Neuromuscular Parameters Research Articles

Effects of Explosive vs. Strength Resistance Training on Plantar Flexor Neuromuscular and Functional Capacities in Institutionalized Older Adults: A Randomized Controlled Trial

Objectives: To compare the effects of explosive and strength resistance training on neuromuscular and functional parameters in older adults and to analyze the relationship between changes in walking speed and improvements in plantar flexor (PF) neuromuscular parameters following interventions. Methods: In total, 40 participants were randomly assigned to either an explosive resistance training group (EXG, n = 18; age = 80.41 ± 10.12 years; body mass index = 22.89 ± 2.77 kg/m2) or a strength resistance training group (STG, n = 22; age = 82.89 ± 5.32 years; body mass index = 23.81 ± 3.45 kg/m2). Both groups participated in the same PF resistance training regimen (three sessions per week for 12 weeks), engaging in identical exercises. However, EXG performed three to five sets of 12 to 14 repetitions at 40% to 45% of one-maximal repetition with a rapid concentric phase and a 3 s eccentric phase, while the STG performed three to four sets of 6 to 7 repetitions at 80% to 85% of one-maximal repetition, with both phases lasting approximately 3 s. Before and after the interventions, gait speed (m/s) was assessed using a 10 m walking test, and relative maximal force (Relative Fmax, N/kg) was evaluated during maximal voluntary isometric contraction of PF. From the force–time curve, early (0–50 ms) and late (100–200 ms) rates of force development (RFD) were extracted from the linear slopes (Δ force/Δ time). Results: Gait speed significantly improved in both groups (p < 0.05). However, the improvement was more pronounced in the EXG compared to the STG (p < 0.05). Relative Fmax showed a more significant increase in the STG than in the EXG (p < 0.05). Moreover, a significant 10% increase in early RFD in the STG and a 20.1% increase in the EXG were observed (p < 0.05). The improvement in early RFD was greater in the EXG (p < 0.05). Additionally, late RFD improved significantly only in the EXG (+20.4%, p < 0.05). Conclusion: Explosive resistance training appears particularly effective in improving the ability to rapidly generate force, which is essential for many daily activities requiring explosive movements and quick responses.

An Integrated Approach to Explore Interlimb Asymmetries, Neuromuscular Parameters, and Injuries in Semiprofessional Soccer Players

An Integrated Approach to Explore Interlimb Asymmetries, Neuromuscular Parameters, and Injuries in Semiprofessional Soccer Players

Small-Sided Games with Baskets Are Significantly More Effective at Enhancing Neuromuscular Force Parameters Compared to Ball Possession Games: A Randomized Controlled Study in Young Male Basketball Players.

The aim of this study was to compare the effects of 8 weeks of small-sided basketball games (SSG) training using baskets (SSGbk) and ball possession games without baskets (SSGbpg) on various neuromuscular parameters in young male basketball players. Specifically, the study examined unilateral isometric knee flexor strength (KFS), unilateral isometric knee extensor strength (KES), bilateral countermovement jump peak power and peak landing force (CMJ), and leg land and hold test (LHT) peak landing force. This randomized controlled study included two experimental groups (SSGbk and SSGbpg) and one control group. Fifty regional competitive-level male youth basketball players (16.7 ± 0.5 years) were assigned to the groups. The experimental groups participated in two additional SSG weekly training sessions over 8 weeks. Both experimental groups were exposed to the same 2v2 to 4v4 formats of play and training volume, with the only difference being that one group performed ball possession games while the other participated in games targeting to score in the basket. Players were evaluated twice: once at baseline in the week prior to the intervention period, and again in the week post-intervention. The neuromuscular tests were conducted using force platforms. Significant interactions between time and groups were observed in KES (p < 0.001; η p 2 = 0.902), KFS (p < 0.001; η p 2 = 0.880), and CMJ peak power (p < 0.001; η p 2 = 0.630). Significant differences between groups were found post-intervention for the variables of KES (p = 0.017; η p 2 = 0.159), KFS (p = 0.011; η p 2 = 0.174), CMJ peak power (p = 0.017; η p 2 = 0.160), CMJ peak landing force (p = 0.020; η p 2 = 0.154), and LHT peak power (p = 0.012; η p 2 = 0.171). In conclusion, our study highlights that the SSGbk significantly increases neuromuscular adaptations in young male basketball players. Conversely, our findings do not support the efficacy of SSGbpg in targeting these specific physical fitness variables. Therefore, the use of SSGs must be carefully considered, particularly in selecting task conditions, to ensure efficacy in interventions.

