Body Composition, Anthropometric Parameters, and Strength-Endurance Characteristics of Sport Climbers: A Systematic Review.

ABSTRACT: Ginszt, M, Saito, M, Zieba, E, Majcher, P, and Kikuchi, N. Body composition, anthropometric parameters, and strength-endurance characteristics of sport climbers: a systematic review. J Strength Cond Res 37(6): 1339-1348, 2023-Sport climbing was selected to be part of the Summer Olympic Games in Tokyo 2021 with 3 subdisciplines: lead climbing, speed climbing, and bouldering. The nature of physical effort while speed climbing, lead climbing, and bouldering performance is different. This literature review aimed to describe differences between body composition, anthropometric parameters, and upper-limb strength-endurance variables between sport climbers with different ability levels and nonclimbers. The following databases were searched: PubMed and Scopus. The following keywords were used: "sport climbing," "rock climbing," "lead climbing," and "bouldering." Articles were considered from January 2000 to October 2021 if they concerned at least one of the following parameters: body composition (mass, body mass index, body fat, lean muscle mass, bone mineral density), anthropometric parameters (height, ape index), muscle strength (MVC finger strength in half-crimp grip, MVC finger strength to body mass, handgrip strength), and muscle endurance (force time integral, pull-ups). A review shows that body mass and body fat content were lower in the sport climbers compared with controls and in elite sport climbers compared with those less advanced. Sport climbers presented higher values of MVC finger strength in half-crimp grip, MVC finger strength to body mass, handgrip strength, and force time integral parameter than control subjects. Significantly higher MVC values in half-crimp grip were observed in elite sport climbers than in advanced athletes. None of the analyzed work showed differences between sport climber groups in the ape index. The abovementioned parameters may be a key factor in elite sport climbing performance.

Genetic profile of sports climbing athletes from three different ethnicities.

This study aimed to investigate the ACTN3 R577X, ACE I/D, CKM rs8111989, and TRHR rs7832552 genotypes in climbers and controls in three ethnicities. The study consisted of 258 climbers (Japanese, n = 100; Polish, n = 128; Russian, n = 30) and 1151 controls (Japanese: n = 332, Polish: n = 635, Russian: n = 184). Genotyping results were analyzed using the TaqMan approach in Japanese and Polish subjects and HumanOmni1-Quad Bead Chips in Russian subjects. There were no significant differences in ACTN3 R577X and ACE I/D polymorphism distribution between climbers and controls in any ethnic cohort or model. The frequencies of the C allele in the CKM polymorphism and the T allele in the TRHR polymorphism were higher in climbers than in controls only in the Russian cohort (p = 0.045 and p = 0.039, respectively). The results of the meta-analysis on three cohorts showed that the frequency of XX + RX genotypes in the ACTN3 R577X polymorphism was significantly higher in climbers than that in the controls (p = 0.01). The X allele of the ACTN3 R577X polymorphism was associated with sport climbing status, as assessed using a meta-analysis of climbers across three different ethnicities.

Association between MCT1 T1470A polymorphism and climbing status in Polish and Japanese climbers.

Sport climbing will become an official event at the 2020 Tokyo Olympics; it is a popular wilderness sport among athletes and amateurs. Our previous study suggested that the T1470A polymorphism (rs1049434) of the monocarboxylate transporter 1 (MCT1) gene is associated with athletic performance and physiological phenotypes. The purpose of this study was to investigate the frequency of MCT1 T1470A polymorphism in Polish and Japanese climbers using a case-control study. Our sample consisted of 226 climbers (Japanese: n = 100, 64 male and 36 female; Polish: n = 126, 97 male and 29 female) and 1028 non-athletic controls (Japanese, n = 407; Polish = 621) who were genotyped for the MCT1 T1470A polymorphism (rs1049434) using the TaqMan SNP genotyping assay or restriction enzyme. The frequency of the TT genotype and T allele was significantly higher in climbers than in controls among the Polish subjects (genotype: p = 0.030, allele: p = 0.010); however, there were no significant differences in the genotype and allelic frequencies between the Japanese climbers and controls (genotype: p = 0.968; allele: p = 0.803). Our results suggested that the frequency of the T allele (TT+TA genotype) in the MCT1 T1470A polymorphism is over-represented in Polish climbers but not in Japanese climbers. In addition, the frequency of the T allele and TT genotype in Polish lead climbers is higher than that in controls.

