Isometric Peak Torque Research Articles

The Efficacy of Blood Flow Restriction Training to Improve Quadriceps Muscle Function after ACL Reconstruction.

Blood flow restriction training (BFRT) is a popular rehabilitation intervention after anterior cruciate ligament reconstruction (ACLR). However, there are a lack of clinical trials establishing the efficacy of using BFRT during rehabilitation to improve quadriceps muscle function. To evaluate the efficacy of blood flow restriction training to improve quadriceps muscle strength, morphology, and physiology, and knee biomechanics in individuals after ACLR in a double-blind, randomized, placebo-controlled clinical trial (NCT03364647). 48 athletes (20 females/28 males) were randomly assigned to low-load strength training with active BFRT or standard of care strength training with a sham unit. Treatment occurred for 1-month pre-surgery and 4-5 months post-surgery with both groups following the same standard rehabilitation protocol. Outcome variables were measured at baseline and 4-5 months post-surgery. Quadriceps muscle strength (isometric and isokinetic peak torque and rate of torque development) was measured on an isokinetic dynamometer. Quadriceps muscle morphology (physiological cross-sectional area, fibrosis) was determined using magnetic resonance imaging. Quadriceps muscle physiology (fiber type, fiber cross-sectional area, satellite cell abundance, collagen content, fibro-/adipo-genic progenitor cells) was evaluated with muscle biopsies of the vastus lateralis. Knee extensor moment and knee flexion angle were measured via three-dimensional gait analysis. Change scores were calculated as: post-intervention-baseline. Two sample t-tests were then used to assess between-group differences for each outcome variable. No significant between-group differences were found for any outcome variable. The addition of BFRT to a rehabilitation program for athletes pre- and post- ACLR was no more effective than standard rehabilitation for improving quadriceps muscle function. Clinicians should consider the value of BFRT relative to the cost, time, and discomfort for patients in light of these results.

Biosponge-Encased Placental Stem Cells for Volumetric Muscle Loss Repair.

Objective: Volumetric muscle loss (VML) leads to permanent muscle mass and functional impairments. While mesenchymal stromal cells (MSCs) and their secreted factors can aid muscle regeneration, MSCs exhibit limited persistence in injured tissue post-transplantation. Human placental-derived stem cells (hPDSCs), sharing surface markers with MSCs, demonstrate superior regenerative potential due to their fetal origin. Previously, a biosponge (BS) scaffold was shown to augment muscle regeneration post-VML. This study aims to coapply BS therapy and hPDSCs to further enhance muscle recovery following VML. Approach: A VML defect was created by removing ∼20% of the tibialis anterior muscle mass in male Lewis rats. Injured muscles were either left untreated or treated with BS or BS-encapsulated hPDSCs cultured under normoxic or hypoxic conditions. On day 28 postinjury, peak isometric torque was measured, and the muscle was harvested for analysis. Results: BS encapsulated hPDSCs subjected to hypoxic preconditioning persisted in larger quantities and enhanced muscle mass at day 28 postinjury. BS encapsulated hPDSCs cultured under normoxic or hypoxic conditions increased small myofibers (<500 µm2) percentage, MyoD protein expression, and both pro- and anti-inflammatory macrophage marker expression. BS encapsulated hPDSCs also reduced fibrosis and BS remodeling rate. Innovation: This study is the first to examine the therapeutic effects of hPDSCs in a rat VML model. A BS carrier and hypoxic preconditioning were investigated to mitigate low cell survival postimplantation. Conclusion: hPDSCs augment the regenerative effect of BS. Combining hPDSCs and BS emerges as a promising strategy worthy of further investigation.

Deceleration Capacity During Directional Change as a Time-Efficient (Ecological) Prescreening of Hip Adductor Force Status in Amateur Soccer Players.