Upper Extremity Function and Neuromuscular Parameters in Primary Headaches: A Cross-Sectional Study

Objectives: To investigate the upper extremity function, muscle strength, endurance, and proprioception in patients with primary headache compared to healthy controls. Materials and Methods: The study was completed with 37 patients with primary headache (22 patients with tension-type headache and 15 patients with migraine) and 36 healthy controls with matched age and gender. Headache severity was evaluated with the Visual Analog Scale (VAS); upper extremity function with Nine-Hole Peg Test (9-HPT); upper extremity isometric muscle strength of shoulder flexor, extensor, and elbow flexor with a hand-held dynamometer; upper extremity endurance with 6-Minute Pegboard and Ring Test (6PBRT); and upper extremity proprioception with shoulder reposition tests using Dualer IQTM digital inclinometer. Intergroup differences were examined using the Mann-Whitney U Test, and the Spearman correlation analysis was used to ascertain the relationship between the variables in headache groups. Results: There was a significant difference between the results for the 9-HPT, some upper extremity isometric muscle strength tests, 6PBRT, and shoulder reposition tests between patients with tension-type headache, migraine, and healthy controls (p&amp;lt;0.05). Except for the 9-HPT and 6PBRT (r between -0.518 and -0.645; p&amp;lt;0.05 for all), there was no significant relationship between the results for patients with tension type and migraine (p&amp;gt;0.05). Conclusion: Upper extremity function, some upper extremity muscle strength parameters, endurance, and proprioception were decreased in patients with tension-type headache and migraine compared to healthy controls, and upper extremity function was found to be associated with upper extremity endurance in these patients.

Comparison of Force, Neuromuscular, and Metabolic Responses During Sustained, Isometric Handgrip Holds to Failure Anchored to Low and High Perceptual Intensities in Men: An Exploratory Study.

Kwak, M, Succi, PJ, Benitez, B, Mitchinson, C, Samaan, MA, Abel, MG, and Bergstrom, HC. Comparison of force, neuromuscular, and metabolic responses during sustained, isometric handgrip holds to failure anchored to low and high perceptual intensities in men: An exploratory study. J Strength Cond Res 38(8): e405-e416, 2024-This study examined the responses of force alterations, relative to critical force (CF), neuromuscular parameters, and muscle oxygenation (SmO2) for isometric handgrip holds to failure (HTF) anchored to ratings of perceived exertion (RPE) of 3 and 7. Twelve men completed pre-maximal voluntary isometric contractions (pre-MVIC), submaximal HTF at 4 percentages of pre-MVIC, HTF at RPE = 3 and 7, and post-MVIC. Mechanomyograpic (MMG) signals and SmO2 were recorded during the RPE HTF. Analyses included paired-samples t-tests and repeated-measures ANOVAs at an alpha level of p ≤ 0.05. Time to task failure was not different between RPE 3 (478.7 ± 196.6 s) and RPE 7 (495.8 ± 173.8 s). Performance fatigability (PF) and MMG amplitude (AMP) were greater for RPE 7 (PF: 37.9 ± 12.9%; MMG AMP: 15.7 ± 7.4% MVIC) than RPE 3 (PF: 30.0 ± 14.5%; MMG AMP: 10.2 ± 6.5% MVIC), but MMG mean power frequency (MPF) was greater for RPE 3 (146.2 ± 31.1% MVIC) than RPE 7 (128.8 ± 23.0% MVIC). There were RPE-dependent decreases in force (p ≤ 0.01) across 3 discernable phases during the HTF. There were decreases in MMG AMP across time for both RPEs, but there were no significant changes in MMG MPF or SmO2. There were overall similar motor unit control strategies and local metabolic demand between RPEs. The majority of the HTF performed below CF at RPE 3 and 7 indicated CF did not reflect the highest sustainable force. When prescribing isometric exercise anchored to RPE, practitioners should be aware of the magnitude of force loss and relative intensity of the task to be sure desired training loads are met.

Ultrasound-guided gluteal nerves electrical stimulation to enhance strength and power in individuals with chronic knee pain: a randomized controlled pilot trial.

