The literature search was conducted across different databases: the multidisciplinary Web of Science and Scopus; the biomedical and life sciences database PubMed; and the sport-dedicated database SPORTDiscus. Additional articles not indexed in these databases were provided by experts in the field. Grey literature sources were identified by searching titles through Google Scholar and the ITF Coaching & Sport Science Review journal, the official journal of the ITF. References from relevant articles were also reviewed to identify additional studies using the snowballing method (Naderifar et al., 2017).

The systematic search included all publications up to August 2024 to ensure a comprehensive identification of sources related to the topic. The following search terms and operators were applied across all databases in title-abstract-keywords parameters: (tennis NOT table NOT elbow) AND (scal* OR adapt* OR modif* OR mini*). These terms were selected after expert consultation. All database searches were performed by a single researcher to maintain consistency in the process.

The criteria for article selection were established by the researchers following the PECOS framework (Higgins et al., 2019), as detailed in Tables 1, 2.

The focus of the review was on novice tennis players, so it was a priority to include young tennis players between the ages of 6 and 14 as participants. However, it was also considered important to include other participants without prior experience, such as beginner adult players or players with disabilities.

Regarding the exposure criteria, studies with a cross-sectional design (data collection lasting between 1 and 5 days) were included. These studies involved participants with no prior training under adapted conditions and only observed differences between different conditions. Studies involving an intervention (either short-term or long-term) were also considered, corresponding to a training period with adaptations. Long-term exposure was defined as a training duration of 5 weeks or more since the longest intervention observed lasted 8 months.

To be included in the review, the research had to relate to scaled or adapted equipment in the sport of tennis, specifically focusing on intervention-based or empirical studies. Eligible studies were required to include a data collection or measurement process, accompanied by data analysis—whether qualitative, quantitative, or mixed methods—concerning the use of adapted equipment in tennis training, match performance, coaches’ perspectives, or other relevant variables. In addition, this review was restricted to manuscripts written in Spanish or English due to the linguistic capabilities of the researchers and because these were the predominant languages in the literature. Consequently, narrative documents, reviews synthesizing articles already included in the study, and publications in languages other than Spanish or English were excluded.

Titles and abstracts were sequentially evaluated, and those unrelated to the main topic were discarded. After removing duplicates, the full text of the remaining publications was reviewed to ensure compliance with the inclusion criteria. If the exclusion criteria, listed in Table 2, were identified during the full-text reading, the article was excluded. All titles and abstracts were independently reviewed by two researchers. To ensure a rigorous process, only articles deemed eligible by both reviewers were included based on the inclusion criteria. In cases of discrepancies, discussions were held until consensus was reached. This procedure aimed to minimize bias in the study selection process. For the systematic reviews identified in the process, the number of studies potentially meeting the inclusion criteria was noted, particularly if those studies had been overlooked during the initial search.

The quality of the articles included in the study was assessed using an adapted version of the Downs and Black (1998) checklist. Each article was evaluated on the following aspects: study purpose, background literature, study design, sample characteristics, statistical significance, data analysis methods, results, conclusions, and implications for future research (see footnote in Table 3). Each criterion was scored as follows: “+” if fulfilled, “–” if not fulfilled, and “NR” if the information was not reported. The scores were summed to obtain a total score, categorized as follows: less than 5 indicated low quality, between 5 and 7 indicated good quality, and 8 or more indicated high quality (van der Fels et al., 2015). The aim of this assessment was to identify and exclude any low-quality studies from the review.

After the initial classification of the sources, a matrix was developed to extract the most relevant data from the included articles. The matrix captured the following:

Using this information, the studies were categorized into the following emerging research lines:

Of a total of 6,900 articles identified, after the refinement procedure and application of the exclusion criteria, the final sample consisted of 35 studies. The selection and screening processes of the studies finally included in the review, according to the PRISMA procedure, are graphically presented in Figure 1.

Table 3 shows the quality scores for each article included in the scoping review, following the Downs and Black (1998) checklist. A total of 74% of the studies received high-quality ratings, and all exceeded the score of 5, at which the articles were considered to have good quality.

The main characteristics of each study included in this scoping review are summarized in Table 4. The full matrix detailing the characteristics of each study can be found in the Supplementary materials.

The analysis of all the articles identified different strands of research, into which they were classified, as reflected in Table 5. Although some articles addressed more than one topic and were included in multiple categories, this table provides a global overview of the research on adapted material in tennis, according to the themes identified.

A prominent and frequently addressed topic in the literature on modifying tennis equipment is its impact on the learning process of tennis skills, particularly in the development of technical abilities.

Most of the studies have focused on training methodologies and their role in skill acquisition. The key variables analyzed included stroke technique and performance (Farrow and Reid, 2010; Buszard et al., 2014b; Hammond and Smith, 2006; Buszard et al., 2014a; La, 2017; Fitzpatrick et al., 2018; Kilit et al., 2023). These studies typically examined the phases of the stroke—such as positioning, backswing, impact, and follow-through—comparing performance with scaled and standard equipment. Stroke performance is assessed through variables such as stroke volume, opportunities, and success rates. Buszard et al. (2014b) reported greater technical losses and disruptions with standard equipment compared to scaled equipment. Other studies employed specific skill tests, such as the TSST, as seen in studies by Fitzpatrick et al. (2018) and Kilit et al. (2023).

