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This study analysed the muscle activity levels and patterns of the major thigh muscle activation during training sections at different intensities of on-water rowing. 9 experienced rowers performed 2 imposed-pace sections (Bl and B2) and 2 maximal-speed sections (start, 500 m) of on-water rowing. The knee angle, power output, mean torque and stroke rate were measured using specific instrumentation and were synchronised with surface electromyography signals of 5 superficial quadriceps and hamstring muscles. Bl and B2 sections were not significantly different regarding mechanical parameters and EMG activities, while the start phase induced large differences. The EMG patterns for Bl, B2 were similar (cross-correlation coefficients (CC) ranged between 0.972-0.984) and the moderate CC found between both Bl and start (0.605-0.720) and B2 and start (0.629-0.720). Our results suggest that the hamstring muscles have a motor action and contribute to the power production during the leg drive. During an all-out 500 m section, a decrease in power and stroke rate was found (up to 20%). However, EMG patterns were not time shifted for all muscles. During the leg drive, the muscle activity levels of the quadriceps muscles were unchanged, while the activity of the hamstring muscles decreased. [ABSTRACT FROM AUTHOR]

Background: Core stability training (CST) is effective in improving postural balance, core endurance, and self-reported outcomes in different populations. This study aimed to investigate the effect of CST in soccer players with groin pain (GP)., Hypothesis: CST would improve postural balance performance, core endurance, and self-reported outcomes in soccer players with GP., Study Design: Randomized controlled trial., Level of Evidence: Level 2., Methods: Soccer players with GP who met the selection criteria were assigned randomly to a CST (CSTG, n = 10) or a control (CG, n = 10) group. The CG undertook no additional physical activity program besides their usual training. The CSTG performed a 12-week CST comprising 76 ~75 min sessions. Static (force platform) and dynamic (Y-Balance test) postural balance, core endurance (McGill trunk endurance tests), and self-reported outcomes (Copenhagen Hip and Groin Outcome Score [HAGOS]) were assessed before and immediately after the 12-week CST., Results: Significant improvements were seen in dynamic postural balance ( P = 0.04 to <0.01), HAGOS scores ( P = 0.02 to <0.01), and core endurance measures ( P < 0.01) in the CSTG in posttest compared with pretest session and compared with CG. Static bipedal postural balance measures showed significant improvements (eyes open, P = 0.02; eyes closed, P < 0.01) in the CSTG in posttest compared with pretest session. However, no significant differences ( P > 0.05) were observed between CSTG and CG after the training period., Conclusion: A 12-week CST improved static (foam surface) and dynamic postural balance, core endurance measures, and HAGOS scores., Clinical Relevance: The beneficial effect of CST on improving postural balance, core endurance, and self-reported outcomes in soccer players with GP suggests that this training would be an important feature of rehabilitation programs for these players. Coaches and clinicians should prioritize CST training when designing rehabilitation programs., Competing Interests: The authors report no potential conflicts of interest in the development and publication of this article.

The literature offers limited information on the effect of obesity on the rate of force development (RFD), a critical parameter for mobility in older adults. The objectives of this study were to explore the influence of obesity on the RFD in older adults and to examine the association between this neuromuscular parameter and walking speed. The participants (42 older adults) were classified into two groups: the control group (CG, n = 22; mean age = 81.13 ± 4.02 years; body mass index (BMI) = 25.13 ± 3.35 kg/m 2 ), and the obese group (OG, n = 20; mean age = 77.71 ± 2.95 years; BMI = 34.46 ± 3.25 kg/m 2 ). Walking speed (m/s) was measured using the 10 m walking test. Neuromuscular parameters of the plantar flexors were evaluated during a maximal voluntary contraction test using a dynamometer. The RFD was calculated from the linear slop of the force-time curve in the following two phases: from the onset of the contraction to 50 ms (RFD 0-50 ) and from 100 to 200 ms (RFD 100-200 ). The gait speed was lower in the OG compared to the CG ( p < 0.001). The RFD 50/100 and RFD 100/200 were lower in the OG compared to the CG ( p < 0.001). The RFD 50/100 was found to be the predominant influencer on gait speed in the OG. In conclusion, obesity negatively impacts the RFD in older adults and RFD stands out as the primary factor among the studied parameters influencing gait speed.