Various pathophysiological contexts can be accompanied by weakness, arthrogenic muscle inhibition, and even disability. In this scenario, peripheral nerve stimulation has been studied not only for pain management but also for the improvement of neuromuscular parameters. For this purpose, the use of Transcutaneous Electrical Nerve Stimulation (TENS) has typically been investigated, but recently, the use of ultrasound-guided percutaneous peripheral nerve stimulation (pPNS) has gained popularity. In this regard, electrical stimulation has a predisposition to activate Type II muscle fibers and has been shown to be capable of generating short-term potentiation by increasing calcium sensitivity. However, the evidence of pPNS applied in humans investigating such variables is rather limited. This pilot study aimed to assess the feasibility of the methodology and explore the potential of pPNS in enhancing hip extension performance in individuals suffering from knee pain, comparing it with TENS. Twelve participants were divided into pPNS and TENS groups, undergoing pre- and post-intervention assessments of peak concentric power (W), strength (N), execution speed (m/s), and one-repetition maximum (1RM) (kg) estimation. For pPNS, two needles were positioned adjacent to the superior and inferior gluteal nerves under ultrasound guidance. For TENS, electrodes were positioned between the posterosuperior iliac spine and the ischial tuberosity, and halfway between the posterosuperior iliac spine and the greater trochanter. The interventions consisted of 10 stimulations of 10 s at a frequency of 10 Hz with a pulse width of 240 μs, with rest intervals of 10 s between stimulations. Peripheral nerve stimulation significantly improved concentric power at 30% (p = 0.03) and 50% (p = 0.03) of 1RM, surpassing TENS, which showed minimal changes. No significant strength differences were observed post-intervention in either group. This work presents evidence where pPNS applied to the gluteal nerves results in an enhanced performance of hip extension at submaximal loads. However, this improvement does not seem to be reflected in short-term changes in the estimation of the 1RM by the force-velocity profile.

Aerobic Training With Blood Flow Restriction on Muscle Hypertrophy and Strength: Systematic Review and Meta-analysis.

de Lemos Muller, CH, Farinha, JB, Leal-Menezes, R, and Ramis, TR. Aerobic training with blood flow restriction on muscle hypertrophy and strength: systematic review and meta-analysis. J Strength Cond Res 38(7): 1341-1349, 2024-Integrating strength and endurance training in a single exercise session, even on separate days, can be physically demanding and time-consuming. Therefore, there is a growing interest in identifying efficient training methods that can concurrently enhance cardiovascular and neuromuscular performance through a singular training modality. This study conducted a systematic review and meta-analysis to explore the effects of aerobic training with blood flow restriction (AT + BFR) on muscle hypertrophy and strength gains in healthy individuals. Our study was registered at PROSPERO and used multiple databases (PubMed, Embase, Scopus, and Web of Science), seeking clinical trials that examined AT + BFR influence on muscle hypertrophy and strength gains in individuals aged 18-60 years and comparing with aerobic training without BFR. The risk of bias and method quality were assessed using the ROB2.0 tool and PEDro scale, respectively, and the quality of evidence was evaluated with the GRADE method. A random-effects model was used for meta-analysis, and standardized mean difference (SMD) was calculated for each outcome. Of 4,462 records, 29 full texts were assessed for eligibility, with 7 articles meeting the inclusion criteria. The results indicated that AT + BFR was more beneficial for inducing muscle hypertrophy than aerobic training without BFR (SMD [95% CI] = 0.86 [0.37-1.35]; I2 = 42%). Furthermore, AT + BFR was associated with greater improvements in muscle strength (SMD [95% CI] = 0.41 [0.10-0.72]; I2 = 0%). Despite the generally high risk of bias for both outcomes, these encouraging findings underscore the clinical significance of AT + BFR as a compelling tool for enhancing neuromuscular parameters.

Effects of high-intensity interval training and resistance training on physiological parameters and performance of well-trained runners: A randomized controlled trial

