Key result
A 90-minute low-intensity running exercise significantly decreased the first lactate threshold speed by 5.8% in females and 5.3% in males, with no significant difference between sexes.
Why the study?
Recent studies suggested that the capability to resist physiological deterioration may independently contribute to endurance performance, prompting investigation into whether prolonged low-intensity exercise shifts the lactate threshold and whether fatigue-induced changes differ by sex.
Does 90-min low-intensity exercise reduce the running speed at the lactate threshold in recreational runners?
Does 90-min low-intensity exercise reduce the running speed at the lactate threshold in recreational runners?
Effect estimate: -5.8% in females, -5.3% in males
p-value: p=<0.01
Prolonged low-intensity running induces significant decreases in the lactate threshold speed comparably between sexes, with DFA-a1 serving as a potential intra-session marker of this fatigue.
PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.
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Nuuttila et al. (2024) studied Healthy recreational runners (n=31). 90-min low-intensity exercise (LIT90) vs. Pre-exercise baseline was evaluated on Change in first lactate threshold speed (LT1v) (-5.8% in females, -5.3% in males, p=<0.01). A 90-minute low-intensity running exercise significantly decreased the first lactate threshold speed by 5.8% in females and 5.3% in males, with no significant difference between sexes.
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