Effect of a Ten-week Sensorimotor Exercise Program on the Side-to-Side LAM Asymmetry of Adolescent Football Players: A Randomized Control Trial.

In this study we, evaluated the effects of a 10-week sensorimotor exercise program on the thickness and side-to-side asymmetry of the lateral abdominal muscles in adolescent soccer players. From among 120 initially recruited participants, we included 90 athletes (aged 10-17 years old) in our final analysis. Healthy athletes who met our inclusion criteria were randomly divided into comparative experimental and control groups. Sensorimotor exercises were conducted twice weekly for 10-weeks in the experimental group, and the control group received no intervention. We took ultrasound measurements when participants were in supine and standing rest positions. In the supine position, the experimental group (a) reduced the asymmetry of the internal oblique (IO) muscle by 0.4 mm (MD: 0.7; 95% CI 0.6-1.1); (b) increased the thickness of the external oblique (EO) muscle on the right by 0.7 mm (MD: 0.2; 95% CI 0.1-0.6) and on the left by 0.9 mm (MD: 0.2, 95% CI 0.2-0.7); and (c) increased the muscle on the IO right by 0.8 mm (MD: 0.3; 95% CI 0.2-0.9) and on the, left by 1.2 mm (MD: 0.4 95% CI 0.3-1.1). In a standing position the experimental group increased the thickness of the EO on the right by 1.5 mm (MD: 0.6; 95% CI 0.03-1.2) and on the left by 2.1 mm (MD: 0.6; 95% CI 0.1-1.3) and increased the IO on the right by 1.2 mm (MD: 0.7; 95% CI 0.2-1.7) and on the left by 1.1 mm (MD: 0.9; 95%CI 0.1-2.0). Thus, this 10-week program of additional sensorimotor exercises reduced the (side-to-side) asymmetry of the internal oblique muscle and increased the thickness of the EO and IO muscles in young football players.

Trunk muscle activation in prone plank exercises with different body tilts.

BACKGROUND: Body tilt changes could affect the intensity/difficulty of core stability exercises, but there is still a lack of knowledge about its impact. OBJECTIVE: To analyse the trunk muscles activation during prone plank exercises at different body tilts. METHODS: Twenty-four young adults who performed recreational gymnastic activities participated in this study. Electromyography activity of the rectus abdominis (RA), external oblique (EO), internal oblique (IO) and erector spinae (ES) was recorded during the performance of six variations of the prone plank exercise (planking with feet supported on the ground [conventional horizontal position] and planking with feet supported on wall bars at five different heights increasing the angle tilt) and an inverted position exercise. RESULTS: The RA, EO and IO activation in all prone plank variations were higher than those observed in the conventional prone plank. In addition, the coefficient of variation of the muscle activation increased with the declination angle, reaching the highest values in the inverted position for the RA and ES muscles. CONCLUSION: The results seem to indicate that the body tilt variation could be used as an easy and inexpensive strategy for modulating the neuromuscular demands and the motor control challenge during planking exercises.

Ultrasound Measurement of the Transverse Abdominis, Internal Oblique, and External Oblique Muscles Associated with Forward Head Posture and Reduced Cranio-Vertebral Angle.

BACKGROUND Abnormal posture can affect the alignment of the cervical spine, which can lead to various physical problems. There are many ways to solve the problem by limiting the area around the neck to restore abnormal neck condition. However, there is a need to look at these problems from an enlarged perspective through the relationship between the cervical spine and trunk. This study aimed to investigate the significance of the thickness of the transverse abdominis, internal oblique, and external oblique muscles in patients with forward head posture and reduced cranio-vertebral angle. MATERIAL AND METHODS We included 24 healthy adult males in their 20s without lower back pain. The cranio-vertebral angle (CVA) in all the subjects was measured with the help of pictures taken in the sagittal plane using a digital camera. The thickness of muscles, including transverse abdominis (TrA), internal oblique (IO), and external oblique (EO), was measured using a diagnostic ultrasound device. Pearson's correlation analysis was used to identify the correlation between the variables measured. RESULTS CVA showed a statistically significant correlation with TrA thickness (r=0.506/p=0.012), and among the abdominal muscles, there was a significant correlation between IO and EO thickness (r=0.663/p=0.000). CONCLUSIONS A reduced CVA due to FHP was significantly associated with reduced TrA thickness. Therefore, increasing the bulk of the abdominal muscles with restoration of the abnormal CVA is a potential treatment approach and requires further study.

