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Purpose: Examine the acute hormonal and cytokine responses to free-weight resistance training in trained prepubertal and pubertal male children.

Methods: Prepubertal (n = 21; age 11.4 ± 1.1 years; Tanner I–II) and pubertal male children (n = 20; age 15.8 ± 0.7 years; Tanner III–V) conducted a moderate-intensity free-weight resistance training program to failure with venous blood sampling before (pre), immediately after (post) and during the recovery phase of the program (post-15,-30 min). Growth hormone (GH), insulin-like growth factor-I (IGF-I), cortisol, testosterone, IL-6, and TNF-α were analyzed in serum samples. Biological maturation was assessed according to the stages of the Tanner scale.

Results: There was a significant time-by-group interaction in IGF-I response (p = 0.044; η2 = 0.209) and testosterone (p < 0.001; η2 = 0.508), indicating a greater change in the pubertal group compared to the prepubertal group. Both groups significantly increased post-exercise GH levels (p < 0.05). Only the prepuberal group significantly increased levels of IL-6 at all post-exercise time points (p < 0.05). Both groups showed a significant (p < 0.05) increase in TNF-α levels compared to resting levels.

Conclusion: These data suggest that acute testosterone and IGF-I response following resistance training differ between trained prepubertal and pubertal male children. Moderate-intensity resistance training performed to failure may thus have different effects in trained prepubertal and pubertal male children, which should be considered when giving training advice. Trial registration: Clinical trials number: NCT05022992.

Background: No previous systematic review has quantitatively compared the effects of resistance training, endurance training, or concurrent training on hormonal adaptations in children and adolescents. Objective was to examine the effects of exercise training and training type on hormonal adaptations in children and adolescents.

Methods: A systematic literature search was conducted in the following databases: PubMed, Web of Science, and EBSCO. Eligibility criteria were: population: healthy youth population sample (mean age < 18 years); intervention: resistance training, endurance training, or concurrent training (> 4 weeks duration); comparison: control group; outcome: pre- and post-levels of hormones and cytokines; and study design: randomized and non-randomized controlled trials. We used a random-effect model for the meta-analysis. The raw mean difference in hormones from baseline to post-intervention was presented alongside 95% confidence intervals (CI). Further, the certainty of evidence quality and the risk of bias were assessed.

Results: A total of 3689 records were identified, of which 14 studies were eligible for inclusion. Most studies examined adolescents with fewer studies on children (age < 12 years, N = 5 studies) and females (N = 2 studies). Nine exercise training programs used endurance training, five studies used resistance training, and no eligible study used concurrent training. The meta-analysis showed no significant effect of exercise training on testosterone (MD = 0.84 nmol/L), cortisol (MD = − 17.4 nmol/L), or SHBG (MD = − 5.58 nmol/L). Subgroup analysis showed that resistance training significantly increased testosterone levels after training (MD = 3.42 nmol/L) which was not observed after endurance training (MD = − 0.01 nmol/L). No other outcome differed between training types. Exercise training resulted in small and non-significant changes in GH (MD = 0.48 ng/mL, p = 0.06) and IGF-I (MD = − 22.90 ng/mL, p = 0.07). GH response to endurance training may be age-dependent and evident in adolescents (MD = 0.59 ng/mL, p = 0.04) but not when children and adolescents are pooled (MD = 0.48 ng/mL, p = 0.06). Limited evidence exists to conclude on IL-6 and TNF-α effects of exercise training. Assessments of GRADE domains (risk of bias, consistency, directness, or precision of the findings) revealed serious weaknesses with most of the included outcomes (hormones and cytokines).

Conclusions: This systematic review suggests that exercise training has small effects on hormonal concentrations in children and adolescents. Changes in testosterone concentrations with training are evident after resistance training but not endurance training. GH's response to training may be affected by maturation and evident in adolescents but not children. Further high-quality, robust training studies on the effect of resistance training, endurance training, and concurrent training are warranted to compare their training-specific effects.

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.

Background: The Swedish National Airway Register (SNAR) was initiated to improve and ensure quality of care for patients with asthma and COPD.

Aim: To describe the register design of SNAR and unique patients between the years of 2014 until 2019.

