Rakovac Marija, Šentija Davor, Maršić Tošo, Babić Vesna
University of Zagreb Faculty of Kinesiology, Zagreb, Croatia.
Faculty of Science and Education University of Mostar, Department for Kinesiology, Mostar, Bosnia and Herzegovina.
PeerJ. 2025 Jul 17;13:e19686. doi: 10.7717/peerj.19686. eCollection 2025.
We investigated core body temperature (CBT) during a graded exercise test (GXT) in comparison with gas exchange dynamics.
Thirty-two active males performed a treadmill GXT (0.5 km/h increments every 30 seconds, 1.5% incline) until exhaustion. Gas exchange data and rectal temperature (T) were continuously registered. Ten participants repeated the test for reliability assessment. The first and second gas exchange thresholds (VT and VT) were determined by the simplified V-slope method, while CBT dynamics and eventual temperature thresholds (TT and TT) were assessed according to the criteria defined in this study. Three independent evaluators determined gas exchange and temperature thresholds.
In 29 subjects, T increase was best fitted with a 3-phase segmented model of successively steeper slopes, with a linear relationship in all three segments (17 subjects), or in two segments, with a quadratic relationship for the remaining segment (12 subjects). The between-segment intersection points were considered as TT and TT. In three participants, T was best fitted with a two-segment, single-breakpoint (TT or TT) model. The evaluators' objectivity was satisfactory for VT (α = 0.786), very high for TT (α = 0.941) and VT (α = 0.948). TT and VT were moderately correlated ( = 0.41, = 0.021) while VT and TT were highly correlated ( = 0.78, < 0.001) showing a small, yet statistically significant difference (12.95 ± 1.9 vs 13.43 ± 1.7 km/h, = 0.039). However, test-retest reliability was low.
The breakpoints in CBT increase observed during graded running may represent transitions between the three intensity domains of physical activity.
我们在分级运动试验（GXT）期间研究了核心体温（CBT），并与气体交换动力学进行了比较。
32名活跃男性进行了跑步机GXT（每30秒速度增加0.5 km/h，坡度为1.5%）直至力竭。连续记录气体交换数据和直肠温度（T）。10名参与者重复该测试以进行可靠性评估。通过简化的V斜率法确定第一和第二气体交换阈值（VT和VT），而CBT动力学和最终温度阈值（TT和TT）则根据本研究中定义的标准进行评估。三名独立评估者确定气体交换和温度阈值。
在29名受试者中，T的升高最适合用斜率逐渐变陡的三相分段模型来拟合，在所有三个阶段均呈线性关系（17名受试者），或在两个阶段呈线性关系，其余阶段呈二次关系（12名受试者）。各阶段之间的交点被视为TT和TT。在三名参与者中，T最适合用两段、单断点（TT或TT）模型来拟合。评估者对VT的客观性令人满意（α = 0.786），对TT（α = 0.941）和VT（α = 0.948）的客观性非常高。TT和VT呈中度相关（ = 0.41， = 0.021），而VT和TT高度相关（ = 0.78， < 0.001），显示出虽小但具有统计学意义的差异（12.95 ± 1.9 vs 13.43 ± 1.7 km/h， = 0.039）。然而，重测信度较低。
在分级跑步过程中观察到的CBT升高的断点可能代表身体活动三个强度域之间的转变。
