Search Results (52)

Background/Objectives: The ability to maintain movement quality despite muscle fatigue is essential for daily activities and preserving independence after motor impairments. Many real-life situations involve asymmetrical muscle activation, leading to unilateral muscle fatigue. Repeated unilateral handgrip contractions at submaximal force have been linked to neural changes in both contralateral and ipsilateral motor areas, as well as improved contralateral response times in a button-press task. However, it remains unclear whether these improvements in response latency extend to higher-level benefits in overall arm movement quality. Methods: Thirty healthy participants performed unilateral handgrip fatiguing tasks at 5%, 50%, and 75% of maximum voluntary contraction (MVC) force. Subsequently, bilateral upper-limb movement quality was assessed in an object-hit task using a Kinarm robot. Results: The 50% and 75% MVC protocols elicited muscle fatigue as evidenced by declines in force output, post-exercise MVC, electromyography magnitude changes, and increased perceived exertion compared to the 5% MVC control condition. However, no significant changes in kinematic measures of the object-hit task were observed for either the fatigued (ipsilateral) or non-fatigued (contralateral) arm, indicating that unilateral handgrip fatigue did not affect higher-level movement quality. Conclusions: Previously reported improvements on contralateral response latency in a button-press task were not found to translate into advanced arm movement quality benefits. Full article

Background: Age-related declines in skeletal muscle quality and quantity contribute to frailty and sarcopenia, leading to physical dysfunction in older adults. In particular, the selective atrophy of fast-twitch fibers is closely linked to reduced lower limb strength and increased fall risk. This study aimed to evaluate the effects of habitual body weight resistance training on muscle fiber recruitment patterns during maximal voluntary contraction (MVC) and squatting movements using spectral characteristics of surface electromyography (EMG). Methods: Fifty healthy community-dwelling older adults (28 males, 22 females; aged 64–84 years) were categorized into exercise and non-exercise groups based on training habits. Surface EMG signals were recorded from the rectus femoris muscle during MVC, normal squat, half-squat, and squat movements. Power spectral density (PSD) was analyzed using Welch’s method and divided into frequency bands: type I (20–60 Hz), type IIa(1) (60–115 Hz), type IIa(2) (115–170 Hz), and type IIx (170–350 Hz). Results: While statistical significance was limited, the exercise group tended to show higher ratio PSDs in type IIa and IIx bands, and lower PSDs in the type I band during MVC. During half-squats, the non-exercise group exhibited higher contributions above 60 Hz, suggesting inefficient fast-twitch fiber recruitment. Conclusions: Habitual body weight resistance training may influence muscle fiber recruitment patterns in older adults. EMG spectral analysis offers a non-invasive means to detect age- and training-related neuromuscular adaptations. Full article

Background: Cryocompression, an emerging therapy combining cryotherapy and compression therapy, has limited evidence regarding its effects on recovery from exercise-induced muscle damage. Methods: This study aimed to compare the effects of cryotherapy (CT), normothermic water compression (NWC), and cryocompression (CC) on muscle damage, proprioception, and performance following eccentric exercise. Forty healthy male participants performed 30 sets of 10 maximal isokinetic eccentric contractions (30°/s) of the quadriceps of the non-dominant leg. Muscle damage indicators [thigh circumference (CIR), muscle soreness measured by visual analog scale (VAS)], proprioception [position sense (PS), force sense (FS)], and performance parameters [range of motion (ROM), maximal voluntary isometric contraction (MVIC)] were assessed before and on days 1–5 following eccentric exercise. Two-way repeated-measures ANOVA with Tukey’s post hoc tests was used to evaluate group × time interactions. Results: Significant interactions were observed for CIR between the CT, NWC and CC groups compared to the control group, as well as for VAS scores between the CC and CON groups (p < 0.05). No other outcome measures showed significant interactions (p > 0.05). The control group showed a peak CIR increase of ~6.6 mm (day 3) versus 2.4 mm (CT), 3.6 mm (NWC), and 2.1 mm (CC). By day 5, the control group remained elevated at 5.2 mm, while CT returned to baseline by day 4. NWC and CC groups showed no significant changes on days 1–5. VAS scores in the CON group peaked at ~77 mm on day 2, not returning by day 5, whereas the CC group reached 48 mm and returned to baseline by day 3. Conclusion: Cryocompression reduced limb swelling and muscle soreness, as well as post-exercise-induced muscle damage, and NWC mitigated limb swelling, but none significantly affected proprioception or performance parameters. Full article

