dominant and non-dominant leg. The COD deficit was calculated using the difference between the 505 test and the 10-m sprint time, while the asymmetry index was determined by comparing each leg's completion time and COD deficit. Players across groups showed interlimb asymmetries between the dominant and non-dominant legs in COD outcomes and deficit (p < 0.05, d_g  = -0.40 to -1.46), although these asymmetries imbalance were not significantly different between the sexes with and without impairment. Males with CP exhibited a faster directional COD speed and a shorter COD deficit than their female counterparts (p < 0.01, d_g  = -1.68 to -2.53). Similarly, the control group had faster scores than the CP groups of the same sex (p < 0.05, d_g  = 0.53 to 3.78). Lastly, the female CP group and male control groups showed a significant association between sprint and the COD deficit in the dominant leg (p < 0.05, r = -0.58 to 0.65). Therefore, the use of directional dominance, the COD deficit, and asymmetry outcomes could be helpful for classification purposes to assess the impact of the impairment on sport-specific activity testing according to sex.

Differences in kinetic characteristics during countermovement jump of football players with cerebral palsy according to impairment profiles

Objectives: The purpose of this study was 1) to determine and compare kinetic parameters during the realization of a countermovement jump (CMJ) between footballers with cerebral palsy (CP) and non-impaired footballers, and 2) to analyze the differences in this action between different players' impairment profiles and a group of non-impaired footballers. Methods: This study involved 154 participants comprising 121 male footballers with CP from 11 national teams and 33 male non-impaired football players recruited as the control group (CG). The footballers with CP were described according to the different impairment profiles (bilateral spasticity = 10; athetosis or ataxia = 16; unilateral spasticity = 77; minimum impairment = 18). All participants performed three CMJs on a force platform to record kinetic parameters during the test. Results: The group of para-footballers presented significantly lower values than the CG in the jump height (p < 0.01, d = -1.28), peak power (p < 0.01, d = -0.84), and the net concentric impulse (p < 0.01, d = -0.86). Concerning the pairwise comparisons between CP profiles and the CG, significant differences were found for the bilateral spasticity, athetosis or ataxia, and unilateral spasticity subgroups compared to the non-impaired players for jump height (p < 0.01; d = -1.31 to -2.61), power output (p < 0.05; d = -0.77 to -1.66), and concentric impulse of the CMJ (p < 0.01; d = -0.86 to -1.97). When comparing the minimum impairment subgroup with the CG, only significant differences were found for jump height (p = 0.036; d = -0.82). Footballers with minimum impairment presented higher jumping height (p = 0.002; d = -1.32) and concentric impulse (p = 0.029; d = -1.08) compared to those with bilateral spasticity. Also, the unilateral spasticity subgroup reports a higher jump height performance than the bilateral group (p = 0.012; d = -1.12). Conclusion: These results suggest that the variables related to power production during the concentric phase of the jump are crucial for the performance differences between groups with and without impairment. This study provides a more comprehensive understanding of kinetic variables that would differentiate CP and non-impaired footballers. However, more studies are necessary to clarify which parameters better differentiate among different profiles of CP. The findings could help to prescribe effective physical training programs and support the classifier's decision-making for class allocation in this para-sport.

Contextual Factors and Match-Physical Performance of International-Level Footballers with Cerebral Palsy

This study aimed to explore the match-physical response of international-level footballers with cerebral palsy (CP) according to contextual factors such as team ranking, the quality level of opposition, and match outcome. Eighty-two male outfield footballers with CP from top-ranked teams (n=26) and bottom-ranked teams (n=56) took part in this study. The match-player response was recorded using global position devices considering the total distance, distance covered at different velocities, and number of short-term actions. Players from top-ranked teams covered more distance at low intensities compared to players from bottom-ranked teams (p<0.05;0.45<ES<0.49). Higher sprint distance, moderate deceleration, and high accelerations/decelerations were found in players from top-ranked teams playing against teams of similar levels (p<0.05; 0.73<d_g<0.86). When players from bottom-ranked teams played against teams of equivalent rank, more physical requirements were presented in total distance, running from medium to sprint intensities, and the number of short-term actions (p<0.05;-0.55<ES<-0.89). Players from the top-ranking teams presented greater sprint distance and moderate acceleration demands in losing matches (p<0.05;-1.01<d_g<-1.03). Considering the bottom-ranking opposition, players presented more running demands in matches with losing results in moderate running, sprinting, and moderate-to-high deceleration (p<0.05;-0.61<d_g<-0.64). The match-physical response of players with CP varies according to the contextual factors studied. The results provide advice for coaches and classifiers to understand more comprehensively the competing demands in CP football. This knowledge could help practitioners to prepare competition matches and planning training load or post-match recovery strategies, but also for the observation assessments of the classification process in this team para-sport.

