35 research outputs found
Improving the Methodology of Training Load and Injury Risk Research: An Analysis of Analyses
No full textAvhandling (doktorgrad) - Norges idrettshøgskole, 2023Background: Sport injuries burden professional and recreational athletes. In 2021, Norwegian hospitals operated 1 462 anterior cruciate ligaments, and 62% of these happened during sports activity. To prevent injuries, it may be possible to change the training load. Unfortunately, how training load can be altered to achieve desired outcomes is unknown, because the relationship between training load and injury risk has proven difficult to study. The ability of currently used statistical methods to capture this complex relationship is either limited, or unknown. Consequently, studies have employed a plethora of statistical approaches. Systematic reviews have reported inconsistent and even conflicting findings both within and between studies, and declared the studies too variable to compare in analyses. Experts have questioned the evidence supporting training load as an injury prevention tool, and called for improved statistical methodology. Despite this, few studies have recommended alternatives, and those who have, have not tested the methods’ accuracy or precision. The validity of recommended methods is therefore unknown. To improve research on injury prevention programs, knowledge is needed on how to statistically determine the relationship of training load and injury risk.
Aims: To identify statistical methods suitable for assessing the relationship between training load and injury risk. Specifically, to find methods for dealing with 1) missing data, 2) non-linearity, 3) time-dependent effects, and 4) the effects of relative training load.
Main Methods: We analyzed three football datasets and one handball dataset: Norwegian Premier League men’s football (42 players, 38 injuries), Norwegian U-19 football (81 players, 81 injuries), Norwegian elite youth handball (205 players, 471 injuries), and Qatar Stars League (QSL) football (1 465 players, 1 977 injuries). In all Norwegian cohorts, training load was defined as the number of minutes in training/match activity multiplied by the athlete’s rating of perceived exertion on a scale from 1 to 10 (sRPE). The Norwegian Premier League data additionally had measures of distance and speed registered by Global Positioning Systems (GPS) devices in football. In the QSL cohort, training load was defined as the number of minutes in football training/activity.
The Norwegian Premier League football and Norwegian elite youth football were the basis for three simulation studies (Paper I–III). We simulated a relationship between training load and probability of injury under different scenarios of missing data, non-linearity, and time-dependent effects. With the aid of accuracy and uncertainty measures, we compared the ability of various statistical methods to model the simulated relationships in the respective scenarios.
Regression analyses were used to check whether there were any signs of non-linearity between sRPE and injury risk in the three Norwegian cohorts (Paper II), and also signs of time-dependent effects between training load and injury risk in the handball and QSL cohorts (Paper III–IV). In addition, we applied a novel approach of estimating the effect of recent training load relative to past training load on injury risk (relative training load) on the Norwegian elite U-19 and QSL data (Paper IV).
Main Results: In each of the simulations, the performance of a few methods stood out from the rest. Firstly, for handling missing data, multiple imputation using predicted mean matching had, generally, the lowest percentage bias of all compared methods, and had acceptable bias (< |5%|) up to 50% missing data in sRPE and up to 90% missing data in the total distance GPS measure. Secondly, when we modelled parabolic non-linear relationships, fractional polynomials, quadratic regression and restricted cubic splines had the lowest root-mean-squared error, and highest coverage of 95% prediction intervals. Lastly, in the simulation of time-dependent effects, the distributed lag non-linear model was the only method that accurately modelled more than one scenario. It had the lowest root-mean-squared error and the narrowest 95% confidence intervals, by far, compared with the other methods.
The handball model presented a parabolic J-shaped relationship between sRPE and injury risk (p < 0.001). The QSL model displayed time-dependent effects, where effect estimates of past training load decreased exponentially for each day in the past. The QSL model also showed highest injury risk at low levels of past training load, lowest risk at medium levels, and intermediate risk at high levels of past training load, for each level of recent training load. This demonstrated that relative training load can be modelled with this novel approach.