Background/Objectives: In recent years, scientific literature has illustrated the growing interest in telerehabilitation after ACL reconstruction. The aim of this study is to compare the effectiveness of remotely supervised rehabilitation with traditional supervised rehabilitation after ACLR, focusing on objective postoperative functional assessment outcomes. Methods: A retrospective analysis of prospectively collected data was carried out, selecting patients that underwent arthroscopic ACLR by a single surgeon. Functional assessments of the patients were carried out at 1 and 2 weeks and 1, 2 and 3 months after surgery, including range of motion (ROM), maximal voluntary isometric contractions (MVICs) of extensor and flexor muscles, the sit-to-stand test and the countermovement jump. Intergroup statistics were carried out using a non-inferiority hypothesis. Results: A total of 251 patients were included in this study (supervised rehabilitation n = 165; remotely supervised rehabilitation n = 86). Functional assessment improved over time in both groups. The extension ROM deficit decreased to 0 difference 30 days after surgery. The median flexion ROM ILD at 60 days was significantly different among the groups, with a residual 10° ILD in the Group R compared with 0° ILD in group S (p = 0.01). All other assessments did not achieve statistical significance. Conclusions: The results support the integration of a digital rehabilitation tool in post-ACLR recovery programs. The results suggest that remotely supervised rehabilitation can be a viable alternative to traditional supervised rehabilitation for early-stage recovery. However, more research is needed to optimize protocols and to identify patients who may benefit most from this approach. Full article

Background: Sarcopenia (loss of muscle mass) and dynapenia (loss of strength) are prevalent in older adults aged 70 years and over. Both have an impact on their functional ability and quality of life, with type II muscle fibres being particularly affected. Although traditional resistance training (TRT) is effective, it presents technical difficulties and an increased risk of injury among this vulnerable population. Isometric strength training (IST) is a potentially safer, more accessible and more effective alternative. Objective: To describe the protocol of a single-arm, pre-post intervention trial designed to evaluate the efficacy and applicability of a 16-week IST programme on muscle strength, skeletal muscle mass, quality of life and applicability (safety, acceptability, perceived difficulty) in 18 older adults aged 70 years and above with a diagnosis of sarcopenia and dynapenia. The influence of genetic and environmental factors on the variability of response to IST will also be explored. Methodology: The participants, who have all been diagnosed with sarcopenia according to EWGSOP2 (European Working Group on Sarcopenia in Older People 2) criteria, will perform two IST sessions per week for 16 weeks. Each 30-min session will consist of one progressive set (total duration 45 s to 90 s) for each of the eight major muscle groups. This series will include phases at 20% and 40% of individual Maximal Voluntary Isometric Contraction (MVIC), culminating in 100% Maximal Effort (ME), using the CIEX SYSTEM machine with visual feedback. The primary outcome variables will be: change in knee extensor MVIC and change in Appendicular Skeletal Muscle Mass Index (ASMMI). Secondary variables will be measured (other components of sarcopenia, quality of life by EQ-5D-5L, use of Likert scales, posture and physiological variables), and saliva samples will be collected for exploratory genetic analyses. The main statistical analyses will be performed with t-tests for related samples or their non-parametric analogues. Discussion: This protocol details a specific IST intervention and a comprehensive evaluation plan. The results are expected to provide evidence on the feasibility and effects of IST among older adults with sarcopenia and dynapenia. Understanding individual variability in response, including genetic influence, could inform the design of more personalised and effective exercise strategies for this population in the future. Full article

