Assessment of arthrogenic quadriceps muscle inhibition by physical examination in the supine position during isometric contraction is feasible as demonstrated by electromyography: a cross-sectional study.

BACKGROUND: Preventing severe arthrogenic muscle inhibition (AMI) after knee injury is critical for better prognosis. The novel Sonnery-Cottet classification of AMI enables the evaluation of AMI severity but requires validation. This study aimed to investigate the electromyography (EMG) patterns of leg muscles in the examination position from the classification during isometric contraction to confirm its validity. We hypothesised that the AMI pattern, which is characterised by quadriceps inhibition and hamstring hypercontraction, would be detectable in the supine position during isometric contraction. METHODS: Patients with meniscal or knee ligament injuries were enrolled between August 2023 and May 2024. Surface EMG was assessed during submaximal voluntary isometric contractions (sMVIC) at 0° extension in the supine position for the vastus medialis (VM) and vastus lateralis (VL) muscles and at 20° flexion in the prone position for the semitendinosus (ST) and biceps femoris (BF) muscles. Reference values for normalisation were obtained from the EMG activity during the gait of the uninjured leg. The Kruskal-Wallis test was used to compare the activation patterns of the muscle groups within the same leg, and the post-hoc tests were conducted using the Mann-Whitney U test and Bonferroni correction. RESULTS: Electromyographic data of 40 patients with knee injuries were analyzed. During sMVIC, the extensor and flexor muscles of the injured leg showed distinct behaviours (P < 0.001), whereas the uninjured side did not (P = 0.144). In the injured leg, the VM differed significantly from the ST (P = 0.018), and the VL differed significantly from the ST and BF (P = 0.001 and P = 0.026, respectively). However, there were no statistically significant differences within the extensor muscle groups (VM and VL, P = 0.487) or flexor muscle groups (ST and BF, P = 0.377). CONCLUSION: AMI was detectable in the examination position suggested by the Sonnery-Cottet classification. The flexor and extensor muscles of the injured leg exhibited distinct activation behaviours, with inhibition predominantly occurring in the quadriceps muscles, whereas the hamstrings showed excitation.

Adjunctive hiking bouts during 8 weeks regular sailing training improves cardiorespiratory and muscular responses during hiking emulation in highly trained sailors.

To investigate the effects of 8-week hiking bench training on cardiorespiratory and muscular responses of highly trained sailors during hiking emulation. Twenty-four sailors were assigned into two groups: the hiking bench training group (HTG, n = 12) and the control group (CG, n = 12). Both groups maintained their regular training with the HTG performed two additional hiking bench training sessions per week for 8 weeks, while the CG performed an equivalent duration of on-water sailing training. Physiological responses were assessed by performing four successive 3-min hiking bouts on a sailing emulation ergometer before and after the 8-week training period. Comparing the pretest, both groups exhibited a significant decrease (p < 0.05) in the percentage of maximal oxygen uptake (%VO2max) and maximal heart rate (%HRmax); the HTG experienced a greater decrease in %VO2max in bouts 2 and 3. The root mean square (RMS) of rectus femoris (RF), vastus lateralis (VL), rectus abdominis (RA), and external oblique decreased significantly (p < 0.05), whereas the mean power frequency (MPF) of RF, VL, and RA exhibited an increasing trend. The RMS of RF and RA in HTG were lower than those in CG in the initial three bouts; VL and EA in HTG were lower than those in CG in bouts 1 and 2 (p < 0.05). The MPF of RA in HTG was significantly increased in bouts 2, 3, and 4 (p < 0.05). Eight-week hiking bench training could improve hiking economy and the activation of lower limb and trunk muscles delaying the onset of fatigue in sailors.

Resistance exercise training to improve post-operative rehabilitation in knee arthroplasty patients: A narrative review.

