Oyvind Sandbakk

UiT The Artic University of Norway · School of Sport Science

Background Most sex comparisons in endurance sports have been derived from performance-matched groups of female and male athletes competing over similar distances within summer sports. Corresponding analyses of sex differences in winter endurance sports have not previously been conducted. In the Olympic Winter Games (OWG), the endurance sports incl...

Research on world-class athletes in endurance events, such as cycling Grand Tours, has reported extreme levels of total energy expenditure. However, it has been argued that over extended periods, such as months, sustained energy expenditure is capped at approximately 2.5 times the basal metabolic rate. Triathlon is particularly notable for its high...

Purpose : To investigate the influence of menstrual-cycle (MC) phase on objective sleep and perceived recovery following high- (HIT) and low-intensity training (LIT) in endurance-trained women. Methods : Fifteen naturally menstruating, endurance-trained women completed standardized HIT and LIT sessions during the early follicular phase (EFP), ovula...

Purpose: To describe warning signs, monitoring tools, as well as training and non-training related actions taken by world-class endurance coaches in cases of underperformance. Methods: Twelve highly acclaimed male Norwegian coaches, known for coaching world-class endurance athletes with a remarkable collection of over 350 Olympic, World, and Europe...

Background Perceived stress from schoolwork and perceived teacher care are shown to influence adolescents’ life satisfaction. However, there is a need to further explore how levels of perceived school stress affect life satisfaction of Norwegian adolescents across gender and school levels using nationwide data, and whether this association is moder...

Purpose To investigate the effect of exercise intensity on standing shooting performance and related technical variables in elite biathletes performing roller skiing and live shooting outdoors. Methods Nineteen male biathletes performed two 5-shot series in the following order of exercise intensity: rest, low (%heart rate max 73 ± 4; blood lactate...

In recent years, many countries have significantly increased military spending, mainly due to geopolitical instability in several regions and the potential risk of armed conflicts spreading worldwide. In this context, understanding the nutritional needs of soldiers in different climates (warm, cold and high altitude) is important and directly impac...

Background and Purpose : Cross-country skiing, biathlon, and Nordic combined are Winter Olympics sports that involve cross-country skiing in undulating terrain, characterized by various subtechniques and repeated intensity fluctuations. The stochastic interval profile of these sports necessitates the continuous regulation of work and energy expendi...

Purpose : To compare designs of training sessions applied by world-class cross-country skiers during their most successful junior and senior season. Methods : Retrospective analysis of self-reported training characteristics (ie, training form, intensity, and exercise mode) among 8 male and 7 female world-class cross-country skiers was conducted. Re...

Background A robust association between physical activity (PA) and satisfaction with life (SWL) has been established, wherein self-efficacy has been identified as a mediator across different populations. However, there is a need to further examine the relationship between PA and SWL and whether self-efficacy act a as mediator within different level...

Purpose To compare acute physiological responses and perceived training stress between one long and two short time- and intensity-matched sessions of moderate-intensity training in endurance athletes. Methods Fourteen male endurance athletes (VO2max: 69.2 ± 4.2 mL·min⁻¹·kg⁻¹) performed one 6 × 10-min interval session (SINGLE) and two 3 × 10-min in...

Purpose : To describe how high-level European sprint coaches (from 100 to 400 m) work to improve important factors associated with the quality of the holistic training process and the quality of the specific training session. Methods : A descriptive analysis was conducted using questionnaires from 31 European elite sprint coaches (ie, training athl...

Recent methodological recommendations suggest the use of the “3-step method,” consisting of calendar-based counting, urinary ovulation testing, and serum blood sampling, for the identification of subtle menstrual disturbances (SMDs). However, the use of the 3-step method is not always feasible, so a less demanding combination of calendar-based coun...

Background: In the last decade, a growing body of research has focused on the many aspects and challenges of combining parenthood with elite sport. Although the number of father-athletes is significantly higher than the number of mother-athletes, few studies to date have focused on male athletes’ experiences in a parenting context. Aim: The aims o...

Background Our scientific understanding of the mechanistic and practical connections between training session prescriptions, their execution by athletes, and adaptations over time in elite endurance sports remains limited. These connections are fundamental to the art and science of coaching. Objective By using successful Norwegian endurance coache...