Conclusion: Missing data in training load should be imputed with multiple imputation using predicted mean matching. Researchers in training load and injury risk should consider the potential for non-linearity and time-dependent effects, and explore such effects by specifying fractional polynomials or restricted cubic splines in distributed lag non-linear models. Modelling recent and past training load separately can be used to study the effects of relative training load on injury risk.publishedVersionInstitutt for idrettsmedisinske fag / Department of Sports Medicin
The Evolutionary Potential of Male Plumage Color in a Hybrid Sparrow Species
No full textHybridization is increasingly recognized as a source of novel variation, but how hybridization can contribute to evolution is still not fully understood. Insights into the evolutionary potential of hybrid species, and the extent to which two parent species are constrained to form only a single specific hybrid phenotype, would increase our understanding of the impact of hybridization on evolution, adaptation and diversity. Here, I address these questions using the Italian sparrow (Passer italiae), a homoploid hybrid bird species formed from hybridization between house (P. domesticus) and Spanish sparrows (P. hispaniolensis). Using multivariate quantitative genetics methods, I examine four sexually dimorphic plumage traits (crown, back, rump and cheek) in males of all three species. For Italian sparrows, I compare three geographically separated island populations, which differ in genomic composition, to examine whether these populations vary in phenotype and whether they have more potential to evolve and diversify than the parent species. I show that the Italian sparrow is mosaic in its plumage pattern; some traits are similar to one of the parent species, others are similar to the other parent, but the Italian sparrow also has transgressive color values for back and rump (that is, outside the phenotypic range of either parent). In spite of strong parallelism in some traits, such as crown, island populations differ in some plumage traits, revealing that more than one phenotype can be formed by the same parent species. Alongside phenotypic novelty, the Italian sparrow has higher variability and evolvability than the parent species, showing that hybridization can indeed act as a source of new variation. However, my results indicate that, after initial hybridization, selection on secondary sexual signals can be strong along the axis of parental divergence in a hybrid species, as suggested by a pattern of low evolvability along this axis and fixation for one of the parental values for some traits in the Italian sparrow. This selection may be determined by inheritance patterns of parental female preferences in the hybrid species
Lower HAGOS subscale scores associated with a longer duration of groin problems in football players in the subsequent season
No full textIntroduction Groin injuries represent a considerable problem in football. Although the Adductor Strengthening Programme reduced groin injury risk, players can still experience groin symptoms throughout the season. This study aimed to determine whether preseason Copenhagen Hip and Groin Outcome Score (HAGOS) and a history of previous injury can identify individuals at risk of having a longer duration of groin problems the subsequent season, using an ‘any physical complaint’ definition of injury.Methods Preseason HAGOS score and weekly groin problems were registered with the Oslo Sports Trauma Research Center Overuse questionnaire during one full season in 632 male semiprofessional adult players.Results The prognostic model showed a decreased number of weeks with groin problems for each increase in HAGOS score for ‘groin-related quality of life’ (QOL) (IRR=0.99, p=0.003). A 10-point higher ‘QOL’ score predicted 10% fewer weeks of groin problems. Additionally, previous hip/groin injury was associated with a 74% increase in the number of weeks with symptoms (p<0.001).Conclusion The HAGOS questionnaire applied preseason can detect players at risk of getting more weeks with groin problems the following season. The ‘QOL’ subscale seems to be the superior subscale for estimating subsequent groin problem duration. While HAGOS appears promising in identifying players at risk, previous groin injury is the most robust indicator, showing a substantial 74% increase in weeks with symptoms
Association of Training and Game Loads to Injury Risk in Junior Male Elite Ice Hockey Players: A Prospective Cohort Study
No full textBackground: Training and game loads are potential risk factors of injury in junior elite ice hockey, but the association of training and game loads to injuries is unknown. Purpose: To investigate the association of chronic training and game loads to injury risk in junior male elite ice hockey players. Study Design: Cohort study; Level of evidence, 2. Methods: In this prospective cohort study, we monitored all health problems among 159 male junior ice hockey players (mean age, 16 years; range, 15-19 years) at sports-specific high schools during the 2018-2019 school year. Players reported their health problems every week using the Oslo Sports Trauma Research Center Overuse Questionnaire on Health Problems (OSTRC-H2). The number of training sessions and games was reported for 33 weeks. We calculated the previous 2-week difference in training/game loads as well as the cumulative training/game loads of the previous 2, 3, 4, and 6 weeks and explored potential associations between training/game loads and injury risk using mixed-effects logistic regression. Results: The players reported 133 acute injuries, 75 overuse injuries, and 162 illnesses in total, and an average of 8.8 (SD ±3.9) training sessions and 0.9 (SD ± 1.1) games per week. We found no association between the difference of the two previous weeks or the previous 2- 3- and 4-week cumulative, training or game load and acute injuries, nor the difference of the two previous weeks, or the previous 4- and 6-week cumulative, training or game load and overuse injuries (OR, ∼1.0; P > .05 in all models). Conclusion: In the current study of junior elite ice hockey players, there was no evidence of an association between cumulative exposure to training/game loads and injury risk
