The Effectiveness of External Verbal Feedback on Balance in Athletes with Chronic Ankle Instability.

Chronic ankle instability (CAI) is characterized by muscle weakness and impaired neuromuscular control. This study aimed (a) to assess the impact of external verbal feedback on the dynamic balance of athletes with CAI and (b) to examine the maintenance of dynamic balance ability after the end of the completion of the intervention balance program. Thirty athletes (mean age 21.63 ± 1.53) were randomly divided into three groups: an experimental group with external verbal feedback, 1st control group without external verbal feedback and the 2nd control group without balance training and without feedback. Assessments using a balance board and the 'Y-balance' test were conducted before and after the balance training period. Additionally, participants completed the Cumberland Ankle Joint Instability Tool. A retention test of balance ability was administered after the 4-week intervention period. Statistical analysis revealed a significant overall improvement in balance (F(2,36) =5.96, p = 0.006, partial η2 =0.249), including those with no balance training, but no significant differences between the groups. Thus, the external verbal feedback did not show a positive impact on the balance ability between the three different groups. Also, the experimental group with the external verbal feedback demonstrated maintenance of dynamic balance learning ability. Although it appears that balance training has a positive effect on the dynamic balance of individuals with CAI, a non-positive impact of external verbal feedback was found. Also, it appears that external verbal feedback significantly led to sustained retention of balance learning ability. Further research is recommended to validate these findings.

Exploring 3D Pelvis Orientation: A Cross-Sectional Study in Athletes Engaged in Activities with and without Impact Loading and Non-Athletes.

Female athletes subjected to various types of impact loading, especially over a long period of time, may experience changes in their pelvic orientation, which may affect their sport performance and increase the likelihood of injury. The aim of the present study was to determine whether female athletes involved in high-impact loading sports (HILS), odd-impact loading sports (OILS), and repetitive non-impact loading sports (NILS) demonstrate changes in pelvis orientation compared to non-athletes (NATH). Pelvic orientation was determined using Euler/Cardan angles, calculated from the coordinates of the right, and left anterior superior iliac spines and pubic symphysis via a novel method. Two-way ANOVA tests showed significant differences between groups for pelvis position in the frontal plane (p < 0.05), with HILS and OILS demonstrating greater pelvic obliquity compared to NILS athletes and NATH. Significant main effects were also obtained for directions within the sagittal plane (p < 0.001). Significant within-group differences were observed in sagittal pelvic position among female athletes engaged in NILS (p < 0.01) and non-athletes (NATH) (p < 0.05), with a greater anterior pelvic tilt compared to posterior. Our findings suggest that pelvis orientation in female athletes across sports is influenced by sport-specific impact loads, potentially affecting performance and injury occurrence.

Effects of Artificially Induced Leg Length Discrepancy on Treadmill-Based Walking and Running Symmetry in Healthy College Students: A Lab-Based Experimental Study.

Leg length discrepancy (LLD) is a common postural deviation of musculoskeletal origin, which causes compensatory reactions and often leads to injury. The aim of the study was to investigate the effect of artificially induced LLD on gait symmetry by means of the spatiotemporal gait parameters and ground reaction forces (GRFs) using a treadmill equipped with capacitive sensors (instrumented) as well as the EMG activity of trunk and hip muscles during walking and running. Twenty-six healthy male and female college students were required to perform two sets of four 2.5-min walking and running trials on an instrumented treadmill at 5.6 and 8.1 km·h-1, respectively, without (0) and with 1, 2, and 3 cm LLD implemented by wearing a special rubber shoe. Statistical analysis was performed using one-way repeated measures or a mixed-design ANOVA. Most spatiotemporal gait parameters and GRFs demonstrated an increase or decrease as LLD increased either on the short-limb or the long-limb side, with changes becoming more apparent at ≥1 cm LLD during walking and ≥2 cm LLD during running. The EMG activity of trunk and hip muscles was not affected by LLD. Our findings showed that gait symmetry in terms of treadmill-based spatiotemporal parameters of gait and GRFs is affected by LLD, the magnitude of which depends on the speed of locomotion.

Effects of Load Carriage on Postural Control and Spatiotemporal Gait Parameters during Level and Uphill Walking.