ABSTRACT This study aimed to verify the effects of 4 weeks of high-intensity interval training (HIIT), heavy (HRT) and explosive (ERT) resistance training on aerobic, anaerobic and neuromuscular parameters and performance of well-trained runners. Twenty-six male athletes were divided into HIIT (n = 10), HRT (n = 7) and ERT (n = 9) groups. Maximal oxygen uptake ( V O 2 max ) and the corresponding velocity ( vV O 2 max ), anaerobic threshold (AT), running economy (RE), oxygen uptake kinetics, lower-body strength (1RM) and power (CMJ), and the 1500m and 5000m time-trial (TT) were determined. Improvements were observed in vV O 2 max (mean difference (Δ): 2.6%; effect size (ES): 0.63) with HIIT, while AT was incresead in ERT (Δ: 4.3%; ES: 0.73) and HRT (Δ: 6.9%; ES: 0.72) groups. The CMJ performance was increased in ERT (Δ: 13.8%; ES: 1.03), HRT (Δ: 6.9%; ES: 0.55) and HIIT (Δ: 5.4%; ES: 0.34), whereas 1RM increase in HRT (Δ: 38.1%; ES: 1.21) and ERT (Δ: 49.2%; ES: 0.96) groups. HIIT improved the 1500m (Δ: −2.3%; ES: −0.62) and both HRT (Δ: −1.6%; ES: −0.32) and ERT (Δ: −1.7%; ES: −0.31) the 5000m TT. Despite performance adaptations were dependent on the training characteristics, both RT and HIIT model constitute an alternative for training periodization.

Are performance and perceived fatigability dependent on the anchor scheme of fatiguing isometric tasks in men?

Ratings of perceived exertion (RPE) can be used to regulate exercise intensity. This study examined the effect of anchor scheme on performance fatigability and neuromuscular responses following fatiguing forearm flexion tasks. Twelve men (age 20.9±2.2 years; height 179.8±5.3 cm; body mass 80.2±9.9 kg) performed sustained, isometric forearm flexion tasks to failure anchored to RPE=6 (RPEFT) and the torque (TRQFT) that corresponded to RPE=6. Pre-test and post-test maximal voluntary isometric contractions (MVIC) were performed to quantify changes in the amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals. Neuromuscular efficiency (NME) was calculated by dividing normalized torque by normalized EMG AMP. A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated measures ANOVAs were used to compare mean differences for performance fatigability and normalized neuromuscular parameters. The RPEFT had a greater TTF than the TRQFT (P<0.001). MVIC and NME decreased from pre-test to post-test following the RPEFT and TRQFT (P<0.05) with no differences between anchor schemes. Following the TRQFT, normalized EMG MPF decreased from pre-test to post-test (P=0.004). Following the RPEFT, normalized MMG MPF increased from pre-test to post-test (P=0.021). There were no changes in normalized EMG AMP or MMG AMP (P>0.05). These findings indicated anchor scheme-specific neuromuscular responses and TTF, despite no difference in performance fatigability. Furthermore, performance fatigability was likely due to peripheral fatigue (based on normalized EMG MPF and NME) following the TRQFT, but peripheral and central fatigue (based on normalized MMG MPF and NME) following the RPEFT.

The Effects of Anchoring a Fatiguing Forearm Flexion Task to a High vs. Low Rating of Perceived Exertion on Torque and Neuromuscular Responses.

Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Schmidt, RJ, and Johnson, GO. The effects of anchoring a fatiguing forearm flexion task to a high versus low rating of perceived exertion on torque and neuromuscular responses. J Strength Cond Res 38(5): e219-e225, 2024-This study examined the torque and neuromuscular responses following sustained, isometric, forearm flexion tasks anchored to 2 ratings of perceived exertion (RPE). Nine men (mean ± SD: age = 21.0 ± 2.4 years; height = 179.5 ± 5.1 cm; body mass = 79.6 ± 11.4 kg) completed maximal voluntary isometric contractions (MVIC) before and after sustained, isometric, forearm flexion tasks to failure anchored to RPE = 2 and RPE = 8. The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) signal were recorded from the biceps brachii. Normalized torque was divided by normalized EMG AMP to calculate neuromuscular efficiency (NME). A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated-measures analysis of variances was used to compare mean differences for MVIC and normalized neuromuscular parameters. There was no significant difference in TTF between RPE = 2 and RPE = 8 (p = 0.713). The MVIC decreased from pretest to posttest at RPE = 2 (p = 0.009) and RPE = 8 (p = 0.003), and posttest MVIC at RPE = 8 was less than that at RPE = 2 (p < 0.001). In addition, NME decreased from pretest to posttest (p = 0.008). There was no change in normalized EMG AMP or EMG MPF (p > 0.05). The current findings indicated that torque responses were intensity specific, but TTF and neuromuscular responses were not. Furthermore, normalized EMG AMP and EMG MPF remained unchanged but NME decreased, likely due to peripheral fatigue and excitation-contraction coupling failure. Thus, this study provides information regarding the neuromuscular responses and mechanisms of fatigue associated with tasks anchored to RPE, which adds to the foundational understanding of the relationship between resistance exercise and the perception of fatigue.

