Background and objective
The purpose of this study is to analyze the effects of short-term off-season training (competition) on body composition, physical fitness, and isokinetic muscle functions of XC skiers.
Material and Methods
Seven XC skiers, including two national team members and five reserve national team members, participated in the study. Short-term off-season XC ski training was conducted for over 4 weeks (August–September). The physical composition, basic physical fitness, and isokinetic muscle function tests were conducted at S hospital in Seoul, South Korea before and after off-season ski training. The training program was conducted in New Zealand at S cross-country ski stadium (altitude 1350 m) in afternoons, and the ground training was conducted at Y area (altitude 300 m) in afternoons. The main training directions were polarized training and core stability. Weight training was not available because of local conditions.
Results
The short-term off-season XC ski training showed no differences (p>0.05) in body composition, such as weight, muscle mass, and body fat. There were significant differences (p<0.001) in the chest size and brachial muscle but no significant differences (p>0.05) in the antebrachial, femoral, and crural muscles. Basic physical fitness tests showed no significant differences (p>0.05) in strength, flexibility, agility, and
balance. However, the power ratio between the right and left grip strength showed significant difference (p<0.05). Peak torque of isokinetic muscle function of knee joints was measured at 60°/s.There were no significant differences (p>0.05) in both knee extensions before and after training, but, in contrast, there were significant differences (right knee, p<0.01 and left knee, p<0.05) in flexions. The ratio of the right knee flexion and extension muscle was significantly different between before and after training measurements (p<0.05). The ratio of the left and right knee flexion and extension muscle was significantly different (p<0.05) between before and after training measurements. While comparing the right and left knees, the
ratio of the knee extension and flexion was not significantly different (p>0.05) between before and after training measurements.

Conclusion
Short-term off-season XC ski training (competition) of 4 weeks increased XC skiers’ cross-section area of the chest and brachial muscle. It also improved the isokinetic muscle function of knee joints and the power of lower body. Our research is expected to provide basic information for XC skiers who plan ski training and competition during summer training period. However, further studies on the differences between roller- skating and ski training conducted during summers are needed.