Background: Excessive body weight is associated with gait alterations. In none of previous studies, body fat distribution has been considered as a factor that could change gait parameters and induce different neuromuscular adaptations., Objective: This multicenter, analytical, and cross-sectional study aimed to investigate the influence of the body mass distribution on gait parameters and ankle muscle coactivation in obese individuals., Methods: Three distinct groups were included in the study: a non-obese control group (CG, n = 15, average age = 32.8 ± 6.5 years, BMI = 21.4 ± 2.2 kg/m2), an obese-android group characterized by a Waist to Hip Ratio (WHR) greater than 1 (OAG, n = 15, age = 32.4 ± 3.9 years, BMI = 41.4 ± 3.9 kg/m2, WHR = 1.2 ± 0.2), and an obese-gynoid group with a WHR less than 1 (OGG, n = 15, age = 35.4 ± 4.1 years, BMI = 40.0 ± 5.7 kg/m2, WHR = 0.82 ± 0.3). All participants walked on an instrumented gait analysis treadmill at their self-selected walking speed for one minute. Spatiotemporal parameters, walking cycle phases, vertical ground reaction force (GRFv) and center of pressure (CoP) velocity were sampled from the treadmill software. Electromyography (EMG) activity of the gastrocnemius medialis (GM), the soleus (SOL) and tibialis anterior (TA) were collected during walking and used to calculate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA) for the different walking cycle phases., Results: Compared to OAG, OGG walked with shorter and larger strides, lower CoP velocity and GRFv. During the single support phase, SOL/TA coactivation was higher in OAG compared to OGG (p < .05). During the propulsion phase, SOL/TA coactivation was higher in OGG compared to OAG (p < .05)., Conclusion: Gait parameters and ankle muscle coactivation in obese individuals seem to be strongly dependent on body mass distribution. From the biomechanical point of view, body mass distribution changes gait strategies in obese individuals inducing different neuromuscular adaptations during the single support and propulsion phases., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Maktouf et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Athletes with patellar tendinopathy (PT) have postural stability deficits; however, the underlying mechanisms and factors responsible remain unknown. The effect on postural stability in PT of decreased quadriceps strength, altered proprioception, lower-limb muscle tightness, and knee pain, which explain postural stability deficiency in other populations, is uninvestigated., Hypothesis: Proprioceptive acuity, muscle tightness, quadriceps strength, and pain predict postural stability in athletes with PT., Study Design: Cross-sectional comparative study., Level of Evidence: Level 2., Methods: A total of 43 athletes with PT and 43 healthy athletes were enrolled. Static and dynamic postural stability, proprioceptive acuity, muscle tightness, quadriceps strength, and pain were evaluated using a force platform, Y-balance test (YBT), a weight discrimination protocol, a goniometer, an isometric dynamometer, and a valid questionnaire, respectively., Results: Athletes with PT had significantly worse static and dynamic postural stability in the affected limb (AL) compared with the nonaffected limb (NAL) ( P < 0.01) and the control group ( P < 0.01). Athletes suffering from PT revealed lower quadriceps strength ( P < 0.01), proprioceptive acuity ( P = 0.02), and higher muscle tightness in the AL compared with the NAL and controls. Quadriceps weakness of the AL and pain in athletes with PT explained the variance of dynamic postural stability impairment., Conclusion: Athletes with PT have postural stability deficiency compared with healthy peers. Our results demonstrate that quadriceps muscle weakness and pain are the factors that explain postural stability impairment., Clinical Relevance: These results can assist clinicians in the design of therapeutic balance rehabilitation programs by acting not only on pain relief but also on quadriceps strengthening through resistance training to avoid subsequent injuries in athletes with PT., Competing Interests: The authors report no potential conflicts of interest in the development and publication of this article.

Objectives: The study sought to evaluate possible relationships between dynamic postural balance and pain, core stability, and hip range of motion in soccer players who were experiencing groin pain (GP). Furthermore, the study aimed to compare these measurements in symptomatic and asymptomatic players., Methods: The study included 42 male soccer players experiencing GP and an equal number of asymptomatic players. Dynamic postural balance, pain, hip range of motion and trunk endurance were measured., Results: The GP group revealed reduced dynamic balance performance (p < 0.01-0.001) in injured and non-injured limbs compared to control group. Further, players experiencing GP demonstrated lower hip range of motion in internal (p < 0.05) and total rotations (p < 0.01) in the injured limb, and lower trunk endurance (p < 0.001) compared to their asymptomatic peers. In general, core stability was associated ( r  = 0.13-0.61, p < 0.05-0.001) with the poor dynamic balance performance in the GP group while standing on injured and non-injured limbs. No significant correlations between dynamic postural balance, pain and hip range of motion were observed., Conclusion: Poor core endurance was found to be associated with dynamic balance disorders in soccer players experiencing GP. This information can aid in the development of targeted strategies to enhance dynamic postural balance in these players., Competing Interests: There are no relevant financial or non-financial competing interests to report., (© 2024 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Sarcopenic obesity (SO), characterized by age-related muscle loss and excess body fat, significantly impairs postural control. However, limited research has explored the effects of concurrent exercise training on neuromuscular strategies during postural control in older adults with SO. The study enrolled 50 older adults with SO, split into an intervention group (IG, n = 25, mean age = 76.1 ± 3.5 years; mean BMI = 34.4 ± 4.0 kg/m 2 ) and a control group (CG, n = 25, mean age = 75.9 ± 5.4 years; mean BMI = 32.9 ± 2.3 kg/m 2 ). Participants in the IG were engaged in 60-min Total Mobility Plus Program (TMP) sessions three times a week for four months, while the CG maintained their typical daily activities. Standardized evaluations were conducted both before and after the intervention. These assessments included the Romberg and Timed Up and Go (TUG) tests, as well as the measurement of Center of Pressure (CoP) displacements parameters under various conditions. Additionally, ankle muscle activities were quantified during postural control evaluations and maximal voluntary contractions of plantar and dorsal flexors. Post-intervention results revealed a significant reduction of the standing time measured in the Romberg (-15.6%, p < 0.005) and TUG (-34.6%, p < 0.05) tests. Additionally, CoP area and velocity were notably reduced in various conditions ( p < 0.05). Postural control improvements were associated with an increase of strength ( p < 0.05) and decrease of ankle muscle activation ( p < 0.05). These findings highlight the reversibility of neuromuscular system alterations associated with the synergistic effects of sarcopenia and obesity, emphasizing the trainability of postural control regulation within this population. By incorporating these insights into clinical practice and public health strategies, it seems possible to optimize the health and well-being of older adults with SO.

