**3. Results**

#### *3.1. Participant Demographics, Sports Exposure and Training*/*Competition*/*Other Sports Practices*

Male participants were characterized as follows: age: 16.1 ± 1.1 y; weight: 65 ± 10 kg; height: 1.74 ± 0.08 m; BMI: 21.5 ± 2.3 kg/m2; years of sports participation: 8.1 ± 2.4 y. The group of female participants had the following characteristics: age: 16 ± 1 years; weight: 56.2 ± 6.4 kg; height: 1.65 ± 0.05 m; BMI: 20.7 ± 1.9 kg/m2; years of sports participation: 7.1 ± 2.9 y. Over the past competition (i.e., winter) season, the participants reported a mean of 85.4 ± 47.2 days (3.5 ± 1.3 days/week) of ski training and participated in 17.2 ± 12.0 competitions on average. Independent sample t-tests revealed no significant di fferences between the sexes. However, there were significant di fferences in the number of skiing days/season (t (186) = 2.18, *p* = 0.029) and the number of competitions in the last season (t (186) = 7.22, *p* < 0.001) between the U-16 and U-18 categories, with athletes in the U-18 category who performed more skiing days and competitions. Most participants (62.8%) declared that they practiced one or more sports other than alpine skiing, 83.5% reported that they participated in specific athletic preparation programs, and 78.3% declared that they regularly warm-up before skiing. The Chi-squared tests revealed, however, no significant sex or category di fferences in these variables at *p* < 0.05.

#### *3.2. Prevalence of Lower Back Complaints*

An overview of the NMQ-related results is presented in Table 1. A total of 80.3% of all participants reported having suffered from lower back complaints during the last 12 months, and 50.0% during the last 7 days. As many as 28.2% reported that they have been restricted in normal activities (e.g., job and leisure activities) during the last 12 months, and 27.7% indicated that their lower back complaints required medical attention during the last 12 months. Except for lower back complaints during the last 7 seven days, which were more frequent in females, there were found no sex or category differences. Interestingly, 50.7% of the participants reported their lower back complaints being attributed to performing SL, 26.0% to GS, and 7.3% to SG; meanwhile, no participants attributed their lower back complaints to DH skiing. A remarkable season period-related difference in the frequency patterns of lower back complaints was found between the competition period and the off-season period. During the off-season period, only 3.3% reported their lower back complaints to last longer than two weeks, while during the competition period this percentage proportion was more than six times higher (21.3%).

**Table 1.** Overview of the Nordic Musculoskeletal Questionnaire (NMQ)-based results and differences between sexes and categories.


All NMQ-related measures are expressed as absolute numbers and the percentage proportion on the overall group/subgroups (number of affected skiers/number of skiers per group × 100). Levels of significance for sex and category differences are based on Pearson chi-square tests. n.s.: not significant at *p* < 0.05; U-16: under 16 years; U-18: under 18 years.

#### *3.3. Severity of Lower Back Complaints*

The GCPS-related results are summarized in Table 2. The mean value of Characteristic Pain Intensity was 37.53 ± 18.0 and the Disability Score was 13.27 ± 14.59 on average. There were no significant sex or category differences at *p* < 0.05. Most participants (57.4%) suffered from low intensity—low disability complaints (Grade I), and 21.8% from high intensity—low disability complaints (Grade II). Again, there were no significant differences between males and females, or between U-16 and U-18 skiers.



GCPS scores are expressed as mean ± SD. GCPS classifications are expressed as absolute numbers and the percentage proportion of the overall group/subgroups (number of affected skiers/number of skiers per group × 100). Levels of significance for sex and category differences are based on independent sample *t*-tests and Pearson chi-square tests, respectively. n.s.: not significant at *p* < 0.05; U-16: under 16 years; U-18: under 18 years.

#### *3.4. Relationship between Di*ff*erent Severity Measures, as well as between Severity and Training Attributes*

We found a medium-correlation Characteristic Pain Intensity and Disability Score (r = 0.62, *p* < 0.01). Moreover, the average lower back complaint intensity, as well as the intensity at the time of filling out the questionnaire, positively correlated with the worst pain intensity experienced within the last 6 months (r = 0.63, *p* < 0.01; r = 0.47, *p* < 0.01, respectively).

The results of the correlation analysis between the GCPS scores and di fferent training attributes are highlighted in Table 3. There were small ye<sup>t</sup> significant correlations between the Characteristic Pain Intensity and the training attributes "years of sports participation", "number of competitions/season", and "number of skiing days/season". Moreover, an additional independent *t*-test showed a significant di fference (t (186) = 2.12, *p* = 0.035, d = 0.31) in the lower back complaint severity (i.e., GCPS—Characteristic Pain Intensity) between skiers who exclusively practiced alpine skiing and those who also practiced other sports, with the first group reporting higher intensities.


**Table 3.** Correlation between the Grading Chronic Pain Scale scores and questions on sports exposure.

> Level of significance based on Pearson correlation analysis: \* *p* < 0.05, \*\* *p* < 0.01.