Knee osteoarthritis is associated with deficits in muscle strength, muscle mass, and physical functioning. These muscle-related deficits are acutely exacerbated following total knee arthroplasty (TKA) and persist long after surgery, despite the application of standardized rehabilitation programs that include physical/functional training. Resistance exercise training (RET) has been shown to be a highly effective strategy to improve muscle-related outcomes in healthy as well as clinical populations. However, the use of RET in traditional rehabilitation programs after TKA is limited. In this narrative review, we provide an updated view on whether adding RET to the standard rehabilitation (SR) in the recovery period (up to 1 year) after TKA leads to greater improvements in muscle-related outcomes when compared to SR alone. Overall, research findings clearly indicate that both muscle strength and muscle mass can be improved to a greater extent with RET-based rehabilitation compared to SR. Additionally, measures of physical functioning that rely on quadriceps strength and balance (e.g., stair climbing, chair standing, etc.) also appear to benefit more from a RET-based program compared to SR, especially in patients with low levels of physical functioning. Importantly though, for RET to be optimally effective, it should be performed at 70%-80% of the one-repetition maximum, with 3-4 sets per exercise, with a minimum of 3 times per week for 8 weeks. Based upon this narrative review, we recommend that such high-intensity progressive RET should be incorporated into standard programs during rehabilitation after TKA.

Effect of Sampling Rate, Filtering, and Torque Onset Detection on Quadriceps Rate of Torque Development and Torque Steadiness.

Quadriceps rate of torque development (RTD) and torque steadiness are valuable metrics for assessing explosive strength and the ability to control force over a sustained period of time, which can inform clinical assessments of knee function. Despite their widespread use, there is a significant gap in standardized methodology for measuring these metrics, which limits their utility in comparing outcomes across different studies and populations. To address these gaps, we evaluated the influence of sampling rates, signal filtering, and torque onset detection on RTD and torque steadiness. Twenty-seven participants with a history of a primary anterior cruciate ligament reconstruction (N = 27 (11 male/16 female), age = 23 ± 8 years, body mass index = 26 ± 4 kg/m2) and thirty-two control participants (N = 32 (13 male/19 female), age = 23 ± 7 years, body mass index = 23 ± 3 kg/m2) underwent isometric quadriceps strength testing, with data collected at 2222 Hz on an isokinetic dynamometer. The torque-time signal was downsampled to approximately 100 and 1000 Hz and processed using a low-pass, zero-lag Butterworth filter with a range of cutoff frequencies spanning 10-200 Hz. The thresholds used to detect torque onset were defined as 0.1 Nm, 1 Nm, and 5 Nm. RTD between 0 and 100 ms, 0 and 200 ms, and 40-160 ms was computed, as well as absolute and relative torque steadiness. Relative differences were computed by comparing all outcomes to the "gold standard" values computed, with a sampling rate of 2222 Hz, a cutoff frequency in the low-pass filter of 150 Hz, and torque onset of 1 Nm, and compared utilizing linear mixed models. While all combinations of signal collection and processing parameters reached statistical significance (p < 0.05), these differences were consistent between injured and control limbs. Additionally, clinically relevant differences (+/-10%) were primarily observed through torque onset detection methods and primarily affected RTD between 0 and 100 ms. Although measurements of RTD and torque steadiness were generally robust against diverse signal collection and processing parameters, the selection of torque onset should be carefully considered, especially in early RTD assessments that have shorter time epochs.

Fast and slow myofiber nuclei, satellite cells, and size distribution with lifelong endurance exercise in men and women.

We previously observed lifelong endurance exercise (LLE) influenced quadriceps whole-muscle and myofiber size in a fiber-type and sex-specific manner. The current follow-up exploratory investigation examined myofiber size regulators and myofiber size distribution in vastus lateralis biopsies from these same LLE men (n = 21, 74 ± 1 years) and women (n = 7, 72 ± 2 years) as well as old, healthy nonexercisers (OH; men: n = 10, 75 ± 1 years; women: n = 10, 75 ± 1 years) and young exercisers (YE; men: n = 10, 25 ± 1 years; women: n = 10, 25 ± 1 years). LLE exercised ~5 days/week, ~7 h/week for the previous 52 ± 1 years. Slow (myosin heavy chain (MHC) I) and fast (MHC IIa) myofiber nuclei/fiber, myonuclear domain, satellite cells/fiber, and satellite cell density were not influenced (p > 0.05) by LLE in men and women. The aging groups had ~50%-60% higher proportion of large (>7000 µm2) and small (<3000 µm2) myofibers (OH; men: 44%, women: 48%, LLE; men: 42%, women: 42%, YE; men: 27%, women: 29%). LLE men had triple the proportion of large slow fibers (LLE: 21%, YE: 7%, OH: 7%), while LLE women had more small slow fibers (LLE: 15%, YE: 8%, OH: 9%). LLE reduced by ~50% the proportion of small fast (MHC II containing) fibers in the aging men (OH: 14%, LLE: 7%) and women (OH: 35%, LLE: 18%). These data, coupled with previous findings, suggest that myonuclei and satellite cell content are uninfluenced by lifelong endurance exercise in men ~60-90 years, and this now also extends to septuagenarian lifelong endurance exercise women. Additionally, lifelong endurance exercise appears to influence the relative abundance of small and large myofibers (fast and slow) differently between men and women.

