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Background: Conventional muscle biopsy techniques, such as the Bergström method, require large tissue samples and skin incisions. Fine-needle muscle microbiopsy offers a minimally invasive alternative, but data on tolerability are lacking. We aimed to present a refined minimally-invasive muscle microbiopsy protocol using a 20-gauge needle with topical anaesthesia and compare perceived pain with routine venipuncture.

Methods: Twenty-six healthy adults (50% female) underwent vastus lateralis microbiopsy using a 20-gauge needle (0.9 mm). Pain was assessed immediately after the microbiopsy and a venous blood draw using a 21-gauge needle, with the visual analogue scale (VAS). Procedures were randomized.

Results: Seventy-eight microbiopsies were successfully obtained. Mean pain scores were low for both procedures (microbiopsy: 1.0 ± 0.9; venipuncture: 1.4 ± 1.2) with no significant difference (P = 0.311). Most participants reported minimal or low discomfort (VAS ≤3) from the microbiopsy.

Conclusion: Fine-needle muscle microbiopsy using a 20-gauge needle is well tolerated, with pain comparable to routine venipuncture. This approach substantially reduces invasiveness compared to traditional biopsies while providing adequate material for proteomic analysis. These findings support its ethical and practical application in sensitive populations and longitudinal research.

Predictors for the pharmacological effect of ADHD medication in children and adolescents are lacking. This study examined clinically relevant factors in a large (N = 638) prospective cohort reflecting real-world evidence. Children and adolescents aged 6–17 diagnosed with ADHD were evaluated at baseline and three months following ADHD medication initiation. The outcome was measured as a reduction in total SNAP-IV (Swanson Nolan and Pelham teacher and parent rating scale) score at three months compared to baseline. Outcome groups were defined as Responders (≥ 40% reduction), Intermediate Responders (≥ 20 to < 40% reduction), and Non-responders (< 20% reduction). Included independent variables were the Autism Spectrum Questionnaire (ASSQ), the Spence Children’s Anxiety Scale (SCAS), the Pediatric Side Effect Checklist (P-SEC), anthropometrics measures, geographical region, relative age, Children´s Global Assessment Scale (CGAS), Intelligence quotient (IQ), pharmacological treatment initiation month, ADHD symptom severity, ADHD presentation, and psychotic-like experiences. Multinomial logistic regression suggested that ADHD symptom severity, region, relative age, and stating ADHD medication at three-month follow-up were associated with the response outcome group. However, when validating the data with Bootstrap Forest, none of the variables were significant. Thus, in our large naturalistic cohort, we could not identify any clinically relevant factors that reliably predict pharmacological treatment outcomes.

Objective: Rheumatoid arthritis (RA) is a common chronic systemic inflammatory disease that causes musculoskeletal impairments and fatigue. Physical activity is recommended for individuals with RA, and health-enhancing physical activity (HEPA) has been shown to improve health perception and physical fitness in this group. However, the molecular adaptations of skeletal muscle in response to an exercise intervention are still unexplored in individuals with RA. This study aimed to assess the skeletal muscle response to a 2-year HEPA intervention in individuals with RA.

Methods: Thirteen individuals with RA (65 ± 2 years old, 13 ± 2 years disease duration) participated. The 2-year HEPA intervention involved 150 min of weekly moderately intense aerobic activity and twice-weekly circuit training. Practical and theoretical physiotherapist support was available the first year, but not the second year. Skeletal muscle biopsies, functional assessments, and mass spectrometry-based proteomics analysis were conducted.

Results: Compliance was high the first year but dropped significantly the second year. Functional improvements in strength, endurance, and lower extremity muscle function (TST) were observed after year 1. Proteomics analysis revealed significant enrichment of mitochondrial proteins including COX8A, citrate synthase, M2OM, NDUFA6, NDUFS2, and VDAC3 after year 1, indicating positive muscle adaptations. However, these changes regressed to baseline levels by year 2.

Conclusion: HEPA can induce beneficial mitochondrial adaptations in skeletal muscle of individuals with RA. However, insufficient compliance and progression in HEPA exercise load led to a reversal of these adaptations. Continuous support and motivation are crucial for maintaining and progressing exercise levels and muscle health in individuals with RA. (Table presented.)

