This study aimed to determine the appropriate nutritional intakes and dietary habits of high school-aged cross-country skiers and speed skaters. The subjects, all high school students from N Prefecture, included 18 ma...This study aimed to determine the appropriate nutritional intakes and dietary habits of high school-aged cross-country skiers and speed skaters. The subjects, all high school students from N Prefecture, included 18 male cross-country skiers, 5 male speed skaters, 10 female cross-country ski players and 4 female speed skaters. Physical measurements, food intake frequency survey results, bone mineral density and exercise stress test outcomes, and lactic acid measurements were evaluated. Female athletes in both sports had higher body fat percentages relative to the average range stated for female athletes. Male speed skaters had a significantly higher maximum oxygen in-take than that male cross-country skiers did. By contrast, this parameter did not differ significantly among female athletes. A negative correlation was observed between the fat free mass and muscle mass, and a positive correlation was observed among the body fat percentage, fat percentage, and fat mass. Both male and female athletes had protein intake ratios within the reference ranges. All athletes except male speed skaters had lipid energy ratios that were higher than the upper limit of the reference value. Both male and female athletes also reported carbohydrate energy ratios within the reference ranges, but had cereal energy ratios below the reference values. Athletes should pay attention to the ingestion of various nutrients to ensure a sufficient energy intake. Accordingly, adolescent athletes should consume daily meals containing a good balance of staple foods, main dishes, side dishes, milk and other dairy products, and fruits.展开更多
The purpose of this study was to investigate whether eight weeks of aerobic high-intensity interval training with roller ski is effective in cross-country skiers. 10 male （age, 18.28 ± 2.1 years; height, 171.26 ...The purpose of this study was to investigate whether eight weeks of aerobic high-intensity interval training with roller ski is effective in cross-country skiers. 10 male （age, 18.28 ± 2.1 years; height, 171.26 ± 4.12 cm; weight 61.39 ± 6.28 kg） and 8 female （age, 16.05 ± 0.3 years; height, 158.3 ± 6.47 cm; weight, 49.34 ± 0.7 kg） junior cross country skiers completed the study. All skiers performed a 2 × 2-kin all-out uphill intervals with roller-skis, 3 times a week, in addition to their traditional training program. Measurements included VO2max （maximal oxygen uptake）, anaerobic power, and also for 2-km roller ski. All values were listed as pre-to post-test mean （± SD）, significant level, and percentage changes （%）. Pre-to post-testing changes in VO2max, anaerobic power, and also 2-kin roller ski performance were significantly higher during all post-test trials in all groups （P 〈 0.005）. With reference to the training effects found in our study, we suggest that the skiers should integrate the roller ski aerobic high-intensity interval uphill models in their training programs for improving performance.展开更多
The Tour de Ski(TDS:6-9 sprint and distance races across 9-11 days)represents the most intense competition series of the cross-country(XC)ski season and is characterized by accumulated stress from consecutive days of ...The Tour de Ski(TDS:6-9 sprint and distance races across 9-11 days)represents the most intense competition series of the cross-country(XC)ski season and is characterized by accumulated stress from consecutive days of high-intensity(~85%-160% VO_(2max))racing,travel,cold temperatures and low to moderate altitude(500-1500 m above sea level).Here,nutritional strategies play a key supportive role for optimized health,recovery and performance.This narrative review aims to provide an evidence-based discussion on the energetic demands of the TDS and recommendations for nutritional strate-gies to optimize health and performance of XC skiers during and following the TDS.We highlight several challenges that may arise during the TDS,including the following:poor energy availability(EA)due to decreased appetite or a pressure to maintain a low body weight,suboptimal carbohydrate availability due to a failure to replenish muscle glycogen stores across consecutive-day racing and increased risk of illness due to a combination of factors,including high-intensity racing,poor nutrition,sleep,travel and hygiene.We encourage XC skiers to maintain optimal overall EA across the~1.5-week period,ensure high daily carbohydrate availability,as well as the use of strategies to maintain a healthy immune system.In addition,we include practical guidelines on the management of nutrition support prior to and during the TDS.We recognize that many nutritional questions remain unanswered both in the context of elite XC ski racing and specifically for extreme demands like the TDS that should be addressed in future investigations.展开更多