Miralles-Iborra, A, Del Coso, J, De Los Ríos-Calonge, J, Elvira, JLL, Barbado, D, Urban, T, and Moreno-Pérez, V. Deceleration capacity during directional change as a time-efficient (ecological) prescreening of hip adductor force status in amateur soccer players. J Strength Cond Res XX(X): 000-000, 2024-Reduced isometric adductor muscle strength has been identified as a modifiable risk factor contributing to injury in soccer players. However, the measurement of hip adductor muscle strength is habitually laboratory-based, with isolated hip movements that do not reflect soccer-specific movements that induce groin injury during match play. This study aimed to determine the usefulness of deceleration capacity during a change of direction (COD) as a time-efficient (ecological) prescreening of hip adductor force status in soccer players. Nineteen amateur soccer players completed unilateral isometric hip adductor strength assessments and a 180° COD test. Isometric hip strength assessment included the maximum peak torque (PT) and maximum rate of torque development (RTDmax) relative to players' body mass. Players' deceleration capacity during the COD test was determined for each leg through maximum deceleration normalized to the linear momentum. A linear regression analysis was performed to associate isometric hip strength variables with the deceleration capacity during the COD test at each leg. There was not a statistically significant association between deceleration capacity and hip isometric maximum PT of the dominant and nondominant legs (r ≤ 0.14, p > 0.05). Nevertheless, a moderate association was found between deceleration capacity and RTDmax for both legs (r ≥ 0.58, p < 0.05). The optimal linear regression model suggests that measuring deceleration capacity during a directional change test could explain RTDmax by 33 and 43% for the dominant and nondominant legs, respectively. During a 180° COD test, the deceleration capacity captured through GPS-accelerometer device was limited as a prescreening tool to evaluate hip adductor force status in soccer players.

High-intensity interval training with functional electrical stimulation cycling for incomplete spinal cord injury patients: A pilot feasibility study.

Consequences of spinal cord injury (SCI) with a sedentary lifestyle will progress to muscle weakness and muscle atrophy, leading to muscle fatigue. This study aimed to determine the feasibility and preliminary effects of high-intensity interval training (HIIT) using functional electrical stimulation (FES) cycling on changes in thigh muscle volume and muscle strength, in patients with incomplete SCI. Eight incomplete SCI patients (mean age 50 years; 6 women) with stable SCI paraplegia (mean 6.75 years since injury) participated in the HIIT FES cycling (85%-90% peak Watts; 4 × 4-min intervals) three times a week (over 6 weeks). The main outcomes were adherence, participant acceptability, and adverse events. Secondary outcomes were muscle strength (peak torque) and leg volume changes. Our findings revealed that the program was well-received by participants, with high levels of adherence, positive feedback, and satisfaction, suggesting that it could be a promising option for individuals seeking to enhance their lower body strength and muscle mass. Additionally, all participants successfully completed the training without any serious adverse events, indicating that the program is safe for use. Finally, we found that the 6-week HIIT FES leg cycling exercise program resulted in notable improvements in isometric peak torque of the quadriceps (range 13.9%-25.6%), hamstring muscle (18.2%-23.3%), and leg volume (1.7%-18.2%). This study highlights HIIT FES leg cycling exercise program potential as an effective intervention for improving lower limb muscle function.

Reliability of lower limb strength assessment in female team sport athletes

BackgroundLower limb injury rates have increased dramatically in line with increased female sport participation levels. Muscle strength is a modifiable lower limb injury risk factor, guiding performance monitoring and rehabilitation. ObjectivesThe aim of this study was to investigate the test-retest reliability of isokinetic and isometric lower limb peak torque to body mass of muscles acting on the hip, knee, and ankle in female team sport athletes. It was hypothesised the test-retest reliability would be good (intraclass correlation coefficients (ICC) ≥ 0.75). MethodsThirty-eight female athletes (Australian Rules Football = 18, netball = 12, soccer = 8) aged 16–35 years participated in this study. Participants performed isokinetic (60°/s and 120°/s) and isometric testing on a Biodex Isokinetic Dynamometer on three separate days. ResultsPoor to good reliability was demonstrated for all joint movements (ICC = 0.38–0.88) with small to moderate effect sizes (0.00–0.43) and typical errors (5.65–24.49). ConclusionDifferences in peak torque to body mass were observed between sessions one and two and/or one and three, demonstrating a learning effect. Therefore, three testing sessions, and/or the inclusion of a familiarisation session, is recommended for future assessments in populations unfamiliar with dynamometry.