Background: Lower limb motor output contributes to determining functional performance in many motor tasks. This study investigated the effects of non-invasive spinal cord transcutaneous stimulation (scTS) applied during an exercise-based priming protocol on lower limb muscle force and power generation. Methods: Twelve young, physically active male volunteers (age: 22.7 ± 2.1 years) participated in this randomized crossover, sham-controlled study. The maximal voluntary contraction and low-level torque steadiness of knee extensors, as well as the maximal explosive extension of lower limbs, were assessed before and after the priming protocol with scTS or sham stimulation over a total of four experimental sessions. Further, characteristics of evoked potentials to scTS related to spinal circuitry excitability were assessed in the supine position before and after the scTS priming protocol. The exercise component of the ~25 min priming protocol consisted of low-volume, low- and high-intensity lower limb motor tasks. Results: scTS priming protocol tended to increase or maintain maximum isometric torque during knee extension (4.7%) as well as peak force (0.2%) and rate of force development (6.0%) during explosive lower limb extensions, whereas sham priming protocol tended to decrease them (−4.3%, −3.3%, and −15.1%, respectively). This resulted in significant interactions (p = 0.001 to 0.018) and medium–large differences between scTS and sham protocols. These findings were associated with meaningful trends of some neurophysiological variables. Conversely, priming protocols did not affect low-level torque steadiness. Conclusions: scTS counteracted the unexpected fatigue induced by the exercise-based priming protocol, supporting lower limb performance during maximal efforts. Future studies are warranted to assess the implementation of scTS with optimized exercise-based priming protocols during training and rehabilitation programmes that include high-intensity neuromuscular efforts. Full article

Introduction: Spinal and bulbar muscular atrophy (SBMA) is an adult-onset, X-linked, progressive neuromuscular disease caused by abnormal CAG trinucleotide expansion in the androgen receptor gene. Patients with SBMA report difficulty with falls on self-reported activities of daily living scales. To our knowledge, no study has examined the relationship between falls and common clinical measures of strength, balance, mobility, and disease biomarkers. We performed a cross-sectional analysis of an SBMA cohort. Objectives: The objectives of this study are as follows: (1) compare demographics, clinical measures, and biomarkers between patients who did and did not fall; (2) determine which measures best discriminate fallers from non-fallers; and (3) identify cutoff scores to detect patients with a higher fall risk. Design: Cross-sectional analysis was used. Outcome Measures: Disease biomarkers included blood serum creatinine, and clinical measures included the Timed Up and Go (TUG), the Adult Myopathy Assessment Tool (AMAT), and posturography, including the Modified Clinical Test of Sensory Interaction on Balance and the Motor Control Test. The Maximal Voluntary Isometric Contractions (MVICs) of four lower extremity muscles were captured via fixed-frame dynamometry. Results: We identified three clinical measures that help detect fall risk in people with SBMA. A post hoc receiver operating characteristic curve analysis helped identify cut scores for each test. Impairments of mobility (TUG > 8 s), muscle endurance (AMAT endurance subscale < 14), and muscle strength (ankle plantar flexion MVIC < 45% of predicted) were different between fallers and non-fallers, via independent t-tests. Conclusions: These three clinical tests can help detect fall risk that may help clinicians implement gait aid use or other fall prevention strategies before catastrophic falls occur. Full article