Background: Static postural control disorders have been documented in soccer players suffering from groin pain (GP). Understanding the mechanisms of these disorders is crucial in designing rehabilitation programs., Objectives: To (i) assess static postural control and core stability in soccer players suffering from GP compared to their peers and (ii) explore the relationship between these two parameters., Methods: This cross-sectional study involved 42 male soccer players suffering from GP (GP group: GPG) and 42 healthy players (control group: CG). Static postural control (stabilometric platform) and core stability (core endurance tests) were assessed., Results: Center of pressure velocity in the GPG was significantly higher compared to the CG during bipedal stance on the firm surface with eyes closed (2.66 [95 % CI: 0.86-3.67]; p < 0.01) and on the foam one (p < 0.001) in both conditions; eyes opened (2.88 [95 % CI: 1.42-4.43]) and closed (5.88 [95 % CI: 2.66-9.10]), and on the IL in eyes closed (12.54 [95 % CI: 4.27-20.80]; p < 0.01). Besides, GPG revealed significant (p < 0.001) lower core stability measures compared to CG. No significant associations (p > 0.05) were observed between static postural control and core stability in GPG., Conclusion: Soccer players suffering from GP showed static disorders of postural control compared with their peers. These impairments were not associated with measures of core stability. These findings provide insight into the direction of future research exploring the mechanisms underlying deficits in static postural control in soccer players suffering from GP., Competing Interests: All authors have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript. All authors declare no conflicts of interest., (© 2023 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

The potential impact of a specific physical activity program on biomechanical gait parameters and neuromuscular strategies around the ankle joint in older adults with sarcopenic obesity (SO) remains largely unexplored. The objective of this study was to investigate the effectiveness of a 24-week posture, strengthening, and motricity (PSM) program on improving neuromuscular strategies and biomechanical gait parameters in older adults with SO. 40 participants were randomly assigned to either the trained group (TG) and the control group (CG). Only the TG received the PSM program. Standardized evaluations were performed before and after the intervention, including walking tests on an instrumented gait analysis treadmill to evaluate biomechanical gait parameters and EMG activity of ankle muscles. After the PSM program, TG exhibited an increase in comfortable walking speed (+80%, p < 0.001) and step length (+38%, p < 0.05). Moreover, TG demonstrated a reduction in CoP velocity (-26%, p < 0.01). These gait modifications were associated with decreased muscle activity during the different gait phases ( p < 0.05). The PSM program effectively improved gait and neuromuscular capacities in older adults with SO. Notably, these results shed light on the remarkable trainability of neuromuscular capacities in older adults with SO, despite the adverse effects of aging and obesity.

This study aimed to investigate static and dynamic postural balance inter-limb asymmetries in athletes with unilateral patellar tendinopathy (UPT) and estimate subsequent lower extremity musculoskeletal injury risk compared to controls. Twenty-eight athletes with UPT were recruited. Twenty-eight healthy athletes served as controls. Static postural balance inter-limb asymmetry (symmetry index: SI) was assessed based on differences in the mean centre of pressure (CoP) velocity (CoP v ) values between the affected leg (AL) and non-affected leg (NAL) for the UPT group, and the dominant leg (DL) and non-dominant leg (NDL) for controls. Outcome variables were dynamic postural balance, assessed with inter-limb asymmetry using the Y Balance Test (YBT), and injury risk. In static balance, SI values were significantly ( P <0.001) higher in the UPT group compared to controls. In dynamic balance, normalized inter-limb asymmetry values were also significantly higher in athletes with UPT compared to controls in anterior ( P <0.001), posteromedial ( P <0.001) and posterolateral ( P <0.01) directions, and in the composite score ( P <0.001). Furthermore, the incidence of sustaining a non-contact lower extremity injury during the follow-up period (10 months) was significantly higher ( P <0.05) in the UPT group compared to controls. Athletes with UPT had postural balance inter-limb asymmetries. Moreover, they had increased subsequent lower extremity musculoskeletal injury risk compared to controls. Since most athletes with UPT continue to train and compete, adequate training and rehabilitation programmes should be implemented to prevent potential subsequent injury occurrence.