Introduction: Predicting competitive alpine skiing performance using conventional statistical methods has proven challenging. Many studies assessing the relationship between physiological performance and skiing outcomes have employed statistical methods of questionable validity. Furthermore, the reliance on Fédération Internationale de Ski (FIS) points as a performance outcome variable presents additional limitations due to its potential unreliability in reflecting short-term, sport-specific performance. These factors complicate the selection of appropriate tests and the accurate prediction of competitive outcomes.

Method: This study aimed to evaluate the predictive power of a generalized physiological test battery for alpine skiing performance, as measured by FIS points, utilizing multivariable data analysis (MVDA). Physiological test results from a total of twelve (n = 12) world-class female skiers were included in the analysis.

Results: The result on goodness of regression (R2) and goodness of prediction (Q2) in this study indicate that valid Orthogonal Projection to Latent Structures (OPLS) models for both Slalom and Giant Slalom can be generated (R2 = 0.39 to 0.40, Q2 = 0.21 to 0.15), but also that competition performance still cannot be predicted at a group level (low Q2). In contrast, higher predictive power of competitive performance was achieved on an individual level using the same data (R2 = 0.88 to 0.99 and Q2 = 0.64 to 0.96).

Discussion: The findings of this investigation indicate that the selected tests employed in this study exhibit limited generalizability for the assessment of elite alpine skiers, as the predictive value of specific physiological parameters on competitive performance appears to be highly athlete-dependent.

Background: The relative age effect (RAE) is a worldwide phenomenon, allowing sport participation and elite selection to be based on birthdate distribution. Negative consequences include both a narrow, non-optimal elite selection and negative health effects on entire populations. This study investigated the RAE and athletic performance in multiple individual sports in Sweden. Methods: Birthdates of athletes born between the years 1922 and 2015 were collected across 4-month periods (tertiles: T1, T2, T3) from cross-country skiing (N = 136,387), orienteering (N = 41,164), athletics (N = 14,503), alpine skiing (N = 508), E-sports (N = 47,030), and chess (N = 4889). In total, data from 244,560 athletes (women: N = 79,807, men: N = 164,753) was compared to the complete parent population of 5,390,954 births in Sweden during the same years. Chi-squared statistics compared parent and cohort distributions stratified by sport, sex, and age. Results: A significantly skewed distribution of birthdates was present in all sports, both sexes, and most age groups. The largest RAEs are seen in children where T1 often constitutes 40–50% and T3, 20–25% of the population. In E-sports, an inversed RAE was seen in adults. In most investigated sports, birthdate distribution was correlated to performance in children but not in adults. Conclusions: Skewed birthdate distributions were consistently prevalent in all investigated individual sports in Sweden, both physically demanding and cognitive/skill-based. As sport participation is related to total level of physical activity, both present and future, failing to address the RAE issue at an early age will result not only in a narrow and arbitrary selection for adult elite athletes but also in a negative impact on public health.

Resistance exercise has been shown to induce an acute hormonal response. The purpose of this study was to examine upper-body adaptations and the endocrine response to strength training in men and women when subjected to two different types of lower-body resistance training protocols. Nine males and eight females were assigned to either a Heavy Load (HL) (N = 10) or Mixed Load (ML) (N = 7) training routine three times per week for ten weeks. The HL-group executed low-volume, high-load resistance exercise for both lower and upper-body (4-6 reps at 80-90% of one repetition maximum (1-RM), three-minute inter-set rest). The ML-group performed the HL-protocol for the upper-body, but a high-volume, moderate-load protocol for the lower body (10-15 reps at 60-70% of 1-RM, one-minute inter-set rest). Volume load, 1-RM strength and hormonal measurements were analyzed by repeated-measures linear mixed models. Both groups increased their 1-RM in all assessments (p < 0.01) with no significant difference between groups at any time. Growth hormone (GH), testosterone and bioavailable testosterone (T/SHBG) increased in both groups during a standardized exercise session (p < 0.01) with ML having a greater increase in GH. The notion that acute elevations in anabolic hormones is important for muscle strength adaptation cannot be supported by the present study.

