Contextual cues and stance decision-making in tennis forehand professional tennis players

Introduction

Performance in sports results from the interaction of numerous factors, including anthropometric, physiological, biomechanical, technical, tactical, perceptual, and psychological characteristics.^1–3 In fast-paced sports like tennis, perceptual-cognitive skills such as anticipation and decision-making are critical determinants of performance. ⁴ Players must make rapid and accurate decisions in complex, dynamically changing environments. To simplify this process, players often associate specific situations with corresponding motor responses, thereby reducing information processing time. Marteniuk ⁵ defined perceptual-cognitive expertise as the ability to identify and process environmental information and integrate it with existing knowledge to facilitate response selection.

In modern tennis, despite efforts to minimize decision-making processes to save time, players still face numerous decisions before hitting the ball. For instance, after deciding between a forehand or a backhand, they must determine the trajectory of the ball (direction, length, height, speed, and spin) and select the appropriate stance: open, square, or closed. ⁶ The quality of the stance significantly impacts performance, as it influences stability, force generation, racket velocity, and ball accuracy.^7,8 Stances are primarily distinguished by foot positioning. Some researchers have defined these positions based on permanent fixtures (e.g., net or court lines),^6–9 while others use the hitting direction as a reference. ¹⁰ This latter aspect appears more systemic, thus describing stance as “open” when the feet are nearly perpendicular to the hitting direction, “square” when the feet are parallel, and “closed” when the feet cross the hitting direction. ¹⁰ While open stance and square stance dominate during matches, closed stance is used sparingly, mainly during backhand strokes.

From a biomechanical perspective, open stance and square stance produce distinct lower and upper limb kinematics,^11–13 although no significant differences in ball or racket speed have been observed.^9,10 In high-level tennis, players alternate between square stance and open stance at various moments during a match. Considering that this additional decision-making process may require information processing time, one might question why players vary their stances instead of consistently using a single type of stance.

It can be hypothesized that, to minimize information processing time, expert tennis players have developed associations between specific visual cues and the corresponding optimal stance. For example, executing a forehand with a square stance requires an additional step, with the left foot (for right-handed players) moving in front of the right foot before striking the ball, compared to the use of an open stance. Therefore, the open stance may be the preferred choice when players perceive themselves as being under time pressure. Conversely, players may opt for a square stance when they have more time to execute the stroke. When a player has gained an advantage over their opponent and has time to act, this can be defined as a favorable situation, ¹⁴ in contrast to unfavorable situations, where players are under time pressure or in a defensive position. Finally, when players are constructing the point, they are in a neutral situation. Triolet et al. ¹⁴ defined these three game situations as the balance of power between two players and the time available to organize their response. This choice of balance of power is interesting as it groups in one variable the different factors of the incoming ball trajectory. For example, a deep and fast ball with a lot of spin will generate an unfavorable situation for the player.

Once the balance of power has been assessed, players decide on the stroke parameters (e.g., direction, length, and spin). Stroke direction, another critical factor, may influence stance selection. Studies have shown that players tend to use open stance for cross-court strokes and square stance for down-the-line strokes in controlled conditions (e.g., ball machine scenarios), outside of a match context. ¹⁵ However, during matches, stroke direction is often guided by the balance of power. For example, in defensive scenarios, players frequently opt for safer strokes, particularly when positioned off-center, increasing the likelihood of cross-court play. ¹⁶ In contrast, in offensive scenarios, players have the flexibility to choose between cross-court and down-the-line strokes. Consequently, it appears that the balance of power would have a greater influence on stance selection, with stroke direction playing a secondary role, primarily in offensive situations.

To optimize tennis performance, players and coaches must better understand how contextual information influences stance selection. Ericsson and Smith's “expert performance approach” ¹⁷ emphasizes analyzing in-situ competence among elite players as a foundational step. Given that the forehand is the most frequently used stroke in tennis, ⁶ this study aimed to investigate stance selection by elite male and female players during forehand strokes in competition. Using video analysis, we tracked two key contextual factors: the balance of power and the ball direction. The primary goal was to determine whether a priority hierarchy exists in processing contextual information that guides stance selection. If those decisions are effectively context-dependent rather than reliant on players’ physical attributes, we hypothesized that there should be no gender-based significant differences.

Materials and methods

Matches and procedures

The study was based on the analysis of video footage of matches played between 2017 and 2022 during major ATP and WTA tournaments. All matches were played on hard courts with a total of forty matches analyzed against thirty-one different opponents ranked among the top 50 according to the ATP and WTA rankings. Only video footages available on the Internet and filmed from a front-on perspective were analyzed frame-by-frame using VLC media player 3.0.12 software. The data was recorded by hand on another computer on an Excel Form.