Load carriage and uphill walking are conditions that either individually or in combination can compromise postural control and gait eliciting several musculoskeletal low back and lower limb injuries. The objectives of this study were to investigate postural control responses and spatiotemporal parameters of gait during level and uphill unloaded (UL), back-loaded (BL), and front-loaded (FL) walking. Postural control was assessed in 30 asymptomatic individuals by simultaneously recording (i) EMG activity of neck, thoracic and lumbar erector spinae, and rectus abdominis, (ii) projected 95% ellipse area as well as the anteroposterior and mediolateral trunk displacement, and (iii) spatiotemporal gait parameters (stride/step length and cadence). Measurements were performed during level (0%) and uphill (5, 10, and 15%) walking at a speed of 5 km h-1 without and with a suspended front pack or a backpack weighing 15% of each participant's body weight. The results of our study showed that postural control, as indicated by increased erector spinae EMG activity and changes in spatiotemporal parameters of gait that manifested with decreased stride/step length and increased cadence, is compromised particularly during level and uphill FL walking as opposed to BL or UL walking, potentially increasing the risk of musculoskeletal and fall-related injuries.

Ankle and foot function in female athletes involved in in-water and dry-land sporting activities.

BACKGROUND: The stability and mobility of the ankle and foot joints are thought to be improved by cross-training, i.e., transferring the beneficial effects acquired from performing one sporting activity to those required to perform another. This study aimed to investigate the effect of long-term participation with in-water and dry-land sports activities (IWSA, DLSA) on ankle and foot function. METHODS: The study sample consisted of 28 healthy competitive female athletes involved in IWSA (N.=14) and DLSA (N.=14) for <8 years, as well as 15 females not involved in sporting activities (NISA). The isometric strength of the ankle dorsi flexors (ADF), plantar flexors (APF), and subtalar invertors and evertors (SIN, SEV), the ankle dorsi and plantar flexion, and subtalar/forefoot inversion and eversion passive range of motion (ROM), and the static and dynamic balance were assessed in each participant's supportive lower limb. RESULTS: IWSA athletes demonstrated significantly greater isometric strength in ADF (P<0.01), SIN (P<0.01), and SEV (P<0.05) compared to DLSA athletes and in ADF (P<0.001), SIN (P<0.01) and SEV (P<0.05) compared to NISA individuals with differences between DLSA athletes and NISA individuals being not significant. Between-groups differences on isometric APF strength, passive ROM of the ankle and foot joints, and postural balance were not significant. CONCLUSIONS: DLSA athletes could benefit from long-term participation with IWSA, at least in terms of increasing isometric strength of the ankle and foot stabilizers, as their function does not appear to improve after long-term participation with the sports of their choice, at least compared to NISA individuals.

Neuromuscular control of the lower extremities can be better enhanced by applying ankle taping and kinesiological taping rather than elastic bandaging: a randomized control study in amateur soccer players.

[Purpose] This study evaluated the effects of ankle elastic bandaging, taping, and kinesiology taping on the neuromuscular control of the lower extremities before and after their application and after exercise in soccer athletes. [Participants and Methods] Fifty-five amateur soccer players were randomly divided into four research sub-groups either receiving bandaging (n=15), taping (n=15), and kinesiology taping (n=15) on their ankle or serving as controls (n=10). The dynamic stability of the non-dominant limb was assessed through the star excursion balance test (SEBT) in three research conditions: a) before sports taping application, b) after the application, and c) after a 15 min laboratory simulation of soccer activities. [Results] Taping and kinesiology taping improved the dynamic stabilization of the lower limb more statistically significantly than bandaging. The addition of exercise significantly improved the SEBT results in the taping and kinesiology taping more than the bandaging and control groups. [Conclusion] Exercise activates the proprioceptive mechanisms of the lower limb and improves its neuromuscular control. This functional improvement of the lower limb appears to be enhanced after ankle taping and kinesiology taping compared with elastic bandaging and controls.

Effects of Artificially Induced Breast Augmentation on the Electromyographic Activity of Neck and Trunk Muscles during Common Daily Movements.