Abdominal Muscle Use During Spontaneous Breathing and Cough in Patients Who Are Mechanically Ventilated: A Bi-center Ultrasound Study.

BACKGROUND: Ultrasound may be useful to assess the structure, activity, and function of the abdominal muscles in patients who are mechanically ventilated. RESEARCH QUESTION: Does measurement of abdominal muscle thickening on ultrasound in patients who are mechanically ventilated provide clinically relevant information about abdominal muscle function and weaning outcomes? STUDY DESIGN AND METHODS: This study consisted of two parts, a physiological study conducted in healthy subjects and a prospective observational study in patients who were mechanically ventilated. Abdominal muscle thickness and thickening fraction were measured during cough and expiratory efforts in 20 healthy subjects, and prior to and during a spontaneous breathing trial in 57 patients being ventilated. RESULTS: In healthy subjects, internal oblique and rectus abdominis thickening fraction correlated with pressure generated during expiratory efforts (P < .001). In patients being ventilated, abdominal muscle thickness and thickening fraction were feasible to measure in all patients, and reproducibility was moderately acceptable. During a failed spontaneous breathing trial, thickening fraction of transversus abdominis and internal oblique increased substantially from baseline (13.2% [95% CI, 0.9-24.8] and 7.2% [95% CI, 2.2-13.2], respectively). The combined thickening fraction of transversus abdominis, internal oblique, and rectus abdominis measured during cough was associated with an increased risk of reintubation or reconnection to the ventilator following attempted liberation (OR, 2.1; 95% CI, 1.1-4.4 per 10% decrease in thickening fraction). INTERPRETATION: Abdominal muscle thickening on ultrasound was correlated to the airway pressure generated by expiratory efforts. In patients who were mechanically ventilated, abdominal muscle ultrasound measurements are feasible and moderately reproducible. Among patients who passed a spontaneous breathing trial, reduced abdominal muscle thickening during cough was associated with a high risk of liberation failure. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT03567564; URL: www.clinicaltrials.gov.

Trunk muscle activity during different types of low weighted squat exercises in normal and forefoot standing conditions.

Squats are considered a useful basic exercise for trunk muscle activation. To gain knowledge about trunk muscle activity patterns depending on the barbell position in beginners, we examined squats with low weights in the back, front, and overhead position. METHODS: Twelve healthy adults (6 women/6 men, age: 29.1 (SD 8.0) y, height: 173.4 (6.9) cm, body mass: 70.1 (9.1) kg) randomly performed the three barbell squats in normal and in forefoot standing. Surface electromyography from external (EO) and internal oblique, rectus abdominis, and erector spinae (ES) was recorded. The centre of pressure path length (CoP) and the motion of the lumbar spine were captured. RESULTS: The overhead squat revealed the highest percent muscle activity, where EO (p = 0.009) and ES (p = 0.03) showed the greatest activity. Forefoot standing did not change overall trunk muscle activities (.05< Hedges' g <.29, 0.17 < p < 0.95) although longer CoP path length (.45 < g < 1.3, p < 0.05) was measured. CONCLUSIONS: Squat exercises with low weight are useful to activate trunk muscles. Activity increases with the difficulty of the squat by frontal or overhead loading, but not by standing on the forefoot. The low weighted squat can target well core muscle activity in training with beginners or in rehabilitation.

Clinical Assessment and Thickness Changes of the Oblique and Multifidus Muscles Using a Novel Screening Tool and Exercise Program: A Randomized Controlled Trial.