Smart Bioimpedance Device for the Assessment of Peripheral Muscles in Patients with COPD.

Muscle dysfunction and muscle atrophy are common complications resulting from Chronic Obstructive Pulmonary Disease (COPD). The evaluation of the peripheral muscles can be carried out through the assessment of their structural components from ultrasound images or their functional components through isometric and isotonic strength tests. This evaluation, performed mainly on the quadriceps muscle, is not only of great interest for diagnosis, prognosis and monitoring of COPD, but also for the evaluation of the benefits of therapeutic interventions. In this work, bioimpedance spectroscopy technology is proposed as a low-cost and easy-to-use alternative for the evaluation of peripheral muscles, becoming a feasible alternative to ultrasound images and strength tests for their application in routine clinical practice. For this purpose, a laboratory prototype of a bioimpedance device has been adapted to perform segmental measurements in the quadriceps region. The validation results obtained in a pseudo-randomized study in patients with COPD in a controlled clinical environment which involved 33 volunteers confirm the correlation and correspondence of the bioimpedance parameters with respect to the structural and functional parameters of the quadriceps muscle, making it possible to propose a set of prediction equations. The main contribution of this manuscript is the discovery of a linear relationship between quadriceps muscle properties and the bioimpedance Cole model parameters, reaching a correlation of 0.69 and an average error of less than 0.2 cm regarding the thickness of the quadriceps estimations from ultrasound images, and a correlation of 0.77 and an average error of 3.9 kg regarding the isometric strength of the quadriceps muscle.

Effects of weight-bearing dance aerobics on lower limb muscle morphology, strength and functional fitness in older women.

Objective: To investigate the effects of 12-week weight-bearing dance aerobics (WBDA) on muscle morphology, strength and functional fitness in older women. Methods: This controlled study recruited 37 female participants (66.31y ± 3.83) and divided them into intervention and control groups according to willingness. The intervention group received 90-min WBDA thrice a week for 12 weeks, while the control group maintained normal activities. The groups were then compared by measuring muscle thickness, fiber length and pennation angle by ultrasound, muscle strength using an isokinetic multi-joint module and functional fitness, such as 2-min step test, 30-s chair stand, chair sit-and-reach, TUG and single-legged closed-eyed standing test. The morphology, strength, and functional fitness were compared using ANCOVA or Mann-Whitney U test to study the effects of 12 weeks WBDA. Results: Among all recruited participants, 33 completed all tests. After 12 weeks, the thickness of the vastus intermedius (F = 17.85, P < 0.01) and quadriceps (F = 15.62, P < 0.01) was significantly increased in the intervention group compared to the control group, along with a significant increase in the torque/weight of the knee flexor muscles (F = 4.47, P = 0.04). Similarly, the intervention group revealed a significant improvement in the single-legged closed-eyed standing test (z = -2.16, P = 0.03) compared to the control group. Conclusion: The study concluded that compared to the non-exercising control group, 12-week WBDA was shown to thicken vastus intermedius, increase muscle strength, and improve physical function in older women. In addition, this study provides a reference exercise program for older women.

Chronic Adaptions in Quadriceps Fascicle Mechanics Are Related to Altered Knee Biomechanics After Anterior Cruciate Ligament Reconstruction.