ACTN3 Genotype in Professional Sport Climbers.

Ginszt, M, Michalak-Wojnowska, M, Gawda, P, Wojcierowska-Litwin, M, Korszen-Pilecka, I, Kusztelak, M, Muda, R, Filip, AA, and Majcher, P. ACTN3 genotype in professional sport climbers. J Strength Cond Res 32(5): 1311-1315, 2018-The functional RR genotype of the alpha-actinin-3 (ACTN3) gene has been reported to be associated with elite sprint/power athlete status. Although large and rapidly increasing number of studies have investigated the associations between the ACTN3 genotypes and athletic performance in various sport disciplines, there is a lack of studies on the genetic predisposition in sport climbing, which was selected to be part of the next Summer Olympic Games in Tokyo 2020 with three subdisciplines ("lead climbing," "speed climbing," and "bouldering"). The aim of the study is to determine the frequency distribution of ACTN3 genotypes and alleles in professional lead climbers and boulderers. 100 professional sport climbers from Poland, Russia, and Austria were divided into 2 equal groups: professional boulderers and professional lead climbers were involved in the study. ACTN3 allele frequencies and genotypes were compared with 100 sedentary controls. Genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism method. The percent distribution of RR genotype in the boulderers was significantly higher than in lead climbers and controls (62 vs. 26%; 33%, respectively; χ = 17.230, p = 0.0017). The frequencies of ACTN3 R allele in boulderers differed significantly from lead climbers and controls (77 vs. 51%; 58%, respectively; χ = 15.721, p = 0.0004). The proportion of the ACTN3 RR genotype is significantly higher in boulderers than in lead climbers and may be related to the specific type of predisposition to this subdiscipline.

Functional Status, Quality of Life, and Physical Activity of Senior Club Members-A Cross-Sectional Study.

This study aims to assess the functional status, quality of life, and physical activity (PA) of the elderly who are members of senior social clubs. The study included 63 participants (65-95 years old) who were members of a seniors club. The study utilized the following instruments: Barthel scale, Lawton's scale of Instrumental Activities of Daily Living (IADL), WHO Quality of Life-BREF questionnaire, author's survey questionnaire containing questions about the type of PA. Duration of membership in the senior club has a statistically significant effect on Barthel index score (F = 19.68, p < 0.001) and Lawton's IADL scale results (F = 17.59, p < 0.001). All four domains of life quality were strongly related to the duration of attendance to senior clubs. Participants who attended the senior club for more than five years were more likely to report a longer PA duration than participants who attended the senior club for less than 5 years (Chi2 = 25.84, p < 0.001). Attendance to senior social clubs has a strong positive impact on functional status, quality of life, and PA of the elderly. Moreover, our study identified numerous social-demographic factors associated with PA, quality of life, and functional status of senior club members.

The Effects of Wearing a Medical Mask on the Masticatory and Neck Muscle Activity in Healthy Young Women.

The objective of this study was to analyze the influence of wearing a medical mask on masticatory and neck muscle activity in healthy young women. We recruited 66 healthy women aged from 18 to 30 years (mean 23.6 ± 2.3 years). The temporalis anterior (TA), the superficial part of the masseter muscle (MM), the anterior bellies of the digastric muscle (DA), and the middle part of the sternocleidomastoid muscle (SCM) potentials were recorded at rest and during functional activity using an eight-channel device for surface electromyography-BioEMG IIITM. There was a statistically significant decrease in mean TA activity during medical mask measurement compared to no mask examination at rest (2.16 µV vs. 2.58 µV; p = 0.05; ES = 0.2). Significant decreases in resting RMS values were also observed during the medical mask phase in comparison to no mask examination concerning the left MM (1.75 µV vs. 2.17 µV; p = 0.01; ES = 0.3), and mean bioelectrical activity of the MM (1.81 µV vs. 2.15 µV; p = 0.02; ES = 0.2). The differences between the two conditions did not reach the assumed significance level (p > 0.05) in terms of other indices. Wearing a medical mask has a small effect on decreasing the resting potentials of the temporalis anterior and masseter muscles without changing the parameters of activity and asymmetry within the stomatognathic system.