A female breast can be a potential source of musculoskeletal problems, especially if it is disproportionately large. The purpose of the present study was to examine the effect of artificially induced breast volume on the EMG activity of neck and trunk musculature during common everyday movements. The EMG activity of the sternocleidomastoid (SCM), the upper trapezius (UT), and the thoracic and lumbar erector spinae (TES, LES) were recorded during 45° trunk inclination from the upright standing and sitting postures (TIST45°, TISI45°) as well as during stand-to-sit and sit-to-stand (STSI, SIST) in 24 healthy females with minimal and ideal breast volume (M-NBV, I-NBV). All movements were performed before and after increasing M-NBV and I-NBV by 1.5-, 3.0-, 4.5-, and 6-times using silicone-gel implants. Significantly higher EMG activity for TES and LES were found at 6.0- and ≥4.5-times increase the I-NBV, respectively, compared to smaller breast volumes during TIST45°. EMG activity of UT was higher, and TES was lower in M-NBV females compared to I-NBV females in all movements but were significantly different only during SIST. The female breast can affect the activity of neck and trunk muscles only when its volume increases above a certain limit, potentially contributing to muscle dysfunction.

Differences between Systems Using Optical and Capacitive Sensors in Treadmill-Based Spatiotemporal Analysis of Level and Sloping Gait.

Modern technology has enabled researchers to analyze gait with great accuracy and in various conditions based on the needs of the trainees. The purpose of the study was to investigate the agreement between systems equipped with optical and capacitive sensors in the analysis of treadmill-based level and sloping gait. The spatiotemporal parameters of gait were measured in 30 healthy college-level students during barefoot walking on 0% (level), -10% and -20% (downhill) and +10% and +20% (uphill) slopes at hiking-related speeds using an optoelectric cell system and an instrumented treadmill. Inter-system agreement was assessed using the Intraclass Correlation Coefficients (ICCs) and the 95% limits of agreement. Our findings revealed excellent ICCs for the temporal and between moderate to excellent ICCs for the spatial parameters of gait. Walking downhill and on a 10% slope demonstrated better inter-system agreement compared to walking uphill and on a 20% slope. Inter-system agreement regarding the duration of gait phases was increased by increasing the number of LEDs used by the optoelectric cell system to detect the contact event. The present study suggests that systems equipped with optical and capacitive sensors can be used interchangeably in the treadmill-based spatiotemporal analysis of level and sloping gait.

Acute Effects of Static Self-Stretching Exercises and Foam Roller Self-Massaging on the Trunk Range of Motions and Strength of the Trunk Extensors.

Although the effectiveness of static self-stretching exercises (SSSEs) and foam roller self-massaging (FRSM) in joint range of motion and muscle strength of the lower limbs has been extensively investigated, little is known about their effectiveness on the posterior trunk muscles. The present study aimed to investigate the acute effects of two 7-min SSSEs and FRSM intervention protocols on the range of trunk movements and the strength of the trunk extensors. Twenty-five healthy active males (n = 14) and females (n = 11) performed each intervention separately, one week apart. The range of motion (ROM) of the trunk-hip flexion (T-HF), the ROM of the trunk side-flexion (TSF) and rotation (TR) bilaterally, as well as the isometric maximum strength (TESmax) and endurance (TESend) of the trunk extensors were measured before and after each intervention. The ROMs of T-HF, TSF, and TR were significantly increased following both SSSEs and FRSM. The TESmax and TESend were also significantly increased after FRSM, but decreased following SSSEs. While both interventions were effective in increasing the range of motion of the trunk, a single 7-min session of FRSM presented more advantages over a similar duration SSSEs protocol due to the increase in the strength of the trunk extensors it induced.

Acute L-Citrulline Supplementation Increases Nitric Oxide Bioavailability but Not Inspiratory Muscle Oxygenation and Respiratory Performance.