CONTEXT: Training and assessment of the abdominal and trunk muscles are widely used in the clinical setting. However, it is unknown what types of exercises are most effective in activation of both the global and local stabilizers in these regions. OBJECTIVE: The purpose of this study was to establish the reliability of a novel clinical screening tool (sling screen) to assess the muscles of the abdomen and trunk. The second aim was to use the clinical screening tool and musculoskeletal ultrasound to compare the effects of a rotary-based exercise program that targets both the global and local muscles to the effects of a traditional exercise program on the activation of the abdominal and trunk muscles. DESIGN: Double-blind, randomized controlled trial. SETTING: Sports medicine facility. PARTICIPANTS AND INTERVENTIONS: Thirty-one healthy participants were randomly allocated to receive a single-session rotary-based or traditional "core" exercise program. MAIN OUTCOME MEASURES: The participants were assessed at the baseline and immediately postintervention. The primary outcome measures were muscle thickness examined by musculoskeletal ultrasound and clinical examination of muscle activation using a screening tool. The data were collected by blind assessors. Reliability and validity of a clinical screening tool (sling screen) were also assessed. RESULTS: The analysis of the covariance tests showed a significant increase in oblique thickness for the rotary exercise group. All participants displayed a significant increase in multifidus thickness. The Wilcoxon signed-rank tests revealed a significant increase in clinical assessment scores in the rotary exercise group but not the traditional exercise group. Reliability of the sling screen ranged from moderate to good. CONCLUSION: This clinical trial provides evidence that a rotary-based exercise program may be more effective in producing increases in oblique muscle thickness than traditional "core" exercises in young, healthy adults. The sling screen tool was able to identify these muscle thickness changes. Future studies should investigate how these results correlate to injury risk, other populations, and also how to implement the sling screen into clinical practice.

Comparação da atividade eletromiográfica de músculos do core no exercício prancha ventral com bosu / Comparación de la actividad eletromiográfica de músculos del core en el ejercicio de plancha ventral con bosu / Comparison of electromyographic activity of core muscles in the bridge exercise with bosu

OBJETIVO: Analisar e comparar a atividade eletromiográfica (domínio temporal e espectral) dos músculos reto do abdome, oblíquo externo do abdome, oblíquo interno do abdome, eretor da espinha e multífido no exercício prancha ventral em superfície instável: bosu normal e invertido, durante 45 segundos de contração isométrica. MÉTODO: Quinze voluntários, adultos jovens, saudáveis e fisicamente ativos (21.73 ± 1.31 anos, estatura 177.10 ± 3.90 cm; 74.27 ± 5.38 kg, e 10.97 ± 1.60 % gordura corporal), sem histórico de lombalgia. O sinal eletromiográfica foi analisado no domínio temporal e espectral em três etapas distintas em cada exercício: Início (ETAPA A: 5 a 10 segundos), meio (ETAPA B: 20 a 25 segundos) e fim (ETAPA C: 40 a 45 segundos) e normalizado pela contração isométrica voluntária máxima. Utilizou eletrodos de superfície diferenciais simples com ganho de 20 vezes. No tratamento estatístico foi aplicado teste ANOVA two-way, com post hoc de Sidak (p < 0.05). RESULTADOS: Foi demonstrada similaridade na atividade eletromiográfica no domínio temporal de todos os músculos comparando bosu normal e invertido. Além disso, os resultados exibiram aumento da atividade eletromiográfica e redução da frequência mediana (slope negativo) durante as diferentes etapas em ambos os exercícios. CONCLUSÃO: Devido à similaridade de atividade eletromiográfica, a escolha da utilização da bosu normal ou invertido não se difere para indivíduos treinados, entretanto, a escolha do tempo de 45 segundos é uma estratégia interessante para aumentar a atividade eletromiográfica dos músculos do core e trabalhar a resistência à fadiga muscular, fatores imprescindíveis para prevenção de lombalgia

