Cardiorespiratory endurance is one of the most critical indicators of physical fitness, reflecting the body’s ability to perform sustained aerobic exercise. This endurance is influenced by a combination of physiological and psychological factors. Among these, body composition, hemoglobin concentration, and motivation are often identified as potential predictors of endurance capacity. While body composition and hemoglobin are physiological markers that directly influence oxygen transport and utilization, motivation affects the intensity and persistence with which individuals engage in physical activity. Understanding how these variables interact is essential to developing holistic approaches to improving aerobic performance.

Body composition, particularly the balance between fat mass and lean mass, significantly influences cardiorespiratory fitness, as evidenced by numerous studies. Higher body fat percentages are generally linked to reduced VO₂ max, a primary marker of aerobic capacity, with research showing a consistent negative correlation between fat mass and VO₂ max across various populations, including young adults, athletes, and university rugby players (Vargas et al., 2018; Dewi et al., 2015; Shalan et al., 2024). Conversely, lean body mass, especially skeletal muscle volume, demonstrates a positive relationship with peak oxygen consumption, underscoring its role in enhancing aerobic performance even when fat mass is controlled (Karlsson et al., 2024; Maciejczyk et al., 2014). Gender differences further complicate this relationship; for instance, waist circumference has been found to negatively correlate more strongly with respiratory exchange ratio in females than in males (Karlsson et al., 2024). In athletic youth populations, such as soccer players, reductions in fat percentage have been associated with improved aerobic endurance (Nalbant & Özer, 2018). However, individual differences including age, activity levels, and genetics also play a role, and the distribution and type of muscle fibers may influence how effectively lean mass contributes to VO₂ max. Thus, optimizing cardiorespiratory fitness requires a holistic consideration of body composition alongside other physiological and lifestyle factors.

The concentration of hemoglobin is a critical physiological factor influencing aerobic performance due to its essential role in oxygen transport. Higher hemoglobin levels are positively associated with increased VO₂ max, a key indicator of aerobic capacity, as shown in multiple studies across diverse populations (Webb et al., 2023; Leoprayogo et al., 2020). For instance, research on endurance-trained cyclists has demonstrated that hemoglobin mass is linked to cardiac dimensions, further underscoring its impact on aerobic function, although this relationship becomes less predictive when adjusted for lean body mass (Ahlgrim et al., 2009). Additionally, hemoglobin levels have been shown to correlate with muscular endurance in athletes, such as soccer players, and with overall functional capacity in young adults (Octavia et al., 2018; Utami & Amani, 2023). These findings highlight the multifaceted influence of hemoglobin on physical performance, reinforcing its value as a biomarker in endurance sports.

However, aerobic performance cannot be fully explained by physiological parameters alone. Psychological factors, particularly motivation, play a pivotal role in shaping athletic outcomes. Motivation not only affects an individual's willingness to initiate and sustain physical effort but also influences training consistency, which may amplify the physiological advantages conferred by high hemoglobin levels (Martín et al., 2024). Emerging research emphasizes the importance of integrating both physiological and psychological metrics to develop a holistic understanding of endurance performance (Vyas & Khanvilkar, 2024). Metabolomic-based models now support such integration, offering deeper insights into how internal and external factors interact to optimize performance. This comprehensive approach allows for personalized training strategies that address both the body and mind, ultimately leading to more effective performance outcomes.

Despite established links between physical characteristics and aerobic performance, limited research has explored the combined predictive power of body composition, hemoglobin concentration, and motivation on cardiorespiratory endurance. Most existing studies tend to analyze these variables in isolation, without a holistic understanding of their interrelationships. While the roles of body composition and hemoglobin in influencing VO₂ max are well-documented, the impact of psychological factors such as motivation on physiological performance remains underrepresented in the literature. This study aims to fill that gap by analyzing the individual and combined influence of body composition (including body fat and lean mass), hemoglobin concentration, and motivation on cardiorespiratory endurance in a single model path analysis. The research seeks to determine whether these variables physiological and psychological can predict endurance performance more effectively when assessed together rather than separately. The findings are expected to offer valuable insights for sports scientists, coaches, and athletes by informing the design of more personalized and comprehensive training programs. Moreover, this research aligns with recent advancements in fitness science that promote the integration of biometrics, psychological factors, and metabolomic data to enhance performance prediction and optimization.