Following anterior cruciate ligament reconstruction (ACLR), patients exhibit abnormal walking mechanics and quadriceps dysfunction. Quadriceps dysfunction has been largely attributed to muscle atrophy and weakness. While important, these factors do not capture intrinsic properties of muscle that govern its ability to generate force and withstand load. While fascicle abnormalities after ACLR have been documented in early stages of recovery (<12 mo), long-term effects of ACLR on fascicle mechanics remain unexplored. We evaluated quadriceps fascicle mechanics during walking 3 years post-ACLR and examined the relationship with knee mechanics. Participants included 24 individuals with ACLR and 24 Controls. Linear mixed models compared the ACLR, Contralateral, and Controls limbs for (1) quadriceps strength, (2) fascicle architecture and mechanics, and (3) knee mechanics. No difference in strength or overall fascicle length excursions was found between limbs. The ACLR limb exhibited longer fascicles at heel strike and peak knee extension moment (P < .001-.004), and smaller fascicle angles at heel strike, peak knee extension moment, and overall suppressed fascicle angle excursions (P < .001-.049) relative to the Contralateral and/or Control limb. This indicates an abnormality in fascicle architecture and mechanics following ACLR and suggests abnormalities in contractile function that cannot be explained by muscle weakness and may contribute to long-term gait irregularities.

Effect of resistance training on quadriceps femoris muscle thickness obtained by ultrasound: A systematic review with meta-analysis.

OBJECTIVE: The present study aimed to determine the magnitude and intervention time of resistance training required to generate adaptations in the muscle thickness of the quadriceps muscle obtained by ultrasound in healthy adults. METHOD: A systematic review with meta-analysis was conducted on studies recovered from Pubmed, Web of Science, and Scopus databases up to March 2022. The study selection process was carried out by two independent researchers, with the presence of a third researcher in case of disagreements. The methodological quality of the studies was determined with the TESTEX scale, and the risk of bias analysis was determined using Cochrane's RoB 2.0 tool. The meta-analysis used the inverse of the variance with a fixed model, and the effect size was reported by the standardized mean difference (SMD) with a confidence interval of 95%. RESULTS: Ten studies were included in a meta-analysis. The overall analysis of the studies demonstrated an SMD = 0.35 [95% CI: 0.13-0.56] (P = 0.002), with a low heterogeneity of I2 = 0% (P = 0.52). No publication bias was detected using a funnel plot followed by Egger's test (P = 0.06). The degree of certainty of the meta-analysis was high using the GRADE tool. CONCLUSION: We found that resistance training can generate significant average increases of 16.6% in muscle thickness obtained by ultrasound in the quadriceps femoris muscles of healthy adults. However, the subgroup analysis showed that significant effect sizes were only observed after eight weeks of training.

The Duration of Non-Local Muscle Fatigue Effects.

Non-local muscle fatigue (NLMF) refers to a transient decline in the functioning of a non-exercised muscle following the fatigue of a different muscle group. Most studies examining NLMF conducted post-tests immediately after the fatiguing protocols, leaving the duration of these effects uncertain. The aim of this study was to investigate the duration of NLMF (1-, 3-, and 5-minutes). In this randomized crossover study, 17 recreationally trained participants (four females) were tested for the acute effects of unilateral knee extensor (KE) muscle fatigue on the contralateral homologous muscle strength, and activation. Each of the four sessions included testing at either 1-, 3-, or 5-minutes post-test, as well as a control condition for non-dominant KE peak force, instantaneous strength (force produced within the first 100-ms), and vastus lateralis and biceps femoris electromyography (EMG). The dominant KE fatigue intervention protocol involved two sets of 100-seconds maximal voluntary isometric contractions (MVIC) separated by 1-minute of rest. Non-dominant KE MVIC forces showed moderate and small magnitude reductions at 1-min (p < 0.0001, d = 0.72) and 3-min (p = 0.005, d = 0.30) post-test respectively. The KE MVIC instantaneous strength revealed large magnitude, significant reductions between 1-min (p = 0.021, d = 1.33), and 3-min (p = 0.041, d = 1.13) compared with the control. In addition, EMG data revealed large magnitude increases with the 1-minute versus control condition (p = 0.03, d = 1.10). In summary, impairments of the non-exercised leg were apparent up to 3-minutes post-exercise with no significant deficits at 5-minutes. Recovery duration plays a crucial role in the manifestation of NLMF.

Effectiveness of the Copenhagen adduction modified position stage 1: EMG measurements and hand-held dynamometer analysis in young and healthy men.