Cervical Myofascial Pain Is Associated with an Imbalance of Masticatory Muscle Activity.

This study aimed to assess the relationship between the occurrence of cervical myofascial pain with active myofascial trigger points (MTrPs) within the upper trapezius muscle and the electromyographic asymmetry index (AsI) of masticatory muscles: temporalis anterior (TA), superficial part of the masseter muscle (MM), and anterior belly of the digastric muscle (DA). The study group comprised 100 subjects (80 women and 20 men) aged 18 to 30 years (mean 23 ± 2.6 years) reporting pain in the neck muscles, diagnosed with myofascial pain with active MTrPs only within the upper trapezius muscle. The control group comprised 60 healthy, pain-free subjects (42 women and 18 men) aged 20 to 30 years (mean 22.8 ± 2.6 years) without MTrPs in the upper trapezius muscle. The palpation measurement, based on the diagnostic criteria of Travell and Simons, was used to diagnose active MTrPs. The masticatory muscle activity was recorded using an 8-channel device for surface electromyography-BioEMG IIITM. Significant differences in electromyographic patterns between the group with MTrPs in the right side of upper trapezius muscle and the control group were observed within resting activity for the AsI TA (MTrPs: 8.64 vs. controls: -3.22; p = 0.001) and AsI MM (MTrPs: 7.05 vs. controls: -2.09; p = 0.018). Controls presented different electromyographic patterns during maximum voluntary clenching with cotton rolls between teeth within masseter muscle compared to the MTrPs group (MTrPs: 9.27 vs. controls: -0.43 vs. p = 0.041). Participants with MTrPs in the left side of upper trapezius muscle presented predomination of left-sided electromyographic patterns at rest within temporalis anterior in comparison to controls (MTrPs: -19.22 vs. controls: -3.22; p = 0.001). MTrPs within the trapezius muscle may be related to asymmetry within the masticatory muscle activity, suggesting that the presence of myofascial pain within the cervical muscles plays a role in the imbalance of the stomatognathic system. A unilateral active MTrPs within the trapezius muscle may increase the sEMG activity on the same side of the temporalis anterior and masseter muscles.

The Axial Length of the Eyeball and Bioelectrical Activity of Masticatory and Neck Muscles: A Preliminary Report.

Objective: The present study aimed to evaluate the correlation of eye length and bioelectric activity of temporalis, masseter, digastric, and sternocleidomastoid muscles in women with myopia compared to healthy women. Methods: Based on the exclusion and inclusion criteria, 42 women aged 24 years (±2 years) were eligible for the study. Two equally sized groups with myopic (n = 21) and emmetropic healthy subjects (n = 21) were formed. An electromyographic study of the examined muscles was performed in four conditions: at rest, during maximal voluntary clenching in the intercuspal position, during maximal voluntary clenching on dental cotton rollers, and during maximal mouth opening using BioEMG III (BioResearch Associates, Inc. Milwaukee, WI, USA). The IOL Master 500 (Carl Zeiss Meditec, Jena, Germany) was used to examine the eyeball length. Statistical analysis showed significant positive correlations during mouth opening in both groups with open and closed eyes. Results: A greater number of correlations between the analyzed variables was observed in emmetropic women. In almost all cases, the longer axial eye length was associated with an increase in the bioelectrical activity of the analyzed muscles. Significant correlations were most often observed within the masseter and digastric muscles during the maximum mouth opening and at rest. Conclusion: There is a relationship between the bioelectrical activity of the masticatory muscles and the axial length of the eyeball on the same side.

Is COL1A1 Gene rs1107946 Polymorphism Associated with Sport Climbing Status and Flexibility?

The purpose of this study was to compare the frequency of COL1A1 rs1107946 polymorphism between sport climbers and controls from three ethnic groups (Japanese, Polish, and Russian) and investigate the effect of the COL1A1 rs1107946 polymorphism on the age-related decrease in flexibility in the general population. Study I consisted of 1929 healthy people (controls) and 218 climbers, including Japanese, Polish, and Russian participants. The results of the meta-analysis showed that the frequency of the AC genotype was higher in climbers than in the controls (p = 0.03). Study II involved 1093 healthy Japanese individuals (435 men and 658 women). Flexibility was assessed using a sit-and-reach test. There was a tendency towards association between sit-and-reach and the COL1A1 rs1107946 polymorphism (genotype: p = 0.034; dominant: p = 0.435; recessive: p = 0.035; over-dominant: p = 0.026). In addition, there was a higher negative correlation between sit-and-reach and age in the AA + CC genotype than in the AC genotype (AA + CC: r = −0.216, p < 0.001; AC: r = −0.089, p = 0.04; interaction p = 0.037). However, none of these results survived correction for multiple testing. Further studies are warranted to investigate the association between the COL1A1 gene variation and exercise-related phenotypes.