Analysis of scored goals in the cerebral palsy football World Cup

This study aimed to report the goal patterns in cerebral palsy (CP) football for a better understanding of the performance of this para-sport. All goals (270) of the 48 2019 IFCPF World Cup matches were analysed through match reports, and 65% of them were analysed by video footage. The results showed 5.6 goals per match. Teams that scored more and conceded fewer goals correlated to a better ranking position in the championship (r= 0.72-0.73; p< 0.01). The distribution of goals scored was not biased by halves (49.3% vs 50.7%; χ²= 0.1; p= 0.88) nor by 15-min periods (26.3% vs 23.0% vs 23.3% vs 27.4%; χ²= 0.5; p= 0.92). In 91.7% of the matches, the team which scored the first goal went on to win the match (χ²= 81.5; p< 0.01). FT3 players scored more goals by player (χ²= 22.1; p< 0.01), while there were no statistical differences in the distribution of goals conceded by goalkeepers according to their sport class (χ²= 4.7; p= 0.09). The goals were scored mainly from organized attacks (74.4%), from the penalty area (52.5%) and through individual action (51.9%). All this information could be crucial for coaches in CP football to plan their game strategies.

Comparison of the Physical Response During Official Matches and Small-Sided Games in International Cerebral Palsy Footballers: Implications for Evidence-Based Classification

This study aimed to analyze whether there are differences and associations in the physical responses in international-level cerebral palsy footballers between official matches and 2v2 small-sided games (2v2-SSG). One hundred seventy international cerebral palsy footballers participated in this study during three international championships. The physical responses of mean and maximum velocities, total distance, distance covered at different intensities, short-term actions, and player load were collected during 2v2-SSG and the real competition. The mean velocity, total distance, jogging, medium- and high-intensity distances, the number of moderate/high accelerations, decelerations, and player load were relatively higher in the 2v2-SSG than in the official matches. Even though the 2v2-SSG could become an appropriate drill to include during the classification process, due to the differences between a 2v2-SSG and the official competition, it is necessary to deepen the scientific knowledge for developing observation methods during real competition to strengthen the relationships between eligible impairments and activity limitation.

Changes in Sprint Force-Velocity Profile in International Para Footballers

PURPOSE

Force production is crucial in football, and it is the main limitation of people with cerebral palsy (CP). This study aimed to describe the changes in sprint force-velocity (Fv) profile after a period of 25 weeks of regular training in international football players with CP.

METHODS

The sprint Fv profile and other physical performance variables (ie, linear sprint, vertical jump, change of direction, and intermittent endurance) of 14 international players from the Spanish national team were assessed during 2 consecutive training camps. Pretesting and posttesting sessions were carried out 1 week before and after the 25-week intervention period. The intervention consisted of 2 strength sessions per week added to the usual football training.

RESULTS

The repeated-measures analysis of variance showed changes in players' physical performance (linear sprint: F = 18.05, P < .01; change of direction: F = 16.71, P < .01; and endurance: F = 31.45, P < .01) and in some variables of the sprint Fv profile (maximal horizontal force, maximal power, slope, maximal ratio of force, and decrease of ratio of force; F = 14.28-37.81; P < .01), whereas players' maximal velocity (theoretical and actual) did not change (F = 0.13 and 0.01; P = .72 and .98, respectively).

CONCLUSIONS

This study showed that the implementation of 2 strength-training sessions per week, for 25 weeks, is effective to improve CP football players' physical performance. The main finding of this study is the improvement of force application in the acceleration phase (sprint Fv profile), which is the main attribute in many physical performance tests and is the main limitation of the CP population.

Assessing the Sprint Force-Velocity Profile in International Football Players with Cerebral Palsy: Validity, Reliability and Sport Class’ Profiles

This study assessed and described the Sprint Force-velocity (SFv) profile, and its validity and reliability in international cerebral palsy (CP) football players. Twenty international male CP football players (age: 26.9±7.4) performed a 30-m sprint, a vertical jump (CMJ), a change of direction (MAT), a dribbling and an intermittent endurance (Yo-YoIR1) test. The SFv profile and physical performance variables were shown according to the players’ sport class with the estimation of the effect sizes between classes. The SFv showed high reliability (ICC=0.77 to 0.99; SEM=0.89 to 8.66%). Validity for the SFv was provided by its positive correlation with the players’ sport class (r=0.53 to 0.75; p=.02 to <.01) and the rest of the physical performance tests (r=0.45 to 0.99; p=.04 to <.01). The RFmax was the main SFv profile variable that explained players’ performance in the rest of the tests (β=0.77 to 1.0; p<.05; R2=0.59 to 0.99). The SFv profile seems to be an efficient test to assess international CP football players’ physical performance. This provides information about the players’ individual sprint mechanical characteristics and their sprint strengths and weaknesses, allowing coaches and conditioning trainers to individualize their training interventions to optimize sprint performance.

