{"title":"Comparing shoulder muscle activity in symptomatic and asymptomatic groups: the influence of normalization technique.","authors":"Angelica E Lang, Soo Y Kim","doi":"10.1080/23335432.2025.2537403","DOIUrl":"https://doi.org/10.1080/23335432.2025.2537403","url":null,"abstract":"<p><p>Maximum voluntary contractions (MVCs) are the standard normalization method for muscle activity, but can be hindered by pain and injury. Submaximal normalization may be a viable option. The study objective was to compare muscle activation between symptomatic and asymptomatic groups with MVC and submaximal normalization to determine if similar relative between-groups differences could be detected. Eighteen participants, divided into symptomatic and asymptomatic groups, performed isometric MVCs and six dynamic functional tasks. EMG data were normalized using MVC and submaximal values from a weighted overhead lift. MVCs achieved higher activation levels for most muscles, but submaximal normalization provided comparable values for serratus anterior. Significant between-group differences were observed during the Comb Hair, with higher activation in the symptomatic group for the upper trapezius, middle trapezius, and supraspinatus across both normalizations. The serratus anterior during the Overhead Reach and lower trapezius in the Tie Apron were also different between groups with both normalizations. There were some significant findings that emerged from only one normalization method. Submaximal normalization may be a viable alternative to MVC normalization for select muscles and upper limb pathological populations. Submaximal normalization allowed for meaningful comparisons of muscle activation patterns during functional tasks without the need for maximum force exertion.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"12 1","pages":"18-27"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144692388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David Alan Phillips, Skylar Paletta, Michael Perlet
{"title":"Voluntary contractions underestimate peak muscle activity in drop jumps.","authors":"David Alan Phillips, Skylar Paletta, Michael Perlet","doi":"10.1080/23335432.2025.2518343","DOIUrl":"10.1080/23335432.2025.2518343","url":null,"abstract":"<p><p>Maximal voluntary isometric contractions (MVIC) are a common method to normalize electromyographic amplitude into standardized units of %MVIC. However, in 60% of drop jump research using an MVIC in 2018-2023, supramaximal activation or activation greater than 100% MVIC occurred. Therefore, MVICs may not be representative of peak muscle activation, leading to erroneous interpretation of muscle activation. The purpose of this study is to quantify EMG normalization difference in drop jump landings. Sixteen (10 M, 6F) participants were recruited for the study. MVICs were recorded from nine lower extremity muscles and this activation compared to the maximal activation recorded from 10 drop jump trials. The MVIC significantly underestimated maximum activation by 71%-140% in one-sample <i>t</i>-tests, for the rectus femoris (<i>p</i> = 0.002), vastus medialis (<i>p</i> < 0.001), medial gastrocnemius (<i>p</i> = 0.002), lateral gastrocnemius (<i>p</i> = 0.002), tibialis anterior (<i>p</i> = 0.02), and gluteus maximus (<i>p</i> = 0.03). The one-sample t-tests were not statistically significant for the remaining muscles with the data containing significant variability. Our data quantifies EMG normalization underestimate and supports the status in the literature where normalization with MVICs will underestimate maximal muscle activation in drop jump movements.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"12 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12152988/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144259400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ana Flávia Medeiros Ribeiro, Renato de Souza Melo, Daniela Cristina Rodrigues Carvalho, Juliana Fernandes, Saulo Fernandes Melo de Oliveira, Rafaella de Andrade Monteiro, Andressa da Silva de Mello, Caroline de Cássia Batista de Souza, Maria Julia de Lyra Cardoso, Maria Das Graças Rodrigues de Araújo, Ana Paula de Lima Ferreira
{"title":"Profile of para athletes and characterization of sports injuries during the 2023 Paralympic School Games.","authors":"Ana Flávia Medeiros Ribeiro, Renato de Souza Melo, Daniela Cristina Rodrigues Carvalho, Juliana Fernandes, Saulo Fernandes Melo de Oliveira, Rafaella de Andrade Monteiro, Andressa da Silva de Mello, Caroline de Cássia Batista de Souza, Maria Julia de Lyra Cardoso, Maria Das Graças Rodrigues de Araújo, Ana Paula de Lima Ferreira","doi":"10.1080/23335432.2025.2531944","DOIUrl":"10.1080/23335432.2025.2531944","url":null,"abstract":"<p><p>This article explores the characterization of sports injuries among young athletes participating in the 2023 Paralympic School Games. Injuries during the physiological growth phase can not only