AUTHOR=Johansen Jan-Michael , Sunde Arnstein , Helgerud Jan , Gjerløw Lars Erik , Støren Øyvind 

TITLE=Effects of Individual Changes in Training Distribution on Maximal Aerobic Capacity in Well-Trained Cross-Country Skiers: A Follow-Up Study

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.675273

DOI=10.3389/fphys.2021.675273

ISSN=1664-042X

ABSTRACT=<p>The purpose of this study was to evaluate individual changes in training distribution and the subsequent effects on maximal oxygen uptake (VO<sub>2max</sub>). The participants were well-trained cross-country skiers who had performed a year with no substantial changes in training prior to this study. Six cross-country skiers, who were participants in a larger previous study, volunteered for a follow-up study. All skiers performed self-motivated changes in training distribution for a new preparation period in this follow-up, generally by more high-intensity training (HIT). All training characteristics were registered from training diaries. During the follow-up period, all skiers performed an incremental VO<sub>2max</sub> test in February 2020 and August 2020. Training were categorized into three different training periods; (1) February 2019 to February 2020 (<italic>P</italic><sub>1</sub>) representing the training performed prior to the follow-up, (2) February 2020 to July 2020 (<italic>P</italic><sub>2</sub>), and (3) July 2020 to August 2020 (<italic>P</italic><sub>3</sub>). On average, the skiers increased their VO<sub>2max</sub> by 5.8 ± 5.0% (range: −1.8 to + 10.2%) during the follow-up study compared with the average VO<sub>2max</sub> during the preceding year. Total training volume increased on average by 10.0 and 25.7% in <italic>P</italic><sub>2</sub> and <italic>P</italic><sub>3</sub>, respectively, compared with <italic>P</italic><sub>1</sub>. The average volume of HIT was similar between <italic>P</italic><sub>1</sub> and <italic>P</italic><sub>2</sub> but increased 62.8% in <italic>P</italic><sub>3</sub>. However, large individual differences in training changes were observed. In conclusion, the present study revealed that individual changes in training distribution generated an increased VO<sub>2max</sub> in four out of six already well-trained cross-country skiers. Reduced total training volume (three out of six) and increased (four out of six) HIT volume were the most marked changes.</p>