Effects of increased exercise intensity on the heart’s stroke volume in elite female cross country skiers

Purpose: Previous research has shown that endurance trained (ET) males increase stroke volume (SV) progressively with increasing exercise intensity up to maximal oxygen uptake (VO2max). However, few investigations have included ET female subjects. The purpose of this study was to investigate the SV response to increased exercise intensity in ET women. Method: Thirteen elite female cross country skiers were tested for VO2max using the Metamax II. Cardiac output (Q) was measured at rest, 40%, 60%, 80% and 100 % of VO2max, using the single breath acetylene rebreathing method. SV was calculated by dividing Q with HR. Results: Mean VO2max was 67.1 ± 6.1 ml∙kg‐1∙min‐1, 4.072 ± 0.219 L∙min‐1. Mean SVrest was 72.3 ± 12.6 mL∙beat‐1 and mean SVmax was 129.1 ± 16.3 mL∙beat‐1. The SV increased from rest to 40% of VO2max, plataued from 40‐80 % of VO2max and then increased from 80‐100% of VO2max (P<0.05). Qrest was 6.6 ± 0.6 L∙min‐1 and Qmax was 23.5 ± 2.5 L∙min‐1. Q increased progressively with increasing exercise intensity up to VO2max (P<0.05). Conclusion: The SV of the present elite female cross country skiers increased from rest to 40% of VO2max, plataued from 40‐80 % of VO2max and then made a secondary increase from 80‐100% of VO2max.The hypothesis of a progressive increase in SV with increased exercise intensity, as observed in ET men, was thus rejected

Long-term development of performance, physiological, and training characteristics in a world-class female biathlete

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The Training Characteristics of World-Class Male Long-Distance Cross-Country Skiers

Purpose: To investigate the training characteristics of world-class long-distance cross-country skiers. Methods: Twelve world-class male long-distance cross-country skiing specialists reported training from their best season, through a questionnaire and follow-up interviews. Training data were systemized by training form (endurance, strength, and speed), intensity [low- (LIT), moderate- (MIT), and high-intensity training (HIT)], and exercise mode, followed by a division into different periodization phases. Specific sessions utilized in the various periodization phases were also analyzed. Results: The annual training volume was 861 ± 90 h, consisting of 795 ± 88 h (92%) of endurance training, 53 ± 17 h (6%) of strength training, and 13 ± 14 h (2%) of speed training. A pyramidal (asymptotic) endurance training distribution was employed (i.e., 88.7% LIT, 6.4% MIT, and 4.8% HIT). Out of this, 50–60% of the endurance training was performed with double poling (DP), typically in the form of a daily 3- to 5-h session. A relatively evenly distributed week-to-week periodization of training load was commonly used in the general preparation period, whereas skiers varied between high-load training weeks and competition weeks, with half the training volume and a reduced amount of DP during the competition period. Conclusions: To match the specific demands of long-distance cross-country skiing, specialized long-distance skiers perform relatively long but few training sessions and use a pyramidal intensity distribution pattern and a large amount of training spent using the DP technique

Intensity Control During Block-Periodized High-Intensity Training : Heart Rate and Lactate Concentration During Three Annual Seasons in World-Class Cross-Country Skiers

Purpose: To describe heart rate (HR) and blood lactate (Bla−) responses during high-intensity interval training (HIT) in a long-term block-periodized HIT regimen in world-class cross-country (XC) skiers. Methods: Data were collected in 14 world-class female XC skiers (aged 25 ± 5 years; body mass, 60.4 ± 6.5 kg; and maximal HR, 194 ± 8 beats · min−1) throughout three entire seasons. The HR and Bla− values were determined at the end of 572 intervals performed during 63 sessions and 17 HIT blocks utilizing different exercise modes: running, running with poles, and skiing (on-snow and roller ski) with classic and skating techniques. Results: The mean HR was 91 ± 3% of HRmax with a corresponding Bla− of 7.3 ± 2.1 mmol · L−1. The average HR and Bla− values were relatively similar across the different exercise modes, except for a lower HR (~90 vs. 92% of HRmax) for on-snow and roller ski classical skiing and lower Bla− values (5.9 vs. 7.0–7.8 mmol · L−1) for on-snow classical skiing compared to the other modes, both P < 0.05. An increase in HR and Bla− was observed from interval working periods 1 to 3 (90–92% of HRmax and 6.5–7.7 mmol · L−1) and further from 3 to 5 (92–93% of HRmax and 7.7–9.0 mmol · L−1), all P < 0.05. Conclusions: We describe long-term use of HIT-block periodization among world-class XC skiers who achieved target HR and Bla− levels in all six exercise modes employed. According to athletes and coaches, the key to successful blocks was intensity control to allow for high-quality HIT sessions throughout the entire HIT block.publishedVersionUnit Licence Agreemen

Comparison of a Traditional Graded Exercise Protocol With a Self-Paced 1-km Test to Assess Maximal Oxygen Consumption

