Comparing the Acute Effects of Diagonal Mobilization and Nordic Hamstring Curls on Knee Flexion and Extension Strength: A Randomized, Double-Blinded Parallel Study in Young Soccer Players

Abstract

Background: Understanding the diverse acute effects elicited by physiotherapists in soccer players may be pertinent for enhancing performance and aiding in the mitigation of injury risk. Methods: Fifty regional-level soccer players aged 13 to 15 took part in a randomized double-blind trial. They were allocated randomly to either receive diagonal manual mobilization (DM) treatment or undergo a Nordic hamstring curl (NHC) intervention, designated as the control group. Evaluations were carried out before and after the interventions to gauge standing knee extensors (KE) and knee flexors (KF) strength using the ForceFrame Strength Testing System. The recorded variables encompassed average, maximal force, and maximal impulse for both KE and KF. Results: Following the intervention, evaluations showed no significant differences between groups in KF maximal force (F_1,48 = 1.238; p = 0.271; ${\eta }_p^2$ = 0.025), KF average force (F_1,48 = 0.957; p = 0.333; ${\eta }_p^2$ = 0.020), KF maximal impulse (F_1,48 = 0.246; p = 0.622; ${\eta }_p^2$ = 0.005), KE maximal force (F_1,48 = 1.514; p = 0.225; ${\eta }_p^2$ = 0.031), KE average force (F_1,48 = 0.118; p = 0.733; ${\eta }_p^2$ = 0.002), and KE maximal impulse (F_1,48 = 2.540; p = 0.118; ${\eta }_p^2$ = 0.050). Analysis within the DM group showed significant differences in KF maximal force (24.2 N; p = 0.004), KF average force (23.4 N; p = 0.001), KE maximal force (25.8 N; p = 0.005), KE average force (20.0 N; p = 0.044), and KE maximal impulse (265.9 Ns; p = 0.027), although no significant differences were found in KF maximal impulse (150.1 Ns; p = 0.058). Conclusions: This study indicates that both DM and NHC elicit similar effects on acute responses in KE and KF strength following intervention, although DM shows more favorable adaptations within the group. Perhaps DM could serve as a suitable warm-up strategy in specific circumstances, immediately influencing readiness for strength activities.

1. Introduction

Scientific evidence highlights the critical role of appropriate knee extension (KE) and flexion (KF) force in both performance enhancement [1] and injury prevention [2] among young soccer players. Adequate knee extension strength is crucial for generating power during activities such as sprinting, jumping, and kicking, thereby enhancing athletic performance on the field [3]. Conversely, insufficient strength in knee flexors and extensors can increase the risk of injury, particularly to the anterior cruciate ligament, a common injury in soccer [4]. Research indicates that targeted strength training programs focusing on improving knee extension and flexion can significantly reduce the incidence of anterior cruciate ligament injuries in young athletes. Furthermore, maintaining a balance between these muscle groups is essential for promoting biomechanical efficiency and reducing the strain on the knee joint during dynamic movements [5], ultimately contributing to both performance optimization and injury prevention in youth soccer.

Improving muscle performance through warm-up strategies can significantly enhance the athletic readiness of participants and potentially reduce the risk of injury [6]. Various warm-up techniques have been shown to enhance proprioception and joint stability, which are vital in preventing non-contact injuries, particularly those affecting knee ligaments [7]. Including exercises that target the quadriceps, hamstrings, and hip muscles during warm-ups can optimize knee joint mechanics and alignment, thereby further decreasing the likelihood of overuse injuries throughout the season [8]. By following evidence-based warm-up protocols [9], coaches and players can actively reduce knee-related risks, promoting safer and more effective participation in soccer activities.

Among other strategies, diagonal manual mobilization (DM) can effectively enhance immediate strength and readiness in young football players, albeit through different mechanisms [10]. DM techniques, involving manual manipulation of the lower limb joints, have been shown to increase joint range of motion, proprioception, and neuromuscular excitability, potentially priming the muscles for improved performance [11]. In previous research involving young soccer athletes, the application of tissue mobilization emerged as a significant contributor to enhancing various aspects of athletic performance [12]. Findings revealed a reduction in fatigue alongside significant enhancements in fitness levels and muscular power [12]. Within the experimental cohort, which underwent soft tissue mobilization, marked improvements in knee extension and flexion were observed, particularly at speeds of 60 and 180 °/s [12]. Further reinforcing these outcomes, research conducted by Monteiro et al. [10] highlighted the efficacy of manual therapies directed towards the posterior thigh muscles. Through interventions such as manual massage and muscle energy techniques, participants exhibited enhanced performance in the ten-repetition maximum test, showcasing increased maximal load lifts [10]. However, despite these advancements, a notable research gap remains, as evidenced by the study conducted by Ghanbari and Kamalgharibi [13], which primarily explored the effects of mobilization on KE strength. This highlights the need for further investigation into the impacts of low-velocity diagonal mobilization on both knee flexors and extensors, particularly within the context of healthy soccer players.