OBJECTIVES: To verify the effectiveness of the use of a modified position of the Copenhagen Adduction (CA) stage 1 compared to the original position. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: 31 healthy men aged 23.7 ± 1.9 years with no recent or chronic general pathology. MAIN OUTCOME MEASURES: Differences between EMG amplitudes for the adductor longus (AL), rectus femoris (RF) and semi tendinous (ST) during dynamic contractions and adductor maximal isometric voluntary contraction (MIVC) force values between CA stage 1 standard and modified positions were assessed with either Wilcoxon or paired t-test. RESULTS: No significant differences were observed for EMG amplitudes of the AL (p-value = 0.724) and for the RF muscle (p-value = 0.337) and for the adductor force (p-value = 0.361) between the two positions. A significant difference was obtained for the ST (p-value<0.001) mainly explained by the adapted position of the non-dominant leg which unlocked the hip joint and generated less muscle activity in the hamstrings. CONCLUSIONS: Muscle activity of the AL muscle and adductor force being similar in both positions, the CA stage 1 modified position could be of interest for rehabilitation after adductor injury or strengthening of the adductors in elite athletes.

Immediate effects of kinesiology tape on quadriceps muscle peak torque and knee joint repositioning error in healthy males: Effects of different tensions and directions.

BACKGROUND: Knee joint injuries may result from compromised quadriceps muscle strength or diminished knee joint proprioception. The application of Kinesio tape (KT) on the quadriceps muscle from origin to insertion (OTI-KT) or insertion to origin (ITO-KT) could impact knee joint proprioception and quadriceps muscle strength. This study aims to assess the effects of different tensions and directions of KT application on active and passive knee joint repositioning errors (AJRE and PJRE) and peak concentric and eccentric peak torque (CPT and EPT) of the quadriceps muscles in healthy males. METHOD: Twenty-one healthy males participated in this repeated-measures study design. CPT, EPT, AJRE, and PJRE of the dominant limb were measured by a Biodex dynamometer before and after applying OTI-KT with 0%, 15%, and 40% extra tensions and ITO-KT with 0% tension. RESULTS: ITO-KT demonstrated a significant reduction in AJRE (p < 0.05). Meanwhile, for OTI-KT, a statistically significant difference was observed in both AJRE and PJRE concerning time (F1,126 = 19.74, p < 0.05 for AJRE; F1,126 = 9.96, p < 0.05 for PJRE) and tension (F2,126 = 22.14, p < 0.05 for AJRE; F2,126 = 20.67, p < 0.05 for PJRE). CONCLUSION: Applying KT, especially OTI KT with 40% and 15% extra tension, shows potential in enhancing knee proprioception without immediate impacts on quadriceps muscle torque. This suggests applications in sports performance and knee injury rehabilitation.

Neuromuscular Adaptations in Endurance-Trained Male Adolescents Versus Untrained Peers: A 9-Month Longitudinal Study.

BACKGROUND: Neuromuscular function is considered as a determinant factor of endurance performance during adulthood. However, whether endurance training triggers further neuromuscular adaptations exceeding those of growth and maturation alone over the rapid adolescent growth period is yet to be determined. OBJECTIVE: The present study investigated the concurrent role of growth, maturation, and endurance training on neuromuscular function through a 9-month training period in adolescent triathletes. METHODS: Thirty-eight 13- to 15-year-old males (23 triathletes [~6 h/week endurance training] and 15 untrained [<2 h/week endurance activity]) were evaluated before and after a 9-month triathlon training season. Maximal oxygen uptake (V̇O2max) and power at V̇O2max were assessed during incremental cycling. Knee extensor maximal voluntary isometric contraction torque (MVCISO) was measured and the voluntary activation level (VAL) was determined using the twitch interpolation technique. Knee extensor doublet peak torque (T100Hz) and normalized vastus lateralis (VL) electromyographic activity (EMG/M-wave) were also determined. VL and rectus femoris (RF) muscle architecture was assessed using ultrasonography. RESULTS: Absolute V̇O2max increased similarly in both groups but power at V̇O2max only significantly increased in triathletes (+13.8%). MVCISO (+14.4%), VL (+4.4%), and RF (+15.8%) muscle thicknesses and RF pennation angle (+22.1%) increased over the 9-month period in both groups similarly (p < 0.01), although no changes were observed in T100Hz, VAL, or VL EMG/M-wave. No changes were detected in any neuromuscular variables, except for coactivation. CONCLUSION: Endurance training did not induce detectible, additional neuromuscular adaptations. However, the training-specific cycling power improvement in triathletes may reflect continued skill enhancement over the training period.