Only forehand shots that allowed the rally to continue or led to winning the point (i.e., balls that bounced within the opponent's court) were included in the analysis. Each player performed 124 forehands (± 24.88) on average, against at least two different opponents, to reduce the potential bias of playing against a single opponent. For each situation, the balance of power, the direction of the ball, and the stance used were reported. The balance of power between two players included favorable, unfavorable, or neutral situations. ¹⁴ These situations were defined according to the relative position of the two players on the court when facing the opponent's stroke. More precisely, they defined a favorable situation when the player was very close to the baseline or inside the court, and when her/his opponent was in a difficult situation, playing the ball far behind the baseline (approximately more than 3 m) or away from the vertical mid-line on the court (approximately 4 m). A favorable position included situations when the opponent had to play the ball very close to the second bounce of the ball (at or below the level of the knees). An unfavorable situation corresponded to a response given to a stroke played by the opponent when he was positioned at least 2 m inside the court with a ball played at least at the height of the hips, or situations in which the observed player was not able to return to the center of his court ahead of the opponent's stroke. A neutral situation corresponded to a response during a rally when both players were on or behind the baseline in situations different from the ones described above.

The direction of the ball played could be either cross-court, when the ball bounced diagonally in the other half of the court, or down the line when the forehand was hit straight ahead in the other half of the court. Inside-out forehands and service returns were not analyzed.

Concerning stance analysis, this study used the hitting direction as a point of reference, as it considers the decision of the players regarding the direction of the ball. ¹⁰ Stance is said to be open when the players’ feet are almost perpendicular to the hitting direction, while in square stance, the players’ feet are parallel to the hitting direction (Figure 1).

OPEN IN VIEWER

Figure 1.

Illustration representing open stance and square stance relative to the direction of the ball played in forehand for a right-handed player based on the definition by Kawamoto et al. ¹⁰

Results

Stance and sex

First, the result of the Chi2 showed a significant Stance effect (χ² = 43,56, p = .00; open stances = 2045; square stances = 434) (Table 1).

OPEN IN VIEWER

Table 1.

Number of forehands played with open stance in each situation over the total number of forehands recorded per situation (men and women added together).

	Favorable	Neutral	Unfavorable
Straight	258 / 357	394 / 455	165 / 167
Cross	143 / 242	876 / 1015	237 / 243

Then, the result of an independent T-test on the use of open stance according to sex showed no Sex effect (t(18) = 0.433, p = .670; d = .193) (Figure 2). Indeed, men and women used mainly open stance when playing a forehand (83.62% of the time).

OPEN IN VIEWER

Figure 2.

Percentages of forehands played in open stance and square stance according to the sex.

Stance and contextual factors

Therefore, we focused on the results based on the percentage of open stance used when hitting a forehand, depending on the balance of power and the direction of the ball played (Figure 3). A ceiling effect was observed, with little to no variability in unfavorable conditions. This suggested that players consistently made the same choice in these situations, opting for an open stance. Consequently, we excluded unfavorable situations from further statistical analysis.

OPEN IN VIEWER

Figure 3.

Percentages of open stance used according to sex, balance of power, and direction of the ball played. The balance of power is given by the first letter of the condition: Favorable (F); Neutral (N); Unfavorable (U). The second letter of the condition gives the direction of the ball: Straight (S) or Crossed (C).

ANOVA on open stance revealed no Sex effect (F(1,18) = .855, p = .367, η² = .014), but separate main effects for Direction (F(1,18) = 5.609, p = .029, η² = .023), Balance of power (F(1,18) = 54.082, p < .001, η² = .354), as well as an interaction between Direction and Balance of power (F(1,18) = 8.528, p = .009, η² =  .31). Holm post hoc tests revealed a significant difference between down-the-line shots in favorable and neutral conditions (t = 4.131; p < .001), as well as between cross-court shots in favorable and neutral conditions (t = 7.635; p < .001). Additionally, post hoc tests indicated a significant difference between cross-court and down-the-line shots in favorable conditions (t = 3.727; p = .001). A decrease in the use of the open stance was observed in the favorable condition, regardless of the shot direction. This reduction was even more pronounced when players chose to hit cross-court rather than down-the-line.

Inter-Individual differences

When looking more into this favorable situation, a high variability in the use of open stance between players has been observed when playing cross-court (58.4% ± 21) and down-the-line (70.4% ± 15) (Figure 4).

OPEN IN VIEWER

Figure 4.

Players regarding their percentage of open stance in favorable situations according to the cross-court and down the line directions.

Based on the graphic, the twenty players could be classified into four distinct groups (Figure 4). In the first group, eight players used open stance to play cross-court (77.8% ± 10.2) in a similar manner to when playing down-the-line (74.9% ± 13.5). The second group of six players would also use open stance to play cross-court but less often than the first group (60% ± 6.6) and less so when hitting down-the-line (75.4% ± 6.8). The third group of four players barely used open stance to play cross-court (29.1% ± 4.7); however, in a similar manner to the other players, they adopted open stance when hitting down-the-line (70% ± 5.3). Finally, the two remaining players used open stance less than square stance, regardless of the direction of their cross-court (34.8% ± 2.1) or down-the-line strokes (37.7% ± 6.2).

Discussion

By analyzing top-level tennis players, this study tried to understand which contextual information came into play when selecting stance in tennis forehand.

First, our results showed that contextual information (i.e., balance of power and direction of the ball) are key components in choosing stances, which are mainly opened to play forehand (83,62%) in our study or in modern tennis (67% to 90% of open stance reported^6,20,21).