compromise the development of sports skills but also harm the physical development expected for their age group. Adaptive mechanisms to training are the main determinants of the location of injuries, traumas and musculoskeletal complaints. This paper aimed to identify occurrence of sports injuries in para athletes during the 2023 School Paralympics. The study population consisted of students who participated in the national stage of the 2023 School Paralympics, held at the Paralympic Training Center in the state of São Paulo. The sample consisted of 640 para-athletes, 253 (60.5%) females and 387 (60.5%) males, with an average age of 14.06 years. Overall, 14.9% of the participants reported injuries/illness. The team with the highest percentage of injured members was from the state of Tocantins (14.8%). Most of the injured athletes had intellectual disabilities (41.46%), practiced athletics (56.9%) and were in the final years of elementary school (21.95%), with an average age of 14.56 years, and the majority were male (56.86%).</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"12 1","pages":"7-17"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12269049/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144651177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sem M M Hermans, Jasper Most, Martijn G M Schotanus, Henk van Santbrink, Inez Curfs, Wouter L W van Hemert
{"title":"Accelerometer-based daily physical activity monitoring in patients with postpartum sacroiliac joint dysfunction: a case-control study.","authors":"Sem M M Hermans, Jasper Most, Martijn G M Schotanus, Henk van Santbrink, Inez Curfs, Wouter L W van Hemert","doi":"10.1080/23335432.2024.2396277","DOIUrl":"10.1080/23335432.2024.2396277","url":null,"abstract":"<p><p>Patients with low back pain caused by sacroiliac joint (SIJ) dysfunction have an impaired quality of life, due to reported pain, disability and activity limitations. There is increasing evidence that minimally invasive sacroiliac joint fusion (MISJF) results in improvement in pain, disability and quality of life in these patients. Some studies have reported improvements in daily physical activity following MISJF but based on bias-prone self-reports. Our aim was to provide objective data on daily physical activity in patients with SIJ dysfunction. Daily physical activity in daily life of participants was measured using a triaxial accelerometer for seven consecutive days, before surgery and 3 months after surgery. Recorded daily activities were the daily number of events and total time spent sitting or lying, standing, walking, cycling, high-activity and number of steps and sit-to-stand transfers. The quality of life was assessed by the validated Dutch EQ-5D-5 L-questionnaire. No statistical differences were observed between daily physical activity in patients with SIJ dysfunction before and 3 months after MISJF. As compared to matched controls, high-intensity physical activity was lower in both the pre- and postoperative period (<i>p</i> = 0.007) for patients with SIJ dysfunction. The quality of life improved significantly in patients after MSIJF, from 0.418 to 0.797 (<i>p</i> = 0.021) but did not reach the level of controls (1.000). Daily physical activity in patients with postpartum SIJ dysfunction does not improve 3 months following MISJF, while quality of life does improve significantly. The discrepancy between these two observations is food for new research.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"11 1","pages":"6-11"},"PeriodicalIF":0.0,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11382714/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142146860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alan Eldridge, Everett Lohman, Skulpan Asavasopon, Lida Gharibvand, Lori Michener
{"title":"External handheld loads affect scapular elevation and upward rotation during shoulder elevation tasks.","authors":"Alan Eldridge, Everett Lohman, Skulpan Asavasopon, Lida Gharibvand, Lori Michener","doi":"10.1080/23335432.2024.2332212","DOIUrl":"10.1080/23335432.2024.2332212","url":null,"abstract":"<p><p>Altered scapular kinematics is associated with shoulder pain. Resistance exercise is a common treatment; however, the effects of lifting an external load on scapular kinematics is limited. Understanding whether an external handheld load affects scapular kinematics in a healthy population can provide normal values utilized for comparison to individuals with shoulder pain. Currently, no studies have examined the effect of incrementally increased handheld loads. We defined the effects of varying external handheld loads on scapular kinematics during a shoulder elevation task. Healthy participants (<i>n</i> = 50) elevated their shoulder in the scapular plane over 4 trials. One trial of no loading (control) and 3 trials with incrementally increased external handheld loads. Scapular kinematic rotations and translations were measured during ascent and descent phases using 3D motion capture. Compared to no load, the highest external load during ascent increased scapular elevation [mean difference = 3.2 degrees (95%CI: 0.9, 5.4), <i>p</i> = 0.006], and during descent increased scapular elevation [mean difference = 3.9 degrees (95%CI: 2.8, 5.1), <i>p</i> < 0.001] and increased <b>scapular upward rotation</b> [mean difference = 4.5 degrees (95%CI: 2.4, 6.6), <i>p</i> < 0.001]. External handheld loads result in small <b>increases in scapular elevation and scapular upward rotation</b>. These results should be utilized as normal values to compare to individuals with shoulder pain.