Electromyographic Patterns of Masticatory Muscles in Relation to Active Myofascial Trigger Points of the Upper Trapezius and Temporomandibular Disorders.

The presented study aimed to analyze and compare the electromyographic patterns of masticatory muscles in subjects with active myofascial trigger points (MTrPs) within upper trapezius, patients with temporomandibular disorders (TMDs) and healthy adults. Based on the diagnostic criteria of MTrPs according to Travell & Simons and the Research Diagnostic Criteria for Temporomandibular Disorders, 167 people were qualified for the study. Subjects were divided into 3 groups: with active MTrPs in the upper trapezius, with diagnosed temporomandibular disorders (TMDs) and healthy adults. Measurements of the bioelectric activity of the temporalis anterior (TA) and masseter muscle (MM) were carried out using the BioEMG III ™. Based on statistical analysis, significantly lower values of TA resting activity were observed among controls in comparison to MTrPs (1.49 µV vs. 2.81 µV, p = 0.00) and TMDs (1.49 µV vs. 2.97 µV, p = 0.01). The POC index values at rest differed significantly between MTrPs and TMDs (86.61% vs. 105%, p = 0.04). Controls presented different electromyographic patterns within AcI in comparison to both MTrPs (4.90 vs. -15.51, p = 0.00) and TMDs (4.90 vs. -16.49, p = 0.00). During clenching, the difference between MTrPs and TMDs was observed within MVC TA (91.82% vs. 116.98%, p = 0.02). TMDs showed differences within AcI in comparison to both MTrPs group (-42.52 vs. 20.42, p = 0.01) and controls (-42.52 vs. 3.07, p = 0.00). During maximum mouth opening, differences between MTrPs and TMDs were observed within the bioelectric activity of masseter muscle (16.45 µV vs. 10.73 µV, p = 0.01), AsI MM (0.67 vs. 11.12, p = 0.04) and AcI (13.04 vs. -3.89, p = 0.01). Both the presence of MTrPs in the upper trapezius and TMDs are related to changes in electromyographic patterns of masticatory muscles.

Neurodevelopmental outcome and early rehabilitation of premature babies - is it needed in the first 2 years of life?

INTRODUCTION AND OBJECTIVE: The aim of the study was to evaluate the neurodevelopmental outcomes of extremely premature babies at the age of 2 years, and to determine whether rehabilitation was carried out during this period. An additional aim was to determine the relationship between the use of rehabilitation and the degree of prematurity, asphyxia, birth weight, and the result of brain ultrasound. MATERIAL AND METHODS: The study included 87 premature babies born between 24-31 weeks of pregnancy. A rehabilitation specialist assessed the neurodevelopmental outcomes of the children aged 2 years. Based on the documentation, the frequency of rehabilitation and its dependence on prematurity, asphyxia, birth weight and ultrasound results were analyzed. RESULTS: Correct neurodevelopmental outcome in children aged 2 years was found in 57 (65%) children, of whom 40 (46%) did not undergo rehabilitation. Incorrect development was observed in a group of 30 children - 12 patients were diagnosed with CP (14%), and 18 (21%) had 'red flags' of development milestones, they underwent rehabilitation. There was no statistically significant relationship between the degree of prematurity, perinatal asphyxia, birth weight and rehabilitation in the first 2 years of life. Abnormal ultrasound results were more common in rehabilitated children (n = 25; 53%) than in children without rehabilitation (n = 10; 25%), p = 0.008. CONCLUSIONS: Correct neurodevelopmental outcome at the age of 2 reached two-thirds of extreme prematurities, most of which did not need rehabilitation during this period. According to the authors' knowledge, this is the first study to show the percentage of premature babies who in the first 2 years of life did not require rehabilitation and achieved normal development.

The predictive value of 'red flags' as milestones of psychomotor development of premature babies - preliminary study.