The present study aimed to investigate whether acute L-citrulline supplementation would affect inspiratory muscle oxygenation and respiratory performance. Twelve healthy males received 6 g of L-citrulline or placebo in a double-blind crossover design. Pulmonary function (i.e., forced expired volume in 1 s, forced vital capacity and their ratio), maximal inspiratory pressure (MIP), fractional exhaled nitric oxide (NO•), and sternocleidomastoid muscle oxygenation were measured at baseline, one hour post supplementation, and after an incremental resistive breathing protocol to task failure of the respiratory muscles. The resistive breathing task consisted of 30 inspirations at 70% and 80% of MIP followed by continuous inspirations at 90% of MIP until task failure. Sternocleidomastoid muscle oxygenation was assessed using near-infrared spectroscopy. One-hour post-L-citrulline supplementation, exhaled NO• was significantly increased (19.2%; p < 0.05), and this increase was preserved until the end of the resistive breathing (16.4%; p < 0.05). In contrast, no difference was observed in the placebo condition. Pulmonary function and MIP were not affected by the L-citrulline supplementation. During resistive breathing, sternocleidomastoid muscle oxygenation was significantly reduced, with no difference noted between the two supplementation conditions. In conclusion, a single ingestion of 6 g L-citrulline increased NO• bioavailability but not the respiratory performance and inspiratory muscle oxygenation.

Fatigue-Induced Inter-Limb Asymmetries in Strength of the Hip Stabilizers, Postural Control and Gait Following a Unilateral Countermovement Vertical Jump Protocol.

It is generally accepted that neuromuscular overload and fatigue of one lower limb can affect the functional ability of the ipsilateral limb, and possibly the contralateral limb, increasing the likelihood of injury. The purpose of the current study was to examine the effect of a unilateral countermovement vertical jump (UCVJ) fatigue protocol on the neuromuscular function of the ipsilateral as well as the contralateral lower limb. The isometric strength of the hip stabilizers, postural control via posturographic analysis during the Y-Balance-Test (YBT), and the stance-phase-of-gait were assessed in 24 healthy physical active males and females before and after execution of a UCVJ fatigue protocol. The fatigue protocol included 5 sets of 20 maximum UCVJs performed on the supportive leg, with a 30-s break between sets. Following a 16.8% decline in vertical jump performance and an associated 2.3-fold increase in perceived exertion, our findings revealed significant post-fatigue inter-limb differences regarding postural control. The post-fatigue inter-limb differences regarding the isometric strength of the hip stabilizers and the stance-phase-of-gait parameters were not significant. Our findings showed that a 100 UCVJs session is likely to induce significant inter-limb differences in postural control, possibly increasing the risk of lower limb injury.

The effectiveness of Ergon Instrument-Assisted Soft Tissue Mobilization, foam rolling, and athletic elastic taping in improving volleyball players' shoulder range of motion and throwing performance: a pilot study on elite athletes.

[Purpose] The purpose of this pilot study was to investigate the effectiveness of instrument-assisted soft tissue mobilization (IASTM), foam rolling, and athletic elastic taping on improving elite volleyball players' shoulder range of motion (ROM) and throwing performance. [Participants and Methods] Fifteen elite male volleyball players (mean age: 24 ± 4.54 years; mean height: 177 ± 0.08 cm; mean weight: 81 ± 7.71 kg) received shoulder Ergon IASTM, foam rolling, and elastic taping treatment in random order on both upper extremities once a week for three weeks. Pre-and post-treatment assessments of their shoulders' ROM and functional throwing performance were performed. [Results] Ergon IASTM technique resulted in significantly higher shoulder flexion ROM values than foam rolling and elastic taping. Foam rolling, in turn, showed better results than athletic elastic taping. Moreover, the Ergon IASTM technique resulted in significantly higher OSP values than athletic elastic taping. No significant differences were observed between the therapeutic interventions in terms of FTPI. [Conclusion] This pilot study on elite athletes provides evidence that both IASTM and foam rolling techniques may improve their passive shoulder ROM compared to elastic athletic taping while Ergon IASTM can also enhance their shoulder throwing performance.

Effects of instrument-assisted soft-tissue mobilization at three different application angles on hamstring surface thermal responses.