Differential effects of stimulation frequency on isometric and concentric isotonic contractile function in human quadriceps.

Electrically evoked contractions are used to assess the relationship between frequency input and contractile output to characterize inherent muscle function, and these have been done mostly with isometric contractions (i.e., no joint rotation). The purpose was to compare the electrically stimulated frequency and contractile function relationship during isometric (i.e., torque) with isotonic (i.e., concentric torque, angular velocity, and mechanical power) contractions. The knee extensors of 16 (5 female) young recreationally active participants were stimulated (∼1-2.5 s) at 14 frequencies from 1 to 100 Hz. This was done during four conditions, which were isometric and isotonic at loads of 0 (unloaded), 7.5%, and 15% isometric maximal voluntary contraction (MVC), and repeated on separate days. Comparisons across contractile parameters were made as a % of 100 Hz. Independent of the load, the mechanical power-frequency relationship was rightward shifted compared with isometric torque-frequency, concentric torque-frequency, and velocity-frequency relationships (all P ≤ 0.04). With increasing load (0%-15% MVC), the isotonic concentric torque-frequency relationship was shifted leftward systematically from 15 to 30 Hz (all P ≤ 0.04). Conversely, the same changes in load caused a rightward shift in the velocity-frequency relationship from 1 to 40 Hz (all P ≤ 0.03). Velocity was leftward shifted of concentric torque in the unloaded isotonic condition from 10 to 25 Hz (all P ≤ 0.03), but concentric torque was leftward shifted of velocity at 15% MVC isotonic condition from 10 to 50 Hz (all P ≤ 0.03). Therefore, isometric torque is not a surrogate to evaluate dynamic contractile function. Interpretations of evoked contractile function differ depending on contraction type, load, and frequency, which should be considered relative to the specific task.NEW & NOTEWORTHY In whole human muscle, we showed that the electrically stimulated power-frequency relationship was rightward shifted of the stimulated isometric torque-frequency relationship independent of isotonic load, indicating that higher stimulation frequencies are needed to achieve tetanus. Therefore, interpretations of evoked contractile function differ depending on contraction type (isometric vs. dynamic), load, and frequency. And thus, isometric measures may not be appropriate as a surrogate assessment when evaluating dynamic isotonic contractile function.

The relationship between muscle thickness and pennation angle is mediated by fascicle length in the muscles of the lower extremities.

Muscle morphological architecture, a crucial determinant of muscle function, has fascinated researchers since the Renaissance. Imaging techniques enable the assessment of parameters such as muscle thickness (MT), pennation angle (PA), and fascicle length (FL), which may vary with growth, sex, and physical activity. Despite known interrelationships, robust mathematical models like causal mediation analysis have not been extensively applied to large population samples. We recruited 109 males and females, measuring knee flexor and extensor, and plantar flexor MT, PA, and FL using real-time ultrasound imaging at rest. A mixed-effects model explored sex, leg (dominant vs. non-dominant), and muscle region differences. Males exhibited greater MT in all muscles (0.1 to 2.1 cm, p < 0.01), with no sex differences in FL. Dominant legs showed greater rectus femoris (RF) MT (0.1 cm, p = 0.01) and PA (1.5°, p = 0.01), while vastus lateralis (VL) had greater FL (1.2 cm, p < 0.001) and PA (0.6°, p = 0.02). Regional differences were observed in VL, RF, and biceps femoris long head (BFlh). Causal mediation analyses highlighted MT's influence on PA, mediated by FL. Moderated mediation occurred in BFlh, with FL differences. Gastrocnemius medialis and lateralis exhibited FL-mediated MT and PA relationships. This study unveils the intricate interplay of MT, FL, and PA in muscle architecture.

Relationship between quadriceps muscle architecture and lower limb strength and physical function in older adults community-dwelling individuals: a cross-sectional study.