Background: The practice of regular physical activity can reduce the incidence of certain cancers (colon, breast, and prostate) and improve overall survival after treatment by reducing fatigue and the risk of relapse. This impact on survival has only been demonstrated in active patients with lymphoma before and after treatment. As poor general health status reduces the chances of survival and these patients are most likely to also have sarcopenia, it is important to be able to improve their physical function through adapted physical activity (APA) as part of supportive care management. Unfortunately, APA is often saved for patients with advanced blood cancer. As a result, there is a lack of data regarding the impact of standardized regular practice of APA and concomitant chemotherapy as first-line treatment on lymphoma survival., Objective: This study aimed to assess the impact of a new and open rehabilitation program suitable for a frail population of patients treated for diffuse large B-cell lymphoma (DLBCL)., Methods: PHARAOM (Physical Activity Program for the Survival of Elderly Patients with Lymphoma) is a phase 3 randomized (1:1) study focusing on a frail population of patients treated for DLBCL. The study will include 186 older adult patients with DLBCL (aged >65 years) receiving rituximab and chemotherapy. Overall, 50% (93/186) of patients (investigational group) will receive APA along with chemotherapy, and they will be supervised by a dedicated qualified kinesiologist. The APA program will include endurance and resistance training at moderate intensity 3 times a week during the 6 months of chemotherapy. The primary end point of this study will be event-free survival of the patients. The secondary end points will include the overall survival, progression-free survival, prevalence of sarcopenia and undernutrition, and patients' quality of life. This study will be conducted in accordance with the principles of the Declaration of Helsinki., Results: Recruitment, enrollment, and data collection began in February 2021, and 4 participants have been enrolled in the study as of July 2022. Data analysis will begin after the completion of data collection. Future outcomes will be published in peer-reviewed health-related research journals and presented at national congress, and state professional meetings. This publication is based on protocol version 1.1, August 3, 2020., Conclusions: The PHARAOM study focuses on highlighting the benefits of APA intervention on survival during the period of first-line treatment of patients with DLBCL. This study could also contribute to our understanding of how an APA program can reduce complications such as sarcopenia in patients with lymphoma and improve their quality of life. By documenting the prevalence and relationship between sarcopenia and exercise load, we might be able to help physicians plan better interventions in the care of patients with DLBCL., Trial Registration: ClinicalTrials.gov NCT04670029; https://clinicaltrials.gov/ct2/show/NCT04670029., International Registered Report Identifier (irrid): DERR1-10.2196/40969., (©Jonas Dubu, Sébastien Boyas, Virginie Roland, Sébastien Landry, Anne-Lise Septans, Magali Balavoine, Hugues Bourgeois, Yoann Pointreau, Fabrice Denis, Christophe Letellier, Katell Le Dû. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 25.11.2022.)