OBJETIVO: El objetivo de este estudio es analizar la relación entre la actividad electromiográfica de los músculos Reto del Abdomen, Oblicuo Externo, Oblicuo Interno, Eretor de la Espina y Multífido en el ejercicio tabla ventral en superficie inestable: bosu normal e invertido, durante 45 segundos de contracción isométrica. MÉTODO: Quince voluntarios, adultos jóvenes, sanos y físicamente activos (21.73 + 1.31 años, estatura 177.10 + 3.90 cm, 74.27 + 5.38 kg, y 10.97 + 1.60% Grasa Corporal), sin antecedentes de lumbalgia. La señal electromiográfica se analizó, en el dominio temporal y espectral, en tres etapas distintas en cada ejercicio: inicio (ETAPA A: 5 y 10 segundos), medio (ETAPA B: 20 y 25 segundos) y fin (ETAPA C: 40 y 45 segundos). Se utilizaron electrodos de superficie diferenciales simples con una ganancia de 20 veces, y la señal fue analizada en el dominio temporal y normalizada por la máxima contracción isométrica voluntaria. En el tratamiento estadístico se aplicó la prueba de Shapiro Wilk y ANOVA bidireccional, con post hoc de Sidak (p <0.05) para la señal electromiográfica de cada músculo. RESULTADOS: Hubo diferencias significativas entre las fases para todos los músculos, con énfasis en el recto del abdomen y oblicuo externo en las fases B y C e interacción significativa entre el ejercicio y la fase para todos los músculos. El bosu normal e invertido demostraron semejanza en la actividad electromiográfica para todos los músculos, pero en etapas diferentes (C y B / C, respectivamente). CONCLUSIÓN: Debido a la semejanza de actividad electromiográfica, la elección de la utilización de bosu normal e invertido es similar para individuos entrenados, sin embargo, la elección del tiempo de 45 segundos es una estrategia interesante para aumentar la actividad electrromiográfica de los músculos del core y trabajar la resistencia a la fatiga muscular, factores imprescindibles para la prevención de la lumbalgia

OBJECTIVE: To analyze and compare the electromyographic activity of the rectus abdominus, external oblique, internal oblique, erector spinae and multífido muscles in the bridge exercise with an unstable surface: normal and inverted bosu, for 45 seconds of isometric contraction. METHOD: Fifteen volunteers, young, healthy and physically active adults (21.73 ± 1.31 years, height 177.10 ± 3.90 cm, 74.27 ± 5.38 kg, and 10.97 ± 1.60% Body Fat), with no history of low back pain. The electromyographic signal was analyzed in three different steps in each exercise: start (STAGE A: 5 and 10 seconds), middle (STAGE B: 20 and 25 seconds) and end (STAGE C: 40 and 45 seconds). Simple differential surface electrodes with 20-fold gain were used and the signal was analyzed in the temporal domain and normalized by the maximum voluntary isometric contraction. In the statistical treatment, the Shapiro Wilk test and two-way ANOVA, with Sidak post hoc test (p <0.05) were applied to the electromyographic signal of each muscle. RESULTS: There were significant differences between phases for all muscles, with emphasis on rectus abdominus and external oblique in phases B and C and a significant interaction between exercise and phase for all muscles. normal and inverted bosu demonstrated similarity in electromyographic activity for all muscles, but at different stages (C and B / C, respectively). CONCLUSION: Due to the similarity of electromyographic activity, the choice of using normal or inverted bosu does not differ for trained individuals, however, choosing a 45-second time is an interesting strategy to increase the electromyographic activity of core muscles and to work resistance to muscle fatigue, essential factors for the prevention of low back pain

Surface Electromyography of the Internal and External Oblique Muscles During Isometric Tasks Targeting the Lateral Trunk.

CONTEXT: Tasks that activate the lateral trunk muscles are clinically relevant in athletic and rehabilitation programs. However, no electromyography studies have compared tasks aimed at lateral trunk muscle activation. OBJECTIVE: To compare the activation magnitudes of the internal and external obliques between 4 tasks targeting recruitment of the lateral trunk muscles, including the proposal of a novel assessment. DESIGN: Comparative laboratory study. SETTING: University-based biomechanics laboratory. PARTICIPANTS: Sixty-three participants (35 females, age = 23.6 [2.0] y, height = 1.72 [0.10] m, mass = 70.7 [14.4] kg, body mass index = 23.6 [2.86] kg/m2). INTERVENTION(S): Surface electromyography data were recorded bilaterally from the internal and external obliques while the participants performed 2 maximum voluntary contraction tasks followed by 4 isometric tasks. The isometric tasks included feet-elevated side-supported, trunk-elevated side-unsupported, lateral plank, and side-lying hip abduction. MAIN OUTCOME MEASURES: Maximum voluntary contraction-normalized and integrated muscle activities were calculated for targeted and nontargeted muscles in each task. A side-by-task analysis of variance with Bonferroni correction was conducted. RESULTS: The trunk-elevated side-unsupported task strongly activated the internal (199% maximum voluntary contraction) and external (103%) oblique muscles. The feet-elevated side-supported task strongly activated the internal obliques (205%) but not the external obliques (55%). The lateral plank task successfully activated the internal (107%) and external (72%) obliques, but not at the highest levels of the tested tasks. The side-lying hip abduction task was the least effective at activating either the internal (48%) or external (20%) obliques. CONCLUSIONS: We recommend the novel trunk-elevated side-unsupported task for assessing lateral trunk muscle performance. For independent exercise, we recommend the lateral plank task, unless arm or shoulder pathologies are present, whereby the feet-elevated side-supported task may be favorable.