Background and objective: Factors related to muscle architecture may lead to functional limitations in activities of daily living in the older adults. This study aimed to investigate the relationship between quadriceps femoris (QF) architecture and physical function in older adults community-dwelling people. Methods: The study included 25 community-dwelling older adults participants aged over 60 years (14 women and 11 men) who were not engaged in regular physical activity. The rectus femoris (RF) and vastus intermedius (VI) muscle thicknesses as well as the RF cross-sectional area (CSA) were assessed using 2D ultrasonography. The 30 Seconds Chair Stand test (30sCST) and Timed Up and Go Test (TUG) were used to assess lower body muscle power and functional mobility, respectively. Results: The QF muscle architecture showed moderate and large correlations with the 30sCST (r range = 0.45-0.67, p < 0.05) and TUG (r range = 0.480-0.60, p < 0.05). RF thickness was a significant (p < 0.01) independent predictor of 30sCST (R 2 = 0.45) and TUG (R 2 = 0.36). VI thickness was a significant (p < 0.05) independent predictor of 30sCST (R 2 = 0.20) and TUG (R 2 = 0.231). RF CSA was a significant independent predictor of the 30sCST (R 2 = 0.250, p < 0.05) and TUG (R 2 = 0.27, p < 0.01). Multiple linear regression models explained 38% of the 30sCST variance and 30% of the TUG variance in the older adults group. Conclusion: Quadriceps muscle group directly affects basic activities of daily living in the older adults. Ultrasound measurements, which are non-invasive tools, are extremely valuable for understanding the limitations of activities of daily living in the older adults.

Effects of Alaska Pollack Protein Ingestion on Neuromuscular Adaptation in Young Healthy Adults: A Randomized, Placebo-Controlled Trial.

Alaska pollack protein (APP), has been reported as a protein source that can enhance muscle hypertrophy more than other protein sources in animal studies. This study aimed to examine the effects of APP ingestion on muscle quantity and quality in young adults. Fifty-five young college students were assigned to two groups: APP and placebo (whey protein: WP) groups, and instructed to ingest 4.5 g of each protein in addition to daily meals, and to maintain their usual daily physical activities for 3 mo. Twenty-one and 23 students completed the intervention and were analyzed in APP and WP groups, respectively. The maximum knee extension torque significantly increased in both groups during the intervention. The motor unit discharge rate, which is an indicator of activation, for a given force level significantly decreased in both groups during the intervention, but its decrease in the APP group was significantly greater than in the WP group. Echo intensity of the vastus lateralis evaluated by ultrasound images significantly decreased in both groups. The muscle thickness and skeletal muscle mass did not change. Small amount of additional APP intake induces greater effects on neural activation than WP, suggesting the greater neural economy of generation of force.

Physical Therapists' Prognosis of Outcomes After a Hip or Quadriceps Exercise Intervention in Patients With Patellofemoral Pain: A Secondary Analysis of a Randomized Trial.

OBJECTIVE: Can physical therapists who are treating patients with patellofemoral pain (PFP) predict the outcome of a 12-week exercise intervention based on initial assessment, and what are the physical therapists' reasons for prediction? DESIGN: Secondary analysis of a randomized trial. METHODS: After the initial assessment, physical therapists were asked to predict the prognosis of 200 patients with PFP who were allocated to 12 weeks of quadriceps exercises (QEs) or hip exercises (HEs) on a 1-to-10 Likert scale, and to describe their reasoning for the prediction score. OUTCOMES: measures were changes from baseline to weeks 12 and 26 on the Anterior Knee Pain Scale (range 0-100) and a transition questionnaire (TransQ). Linear mixed-effects models were used to assess the prediction. Secondly, we used a qualitative approach to summarize the physical therapists' reasoning (written notes) when predicting the outcome. RESULTS: There was no association between physical therapists' prognosis and changes in Anterior Knee Pain Scale for QE or HE at weeks 12 and 26 (slopes: -0.14 to -0.51 with wide 95% confidence intervals). There was no association between physical therapists' assessment of prognosis using TransQ for QE or HE at weeks 12 and 26 (odds ratio: 0.99 to 1.17 with wide 95% confidence intervals). CONCLUSION: Physical therapists' prognosis based on initial assessment was not associated with outcomes after 12 weeks of either quadriceps or hip exercise therapy among patients with PFP. Physical therapists' prognoses were not useful as a source of information and to identify PFP patients with poor or good projected outcomes. J Orthop Sports Phys Ther 2024;54(8):541-550. Epub 6 June 2024. doi:10.2519/jospt.2024.12258.

