Amund Riiser

Adding/removing text In the published article (Statistical Analysis) we did not include how gender was coded. We apologies for the mistake as it makes application of the model difficult. We want to include "In the regression model females were coded as 1, and males as 2."A correction has been made to the section "Materials and Methods" sub-section "Statistical Analysis" after: "We estimated VO2max on the maximal protocol using multiple linear regression with time to RPE ≥ 17 at the submaximal protocol, age, body mass, gender, and HRmax% as independent variables."The original version of this article has been updated.We estimated VO2max on the maximal protocol using multiple linear regression with time to RPE ≥ 17 at the submaximal protocol, age, body mass, gender, and HRmax% as independent variables. In the regression model females were coded as 1, and males as 2.Adding/removing text In the published article (Results) we did not include how gender was coded. We apologies for the mistake as it makes application of the model difficult. We want to include (females coded as 1, males as 2) after "The best model for estimation of VO2max from the submaximal test was as follows: VO2max = 45.873 + (1.159 submaximal test time) + (-0.301 body mass) + (-0.264 age) + (7.627 gender).

Background: The incremental model of doping behavior (IMDB) posits that doping develops over time through the habit of using performance enhancers such as dietary supplements. We investigated the association between dietary supplement use and beliefs and doping attitudes among Norwegian sportspersons. Methods: A total of 1441 subjects (females: 44%; age 31.3 ± 11.6 years) responded to an online questionnaire including measures of dietary supplement use and beliefs, performance enhancement attitude (PEAS), and a doping likelihood vignette. Data were analyzed using descriptive statistics, correlations, and multiple regression analysis. Results: 58% used dietary supplements. Dietary supplement beliefs were positively correlated with doping attitudes (r = 0.27 (PEAS) and r = 0.16 (vignette), p < 0.001). Among non-competitive respondents, younger respondents were more likely to endorse supplement use (r = −0.08, p = 0.073 vs. r = −0.30, p < 0.001) and doping use (r = −0.17, p < 0.001 and r = −0.21, p < 0.001). Males endorsed supplement use (Welch’s t tests > 5.19, p < 0.001) and doping (Welch’s t tests > 4.08, p < 0.001) more than females. Norwegian sportspersons are generally ambivalent about dietary supplements but opposed to doping practices in sport. Results of multiple regression analysis indicated that younger, male, non-competitive, and supplement-endorsing participants were more likely to endorse doping likelihood. However, these differences were small, and participants were generally against doping. Conclusions: The associations between dietary supplement use and beliefs and doping attitudes are weak but compatible with the IMDB. The differences between groups are small; however, focusing on beliefs about dietary supplements in young, male, non-competitive persons may improve the effectiveness of anti-doping interventions.

Background: Decreasing physical activity levels present a major public health challenge. The use of e-bikes has risen substantially over the past decade, presenting a potential solution to common barriers associated with physical activity and conventional cycling. However, the intensity of e-bike commuting in real-life settings remains unknown. This study aimed to investigate the self-selected intensity and the impact of topography on intensity during regular e-bike commuting. Methods: In this cross-sectional study, oxygen consumption, power output, heart rate, perceived exertion, and positional data were recorded from 19 commuters [mean (standard deviation) age 41 (8) years] during their regular commutes on their own e-bikes. Data were summarized and analyzed in 10, 30, and 60 s epochs, and adjusted for the duration of the commutes. Intensity of the commutes was compared between downhill, flat, or uphill segments using linear mixed models. The intensity of physical activity was defined as light p < 0.001). Conclusions: Our findings suggest that e-bike commuters self-selected moderate to vigorous intensities during real-life commutes, aligning with international physical activity guidelines for improving public health. Therefore, policies promoting a shift from car use to e-biking could have significant public health benefits.

Introduction: This systematic review with meta-analysis investigates the effect of glucocorticoids on maximal and submaximal performance in healthy subjects.Methods: We searched for randomised controlled trials investigating the effect of glucocorticoids on physical performance in Web of Science, Scopus, Medline, Embase and SportDiscus in March 2021. Risk of bias was assessed with the revised Cochrane Collaboration Risk of Bias Tool (RoB2). Data from random effect models are presented as standardized difference in mean (SDM) with 95% confidence interval. We included 15 studies comprising 175 subjects.Results: Two studies had high risk of bias. Glucocorticoids had a small positive effect on maximal physical performance compared to placebo (SDM 0.300, 95% CI 0.080 to 0.520) and the SDM for the 13 included comparisons was not heterogeneous (I2= 35%, p = 0.099). Meta regression found no difference in the effect of acute treatment vs. prolonged treatment or oral ingestion vs. inhalation (p > 0.124). In stratified analysis prolonged treatment (SDM 0.428, 95% CI 0.148 to 0.709) and oral ingestion (SDM 0.361, 95% CI 0.124 to 0.598) improved physical performance. Glucocorticoids improved aerobic performance (SDM 0.371, 95% CI 0.173 to 0.569) but not anaerobic performance (p = 0.135). Glucocorticoids did not change energy expenditure during submaximal performance (SDM 0.0.225 95% CI −0.771 to 0.112).Discussion: This study indicates that glucocorticoids improves maximal performance and aerobic performance. Glucocorticoids did not affect the energy expenditure during submaximal performance. The conclusions are based on relatively few subjects leading to limited statistical power and uncertain estimates. Still, these results are consistent and should be of interest to WADA and anyone concerned about fair play.Systematic Review Registration: Open Science Framework 2021-04-29 (https://osf.io/fc29t/).