Background: Recent studies reported postural balance disorders in patients and soccer players with groin pain (GP) compared to controls. Since postural balance asymmetry identified after an initial injury contributes for subsequent injuries, identification of this asymmetry in soccer players with GP may highlight the risk of sustaining subsequent noncontact lower extremity musculoskeletal injuries in these players. Therefore, the aims of this study were to (i) examine static and dynamic unipedal postural balance asymmetry in soccer players with GP compared to healthy ones, and (ii) quantify the risk of subsequent noncontact lower extremity injuries in these players., Research Question: Do soccer players with GP exhibit higher static and dynamic unipedal postural balance asymmetry, and higher risk of sustaining subsequent injuries compared to controls?, Methods: In this prospective case control study, 27 soccer players with non-time loss GP (GP group: GPG), and 27 healthy ones (control group: CG) were enrolled. Static and dynamic unipedal postural balance asymmetry were evaluated with a force platform using symmetry index (SI), and Y-balance test (Y-BT), respectively. Additionally, subsequent noncontact lower extremity musculoskeletal injuries were tracked for 10 months., Results: The GPG revealed higher (p < 0.01) SI in eyes closed condition, higher (p < 0.001) side-to-side asymmetry in anterior, posteromedial and posterolateral reach distances and in composite Y-BT score compared to CG. They showed lower (p < 0.001) composite score for injured limb and higher (p < 0.001) side-to-side asymmetry in posteromedial reach distance compared to the cut-off values of 89.6 % and 4 cm, respectively. Moreover, GPG exhibited higher odds (OR= 7.48; 95 % CI = 2.15, 26.00; p < 0.01) of sustaining subsequent injuries compared to CG., Significance: The Y-BT should be instituted into existing pre-participation physical examinations to screen for soccer players with non-time loss GP at an elevated risk of sustaining subsequent injuries. This could help coaches and clinicians make valid return to play decisions., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Objective: To compare postural control performance between athletes with and without patellar tendinopathy (PT)., Design: Case-control study., Participants: Fifty-eight athletes, 29 with PT (PT group: PTG) and 29 healthy ones (control group: CG)., Main Outcome Measures: Static and dynamic postural control were assessed with a force platform and the Y-Balance Test (Y-BT), respectively. Quadriceps strength of both limbs was evaluated using an isometric dynamometer., Results: The PTG exhibited significantly (p < 0.05) higher centre of pressure (CoP) values than the CG on the foam surface, and significantly lower (p < 0.001) anterior, posteromedial and posterolateral normalized reach distances, and composite score in dynamic postural control on the injured limb (IL) compared to non-injured limb (NIL) and dominant limb (DL) of the CG. The quadriceps muscle strength was significantly lower on the IL compared to the NIL (p < 0.01) and DL (p < 0.05) of the CG., Conclusion: Athletes suffering from PT exhibited worse static and dynamic postural control compared to healthy peers. As players with PT frequently continue training despite their tendon pain, physiotherapists and clinicians should incorporate balance rehabilitation programs in the treatment of these players, not only to prevent further potential injuries but also to enhance sport performance., Competing Interests: Declaration of competing interest None declared., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objective: To compare postural balance outcomes between soccer players with and without groin pain (GP)., Design: Case-control study., Setting: Laboratory., Participants: Fifty-four soccer players, 27 with GP (GP group: GPG) and 27 healthy ones (control group: CG)., Main Outcome Measures: Static and dynamic postural balance were assessed with a force platform and Y-balance test (Y-BT), respectively. Hip abduction, internal rotation (IR), external rotation (ER) and total rotation (TR) of both limbs were evaluated., Results: The GPG exhibited significant higher centre of pressure values in the bipedal posture only on the foam surface in eyes opened and closed compared to controls. Besides, they had lower anterior, posteromedial and posterolateral reach distances and composite Y-BT score on the injured limb (IL) compared to non-injured limb (NIL) and dominant-limb (DL) of the CG. Moreover, they showed lower abduction, IR, ER, and TR on the IL compared to NIL and DL., Conclusions: Dynamic unipedal postural balance disorder could be one of the limiting factors of performance in soccer players with non-time loss GP. Hence, postural balance data in these players could enable sport coaches and physical therapists to better understand the mechanisms contributing for performance decrease., Competing Interests: Declaration of competing interest None declared., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objective: The purposes of this study were to investigate the combined effects of age and obesity on gait and to analyze the relationship between age and obesity on ankle muscle activities during walking., Materials and Methods: 4 groups; the young non-obese control group (CG, n = 50, age = 31.8 ± 4.5 years; BMI = 21.4 ± 2.2 kg/m 2 ), the young obese group (OB, n = 30, age = 35.4 ± 4.1 years; BMI = 38.6 ± 3.5 kg/m 2 ), the non-obese older adults group (OA, n = 20, age = 76.1 ± 3.5 years; BMI = 24.4 ± 1.1 kg/m 2 ) and the obese older adults group (OBOA, n = 20, age = 79.6 ± 5.7 years; BMI = 35.5 ± 2.7 kg/m 2 ) walked on an instrumented gait analysis treadmill at their preferred walking speed. Spatiotemporal parameters, walking cycle phases, Vertical ground reaction force (GRFv) and center of pressure (CoP) velocity were sampled from the treadmill software. Electromyography (EMG) activity of the gastrocnemius medialis (GM), the soleus (SOL) and tibialis anterior (TA) were also collected during the walking test. A forward stepwise multiple regression analysis was performed to determine if body weight or age could predict ankle muscle activities during the different walking cycle phases., Results: Compared to OB, OBOA walked with higher CoP velocity, shorter