Nuuttila Olli-Pekka, Laatikainen-Raussi Vesa, Vohlakari Krista, Laatikainen-Raussi Iida, Ihalainen Johanna K
Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
The UKK Institute for Health Promotion Research, Kaupinpuistonkatu 1, 33500, Tampere, Finland.
Eur J Appl Physiol. 2025 Mar;125(3):697-705. doi: 10.1007/s00421-024-05631-y. Epub 2024 Oct 9.
Recent studies have suggested that the capability to resist deterioration of physiological characteristics could be an independent factor contributing to endurance performance. This study aimed at investigating whether prolonged low-intensity exercise induces shifts in the lactate threshold, and whether fatigue-induced changes differ between the sexes.
A total of 31 (15 females) recreational runners performed an incremental treadmill test and a 90-min low-intensity exercise (LIT90) on two separate occasions. The LIT90 was performed at 90% of the first lactate threshold speed (LT1v), derived from the incremental treadmill test. The LT1v was determined from a 5-stage (3 min) submaximal threshold test (SubmaxLT), performed before and after LIT90. The SubmaxLTs were followed by a 10/5 reactivity jump test. Respiratory gases, heart rate (HR), and HR-derived detrended fluctuation analysis alpha 1 (DFA-a1) were assessed every 15 min during the LIT90.
A significant decrease (p < 0.01) was observed in the LT1v in females (- 5.8 ± 4.4%) and in males (- 5.3 ± 6.4%). The HR increased (p < 0.001) similarly in females (5.9 ± 3.1%) and in males (5.5 ± 3.6%) during the LIT90, while energy expenditure increased (3.1 ± 4.5%, p = 0.013) in females but remained unchanged in males (0.9 ± 3.1%). Change in DFA-a1 during the LIT90 was the only marker that correlated significantly with the relative change of LT1v (r = 0.463, p = 0.013).
LIT90 induced significant decreases in the LT1v, and the changes were comparable between sexes. DFA-a1 could be a potential intra-session marker of durability.
近期研究表明，抵抗生理特征恶化的能力可能是影响耐力表现的一个独立因素。本研究旨在调查长时间低强度运动是否会导致乳酸阈发生变化，以及疲劳引起的变化在性别之间是否存在差异。
共有31名（15名女性）业余跑步者在两个不同的时间段分别进行了递增式跑步机测试和90分钟的低强度运动（LIT90）。LIT90以递增式跑步机测试得出的第一个乳酸阈速度（LT1v）的90%进行。LT1v通过在LIT90前后进行的5阶段（3分钟）次最大阈测试（SubmaxLT）来确定。SubmaxLT之后进行10/5反应性跳跃测试。在LIT90期间，每15分钟评估一次呼吸气体、心率（HR）以及基于心率的去趋势波动分析α1（DFA-a1）。
女性（-5.8±4.4%）和男性（-5.3±6.4%）的LT1v均出现显著下降（p<0.01）。在LIT90期间，女性（5.9±3.1%）和男性（5.5±3.6%）的心率均出现类似的增加（p<0.001），而女性的能量消耗增加（3.1±4.5%，p=0.013），男性则保持不变（0.9±3.1%）。LIT90期间DFA-a1的变化是唯一与LT1v的相对变化显著相关的指标（r=0.463，p=0.013）。
LIT90导致LT1v显著下降，且性别之间的变化具有可比性。DFA-a1可能是耐力的一个潜在的运动过程中的标志物。