While DM shows promise, it has not been tested against many other popular strategies. Although not specifically designed to elicit acute responses, but rather as a chronic adaptation, Nordic curl exercises directly target the hamstring muscles, possibly enhancing eccentric strength and muscle activation [14]. Studies have demonstrated that performing eccentric exercises like the Nordic curl can increase muscle activation and potentiate subsequent muscle contractions [15]. While DM may enhance overall joint function and readiness, Nordic curls specifically target hamstring strength, which is crucial for sprinting, jumping, and change of direction movements in football. By analyzing these effects, practitioners can use the evidence to determine whether it is appropriate to incorporate these strategies into warm-up or readiness routines.

Considering the reasons and possibilities mentioned above, the aim of this study was to compare the acute effects of both DM and Nordic hamstring curl (NHC) on KE and KF strength outcomes (maximal and average force; maximal impulse) in young soccer players.

2. Materials and Methods

2.1. Characteristics of the Study and Ethical Aspects

In this research, a double-blind randomized controlled design was employed. This design was chosen for its robust ability to minimize bias, as neither participants nor researchers are aware of group assignments, thereby reducing the influence of expectations on outcomes. In contrast, single-blind designs can still introduce bias from researcher influence, while non-blind designs are highly susceptible to both participant and researcher biases, making them less reliable for drawing causal inferences, which is why they were not adopted in this study. Prior to beginning, the study secured approval from the Independent Bioethics Committee for Scientific Research at the Medical University of Gdańsk. This validation, granted on 7 July 2023, under Resolution No. NKBBN 392/2023, was achieved in collaboration with the AZS Central Academic Sports Center in Gdańsk.

All participants and legal guardians were briefed on the study’s objectives and procedures, with particular emphasis on the study protocol. Prior to their involvement, written informed consent was obtained from either the parent or legal guardian. This study adhered to the ethical standards for human research delineated in the Declaration of Helsinki.

The randomization process was implemented using opaque envelopes with a 1:1 allocation ratio to ensure that all players had an equal chance of being assigned to each group. Randomization was performed by an independent researcher who was unaware of the evaluations. This randomization took place before baseline assessments and interventions to ensure allocation concealment. The interventions were administered by independent physiotherapists who were not aware of the other training processes or group assignments. These physiotherapists were specifically trained to conduct their interventions and follow the procedures precisely. Participants were also unaware of the other available groups and did not observe any of the interventions. Evaluations were conducted by researchers who were blind to the participants’ group assignments.

2.2. Participants

A priori sample size determination was conducted using G*power software (version 3.1.9.6., Universität Düsseldorf, Düsseldorf, Germany). For a two-group ANOVA repeated measures design, considering two evaluations, within-between interaction, an effect size of 0.3 (medium), and a significance level of 0.05, a power of 0.95 was aimed for. The recommended sample size generated was 40.

Recruitment was carried out at the Varsovia Football Academy within the Central Junior League, employing convenience sampling. A total of 76 potential participants were initially identified and screened against eligibility criteria, which included: (i) age between 13 and 15 years old, actively engaged in soccer practice; (ii) absence of lower limb and lumbar spine surgery or injuries within the last 6 months (hip, knee, ankle), no current pain in the hip, knee, or ankle joints, no hypermobility of the lower limb joints, and no history of neurological or connective tissue disorders; and (iii) availability for both assessment time-points. Following the exclusion of 16 participants for not meeting the age criteria and 10 for recent injuries within the last month, a total of 50 participants remained eligible for random assignment to study groups (Figure 1).

To uphold allocation concealment, randomization took place prior to the initial assessment. This process utilized a simple randomization method facilitated by the research randomizer website. To preserve the integrity of the blinding process, evaluators remained unaware of participants’ group assignments.