An examination of training load, match activities, and health problems in Norwegian youth elite handball players over one competitive season
No full textThis is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Talent development is integral to the policy and organizational practice of competitive sport, but has also been associated with excessive amounts of training and competition, and athlete injuries and illnesses. The lack of available prospective data on the training and match activities of youth athletes and their health problems is therefore of concern. The aim of this study was twofold: (a) to examine the amount and frequency of training load, match activities, injury and illness incidence and prevalence among Norwegian youth elite handball players over the course of the 2018-2019 competitive season; and (b) to explore whether the injury rates are related to the sex or competition level of players, or their membership of the youth international team. We recruited 205 handball players (64% female, 36% male), aged 15 to 18 years (17.2 years ± 0.9) from five different sport school programs in southeast Norway. Data were collected daily from September 2018 to May 2019, during the competitive handball season. The variables included: types of athlete activities, the number of activities, the rating of perceived exertion (RPE), and the duration of training and matches. Injury and illness data were collected weekly using the Oslo Sports Trauma Research Center (OSTRC) questionnaire. The mean number of matches per week per player was 0.9 ± 1.29; the number of weekly training events was 6.1 ± 4.4; and the mean weekly session RPE was 986 ± 1 412 arbitrary units. The players reported a total of 472 injuries, and the mean number of injuries per player was 2.3 ± 2.9. The results demonstrated a 53% weekly injury prevalence, of which 38% were categorized as substantial injuries. Male players and players who participated at the highest level of senior competition and/or the youth international team reported significantly lower weekly incidences of health problems, compared to other players. Our findings showed that players enrolled in sport school programs are exposed to high training and competition loads, and that both general and substantial health problems are common. The potential implications for talent development and future research are discussed.publishedVersionInstitutt for idrett og samfunnsvitenskap / Department of Sport and Social Science
Incidence and risk factors of intraoperative periprosthetic femoral fractures during primary total hip arthroplasty: 218,423 cases reported to the Norwegian Arthroplasty Register between 1987 and 2020
No full textBackground and purpose: Intraoperative periprosthetic femoral fractures (IPFFs) can occur during primary total hip arthroplasty (THA). We describe the incidence of IPFFs during THA in Norway and estimate potential risk factors that could be associated with IPFF
Patients and methods — Data from the Norwegian Arthoplasty Register (1987–2020) was used: 2,268 IPFFs from 218,423 primary THAs in 172,598 patients. The following factors were analyzed: sex, age, diagnosis, previous operation on the same hip, surgical approach, and stem fixation technique. Association of these factors with IPFF risk was assessed using multivariable Poisson regression.
Results: IPFF occurred during 2,268 operations with an incidence of 1.0% among all primary THAs. The risk of IPFF was associated with female sex (relative risk 1.8; 99% CI 1.5–2.1), age 80–90 years and age over 90 years (compared with age 60–70 years: 1.3; CI 1.0–1.6 and 2.6; CI 1.6–4.3, respectively), non-osteoarthritis diagnoses (2.2; CI 1.9–2.6), previous surgery to the same hip (1.8; CI 1.5–2.2), lateral approach (compared with the posterior approach: 1.5; CI 1.1–2.0), and cementless stem fixation (2.7; CI 2.0–3.6).
Interpretation: Surgeons should be aware of the factors associated with an increased risk of IPFF: female sex, age above 80 years, non-osteoarthritis diagnoses, and previous surgery to the same hip. Cemented stem fixation and posterior approach should be favored in high-risk patients, such as elderly women.publishedVersio
Not straightforward: Modelling non-linearity in training load and injury research
No full textObjectives
To determine whether the relationship between training load and injury risk is non-linear and investigate ways of handling non-linearity.
Methods
We analysed daily training load and injury data from three cohorts: Norwegian elite U-19 football (n=81, 55% male, mean age 17 years (SD 1)), Norwegian Premier League football (n=36, 100% male, mean age 26 years (SD 4)) and elite youth handball (n=205, 36% male, mean age 17 years (SD 1)). The relationship between session rating of perceived exertion (sRPE) and probability of injury was estimated with restricted cubic splines in mixed-effects logistic regression models. Simulations were carried out to compare the ability of seven methods to model non-linear relationships, using visualisations, root-mean-squared error and coverage of prediction intervals as performance metrics.
Results
No relationships were identified in the football cohorts; however, a J-shaped relationship was found between sRPE and the probability of injury on the same day for elite youth handball players (p<0.001). In the simulations, the only methods capable of non-linear modelling relationships were the quadratic model, fractional polynomials and restricted cubic splines.