Background: Pelvic floor muscle (PFM) dysfunctions, such as urinary incontinence (UI), significantly impact women’s quality of life. The abdominal hypopressive technique (AHT), a breathing and posture-based intervention, has emerged as a promising approach to improve PFM function. Despite growing evidence on its efficacy, limited research explores its effect on PFM contractility. Objective: This study aimed to evaluate the effects of an 8-week AHT program on pelvic floor muscle (PFM) strength in adult women with no prior experience with AHT. Methods: A randomized controlled trial was conducted with 42 females (mean age 43 ± 9 years) assigned to an experimental group (EG, n = 21) or a control group (CG, n = 21). The EG completed 24 AHT sessions (30 min/session, 3 sessions/week) over 8 weeks. PFM strength, measured via maximum voluntary contraction (MVC), was assessed pre- and post-intervention using the Phenix Biofeedback Kit. Secondary outcomes included load absorption and muscle efficiency. Muscle efficiency and load absorption were also registered. Results: After the 8-week intervention, significant improvements were observed in the EG for maximal voluntary contraction (MVC1 (from 672.2 ± 344.1 g/cm² to 890.3 ± 435.8 g/cm², p = 0.002) and load absorption (from 83.9 ± 36.8 to 103.1 ± 37.3, p = 0.001), with no significant changes in the CG. Between-group differences for MVC1 (p = 0.001), MVC2 (p = 0.016), and load absorption (p = 0.008) were statistically significant. High adherence (96%) and no adverse events were recorded. Conclusions: An 8-week AHT program significantly improved PFM strength, load absorption, and muscle efficiency in women from the present study comparing with the CG. AHT could be considered a safe, non-invasive, and effective intervention for pelvic floor rehabilitation, with potential benefits for addressing UI and enhancing pelvic floor functionality. Future research should focus on long-term outcomes and comparisons with alternative therapies. Full article

The aim of this research was to investigate the effects of primarily asymmetrical (soccer and volleyball) and symmetrical sport load (sprint and swimming) in the upper and lower limbs on dynamic balance and muscle strength and to compare these values in the dominant and non-dominant limbs. This study employed a cross-sectional design, included 45 adolescent female athletes from four sports, divided into asymmetric (ASYM, n = 25) and symmetric (SYM, n = 20) groups. They were assessed for maximal voluntary isometric muscle contraction (MVIC) relative muscular strength using a handheld dynamometer (HHD) for shoulder external rotation (ER) and internal rotation (IR), as well as hamstring and quadricep strength. Upper and lower limb balance were also assessed using the Upper (YBT-UQ) and Lower Quarter Y Balance Test (YBT-LQ) tests. The results showed significantly greater balance in the upper extremities of swimmers and in the lower extremities of the sprinters in both the dominant (DS) and non-dominant (NDS) sides than in other groups (p < 0.0001). However, no significant difference in internal and external shoulder rotator muscles strength between the groups (p > 0.05). Although significant differences were found in hamstring strength on the dominant side and quadricep strength on both sides (p < 0.05), a notable finding was that sprint athletes consistently demonstrated stronger quadriceps muscles as compared to other groups in both the dominant and non-dominant sides. According to the current findings, there are significant differences in upper and lower body balance, hamstring, and quadricep muscle strength among sports. This suggests that athletes of asymmetrical sports may need to improve non-dominant side knee strength and balance symmetry to prevent the risk of injury. Full article

Background/Objectives: The active straight leg raise requires intricate coordination between the hip, knee, pelvis, and spine. Despite its complexity, limited research has explored the relationship between lower limb raising velocity and trunk muscle motor control during an active straight leg raise in healthy individuals. This study aimed to explore the potential effects of increased lower limb raising velocity on core muscle contractions during active straight leg raises. Methods: Six healthy adult men (mean age: 24.5 ± 2.5 years) participated in this study. Electromyography signals were recorded using surface electrodes placed on the rectus abdominis, external oblique, and internal oblique/transverse abdominis muscles. The participants performed active straight leg raises at three different velocities: 3 s, 2 s, and as fast as possible (max). The electromyography data were analyzed from 250 ms before to 1000 ms after movement initiation, with muscle activity expressed as a percentage of the maximal voluntary isometric contraction. Statistical analyses were conducted using non-parametric tests, including the Friedman test for overall differences, followed by pairwise Wilcoxon signed-rank tests with Bonferroni correction for multiple comparisons (p < 0.05). Results: During the 250 ms before movement initiation, the internal oblique/transverse abdominis, external oblique, and rectus abdominis muscles showed greater activity in the max condition compared to the 3 s and 2 s conditions (Friedman test, p < 0.05), but no significant differences were found in pairwise comparisons (Wilcoxon test, p > 0.05). Similarly, during the 500 ms after movement initiation, internal oblique/transverse abdominis activity was higher in the max condition, with no significant pairwise differences observed. Conclusions: Faster lower limb raising velocities during active straight leg raise may enhance core stability by activating anticipatory and sustained internal oblique/transverse abdominis, external oblique, and rectus abdominis activity on the raised limb side. Training to promote this activation could improve dynamic stability in rapid or asymmetric movements. Full article