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"11 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10953777/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140159563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Is larger eccentric utilization ratio associated with poorer rate of force development in squat jump? An exploratory study","authors":"Ž. Kozinc, Darjan Smajla, N. Šarabon","doi":"10.1080/23335432.2024.2341634","DOIUrl":"https://doi.org/10.1080/23335432.2024.2341634","url":null,"abstract":"ABSTRACT This exploratory study examines the relationship between the eccentric utilization ratio (EUR) and the rate of force development (RFD) in squat jumps (SJ). EUR, a key metric in sports science, compares performance in countermovement jumps (CMJ) and squat jumps (SJ). The study hypothesizes that a higher EUR is associated with a poorer RFD in SJ. Basketball and soccer players, long-distance runners, alongside physical education students (209 men; age: 23.2 ± 4.95 years and 104 women; age: 22.7 ± 4.42 years) participated. The EUR was calculated from jump height, peak force and peak power. The results indicated a small to moderate but significant negative correlation between EUR based on peak force or peak power and RFD in SJ (r = –.41 and −.27), suggesting that a higher EUR might be linked to a diminished ability to rapidly develop force in SJ. Thus, a higher EUR may not indicate superior athletic performance.","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"18 S24","pages":"1 - 5"},"PeriodicalIF":0.0,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140708333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Donna Moxley Scarborough, Shannon E Linderman, Ryan Aspenleiter, Eric M Berkson
{"title":"Quantifying muscle contraction with a conductive electroactive polymer sensor: introduction to a novel surface mechanomyography device.","authors":"Donna Moxley Scarborough, Shannon E Linderman, Ryan Aspenleiter, Eric M Berkson","doi":"10.1080/23335432.2024.2319068","DOIUrl":"10.1080/23335432.2024.2319068","url":null,"abstract":"<p><p>Clinicians seek an accurate method to assess muscle contractility during activities to better guide treatment. We investigated application of a conductive electroactive polymer sensor as a novel wearable surface mechanomyography (sMMG) sensor for quantifying muscle contractility. The radial displacement of a muscle during a contraction is detected by the physically stretched dielectric elastomer component of the sMMG sensor which quantifies the changes in capacitance. The duration of muscle activation times for quadriceps, hamstrings, and gastrocnemius muscles demonstrated strong correlation between sMMG and EMG during a parallel squat activity and isometric contractions. A moderate to strong correlation was demonstrated between the sMMG isometric muscle activation times and force output times from a dynamometer. The potential wearable application of an electroactive polymer sensor to measure muscle contraction time is supported.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"10 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10906126/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139991794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fatigue behavior of three thin CAD/CAM all-ceramic crown materials.","authors":"Khaled Bataineh, Mohammad Al Janaideh","doi":"10.1080/23335432.2024.2303121","DOIUrl":"10.1080/23335432.2024.2303121","url":null,"abstract":"<p><p>The purpose of this study was to study the effect of crown thickness on the fatigue life of CAD/CAM ceramic materials. CAD/CAM ceramic materials for the crown were virtually designed with three thickness designs of (a) ultra-thin occlusal crown average 0.7 mm thick (group A), (b) thin occlusal crown 1.1 mm average thick (group B), (c) thick occlusal crown 1.5 mm thick. The materials are: zirconia Cercon ZC and IPS e.max CAD (LD). Finite Element Analysis (FEA) simulations were carried out to estimate the fatigue lives of restorative materials. The lives for groups B and C under fatigue load were not significantly different from each other for Zirconia. The predicted lives for group A zirconia crowns, under fatigue load 50 N, 100 N, 120 N is 24 years, 4.3 years, 1.9 years, respectively. Results for crowns made of LD can be summarized as follows: under load 50 N, all groups have survived longer than 5 respectively, while under the load of 100 N, only group C survived longer than 5 years. 