## 3 Experimental Design
### Cluster Analysis
#### 3.3.2 Analysis of Clustering Results
Male Group Classification Cluster 1 (Group with Outstanding Overall Abilities) Students in this cluster demonstrated higher average scores across all indicators, reflecting strong overall physical fitness. Notably, their scores in the 50 m sprint, standing long jump, sit-and-reach, and 1000 m run were significantly better than those of other clusters. This group comprised 38.86% of the male students. Cluster 2 (Group with Weak Upper and Lower Limb Strength) This group showed low scores in the pull-up test (53.71 points), indicating insufficient upper limb strength. Additionally, their standing long jump scores were the lowest (78.40 points), suggesting weak lower limb explosive power. This cluster represented 17.26% of the male students. Cluster 3 (Group with Weak Aerobic Endurance and Upper Limb Strength) Students in this cluster scored poorly in the 1000 m run (59.14 points) and pull-up test (7.99 points), highlighting deficiencies in endurance and upper limb strength. This group exhibited lower overall physical fitness, accounting for 43.88% of the male students. 2. Female Group Classification Cluster 1 (Group with Weak Aerobic Endurance) This group had the lowest scores in the 800 m run (67.87 points), indicating poor endurance. This cluster comprised 35.13% of the female students. Cluster 2 (Group with Weak Core Strength)  
Figure 19: Radar chart of the average performance of students in all categories in the female group on each test item. Students in this cluster had the lowest scores in the sit-up test (17.65 points), reflecting insufficient core strength. This group accounted for 13.93% of the female students. Cluster 3 (Group with Good Overall Abilities)  
This group achieved the highest average scores across all indicators, demonstrating strong overall physical fitness. They excelled particularly in the standing long jump, 50 m sprint, and sit-up tests. This cluster represented 51.61% of the female students. Cluster 4 (Group with Weak Lower Limb Explosive Power)  
Students in this group scored the lowest in the standing long jump test (62.93 points), suggesting weak lower limb explosive power. This cluster comprised 10.32% of the female students. 3. Conclusions  
As shown in Tables 3 and 4 and Figures 18 and 19, male students were categorized into three clusters: a group with outstanding overall fitness, a group with weak upper and lower limb strength, and a group with weak aerobic endurance and upper limb strength. Female students were divided into four clusters: those with weak aerobic endurance, weak core strength, strong overall abilities, and weak lower limb explosive power. Each cluster reflects distinct physical fitness profiles, providing a basis for targeted intervention strategies. Building upon the clustering analysis results, this divergence in physical fitness trends is shaped by a combination of physiological structures, gender-specific training patterns, and test event designs. Moreover, the COVID-19 pandemic played a critical role [45; 46], as restrictions on access to sports facilities, reduced physical activity, and lack of professional guidance during this period significantly impacted students' physical condition. Pandemic-induced lifestyle changes--such as prolonged screen time, irregular sleep, and poor dietary habits--further exacerbated the decline in fitness levels, particularly among male students in strength- and endurance-based events, and among female students in flexibility-related domains. The detailed analysis revealed that, in the male group, weaknesses were primarily concentrated in upper limb strength (pull-up test) and endurance (1000 m run), particularly in Clusters 2 and 3, which together accounted for 61.14% of male students. In the female group, deficiencies were more diverse, focusing on endurance (800 m run), core strength (sit-up test), and lower limb explosive power (standing long jump).