stride, spending more time in support phase (p < .05). These manifestations were associated with higher TA and SOL activities during the 1st double support (1st DS) and higher TA activity during the single support (SS) (p < .05). Compared to OA, OBOA walked with lower GRFv, shorter and wider stride and spend more time in SU (p < .05). Moreover, SOL, TA and GM activities of OBOA were higher compared to OAG during 1st DS, SS and 2nd Double support (2nd DS), respectively (p < .05). During the 1ST DS, the stepwise multiple regression revealed that age accounted for 87% of the variance of TA activity. The addition of age contributed a further 16% to explain the variance TA activity. During the SS, age accounted for 64% and 46% of the variance of SOL and TA activity respectively. The addition of the body weight added further 15% and 66% of the variation of SOL and TA activity respectively. During the 2nd DS, body weight accounted for 86% of the variance and the addition of the body weight added a further 17% to explain the high level of GM., Conclusion: Age in obese adults and obesity in older adults should be considered separately to evaluate neuromuscular responses during walking and, subsequently, optimize the modality of treatment and rehabilitation processes in obese individuals in order to reduce and/or prevent the risk of falls., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: It is well established that obesity is associated with deterioration in postural control that may reduce obese adults' autonomy and increase risks of falls. However, neuromuscular mechanisms through which postural control alterations occur in obese adults remain unclear., Objective: To investigate the effects of obesity on muscle coactivation at the ankle joint during static and dynamic postural control., Materials and Methods: A control group (CG; n = 20; age = 32.5 ± 7.6 years; BMI = 22.4 ± 2.2 Kg/m²) and an obese group (OG; n = 20; age = 34.2 ± 5.6 years; BMI = 38.6 ± 4.1 Kg/m²) participated in this study. Static postural control was evaluated by center of pressure (CoP) displacements during quiet standing. Dynamic postural control was assessed by the maximal distance traveled by the CoP during a forward lean test. Electromyography activity data for the gastrocnemius medialis (GM), soleus (SOL) and tibialis anterior (TA) were collected during both quiet standing and forward lean tests. Muscle activities were used to calculate two separate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA, respectively)., Results: CoP displacements were higher in the OG than in the CG for quiet standing (p < 0.05). When leaning forward, the maximal distance of the CoP was higher in the CG than in the OG (p < 0.05). Only the CI value calculated for SOL/TA was higher in the OG than in the CG for both static and dynamic tasks (p < 0.05). The SOL/TA CI value in the OG was positively correlated with CoP displacements during quiet standing (r = 0.79; p < 0.05)., Conclusion: Obesity increases muscle coactivation of the soleus and tibialis anterior muscles at the ankle joint during both static and dynamic postural control. This adaptive neuromuscular response may represent a joint stiffening strategy for enhancing stability. Consequently, increased ankle muscle coactivation could not be considered as a good adaptation in obese adults., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The objective of this study was to investigate the effect of obesity on markers of neuromuscular fatigability of ankle muscles and their potential relationships with postural control capacities. Two groups: non-obese control group (CG; n = 15; age = 40.1 ± 13.9 years; BMI = 23.9 ± 2.8 kg/m 2 ) and obese group (OG; n = 15; age = 44.2 ± 12.4 years; BMI = 42.2 ± 5.2 kg/m 2 ), performed two postural tasks with and without vision in order to collect parameters of center of pressure (CoP) displacements; area (cm 2 ), velocity (mm/s), length (cm) and the ratio length/area. Fatigability was estimated during 60 repeated maximal voluntary contractions of plantar (PF) and dorsal flexors (DF). The maximal force, critical force (F cr ) presenting the asymptote of the force-time evolution and rate of the force decrease (τ) were extracted. Results reported that CoP parameters were higher in OG compared to CG in all postural tasks (p < 0.05). F cr of PF and DF were 39% and 28% lower respectively in OG compared to CG (p < 0.05). Only τ of PF was 12% lower in OG (p < 0.05). F cr of PF was negatively correlated with the ratio length/area in OG in all postural tasks (r = 0.86 and r = 0.85, respectively, p < 0.05). We concluded that obesity is associated with a decreased F cr of ankle muscles expressing the intensity threshold above which fatigue develops drastically. We also revealed that decreased fatigability threshold particularly that of PF, could partly explain postural control alterations in obese adults., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Objective: To evaluate the role of obesity in the effects of physical activity (PA) on postural control and functional and physical capacities in the older adults and to assess the effectiveness of a PA program on these capacities., Methods: Six obese (age = 78.8 [3.7] y; body mass index > 30 kg/m2), 7 overweight (age = 80.9 [2.8] y; 25 < body mass index < 30 kg/m2), and 6 normal weight (age = 80.8 [5.7] y; body mass index < 25 kg/m2) older adults performed the time up and go test, the 6-minute walk test, and the Tinetti test. Static and dynamic (forward leaning) postural control tests were also assessed. All these tests were similarly assessed 4 months later, during which only the obese group and overweight group participated in a PA program., Results: Before PA, results of the time up and go test, 6-minute walk test, Tinetti test, quiet standing, and forward lean tests revealed that physical capacities and static and dynamic postural control were impaired in the obese group when compared to the normal weight group. After PA, results of quiet standing, physical and functional tests were improved for obese group., Conclusions: Obesity is an additional constraint to age-related postural control and functional and physical capacities deteriorations. Nevertheless, a PA program is effective in improving balance and functional capacities in obese older adults.