The objective of the present study is to review and meta-analyze the effect of E-cycling on health outcomes. We included longitudinal experimental and cohort studies investigating the effect of E-cycling on health outcomes. The studies were identified from the seven electronic databases: Web of Science, Scopus, Medline, Embase, PsycINFO, Cinahl and SportDiscus and risk of bias was assessed with the revised Cochrane Collaboration Risk of Bias Tool (RoB2). We performed meta-analysis with random effects models on outcomes presented in more than one study. Our study includes one randomized controlled trial, five quasi experimental trials and two longitudinal cohort studies. The trials included 214 subjects of whom 77 were included in control groups, and the cohort studies included 10,222 respondents at baseline. Maximal oxygen consumption and maximal power output were assessed in four and tree trials including 78 and 57 subjects, respectively. E-cycling increased maximal oxygen consumption and maximal power output with 0.48 SMD (95%CI 0.16–0.80) and 0.62 SMD (95%CI 0.24–0.99). One trial reported a decrease in 2-h post plasma glucoses from 5.53 ± 1.18 to 5.03 ± 0.91 mmol L⁻¹ and one cohort study reported that obese respondents performed 0.21 times more trips on E-bike than respondents with normal weight. All the included studies had a high risk of bias due to flaws in randomization. However, the outcomes investigated in most studies showed that E-cycling can improve health.

This study aimed to investigate match running performance in U14 male soccer players in Norway, and the influence of position, competitive level and contextual factors on running performance. Locomotion was monitored in 64 different U14 players during 23 official matches. Matches were played at two different competitive levels: U14 elite level (n = 7) and U14 sub-elite level (n = 16). The inclusion criterion was completed match halves played in the same playing position. The variables’ influence on match running performance was assessed using mixed-effect models, pairwise comparisons with Bonferroni correction, and effect size. The results showed that the U14 players, on average, moved 7645 ± 840 m during a match, of which 1730 ± 681 m (22.6%) included high-intensity running (HIR, 13.5–18.5 km·h⁻¹) and sprinting (>18.5 km·h⁻¹). Wide midfielders (WM) and fullbacks (FB) covered the greatest sprint distance (569 ± 40 m) and, in addition to the centre midfield position (CM), also covered the greatest total distance (TD) (8014 ± 140 m) and HIR distance (1446 ± 64 m). Centre forwards (CF) performed significantly more accelerations (49.5 ± 3.8) compared other positions. TD (7952 ± 120 m vs. 7590 ± 94 m) and HIR (1432 ± 57 m vs. 1236 ± 43 m) were greater in U14 elite-level matches compared with sub-elite matches. Greater TD and sprint distances were performed in home matches, but, on the other hand, more accelerations and decelerations were performed in matches played away or in neutral locations. Significantly higher TD, HIR and sprinting distances were also found in lost or drawn matches. In conclusion, physical performance during matches is highly related to playing position, and wide positions seem to be the most physically demanding. Further, competitive level and contextual match variables are associated with players’ running performance.

National and international strategies and recommendations are intended to increase physical activity in the general population. Active transportation is included in interdisciplinary strategies to meet these recommendations. Cycling seems to be more health enhancing than walking for transportation since cycling seems to reduce the risk of cardiovascular disease and associated risk factors. Furthermore, the health benefits of cycling are proven to outrun the risk of injuries and mortality. Politicians seem to approve costly infrastructure strategies to increase the amount of cycling in the population to improve public health and shift to more sustainable travel habits. A linear relationship between cycle-friendly infrastructure and the amount of commuter cycling has been demonstrated. However, in Norway and on a global level, there is a lack of robust evaluations of actions and sensitive monitoring systems to observe possible change. Therefore, we aimed to develop the Norwegian bike traffic index and describe the national, regional, and local trends in counted cycle trips. We used a transparent methodology so that the index can be used, developed, and adapted in other countries. We included 89 stationary counters from the whole country. Counters monitored cycling from 2018 onward. The index is organized at local, regional, and national levels. Furthermore, the index is adjusted for population density at the counter level and presented as ratio of counted cycle trips, comparing 2018 to subsequent years. The index is presented as a percentage change with 95% confidence intervals. In Norway, counted cycle trips increased by 11% from 2018 (100, 100–100) to 2020 (111.0, 106.2–115.1), with large geographical differences. In Southern Norway, there was a significant increase of 23%, and in Northern Norway, there was a nonsignificant decrease by 8% from 2018 to 2020. The indices may indicate possible related effects of local to national cycling strategies and how the COVID-19 pandemic has affected Norwegian travel habits in urban areas.