Combined regenerative rehabilitation improves recovery following volumetric muscle loss injury in a rat model.

Volumetric muscle loss (VML) injury causes irreversible deficits in muscle mass and function, often resulting in permanent disability. The current standard of care is physical therapy, but it is limited in mitigating functional deficits. We have previously optimized a rehabilitation technique using electrically stimulated eccentric contraction training (EST) that improved muscle mass, strength, and size in VML-injured rats. A biosponge scaffold composed of extracellular matrix proteins has previously enhanced muscle function postVML. This study aimed to determine whether combining a regenerative therapy (i.e., biosponge) with a novel rehabilitation technique (i.e., EST) could enhance recovery in a rat model of VML. A VML defect was created by removing ~20% of muscle mass from the tibialis anterior muscle in adult male Lewis rats. Experimental groups included VML-injured rats treated with biosponge with EST or biosponge alone (n = 6/group). EST was implemented 2 weeks postinjury at 150 Hz and was continued for 4 weeks. A linear increase in eccentric torque over 4 weeks showed the adaptability of the VML-injured muscle to EST. Combining biosponge with EST improved peak isometric torque by ~52% compared with biosponge treatment alone at 6 weeks postinjury. Application of EST increased MyoD gene expression and the percentage of large (>2000 μm2) type 2B myofibers but reduced fibrotic tissue deposition in VML-injured muscles. Together, these changes may provide the basis for improved torque production. This study demonstrates the potential for combined regenerative and rehabilitative therapy to improve muscle recovery following VML.

Effect of Spirulina Nigrita® Supplementation on Indices of Exercise-Induced Muscle Damage after Eccentric Protocol of Upper Limbs in Apparently Healthy Volunteers.

Spirulina is a supplement with antioxidant and anti-inflammatory properties that may enhance performance and recovery after intense exercise. The present study aimed to investigate the effects of Spirulina Nigrita® on physical performance, and recovery markers after intense eccentric exercise in healthy moderately physically active volunteers. In a double-blind crossover design, participants were supplemented either with spirulina (42 mg Kg-1 BW per day) or a placebo for 15 days before conducting an eccentric exercise protocol using the non-dominant arm. A six-week washout period was required between conditions. Performance and mobility markers such as isometric peak torque (PTQ), ligament range of motion (ROM), and perceived muscle discomfort (VAS) were assessed and blood samples (CK, LDH) were obtained at 1, 24, 48, and 72 h post-exercise. No significant differences were noticed between the two conditions on any of the investigated markers, indicating that spirulina supplementation has no positive effect on isometric muscle performance or alleviation of exercise-induced muscle damage (EIMD) symptoms in the specific population.

Combined action observation and mental imagery versus neuromuscular electrical stimulation as novel therapeutics during short-term knee immobilization.

Limb immobilization causes rapid declines in muscle strength and mass. Given the role of the nervous system in immobilization-induced weakness, targeted interventions may be able to preserve muscle strength, but not mass, and vice versa. The purpose of this study was to assess the effects of two distinct interventions during 1 week of knee joint immobilization on muscle strength (isometric and concentric isokinetic peak torque), mass (bioimpedance spectroscopy and ultrasonography), and neuromuscular function (transcranial magnetic stimulation and interpolated twitch technique). Thirty-nine healthy, college-aged adults (21 males, 18 females) were randomized into one of four groups: immobilization only (n=9), immobilization + action observation/mental imagery (AOMI) (n=10), immobilization + neuromuscular electrical stimulation (NMES) (n=12), or control group (n=8). The AOMI group performed daily video observation and mental imagery of knee extensions. The NMES group performed twice daily stimulation of the quadriceps femoris. Based on observed effect sizes, it appears that AOMI shows promise as a means of preserving voluntary strength, which may be modulated by neural adaptations. Strength increased from PRE to POST in the AOMI group, with +7.2% (Cohen's d=1.018) increase in concentric isokinetic peak torque at 30°/s. However, NMES did not preserve muscle mass. Though preliminary, our findings highlight the specific nature of clinical interventions and suggest that muscle strength can be independently targeted during rehabilitation. This study was prospectively registered: ClinicalTrials.gov NCT05072652.