Does Obesity Affect the Rate of Force Development in Plantar Flexor Muscles among Older Adults?

The literature offers limited information on the effect of obesity on the rate of force development (RFD), a critical parameter for mobility in older adults. The objectives of this study were to explore the influence of obesity on the RFD in older adults and to examine the association between this neuromuscular parameter and walking speed. The participants (42 older adults) were classified into two groups: the control group (CG, n = 22; mean age = 81.13 ± 4.02 years; body mass index (BMI) = 25.13 ± 3.35 kg/m2), and the obese group (OG, n = 20; mean age = 77.71 ± 2.95 years; BMI = 34.46 ± 3.25 kg/m2). Walking speed (m/s) was measured using the 10 m walking test. Neuromuscular parameters of the plantar flexors were evaluated during a maximal voluntary contraction test using a dynamometer. The RFD was calculated from the linear slop of the force-time curve in the following two phases: from the onset of the contraction to 50 ms (RFD0-50) and from 100 to 200 ms (RFD100-200). The gait speed was lower in the OG compared to the CG (p < 0.001). The RFD50/100 and RFD100/200 were lower in the OG compared to the CG (p < 0.001). The RFD50/100 was found to be the predominant influencer on gait speed in the OG. In conclusion, obesity negatively impacts the RFD in older adults and RFD stands out as the primary factor among the studied parameters influencing gait speed.

Associations Between Hypertension, Angiotensin-Converting Enzyme Inhibitors, and Physical Performance in Very Old Adults: Results from the ilSIRENTE Study

BackgroundResults regarding the associations between hypertension-related parameters and physical performance in older adults are conflicting. A possible explanation for these divergent results is that investigations may not have adjusted their analyses according to the use of angiotensin-converting enzyme inhibitors (ACEIs).ObjectivesTo examine the associations between hypertension-related parameters, ACEI use, and a set of physical performance tests in very old adults.DesignCross-sectional study from the ilSIRENTE database.SettingMountain community of the Sirente geographic area (L’Aquila, Abruzzo, Italy).ParticipantsAll persons born in the Sirente area (13 municipalities) before 1 January 1924 and living in that region at the time of study were identified and invited to participate. The final sample included 364 older adults (mean age: 85.8 ± standard deviation [SD] 4.8).MeasurementsPhysical performance was assessed using isometric handgrip strength (IHG), walking speed (WS) at normal and fast pace, 5-time sit-to-stand test (5STS), and muscle power measures. Blood pressure (BP) was measured after 20 to 40 min of rest, while participants sat in an upright position. Drugs were coded according to the Anatomical Therapeutic and Chemical codes. ACEIs were categorized in centrally (ACEI-c) and peripherally (ACEI-p) acting. Blood inflammatory markers, free insulin-like growth factor 1 (IGF-1), and IGF-binding protein 3 (IGFBP-3) were assayed.ResultsResults indicated that 5STS test was significantly and negatively associated with diastolic BP values. However, significance was lost when results were adjusted for ACEI use. Participants on ACEIs were more likely to have greater specific muscle power and higher blood levels of IGFBP-3 than non-ACEI users. When participants were categorized according to ACEI subtypes, those on ACEI-p had higher blood IGF-1 levels compared with ACEI-c users.ConclusionsThe main findings of the present study indicate that ACEI use might influence the association between hypertension-related parameters and neuromuscular parameters in very old adults. Such results may possibly be linked to the effects of ACEI-p on the IGF-1 pathway.

Fatigue effects on the knee flexors neuromuscular parameters during repeated sprinting.

To identify at which point fatigue on neuromuscular parameters occurs in the knee flexors during a repeated sprint protocol. Physical active males without previous hamstring strain injury were recruited. Neuromuscular parameters such as peak torque (PT) and rate of torque development (RTD) were assessed after every two sprints in a 5 × (2 x 30m) repeated sprint protocol. Twenty physical active males participated in the study. A significant effect of sprint number was found (p < 0.001; η2p = 0.643) with a decreased sprint speed by 6.9% from fastest to slowest sprint. No significant differences were observed in the time between finishing the sprint and performing the first MVIC (46.3 ± 4.7s; p = 0.423), nor in the time between finishing a set and starting the next set (121.2 ± 7.6s; p = 0.503). Regarding neuromuscular parameters, the only significant difference found was in PT between before and after two sprints (117.95 ± 5.61N⋅m vs. 110.64 ± 5.71N⋅m; p = 0.048, d = 0.289) and on RTD 0-50ms before and after ten sprints (465.78 ± 223.76N⋅m/s vs. 382.30 ± 189.56N⋅m/s; p = 0.008; η2p = 0.149). A recovery time of 46s between sprints and testing neuromuscular parameters (due to experimental design) seems sufficient to restore the neuromuscular system. Therefore, it can be suggested that time recovery is the principal factor in detecting fatigue on neuromuscular parameters.