Fifty adolescent male soccer athletes, averaging 15.0 ± 0.9 years old, actively engaged in regional-level competition, volunteered for this study. As general anthropometric data, their average height was 167.3 ± 4.3 cm and their average body mass was 64.5 ± 2.8 kg, with an average of 4.9 ± 1.2 years of soccer training experience. They adhered to a structured regimen comprising three training sessions per week, alongside weekend matches. Each session, lasting 80 to 90 min, generally included a warm-up focused on analytical drills (such as running, dynamic stretching of the lower limbs, and coordination exercises), followed by general strength and conditioning exercises (including resistance training, aerobic exercises, or speed drills, depending on the day of the week). The session then moved to the core segment, which emphasized technical and tactical development, and concluded with small-sided and large-sided games.

2.3. Training Intervention

The intervention itself consisted of a single session performed 48 h after the latest training sessions. Participants in the experimental group received DM therapy, whereas those in the control group underwent NHC exercise led by an instructor.

Prior to the start of the intervention, participants received verbal instructions on DM, which included passive rhythmic gliding mobilization. DM, designed to enhance planned mobility through three-dimensional movements, constituted the core of the intervention. An experienced physiotherapist with 25 years of manual therapy experience conducted the mobilization consistently throughout the intervention sessions.

The procedure initiated with participants assuming a supine position, aligning their upper limbs alongside the torso. Subsequently, the therapist started mobilization of the knee joint by gently sliding the proximal tibia to enhance internal rotation (medially, cranially, dorsally). In a pronated position, mobilization of the hip joint ensued, involving the therapist’s skillful sliding of the femoral head (ventrally, medially, cephalad). Simultaneously, mobilization of the sacroiliac joint was performed by skillfully sliding the sacrum to facilitate nutation (ventrally, cephalad, laterally).

Each glide progressed to stage II until tissue tension was palpated, indicating the achievement of tissue tension sensation followed by its gentle release. Throughout the procedure, the therapist prioritized the participant’s comfort and ensured the smooth execution of the mobilization for a duration of 2 min. This therapeutic protocol was administered once per subject, resulting in a total therapy time of 6 min.

Participants in the NHC group underwent a familiarization session with the exercise program prior to the start of the study. This session, held in the week before the experimental phase, allowed the players to experience the exercises and receive individual feedback to correct their techniques and minimize bias during the intervention. It is important to note that none of the participants had prior experience with these exercises; they were introduced to them for the first time during this familiarization session. Additionally, none had previous experience with DM approaches.

The eccentric hamstring exercise protocol involved performing NHC against resistance. During the familiarization session, each participant assumed a kneeling position on the mat. They were instructed on the correct execution of the exercise, with emphasis placed on keeping their arms along their torso to ensure safe landing on the floor, and maintaining straight back and hips throughout the movement. Additionally, participants were advised to promptly report any sensations of muscle cramps to mitigate the risk of potential strains during exercise.

Each volunteer was provided with three trials to practice the exercise technique. The exercise intervention comprised 2 sets of 8 repetitions in each set, with a rest period of 60 s between sets. Throughout the session, the instructor closely monitored the participants’ execution to ensure adherence to proper form and technique.

2.4. Assessment Procedures and Tests

The evaluation process occurred in two stages: 5 min prior (pre-intervention) to and following (post-intervention) the intervention. All assessments and interventions were completed on the same day within a quiet environment, maintained at a consistent temperature of 23 °C with a relative humidity of 55%, regulated by an air conditioning system.

Initially, participants’ demographic and anthropometric data were recorded. Subsequently, a detailed verbal explanation of the study’s procedures was provided to each participant. To foster familiarity, participants were granted an initial trial of the assessment without formal recording.

To select the limb for assessment, a randomization method utilizing a “coin toss” was employed. Throughout the evaluation, two members of the research team meticulously supervised, paying particular attention to nuances in torso and pelvic posture during both landing and single-leg standing [16].

To assess the strength of the KE and KF muscles, participants underwent testing utilizing the ForceFrame Strength Testing System (Vald Performance, Brisbane, Australia). For the KE assessment, participants stood on one leg while the other leg, bent at a 30° angle, was positioned in the dynamometer’s center. Force measurements were captured using 50 Hz sensors.

Similarly, the KF assessment was conducted with participants in a standing position, with the knee flexed at 30°. The front part of the lower leg was placed in the dynamometer’s center to record force using 50 Hz sensors, while the opposite leg remained straight and served as the supporting limb.