In this study, the author took a sample of 20 athletes from the entire population, with the qualification that the athletes regularly train. The results of the calculations and measurements of the mean values and standard deviations of the research variables can be seen in the table below:

Thus, based on the results of hypothesis testing with the SPSS application, the empirical causal model X1, X2, X3 with Y is visualized as follows:

The relationship between various factors and cardiorespiratory endurance was investigated in a study. Body mass index was found to have a strong positive effect with cardiorespiratory endurance (ρy1 = 0.705), indicating that individuals with higher body mass indexes tend to have better cardiorespiratory endurance. Research indicates a significant relationship between body mass index (BMI) and cardiorespiratory endurance in athletes, particularly in martial arts athletes. Studies have shown that individuals with higher BMIs tend to have better cardiorespiratory endurance (Dharma et al., 2021). This association is further supported by findings that increased body mass correlates with decreased cardiorespiratory fitness (Bonney et al., 2018). Additionally, BMI has been identified as a significant influencing parameter in cardiorespiratory endurance (Astuti et al., 2019). Moreover, the relationship between BMI and physical fitness, including cardiorespiratory fitness, has been explored in various studies (Eddolls et al., 2018; Chen et al., 2020; Firdausi & Simbolon, 2018). Higher cardiorespiratory fitness is linked to better quality of life, while overweight or obese individuals typically experience poorer quality of life (Eddolls et al., 2018). BMI has been found to be more correlated with lean body mass than other anthropometric indices and is associated with better abdominal muscular endurance and cardiorespiratory endurance (Chen et al., 2020). In the context of martial arts, maintaining an appropriate body weight and body fat rate is crucial for athletes to perform well in competitions (Sadia, H, 2022). Athletes with higher body mass indexes may experience decreased muscle strength and power, which can affect their aerobic endurance during competitions (Mardiana et al., 2019). Therefore, optimizing BMI and cardiorespiratory fitness levels is essential for enhancing the performance of martial arts athletes. In conclusion, the evidence suggests a significant relationship between BMI and cardiorespiratory endurance in athletes, highlighting the importance of maintaining appropriate body weight and composition for optimal physical performance, especially in martial arts.

Similarly, hemoglobin levels were also positively effect with cardiorespiratory endurance (ρy2 = 0.946), suggesting that individuals with higher hemoglobin levels may exhibit better cardiorespiratory endurance. Hemoglobin levels have been found to positively affect cardiorespiratory endurance in martial art athletes. Research indicates that cardiorespiratory endurance, which is the maximum capacity to utilize oxygen during physical activity, can be influenced by factors such as hemoglobin (Hb) levels and body mass index (BMI) (Astuti et al., 2019). Additionally, studies have shown that supplementing with beetroot juice may help mitigate the negative effects of hypoxia on cardiorespiratory endurance in athletes, suggesting a potential link between certain supplements and improved endurance (Domínguez et al., 2017). Furthermore, genetic factors play a role in the athletic performance of martial arts athletes, with those having higher total genetic scores demonstrating superior skill levels (Vostrikova et al., 2022). Interval training, as supported by scientific literature, has been shown to benefit athletes' endurance levels when practicing martial arts, emphasizing the importance of specific training methods in enhancing performance (Osipov et al., 2019). In addition to genetic and training factors, maintaining high levels of cardiorespiratory fitness has been associated with a reduced risk of conditions like type 2 diabetes, highlighting the importance of endurance training for overall health and performance in athletes (Someya et al., 2014). Core training has also been identified as a key factor in enhancing stability, strength, power, and endurance in martial arts athletes (Li & Du, 2023). Overall, a combination of factors including genetic predisposition, appropriate training methods, and maintaining optimal cardiorespiratory fitness levels can positively impact the endurance and performance of martial art athletes. Further research is needed to explore the intricate relationship between hemoglobin levels, cardiorespiratory endurance, and athletic performance in this specific population.

In contrast, motivation was found to have no direct effect on cardiorespiratory endurance (ρy3 = 0.087), implying that motivation levels do not significantly impact an individual's cardiorespiratory endurance. Motivation has been a key factor studied in relation to athlete performance in martial arts. While many studies have explored the impact of motivation on athletes' performance in various sports (Aftab et al., 2022), it was found that motivation does not have a direct effect on cardiorespiratory endurance in martial art athletes (Setyawati et al., 2019). This finding suggests that factors other than motivation may play a more significant role in influencing cardiorespiratory endurance in this specific group of athletes.