Task-invariance and reliability of anticipatory postural adjustments in healthy young adults.

BACKGROUND: Anticipatory postural adjustments (APAs) occur in the trunk during tasks such as rapid limb movement and are impaired in individuals with musculoskeletal and neurological dysfunction. To understand APA impairment, it is important to first determine if APAs can be measured reliably and which characteristics of APAs are task-invariant. RESEARCH QUESTION: What is the test-retest reliability of latency, amplitude and muscle activation patterns (synergies) of trunk APAs during arm-raise and leg-raise tasks, and to what extent are these APA characteristics invariant across tasks at the individual and group levels? METHODS: 15 young adults (mean age: 23.7 (±3.2) years) performed six trials of a rapid arm raise task in standing and a leg raise task in supine on two occasions. Latency, amplitude and coactivation of APAs in the erector spinae and external/internal oblique musculature were measured, and APA synergies were identified with principle components analysis. Test-retest reliability across the two sessions was calculated with intraclass correlation coefficients. Task-invariance was assessed at the individual level with correlation and at the group level with tests of equivalence. RESULTS: Most variables demonstrated acceptable test-retest reliability. Synergies and many features of APA activation varied across tasks, although at the individual level, motor performance time and amplitude of lumbar erector spinae activation were significantly correlated across tasks. Average pre-motor reaction time, external oblique latency, contralateral oblique amplitude and internal oblique coactivation were equivalent across tasks. SIGNIFICANCE: Characteristics of trunk muscle APAs quantified during a single task may not be representative of an anticipatory postural control strategy that generalizes across tasks. Therefore, APAs must be assessed during multiple tasks with varying biomechanical demands to adequately investigate mechanisms contributing to movement dysfunction. The reliability analysis in this study facilitates interpretation of group differences or changes in APA behavior in response to intervention for the selected tasks.

Can the Use of Unstable Surfaces and Instruction for Conscious Abdominal Contraction Increase the EMG Activity of the Periscapular Muscles During the Dynamic Push-Up?

CONTEXT: It is believed that conscious abdominal contraction (CAC) during exercise encourages greater periscapular activation through existing myofascial connections. On the other hand, it is postulated that the use of unstable surfaces would promote greater neuromuscular demand. OBJECTIVE: To analyze the effect of CAC on periscapular muscle activity during push-up plus exercise on stable and unstable surfaces and to evaluate the correlation between electromyographic (EMG) activity of the serratus anterior (SA) and abdominal oblique muscles. DESIGN: Repeated-measures design in a single group, pre-post CAC. SETTING: Biomechanics laboratory. PARTICIPANTS: Twenty-three male volunteers without a history of lesions in the upper limbs participated in the study. MAIN OUTCOME MEASURES: Five repetitions of push-ups on stable and unstable surfaces were performed with and without instruction for CAC. The normalized amplitude of the EMG activity was obtained from the muscles of the upper, middle, and lower trapezius, SA upper (SA_5th) and lower (SA_7th) portions, external oblique (EO), and internal oblique. RESULTS: CAC increased the activity of the EO, internal oblique, middle trapezius, and SA (P < .05) in both surfaces. The use of the unstable surface increased the EMG activity of the EO, SA_7th, and middle trapezius and decreased the EMG activity of the SA_5th. However, all changes observed in EMG signals were of low magnitude, with effect sizes lower than 0.45. There was a weak correlation between the EMG activity of the EO and SA_5th (r = .24) and a strong correlation between the EO and SA_7th (r = .70). CONCLUSION: The isolated use of CAC or unstable surface during push-up seems to present no practical relevance, but the combined use of these strategies may increase activation of the SA_7th and middle trapezius muscles.