This paper reports the effects of two trainings-5 km cross-country race and 15 min heat-bath on theimprovement of heat-tolerance. All subjects of the training group were asked to perform a training once daily for 10to...This paper reports the effects of two trainings-5 km cross-country race and 15 min heat-bath on theimprovement of heat-tolerance. All subjects of the training group were asked to perform a training once daily for 10to 12 d within two weeks. The results proved that the cross-country race training both in the artificial hot chamberand on the drill ground of troop could obtain evident training-adaptation. The rectal temperature, heart rate, andsweat volume reduced by 0. 39℃, 13. 2 b/min and 338 g during training in field, respectively. In the same period ofcross-country race training, the normal military exercises, labours and natural heat acclimatization in the summercould only raise slightly the level of heat acclimatization in soldiers. Heat-bath training could reduce rectal temperature by 0. 6℃ during immersion in hot water, however, the level of heat-tolerance in a hot climatic chamber was inferior to that attained by cross-country race, march and running training.展开更多
in order to improve the acquired level of heat acclimatization (HA) by training, on the basis of singlemode march training (SMT) or single-mode cross-country race training (SCT) , combined training method of march and...in order to improve the acquired level of heat acclimatization (HA) by training, on the basis of singlemode march training (SMT) or single-mode cross-country race training (SCT) , combined training method of march and cross-country race in the heat was adopted in this experiment ,and the effect of the training on heat tolerance was analyzed. Eight young males were asked to perform a simulated SMT and SCT for 90 min on a treadmill in a hot climate chamber (Td 32. 7℃ , WBGT 28. 4℃ ) once daily for 10 to 12 d within two weeks. The results showed that rectal temperature (Tr) was reduced by 0. 61℃ , heart rate (Hr) by 8. 5 b/min,sweat volume (SV)by 0. 220 kg, physiological strain index (PSI)by 0. 620,systolic pressure (SP)and diastolic pressure (DP) had a little change, pulse pressure (PP) and stroke volume (StV) increased , and cardiac output (CO) decreased a little at the middle stage and increased at the late stage due to Hr change. The standardized bicycle ergometer test (SBE test) in the heat (Td 37℃)has proved that these physiological indexes post-training had significant improvements ,as compared with those pre-training, suggesting that the combined training could raise heat-tolerance and was superior to the SMT in improving acquired heat acclimatization in same training duration and times , and to the SCT in regulating body temperature and cardiovascular function and in prolonging heat tolerance duration.展开更多
文摘This study aimed to determine the appropriate nutritional intakes and dietary habits of high school-aged cross-country skiers and speed skaters. The subjects, all high school students from N Prefecture, included 18 male cross-country skiers, 5 male speed skaters, 10 female cross-country ski players and 4 female speed skaters. Physical measurements, food intake frequency survey results, bone mineral density and exercise stress test outcomes, and lactic acid measurements were evaluated. Female athletes in both sports had higher body fat percentages relative to the average range stated for female athletes. Male speed skaters had a significantly higher maximum oxygen in-take than that male cross-country skiers did. By contrast, this parameter did not differ significantly among female athletes. A negative correlation was observed between the fat free mass and muscle mass, and a positive correlation was observed among the body fat percentage, fat percentage, and fat mass. Both male and female athletes had protein intake ratios within the reference ranges. All athletes except male speed skaters had lipid energy ratios that were higher than the upper limit of the reference value. Both male and female athletes also reported carbohydrate energy ratios within the reference ranges, but had cereal energy ratios below the reference values. Athletes should pay attention to the ingestion of various nutrients to ensure a sufficient energy intake. Accordingly, adolescent athletes should consume daily meals containing a good balance of staple foods, main dishes, side dishes, milk and other dairy products, and fruits.