Validity of a commercially available load cell dynamometer in measuring isometric knee extension torque in patients with knee disorders

ObjectiveAssess the validity of hand-held dynamometry (HHD) and the Tindeq Progressor (TP) in assessing peak isometric knee extension torque and limb symmetry index (LSI) versus isokinetic dynamometer (IKD). DesignProspective cross-sectional study. SettingLaboratory. Participants31 individuals with unilateral knee disorders (21 female; 28.3 ± 11 years). Main outcome measuresPeak isometric knee extension torque; Knee extension LSI. ResultsStrong to almost perfect (p < 0.001) correlations (Cohen's Kappa k) with IKD were found for both devices for peak torque of the uninvolved limb (HHD [k = 0.84], TP [k = 0.91]) and involved limb (HHD [k = 0.93], TP [k = 0.98]). For LSI, moderate to strong (p < 0.001) correlations with IKD were found for HHD (k = 0.79) and TP (k = 0.89). Mean bias errors were equivalent for determining LSI (HHD = 0.02%; TP = 0.03%). Both HHD and TP were highly sensitive (96.2–100.0%) and specific (100.0%) at the 70% LSI threshold. TP showed higher sensitivity and specificity at the 90% LSI threshold. ConclusionHHD and TP are valid in measuring isometric knee extension torque with the reference standard IKD. TP showed superior validity in identifying LSI. TP also shows greater specificity in identifying the 90% LSI threshold.

Lower limb muscles’ thicknesses are weakly associated with dynamic knee valgus during single-leg squat in women with patellofemoral pain

IntroductionPatellofemoral pain (PFP) patients often show an altered lower limb alignment during the single-leg squat (SLS). There is evidence that proximal and distal-to-the-knee muscle alterations can modify the lower limb alignment in PFP patients. However, we observed a lack of studies investigating the possible association between the thickness and strength of proximal and distal-to-the-knee muscles and lower limb alignment during SLS in women with PFP. Therefore, this study aimed to investigate the association between the thickness and strength of lower limb muscles and dynamic knee valgus (DKV) during SLS in women with PFP. MethodsCross-sectional study, where fifty-five women with PFP were submitted to the following evaluations: (1) muscle thickness (MT) of Gluteus Medius (GMed), Gluteus Maximus (GMax), Vastus Lateralis (VL), and Tibialis Anterior (TA); (2) isometric peak torque of hip abductors, hip external rotators, knee extensors, and foot inversors; and (3) DKV during SLS. ResultsThere was a significant negative association between GMax's MT and DKV (r = −0.32; p = 0.01), and between TA's MT and DKV (r = −0.28; p = 0.03). No significant correlations were observed between isometric torques and DKV. Regression analysis found that GMax's MT explained 10% of the DKV's variance during SLS. DiscussionPoor lower limb alignment during SLS is weakly associated with proximal and distal-to-the-knee muscle thicknesses, with no association with isometric torque in PFP women. ConclusionOur results suggest that other factors besides strength and muscle thicknesses may explain and improve lower limb alignment in women with PFP.

Sex Differences in Quadriceps Atrophy After Anterior Cruciate Ligament Tear.

Female athletes lag behind their male counterparts in recovery from anterior cruciate ligament (ACL) injury. Quadriceps muscle size and strength are crucial factors for regaining function after ACL injury, but little is known about how these metrics vary due to biological sex. Female patients have reduced vastus lateralis fiber cross-sectional area (CSA) and lower quadriceps strength after ACL injury than male patients. Cross-sectional study. Level 4. A total of 60 participants with recent ACL tear were evaluated for vastus lateralis muscle fiber CSA, isometric quadriceps peak torque, and quadriceps rate of torque development. Linear mixed models were fit to determine differences across sex and limb for each variable of interest. The female group averaged almost 20% atrophy between limbs (P < 0.01), while the male group averaged just under 4% (P = 0.05). Strength deficits between limbs were comparable between female and male groups. Immediately after ACL injury, female patients have greater between-limb differences in muscle fiber CSA but between-limb strength deficits comparable with those of male patients. These results indicate that the underpinnings of strength loss differ based on biological sex, and thus individual patients could benefit from a sex-specific treatment approach to ACL injury.