Electromyographic and Kinematic Analysis of the Flexion-Rotation Trunk Test.

García-Vaquero, MP, Ruiz-Pérez, I, Barbado, D, and Vera-Garcia, FJ. Electromyographic and kinematic analysis of the flexion-rotation trunk test. J Strength Cond Res 34(12): 3386-3394, 2020-Although most trunk endurance field protocols are performed in the sagittal or frontal planes, the flexion-rotation trunk (FRT) test combines trunk flexion with rotation, which may be relevant to rotation-related sports. The aim of this study was to describe the trunk and hip muscle activation and fatigue and the range of hip flexion of this test. Twenty-seven physically active males and females performed the FRT test after a period of practice. Electromyographic (EMG) signals were bilaterally collected from the rectus abdominis (RA), internal oblique (IO), and rectus femoris (RF), and hip flexion amplitude was measured using a biaxial electrogoniometer. Because the fast Fourier transform algorithm requires stationary EMG signals, subjects performed a 6-second isometric trunk flexion-rotation repetition just before and just after the test execution (preexecution and postexecution repetitions, respectively). Rectus abdominis showed the highest mean activation levels (approximately 30% maximal voluntary isometric contractions [MVC]) in the preexecution repetition, followed by IO (approximately 20% MVC). Also, the mean power frequency (MPF) significantly decreased from the pre-execution to the postexecution repetition for RA and IO, which shows abdominal muscle fatigue. Although each trunk flexion-rotation repetition involved an average 8-14° hip flexion, the RF activation was lower than 10% MVC, and no significant MPF reduction (i.e., no muscle fatigue) was observed for this muscle. In addition, significant negative correlations were found between the FRT test scores and the normalized EMG amplitudes of RF. Based on these results, the FRT test seems a valid field protocol to assess abdominal muscle endurance in trunk flexion-rotation exertions.

Comparison of the Abdominal Wall Muscle Thickness in Female Rugby Players Versus Non-Athletic Women: A Cross-Sectional Study.

Background and Objectives: Rugby players engage in demanding, high loading muscular activity in the spine. Study of the abdominal wall architecture in female rugby athletes is relevant to the possible muscular asymmetry secondary to sport practice and the relationship between the abdominal wall and the pelvic floor muscles. Activation of the transversus abdominis (TrAb) generates an increase in the bladder neck muscle. Moreover, an increased interrecti distance (IRD) is related to urinary incontinence and has a higher prevalence in athletic women. The aim of the present study was to compare and quantify, with ultrasound imaging (USI), the thickness of the transversus abdominis (TrAb), external oblique (EO), internal oblique (IO), rectus abdominis (RA), and interrecti distance (IRD) in female rugby players versus non-athletic women in order to improve upon existing knowledge about abdominal wall configuration in female athletes. Materials and Methods: A sample of 32 women was recruited at the Universidad Europea Research Lab and divided in two groups: a rugby group (n = 16) and a non-athletic women group (n = 16). The thickness of the TrAb, EO, IO, RA, and IRD were assessed by USI in both groups. Results: There were statistically significant differences for the ultrasound evaluation thickness of the right TrAb (p = 0.011; d = 0.10), EO (p = 0.045; d = 0.74), IO (p = 0.003; d = 1.32), and RA (p = 0.001; d = 1.38) showing a thickness increase for the rugby group with respect to the control group. For the IRD thickness, there were no significant differences (p > 0.05) between groups. Conclusions: An increased TrAb, IO, EO, and RA thickness may be shown in female rugby players versus non-athletic women. Nevertheless, statistically relevant differences were not found for the IRD between both groups.

Electromyographic evaluation of trunk core muscles during Pilates exercise on different supporting bases.