At the 2026 winter Olympics in Milano Cortina, the biathlon events will be held in Anterselva (Antholz Biathlon Arena) at an altitude of ~1600 meter above sea level. Based on available research literature and “best-practice” approaches, the current article provides the following recommendations for altitude preparations in connection with the Olymp...

INTRODUCTION: Acute bouts of exercise can affect the functional organization of the brain and the neural processes contributing to sports performance. Exercise duration and intensity are accepted as key factors in this interplay through their association with metabolic processes which modulate neural activity [1]. Further, qualitative characteristi...

Introduction: Endurance athletes are susceptible to an imbalance between training load and recovery, which can result in maladaptation, an unexplained decrement in performance and potential overtraining syndrome. In order to prevent athletes from transitioning along the continuum from being acutely fatigued towards overtraining syndrome, early dete...

Purpose: To investigate the training and development process of a multiple Grand Slam finalist. Methods: A mixed-methods case study design was used to capture the quantitative and qualitative aspects related to the training and successful development process. We used a three-step data collection process and pragmatic analyses of (1) training histor...

Purpose : This study investigated sex differences in self-reported causes, symptoms, and recovery strategies associated with underperformance in endurance athletes. Methods : A total of 82 athletes (40 women) meeting the inclusion criteria (performance level ≥tier 3, used training diaries, and experienced 1 or more periods of underperformance durin...

Background The crucial role of physical activity (PA) in promoting well-being and overall health of adolescents is widely acknowledged. Previous global studies have consistently revealed low adherence to PA recommendations among adolescents, emphasizing potential links between PA engagement and self-efficacy in school-based populations. However, th...

In 2023, for the first time in history, the international ski and snowboard federation (FIS) arranged an official ski flying competition where the 15 highest ranked women were allowed to participate. This study investigated jump-to-jump performance development in female ski flying, with men’s results used as reference data. Official FIS data from a...

Purpose: To describe warning signs, monitoring tools, as well as training and non-training related actions taken by world-class endurance coaches in cases of underperformance. Methods: Twelve highly acclaimed male Norwegian coaches, known for coaching world-class endurance athletes with a remarkable collection of over 350 Olympic, World, and Europe...

The aim of this study was to investigate relationships between changes in training practices and human development index (HDI) levels, and identify strategies employed by athletes who consistently maintained their training quantity during the first 100 days of the COVID-19 pandemic. A total of 10,074 athletes (5290 amateur and 4787 professional ath...

Female athletes frequently perceive performance changes throughout the menstrual cycle (MC). However, if and how the MC influences performance-determining variables remains unclear. Purpose To investigate the effect of the MC and endogenous sex hormone concentrations on performance-determining variables in three distinct MC phases in endurance-tra...

A total of nineteen elite youth cross-country skiers (16 ± 2 years) were divided into three groups: a low-load group (LL, n = 6) performing 15–20 repetitions per exercise, a high-load group (HL, n = 9) executing 6–12 repetitions, and a control group (CON, n = 4) exclusively engaging in endurance training. Testing included 1RM in upper-body exercise...

The International Olympic Committee (IOC) recently published a framework on fairness, inclusion, and nondiscrimination on the basis of gender identity and sex variations. Although we appreciate the IOC's recognition of the role of sports science and medicine in policy development, we disagree with the assertion that the IOC framework is consistent...

This study aimed to investigate the variables determining performance in a simulated on-snow Skimo sprint competition, and how their relationship with performance evolves from the individual time trial to the final. Fifteen national-level junior Skimo athletes (mean ± SD: age, 17.8 ± 2.5 years; maximal oxygen uptake, 66.8 mL·kg −1 ·min −1) underwen...

Research in sport science has historically been performed in controlled laboratory conditions, as the analytical tools available were not portable or not adapted to field conditions. With the recent development in technologies and tools, a new field of research performed in more ecologically valid situations is emerging. This allows new insights to...

Purpose Advanced insight in energy requirements of Paralympic athletes is imperative for optimizing their nutritional counseling. Given the lack of accurate data on total daily energy expenditure (TDEE) of Paralympic athletes, this study aimed to assess energy expenditure and nutritional intake of a large cohort of Paralympic athletes, across diffe...

The rise of artificial intelligence (AI) applications in healthcare provides new possibilities for personalized health management. AI-based fitness applications are becoming more common, facilitating the opportunity for individualised exercise prescription. However, the use of AI carries the risk of inadequate expert supervision, and the efficacy a...

