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Human limb surrogates, of varying biofidelity, are used in the performance assessment of sports personal protective equipment (PPE). Such biofidelic surrogates have incorporated soft tissue simulants (silicones) and synthetic bone (short fibre filled epoxy). Testing surrogates incorporating realistic synthetic bone could help to further our knowledge of fracture trauma mechanics, and applications such as the effectiveness of sports PPE. Limb surrogates with embedded synthetic bone are rarely tested to fracture, mainly due to the effort and cost of replacing them. This paper proposes additive manufacturing of synthetic bones, with appropriate bone like fracture characteristics, potentially making them more accessible and cost effective. A Markforged® X7™ printer was used as it prints a base filament (Onyx™) alongside a continuous strand of reinforcement (e.g., carbon fibre). The properties of specimens from this printer vary with the type, volume fraction and position of reinforcement. Bar specimens (10 × 4 × 120 mm) with varying amounts of carbon fibre reinforcement were printed for three-point bend testing to determine the feasibility of achieving mechanical properties close to compact bone (bending modulus of ∼15 GPa, bending strength of ∼180 MPa). Bending strength for the various bar specimens ranged from 32 to 378 MPa, and modulus values ranged from 1.5 to 25.8 GPa. Based on these results, four 140 mm long oval shaped cylindrical specimens of ø14 and ø16 mm were printed to represent a basic radius bone model. Three-point bend testing of these bone models showed similar bending modulus (3.8 to 5.3 GPa vs. 3.66 to 14.8 GPa) to radius bones reported in the literature, but higher bending strength (147 to 200 MPa vs. 80.31 ± 14.55 MPa).

Background Eumenorrheic women experience cyclic variations in sex hormones attributed to the menstrual cycle (MC) which can impact anterior cruciate ligament (ACL) properties, knee laxity, and neuromuscular function. This systematic review aimed to examine the effects of the MC on ACL neuromuscular and biomechanical injury risk surrogates during dynamic tasks, to establish whether a particular MC phase predisposes women to greater ACL injury risk. Methods PubMed, Medline, SPORTDiscus, and Web of Science were searched (May-July 2021) for studies that investigated the effects of the MC on ACL neuromuscular and biomechanical injury risk surrogates. Inclusion criteria were: 1) injury-free women (18–40 years); 2) verified MC phases via biochemical analysis and/or ovulation kits; 3) examined neuromuscular and/or biomechanical injury risk surrogates during dynamic tasks; 4) compared ≥1 outcome measure across ≥2 defined MC phases. Results Seven of 418 articles were included. Four studies reported no significant differences in ACL injury risk surrogates between MC phases. Two studies showed evidence the mid-luteal phase may predispose women to greater risk of non-contact ACL injury. Three studies reported knee laxity fluctuated across the MC; two of which demonstrated MC attributed changes in knee laxity were associated with changes in knee joint loading (KJL). Study quality (Modified Downs and Black Checklist score: 7–9) and quality of evidence were low to very low (Grading of Recommendations Assessment Development and Evaluation: very low). Conclusion It is inconclusive whether a particular MC phase predisposes women to greater non-contact ACL injury risk based on neuromuscular and biomechanical surrogates. Practitioners should be cautious manipulating their physical preparation, injury mitigation, and screening practises based on current evidence. Although variable (i.e., magnitude and direction), MC attributed changes in knee laxity were associated with changes in potentially hazardous KJLs. Monitoring knee laxity could therefore be a viable strategy to infer possible ACL injury risk.

Introduction Performing contractions with minimum force fluctuations is essential for everyday life as reduced force steadiness impacts on the precision of voluntary movements and functional ability. Several studies have investigated the effect of experimental or clinical musculoskeletal pain on force steadiness but with conflicting findings. The aim of this systematic review is to summarise the current literature to determine whether pain, whether it be clinical or experimental, influences force steadiness.Methods and analysis This protocol for a systematic review was informed and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols and the Cochrane Handbook for Systematic Reviews of Interventions. Key databases will be searched from inception to 31 August 2020, including MEDLINE, EMBASE, PubMed, CINAHL Plus, ZETOC and Web of Science. Grey literature and key journals will be also reviewed. Risk of bias will be assessed with the Newcastle-Ottawa tool, and the quality of the cumulative evidence assessed with the Grading of Recommendations, Assessment, Development and Evaluation guidelines. If homogeneity exists between groups of studies, meta-analysis will be conducted. Otherwise, a narrative synthesis approach and a vote-counting method will be used, while the results will be presented as net increases or decreases of force steadiness.Ethics and dissemination The findings will be presented at conferences and the review will be also submitted for publication in a refereed journal. No ethical approval was required.PROSPERO registration number CRD42020196479

Introduction Chronic, non-specific low back pain is a major global cause of disability. One factor which might potentially contribute to ongoing pain is maladaptive variation in the level of activity in the lumbar musculature. Several studies have investigated this activity using surface electromyography, in varied muscles and during a number of functional activities. Due to differences in the applied methodology, the results have been difficult to compare, and previous reviews have been limited in scope. In this protocol, we aim to perform a comprehensive review of the effect of chronic low back pain on lumbar muscle activity.Methods and analysis This protocol was informed by the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) and results will be reported in line with the PRISMA. Searches will be conducted on the Web of Science, PubMed, MEDLINE, EMBASE, ZETOC and CINAHL databases, along with a comprehensive review of grey literature and key journals. One reviewer will conduct the searches, but two independent reviewers will screen potential studies and assess the risk of bias within studies which meet the inclusion criteria. The Newcastle-Ottawa risk of bias tool, and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) guidelines will be used to assess the quality of the data. Meta-analysis will be conducted where appropriate on groups of studies with homogenous methodology. Where studies are too heterogeneous to allow for meta-analysis, meta-synthesis will instead be completed, comparing results in terms of net increases or decreases of activity.Ethics and dissemination This review aims to identify common adaptations of muscle activity in people with low back pain and it is expected that the results will influence future research directions and future rehabilitation approaches. The results will be submitted for publication in a peer-reviewed journal and presented at conferences.Prospero registration number CRD42019125156