# Backward Locomotion as a Novel Strategy for Enhancing Obesity Management
## 4 Discussion  
This study examined the acute effects of forward and backward locomotion training on cardiorespiratory, metabolic, and muscle electromyography (EMG) responses in sedentary male individuals with a body mass index (BMI) \(\geq\) 30, providing novel insights into the physiological and biomechanical distinctions between these movement modalities. The strengths of this study lie in its robust methodological design and comprehensive physiological assessments. The single-group crossover design with Latin Square counterbalancing effectively minimized order effects, ensuring reliable comparisons between forward and backward locomotion conditions. The inclusion of multiple outcome measures, including cardiorespiratory (VO\({}_{2}\), VCO\({}_{2}\), heart rate), metabolic (energy expenditure,  
Figure 14: Soleus muscle %MVC values at different speeds and directions. Figure 15: Tibialis anterior muscle %MVC values at different speeds and directions. l lactate), electromyographic (EMG), and perceived exertion (RPE) data, provided a holistic understanding of acute responses in obese individuals. However, the study has limitations that warrant consideration. The sample was restricted to sedentary male participants aged 18-34 with a BMI \(\geq\) 30, limiting generalizability to females, older adults, or nonsedentary individuals. The focus on acute responses precludes conclusions about long-term effects on fitness or weight management. The findings confirm that backward locomotion imposes significantly higher cardiorespiratory and metabolic demands than forward locomotion, consistent with prior research, while offering new evidence specific to obese populations. Significant direction effects were observed for oxygen consumption (VO\({}_{2}\): F (1,26) = 398.40, \(p\) < 0.001, \(\eta^{2}\) = 0.94), carbon dioxide production (VCO\({}_{2}\): F (1,26) = 243.02, \(p\) < 0.001, \(\eta^{2}\) = 0.90), heart rate (F (1,26) = 181.79, \(p\) < 0.001, \(\eta^{2}\) = 0.87), and energy expenditure (F (1,26) = 331.07, \(p\) < 0.001, \(\eta^{2}\) = 0.92), indicating a greater physiological cost during backward locomotion. These results align with studies reporting a 30-40% higher metabolic cost in backward running due to increased step frequency and reduced stride length [14; 15; 16]. The elevated cardiorespiratory demand can be theoretically framed within the energy cost of the locomotion model, which posits that nonhabitual movement patterns, such as backward walking, require greater neural and muscular coordination, thus increasing metabolic expenditure [16]. In obese individuals, this effect is likely amplified due to the higher baseline energy costs associated with excess body mass, as noted in studies on forward locomotion [17; 18]. The increased muscle activation during backward locomotion, particularly in the tibialis anterior (percentageMVC: F (1,26) = 19.87, \(p\) < 0.001, \(\eta^{2}\) = 0.42), corroborates findings that backward running enhances the activation of anterior lower-limb muscles compared to posterior muscles like the soleus (percentageMVC: F (1,26) = 1.88, \(p\) = 0.181, \(\eta^{2}\) = 0.06) [6; 19]. The motor control theory may explain this selective activation, which suggests that backward locomotion alters muscle recruitment patterns due to reversed kinematics and increased demand for ankle dorsiflexion [20]. The lack of significant soleus activation aligns with reduced heel loading during backward locomotion, as heel-strike dominance diminishes [21]. For obese individuals, this shift in muscle recruitment could reduce stress on weight-bearing joints, supporting the hypothesis that backward locomotion is a joint-friendly exercise modality [22]. Although joint forces were not directly measured, the literature indicates lower patellofemoral compressive forces in backward running (3.0 \(\pm\) 0.6 vs. 5.6 \(\pm\) 1.3 body weight in forward running), suggesting potential benefits for obese individuals prone to joint overuse injuries [22; 23].