Limited studies exist examining the reverse lunge. The purpose of this study was to describe the activation of the rectus femoris (RF), biceps femoris (BF), gluteus medius (GMed), and gluteus maximus (GMax) of both limbs during a bodyweight reverse lunge movement. A secondary purpose was to describe the phases of the stationary (non-moving) and lead (moving) limbs during the reverse lunge. Surface electromyography (EMG) was used to record the activity of the target muscles in 20 healthy adults (10 male, 10 female; aged 22–25). Root mean squared values for mean maximum and average percent activation normalized to maximum voluntary isometric contraction (MVIC) activation were calculated. Descriptive terminology was created to describe the phases of the lunge for both limbs. The mean maximum percentage of muscle activation for the RF and BF was greater in the lead limb, while GMed and GMax activations were greater in the stationary limb. Only the lead limb RF and stationary limb GMed reached a strengthening stimulus in mean maximum percentage measurements. Clinically, it may be important to consider when each muscle is maximally active and at what percentage of its MVIC to properly prescribe the reverse lunge in a safe manner. Full article

Lower back pain (LBP) has been the leading cause of disability since 1990. Objectives: The main objective of this observational case–control study was to evaluate, using ultrasound, whether there were differences in the onset and ratio of core muscle contraction between subjects with non-specific chronic lower back pain and healthy subjects. Methods: A total of 60 participants (52% women), split between those with non-specific chronic lower back pain (n = 26) and healthy (n = 34) subjects, were recruited. Initial muscle contraction of the lateral abdominal wall, pelvic floor, lumbar multifidus, and respiratory diaphragm was measured using ultrasound. The abdominal drawing-in maneuver, contralateral arm elevation, the Valsalva maneuver, and voluntary contraction of the pelvic floor in seated and standing positions were performed. The muscle thickness of the lateral abdominal wall and lumbar multifidus and excursion of the pelvic floor and diaphragm at rest and during testing were also analyzed. Results: No differences were found between the groups in the initial contraction. Statistically significant differences were found in the following variables: diaphragm excursion (p = 0.032, r = 0.277) and lumbar multifidus ratio (p = 0.010, r = 0.333) in the standing–abdominal retraction maneuver; pelvic floor excursion (p = 0.012, r = 0.325) in the standing–contralateral arm raise; and transverse abdominis ratio (p = 0.033, r = 0.275) in the sitting–contralateral arm raise. A statistically significant interaction between the groups and body mass index was observed in resting diaphragm excursion (p = 0.018, partial eta squared = 0.096) during sitting–voluntary pelvic floor contraction. Conclusions: It cannot be concluded that there is a specific pattern of core activation in any of the groups. However, statistically significant differences were found in the contraction indexes of the lumbopelvic musculature. Full article

