Monitoring Acclimatization and Training Responses Over 17-21 Days at 1,800 m in Elite Cross-Country Skiers and Biathletes

Abstract

Objective: To monitor the daily variations and time course of changes in selected variables during a 17-21-day altitude training camp at 1,800 m in a group of elite cross-country skiers (9 women, 12 men) and biathletes (7 women, 4 men).

Methods: Among other variables, resting peripheral oxygen saturation (SpO_2rest), resting heart rate (HR_rest) and urine specific gravity (USG) were monitored daily at altitude, while illness symptoms were monitored weekly. Before and after the camp, body composition (i.e., lean and fat mass) and body mass were assessed in all athletes, while roller-skiing speed at a blood lactate concentration of 4 mmol·L^-1 (Speed_@4mmol) was assessed in the biathletes only.

Results: Neither SpO_2rest, HR_rest nor USG changed systematically during the camp (p > 0.05), although some daily time points differed from day one for the latter two variables (p < 0.05). In addition, body composition and body mass were unchanged from before to after the camp (p > 0.05). Eleven out of 15 illness episodes were reported within 4 days of the outbound or homebound flight. The five biathletes who remained free of illness increased their Speed_@4mmol by ~ 4% from before to after the camp (p = 0.031).

Conclusions: The present results show that measures typically recommended to monitor acclimatization and responses to altitude in athletes (e.g., SpO_2rest and HR_rest) did not change systematically over time. Further research is needed to explore the utility of these and other measures in elite endurance athletes at altitudes typical of competition environments.

Keywords: Nordic skiing; altitude; athlete monitoring; endurance sports; hypoxia; winter sports.

Figure 1

Schematic overview of measures during the altitude training camp. All, all athletes; XC_female, female cross-country skiers; XC_male, male cross-country skiers; BIA, biathletes; SpO₂, peripheral oxygen saturation. Shaded area indicates biathletes only.

Figure 2

Daily training load (mean ± SD) for female cross-country skiers (XC_female); male cross-country skiers (XC_male); biathletes (BIA); and all athletes (All, mean only) during the training camp. Shaded area indicates biathletes only.

Figure 3

Daily (mean ± SD) (A) resting peripheral oxygen saturation (SpO_2rest); (B) resting heart rate (HR_rest); (C) body mass; (D) urine specific gravity (USG); (E) urine color (UC); (F) overall recovery; (G) overall stress; and (H) blood urea nitrogen concentration ([U], biathletes only) during the training camp. Full circles, all participants; red circles, women; blue circles, men. Shaded areas indicate biathletes only. *Significant effect of time modeled as a discrete variable (i.e., in relation to day 1 of the camp; p < 0.05).

Figure 4

Mean ± SD (A) arterial oxygen saturation (SpO_2work); (B) relative heart rate (HR_work); (C) blood lactate concentration [La⁻]_work; and median ± IQR (D) rating of perceived exertion (RPE_work) during the 5-min submaximal cycling test at baseline (i.e., near sea level) and on three weekly occasions during the training camp (i.e., at 1,800 m). Red circles, women; blue circles, men. *Significantly different from baseline (p < 0.05).

Figure 5

Mean ± SD (A) lean mass; (B) fat mass; and (C) total body mass before and after the training camp. Red lines, women; blue lines, men.