Methods: SNAR has been ongoing since 2013 and includes patients with asthma (both children and adults) and COPD from primary and secondary care (both in- and outpatients). Data about healthcare provider, symptoms, comorbidities, additional investigations (i.e. spirometry) and prescribed treatment is registered. The registrations are performed manually by healthcare professionals, or directly transmitted from medical records to a web-based platform.

Results: In 2019, 853 primary care clinics, 125 secondary care clinics (whereof 62 pediatric clinics) and 24 inpatient wards were linked to the register. Data was directly transmitted from medical records of about 80% of the clinics, and manually by 20%. The register includes in total 205833 unique patients with asthma and 80372 with COPD. Registrations of new patients and follow-up visits in 2019 applied 73788 patients with asthma (58% women, mean age 44yr) whereof 10190 were <11yr and 6248 were 12-17yr, 33276 with COPD (57% women, mean age 73yr), and 5013 with both asthma and COPD (ACO) (61% women, mean age 71yr). In COPD, the proportion of patients in GOLD 1-4 were; GOLD1 15%, GOLD2 55%, GOLD3 25% GOLD4 5%. During 2019, 1506 registered patients with asthma and 3791 with COPD died.

Conclusion: The SNAR has cumulatively registered over 280000 individuals and provides a unique insight into the care of patients with asthma and COPD in Sweden.

The aim of this study was to investigate the predictive power of aerobic test results and anthropometric variables on FIS-ranking of junior elite alpine skiers. Results from twenty-three male and female adolescent elite alpine skiers from two seasons were included in the multivariate statistical models. Physical work capacity was determined by V̇O2peak, blood lactate concentration ([HLa]b), and heart rate (HR) during ergometer cycling. Anthropometric variables were body stature, body weight and calculated BMI. No significant correlation between competitive performance and aerobic work capacity or anthropometric data was observed neither in male nor female adolescent skiers. Pre-season physical tests and anthropometric data could therefore not predict end-season FIS-ranking. The best regression (R2) and prediction (Q2) models of FIS slalom (SL) and giant slalom (GS) rank reached R2=0.51 to 0.86, Q2=−0.73 to 0.18, indicating no valid models. This study could not establish V̇O2peak and other included variables as predictors of competitive performance. When combining results from commonly used tests for alpine skiers, and applying multivariate statistical models, investigated tests seems of limited used for athletes, coaches, and ski federations. Performance-specific pre-season tests must be developed and validated for prediction of performance and guidance of exercise training.

Physical capacity has previously been deemed important for firefighters physical work capacity, and aerobic fitness, muscular strength, and muscular endurance are the most frequently investigated parameters of importance. Traditionally, bivariate and multivariate linear regression statistics have been used to study relationships between physical capacities and work capacities among firefighters. An alternative way to handle datasets consisting of numerous correlated variables is to use multivariate projection analyses, such as Orthogonal Projection to Latent Structures. The first aim of the present study was to evaluate the prediction and predictive power of field and laboratory tests, respectively, on firefighters’ physical work capacity on selected work tasks. Also, to study if valid predictions could be achieved without anthropometric data. The second aim was to externally validate selected models. The third aim was to validate selected models on firefighters’ and on civilians’. A total of 38 (26 men and 12 women) + 90 (38 men and 52 women) subjects were included in the models and the external validation, respectively. The best prediction (R2) and predictive power (Q2) of Stairs, Pulling, Demolition, Terrain, and Rescue work capacities included field tests (R2 = 0.73 to 0.84, Q2 = 0.68 to 0.82). The best external validation was for Stairs work capacity (R2 = 0.80) and worst for Demolition work capacity (R2 = 0.40). In conclusion, field and laboratory tests could equally well predict physical work capacities for firefighting work tasks, and models excluding anthropometric data were valid. The predictive power was satisfactory for all included work tasks except Demolition.