Each movement (KE and KF) entailed maximum voluntary contractions, comprising three five-second trials with a 30 s rest period between repetitions. Data on maximum force (N), average force (N), and maximal impulse (Ns) for both limbs were collected for analysis. The average of the three recorded values was considered the result for each participant, and was subsequently uploaded to the VALD ForceFrame digital platform [17].

2.5. Statistical Analysis

To ensure the robustness of the analysis, the normality of the sample distribution was assessed and confirmed using the Kolmogorov–Smirnov test, with a resulting p-value greater than 0.05. Additionally, the assumption of homogeneity was verified through Levene’s test, yielding a p-value exceeding 0.05. Given the study’s design involving two evaluations across three distinct groups, a mixed ANOVA was employed to explore interactions between time and groups. To evaluate effect sizes within this analysis, partial eta squared (${\eta }_p^2$) was calculated. Following the mixed ANOVA, post hoc comparisons were conducted using the Bonferroni test to further elucidate any significant findings. The effect size for pairwise comparisons was calculated using Cohen’s d approach. The magnitude of the effect size was interpreted as follows [18]: 0.0–0.2 indicates a trivial effect, 0.2–0.6 indicates a small effect, and 0.6–1.2 indicates a large effect. All statistical analyses were performed using JASP software (version 0.18.3, University of Amsterdam, Amsterdam, The Netherlands), with a predetermined significance level set at p < 0.05.

3. Results

Before the intervention, evaluations showed no significant variances between groups in KF maximal force (F_1,48 = 0.041; p = 0.840; ${\eta }_p^2$ = 0.001), KF average force (F_1,48 = 0.372; p = 0.545; ${\eta }_p^2$ = 0.008), KF maximal impulse (F_1,48 = 0.607; p = 0.440; ${\eta }_p^2$ = 0.012), KE maximal force (F_1,48 = 0.005; p = 0.942; ${\eta }_p^2$ < 0.001), KE average force (F_1,48 = 0.002; p = 0.961; ${\eta }_p^2$ < 0.001), and KE maximal impulse (F_1,48 = 0.087; p = 0.769; ${\eta }_p^2$ = 0.050).

Table 1. Descriptive statistics (mean ± standard deviation) of the kinematic variables obtained pre- and post-intervention.

	Experimental Group (n = 25)	Control Group (n = 25)	Between-Groups Comparisons (Effect Size d)
KF maximal force (N)
Pre	122.4 ± 40.9	124.9 ± 43.6	0.06 (trivial)
Post	146.6 ± 34.8	133.8 ± 45.9	0.32 (small)
KF average force (N)
Pre	109.3 ± 37.6	115.8 ± 37.4	0.17 (trivial)
Post	132.7 ± 36.4	123.1 ± 33.2	0.28 (small)
KF maximal impulse (Ns)
Pre	932.2 ± 386.5	1014.9 ± 363.4	0.23 (small)
Post	1082.4 ± 384.4	1033.1 ± 314.9	0.14 (trivial)
KE maximal force (N)
Pre	177.6 ± 45.5	178.7 ± 65.3	0.02 (trivial)
Post	203.4 ± 63.9	182.4 ± 56.6	0.35 (small)
KE average force (N)
Pre	162.4 ± 33.9	163.1 ± 58.7	0.01 (trivial)
Post	182.4 ± 51.0	177.3 ± 54.0	0.10 (trivial)
KE maximal impulse (Ns)
Pre	1412.9 ± 458.8	1370.5 ± 554.4	0.08 (trivial)
Post	1678.8 ± 640.0	1410.2 ± 548.0	0.46 (small)

KE: knee extension; KF: knee flexion.

presents the descriptive statistics of the groups for both pre- and post-intervention assessments.

No significant interactions were found in KF maximal force (F_1,48 = 1.832; p = 0.182; ${\eta }_p^2$ = 0.037), KF average force (F_1,48 = 2.734; p = 0.105; ${\eta }_p^2$ = 0.054), KF maximal impulse (F_1,48 = 1.460; p = 0.233; ${\eta }_p^2$ = 0.030), KE maximal force (F_1,48 = 3.120; p = 0.084; ${\eta }_p^2$ = 0.061), KE average force (F_1,48 = 0.178; p = 0.675; ${\eta }_p^2$ = 0.004), and KE maximal impulse (F_1,48 = 1.895; p = 0.175; ${\eta }_p^2$ = 0.038).