Purpose: To compare the assessment of the maximal oxygen consumption (VO2max) in a traditional graded exercise test (GXT) with a 1-km self-paced running test on a nonmotorized treadmill in men and women. Methods: A total of 24 sport-science students (12 women: age 23.7 [7.7] y, body height 1.68 [0.02] m, body mass 66.6 [4.3] kg; 12 men: 22.1 [3.1] y, body height 1.82 [0.06] m, body mass 75.6 [11.0] kg) performed a traditional GXT on a motorized treadmill and a 1-km self-paced running test on a nonmotorized treadmill. VO2max, blood lactate, heart rate, and rating of perceived exertion, together with running velocity and duration at each test, were measured. Results: The main findings of the study were that the 1-km test produced significantly higher VO2max values (53.2 [9.9] vs 51.8 [8.8] mL/kg/min ) and blood lactate concentrations (11.9 [1.8] vs 11.1 [2.2] mmol/L) than the GXT (F ≥ 4.8, P ≤ .04, η2 ≥ .18). However, after controlling for sex, these differences were only present in men (60.6 [8.1] vs 58.1 [8.0] mL/kg/min , P = .027). Peak running velocity was higher in the GXT than in the 1-km test (15.7 [2.7] vs 13.0 [2.8] km/h). Men had higher VO2max values and running velocities than women in both tests. However, men and women used approximately similar pacing strategies during the 1-km test. Conclusions: Higher VO2max values were observed in a 1-km self-paced test than in the GXT. This indicates that a 1-km running test performed on a nonmotorized treadmill could serve as a simple and sport-specific alternative for the assessment of VO2maxacceptedVersio

Preparing for the Nordic skiing events at the Beijing Olympics in 2022 : Evidence-based recommendations and unanswered questions

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One long vs. two short sessions? Physiological and perceptual responses to low-intensity training at self-selected speeds in cross-country skiers

Author's accepted version (postprint).This is an Accepted Manuscript of an article published by Human Kinetics in International Journal of Sports Physiology and Performance (IJSPP) on 22/8/22.Available online: doi.org/10.1123/ijspp.2022-0212acceptedVersio

Long-Term Development of Training Characteristics and Performance-Determining Factors in Elite/International and World-Class Endurance Athletes: A Scoping Review

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) point out existing knowledge gaps and provide methodological guidelines for future research in this field. Methods - This review was conducted following the Joanna Briggs Institute methodology for scoping reviews. Results - Out of 16772 screened items across a 22-year period (1990-2022), a total of 17 peer-reviewed journal articles met the inclusion criteria and were considered for further analysis. These 17 studies described athletes from seven different sports and seven different countries, with 11 (69%) of the studies being published during the last decade. Of the 109 athletes included in this scoping review, one quarter were women (27%), and three quarters were men (73%). Ten studies included information about the long-term development of training volume and training intensity distribution. A non-linear, year-to-year increase in training volume was found for most athletes, resulting in a subsequent plateau. Furthermore, 11 studies described the development of performance determining factors. Here, most of the studies showed improvements in submaximal variables (e.g., lactate/anaerobic threshold and work economy/efficiency) and maximal performance-indices (e.g., peak speed/watt during performance testing). Conversely, the development of VO2max was inconsistent across studies. No evidence was found regarding possible sex differences in development of training or performance-determining factors among endurance athletes. Conclusion - Overall, a low number of studies describing the long-term development of training and performance-determining factors is available. This suggests that existing talent development practices in endurance sports are built upon limited scientific evidence. Overall, there is an urgent need for additional long-term studies based on systematic monitoring of athletes from a young age utilizing high-precision, reproducible measurements of training and performance-determining factors

From juniors to seniors: changes in training characteristics and aerobic power in 17 world-class cross-country skiers

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 and seven female world-class XC-skiers, collectively holding 38 Olympic medals. Training was categorized by form (endurance, strength, speed, other) and mode (specific, unspecific) and was divided into low- (LIT), moderate- (MIT), and high-intensity training (HIT). Results: Total training increased by 203 ± 130 h (35% ± 31%, p < .001, large effect) and 78 ± 69 sessions (21% ± 24%, p < .001, very large effect). Junior training volume (658 ± 107 h) did not correlate with senior volume (861 ± 74 h) but correlated negatively with changes in volume (r = −.822, p < .001). No sex differences were observed related to total volume, but distance skiers increased their total volume more than sprint skiers (p = .037, large effect). Endurance training increased by 197 ± 117 h (p < .001; large effect) tied to increased low-intensity training (186 ± 115 h, p < .001; large effect) and moderate-intensity training (13 ± 7 h, p < .001; large effect). Training intensity distribution (% LIT/MIT/HIT) was 91/3/6 in junior and 92/4/4 in senior season. Women demonstrated greater increase of unspecific modes (100 ± 58 vs. 37 ± 44 h, p = .022; large effect) and strength training (25 ± 23 vs. −3 ± 17 h, p = .010, large effect). Men improved absolute (8% ± 5%; p = .009; large effect) and relative VO2max (6% ± 4%; p = .016; large effect) from junior to senior, while women only increased relative VO2max (7% ± 5%, p = .012; large effect). Conclusion: This study provides novel information regarding changes in training characteristics and aerobic power from junior to senior age in world-class XC-skiers. Overall, the enhanced training volume during this transition was primarily driven by increased LIT and MIT and the exceptionally high relative VO2max at junior age further increased in both sexes.publishedVersio

“Mission impossible”? How a successful female cross-country skier managed a dual career as a professional athlete and medical student : A case study

The aim of the present case study is to illuminate the factors contributing to the initiation, maintenance and discontinuation of the dual career of a Norwegian world-class athlete and medicine student. We additionally aimed to highlight contextual factors facilitating and impeding the dual career development. The participant Astrid Uhrenholdt Jacobsen was a Norwegian student-athlete in the 2005–2020 period when she concurrently achieved 10 FIS World Championship medals, one Olympic medal, and 43 World Cup podiums in cross-country ski- ing. Day-to-day training diary data, study load and progress, performance, and interviews were analysed. In most years, the participant’s annual training vol- ume was c. 800–900 hrs/year. No significant differences in athletic performance were seen between the years with full-time studies, part-time studies, and study breaks. The participant Jacobsen experienced conflicting schedules and a lack of dual career support from stakeholders as the major challenges. Hence, the present single-case study provides unique data on the process and management of a dual career.publishedVersio