Effects of a Sustained, Isometric Forearm Flexion Task to Failure on Torque and Neuromuscular Responses at 3 Elbow Joint Angles

Abstract Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Anders, JPV, Schmidt, RJ, and Johnson, GO. The effects of a sustained, isometric forearm flexion task to failure on torque and neuromuscular responses at 3 elbow joint angles. J Strength Cond Res 38(1): e25–e33, 2024—This study examined the effects of a sustained, isometric forearm flexion task anchored to torque to task failure on maximal voluntary isometric contraction (MVIC) and neuromuscular responses at 3 elbow joint angles. Eleven women (mean ± SD: age = 20.8 ± 2.7 years, height = 169.3 ± 7.4 cm, body mass = 67.7 ± 6.9 kg) performed two 3s forearm flexion MVICs at elbow joint angles (JAs) of 75°, 100°, and 125° before and after a sustained, isometric forearm flexion task to failure at a fatiguing joint angle of 100° anchored to a torque value that corresponded to a rating of perceived exertion of 8 (RPE = 8). The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii. Repeated-measures ANOVAs were used to compare mean differences for MVIC and neuromuscular parameters. Collapsed across JAs, MVIC (p &lt; 0.001) and EMG MPF (p = 0.006) pretest values were greater than posttest values. Collapsed across time, EMG MPF at JA75 was greater than JA100 (p &lt; 0.001) and JA125 (p &lt; 0.001), and JA100 was greater (p = 0.007) than JA125. For EMG AMP, there was a fatigue-induced decrease at JA75 (p = 0.003). For neuromuscular efficiency (NME = normalized torque/normalized EMG AMP), there were decreases from pretest to posttest at JA100 (p = 0.002) and JA125 (p = 0.008). There were no significant interactions or main effects for MMG AMP and MMG MPF. From these findings, it was hypothesized that the decline in MVICs at JA75, JA100, and JA125 was due to fatigue-induced metabolic perturbations that resulted in JA-specific neuromuscular responses. Thus, neuromuscular parameters may provide insight into the JA-specific mechanisms of fatigue.

The Neuromuscular Parameters Affecting Static and Dynamic Balance in Adolescent Male Soccer Players with Dynamic Knee Valgus

Background and Aims The anterior cruciate ligament injury in athletes is associated with disorders related to balance and postural control. Poor balance is a predictor of lower limb injury in athletes. This study aims to investigate the different neuromuscular parameters that affect the static and dynamic balance in adolescent male football players with Dynamic Knee Valgus (DKV). Methods This is a correlational study. Participants were 83 adolescent male football players with DKV (age: 12.63±0.72 years, height: 1.69±0.07 meters, weight: 23.23±7.74 58 kg, BMI: 20.32±2.38 kg /m2), who were selected using a purposive sampling method. The presence of DKV was assessed by the squat test. The strength of the trunk and hip muscles was assessed by manual muscle testing (MMT), trunk endurance by the McGill test, and range of motion (ROM) of hip and ankle joints by a goniometer. Moreover, the static and dynamic balances were evaluated by the Bass Stick test and Y balance test, respectively. The Pearson correlation test was used to examine the relationships at a significance level of 0.05. All statistical operations were performed by SPSS software, version 24. Results The results of the present study showed a significant relationship between static balance and the study parameters (P≤0.05) except for trunk flexion strength (P=0.16) and ROM (P&lt;0.05), hip flexion ROM (P=0.83), hip extension ROM (P=0.96), hip abduction ROM (P=0.77) and ankle dorsiflexion ROM (P=0.94). The dynamic balance at anterior-posterior direction had a significant relationship with trunk endurance and left-side plank (P=0.07) and strength (P=0.05), but not with plank test score (P=0.45). The dynamic Y balance at posteromedial direction had a significant relationship with all variables except for 60° flexion (P=0.40), plank (P=0.53), left-side plank (P=0.09), and trunk extension strength (P=0.23). The results of the study also showed the significant relationship of dynamic balance at posterolateral direction and the total score of Y balance test with total trunk endurance test score (P=0.03, P=0.003) and right-side plank (P=0.005, P=0.001). Moreover, trunk extension strength and hip strength variables had a significant relationship with posterolateral dynamic balance and total Y balance test score (P≤0.05). Furthermore, the ROM of ankle dorsiflexion had a significant relationship with balance at the posteromedial (P=0.03), posterolateral (P=0.02) directions and the total Y balance score (P=0.02). Conclusion Static balance of adolescent male soccer players with DKV has a significant relationship with trunk endurance, trunk strength and thigh strength. There is a significant relationship between dynamic balance and trunk endurance, trunk strength, hip strength, and ankle dorsiflexion ROM.