[Purpose] This study aimed to examine the thermal skin responses (thermal buildup and retention rate) to instrument-assisted soft tissue mobilization (IASTM) procedures applied on hamstrings at different angles. [Participants and Methods] Thirty university students (age: 20 ± 4 years, weight: 70.61 ± 9.11 kg, height: 168.5 ± 7.5 cm) received three sessions of 10-min Ergon® IASTM treatment on their dominant limbs' hamstrings at 20°, 60°, and 90° application angles, respectively. The skin temperature was measured with a thermometer immediately before and after treatment, and every minute thereafter until it returned to the baseline value. [Results] IASTM resulted in a significant increase in skin temperature irrespective of the application angle. The thermal retention rate produced by the treatment at a 90° angle was significantly higher than that produced by the 20° application angle (78.9 vs. 64.53 min). No significant differences were observed between the 60° and 90° angle applications (72.5 vs. 78.9 min). [Conclusion] IASTM application at 60° and 90° angles can increase and retain the hamstring's skin temperature for more than an hour, creating the conditions for potential positive adaptations to local metabolism and muscle tone.

A comprehensive method for assessing postural control during dynamic balance testing.

Postural control, despite its complexity, has been investigated based on single or multiple domain parameters, mainly under static conditions. The purpose of this study was to investigate whether semi-squatting in one leg, in contrast to simply standing in one leg, can challenge the postural control in a more dynamic manner similar to those encountered during sporting activities, using posturographic-based parameters coupled with EMG data of the ankle musculature. Our findings revealed that the decreased stability induced with single-leg semi-squatting (SLSQ) required primarily the contribution of the tibialis anterior and the peroneus brevis, as opposed to the medial gastrocnemius and lateral gastrocnemius who were the main controllers of body posture during single-leg standing (SLST) with open eyes. The lower variability found in the CoP-based parameters and the EMG activity of the muscle under investigation suggests that postural control can be more accurately assessed under dynamic conditions such as with SLSQ compared to the more static SLST test. Multi-factorial analysis of postural control combining posturographic and EMG data, particularly under dynamic conditions, can provide useful information in the diagnosis and rehabilitation of clinical cases where the assessment of muscle dysfunction is required to design a rehabilitation program and monitor patient progress. •Simultaneous recordings of posturographic-based parameters and the EMG activity of the ankle/foot musculature suggest that postural control is challenged more during SLSQ.•Postural control with SLSQ is mainly controlled by the tibialis anterior and peroneus brevis in response to a greater anteroposterior- compared to mediolateral-directed sway of the body.•The limited body sway elicited with the traditional SLST test is mainly controlled by the gastrocnemius muscle.•Postural control may be assessed more accurately under dynamic conditions such as with SLSQ as opposed to the standard SLST test.

Posterior thigh thermal skin adaptations to radiofrequency treatment at 448 kHz applied with or without Indiba® fascia treatment tools.

[Purpose] This study aimed to evaluate the posterior thigh's skin thermal responses to 448-kHz radiofrequency-based therapy applied either in the form of standard application (Indiba®Activ) or combined soft tissue treatment (Indiba®Fascia treatment). [Participants and Methods] Ten healthy males (22 ± 3 years of age, weight 75.2 ± 4.9 kg, height 178.5 ± 4.7) received four different treatments which included a) Indiba®Activ (IA) radiofrequency treatment, b) Indiba®Fascia (IF), c) Indiba®Activ placebo (IAP) and d) Indiba®Fascia Placebo (IFP) in the posterior thigh of their dominant lower limb, while the non-dominant served as the control. Skin temperature was recorded pre- and post-treatment and every minute until the surface temperature reached pre-treatment levels using a wireless infrared thermometer. [Results] Both radiofrequency-based therapy groups IA and IF led to a significant increase in skin temperature compared to placebo applications. The IF intervention led to an average retention of elevated temperature for 164.2 minutes compared to 54.8 minutes of IA, 23.17 of IFP and 17.6 minutes of IAP. [Conclusion] These findings indicate that radiofrequency treatment at 448 kHz can induce and sustain significant thermal skin adaptations reflecting an increased blood circulation and metabolism of underlying tissues.

Ankle muscles activation and postural stability with Star Excursion Balance Test in healthy individuals.