Cross-Education Effects of Isokinetic Eccentric Plantarflexor Training on Flexibility, Strength, and Muscle-Tendon Mechanics.

Large increases in joint range of motion (ROM) have been reported after eccentric resistance training; however, limited data exist describing the associated mechanisms or potential cross-education effects in the contralateral limb. Therefore, the effects of a 6-wk isokinetic eccentric plantarflexor training program were examined in 26 participants. Before and after the training program, dorsiflexion ROM, plantarflexor strength, and muscle-tendon unit (MTU) morphology and mechanics were measured in control ( n = 13) and experimental ( n = 13) young adult groups. Training consisted of 5 sets of 12 maximal isokinetic eccentric plantarflexor contractions twice weekly on the right limb. Significant ( P < 0.05) increases in dorsiflexion ROM (4.0-9.5°), stretch tolerance (40.3-95.9%), passive elastic energy storage (47.5-161.3%), and isometric (38.1-40.6%) and eccentric (46.7-67.0%) peak plantarflexor torques were detected in both trained and contralateral limbs in the experimental group. Significant increases in gastrocnemius medialis and soleus thickness (5.4-6.1%), gastrocnemius medialis fascicle length (7.6 ± 8.5%), passive plantarflexor MTU stiffness (30.1 ± 35.5%), and Achilles tendon stiffness (5.3 ± 4.9%) were observed in the trained limb only. Significant correlations were detected between the changes in trained and contralateral limbs for dorsiflexion ROM ( r = 0.59) and both isometric ( r = 0.79) and eccentric ( r = 0.73) peak torques. No significant changes in any metric were detected in the control group. Large ROM increases in the trained limb were associated with neurological, mechanical, and structural adaptations, with evidence of a cross-education effect in the contralateral limb being primarily driven by neurological adaptation (stretch tolerance). The large improvements in ROM, muscle size, and strength confirm that isokinetic eccentric training is a highly effective training tool, with potential for use in athletic and clinical populations where MTU function is impaired and current therapies are ineffective.

Multimodal and conventional resistance training interventions improve muscle function in older adults: Findings from the Training IMCT study

Age-associated remodeling processes affect the intramuscular connective tissue (IMCT) network, which may significantly impair muscle function. Thus, we aimed to test whether including exercises shown to efficiently target the IMCT to a conventional resistance exercise intervention (CONV) would result in greater functional gains as compared to CONV alone. Fifty-three men and women (66.2 ± 3.3 years) were assigned to either CONV (n = 15), multimodal training (MULTI; n = 17) or a control (CTRL; n = 21) group. All subjects were tested at baseline, and those assigned to CONV or MULTI underwent a 16-week training intervention. The CONV group followed a progressive resistance training program, in which the number of weekly training sessions gradually increased from 1 to 3. In the MULTI group, one of these sessions was replaced with plyometric training, followed by self-myofascial release. Testing included maximal strength and power, imaging-based muscle volume, architecture, and functional performance. The intervention effects were analyzed using two- or three-way repeated measures ANOVA models (α = 0.05). Briefly, the maximal knee extension isometric contraction, one-repetition maximum, and isokinetic peak torque increased in all groups (p < 0.05), albeit to a lesser extent in CTRL. On the other hand, quadriceps femoris muscle volume (p = 0.019) and vastus lateralis pennation angle (p < 0.001) increased only in the MULTI group. Handgrip strength did not change in response to the intervention (p = 0.312), whereas Sit-to-Stand performance improved in all groups after the first 8-wks, but only in MULTI and CONV after 16-wks (all p < 0.001). In conclusion, we found that a resistance training intervention in which one weekly training session is replaced by plyometric training is feasible and as effective as a program consisting solely of conventional strength training sessions for inducing gains in muscle strength and function in older adults. Muscle size and architecture improved only in the MULTI group. German Clinical Trials: DRKS00015750.