Development and Interplay of Metabolic and Mechanical Performance Determinants Over an Annual Training Period in Adolescent National-Level Squad Swimmers.

The study examined the longitudinal interplay of anthropometric, metabolic, and neuromuscular development related to performance in adolescent national-level swimmers over 12months. Seven male and 12 female swimmers (14.8 [1.3]y, FINA [International Swimming Federation] points 716 [51]) were tested before (T0) and after the preparation period (T1), at the season's peak (T2), and before the next season (T3). Anthropometric (eg, fat percentage) and neuromuscular parameters (squat and bench-press load-velocity profile) were assessed on dry land. Metabolic (cost of swimming [C], maximal oxygen uptake [V˙O2peak], and peak blood lactate [bLapeak]) and performance (sprinting speed [vsprint] and lactate thresholds [LT1 and 2]) factorswere determined using a 500-m submaximal, 200-m all-out, 20-second sprint, and incremental test (+0.03m·s-1, 3min), respectively, in front-crawl swimming. vsprint (+0.6%) and LT1 and 2 (+1.9-2.4%) increased trivially and slightly, respectively, from T0 to T2 following small to moderate strength increases (≥+10.2%) from T0 to T1 and V˙O2peak (+6.0%) from T1 to T2. Bench-press maximal strength and peak power correlated with vsprint from T0 to T2 (r ≥ .54, P < .05) and LT2 at T1 (r ≥ .47, P < .05). Changes in fat percentage and V˙O2peak (T2-T1 and T3-T2, r ≤ -.67, P < .01) and C and LT2 (T2-T0, r = -.52, P = .047) were also correlated. Increases in strength and V˙O2peak from preparation to the competition period resulted in improved sprint and endurance performance. Across the season, upper-body strength was associated with vsprint and LT2, although their changes were unrelated.

Influence of different midsole foam in advanced footwear technology use on running economy and biomechanics in trained runners.

Ethylene and vinyl acetate (EVA) and polyether block amide (PEBA) are recently the most widely used materials for advanced footwear technology (AFT) that has been shown to improve running economy (RE). This study investigated the effects of these midsole materials on RE and biomechanics, in both fresh and worn state (after 450 km). Twenty-two male trained runners participated in this study. Subjects ran four 4-min trials at 13 km‧h-1 with both fresh EVA and PEBA AFT and with the same models with 450 km of wear using a randomized crossover experimental design. We measured energy cost of running (W/kg), spatiotemporal, and neuromuscular parameters. There were significant differences in RE between conditions (p = 0.01; n2 = 0.17). There was a significant increase in energy cost in the worn PEBA condition compared with new (15.21 ± 1.01 and 14.87 ± 0.99 W/kg; p < 0.05; ES = 0.54), without differences between worn EVA (15.13 ± 1.14 W/kg; p > 0.05), and new EVA (15.15 ± 1.13 w/kg; ES = 0.02). The increase in energy cost between new and worn was significantly higher for the PEBA shoes (0.32 ± 0.38 W/kg) but without significant increase for the EVA shoes (0.06 ± 0.58 W/kg) (p < 0.01; ES = 0.51) with changes in step frequency and step length. The new PEBA shoes had lower energy cost than the new EVA shoes (p < 0.05; ES = 0.27) with significant differences between conditions in contact time. There is a clear RE advantage of incorporating PEBA versus EVA in an AFT when the models are new. However, after 450 km of use, the PEBA and EVA shoes had similar RE.

