Effects of high-intensity interval training on blood lactate levels and cognition in healthy adults: protocol for systematic review and network meta-analyses

Abstract

Background High-intensity interval training (HIIT) has shown to confer cognitive benefits in healthy adults, via a mechanism purportedly driven by the exercise metabolite lactate. However, our understanding of the exercise parameters (e.g., work interval duration, session volume, work-to-rest ratio) that evoke a peak blood lactate response in healthy adults is limited. Moreover, evidence relating HIIT-induced blood lactate and cognitive performance has yet to be reviewed and analyzed. The primary objective of this systematic review is to use network meta-analyses to compare the relative impact of different HIIT work-interval durations, session volumes, and work-to-rest ratios on post-exercise blood lactate response in healthy adults. The secondary objective is to determine the relationship between HIIT-induced blood lactate and acute post-HIIT cognitive performance. Methods A systematic review is being conducted to identify studies measuring blood lactate response following one session of HIIT in healthy adults. The search was carried out in (1) MEDLINE, (2) EMBASE, (3) Cochrane Central Register of Controlled Trials, (4) Sport Discus, and (5) Cumulative Index to Nursing and Allied Health Literature Plus with Full Text (CINAHL+). After abstract and full-text screening, two reviewers will independently extract data on key outcomes variables and complete risk of bias assessment using the Cochrane Risk of Bias Tool and the Risk of Bias in Non-Randomized Studies of Interventions tool. Network meta-analyses will be used to generate estimates of the comparative effectiveness of blood lactate on cognitive outcomes using corresponding rankings for each work-interval duration, session volume, and work-to-rest ratio category. Where applicable, meta-regressions analyses will be performed to test the relationship between changes in the blood lactate and changes in cognitive performance. Analyses will be conducted using MetaInsight Software. Discussion This study will provide evidence on how to structure a HIIT protocol to elicit peak blood lactate response in healthy adults and will increase our understanding of the relationship between HIIT-induced blood lactate response and associated cognitive benefits. Systematic review registration PROSPERO CRD42020204400

Measuring the Immediate Effects of High-Intensity Functional Training on Motor, Cognitive and Physiological Parameters in Well-Trained Adults

“…By analyzing the results related to the physiological parameters, we found a significant increase in the level of lactate starting from the first post-exercise session, and a further increase after the third one. Compared to other studies [4,38,39], the slightly high values in the PRE session can be ascribed to the presence of the warm-up session. The level of lactate after each HIFT repetition showed lower values than the ones reported in [38]; this may be due to the methodology used to acquire the level of lactate.…”

“…In fact, by considering the trend of the statistical results, we can speculate that accuracy in the execution of cognitive tasks does not vary after the third repetition, suggesting that the necessity of six repetitions is an overestimation in regard to planning training programs. This finding could be used as a starting point to solve one of the most unanswered questions when designing training, i.e., the ideal number of circuit repetitions; in fact, Jacob et al found a strong connection between cognitive performance and the duration of an exercise program [4].…”

“…Among exercise programs, high-intensity interval training (HIIT) has been recognized as a valuable protocol and become very popular in the last decade [3]. HIIT is characterized by repeated short-to-long bouts of intensive exercises [4]. Due to its potentiality, HIIT has been already used both in clinical settings, i.e., for the prevention of and/or to treat cardiac disorders [3], and in sports, i.e., to improve the performance of elite athletes [5].…”

Effectiveness of high‐intensity interval training on peripheral brain‐derived neurotrophic factor in adults: A systematic review and network meta‐analysis

“…Lactate synthesized as a result of exercise is used to satisfy the energy demands of neurons 68 and, as a neuronal signaling molecule, to increase BDNF expression 69 . Therefore, HIIT programs would result in a peak accumulation of lactate in the blood, which is responsible for augmented BDNF expression in the brain 68 …”

“…65 This myokine accumulates in the blood during acute exercise depending on the intensity and duration of the exercise and is able to cross the blood-brain barrier. 66,67 Lactate synthesized as a result of exercise is used to satisfy the energy demands of neurons 68 and, as a neuronal signaling molecule, to increase BDNF expression. 69 Therefore, HIIT programs would result in a peak accumulation of lactate in the blood, which is responsible for augmented BDNF expression in the brain.…”