Following the intervention, evaluations showed no significant differences between groups in KF maximal force (F_1,48 = 1.238; p = 0.271; ${\eta }_p^2$ = 0.025), KF average force (F_1,48 = 0.957; p = 0.333; ${\eta }_p^2$ = 0.020), KF maximal impulse (F_1,48 = 0.246; p = 0.622; ${\eta }_p^2$ = 0.005), KE maximal force (F_1,48 = 1.514; p = 0.225; ${\eta }_p^2$ = 0.031), KE average force (F_1,48 = 0.118; p = 0.733; ${\eta }_p^2$ = 0.002), and KE maximal impulse (F_1,48 = 2.540; p = 0.118; ${\eta }_p^2$ = 0.050). Figure 2 depicts the within-group and between-group analysis for KF variables, while Figure 3 illustrates the same for KE variables.

Analysis within the experimental group (post–pre) showed significant differences in KF maximal force (24.2 N; p = 0.004), KF average force (23.4 N; p = 0.001), KE maximal force (25.8 N; p = 0.005), KE average force (20.0 N; p = 0.044), and KE maximal impulse (265.9 Ns; p = 0.027), although no significant differences were found in KF maximal impulse (150.1 Ns; p = 0.058).

Analysis within the control group (post–pre) showed no significant differences in KF maximal force (8.9 N; p = 0.269), KF average force (7.3 N; p = 0.295), KF maximal impulse (18.1 Ns; p = 0.815), KE maximal force (3.7 N; p = 0.683), KE average force (14.2 N; p = 0.149), and KE maximal impulse (39.8 Ns; p = 0.734).

4. Discussion

Our findings revealed that both DM and NHC had similar acute effects on football players concerning KE and KF maximal strength, average strength, and maximal impulse. The results showed no significant difference between the two interventions. However, within-group analysis indicated that players exposed to DM demonstrated significant improvements in all KE outcomes after the intervention, as well as significant enhancements in maximal force and average force. Conversely, within-NHC comparisons did not reveal any significant changes from pre- to post-intervention.

Our analysis revealed that, while not differing significantly from NHC, the DM cohort exhibited marked improvements in both maximal and average strength for both KE and KF. Additionally, a noteworthy increase in maximal impulse was observed in KE. Intriguingly, the NHC group displayed no significant changes within the group, a deviation from our initial expectations.

These findings regarding the DM group echo previous research, such as the study by Ghanbari and Kamalgharibi [13], focusing on improving KE muscle strength through knee joint mobilization. Their findings indicated an 18.7% increase in KE muscle strength from pre- to post-intervention assessments, which further surged to 23.6% after a 30 min interval [13]. Similarly, another study [19] examining various low-velocity hip mobilization techniques in healthy individuals reported positive effects on gluteal muscle strength immediately post-mobilization, albeit with varying degrees of change. Subjects demonstrated a significant average increase in eccentric iliac muscle strength by 7.73% [19]. Furthermore, research targeting hip joint mobilization in knee injury patients demonstrated a 15.3% improvement in gluteus maximus muscle strength [20]. Regarding NHC, our findings partially align with studies employing a similar warm-up regimen, suggesting that the lack of significant impacts may be attributed to exercise-induced fatigue [14].

Neurophysiologically, both DM and NHC likely engage mechanisms of neural facilitation. DM techniques involve manual manipulation of muscle tissue and joints, which can stimulate mechanoreceptors and proprioceptive feedback mechanisms [21]. This sensory input can modulate neural excitability, leading to increased motor unit recruitment and synchronization, as well as improved intermuscular coordination [22]. Such neural adaptations facilitate the generation of higher force outputs during subsequent strength testing protocols. Conversely, NHC primarily challenges the hamstrings eccentrically, inducing neuromuscular adaptations specific to eccentric loading, such as increased motor unit recruitment and firing rates, as well as improved muscle spindle sensitivity [23]. However, the specificity of these adaptations to the hamstring muscles may limit their transferability to knee extension strength, explaining the lack of significant changes in KE outcomes following NHC intervention.

Biomechanically, it is expected that DM and NHC influence muscle function and joint mechanics in distinct manners due to their differing approaches and effects on muscle architecture and force transmission. DM techniques often involve dynamic stretches and specific mobilization exercises that enhance the muscle length–tension relationship and fascicle architecture. This optimization of muscle length–tension relationships can improve the ability to generate force across various joint angles, which is beneficial for tasks involving multiple muscle groups. Additionally, DM interventions are known to enhance joint mobility and alignment, leading to more efficient force transmission during strength tasks [24]. The improved joint mechanics and muscle alignment associated with DM can facilitate immediate performance gains and more effective fatigue management due to the less intense nature of the exercises compared to more targeted strength training methods [25].