Different neuromuscular parameters are associated with knee abduction and hip adduction angles during functional tasks

Knee abduction and hip adduction during functional tasks may indicate increased joint injury risk and discriminate between pathological and healthy people. Muscles’ neuromuscular variables such as amplitude (EMGAMP) and onset (EMGONSET) have been used to explain kinematics. The study aimed to evaluate the correlation between two EMG variables of seven trunk and lower limb muscles and 3D kinematics during two tasks. Eighteen physically-active women participated in the study. The following variables were obtained during single-leg squat and anterior step-down: (i) EMGAMP and EMGONSET of fibularis longus (FL), tibialis anterior (TA), vastus medialis (VM), biceps femoris (BF), gluteus medius (GMED), ipsilateral (OB_IL) and contralateral (OB_CL) external obliques and (ii) knee abduction and hip adduction angular displacement (initial angle – angle at 60° of knee flexion). Spearman’s correlation coefficient was calculated between kinematic and EMG variables. Greater knee abduction was correlated with delayed TAONSET, GMEDONSET and OB_ILONSET during step-down. Greater hip adduction was correlated with lower VMAMP, BFAMP and delayed VMONSET during step-down. Although task-specific, these results suggest that EMGONSET may influence knee abduction, while both EMGONSET and EMGAMP may affect hip adduction. The identification of muscle activation patterns in relation to kinematics may help the development of injury prevention and rehabilitation programs.

Investigation of parameters related to lower extremity muscle strength and proprioception in Patients with Multiple Sclerosis: a cross-sectional study

BackgroundPatients with Multiple Sclerosis (PwMS) may experience a decline in balance, gait, and mobility as well as an increase in fear of falling (FoF) and fatigue due to weaker muscles and proprioceptive loss in their lower limbs. The study aimed to compare lower extremity muscle strength and proprioception, balance, functional mobility, gait, FoF, and fatigue between PwMS and healthy controls and to investigate the relationship between lower extremity muscle strength and proprioception and balance, functional mobility, gait, FoF, and fatigue in PwMS. MethodsThe study was completed with 35 PwMS and 35 healthy controls with matching age and gender. The 5 Repetition Sit-to Stand Test (5-STS-test), knee and ankle reposition tests (using a digital inclinometer), the Berg Balance Scale (BBS), the Timed Up and Go (TUG) test, the Dynamic Gait Index (DGI), the Falls Efficacy-International (FES-I), and the Fatigue Severity Scale (FSS) were used for evaluations. ResultsThe 5-STS test, knee and ankle reposition tests, TUG, FES-I, and FSS Test scores were higher and BBS and DGI scores were lower in PwMS compared to healthy controls (p < 0.05). BBS, DGI, TUG, FES-I, and FSS were associated with 5-STS test and knee and ankle reposition tests except for some nondominant reposition tests in PwMS (r between 0.342 and -0.714; p < 0.05 for all). ConclusionLower extremity muscle strength and proprioception were associated with balance, functional mobility, gait, FoF, and fatigue in PwMS. These results suggested that detailed assessment of neuromuscular parameters in lower extremity function is important in determining the appropriate rehabilitation programs.

Effects of a Regular Endurance Training Program on Running Economy and Biomechanics in Runners.

A regular endurance training program may elicit different adaptations compared to an isolated training method. In this study, we analyzed the effects of 8 weeks of a regular endurance training program on running economy (RE), particularly neuromuscular and biomechanical parameters, in runners of different athletic abilities. Twenty-four male runners were divided into two groups: well-trained (n=12) and recreational (n=12). Both groups completed a 4-min running bout at 13 and 17 km·h-1, respectively, for the recreational and well-trained group, and a 5-jump plyometric test pre-post intervention. During the training program, participants completed low-intensity continuous sessions, high-intensity interval training sessions, and auxiliary strength training sessions. RE, measured as oxygen cost and energy cost, decreased by 6.15% (p=0.006) and 5.11% (p=0.043), respectively, in the well-trained group. In the recreational group, energy cost of running, respiratory exchange ratio, and leg stiffness decreased by 5.08% (p=0.035), 7.61% (p=0.003), and 10.59% (p=0.017), respectively, while ground contact time increased by 3.34% (p=0.012). The maximum height of the 5-jump plyometric test decreased by 4.55% (p=0.018) in the recreational group. We suggest that 8 weeks of regular endurance training leads to an improvement of ~5% in RE in recreational and well-trained runners with different physiological adaptations between groups and few changes in biomechanical and neuromuscular parameters only in recreational runners.