INTRODUCTION: Premature babies are a special group at risk of persistent brain damage caused by diseases, the most serious of which are cerebral palsy(CP), autism spectrum disorders (ASD) and mental retardation, among others. These conditions may occur concurrently, but appear more often as separate disease syndromes in the same group of at-risk children. Long-term observation of psychomotor development by an interdisciplinary medical team closely cooperating with parents is necessary. It is important to detect the risk of developing these diseases as soon as possible in all development spheres. MATERIAL AND METHODS: The research was conducted to demonstrate the prognostic value of 'red flags' of developmental milestones and the ability to detect early signs of risk of developing CP and ASD in extremely premature babies. In this preliminary study, 42 preterm babies, born after less than 32 weeks pregnancy participated. RESULTS: The occurrence of 'red flags'in the spheres: gross motor, fine motor and cognitive at 9 months was strongly associated with their presence at 24 months. The sensitivity and specificity were: gross motor - 0.91 (95% CI: 0.59, 1.00) and 0.94 (95% CI: 0.79, 0.99); fine motor - 0.83 (95% CI 0.36-1.00) and 1.00 (95% CI: 0.90-1.00); cognitive - 1.00 (0.40, 1.00) and 0.97 (0.86, 1.00). Other spheres had lower sensitivity but high specificity. CONCLUSIONS: The conclusion is that the 'red flags'at the 9 months milestones already predict the normal or developmental delay of premature babies, and predict the risk of CP and ASD. Due to the availability and lack of the need for specialized and costly training, it is worth considering their use in everyday life medical practice.

The Relationship between Stress and Masticatory Muscle Activity in Female Students.

The aim of the study was to analyze the relationship between stress measured by the perceived stress scale (PSS-10) questionnaire and masticatory muscle activity. Experimental design assumed the study of healthy young women without temporomandibular disorders, dividing them into three groups depending on the result of the stress level and then comparing these groups in terms of bioelectrical activity of the masticatory muscles. After the exclusion criteria were applied, 63 female students (mean age: 22.3 ± 2.4 years) from Medical University of Lublin were included in the study. The subjects were then divided into 3 groups: with low (n = 18), medium (n = 18) and high stress level (n = 27), according to PSS-10 results. Resting and functional activity of temporalis anterior (TA) and masseter (MM) muscles were measured by electromyograph BioEMG III. There were statistically significant effects of group on the absolute value of asymmetry index (AsI) of TA and MM during maximum voluntary clenching on dental cotton rollers (both p = 0.02). Post hoc analysis shows that there were statistically significant differences between medium and high stress groups in AsI TA (p = 0.01) and between low and high stress groups in AsI MM (p = 0.02). Perceived stress measured by PSS-10 questionnaire seems to be associated with changes in muscular asymmetry in functional clenching activity.

An Interdisciplinary Model of Treatment of Children with Cerebral Palsy in Poland. Recommendations of the Paediatric Rehabilitation Section of the Polish Rehabilitation Society.

Medical rehabilitation plays an important leading role in the treatment of children with cerebral palsy (CP). Collaboration between specialists in medical rehabilitation and the rehabilitation team is a prerequisite for good medical care. The quality of medical services for children with CP depends chiefly on the level of expertise of the treatment team. Through training of specialists and sharing of knowledge, we can help more patients. This idea was developed and implemented by Dr Ewa Kooyman-Piskorz, the founder and president of Wandafonds Foundation. Between 2003 and 2014, Dutch specialists working with children with CP conducted a number of training workshops in Poland under the supervision of the Polish Rehabilitation Society and Prof. Jules Becher, a world-famous expert in the rehabilitation of children. Based on these experiences, we present the recommendations of the Paediatric Rehabilitation Section of the Polish Rehabilitation Society regarding an interdisciplinary model of treatment of children with CP in Poland.

Masticatory Muscles Activity in Sport Climbers.