Introduction: Increases in contralateral range of motion (ROM) have been shown following acute high-intensity and high-duration static stretching (SS) with no significant change in contralateral force, power, and muscle activation. There are currently no studies comparing the effects of a high-intensity, short-duration (HISD) or low-intensity, long-duration (LILD) SS on contralateral performance. Purpose: The aim of this study was to examine how HISD and LILD SS of the dominant leg hamstrings influence contralateral limb performance. Methods: Sixteen trained participants (eight females, eight males) completed three SS interventions of the dominant leg hamstrings; (1) HISD (6 × 10 s at maximal point of discomfort), (2) LILD (6 × 30 s at initial point of discomfort), and (3) control. Dominant and non-dominant ROM, maximal voluntary isometric contraction (MVIC) forces, muscle activation (electromyography (EMG)), and unilateral CMJ and DJ heights were recorded pre-test and 1 min post-test. Results: There were no significant contralateral ROM or performance changes. Following the HISD condition, the post-test ROM for the stretched leg (110.6 ± 12.6°) exceeded the pre-test (106.0 ± 9.0°) by a small magnitude effect of 4.2% (p = 0.008, d = 0.42). With LILD, the stretched leg post-test (112.2 ± 16.5°) exceeded (2.6%, p = 0.06, d = 0.18) the pre-test ROM (109.3 ± 16.2°) by a non-significant, trivial magnitude. There were large magnitude impairments, evidenced by main effects for testing time for force, instantaneous strength, and associated EMG. A significant ROM interaction (p = 0.02) showed that with LILD, the stretched leg significantly (p = 0.05) exceeded the contralateral leg by 13.4% post-test. Conclusions: The results showing no significant increase in contralateral ROM with either HISD or LILD SS, suggesting the interventions may not have been effective in promoting crossover effects. Full article

This study investigates electromyography activation and force development differences in key lower limb muscles between female football players with previous anterior cruciate ligament injuries compared with healthy players. Twenty-two semi-professional players were divided into ACL-injured (n = 11) and non-injured groups (n = 11). Participants underwent maximal voluntary isometric contractions while electromyography activation, peak and average, and peak torque of force were measured. Results indicated significant differences in electromyography activation patterns between anterior cruciate ligament players and non-injured players, particularly in biceps femoris and gluteus maximus muscles. These differences were also evident when comparing between limbs within anterior cruciate ligament players. Interestingly, both groups exhibited similar peak torque of force during maximal contractions, suggesting a compensatory neuromuscular strategy that supports a return to sport based on kinetic and kinematic factors. However, these findings underscore persistent muscle integration imbalances potentially contributing to the high rate of anterior cruciate ligament reinjury. In conclusion, this study highlights the importance of evaluating electromyography activation alongside force development in understanding neuromuscular adaptations post anterior cruciate ligament injury. These insights emphasize the need for comprehensive rehabilitation strategies that address muscle imbalance to mitigate the risk of recurrent anterior cruciate ligament injuries in female football players. Full article

Background and Objectives: Bedridden patients are at a high risk of venous thromboembolism (VTE). Passive devices such as elastic compression stockings and intermittent pneumatic compression are common. Leg exercise apparatus (LEX) is an active device designed to prevent VTE by effectively contracting the soleus muscle and is therefore expected to be effective in preventing disuse of the lower limbs. However, few studies have been conducted on the kinematic properties of LEX. Therefore, this study aimed to compare the exercise characteristics of LEX with those of an ergometer, which is commonly used as a lower-limb exercise device, and examine its effect on the two domains of muscle activity and circulatory dynamics. Materials and Methods: This study used a crossover design in which each participant performed both exercises to evaluate the exercise characteristics of each device. Fifteen healthy adults performed exercises with LEX and an ergometer (Terasu Erugo, SDG Co., Ltd., Tokyo, Japan) for 5 min each and rested for 10 min after each exercise. Muscle activity was measured using surface electromyography (Clinical DTS, Noraxon, Scottsdale, AZ, USA), and circulatory dynamics were recorded using a non-invasive impedance cardiac output meter (Physioflow Enduro, Manatec Biomedical, Paris, France). The primary outcome was the mean percentage of maximum voluntary contraction (%MVC) of the soleus muscle during exercise. Results: The mean %MVC of the soleus muscle was significantly higher in the LEX group, whereas no significant differences were observed across the periods and sequences. Heart rate, stroke volume, and cardiac output increased during exercise and decreased thereafter; however, the differences between the devices were not significant. Conclusions: LEX may not only have a higher thromboprophylaxis effect, but also a higher effect on preventing muscle atrophy as a lower-extremity exercise device. Additionally, LEX could potentially be used safely in patients who need to be monitored for changes in circulatory dynamics. Full article