AUTHOR=Walther Jacob , Haugen Thomas , Solli Guro Strøm , Tønnessen Espen , Sandbakk Øyvind 

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

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1288606

DOI=10.3389/fphys.2023.1288606

ISSN=1664-042X

ABSTRACT=<p><bold>Purpose:</bold> To compare training characteristics and aerobic power (VO<sub>2max</sub>) 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.</p><p><bold>Methods:</bold> Retrospective analysis was conducted on self-reported training and VO<sub>2max</sub> 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).</p><p><bold>Results:</bold> Total training increased by 203 ± 130 h (35% ± 31%, <italic>p</italic> &lt; .001, large effect) and 78 ± 69 sessions (21% ± 24%, <italic>p</italic> &lt; .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 (<italic>r</italic> = −.822, <italic>p</italic> &lt; .001). No sex differences were observed related to total volume, but distance skiers increased their total volume more than sprint skiers (<italic>p</italic> = .037, large effect). Endurance training increased by 197 ± 117 h (<italic>p</italic> &lt; .001; large effect) tied to increased low-intensity training (186 ± 115 h, <italic>p</italic> &lt; .001; large effect) and moderate-intensity training (13 ± 7 h, <italic>p</italic> &lt; .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, <italic>p</italic> = .022; large effect) and strength training (25 ± 23 vs. −3 ± 17 h, <italic>p</italic> = .010, large effect). Men improved absolute (8% ± 5%; <italic>p</italic> = .009; large effect) and relative VO<sub>2max</sub> (6% ± 4%; <italic>p</italic> = .016; large effect) from junior to senior, while women only increased relative VO<sub>2max</sub> (7% ± 5%, <italic>p</italic> = .012; large effect).</p><p><bold>Conclusion:</bold> 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 VO<sub>2max</sub> at junior age further increased in both sexes.</p>