Notably, research on groundstrokes has shown significant improvements in speed, accuracy, and the relationships between speed, accuracy, and success when using scaled equipment. These adaptations have led to better forehand and backhand performances, with greater precision and power (Larson and Guggenheimer, 2013; Prodan and Grosu, 2017; Buszard et al., 2020b). A significant finding was the reduction in ball speed when using low-compression balls (Larson and Guggenheimer, 2013; Prodan and Grosu, 2017). The slower balls provide players with more time for preparation and positioning, resulting in greater technical efficiency and stroke success.

Studies have also explored broader adaptations, such as comparing mini-tennis to adult tennis, in terms of their effects on basic motor skills. Improvements were observed in hand-eye coordination (Hardoy et al., 2011), agility, and speed (Ciuntea, 2018), as well as in tennis-specific skills such as positioning, stroke technique, and court movement (Coldwells and Hare, 1994; Buszard et al., 2016b). These studies have consistently reported significant improvements and demonstrated that mini-tennis provides a positive transfer to adult gameplay.

In terms of age groups, research in this area has predominantly focused on children aged 6 to 9 years, as scaled adaptations are typically recommended for these age groups. However, more recent studies, such as Kilit et al. (2023), have included beginner adults, demonstrating that the benefits of scaled adaptations are not limited to children. These findings highlight the need for further exploration of the effects of scaled equipment on other populations, including adolescents, older adults, and individuals with functional diversity.

Another extensively studied area concerns the impact of equipment modifications in competitive contexts, with a focus on match performance. Research in this domain has often analyzed real or simulated matches, investigating technical-tactical variables and playing styles.

Several studies have examined the effects of equipment modifications on game structure, including point duration and effective playing time. Low-compression balls and reduced court dimensions were found to significantly increase point duration compared to traditional equipment (Sánchez-Alcaraz, 2013; Bayer et al., 2017; Fitzpatrick et al., 2017, 2018; Kilit et al., 2024). These modifications give players more time to react, position themselves, and execute strokes, resulting in longer rallies and more dynamic gameplay. Longer point durations also increase effective playing time, offering more opportunities to practice skills and engage in realistic match scenarios.

Other studies have focused on technical-tactical variables, particularly serve and groundstroke performance. Modifications such as reduced net height and smaller court dimensions have been associated with greater first-serve effectiveness and improved serve placement (Limpens et al., 2018; Bayer et al., 2017; Schmidhofer et al., 2014; Gimenez-Egido et al., 2020a; Gimenez-Egido et al., 2020b; Gimenez-Egido et al., 2023). For groundstrokes, scaled adaptations promote greater symmetry in the use of the forehand and backhand (Fitzpatrick et al., 2018; Fitzpatrick et al., 2017), addressing the common tendency of young players to favor the forehand over the backhand (Farrow and Reid, 2010) and aligning their play more closely with adult tennis.

Reducing net height has been shown to facilitate a more offensive playing style, increasing the frequency of flat, winning shots and net approaches (Giménez-Egido et al., 2020c). In addition, Kachel et al. (2015) reported that green balls resulted in more frequent net play and higher ball speeds. These findings suggest that scaled adaptations facilitate a playing style that mirrors adult tennis, providing players with more opportunities for tactical development.

Despite the consistent focus on technical-tactical variables in competitive scenarios, the studies reviewed varied in methodology, participant age and skill levels, and the specific adaptations implemented. Most studies explored modifications to court size and net height, while others examined balls with varying compression. Further research is needed to investigate the long-term effects of scaled equipment, the transition to standard equipment, and the customization of materials to player characteristics.

Studies examining biomechanical variables associated with scaled tennis equipment have focused on aspects of motor control and performance. Research by Buszard et al. (2020c) and Buszard et al. (2020b) highlighted improvements in stroke precision and distal arm segment control with scaled equipment. These studies observed increased temporal stability and reduced movement variability, along with better coordination between the upper arm and forearm. Methodological differences between the studies included analyses of racket-shoulder distance in relation to task success, control, and impact point in one study and variability in arm segment coordination and flexibility in the other.

Broadbent et al. (2021) expanded the biomechanical focus to include other sports, such as rugby, netball, basketball, and hockey, evaluating the relationship between athletes’ body measurements and sport-specific adaptations. The study noted that adaptations were more acceptable in female competitions than in male ones and that younger athletes (under 9 years old) faced greater challenges with oversized courts and equipment.