Normative values for isometric quadriceps peak torque using fixed dynamometry in healthy young adults

RATIONALE: Assessment of muscle strength is recommended to measure weakness and inform exercise prescription in adults undergoing pulmonary rehabilitation. There is a lack of normative data for lower extremity muscle strength using fixed dynamometry in the clinical setting in young adults. OBJECTIVES: Primary objectives were to determine (i) normative values for isometric quadriceps peak torque (QT) using fixed dynamometry and (ii) the relationship between isometric QT with demographics, body composition, habitual physical activity and one-repetition maximum (1-RM) for knee extension. A secondary objective was to develop a preliminary equation to predict 1-RM knee extension using isometric QT. METHODS This was a cross-sectional study of healthy adults aged 18–39 years. Isometric QT was assessed using fixed dynamometry (MedUp®). A 1-RM test was performed in the same setting. Age, sex and body composition using bioelectiral impedance analysis (Tanita, DC-430U) were collected. Physical activity was assessed by the Rapid Assessment of Physical Activity (RAPA). RESULTS Eighty-two participants were included (44 females, 54%). Isometric QT was 89 (77-132) Nm for females and 158 (133-187) Nm for males (p < 0.0001). There was a strong correlation between isometric QT and 1-RM (r = 0.85, p < 0.0001). The multi-linear regression model to predict 1-RM included sex, isometric QT and BMI (F (3, 78) = 60.819; p < 0.001; R 2 = 0.701). CONCLUSION Normative isometric QT values to quantify lower limb strength impairment and a preliminary equation using isometric QT to predict 1-RM and prescribe resistance quadriceps exercise training may inform pulmonary rehabilitation programs for a younger respiratory population. Validation of the 1-RM equation in clinical populations is needed.

Ab. No. 156 Exercise Intolerance in Individuals With Long Covid: A Cross-Sectional Analysis

Introduction: Long-COVID has emerged as a significant public health burden, affecting millions around the world. Exercise intolerance is a prominent symptom of Long-COVID and understanding its underlying mechanisms can help health professionals determine appropriate rehabilitation strategies. The aim is to determine potential causes of exercise intolerance in individuals with Long-COVID. Methods: Fifteen individuals (age=31±11years;87% female) with a confirmed COVID-19 diagnosis in the past and Post-Covid Functional Status ≥2 were included. Following ethical approval and informed consent, participants underwent a series of assessments including 6-min walk test, PFT, Echocardiography, Cardiopulmonary exercise testing (CPET) and Isometric peak torque (IPT). A symptom limited graded CPET was conducted on two consecutive days(Vyntus CPX System) on cycle ergometer using a standardized ramp protocol. IPT was determined using Humac Norm Isokinetic Device at 90º of knee flexion, with 10seconds hold for 3sets between 2-7days post CPET. Result: VO2peak was 20.6±4.8ml/kg/min (RER:1.2±0.1; peakHR:166±22; MVV%:62±10) and significantly lower than predicted values. IPT of dominant quadriceps was 113.4±44.6Nm. All participants terminated exercise due to lower extremity fatigue and inability to maintain peddling rate. Only seven (47%) participants exceeded 90%of their age-predicted MHR and only two crossed 70% of their predicted MVV; indicating possibility of peripheral contribution to exercise intolerance. This could be corroborated by significant moderate correlation between VO2peak and IPT (r=0.66, p=0.008). Conclusion: This sample of participants with Long-COVID had significantly lower VO2peak than predicted with a possible contribution from peripheral skeletal/neural processes that present as exercise intolerance. Implications: Peripheral causes of exercise intolerance also need to be considered while developing appropriate rehabilitation strategies.