Masticatory muscle activity during teeth clenching is associated with changes in many physiological parameters throughout the body. Clenching can improve muscle activity, force production, rate of force development, and joint fixation. Hence, teeth clenching and masticatory muscle activity can be important in competitive sports activities. Sport climbing is becoming increasingly popular and will be included for the first time in the Summer Olympic Games, Tokyo, 2020. However, masticatory muscle activity in sport climbers has not yet been studied. The aim of the presented study is to compare the bioelectrical activity of the masticatory muscles in sport climbers and non-climbers in order to determine the relationship between these muscles and climbing activity. 44 subjects without masticatory system disorders (16 women and 28 men, average age 26.3) were divided into two groups of 22 sport climbers (8 women, 14 men, climbing experience >4 years), while 22 people (8 women, 14 men, with no regular sports activity) were assigned to the control group. Electromyographic examination of temporalis anterior (TA) and masseter muscle (MM) was evaluated in three conditions: during resting mandibular position, during maximum intercuspation clenching, and during maximum voluntary clenching with cotton rolls between teeth. For statistical analysis, the W Shapiro-Wilk test and the Mann-Whitney U test were used. Sport climbers showed significantly higher bioelectrical activities of MM during maximum intercuspation clenching (238.45 µV vs. 83.87 µV, p = 0.002), and during maximum voluntary clenching with cotton rolls between teeth (300.01 µV vs. 101.38 µV, p = 0.001) compared to controls. The differences between groups in relation to the resting bioelectrical activity of the MM muscles, and TA muscles in all conditions were not statistically significant (p > 0.05). Higher bioelectrical activity of masseter muscles during clenching in climbers can be associated with this sports activity. However, the mechanism remains unknown and requires future research.

Depression and Resting Masticatory Muscle Activity.

BACKGROUND: The aim of this study was to determine the influence of moderate depression determined based on Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMDs) Axis II on the bioelectrical resting activity of temporal muscles and masseter muscles. METHODS: The research participants were 68 healthy adult women. Of these, 46 people h (mean age: 22 ± 1 year) who had no temporomandibular disorders were selected for the research. They were divided based on results from RDC/TMDs (Axis II: scale's measurement) into the study group with a moderate level of depression (23 people), rest of participants without symptoms of depression were classified to control group (23 people). The resting activity of temporal muscles and masseter muscles was examined by using BioEMGIII electromyograph. Two statistical analyses were used: Shapiro-Wilk test and Mann-Whitney U test. RESULTS: Despite higher mean tensions of temporal muscles and masseter muscles in the group with depression, results findings were not statistically significant (p > 0.05). CONCLUSIONS: Moderate depression determined based on the RDC/TMDs II axis questionnaire is not related to the resting activity of selected masticatory muscles. Further research should be continued on a larger group of respondents in order to establish the relationship between psychological factors and bioelectrical parameters of the masticatory muscles.

Observation using thermography of post-operative reaction after fascial manipulation®.

INTRODUCTION AND OBJECTIVE: Fascia Manipulation® is one of the methods focusing on the deep fascia. The assumption is that fascial manipulation is carried out on precisely determined points - coordination centres (cc), and on a limited area so as the friction occurring during manipulation would cause a local rise in temperature due to the inflammatory reaction. Rise in temperature influences modification in consistency of elementary matter in the manipulated area, and by the same token causing a decrease in the negative effects of fascia densification which stems from accumulation of hyaluronic acid. The purpose of the research is to prove the thesis that fascial manipulation causes local rise in temperature due to inflammatory reaction. MATERIAL AND METHODS: For the research, 25 individuals with densification in lower limb area were qualified. They were exposed to a single, 3-minute facial manipulation®. By means of a thermal-imaging camera, changes in the temperature of the body in the examined area were evaluated. The body's temperature evaluation was carried out 8 times: before the treatment, 5 minutes after the treatment, and, next, 6, 12, 18, 24, 36, 48 hours after the treatment. RESULTS: The average surface temperature of the treated area before mobilization was 33.4°C. A statistically relevant increase in temperature was already observed 5 minutes after the treatment (increase of 0.5°C; p<0.001). However, the highest temperature was observed 24 hours after mobilization (increase of 2.4°C). The difference between the first and 7 other measurements was statistically relevant (p<0.001). CONCLUSIONS: The statistically relevant increase in temperature under the influence of fascial manipulation® in the treatment area can confirm the occurrence of inflammatory reaction.

Bioelectrical Activity of Vastus Medialis and Rectus Femoris Muscles in Recreational Runners with Anterior Knee Pain.