The overall aim of this thesis was to identify valid, simple, and inexpensive physical tests that can be used for evaluation of firefighters’ physical work capacity. Paper I included fulltime- and part-time firefighters (n = 193), aged 20-60 years. Perceived physical demands of firefighting work tasks were ranked, and comparisons between subject groups rating were done with the Mann Whitney U-test and Binominal test. Papers II and III included male firefighters and civilian men and women (n = 38), aged 24-57 years. Laboratory and field tests of aerobic fitness, muscle strength and endurance, balance, and simulated firefighting work tasks were performed. Physical capacity comparisons between subject groups were done and bivariate correlations between physical tests and work capacity in the simulated firefighting work tasks analyzed. Paper IV included the same subjects as in Paper II-III (training-set), and additional 90 subjects (prediction-set), aged 20-50 years. Laboratory and field tests of aerobic fitness, muscle strength and endurance and balance, and simulated firefighting work tasks were included. Data from the training-set was used to build models for prediction of firefighters’ physical work capacity, using multivariate statistic. The prediction-set was used to externally validate the selected models. Several work tasks were rated as physically demanding and significant differences (p < 0.05) in ratings were found between full-time and part-time firefighters (Paper I). Significant differences were found between subject groups in physical capacity, and work capacity (p < 0.01) (Paper II-IV). Both laboratory and field tests were significantly (p < 0.01) correlated with work capacity time (Paper II-III). The prediction (R²) and predictive power (Q²) of firefighters’ work capacity (Carrying hose baskets upstairs, Hose pulling, Demolition at or after a fire, Victim rescue, and Carrying hose baskets over terrain) was R² = 0.74 to 0.91, and Q² = 0.65 to 0.85, and the external validation ranged between R²: 0.38 to 0.80 (Paper IV).

In conclusion, rowing 500 m (s), maximal handgrip strength (kg), endurance bench press (n), running 3000 m (s and s scaled to body weight) upright barbell row (n) and standing broad jump (m) together provides valid information about firefighters’ physical work capacity. 

Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = −0.81) and barbell shoulder press (rs = −0.77), for Pulling: IE shoulder extension (rs= −0.82) and bench press (rs = −0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = −0.83) and bench press (rs = −0.82), and for the Terrain work task: IE trunk flexion (rs = −0.58) and upright barbell row (rs = −0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity.

Objectives: The present study sought to identify firefighters' rated physical demands for the most frequently occuring work tasks and to determine if the ratings differed between full-time and part-time firefighters to help create a basis for the development of physical employment tests for firefighters.

Methods: An extensive questionnaire was completed by 125 and 68 firefighters in 2000 and 2010, respectively. The data were analysed with the Mann-Whitney U test and binominal test and ranked on the basis of the responses in each category.

Results: Significant differences were seen between the full-time and part-time firefighters. The work tasks rated as the most physically strenous in terms of aerobic fitness, muscle strength, work posture and body control by most responders were smoke diving upstairs (carrying a hose), victim rescue in different ways, carrying a stretcher over terrain and pulling a hose.

Conclusions: Physically strenous work tasks should be included in the end-point performance variables used to select physical performance tests for firefighters. The part-time firefighters with no experience in several of the work tasks suggests that work-related exercises are important if both groups of firefighters are expected to do similar work.

Working as a firefighter is physically strenuous, and a high level of physical fitness increases a firefighter's ability to cope with the physical stress of their profession. Direct measurements of aerobic capacity, however, are often complicated, time consuming, and expensive. The first aim of the present study was to evaluate the correlations between direct (laboratory) and indirect (field) aerobic capacity tests with common and physically demanding firefighting tasks. The second aim was to give recommendations as to which field tests may be the most useful for evaluating firefighters' aerobic work capacity. A total of 38 subjects (26 men and 12 women) were included. Two aerobic capacity tests, six field tests, and seven firefighting tasks were performed. Lactate threshold and onset of blood lactate accumulation were found to be correlated to the performance of one work task (rs = -0.65 and -0.63, p<0.01, respectively). Absolute (mL·min(-1)) and relative (mL·kg(-1)·min(-1)) maximal aerobic capacity was correlated to all but one of the work tasks (rs = -0.79 to 0.55 and -0.74 to 0.47, p<0.01, respectively). Aerobic capacity is important for firefighters' work performance, and we have concluded that the time to row 500 m, the time to run 3000 m relative to body weight (s·kg(-1)), and the percent of maximal heart rate achieved during treadmill walking are the most valid field tests for evaluating a firefighter's aerobic work capacity.