Objectives: This study aims to validate a submaximal treadmill walking test for estimation of maximal oxygen consumption (VO _2max ) in individuals at high risk of or with chronic health conditions. Method: Eighteen participants (age 62 ± 16 years; VO _2max 31.2 ± 5.9 ml kg ⁻¹ min ⁻¹ ) at high risk of getting or with established chronic diseases performed two valid modified Balke treadmill walking protocols, one submaximal protocol, and one maximal protocol. Test duration, heart rate (HR), and rate of perceived exertion (RPE) were measured during both tests. VO _2max was measured during the maximal test. VO _2max was estimated from the submaximal test by multiple regression using time to RPE ≥ 17, gender, age, and body mass as independent variables. Model fit was reported as explained variance ( R ² ) and standard error of the estimate (SEE). Results: The model fit for estimation of VO _2max from time to RPE ≥ 17 at the submaximal test, body mass, age, and gender was R ² = 0.78 (SEE = 3.1 ml kg ⁻¹ min ⁻¹ , p ≤ 0.001). Including heart rate measurement did not improve the model fit. Conclusions: The submaximal walking test is feasible and valid for assessing cardiorespiratory fitness in individuals with high risk of or chronic health conditions.

Objective: To examine the effect of beta2-agonists on aerobic performance in healthy, non-asthmatic study participants. Design: Systematic review and meta-analysis. Eligibility criteria: We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials published until December 2019. Studies examining the effect of beta2-agonists on maximal physical performance lasting longer than 1 min were included in the meta-analysis. Data are presented as standardised difference in mean (SDM) with 95% CI. Results: The present meta-analysis includes 47 studies. The studies comprise 607 participants in cross-over trials, including 99 participants in three-way cross-over trials and 27 participants in a four-way cross-over trial. Seventy-three participants were included in parallel trials. Beta2-agonists did not affect aerobic performance compared with placebo (SDM 0.051, 95% CI −0.020 to 0.122). The SDM for the included studies was not heterogeneous (I ² =0%, p=0.893), and the effect was not related to type of beta2-agonist, dose, administration route, duration of treatment or performance level of participants. Beta2-agonists had no effect on time trial performance, time to exhaustion or maximal oxygen consumption (p<0.218). Conclusion/implication: The present study shows that beta2-agonists do not affect aerobic performance in non-asthmatic subjects regardless of type, dose, administration route, duration of treatment or performance level of participants. The results of the present study should be of interest to WADA and to anyone who is interested in equal opportunities in competitive sports. Systematic review registration: PROSPERO CRD42018109223.

Objectives We aimed to examine the effect of β2-agonists on anaerobic performance in healthy non-asthmatic subjects. Design Systematic review and meta-analysis. Eligibility criteria We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials, published until December 2019, examining the effect of β2-agonists on maximal physical performance lasting 1 min or shorter. Data are presented as standardised difference in mean (SDM) with 95% confidence intervals (95% CI). Results 34 studies were included in the present meta-analysis. The studies include 44 different randomised and placebo-controlled comparisons with β2-agonists comprising 323 participants in crossover trials, and 149 participants in parallel trials. In the overall analyses, β2-agonists improved anaerobic performance by 5% (SDM 0.29, 95% CI 0.16 to 0.42), but the effect was related to dose and administration route. In a stratified analysis, the SDM was 0.14 (95% CI 0.00 to 0.28) for approved β2-agonists and 0.46 (95% CI 0.24 to 0.68) for prohibited β2-agonists, respectively. Furthermore, SDM was 0.16 (95% CI 0.02 to 0.30) for inhaled administration and 0.51 (95% CI 0.25 to 0.77) for oral administration, respectively, and 0.20 (95% CI 0.07 to 0.33) for acute treatment and 0.50 (95% CI 0.20 to 0.80) for treatment for multiple weeks. Analyses stratified for the type of performance showed that strength (0.35, 95% CI 0.15 to 0.55) and sprint (0.17, 95% CI 0.06 to 0.29) performance were improved by β2-agonists. Conclusion/implication Our study shows that non-asthmatic subjects can improve sprint and strength performance by using β2-agonists. It is uncertain, however, whether World Anti-Doping Agency (WADA)-approved doses of β2-agonists improve performance. Our results support that the use of β2-agonists should be controlled and restricted to athletes with documented asthma. Systematic review registration PROSPERO CRD42018109223.