## 3 Results  
The change of mean age in the top-100 WR players in doubles modalities over the last 27 years is presented in Figure 1. In MD, an increase in mean age was found from 1994 to 2020 (1994 = 23.91 \(\pm\) 3.93 years vs. 2020 = 25.55 \(\pm\) 4.40 years; \(p\) < 0.01). Similarly, a progressive increase of mean age was observed in XD from 1994 to 2020 (1994 = 24.06 \(\pm\) 3.99 years vs. 2020 = 25.34 \(\pm\) 4.77 years; \(p\) = 0.004). Regarding WD results, no major difference was observed between 1994 and 2020 (1994 = 23.69 \(\pm\) 4.00 years vs. 2020 = 24.08 \(\pm\) 3.58 years; \(p\) = 0.317). Within the modality comparison, mean age of MD top-100 WR players was higher than WD players in all the examined years except 1994, 1995 and 1997. Mean age of XD was higher than WD in all the examined years except 1994, 1997, 1998 and 2008. Finally, mean age of MD was higher than XD only in 2001 and 2005 (Figure 1). Figure 2 shows the mean age related to the highest ranking in badminton players. Women's doubles players reached their highest ranking earlier than both men's doubles and mixed doubles players (WD = \(\sim\)23 years, vs. MD = \(\sim\)25 years and XD = \(\sim\)25 years) in all WR position brackets. No differences were found between MD and XD players. Frequency distribution regarding age in top ranked MD, WD and XD badminton players at 1-year intervals is shown in Figure 3. It can be observed that the curves of the three modalities have an inverted U-shaped distribution, with MD and XD ranging between 20 and 27 years old and WD ranging between 19 and 26 years old. In MD, the higher rate was observed in the 21-22-years old group, in WD it was in the 20-22-years old group and for the XD it was in the 22-24-year-old group. Figure 1: Evolution of mean age in men’s doubles (MD), women’s doubles (WD) and mixed doubles (XD) badminton players present in the WR top-100 from 1994 to 2020. * Differences between MD and WD in pairwise comparisons (\(p\) < 0.05); + Differences between MD and XD in pairwise comparisons (\(p\) < 0.05). # Differences between WD and XD in pairwise comparisons (\(p\) < 0.05). Figure 3: Frequency distribution regarding age in men’s doubles (MD), women’s doubles (WD) and mixed doubles (XD) badminton players at 1-year intervals in the analysed period (1994–2020). Figure 2: Mean-age at which badminton players reached their highest position in the World Ranking. MD: men’s doubles, WD: women’s doubles and XD: mixed doubles. * Significant differences compared to WD (\(p<0.05\)). Table 1 presents the frequency distribution according to doubles players' ages in the last decades. Most badminton players, in the three modalities (MD, WD and XD) were in the 21-25 years old range for all the decades. In the MD, the range of over-30-years-old age group increased 2.62% from the 1990s to 2010s. In WD, a 2.18% decrease was found in the over-30-years-old group and a 3.33% increase in the 21-25-years-old group. In the XD, an increase of 5.86% was observed in the 21-25-years-old group. Comparing the different modalities, a greater percentage of WD players was found in the 14-20-years-old group range than in MD and XD. In addition, a larger percentage of MD were registered in the 26-30-years-old group and over-30-years-old group compared to WD, and a larger percentage of XD with respect to WD were found in the 2010s decade in the 26-30-years-old group and over-30-years-old group. MD players remained an average of 3.8 \(\pm\) 3.1 years in the top 100 WR position, WD players remained 3.4 \(\pm\) 2.7 years, while XD players remained 3.2 \(\pm\) 2.6 years. More than 59% of the doubles players (MD 59.8%, WD 64.4% and XD 67.4%) who reached the top 100 WR position remained there for 1-3 years. More than 29.0% of the doubles players (MD 33.1%, WD 31.5 and XD 29.0%) remained in the top-100 for 4-9 years and only 7.1% of MD, 4.1% of WD and 3.6% of XD stayed for 10 years or more. Figure 4 shows information concerning the percentage of badminton players from each continent in the three doubles modalities (MD, WD and XD).