0.7 mm thick full contour Zirconia crowns possessed adequate endurance strength to survive under physiologic conditions. On the other hand, the crown made of LD should have at least 1.5 mm thickness to survive longer than 5 years.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"10 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10786422/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139418495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Use of adult anthropometric tables to estimate children body segment inertial parameters.","authors":"Sabrina Otmani, Guilhem Michon, Bruno Watier","doi":"10.1080/23335432.2023.2268686","DOIUrl":"10.1080/23335432.2023.2268686","url":null,"abstract":"<p><p>There is a lack of knowledge in the literature concerning Body Segment Inertial Parameters (BSIP) for children aged 4 to 15 years. Nevertheless, these data are fundamental for studying the dynamics of the healthy and pathological musculoskeletal system. One common method for obtaining BSIP is to use regression equations derived from anthropometric tables. However, the majority of these equations are based on adult data. In this study, we compared certain BSIP (segment mass, center of mass position, and transverse moment of inertia) derived from adult anthropometric tables with the corresponding BSIP extracted from a pediatric anthropometric table. The goal of this study was to determine the accuracy of using adult anthropometric tables to calculate pediatric BSIP. For this comparison, we assessed the proximity of several adult anthropometric tables to a pediatric anthropometric table by Jensen (1986) for each BSIP. Our results revealed differences between the BSIP obtained using adult tables and the BSIP obtained with the pediatric table used as a reference. When considering all the tables, the mean relative difference was 12% for segment mass, 12% for center of mass position, and 25% for transverse moment of inertia. Notably, the greatest relative differences were observed for the head, hand, and foot segments. Additionally, the relative difference in female data was higher compared to males. This result could be attributed to the predominant use of male subjects in the adult tables considered in this study. Finally, the adult anthropometric tables by Dumas and Wojtsuch (2018) and De Leva (1996) provided results that were closer in comparison to Jensen (1986).</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":"10 1","pages":"18-28"},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11072689/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138447058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Toni Wendler, Benjamin Fischer, Alexander Brand, Martin Weidling, Johannes Fakler, Dirk Zajonz, Georg Osterhoff
{"title":"Biomechanical testing of different fixation techniques for intraoperative proximal femur fractures: a technical note.","authors":"Toni Wendler, Benjamin Fischer, Alexander Brand, Martin Weidling, Johannes Fakler, Dirk Zajonz, Georg Osterhoff","doi":"10.1080/23335432.2022.2142159","DOIUrl":"https://doi.org/10.1080/23335432.2022.2142159","url":null,"abstract":"<p><p>Intraoperative proximal femoral fractures (IPFF) represent a rare but challenging complication of total hip arthroplasties. They usually occur as a longitudinal split. This pilot trial aimed to compare the biomechanical primary stability of different fixation techniques for IPFF. Standardised longitudinal medial split fractures of the proximal femur (type II, Modified Mallory Classification) were created in artificial osteoporotic and non-osteoporotic composite femora after implantation of a cementless femoral stem. Five different fixation techniques were compared: cerclage band, cerclage wiring with one or two wires, and lag screw fixation with one or two lag screws. A quasi-static loading protocol was applied and failure loads were evaluated. The observed median failure loads were 4192N (3982N - 5189N) for one cerclage band, 4450N (3577N - 4927N) for one cerclage wire, 5016N (4175N - 5685N) for two cerclage wires, 6085N (5000N - 8907N) for one lag screw, and 4774N (4509N - 8502N) for two lag screws. Due to the wide range of failure loads within the experimental groups, there were no observable differences between the groups. All fixation techniques provided sufficient primary stability in osteoporotic and non-osteoporotic composite bones. Further cadaveric studies with larger sample sizes may be needed to confirm the results presented here.</p>","PeriodicalId":52124,"journal":{"name":"International Biomechanics","volume":" ","pages":"27-32"},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9683064/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40697106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}