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Magnus Carlsson, Tomas Carlsson, Daniel Hammarström, Christer Malm and Michail Tonkonogi

Purpose:

To investigate the relationship between race performance and lean mass (LM) variables, as well as to examine sex differences in body composition in elite-standard cross-country skiers.

Methods:

Thirty-four elite cross-country skiers (18 men and 16 women) underwent a dual-emission X-ray-absorptiometry body-composition test to determine LM, fat mass, and bone mineral content. For both sexes, performance data were collected from a sprint prologue and a distance race.

Results:

The absolute expression of LM variables (whole-body [LMWB], upper body [LMUB], and lower body [LMLB]) was significantly correlated with finishing time in the sprint prologue independent of sex. Distance-race performance was significantly related to LMWB, LMUB, and LMLB in women; however, no correlation was found in men. Men had a significantly higher LM and lower fat mass, independent of expression (absolute or relative), for the whole body, arms, trunk, and legs, except for the absolute fat mass in the trunk.

Conclusions:

The absolute expressions of LMWB, LMUB, and LMLB were significant predictors of sprint-prologue performance in both sexes, as well as of distance-race performance in women only. Compared with women, male skiers have a higher LM in the body segments that are major contributors to propelling forces. These results suggest that muscle mass in the lower and upper body is equally important for race performance; thus, more focus of elite skiers’ training should be directed to increasing whole-body muscle mass to improve their competitive performance capability.

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Magnus Carlsson, Tomas Carlsson, Daniel Hammarström, Christer Malm and Michail Tonkonogi

Purpose:

This study investigated whether there is a correlation between time-trial performance and competitive performance capacity of male and female junior cross-country skiers and sought to explain sex-specific competitive performance capacity through multiple-regression modeling.

Methods:

The International Ski Federation’s (FIS) junior ranking points for distance (FISdist) and sprint (FISsprint) competitions were used as performance parameters. A total of 38 elite junior (age 18.5 ± 1.0 y) cross-country skiers (24 men and 14 women) completed 3 time-trial tests: a 3-km level-running time trial (TTRun), a 2-km moderate uphill (1.2° slope) roller-skiing time trial using the double-poling technique (TTDP), and a 2-km uphill (2.8° slope) roller-skiing time trial using the diagonal-stride technique (TTDiag). The correlations were investigated using Pearson correlation analysis, and regression models were created using multiple-linear-regression analysis.

Results:

For men, FISsprint and FISdist were correlated with the times for TTRun, TTDP, and TTDiag (all P < .001). For women, FISsprint was correlated with the times for TTRun (P < .05), TTDP (P < .01), and TTDiag (P < .01), whereas FISdist was correlated only with the times for TTDP (P < .01) and TTDiag (P < .05). The models developed for FISdist and FISsprint explained 73.9–82.3% of the variance in the performance capacity of male junior cross-country skiers. No statistically valid regression model was found for the women.

Conclusions:

Running and roller-skiing time trials are useful tests for accurately predicting the performance capacity of junior cross-country skiers.

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Michael Svensson, Christer Malm, Michail Tonkonogi, Bjǒrn Ekblom, Bertil Sjödin and Kent Sahlin

The aim of the present study was to investigate the concentration of ubiquinone-10 (Q10), at rest, in human skeletal muscle and blood plasma before and after a period of high-intensity training with or without Q10 supplementation. Another aim was to explore whether adenine nucleotide catabolism, lipid peroxidation, and mitochondrial function were affected by Q10 treatment. Seventeen young healthy men were assigned to either a control (placebo) or a Q10-supplementation (120 mg/day) group. Q10 supplementation resulted in a significantly higher plasma Q10/lotal cholesterol level on Days 11 and20compared with Day 1. There was no significant change in the concentration of Q10 in skeletal muscle or in isolated skeletal muscle mitochondria in either group. Plasma hypoxanthine and uric acid concentrations increased markedly after each exercise test session in both groups. After the training period, the postexercise increase in plasma hypoxanthine was markedly reduced in both groups, but the response was partially reversed after the recovery period. It was concluded that Q10 supplementation increases the concentration of Q1O in plasma but not in skeletal muscle.