This study aimed to evaluate the within- and between-session reliability of force, velocity and power performances and to assess the force-velocity relationship during the deadlift high pull (DHP). Nine participants performed two identical sessions of DHP with loads ranging from 30 to 70% of body mass. The force was measured by a force plate under the participants' feet. The velocity of the 'body + lifted mass' system was calculated by integrating the acceleration and the power was calculated as the product of force and velocity. The force-velocity relationships were obtained from linear regression of both mean and peak values of force and velocity. The within- and between-session reliability was evaluated by using coefficients of variation (CV) and intraclass correlation coefficients (ICC). Results showed that DHP force-velocity relationships were significantly linear ( R ² > 0.90, p  < 0.05). Within sessions and between sessions, mean and peak forces during DHP showed a strong agreement (CV < 3%, ICC > 0.94), mean and peak velocities showed a good agreement (CV < 9%, 0.78 < ICC < 0.92). It was concluded that DHP performance and its force-velocity relationships are highly reliable and can therefore be utilised as a tool to characterise individuals' muscular profiles.

Background: The individual effects of fatigue and age on postural control have been extensively studied. However, there is a lack of knowledge about the combined effects of fatigue and age on postural control and posture., Research Question: The purpose of this study was to investigate the influence of age and muscle fatigue on bipedal stance postural control and posture., Methods: Twenty-three participants, fourteen young adults and nine older adults performed 30-s bipedal postural trials before and after fatigue. The fatigue protocol consisted in repeating heel raises until exhaustion. Back, hip, knee and ankle joint angles and centre of pressure (COP) displacements were recorded with a 3D motion capture system and a force plate., Results: Fatigue induced similar increases in sway area and COP velocity for both populations. This was associated with a forward displacement of the COP position for both populations but with different postural adaptations. Similar increased flexions (+1.7 to 1.8°) for all joint angles (ankle, knee, hip and back) joints were observed after fatigue for older adults, whereas young adults mainly showed increased flexion for the ankle joint (+3.1°) and decreased flexion at the hip (-1.2°)., Significance: It can be argued that older adults act on all joints because they are too weak to sufficiently modify any joint individually, contrary to young adults. These posture adaptations may be strategies to cope with fatigue by limiting the reliance on fatigued plantarflexors, increasing ankle stiffness, increasing the sensitivity of muscle spindles, increasing the number of degrees of freedom of the task., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective: The aim of the study was to investigate the influence of age and/or obesity on postural control, ankle muscle activities during balance testing and force production capacities., Materials and Methods: 4 groups; control group (CG; n = 25; age = 31.8 ± 7.5 years; BMI = 21.4 ± 2.5 kg/m 2 ), obese group (OG; n = 25; age = 34.4 ± 9.5 years; BMI = 39.6 ± 5.4 kg/m 2 ), elderly group (EG; n = 15; age = 77.1 ± 8.4 years; BMI = 24.4 ± 1.3 kg/m 2 ) and obese elderly group (ObEG; n = 12; age = 78.6 ± 6.6 years; BMI = 34.5 ± 3.1 kg/m 2 ) performed maximal voluntary contraction (MVC) before testing to calculate the maximal relative force of ankle plantar flexor (PF) and dorsal flexor (DF) muscles. Center of pressure (CoP) parameters and the electromyography (EMG) activity of PF and DF muscles were collected during MVC, quiet standing and limit of stability (LoS) testing along antero-posterior and medio-lateral axes., Results: Maximal relative force was higher in EG and ObEG than CG and OG, respectively (p < 0.001). CoP parameters, distance traveled along the antero-posterior axis and EMG activity of PF were higher in OG, EG and ObEG compared to CG (p < 0.001) and in EG compared to ObEG (p < 0.05).The EMG activity of PF was positively correlated with CoP parameters in OG and ObEG (r > 0.6; p < 0.05). Maximal relative force of PF (r > -0.6; p < 0.05) was negatively correlated with CoP parameters in ObEG and EG., Conclusion: Obesity-related postural control alteration is associated with increased activity of PF. This neuromuscular adaptation may reflect deteriorations of the proprioceptive system and is likely additional to age-related muscular impairments. This may be a mechanism by which obesity increases postural control alterations in elderly., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study aimed to assess the influence of an adapted physical activity program on self-esteem and quality of life in breast cancer patients. Twenty-three women diagnosed with breast cancer and treated by mastectomy formed 2 groups. The experimental group practiced adapted physical activity for 12 weeks, while the control group did not. All participants answered questionnaires regarding their self-esteem and quality of life at the beginning of the program and 6 and 12 weeks after that. Self-esteem, physical self-perception, quality of life, global health status, pain, and breast symptoms were improved only in the group which practiced adapted physical activity., (© 2018 S. Karger AG, Basel.)

The dual-task paradigm has previously been used to investigate the attentional demands associated with postural control. Previous studies have identified both the focus of attention and the difficulty of a postural task as potential factors influencing dual-task performance. The aim of this study was to examine how the instructed focus of attention influences dual-task performance during quiet standing tasks of various levels of difficulty. Thirteen young adults participated in two testing sessions consisting of standing as still as possible on a force platform in different postural conditions, while simultaneously performing a simple reaction time (RT) task. Postural task difficulty was manipulated by various combinations of three bases of support (feet together, tandem and single leg) and two visual conditions (eyes opened and closed). Participants were instructed to focus on either their balance or their RT performance, depending on the testing session. When comparing postural control with respect to session focus, anterior-posterior sway velocity decreased with the addition of the simple RT task when the focus was on balance, but only during the more difficult dual-task conditions. In contrast, sway area and medial-lateral sway velocity did not change between the two instructed focus sessions. Participants responded faster in all dual-task conditions when focusing on RT performance than on balance. The modified attention allocation index indicated that participants' ability to modulate their allocation of attentional resources to respond positively to instruction was more pronounced in the most challenging postural condition. The present findings could have important implications for the interpretation of dual-task performance in both clinical and research settings.

The purpose of this study was to investigate the influence of fatiguing exercise intensity on the nature and extent of fatigue-induced changes in neuromuscular function and postural stability in quiet standing. We also explored the contribution of selected neuromuscular mechanisms involved in force production to postural stability impairment observed following fatigue using an approach based on multivariate regressions. Eighteen young subjects performed 30-s postural trials on one leg with their eyes closed. Postural trials were performed before and after fatiguing exercises of different intensities: 25, 50 and 75% of maximal isometric plantarflexor torque. Fatiguing exercises consisted of sustaining a plantarflexor isometric contraction at the target intensity until task failure. Maximal isometric plantarflexor torque, electromyographic activity of plantarflexor and dorsiflexor muscles, activation level (twitch interpolation technique) and twitch contractile properties of plantarflexors were used to characterize neuromuscular function. The 25% exercise was associated with greater central fatigue whereas the 50 and 75% exercises involved mostly peripheral fatigue. However, all fatiguing exercises induced similar alterations in postural stability, which was unexpected considering previous literature. Stepwise multiple regression analyses showed that fatigue-related changes in selected parameters related to neuromuscular function could explain more than half (0.51≤R(2)≤0.82) of the changes in postural variables for the 25% exercise. On the other hand, regression models were less predictive (0.17≤R(2)≤0.73) for the 50 and 75% exercises. This study suggests that fatiguing exercise intensity does not influence the extent of postural stability impairment, but does influence the type of fatigue induced and the neuromuscular function predictors explaining changes in postural variables.