Indeed, we showed that tennis players used open stance almost 100% of the time when under pressure in unfavorable situations. Even in neutral situations, picking this contextual information allows for determining more than 90% of the choices made by players. Hence, our results clearly demonstrated that time pressure is a key factor in choosing an open stance, as Landlinger et al. suggested. ¹⁵ Beside the fact that open stance in defensive situations seems to carry a higher risk of knee injuries, ²² the evolution of tennis towards a more explosive and faster game may explain why the open stance is prioritized when time is lacking, as this stance requires one less step than the square stance, either in the women's or men's game. Hence, in defensive situations, the time pressure seemed to be the only factor determining stance choices, while the direction of the ball was not even taken into account. Removing the choice of stance in these situations means that high-level players associate a specific response (open stance) with a specific situation, thereby eliminating the first step of the stimulus-response association in information processing. By doing so, players reduce the time needed to plan their movements, allowing them to react faster on the court during defensive or unfavorable situations.^23,24

On the contrary, when players have more time to play (i.e., in favorable situations), they broaden their options to either an open stance or a square stance. Even though varying stances in this situation increase their reaction time, being under less time pressure allows for such flexibility. Although players use the open stance more often when playing down the line (70% ± 15) in favorable situations, other contextual information has been considered in their decision-making, which could explain the variance observed. It would be interesting to track extra contextual factors in this specific situation such as where the ball comes from, where it is played from, or whether the player is approaching the net), to determine whether each player has a specific association between context and stance in favorable situations.

This is even more obvious when looking at favorable situations where players go for a cross-court forehand, with only 58% (± 21) of open stances used. Here, we showed that the direction of the ball came into play, but the interaction between the two factors, i.e., balance of power and direction, is not sufficient to explain the choices made by the players. By analyzing players more individually, it seems that some players tend to use open stance more often regardless of the direction of the ball in favorable/offensive situations, while others favor square stance. In between, some players give priority to square stance only when playing cross-court. These differences, besides the contextual information, might come from individual factors such as the laterality profiles of the players.^25,26 This raises the question of why those players make a physical effort to take an extra step needed for square stance. It may be related to their intrinsic characteristics (anthropometric, physiological, or their natural preferences ²⁷ ), or to a greater benefit in terms of performance (speed, accuracy) that this type of stance may provide in this condition of play. Indeed, so far, the literature has only pooled all the balance of power situations together while looking at the impact of stance on ball speed, hence showing no effect on it. ¹³ More ecological studies placing players in specific situations (i.e., favorable/unfavorable) would be needed to better understand these differences.

It can also be noticed that this result is in contradiction with previous work in which square stance was supposedly the most used to play down the line in favorable situations. ¹⁵ This difference could be related to the definition of stance: stances were defined based on permanent fixtures like the net, rather than the hitting direction, as in the current study. Moreover, this latter study was not conducted in real game conditions, ¹⁵ which might not have created the ecological situation in which square stance might be adopted by players.

Secondly, even if women athletes are known to be less powerful than equally trained men, ²⁸ our results did not show differences in terms of choice of stance used. This outcome tends to confirm that this choice is linked to the context of the game and not to physical qualities.

Although more in-depth studies are needed to better understand the choices made in favorable situations, current outcomes allow us to draw some conclusions and perspectives for the training of future tennis players. Indeed, modern tennis seems too fast to allow players to make any choice while under time pressure, meaning that coaches have to teach young players, with no difference between sexes, to associate open stance with unfavorable situations. This means that recognizing such situations should be trained early on, as it is a key point when optimizing a forehand, in terms of time and technique. Moreover, our study points out that professional players might see some advantages in switching to square stance in some situations. Hence, biomechanical studies that did not find advantages between these two stances might have missed an important point. ⁹ The fact that those studies were run in laboratory settings, without any context, might have hidden the benefits of square stance. The translation of the body, only possible when using square stance, might help the player to be more accurate while keeping a good speed, for example, when the player is inside the court. It is also highly possible in such favorable situations that the role of coaches will be to figure out what the best option is for each player, based on their individual characteristics. Defining a strong association between one situation and the response (i.e., type of stance) will also be a useful strategy to save time in movement planning, hence playing faster and reducing the time for the opponent to react to the situation.

Finally, one of the limits of the current study is related to the fact that stance was only analyzed in a dichotomous manner. Players are surely using a more refined repertoire of stances, varying angles between their feet, and the direction of the ball. Using a more refined scale to analyze stances might help scientists to better understand their benefits for performance, while considering the analysis of the situation leading to the players’ decision to use or not use one specific stance.

Conclusions

In neutral and unfavorable situations, players tend to favor the open stance. Coaches can therefore focus on automating this stance in such conditions to reduce cognitive load.

In favorable situations, a more nuanced approach is required, as stance selection appears to depend on both shot direction and individual player characteristics. Further research is needed to determine which stance optimally enhances shot speed and accuracy in favorable conditions, as well as to identify the different contextual cues that influence this decision-making process.