OBJECTIVE: To evaluate the electromyographic (EMG) activity of the rectus abdominis (RA) and internal oblique (IO) muscles during Pilates exercise on different trunk supporting bases. METHODS: Sixteen female Pilates practitioners participated in the study. EMG of the RA and OI muscles was evaluated during the double leg stretch (DLS) exercise on three different supporting bases - mat, long box, and short box. Trunk stability varies according to the size and type of the base. To normalize the data, the RMS value (EMG) obtained during the DLS exercise was divided by the RMS value from the torque test - the maximal voluntary isometric contraction (MVIC) - and multiplied by 100 (%MVIC). One-way repeated-measured analysis of variance (ANOVA) and Bonferroni tests were used to compare data concerning the supporting bases and Student t-test regarding the muscles (p < 0.05). RESULTS: The comparison among the bases involving each muscle - RA or IO (p < 0.05) - showed significant difference (%MVIC) between the mat and the short box. No significant difference was observed between the muscles concerning the exercise on the mat (p = 0.9266), on the long box (p = 0.5113) and on the short box (p = 0.2972). CONCLUSION: The short box increased the activity of the rectus abdominis and internal oblique muscles during exercise. The DLS exercise was able to challenge the stability of the trunk and thus recruit its stabilizer and mobilizer muscles at the same intensity.

Trunk muscle activity among older and obese individuals during one-handed carrying.

Manual material handling (MMH) is associated with the development of work-related musculoskeletal disorders (MSDs). One-handed carrying is a particularly challenging form of MMH. Age and obesity have been increasing among the general and working populations in the United States and worldwide. While older and obese workers are more susceptible to MSDs in comparison to younger, healthy workers, the effects of one-handed carrying on trunk muscle activity among these populations have not been comprehensively studied. In this paper, we evaluate the effects of age and obesity on trunk muscle activity of six trunk muscle pairs during one-handed carrying of different loads. The results suggest that older and obese individuals do not exhibit considerably larger muscle activity than young and non-obese individuals while carrying a load of approximately 10 kg in one hand for relatively short distances. Accordingly, 10 kg appears to be an acceptable load to be occasionally carried in one hand by older and/or obese individuals from a muscle activity perspective.

Effect of Pilates Mat Exercises on Neuromuscular Efficiency of the Multifidus and Internal Oblique Muscles in a Healthy Ballerina.

Physical training has frequently been indicated for ballet dancers to strengthen their trunk muscles, improve their performance, and avoid injuries. The current authors hypothesized that these dancers could benefit from Pilates exercises to stabilize their trunk muscles and improve joint stability and neuromuscular efficiency (NME). Our study aimed at evaluating the NME and isometric strength of the internal oblique (IO) and multifidus (MU) muscles in a healthy 24-year-old classical ballerina before and after an 8-week Pilates exercise intervention. The muscles were tested with electromyography (EMG) and a dynamometer, and the resulting torque and EMG values were used to calculate the NME. Based on the results, the Pilates exercises could improve the NME of the muscles tested, since the torque increased and the EMG activity decreased after the intervention.

Revisiting the effect of manipulating lumbar stability with load magnitudes and positions: The effect of sex on trunk muscle activation.

BACKGROUND: Lumbar spine stability is regularly studied by positioning different loads at different heights and distance and measuring trunk muscle activation changes. Some of these studies have reported sex differences, but this needs to be revisited while controlling for confounding factors. METHOD: 20 males and 20 females sustained three static standing postures, with various loads (0, 5 and 10% of body weight), to evaluate the effect of height and distance. Activation of 12 trunk muscles was recorded with surface electromyography (EMG). RESULTS: Females activated their external obliques a little more than males, with increases ranging between 1.5 and 2.3% of maximal voluntary activation (MVA), which corresponds to strong effect sizes (Cohen's d ranging between 0.86 and 1.13). However, the significant Sex × Height, Sex × Distance and Sex × Load interactions observed for different trunk muscles led to small differential effects (≤1% MVA). Increasing load height slightly increased and decreased back and abdominal muscle activation, respectively, generally by less than 1% MVA. CONCLUSION: The higher activation of the external obliques observed in females might be of clinical value, relative to the required overall trunk muscle activation (5%), to preserve lumbar stability. Other effects were negligible.

Electromyographic Effect of Using Different Attentional Foci During the Front Plank Exercise.

