Fischer Jonas, Hävecker Finn, Ji Sanghyeon, Wahl Patrick, Keller Sebastian
Department of Exercise Physiology, German Sport University, Cologne, Germany.
German Research Centre of Elite Sport, German Sport University, Cologne, Germany.
Eur J Appl Physiol. 2025 Apr 12. doi: 10.1007/s00421-025-05744-y.
Understanding physiological determinants of lactate threshold 2 (LT2) is crucial for tracking adaptations and deriving individualized training recommendations in cycling. Therefore, the study investigated: 1. the accuracy of modeling power output at LT2 in young athletes of both sexes using maximal oxygen uptake ( ), fractional utilization of (% ), and oxygen cost of cycling (Cc); 2. the influence of Cc determination on the model accuracy; 3. the influence of the model predictors and inclusion of maximal lactate accumulation rate ( ) on power at LT2 depending on sex.
Eighty-three cyclists and triathletes (22 females, 61 males; age [median and IQR]: 14.6 [13.8-17.6] years, [mean ± SD]: 59.2 ± 6.5 mL⋅kg⋅min) performed an incremental test to determine power at LT2, % at LT2, and Cc (assessed at 3 W⋅kg, 75% and 90% LT2).
Modeled and experimentally determined power at LT2 demonstrated excellent agreement for all, male and female athletes (ICC 0.961), with Cc at 90% LT2 providing the highest accuracy (ICC 0.986). The three physiological determinants explained 98% of the variance in power at LT2, with the largest unique contribution from (62 and 67% of total ), followed by Cc (8 and 34%) and % at LT2 (5 and 12%) in males and females, respectively, while did not improve the regression.
% at LT2 and Cc accurately predict power at LT2 in young cycling athletes independent of sex, with determination of Cc at 90% LT2 providing the highest accuracy. While contributes most to LT2 in both sexes, Cc appears more important in young females.
了解乳酸阈2（LT2）的生理决定因素对于追踪适应性变化和制定自行车运动的个性化训练建议至关重要。因此，本研究调查了：1. 使用最大摄氧量（ ）、 的分数利用率（% ）和自行车运动的氧耗（Cc）对男女青年运动员LT2时的功率输出进行建模的准确性；2. Cc测定对模型准确性的影响；3. 模型预测因子以及最大乳酸积累率（ ）的纳入对不同性别的LT2功率的影响。
83名自行车运动员和铁人三项运动员（22名女性，61名男性；年龄[中位数和四分位距]：14.6[13.8 - 17.6]岁， [平均值±标准差]：59.2±6.5 mL·kg·min）进行递增测试，以确定LT2时的功率、LT2时的% 和Cc（在3 W·kg、75% 和90% LT2时评估）。
LT2时的建模功率和实验测定功率在所有男女运动员中均显示出极好的一致性（组内相关系数ICC 0.961），90% LT2时的Cc提供了最高的准确性（ICC 0.986）。这三个生理决定因素解释了LT2时功率变化的98%，男性中最大的独特贡献来自 （占总 的62%和67%），其次是Cc（8%和34%）以及LT2时的% （5%和12%），而 并未改善回归。
LT2时的% 和Cc可独立于性别准确预测青年自行车运动员LT2时的功率，90% LT2时的Cc测定提供了最高的准确性。虽然 对男女两性的LT2贡献最大，但Cc在年轻女性中似乎更为重要。