Patellofemoral pain syndrome (PFPS), the most common source of knee pain among physically active individuals, is defined as anterior knee pain involving the patella and retinaculum that excludes other intraarticular and peri-patellar pathology. Differences in the activation and endurance of the quadriceps components, causing an imbalance in the forces controlling patellar tracking during flexion and extension in the knee joint, appear to be the most commonly reported risk factors for PFPS. The aim of this study was to determine the differences in bioelectric activity of vastus medialis and rectus femoris muscles during half knee bend position in runners with PFPS. The sample comprised 20 recreational runners (15 males, 5 females; aged 27 ± 5 years) reporting knee pain and diagnosed with PFPS. The age- and sex-matched control group consisted of recreational runners who did not report knee pain. The myon electromyographic system was used to determine the changes in the electromyographic median frequency during a half squat position. The decrease in the median frequency of vastus medialis and rectus femoris muscles was significantly greater in runners with PFPS in comparison to the control group (p < 0.01 for right and left vastus medialis and right rectus femoris; p < 0.05 for left rectus femoris). There is a relationship between knee pain related to PFPS and the imbalance of bioelectric activity of vastus medialis and rectus femoris muscles. Achieving the muscular balance within the thigh muscles can be an important factor in the rehabilitation process of PFPS.

Differences in myoelectric manifestations of fatigue during isometric muscle actions.

INTRODUCTION: Muscle fatigue has been studied for a long time with the use of a wide variety of exercise models, protocols and assessment methods, among which surface electromyography (sEMG) is most commonly used. The main sEMG parameters (amplitude and frequency) are prevalently used to evaluate the level of muscle fatigue in static and dynamic contractions. OBJECTIVE: The purpose of this study is to determine and compare 2 separate indices: IF1 basis of the sEMG signal amplitude analysis and IF2 basis of the sEMG median frequency analysis, related to muscles fatigue during an isometric contraction. MATERIAL AND METHODS: The study was performed on 60 professional runners divided into 2 equal groups. The first group comprised sprinters, competing in short distance track and field events (100 and 200 meters). The second group consisted of middle-distance runners, competing in middle-distance track and field events (800 and 1,500 meters). The electrical activity of the VMO muscles of the right and left lower limbs was recorded simultaneously during isometric activity in a squatting position. The sEMG data was used to determine and compare IF1 and IF2 indices. RESULTS: During isometric measurement, sprinters presented a much more significant increase in the mean amplitude of sEMG signal in comparison to middle-distance runners (mean IF1 difference: 0.228; p=0.007). Analysis of the median frequency did not show significant differences between the 2 groups (mean IF2 difference: 0.037; p=0.12). CONCLUSIONS: Change in sEMG amplitude during isometric exercise may be related to muscles fatigue. The use of fatigue indices, based on sEMG amplitude, as an objective indicator of the efficacy of an endurance training programme for sportsmen requires further research.

Bioelectric activity of mastication muscles and the functional impairment risk groups concerning the masticatory muscles.

PURPOSE: Temporomandibular disorders affect from 5 to 12 percent of the population, occurring almost twice as often in women than in men. The painful form of temporomandibular disorders is one of the most common musculoskeletal disorders causing pain. The chronic form is associated with changes in activity of the masticatory muscles and can lead to sleep problems, reduction of emotional state and worsening of quality of life. METHODS: 66 women were included in the study group. The study was composed of a clinical evaluation of temporomandibular disorders and assessment of the masticatory muscle activities using surface electromyography. The anterior part of the temporalis muscle and the superficial part of the masseter muscle were evaluated during teeth clenching on cotton rolls. The symmetric activity index was calculated from the results of electromyographic activity. Based on the activity and symmetric activity index values, subjects were qualified to the risk group of temporomandibular disorders. RESULTS: Twenty people (30.3 percent) qualified for the temporomandibular disorders risk group. In the temporomandibular disorders risk group, the mean symmetric activity index value of the anterior part of the temporal muscle was 72.6 percent and the mean electromyographic activity was 143.94 microvolts. In the masseter muscle, the mean symmetric activity index value was 67.7 percent and the mean electromyographic activity was 155.33 microvolts. CONCLUSIONS: Temporomandibular disorders may develop in 30.3 percent of examined women. The research should be continued to determine the temporomandibular disorders risk group, which may enable for the appropriate prevention of the development of dysfunctions in the stomatognathic system.