The lack of a significant link between motivation and cardiorespiratory endurance in athletes can be attributed to several interconnected factors, including sample homogeneity, the method of motivation assessment, and uncontrolled training variables. Athletes often demonstrate high baseline motivation due to their commitment to regular training, which may result in a homogeneous sample and mask individual differences in motivational levels (Röthlin, 2022). For instance, perseverance a dimension of achievement motivation has been linked to better endurance in young cyclists, yet such effects may be too subtle to detect in highly motivated populations (Röthlin, 2022). Additionally, motivation was measured using self-reported questionnaires, which are prone to response biases such as social desirability or lack of self-awareness, potentially compromising the accuracy of psychological assessments (Perry et al., 2017). This concern is supported by findings from McHugh (2017), who reported no significant relationship between pre-competition motivation scores and subsequent endurance performance in collegiate rowers. Another critical issue is the lack of control over training variables. Endurance adaptations are highly sensitive to training intensity and modality, and even when overall energy expenditure is equal, different training intensities can produce vastly different outcomes (Reuter et al., 2024). Without accounting for these factors, the role of motivation may appear negligible. Moreover, standardized training regimens could lead to uniform endurance levels among athletes, further diminishing the observed effect of motivation (Usharani, 2017). Similarly, while some studies report a weak but significant correlation between physical activity and endurance, they also underscore the more dominant influence of training intensity and specificity (Qhuzairi et al., 2023). Thus, while motivation is undoubtedly a component of athletic performance, its direct impact on cardiorespiratory endurance might be obscured by these methodological and contextual factors. Future research should include more robust, objective assessments of motivation and carefully controlled training conditions to better elucidate the interplay between psychological and physiological determinants of endurance.PE

Additionally, research has shown that physical fitness levels, particularly cardiorespiratory endurance, among youth athletes can vary significantly, with a considerable percentage classified in the "health risk" category (Pfeifer et al., 2019). This highlights the importance of addressing and improving cardiorespiratory fitness in athletes to ensure adequate endurance for sport participation and to mitigate potential health risks. Furthermore, studies have emphasized the importance of core strength training in enhancing flexibility, stability, and explosive strength in martial arts athletes (Feng, 2023; Haifan et al., 2023). Core strength has been linked to improved overall strength quality and standardized execution of martial arts movements, indicating its significance in optimizing athletic performance. In conclusion, while motivation is a crucial aspect of athlete performance in sports, including martial arts, the direct impact of motivation on cardiorespiratory endurance in martial art athletes may not be as pronounced as in other areas of performance. Enhancing cardiorespiratory fitness levels and focusing on core strength training are essential components in improving the physical capabilities and overall performance of martial arts athletes.

However, body mass index was positively correlated with motivation (ρ31 = 0.670), indicating that individuals with higher body mass indexes may also have higher levels of motivation. Body mass index (BMI) has been found to be positively associated with motivation, suggesting that individuals with higher BMIs may exhibit higher levels of motivation (Kaap‐Deeder et al., 2014). This relationship was further supported by a study that highlighted the positive effects of a task-oriented motivational climate and adherence to a Mediterranean diet on BMI (Castro-Sánchez et al., 2019). Additionally, a meta-analysis study indicated a positive correlation between high BMI and an increased incidence of pes planus in athletes (Resubun et al., 2022).

On the other hand, hemoglobin levels were not found to have a direct effect on motivation (ρ32 = 0.082), suggesting that hemoglobin levels do not play a significant role in determining an individual's motivation levels. On the other hand, hemoglobin levels were not directly linked to motivation levels (Kaap‐Deeder et al., 2014). However, a study revealed a direct relationship between BMI and hemoglobin levels in martial art athletes (Shah et al., 2008). Furthermore, the study revealed a direct relationship between body mass index and hemoglobin levels (ρ21 = 0.923), indicating that individuals with higher body mass indexes may also have higher hemoglobin levels. This finding suggests a potential link between body composition and blood parameters. Hemoglobin levels were associated with BMI and decreased renal function, indicating a complex interplay between these factors (Shah et al., 2008)

Overall, the results of this study highlight the complex interplay between body mass index, hemoglobin levels, motivation, and cardiorespiratory endurance. Further research is warranted to explore the underlying mechanisms driving these relationships and their implications for overall health and fitness.

This study concludes that body composition and hemoglobin levels are significant predictors of cardiorespiratory endurance among martial arts athletes, while motivation does not directly influence endurance outcomes. The strong correlation between BMI and both hemoglobin and motivation suggests an interdependent relationship among physiological and psychological variables. However, it is the physiological markers particularly hemoglobin concentration and BMI that play a more decisive role in determining aerobic performance. These findings emphasize the need for targeted training and nutritional strategies focused on optimizing body composition and blood oxygen-carrying capacity to enhance endurance. Further research with larger samples and more diverse athletic populations is recommended to generalize these results and explore deeper psychological dimensions that may indirectly impact physical performance. These findings may not be generalizable to non-bodybuilding athletes due to the specific demands of the sport.

Thank’s to Universitas Islam 45 Bekasi was recognized for their contributions to this research.

The authors declare no conflict of interest.