In contrast, NHC focuses on the eccentric strength of the hamstring muscles by changing muscle architecture specifically related to eccentric contractions. The primary benefit of NHC is its ability to enhance eccentric strength, which is crucial for activities that involve controlled lengthening of muscles under load. However, this focus on the hamstrings means that the benefits are somewhat localized, potentially limiting the enhancement of overall knee flexion strength. Moreover, NHC exercises are characterized by their intense eccentric contractions, which can induce significant muscle damage and acute fatigue. This acute fatigue can impair short-term performance and recovery, reducing the immediate observable improvements in strength and function that might be expected from such training [26].

The acute fatigue resulting from NHC can be particularly detrimental in the short-term, as the delayed onset muscle soreness and reduced muscle function can overshadow the long-term benefits of increased eccentric strength. The localized nature of NHC’s effects and the significant muscle strain during eccentric contractions can contribute to decreased performance immediately following training sessions. In contrast, DM techniques, by focusing on broader aspects of muscle function and joint mechanics, can lead to more consistent improvements in performance and strength due to their less fatiguing nature and their ability to address multiple muscle groups simultaneously. Thus, while NHC offers valuable long-term adaptations for hamstring strength, its short-term efficacy may be compromised by acute fatigue and the specific focus on eccentric strength, unlike the more holistic benefits observed with DM interventions [24,25,26].

Furthermore, individual variability in neuromuscular activation patterns, muscle architecture, and biomechanical factors may influence the magnitude and specificity of adaptations to DM and NHC interventions. Variables such as an individual’s training status, familiarity with a complex and challenging exercise like the NHC, injury history, and anatomical variations can influence the response to these interventions [26].

While our study describes the immediate impacts of both DM and NHC interventions on the maximal strength, average strength, and maximal impulse of football players’ KE and KF, it also highlights certain limitations and areas for future exploration. The youthfulness of our participants limits the applicability of our findings to older contexts, as factors such as trainability and competitive status can affect the effectiveness of interventions. This underscores the need for broader and more diverse sample sizes, including older and elite players, as well as female athletes, to confirm and expand our results across different athlete demographics. Additionally, the short-term nature of our post-intervention assessments highlights the need for longer-term analyses to determine the sustained effects on muscle strength and performance outcomes. Therefore, it is recommended to conduct post-intervention assessments at various time-points, rather than immediately. This would involve evaluating responses at 24 and 48 h, and examining potential longer-term impacts beyond the immediate post-intervention period. Moreover, incorporating advanced measures such as electromyography and muscle architecture assessment could offer deeper mechanistic insights into the observed effects. The absence of a passive control group in our study underscores the need for future research to incorporate such conditions to better isolate the effects of the interventions. Moreover, optimizing the dosage, frequency, and timing of DM and NHC interventions, along with exploring their potential synergistic effects with other training modalities, holds promise for enhancing athletic performance.

Despite its limitations, these findings suggest that DM could offer significant benefits for augmenting acute maximal and average strength in the KE and KF muscles of football players, albeit without a statistically significant variance from NHC exercises. Coaches and trainers ought to weigh the potential efficacy of DM in bolstering muscle strength, considering its viability as a warm-up strategy in certain instances. This consideration is further supported by prior research on knee joint mobilization and hip mobilization techniques. Nevertheless, the considerable individual variability in response to interventions underscores the necessity of adopting personalized training approaches.

Our study findings present compelling insights into the acute effects of DM versus NHC interventions on football players’ KE and KF maximal and average strength, and maximal impulse. Interestingly, both interventions demonstrated similar immediate impacts on these strength variables. Although the observed benefits of DM did not manifest as a statistically significant variance from NHC exercises, coaches and trainers should consider its potential efficacy, especially given prior research supporting knee and hip mobilization techniques. Nonetheless, the substantial individual variability underscores the importance of tailoring interventions to individual needs. These findings underscore the potential of DM as a viable warm-up strategy for enhancing muscle strength, urging practitioners to carefully assess its inclusion in training protocols.

5. Conclusions

This study indicates that both DM and NHC elicit similar effects on acute responses in KE and KF strength following intervention, although DM shows more favorable adaptations within the group. Perhaps DM could serve as a suitable warm-up strategy in specific circumstances, immediately influencing readiness for strength activities.