In serving, significant improvements in kinematic and kinetic variables were reported (Fadier et al., 2023; Touzard et al., 2023). Fadier et al. (2023) found that reduced court and net dimensions led to higher racket and ball speeds, increased knee extension velocity, and improved trunk flexion in young players. Touzard et al. (2023), while not observing significant differences in racket and ball speeds, reported increased angular velocities in distal arm segments and reduced loads on the shoulder and elbow with scaled rackets compared to standard rackets.

These findings are particularly important for injury prevention in young players aged 8 to 12 years. Scaled equipment reduces joint stress while maintaining, or even enhancing, performance and stroke control. Proper implementation of these adaptations in under-8, under-10, and under-12 competitions is essential for optimizing player development. Future research should investigate injury prevention in other strokes and evaluate scaled equipment’s precision and effectiveness in real-match contexts, as many studies currently focus on controlled conditions.

Studies examining the psychological effects of equipment modifications have highlighted variables such as practice commitment, enjoyment, and self-efficacy. Scaled equipment has been shown to enhance enjoyment by fostering a more aggressive playing style, which creates a more positive experience for players. Specifically, reduced net height has been associated with increased self-efficacy in beginner players, improving their success rate in serves. This improvement in performance boosts their comfort and enjoyment during practice, ultimately increasing their commitment (Gimenez-Egido et al., 2023; Timmerman et al., 2015). However, these effects were significant only for serves and did not extend to other strokes.

Kilit et al. (2024) observed that playing with green balls resulted in a more positive mood among adult beginner players, whereas using standard balls led to higher tension, fatigue, and frustration, as well as a greater perceived mental effort. Similarly, Farrow and Reid (2010) found that adapted courts and balls increased player engagement compared to standard conditions due to a higher number of opportunities and successful strokes. In contrast, Timmerman et al. (2015) reported that players exhibited more confidence with standard courts and nets, potentially due to unfamiliarity with modified conditions.

The psychological benefits of equipment modifications are especially evident in players with functional diversity. Hardoy et al. (2011) reported reduced anxiety and frustration, as well as improved self-confidence and hand-eye coordination, under adapted conditions in players with intellectual disabilities. These findings underscore the importance of further research focused on individuals with physical and mental disabilities to better understand and expand these benefits.

Insights gained from examining psychological and attitudinal variables are critical for understanding player behavior on the court and enhancing their overall experience. However, psychological variables were often treated as complementary in the studies reviewed, typically included as secondary outcomes alongside technical-tactical or physiological variables. Challenges in this area of research arise from the variability in psychological metrics studied across different articles, which complicates comparisons and interpretations. Moreover, underrepresented groups, such as adults and individuals with functional diversity, require more attention. Future studies should explore psychological and emotional variables more thoroughly across diverse player populations and investigate their interplay with related physiological variables.

Four studies in this review examined coaches’ perceptions of the International Tennis Federation’s (ITF) campaigns and the use of modified equipment, consistently highlighting a positive impact on children’s learning. Hammond and Smith (2006) conducted interviews with coaches, who unanimously praised low-compression balls for improving beginner players’ control and technique.

Using a qualitative approach, Davies (2019) found that coaches preferred the Constraints-Led Approach methodology and valued scaled equipment programs. They emphasized the importance of aligning equipment with players’ skills rather than biological age and advocated for cooperative, varied teaching methods. Cortela et al. (2019) examined the transition from green to yellow balls, revealing that individual coaches relied on specific criteria, such as impact height and grip, with the commencement of competitive play being a decisive factor.

From a quantitative perspective, Buszard et al. (2020a) evaluated professionals’ opinions on the Tennis 10s, Tennis Xpress, and ITF Play and Stay campaigns and regulatory changes. They concluded that these initiatives effectively increased tennis participation and improved key skills, particularly the forehand and backhand. Similarly, Martínez-Gallego et al. (2022) focused on the ITF Play and Stay campaign and regulatory changes in under-10 competitions. They confirmed that coaches were familiar with and applied these standards during training and competitions and had access to the necessary equipment for implementation. The study concluded that the campaign positively influenced participation and learning among beginner players.

These findings provide essential insights for federations and organizations managing grassroots and school tennis programs, highlighting the effectiveness of these campaigns and coaches’ satisfaction with their implementation. Nonetheless, future research could expand this area of inquiry by employing quantitative, qualitative, and mixed methods to deepen the understanding of coaches’ perspectives. In addition, extending the analysis to include federations and organizing bodies could offer a broader perspective on the adoption and impact of these initiatives.

These findings hold relevance for federations, clubs, and coaches, who can standardize the use of scaled equipment in training programs and competitions to facilitate beginner players’ technical progression, foster greater adherence to the sport, and improve retention rates. In under-10 competitions, events organized by federations should universalize these adaptations in their regulations to prevent injuries and promote safe tennis practice from an early age. Insights into the game structure can help clubs organize coaching programs for players of all ages. Coaches can facilitate skill acquisition by planning training sessions for beginner players that offer opportunities to focus on strategic learning and decision-making. Finally, integrating this approach into coach education programs worldwide, accompanied by certifications issued by federations, would help standardize these methodologies among professionals.