文摘The purpose of this study was to investigate whether eight weeks of aerobic high-intensity interval training with roller ski is effective in cross-country skiers. 10 male （age, 18.28 ± 2.1 years; height, 171.26 ± 4.12 cm; weight 61.39 ± 6.28 kg） and 8 female （age, 16.05 ± 0.3 years; height, 158.3 ± 6.47 cm; weight, 49.34 ± 0.7 kg） junior cross country skiers completed the study. All skiers performed a 2 × 2-kin all-out uphill intervals with roller-skis, 3 times a week, in addition to their traditional training program. Measurements included VO2max （maximal oxygen uptake）, anaerobic power, and also for 2-km roller ski. All values were listed as pre-to post-test mean （± SD）, significant level, and percentage changes （%）. Pre-to post-testing changes in VO2max, anaerobic power, and also 2-kin roller ski performance were significantly higher during all post-test trials in all groups （P 〈 0.005）. With reference to the training effects found in our study, we suggest that the skiers should integrate the roller ski aerobic high-intensity interval uphill models in their training programs for improving performance.
文摘The Tour de Ski(TDS:6-9 sprint and distance races across 9-11 days)represents the most intense competition series of the cross-country(XC)ski season and is characterized by accumulated stress from consecutive days of high-intensity(~85%-160% VO_(2max))racing,travel,cold temperatures and low to moderate altitude(500-1500 m above sea level).Here,nutritional strategies play a key supportive role for optimized health,recovery and performance.This narrative review aims to provide an evidence-based discussion on the energetic demands of the TDS and recommendations for nutritional strate-gies to optimize health and performance of XC skiers during and following the TDS.We highlight several challenges that may arise during the TDS,including the following:poor energy availability(EA)due to decreased appetite or a pressure to maintain a low body weight,suboptimal carbohydrate availability due to a failure to replenish muscle glycogen stores across consecutive-day racing and increased risk of illness due to a combination of factors,including high-intensity racing,poor nutrition,sleep,travel and hygiene.We encourage XC skiers to maintain optimal overall EA across the~1.5-week period,ensure high daily carbohydrate availability,as well as the use of strategies to maintain a healthy immune system.In addition,we include practical guidelines on the management of nutrition support prior to and during the TDS.We recognize that many nutritional questions remain unanswered both in the context of elite XC ski racing and specifically for extreme demands like the TDS that should be addressed in future investigations.
文摘This paper reports the effects of two trainings-5 km cross-country race and 15 min heat-bath on theimprovement of heat-tolerance. All subjects of the training group were asked to perform a training once daily for 10to 12 d within two weeks. The results proved that the cross-country race training both in the artificial hot chamberand on the drill ground of troop could obtain evident training-adaptation. The rectal temperature, heart rate, andsweat volume reduced by 0. 39℃, 13. 2 b/min and 338 g during training in field, respectively. In the same period ofcross-country race training, the normal military exercises, labours and natural heat acclimatization in the summercould only raise slightly the level of heat acclimatization in soldiers. Heat-bath training could reduce rectal temperature by 0. 6℃ during immersion in hot water, however, the level of heat-tolerance in a hot climatic chamber was inferior to that attained by cross-country race, march and running training.
文摘in order to improve the acquired level of heat acclimatization (HA) by training, on the basis of singlemode march training (SMT) or single-mode cross-country race training (SCT) , combined training method of march and cross-country race in the heat was adopted in this experiment ,and the effect of the training on heat tolerance was analyzed. Eight young males were asked to perform a simulated SMT and SCT for 90 min on a treadmill in a hot climate chamber (Td 32. 7℃ , WBGT 28. 4℃ ) once daily for 10 to 12 d within two weeks. The results showed that rectal temperature (Tr) was reduced by 0. 61℃ , heart rate (Hr) by 8. 5 b/min,sweat volume (SV)by 0. 220 kg, physiological strain index (PSI)by 0. 620,systolic pressure (SP)and diastolic pressure (DP) had a little change, pulse pressure (PP) and stroke volume (StV) increased , and cardiac output (CO) decreased a little at the middle stage and increased at the late stage due to Hr change. The standardized bicycle ergometer test (SBE test) in the heat (Td 37℃)has proved that these physiological indexes post-training had significant improvements ,as compared with those pre-training, suggesting that the combined training could raise heat-tolerance and was superior to the SMT in improving acquired heat acclimatization in same training duration and times , and to the SCT in regulating body temperature and cardiovascular function and in prolonging heat tolerance duration.