Competitive alpine skiing is a complex sport that requires high physical and technical competence. Testing the physical status of athletes may be important to increase their ability to achieve elite sport-specific performance. This study aimed to investigate the predictive power of the national test battery of the Swedish Olympic Committee (Fysprofilen) and anthropometric variables in the prediction of competitive performance of elite alpine skiers, indicated by Fédération Internationale de Ski points. Data from fourteen Swedish elite female alpine skiers were analyzed using bivariate and multivariate statistical methods. Physiological test results and anthropometric data could not generate significant bivariate or multivariate models for prediction of competitive performance. Multivariate regression (R2) and prediction (Q2) models for Fédération Internationale de Ski Slalom and Giant Slalom rank reached R2=0.27 to 0.43, Q2=+− 0.8 to−0.17, indicating no valid models. The overall interpretation of these and previous findings are that future test batteries must be validated before implemented, and that test results should be treated with caution when it comes to prediction of future competitive results. Applying tests that are not validated against competitive performance risk misleading coaches and training advisors who aim to increase the sports-specific performance of the individual athlete.

Multiple sclerosis (MS) is a neurodegenerative disease of the central nervous system. The animal model of MS, experimental autoimmune encephalomyelitis (EAE), is commonly used for studies of human inflammatory demyelinating diseases and has been shown to be suitable for studying the effects of exercise on MS pathophysiology. The present study was conducted to determine the impact of forced swimming and voluntary running wheel exercises before and after the induction of EAE on expression of Nogo-A, NgR, and ROCK genes in the brain tissue. A total of 96 C57BL/6 mice were randomly divided into two groups, namely exercises before (EXb, n = 48) and after (EXa, n = 48) induction of EAE. Each group was divided into four subgroups: Forced Swimming + EAE (n = 12), Voluntary Running Wheel + EAE (n = 12), NoEX-EAE (n = 12), and Control group (n = 12). Animals performed either swimming exercise for 30 min per day or running wheel for one hour per day, five days per week for four weeks. Results of Luxal Fast Blue (LFB) staining demonstrated that the degree of demyelination was significantly less in the experimental exercised compared to NoEX-EAE groups (P < .05). Amazingly, both modes of exercise reduced the severity of MS symptoms in mice exposed to swimming and wheel running, evaluated as body weight, clinical scores, degree of demyelination, and gene expressions, regardless of whether the exercise was performed before or after EAE induction.

BACKGROUND AND OBJECTIVES: Red-blood-cells (RBCs) undergo structural and metabolic changes with prolonged storage, which ultimately may decrease their survival after transfusion. Although the storage-induced damage to RBCs has been rather well described biochemically, little is known about the mechanisms underlying the recognition and rapid clearance of the damaged cells by macrophages.

MATERIALS AND METHODS: We, here, used a murine model for cold (+4°C) RBC storage and transfusion. Phagocytosis of human or murine RBCs, liquid stored for 6-8 weeks or 10-14 days, respectively, was investigated in murine peritoneal macrophages.

RESULTS: The effects of storage on murine RBCs resembled that described for stored human RBCs with regard to decreased adenosine triphosphate (ATP) levels, accumulation of microparticles (MPs) during storage, and RBC recovery kinetics after transfusion. Under serum-free conditions, phagocytosis of stored human or murine RBCs in vitro was reduced by 70-75%, as compared with that in the presence of heat-inactivated fetal calf serum (FCS). Human serum promoted phagocytosis of stored human RBCs similar to that seen with FCS. By adding fucoidan or dextran sulphate (blockers of scavenger receptors class A (SR-A)), phagocytosis of human or murine RBCs was reduced by more than 90%. Phagocytosis of stored human RBCs was also sensitive to inhibition by the phosphatidylinositol 3 kinase-inhibitor LY294002, the ERK1/2-inhibitor PD98059, or the p38 MAPK-inhibitor SB203580.

CONCLUSION: RBCs damaged during liquid storage may be recognized by macrophage SR-A and serum-dependent mechanisms. This species-independent recognition mechanism may help to further understand the rapid clearance of stored RBCs shortly after transfusion.