Conclusion
The relationship between training load and injury risk should be assumed to be non-linear. Future research should apply appropriate methods to account for non-linearity, such as fractional polynomials or restricted cubic splines. We propose a guide for which method(s) to use in a range of different situations
An examination of training load, match activities, and health problems in Norwegian youth elite handball players over one competitive season
No full textTalent development is integral to the policy and organizational practice of competitive sport, but has also been associated with excessive amounts of training and competition, and athlete injuries and illnesses. The lack of available prospective data on the training and match activities of youth athletes and their health problems is therefore of concern. The aim of this study was twofold: (a) to examine the amount and frequency of training load, match activities, injury and illness incidence and prevalence among Norwegian youth elite handball players over the course of the 2018-2019 competitive season; and (b) to explore whether the injury rates are related to the sex or competition level of players, or their membership of the youth international team. We recruited 205 handball players (64% female, 36% male), aged 15 to 18 years (17.2 years ± 0.9) from five different sport school programs in southeast Norway. Data were collected daily from September 2018 to May 2019, during the competitive handball season. The variables included: types of athlete activities, the number of activities, the rating of perceived exertion (RPE), and the duration of training and matches. Injury and illness data were collected weekly using the Oslo Sports Trauma Research Center (OSTRC) questionnaire. The mean number of matches per week per player was 0.9 ± 1.29; the number of weekly training events was 6.1 ± 4.4; and the mean weekly session RPE was 986 ± 1 412 arbitrary units. The players reported a total of 472 injuries, and the mean number of injuries per player was 2.3 ± 2.9. The results demonstrated a 53% weekly injury prevalence, of which 38% were categorized as substantial injuries. Male players and players who participated at the highest level of senior competition and/or the youth international team reported significantly lower weekly incidences of health problems, compared to other players. Our findings showed that players enrolled in sport school programs are exposed to high training and competition loads, and that both general and substantial health problems are common. The potential implications for talent development and future research are discussed
Not straightforward: modelling non-linearity in training load and injury research
No full textObjectives: To determine whether the relationship between training load and injury risk is non-linear and investigate ways of handling non-linearity. Methods: We analysed daily training load and injury data from three cohorts: Norwegian elite U-19 football (n=81, 55% male, mean age 17 years (SD 1)), Norwegian Premier League football (n=36, 100% male, mean age 26 years (SD 4)) and elite youth handball (n=205, 36% male, mean age 17 years (SD 1)). The relationship between session rating of perceived exertion (sRPE) and probability of injury was estimated with restricted cubic splines in mixed-effects logistic regression models. Simulations were carried out to compare the ability of seven methods to model non-linear relationships, using visualisations, root-mean-squared error and coverage of prediction intervals as performance metrics. Results: No relationships were identified in the football cohorts; however, a J-shaped relationship was found between sRPE and the probability of injury on the same day for elite youth handball players (p<0.001). In the simulations, the only methods capable of non-linear modelling relationships were the quadratic model, fractional polynomials and restricted cubic splines. Conclusion: The relationship between training load and injury risk should be assumed to be non-linear. Future research should apply appropriate methods to account for non-linearity, such as fractional polynomials or restricted cubic splines. We propose a guide for which method(s) to use in a range of different situations
Causal inference did not detect any effect of jump load on knee complaints in elite men's volleyball
No full textThe aim was to determine how jump load affects knee complaints in elite men's volleyball. We collected data from four men's premier league volleyball teams through three seasons in a prospective cohort study (65 players, 102 player-seasons). Vert inertial measurement devices captured the jump load (jump frequency and jump height) from 21 088 daily player sessions, and knee complaints were reported in 3568 weekly OSTRC-O questionnaires. Mixed complementary log–log regression models described the probability of (i) experiencing symptoms if players were currently asymptomatic, (ii) worsening symptoms if players had symptoms, and (iii) recovery from knee complaints. Based on our causal assumptions, weekly jump load was modeled as the independent variable, adjusted for age (years), weight (kg), position on volleyball team, and past jump load. No certain evidence of an association was found between weekly jump load and probability of (i) knee complaints (p from 0.10 to 0.32 for three restricted cubic splines of load), (ii) worsening symptoms if the player already had symptoms (p from 0.11 to 0.97), (iii) recovery (p from 0.36 to 0.63). The probability of knee complaints was highest for above-average weekly jump load (~1.2% for an outside hitter with mean age and height) compared with low loads (~1%) and very high loads (→ ~ 0%). The association between jump load and knee complaints risk remains unclear. Small differences in risk across observed jump load levels were observed. It would likely require substantially increased sample sizes to detect this association with certaintyCausal inference did not detect any effect of jump load on knee complaints in elite men's volleyballacceptedVersionacceptedVersio