The aim of the present study was to investigate changes in joint angles and limb positions accompanying postural control impairments induced by fatigue of the ankle plantarflexor muscles and vision removal. Thirteen subjects performed unipedal standing tasks with and without vision before and after isometric fatigue of the plantarflexor muscles. Results indicated that to compensate for the negative effects of fatigue and vision removal on postural control, participants increased flexion at the ankle, knee and back while the free lower limb and the pelvis moved backward and the upper limbs forward. These strategies could be performed to increase the role of non-fatigued muscles and optimize the use of all the joints implicated in unipedal standing., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

The purpose of this study was to investigate the changes in postural control and in posture induced by ankle plantarflexor fatigue during a unipedal stance task. We also studied the postural strategies in the antero-posterior and medio-lateral planes used by participants to maintain balance. Thirteen young adults were asked to stand barefoot on their preferred leg as still as possible for 30s with vision or without vision. Participants performed postural trials before and after a fatigue protocol that consisted of standing on toes until exhaustion. Centre of pressure (COP) displacements were measured with a force platform and electrogoniometers were placed at the ankle, knee and hip joints of the support leg to monitor articular angles. Relationships between changes in articular angles and displacements of the COP in the antero-posterior and medio-lateral planes were tested using cross-correlations. Sway area and velocity increased with fatigue, but only without vision. A posterior shift of the mean COP position was also observed after fatigue. Ankle and hip joints were more flexed after fatigue. Moderate to good relationships between COP displacements and ankle angles were observed before and after fatigue in both planes whereas these relationships were low for hip and knee joints. Ankle plantarflexors fatigue induced impairment in postural control and changes in posture. To compensate for the effects of fatigue, participants increased the flexion of the ankle and/or the hip joints but conserved the ankle strategy as the dominant postural strategy in both planes., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Fatiguing exercises used across studies to induce alterations in postural control are diverse and may explain the different findings reported. This study aimed to compare the effects of two types of fatiguing plantarflexion exercises on postural control on a firm and a compliant surface. Ten healthy young men (29 ± 4 years) were asked to stand as steadily as possible for 30 s, blindfolded with feet together, on a firm and a compliant surface before and immediately after an isometric and an isokinetic fatiguing exercise., Results: Maximal force reduction due to fatigue was found significant but similar between exercises. No significant difference was found between the fatiguing exercises on all Center of Pressure (CoP) parameters. Both fatiguing exercises induced increases in CoP excursion area, CoP variability and CoP velocity in both planes (antero-posterior, mediolateral) on the compliant surface. On the firm surface, both fatiguing exercises only induced increases in CoP variability and CoP velocity in the fatigued plane (antero-posterior)., Conclusions: Isometric and isokinetic fatiguing exercises, when producing a similar level of force reduction, induce similar decreases in postural control. The effects of fatigue on postural control in healthy young men are more pronounced when standing on a compliant surface, i.e. when proprioceptive information at the ankle is altered.

The authors aimed to assess the effect of vision on variations in attentional resources allocated to postural control during tasks of various levels of difficulty. Test-retest reliability of postural and cognitive parameters was also evaluated. Twenty adults stood quietly on a force platform during 30-s trials (primary task). Twelve conditions involving combinations of three bases of support, two vision conditions, and the presence or absence of a simple reaction time task (secondary task) were tested. Baseline trials of the reaction time task were also performed with the participants seated. Reaction time and postural parameters demonstrated good to excellent test-retest reliability in most conditions. Postural control was altered by the reduction of the base of support and by the absence of vision. Maintaining an upright stance increased reaction time compared with a seated position, indicating that quiet standing tasks required some attention even in young adults. Changes in postural steadiness were correlated with changes in reaction time, showing a significant relationship between the difficulty of the postural task and the attentional resources allocated to postural control. However, reaction time increased with the reduction of the base of support only without vision. This dual task paradigm showed that vision can compensate for the increase in attentional demands during the most difficult postural tasks.

The purpose of endurance time (T (lim)) prediction is to determine the exertion time of a muscle contraction before it occurs. T (lim) prediction would then allow the evaluation of muscle capacities limiting fatigue and deleterious effects associated with exhaustive exercises. The present study aimed to analyze the influence of exercise intensity and joint angle on T (lim) prediction using changes in surface electromyographic (sEMG) signals recorded during the first moments of the exercise. Fifteen male performed four knee extensions sustained until exhaustion that were different in exercise intensity (20% or 50% of maximal voluntary torque-MVT) and in joint angle (40 or 70º, 0° = full extension). T (lim) prediction was explored using some parameters of the sEMG signals from rectus femoris, vastus medialis and vastus lateralis muscles. Changes in sEMG parameters (root mean square, mean power frequency and frequency banding 6-30 Hz) were expressed using the slope of the linear regression and the area ratio index. Results indicated that relationships between changes in sEMG signal and T (lim) (0.51 < r < 0.83) were greater for experimental conditions associated with higher exercise intensity (50% MVT) and so to lower time duration. Knee joint angle had little influence on T (lim) prediction results. Results also showed higher T (lim) prediction considering spectral parameters and area ratio. This could be in relation to differences in relative contribution of central and peripheral fatigue that seems to change according to the exercise intensity, but also to the influence of psychological factors that increases with the duration of the task.