Recently, we published self-reported data concerning the perceived effects of the menstrual cycle and hormonal contraceptives on the training and performance of 1086 female athletes participating in 57 sports. However, studies comparing differences between sports with large sample sizes are lacking. The aim of this ancillary study was to compare th...

Purpose: To compare training characteristics and aerobic power (VO2max) between the most successful junior and senior seasons of world-class cross-country (XC) skiers and to identify differences between sexes and among sprint and distance skiers. Methods: Retrospective analysis was conducted on self-reported training and VO2max tests of ten male an...

Scientific knowledge of the training of elite athletic sprinters is limited, and much of their training relies on the intuition and expertise of experienced coaches. Therefore, the objective of this study is to provide an overview of the training practices employed by elite Spanish sprint coaches. A descriptive analysis was conducted using customis...

Purpose : To investigate performance-determining variables of an on-snow sprint cross-country skiing competition and the evolvement in their relationship with performance as the competition progresses from the individual time trial (TT) to the final. Methods : Sixteen national-level male junior skiers (mean [SD] age, 18.6 [0.8] y; peak oxygen uptak...

Purpose : One hundred years ago, Hill and Lupton introduced the concept of maximal oxygen uptake ( ), which is regarded as “the principal progenitor of sports physiology.” We provide a succinct overview of the evolvement of research on , from Hill and Lupton‘s initial findings to current debates on limiting factors for and the associated role of co...

The article commences with a fundamental objective: to comprehend movement skills in sports in a manner that can bridge the dualist gap between experiential qualities observed in practice and theoretical and mechanistic explanations. Drawing inspiration from Kuhn’s concept of scientific paradigms, practical examples from skiing research, and innova...

Introduction This study (i) examined Norwegian and Swedish sports coaches' employment, practices, and beliefs during the first wave of the COVID-19 pandemic, (ii) compared these aspects between coaches in Norway and Sweden, two countries with clearly different movement restrictions strategies in this period. Methods An online survey was distribute...

Purpose : To describe and compare the annual physical training characteristics between Norwegian female cross-country (XC) skiers and biathletes across competition levels and age categories. Methods : Daily training sessions for 1 year were recorded for 45 XC skiers and 26 biathletes, comprising international/national team (inter[national]) and non...

Purpose To investigate performance, physiological, and perceptual responses of an entire sprint cross-country skiing competition in the skating style. Methods Eighteen national-level male junior skiers participated in a simulated competition comprising an individual time trial (TT), followed by three heats (quarterfinals [QF], semifinals [SF], and...

Purpose: In sprint biathlon, a J-shaped pacing pattern is commonly used. We investigated whether biathletes with a fast-start pacing pattern increase time-trial skiing and shooting performance by pacing more evenly. Methods: Thirty-eight highly trained biathletes (∼21 y, 27 men) performed an individual 7.5 (3 × 2.5 km for women) or 10-km (3 × 3....

Purpose: To investigate the influence of menstrual-cycle (MC) phase on measures of recovery status, that is, resting heart rate, perceived sleep quality, and physical and mental readiness to train, among female endurance athletes. Methods: Daily data were recorded during 1 to 4 MCs (ie, duration ≥21 and ≤35 d, ovulatory, luteal phase ≥10 d) of 4...

In cross-country skiing, velocities range from 2 m $${\textrm{s}}^{-1}$$ s - 1 up to more than 20 m $${\textrm{s}}^{-1}$$ s - 1 across undulating terrain, and aerodynamics can, therefore, make a large impact on performance. The aim of this study was to investigate the influence of skiing velocity on air drag for skating sub-techniques and downhill...

Background: Elite sport is continuously evolving. World records keep falling and athletes from a longer list of countries are involved. Purpose: This commentary was designed to provide insights into present and future trends associated with world-class endurance training based on the perspectives, experience, and knowledge of an expert panel of...

The purpose of this study was to examine the influence of tactical positioning on performance in the heats of sprint cross-country (XC) skiing among men and women and the consistency of overtaking events over repeated competitions on the same racecourse. Thirty male and thirty female elite to world-class level skiers within each competition [(sprin...

Objective In this scoping review, we aimed to 1) identify and evaluate existing research that describes the long-term development of training characteristics and performance-determining factors in male and female endurance athletes reaching an elite/international (Tier 4) or world-class level (Tier 5), 2) summarize the available evidence and 3) poi...

