## 4 Discussion  
The aim of this study was to examine the effects of NHEs on the lower limbs, specifically focusing on their relationship with absolute strength and vertical jump performance. This investigation was framed within the physical demands of various sports, including football, track and field, basketball, sport climbing, cycling, and takewondo. To ensure sample homogeneity, inclusion criteria were applied, and statistical tests, such as the Student's _t_-test, were performed, confirming the absence of significant differences prior to the intervention. The majority of participants exhibited right-side dominance. Notably, this study integrated multiple sports disciplines within a single analysis, aiming to assess whether the effects of NHEs are statistically significant and practically applicable across different sports. The findings of this study align with existing scientific literature regarding the benefits of NHEs for enhancing lower limb muscle strength, particularly in athletes recovering from injury. The Danish Society of Sports Physical Therapy (DSSF) [33] endorses the use of NHEs to improve muscular strength and reduce injury risk, citing their adaptability in terms of load and training volume. Numerous studies emphasize the efficacy of NHE in increasing eccentric strength in both male and female athletes. In this study, the intervention protocol was standardized across sexes, with identical training volume, load, and frequency. Nonetheless, the need for future research involving larger, sex-stratified samples is recognized to explore possible gender-specific responses to the intervention [37, 42]. According to [PERSON] et al. [43], age does not significantly affect the outcomes of Nordic training protocols, thereby supporting their applicability across both adolescent and adult populations (_p_ = 0.12). In line with these findings, the present study involved participants with a mean age of 18 years, ranging from 16 to 28, which reinforces the relevance of the intervention across a broad age spectrum. It is important to acknowledge, however, that body mass index (BMI) was not analyzed in this study. This decision was based on the fact that all participants were affiliated with sports federations or clubs and were under ongoing nutritional supervision by qualified professionals [44, 45, 46]. In this study, the CG exhibited an average absolute strength of 12.5 kg (118 N), with no statistically significant change observed (_p_ > 0.05). In contrast, the EG reached an average of 14.5 kg (143 N), indicating a statistically significant improvement (_p_ < 0.05). These findings align with those of [PERSON] et al. [47], who reported a significant increase in absolute strength (_p_ < 0.01) among female football players following an eight-week Nordic hamstering exercise program. This reinforces the effectiveness of the intervention in enhancing hamstering strength. With regard to vertical jump performance, [PERSON] et al. [48] suggest that this capacity can be enhanced through glyometric training programs that include bodyweight exercises and change-of-direction drills. [PERSON] and [PERSON] [49] attribute these improvements to neuromuscular adaptations, specifically the increased recruitment angles of motor units, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Strength** & **Effect** & **F** & \(p\) & \(\eta\)**p\({}^{2}\)** \\ \hline S.A dominant & T \(\times\) G & 6.63 & - & 0.04 \\ T \(\times\) S \(\times\) G & 2.74 & 0.9 & 0.01 \\ S.A non-dominant & T \(\times\) G & 8.3 & - & 0.07 \\ T \(\times\) S \(\times\) G & 0.91 & 0.5 & 0.04 \\ V.J & T \(\times\) G & 19.03 & - & 0.14 \\ T \(\times\) S \(\times\) G & 1.6 & 0.175 & 0.06 \\ \hline \hline \end{tabular} Absolute strength (S.A), vertical jump (V.J) T \(\times\) G (time: pre- and post-test EG, CG); T \(\times\) S \(\times\) G (time: pre- and post-test Sport EG, CG).  
\end{table} 
Table 5: ANOVA repeated measures for dominant and non-dominant absolute strength and vertical jump. which contribute to greater knee joint stability during jumping.