INTRODUCTION: The ankle joint, a part of the kinetic chain of the lower limb, plays a significant role in the maintenance of postural stability during bipedal and unipedal balancing activities. This study aimed to evaluate the neuromuscular control of the ankle joint and the postural stability while executing the Star Excursion Balance Test (SEBT), by recording the EMG activity of the extrinsic ankle musculature and the displacement of the center of pressure (CoP). METHODS: The EMG activity of the tibialis anterior (TA), the peroneus brevis (PB) and the medial and lateral gastrocnemius (GM, GL), along with the anteroposterior and mediolateral displacements (APd and MLd) of CoP as well as the plantar pressure distribution of the supportive lower limb were recorded during reaching to the eight directions of SEBT in 29 healthy, physically active college students (15 males and 14 females; mean ± SD of age 25.6 ± 4.5 yrs.; height: 172.5 ± 8.2 cm; body weight: 67.7 ± 13.6 kg; and BMI: 22.6 ± 2.9 kg/m2). RESULTS: The tibialis anterior muscle demonstrated the greatest EMG activity during SEBT, followed by the PB, GL and GM muscles. The increased EMG activity of TA and PB during the execution of all posterior-oriented and lateral directions coincided with a decreased APd of CoP and increased reaching distances. The opposite occurred during the execution of all the anterior-oriented and medial directions. The differences among the directions of SEBT regarding the EMG activity of GL, GM and the mediolateral displacement of CoP were, in general, not significant. CONCLUSIONS: The neuromuscular control of the ankle joint and the associated postural stability during SEBT was highly depended upon the activation level of TA and PB, which should be considered by clinicians and sports specialists when using this test for screening and/or rehabilitation purposes.

Scapular muscles' activity in female volleyball players with scapular asymmetry in the resting position.

BACKGROUND/AIM: Resting scapular asymmetry with a more protracted and depressed position of the scapula in the dominant throwing side relative to the scapula of the contralateral side is commonly detected in overhead athletes with both healthy and disabled shoulders. It has been proposed that possible alterations in the EMG activity of periscapular muscles due to asymmetric position of the scapula may alter its kinematics leading to shoulder pathology. The aim of the current study was to identify possible alterations in the activation of periscapular muscles of healthy female volleyball players with scapular asymmetry in the resting position. METHODS: Resting position of the scapula was determined in 37 healthy professional female volleyball players. Twenty-two players, with the scapula of the dominant side in a more protracted and depressed position compared to the non-dominant side, were classified as the asymmetry group. Fifteen players with almost symmetrical position of both scapulae comprised the control group. All participants performed an upper extremity closed chain exercise (knee push-ups) on a stable (floor) and an unstable surface (BOSU platform), while the EMG activity of serratus anterior (SA), upper trapezius (UT) and middle trapezius (MT) was recorded bilaterally. RESULTS: No significant group (asymmetry vs. control) by side (dominant vs. non-dominant) by surface condition (floor vs. BOSU platform) interaction was detected with regard to the EMG activity of SA, UT and MT. Although not statistically significant the asymmetry group demonstrated a tendency for reduced EMG activity of the SA on the dominant compared to the contra-lateral side and compared to the dominant side of the control group. CONCLUSIONS: The EMG activity of periscapular muscles (SA, UT and MT) was not affected during execution of a close chain exercise in healthy female volleyball players with the scapula of the dominant side in a more protracted and depressed resting position.

Regulation of Granulocyte Colony-Stimulating Factor and Its Receptor in Skeletal Muscle is Dependent Upon the Type of Inflammatory Stimulus.