A Single Dose of Microencapsulated Cocoa Supplementation Does Not Speed up Muscle Force Recovery after Eccentric Exercise-Induced Muscle Damage: A Placebo-Controlled, Double-Blind, Crossover Study

Exercise-induced muscle damage is associated with symptoms such as inflammation, delayed-onset muscle soreness, and impaired muscle performance. The intake of cocoa polyphenols has been suggested to improve muscle recovery due to their antioxidant and anti-inflammatory capacity. However, their bioavailability presents a challenge. Therefore, food microencapsulation may be an alternative to protect polyphenols, ensuring their biological effects. This study aimed to investigate the effect of a single dose of microencapsulated cocoa on the changes in muscle damage markers after eccentric exercise. In this randomized, double-blind, crossover study, fourteen healthy volunteers with previous resistance training experience performed 6 × 10 maximal isokinetic eccentric contractions of their elbow flexors using an isokinetic dynamometer after ingesting 25 g of microencapsulated cocoa or placebo. Peak isometric torque was measured using maximal voluntary isometric contractions, and pain was measured using a visual analogic scale both before and 24 h, 48 h, and 72 h after the damage protocol. Plasma glutathione and malondialdehyde levels were measured using high-performance liquid chromatography, and concentrations of myoglobin and C-reactive protein were determined using a fluorescence immunoassay analyzer. Significant decreases were seen in the peak isometric torque and pain measures from pre- to 72 h post-eccentric exercise. A significant main effect for time was found only for plasma myoglobin at 2 h, 48 h, and 72 h, and for C-reactive protein at 2 h, compared to the pre-eccentric exercise values. No significant time-treatment effects were observed (all p &gt; 0.05). This study demonstrated that microencapsulated cocoa cannot improve muscle recovery after eccentric exercise, at least when a single dose is consumed.

The Influence of Strength Level on Handball-Specific Fitness Elements Between Stronger and Weaker Professional Players.

Kyriacou-Rossi, A, Hadjicharalambous, M, and Zaras, N. The influence of strength level on handball-specific fitness elements between stronger and weaker professional players. J Strength Cond Res 38(5): 966-975, 2024-The aim of the study was to investigate the influence of strength level between stronger and weaker handball players on handball specific fitness elements and to explore the correlations between strength and sport-specific fitness elements. Twenty-one professional male handball-players (age: 25.9 ± 6.9 years; mass: 87.9 ± 13.9 kg; height: 1.81 ± 0.08 m), participated in the study. Players were divided into the stronger (SG) and weaker group (WG) according to their relative to body mass 1 repetition maximum strength (1RM). Measurements included body composition, countermovement jump (CMJ), isometric leg extension peak torque (IPT) and rate of torque development (RTD), 5-step long-jump, 0-20 m linear sprint, T-half test, throwing velocity, and 1RM in bench press and squat. No significant difference was found for body composition between SG and WG ( p > 0.05). However, SG had significantly higher CMJ height (21.5%, p = 0.002), IPT (22.4%, p = 0.008), RTD relative to body mass ( p < 0.05), 5-step long jump (10.9%, p = 0.005), lower 0-20 linear sprint (-6.3%, p = 0.012), lower T-half test time trial (-7.3%, p = 0.001), and higher throwing velocity compared with WG ( p < 0.05). When all players included in one group, large to very large correlations were found between 1RM strength and IPT with fat-free mass ( r = 0.518-0.774) and throwing velocity ( r = 0.472-0.819). Very large correlations were found between RTD with fat-free mass ( r = 0.760) and throwing velocity ( r = 0.780-0.835). Stronger players have greater performance in all handball-fitness attributes compared with their weaker counterparts. The significant correlations between handball-specific fitness elements with strength and RTD suggest that strength training is essential for handball players as it may link to higher on court performance.

Which Tests Predict 6-Month Isokinetic Quadriceps Strength After ACL Reconstruction? An Examination of Isometric Quadriceps Strength and Functional Tests at 3 Months.