OBJECTIVE: The aim of this cross-sectional study was to examine whether an internal focus on different core muscles during the isometric prone plank exercise increased muscle activity. DESIGN: Twenty university students performed the following five different conditions: regular prone plank (external focus) and prone plank with an internal focus on different muscles. Surface electromyography signals were recorded for the upper rectus abdominis, lower rectus abdominis, external oblique, and lumbar erector spinae. RESULTS: For the upper rectus abdominis, an internal focus on using any muscle increased activity. For the lower rectus abdominis, internal focus on any muscle except the lumbar erector spinae increased activity. No changes were found for external oblique and lumbar erector spinae activity. CONCLUSIONS: Upper rectus abdominis and lower rectus abdominis activities increased during an internal focus on the abdominal muscles. external oblique and lumbar erector spinae activities were nonaffected by an internal focus on any muscle.

Anatomical and functional relationships between external abdominal oblique muscle and posterior layer of thoracolumbar fascia.

The abdominal muscles are important for the stability of the lumbar region through the thoracolumbar fascia (TLF). However, there is not full agreement regarding the posterior transversal continuity of the external abdominal oblique muscle (EO) with the TLF. To clarify this point, 10 cadavers and computed tomography (CT) images from 27 subjects were used to evaluate the transversal continuity of the TLF with the abdominal muscles. The width of the fascial continuity of the EO with the posterior layer of TLF along the posterior border of the EO was also measured (40.70 ±3.92 mm). The epimysial fascia of the EO was in direct continuity with the posterior layer of TLF in eight cadavers and 23 CT images, whereas in two cadavers and four CT images, the epimysial fascia of the EO first fused with the fascia covering the latissimus dorsi, and then, both fasciae were in continuity with the posterior layer of TLF. Therefore, the transversal fascial continuity of the EO could explain the transmission of tension from the EO to the posterior layer of TLF and its importance in maintaining the stability of the lumbar spine through a hydraulic effect. Regarding fascial continuity in the trunk, and taking the EO into consideration, the TLF is formed by the fascia of all the abdominal muscles as the rectus sheath. In this manner, myofascial continuity between the TLF and the abdominal muscles is achieved through the aponeurosis and fascia, which ensures synchronization between the erector spinae and the rectus abdominis. Clin. Anat. 31:1092-1098, 2018. © 2018 Wiley Periodicals, Inc.

Comparison between the Ki-hap technique and verbal encouragement on activation of abdominal muscles in healthy participants.

The aim of this study was to investigate the comparison between a Ki-hap, defined as a psyching-up technique, and verbal encouragement, defined as a verbal command by a third party, on abdominal muscle activation during performance of the crunch exercise in healthy participants. Ninety participants were randomly allocated to the following three groups: crunch only exercise group (CG, n1 = 30), crunch exercise with Ki-hap group (CKG, n2 = 30), and crunch exercise with Ki-hap and verbal encouragement group (CKVG, n3 = 30). The interventions were conducted over three trials with each group, and measurements involving each participant, were performed by a single examiner. The activation of the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were evaluated using electromyography (EMG) during performance of the crunch exercise by the CG, CKG, and CKVG. Our results showed a significantly greater increase in the EMG patterns of all muscles during performance of the crunch exercise in the CKG (p < 0.05) compared to those in the CG and CKVG. The results also showed that there was a significantly greater increase in the activation of the EO and IO muscles in the CKVG (p < 0.05) compared with that in the CG. These findings demonstrated that the addition of the Ki-hap technique and verbal encouragement, during performance of the crunch exercise, improves activation of the abdominal muscles.

Effects of standing on typing task performance and upper limb discomfort, vascular and muscular indicators.

Standing is a popular alternative to traditionally seated computer work. However, no studies have described how standing impacts both upper body muscular and vascular outcomes during a computer typing task. Twenty healthy adults completed two 90-min simulated work sessions, seated or standing. Upper limb discomfort, electromyography (EMG) from eight upper body muscles, typing performance and neck/shoulder and forearm blood flow were collected. Results showed significantly less upper body discomfort and higher typing speed during standing. Lower Trapezius EMG amplitude was higher during standing, but this postural difference decreased with time (interaction effect), and its variability was 68% higher during standing compared to sitting. There were no effects on blood flow. Results suggest that standing computer work may engage shoulder girdle stabilizers while reducing discomfort and improving performance. Studies are needed to identify how standing affects more complex computer tasks over longer work bouts in symptomatic workers.