Exercise responses to repeated cycle sprints with continuous and intermittent hypoxic exposure.

We examine the impact of the acute manipulation of oxygen availability during discrete phases (active and passive) of a repeated-sprint cycling protocol on performance, physiological, and perceptual responses. On separate days, twelve trained males completed four sets of five 5-s 'all out' cycle sprints (25-s inter-sprint recovery and 5-min interset rest) in four randomized conditions: normobaric hypoxia (inspired oxygen fraction of 12.9%) applied continuously (C-HYP), intermittently during only the sets of sprints (I-HYPSPRINT) or between-sets recovery periods (I-HYPRECOVERY), or not at all (C-NOR). Peak and mean power output, peripheral oxygen saturation, heart rate, blood lactate concentration, exercise-related sensations, and vastus lateralis muscle oxygenation using near-infrared spectroscopy were assessed. Peak and mean power output was ∼4%-5% lower for C-HYP compared to C-NOR (P ≤ 0.050) and I-HYPRECOVERY (P ≤ 0.027). Peripheral oxygen saturation was lower during C-HYP and I-HYPSPRINT compared with C-NOR and I-HYPRECOVERY during sets of sprints (∼83-85 vs. ∼95%-97%; P < 0.001), while lower values were obtained for C-HYP and I-HYPRECOVERY than C-NOR and I-HYPSPRINT during between-sets rest period (∼84-85 vs. ∼96%; P < 0.001). Difficulty in breathing was ∼21% higher for C-HYP than C-NOR (P = 0.050). Ratings of perceived exertion (P = 0.435), limb discomfort (P = 0.416), heart rate (P = 0.605), blood lactate concentration (P = 0.976), and muscle oxygenation-derived variables (P = 0.056 to 0.605) did not differ between conditions. In conclusion, the method of hypoxic exposure application (continuous vs. intermittent) affects mechanical performance, while internal demands remained essentially comparable during repeated cycle sprints.

Effects of Neuromuscular Electrical Stimulation on Muscle Strength, Functional Capacity, and Quality of Life Among Older Patients With Asthma.

Context: Asthma incidence in the older people also increases as the number of individuals over the age of 65 increases in society. The goals of asthma management include restoring expected levels of physical activity and preserving muscle mass as well as preventing symptoms and improving pulmonary function. A limited number of studies have explored the effects of superimposed neuromuscular electrical stimulation (NMES) on the quadriceps muscle for older patients with asthma. Objective: The study intended to investigate the effects of adding superimposed NMES to a conventional physiotherapy and rehabilitation (PTR) program for older patients with asthma. Design: The research team performed a blinded, randomized controlled trial. Setting: The study took place at the Kadikoy Municipality Social Life Center. Participants: Participants were 24 people with mild, persistent, stable asthma diagnosis. Interventions: The research team randomly divided participants into two groups: (1) an intervention group, the NMES + PTR group with 12 participants and a control group, the PTR group with 12 participants. All participants took part in a PTR program, which consisted of a conventional exercise program. Additionally, the NMES + PTR group received NMES applied to quadriceps muscle with a superimposed technique. Outcome Measures: At baseline, at four weeks, and postintervention, the research team assessed participants': (1) endurance of the quadriceps using the Sit to Stand Test (SST); (2) the muscle's strength using surface electromyography (sEMG) and a myometer; (3) functional exercise capacity using the Six-Minute Walking Test (6MWT), (4) quality of life (QoL) using the Asthma Quality of Life Questionnaire (AQOL); (5) dyspnea using the Modified Medical Research Council (MMRC) dyspnea scale; and (6) pulmonary functions using spirometry. Results: Postintervention, the NMES + PTR group's scores for the sit-to-stand test (P = .001), the right quadricep's sEMG active (P = .00), the right sEMG resistance (P = .00), the right myometer (P = .00), the left quadricep's sEMG active (P = .00), the left sEMG resistance (P = .00), the left myometer (P = .00), the 6MWT (P = .00), and the AQOL (P = .001) were significantly higher and on the MMRC (P = .00) were significantly lower than those of the PTR group. Conclusions: The addition of superimposed NMES to a recommended PTR program was an effective method of improving the quadricep muscle's endurance and strength, functional exercise capacity, and health-related QoL as well as decreasing dyspnea for older patients with mild persistent asthma.