The aim of this study was to test and adapt a treadmill-developed method for determination of inner-cycle parameters and sub-technique in cross-country roller ski skating for a field application. The method is based on detecting initial and final ground contact of poles and skis during cyclic movements. Eleven athletes skied 4 laps of 2.5 km at low...

Aims: Cardiovascular structures adapt to meet metabolic demands, but current methodology for indexing by body size does not accurately reflect such variations. Therefore, we aimed to investigate how left ventricular end-diastolic volume (LVEDV) and left atrial maximal volume (LAVmax) are associated with absolute (L/min) peak oxygen uptake (VO2peak...

When successful athletes are asked to explain the reasons behind their success, they often highlight the quality of their training. This aspect has so far received limited attention in sport science, and several fundamental questions related to this feature need to be addressed. What is training quality? What factors affect training quality? Who ma...

Introduction Although five of six Olympic events in cross-country skiing involve mass-starts, those events are sparsely examined scientifically. Therefore, in this study, we investigated speed profiles, pacing strategies, group dynamics and their performance-determining impact in a cross-country skiing mass-start competition. Methods Continuous sp...

Purpose: To determine the main factors associated with unexpected underperformance and prospectively describe the holistic process of returning to sustainable world-class level in a male cross-country skier. Methods: Longitudinal training data was retrospectively analyzed across nine seasons (2012-2013 to 2020-2021), and categorized into training f...

Purpose Acute bouts of exercise influence the communication and organization of brain networks, with exercise intensity and volume regarded as key moderators. However, differences in coordination demands and limb involvement between exercise modes may also affect the communication and organization of brain networks after exercise and should be con...

The purpose of this study was to examine the influence of race tactics for performance in the heats of an international sprint cross-country (XC) skiing competition in the classical style. Thirty elite male XC skiers (age: 24±3 years, sprint International Ski Federation [FIS] points: 61±27) performed a sprint time-trial (STT) followed by one to thr...

Objective: The aim of this study was to provide a new machine learning method to determine temporal events and inner-cycle parameters (e.g., cycle, pole and ski contact and swing time) in cross-country roller-ski skating on the field, using a single inertial measurement unit (IMU). Methods: The developed method is based on long short-term memory...

The aim of this study was to adapt a treadmill-developed method for determination of inner-cycle parameters in cross-country roller ski skating for a field application. The method is based on detecting initial and final ground-contact of poles and skis during cyclic movements. Eleven athletes skied four laps of 2.5 km at low and high endurance-inte...

Purpose: To describe menstrual cycle (MC)-related practices, knowledge, communication, and health in Indian endurance athletes and to investigate the changes in their perception of sleep quality, readiness to train, training quality, fitness, and performance across the MC. Methods: Data on female Indian athletes (N = 96, age 22 [3] y) competing...

This scientific short report investigated how successful male coaches perceive gender differences in training characteristics and coaching practice among medal-winning endurance athletes. Ten male Norwegian coaches with a track record of coaching both female and male endurance world-class athletes (total of 269 Olympic, World and European Champions...

Ramadan intermittent fasting during the COVID-19 lockdown (RIFL) may present unique demands. We investigated training practices (i.e., training load and training times) of athletes, using pre-defined survey criteria/questions, during the ‘first’ COVID-19 lockdown, comparing RIFL to lockdown-alone (LD) in Muslim athletes. Specifically, a within-subj...

Purpose: To investigate the performance effects of video- and sensor-based feedback for implementing a terrain-specific micropacing strategy in cross-country (XC) skiing. Methods: Following a simulated 10-km skating time trial (Race1) on snow, 26 national-level male XC skiers were randomly allocated into an intervention (n = 14) or control group...

Aim The purpose of this study was to examine the influence of race tactics on performance in the heats of an international sprint crosscountry (XC) skiing competition in the classical style. Methods Thirty elite male XC skiers (age: 24±3 years, sprint [FIS] points: 61±27) performed a sprint time-trial (STT) followed by one to three heats on a 1.7 k...

Purpose: To investigate differences in athletes' knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification. Methods: Athletes (12,526; 66% male; 142 countries) completed an online survey (May-July 2020...

Objective: The aim of this study was to provide a new machine learning method to determine temporal events and inner-cycle parameters (e.g., cycle, poles and skis contact and swing time) in cross-country roller ski skating on the field, using a single deported inertial measurement unit (IMU). Methods: The developed method is based on long short-ter...