The cytokine granulocyte colony-stimulating factor (G-CSF) binds to its receptor (G-CSFR) to stimulate hematopoietic stem cell mobilization, myelopoiesis, and the production and activation of neutrophils. In response to exercise-induced muscle damage, G-CSF is increased in circulation and G-CSFR has recently been identified in skeletal muscle cells. While G-CSF/G-CSFR activation mediates pro- and anti-inflammatory responses, our understanding of the role and regulation in the muscle is limited. The aim of this study was to investigate, in vitro and in vivo, the role and regulation of G-CSF and G-CSFR in skeletal muscle under conditions of muscle inflammation and damage. First, C2C12 myotubes were treated with lipopolysaccharide (LPS) with and without G-CSF to determine if G-CSF modulates the inflammatory response. Second, the regulation of G-CSF and its receptor was measured following eccentric exercise-induced muscle damage and the expression levels we investigated for redox sensitivity by administering the antioxidant N-acetylcysteine (NAC). LPS stimulation of C2C12 myotubes resulted in increases in G-CSF, interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-α (TNFα) messenger RNA (mRNA) and an increase in G-CSF, IL-6, and MCP-1 release from C2C12 myotubes. The addition of G-CSF following LPS stimulation of C2C12 myotubes increased IL-6 mRNA and cytokine release into the media, however it did not affect MCP-1 or TNFα. Following eccentric exercise-induced muscle damage in humans, G-CSF levels were either marginally increased in circulation or remain unaltered in skeletal muscle. Similarly, G-CSFR levels remained unchanged in response to damaging exercise and G-CSF/G-CSFR did not change in response to NAC. Collectively, these findings suggest that G-CSF may cooperate with IL-6 and potentially promote muscle regeneration in vitro, whereas in vivo aseptic inflammation induced by exercise did not change G-CSF and G-CSFR responses. These observations suggest that different models of inflammation produce a different G-CSF response.

Static and dynamic body balance following provocation of the visual and vestibular systems in females with and without joint hypermobility syndrome.

OBJECTIVES: Joint hypermobility syndrome (JHS) is a heritable disorder of the connective tissue characterized by excessive joint movement, musculoskeletal pain and neurophysiological deficits (i.e. decreased proprioceptive acuity, altered neuromuscular reflexes). Such deficits may affect body balance thus increasing the risk of injury. The present study aimed at examining static and dynamic body balance following challenge of the visual and vestibular systems in individuals with JHS. METHODS: The sample consisted of 21 females with JHS and 20 controls without signs of JHS. Static body balance was assessed by the degree of anteroposterior and mediolateral deviation of the center of pressure, during 20-sec single-leg stances with eyes opened (EO), eyes closed (EC) and eyes opened with head extension (EO-HE) using a foot pressure platform. Dynamic body balance was assessed by the number of landing and balance errors committed during a multiple single-leg-hop-stabilization test. RESULTS: Nonparametric analysis showed that the JHS-group demonstrated significantly greater (a) mediolateral deviation during single-leg-stance with EO (p < 0.01), (b) mediolateral and anteroposterior deviation during single-leg-stance with EO-HE (p < 0.05), and (c) number of landing errors (p < 0.05) compared to the control group. CONCLUSIONS: Poor static balance following challenge of the vestibular system may be justified by vestibular deficiency and/or insufficient proprioceptive capabilities of the neck. Impairments of dynamic balance in individuals with JHS may be attributed to proprioceptive deficits, which can alter feedforward and feedback mechanisms.

EMG activation of trunk and upper limb muscles following experimentally-induced overpronation and oversupination of the feet in quiet standing.

Kinematic studies have shown that experimentally-induced overpronation or oversupination of the subtalar joint may alter the position of the legs, hips and pelvis and consequently the trunk and upper limb. The purpose of the present study was to examine whether such foot deformity affects the activity of muscles that act on the trunk and upper limb. Twenty-eight healthy individuals (11 males and 17 females) 21.4±1.9 years of age without skeletal deformity, leg length discrepancy (LLD), overpronated or oversupinated feet or excessive lateral pelvic inclination volunteered for the study. Bilateral EMG recordings of the latissimus dorsi, pectoralis major and rectus abdominis were undertaken for 30-s with each subject in the relaxed standing position and at 5° and 10° bilateral or unilateral overpronation or oversupination of the foot on the dominant side using wooden wedge-shape blocks. The recorded EMG activity was normalised based on the EMG activity produced by the muscles under investigation during maximum isometric voluntary contraction. The findings of the present study revealed that neither bilateral nor unilateral overpronation/oversupination of the feet induced a significant alteration of the EMG activity of the latissimus dorsi, pectoralis major and rectus abdominis on either the dominant or non-dominant side. These findings suggest that in the absence of other major structural deformity bilateral or unilateral foot overpronation or oversupination does not affect the EMG activity of muscles that act on the trunk and upper limb in quiet standing.