Restoration of quadriceps strength after anterior ligament reconstruction (ACLR) is a persistent challenge for patients and clinicians. Inadequate recovery of quadriceps strength has been linked to increase risk of re-injury. Developing methods of early identification of strength deficits is essential to allow clinicians to provide more individualized interventions early in the rehabilitation process. To determine whether 3-month isometric quadriceps strength, the Y-Balance Test (YBT), and the anterior step-down test are predictive of isokinetic quadriceps strength at six months in adolescents after ACLR. Retrospective cohort. Thirty-six adolescent patients with primary ACLR (58% female, 36% with concomitant meniscal repair, age: 15.7 ± 1.6 years). At three months post-operative, isometric quadriceps strength via isokinetic dynamometer, YBT-Lower Quarter, and anterior step-down tests were completed. At six months post-operative, an isokinetic knee strength assessment was completed. Regression analysis was used to evaluate the predictive relationship between 3-month isometric tests and 6-month isokinetic knee extension tests. Three-month post operative isometric quadriceps peak torque predicted isokinetic quadriceps peak torque at 6 months, F(1,34) = 19.61, p <0.001. Three-month isometric quadriceps peak torque accounted for 36.6% of the variance in normalized isokinetic quadriceps peak torque at 6 months with adjusted R2 = 34.7%. Including YBT anterior reach (β = 0.157, p = 0.318) in regression added 1.9% of variance when predicting 6-month isokinetic quadriceps peak torque, F (2,33) = 10.32, p <0.001, R2 = 0.385, ΔR2 = 0.019. At three months post-ACLR, isometric strength testing appears more optimal than other functional tests in predicting isokinetic quadriceps peak torque in later stages of rehabilitation for adolescents. Clinicians should use tests at three months that measure quadriceps strength if aiming to predict isokinetic quadriceps peak torque at six months post-ACLR, rather than using functional tests such as the YBT-LQ or anterior step-down. Level 3.

Reactive Strength Index, Rate of Torque Development, and Performance in Well-Trained Weightlifters: A Pilot Study.

The purpose of this study was to investigate the correlation between the reactive strength index (RSI) using the drop jump (DJ) and the isometric rate of torque development (RTD) with weightlifting performance in national-level weightlifters. Seven male weightlifters (age: 28.3 ± 5.7 years, body mass: 80.5 ± 6.7 kg, body height: 1.73 ± 0.07 m) participated in this study. Measurements were performed 2 weeks prior to the national championship and included the countermovement jump (CMJ), the squat jump (SJ), the DJ from three different drop heights (20, 30, and 40 cm), and the isometric peak torque (IPT) and RTD. Performance in CMJ and SJ was significantly correlated with weightlifting performance (r ranging from 0.756 to 0.892). Significant correlations were found between weightlifting performance with DJ contact time (r ranging from -0.759 to -0.899) and RSI (r ranging from 0.790 to 0.922). Moreover, the best RSI was significantly correlated with the snatch (r = 0.921, p = 0.003) and total performance (r = 0.832, p = 0.020). Small to very large correlations were found between IPT and RTD with weightlifting performance (r ranging from 0.254 to 0.796). These results suggest that RSI and contact time variables from DJ may predict weightlifting performance in well-trained weightlifters. Additionally, IPT and RTD may provide useful insights into the neuromuscular fitness condition of the weightlifter.

Applicability of the seated step test for assessing thigh muscle sarcopenia in older individuals

Assessment of lower limb muscle mass and related functions in older individuals is important because of their essential role in maintaining locomotion and activities of daily living. Therefore, a simple and reliable method for assessing these parameters should be established. The seated step test is easy and safe and can be used to assess lower limb agility; however, its relationship to skeletal muscle mass and function remains unknown. The present study aimed to investigate the relationships between the seated step test and lower limb muscle mass and function. For the analysis, we included 85 participants aged 73.1 ± 6.0 years. The participants performed an alternate up-down leg step test for 10 s while seated in a chair. Lower limb muscle mass was measured using bioimpedance analysis. Skeletal muscle mass index (SMI) was calculated using the following equation: lower limb muscle mass (kg) / height2 (m2). As the muscle functional parameters, we measured the isometric knee extension peak torque (KEPT), knee flexion peak torque (KFPT), and rate of torque development (RTD) for isometric knee extension in all participants. The seated step test score had a significant relationship with KEPT, KFPT, and SMI, but not with RTD. In the single regression analysis, the seated step test significantly predicted KEPT, KFPT, and SMI. These results suggest that up-down seated step test can be a reliable method to estimate lower limb muscle size and function in older individuals.