International football players with cerebral palsy maintained their physical fitness after a self-training program during the COVID-19 lockdown

Background

The COVID-19 global pandemic caused a complete stop in sport participation which meant a detraining period for athletes. High-level athletes had to train at home guided by their coaches and conditioning trainers in an effort to maintain their physical fitness. The aim of maintaining the training adaptations and physical fitness during the COVID-19 mandatory lockdown was especially important for CP athletes, in which the detraining period was expected to cause early declines in motor function, poor coordination and muscle weakness due to their disability.

Methods

The present study assessed the effect of a guided self-training program on international CP football players' physical fitness during the COVID-19 mandatory lockdown. Fifteen CP football players from the Spanish National Team participated in the study. An experimental design with a pre- (T1) and a post-intervention (T2) assessment was carried out, with a 12-week period of players' self-training (divided in two periods of 6 weeks) which combined strength and endurance training. Physical performance assessment consisted in the free countermovement jump (CMJ), 5, 10 and 20-m sprint, the modified agility T-test (MAT) and a dribbling test. The Kruskal-Wallis test was used for between-group comparisons, while the Student's paired t test or the Fisher Pitman permutation test, based on the normality of the data, were used for within-group comparisons.

Results

The results showed no differences between sport classes (FT1, FT2 and FT3) in physical fitness change after the training program (Chi² = 0.16 to 1.73; p = 0.42 to 0.92). Within-group comparisons showed an increase of jump height in the CMJ (4.19 cm [2.46, 5.93]; p < 0.001) and a maintenance of the 5, 10 and 20-m sprint, MAT and dribbling ability (<0.01 to 0.09 s; p = 0.19 to 0.97).

Discussion

To the authors' knowledge, this is the first study that examined the physical fitness adaptations to a training program with CP football players. The results show that a 12-week guided self-training program without football-specific stimulus may be effective to maintain or even improve the specific physical performance of international CP football players during a non-competitive period (as the COVID-19 lockdown). This study reveals that CP football players are able to show adaptations to the strength and endurance training and this could be the basis for future research regarding training adaptations in CP football players.

To What Degree Does Limb Spasticity Affect Motor Performance in Para-Footballers With Cerebral Palsy?

Spasticity is considered a contributor to hypertonia, frequently presented in people with cerebral palsy (CP), affecting muscle function and motor activities. In CP football, the classification system determines that this impairment is eligible for competitive para-sports due to the impact on activity limitation and sports performance. However, the relationship between this feature (i.e., spastic hypertonia) and performance determinants has not been explored yet. This study aimed to assess the association of clinical spasticity measurements with the performance of sport-specific tests used for classification purposes. Sixty-nine international footballers with CP voluntarily participated in this study. The Australian Spasticity Assessment Scale was used to measure spasticity in lower limbs muscle groups and activity limitation tests were conducted considering dynamic balance, coordination, vertical and horizontal jumps, acceleration, and change of direction ability. Low-to-moderate negative significant associations were found between the hip spasticity and measures of dynamic balance and dominant unipedal horizontal jump capacity. Additionally, moderate associations were reported between the knee spasticity and the non-dominant unipedal horizontal jump capacity and the change of direction actions with the ball. The ankle spasticity score reported small to moderate associations with the change of direction assessment without the ball and bipedal and dominant unipedal horizontal jump capability. Finally, the total spasticity score only presented a significant association with horizontal jump performance. This is a novel study that provides evidence of the associations between an eligible neural impairment and relevant specific measures of activity limitation tests. These results suggest that the amount of spasticity according to each evaluated joint muscle group of the lower limbs presents a low-to-moderate significant relationship with determined measures of dynamic balance, coordination, horizontal jump, acceleration, and change of direction ability with and without the ball in international-level CP footballers. Further studies are necessary to elucidate the real contribution of neural and non-neural impairments related to hypertonia on fundamental sport-specific motor skills of para-footballers with CP.