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How High-Intensity Exercise Affects Brain Health. A Look at BDNF and Neuroprotection.

Writer's picture: Alastair HuntAlastair Hunt
BDNF HIIT workouts brain cognitive health

Exercise is widely recognised for its role in promoting physical and mental well-being. Beyond its benefits for heart health and metabolism, growing research suggests that exercise plays a vital role in protecting the brain against cognitive decline. One key mechanism involves brain-derived neurotrophic factor (BDNF), a protein essential for neuroplasticity, learning and memory. High-intensity exercise, whether running or cycling, has been linked to increased BDNF levels, potentially enhancing brain resilience and reducing the risk of neurodegenerative diseases.


As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Work up to high-intensity workouts gradually, build an appropriate base level of fitness first. Links to all studies at the bottom of the page.


This article reviews three recent studies examining the relationship between high-intensity exercise and BDNF. While the findings support the potential of high-intensity training for brain health, they also reveal inconsistencies, suggesting that factors such as exercise duration, individual differences and training protocols influence BDNF responses.

 

The Role of Exercise Intensity in Neuroprotection


BDNF is a critical protein that supports neuronal survival, synaptic plasticit, and cognitive function. It is produced primarily in the brain but also circulates in the bloodstream, where it influences various tissues, including muscles. While exercise is known to boost BDNF levels, the question remains: does high-intensity exercise provide greater benefits compared to moderate-intensity training?


Study 1: High-Intensity Training and BDNF Responses

Murawska-Ciałowicz et al. conducted a nine-week study comparing four types of high-intensity training - functional training (HIFT), interval training (HIIT), power training (HIPT), and endurance training (HIET) - to measure their effects on BDNF levels in healthy men.


Key findings:


  • Resting BDNF levels did not increase after nine weeks of training.

  • After an aerobic fitness test (Graded Exercise Test), BDNF increased significantly in HIIT and HIFT groups but not in the endurance group.

  • After an anaerobic test (Wingate Anaerobic Test), BDNF decreased in most groups, suggesting that short bursts of all-out effort might temporarily suppress BDNF levels.


These results suggest that while high-intensity exercise can boost BDNF acutely, prolonged high-intensity training may lead to fluctuations, possibly due to metabolic stress, muscle repair demands, or hormonal regulation.


Try it yourself: If you’d like to replicate the workouts in this study...


HIIT Group


  • 6 rounds of 90 seconds of intense work - cycling or running at 85% of max heart rate.

  • 90 seconds of active recovery between rounds.

  • Sessions lasted 53 minutes, including warm-up and cooldown.


HIFT Group


  • Strength-based functional movements performed at high intensity.

  • Workouts varied but included Olympic lifts (e.g. squats, deadlifts) and conditioning exercises.

  • 8 sets of 30 seconds of high-intensity exercise with 150 seconds of rest.

  • Total session duration: approx 59 minutes.

 
Study 2: Meta-Analysis of High-Intensity Exercise and BDNF

A systematic review and meta-analysis by Fernández-Rodríguez et al. assessed 22 studies examining the immediate effects of high-intensity exercise (HIE) on BDNF levels. The authors found that:


  • HIE caused a significant, immediate increase in BDNF compared to both non-exercise and light-intensity exercise.

  • HIE did not show a significant advantage over moderate-intensity exercise.

  • The effects were independent of exercise duration or baseline fitness level.


This analysis supports the idea that high-intensity exercise can rapidly elevate BDNF levels, but the differences compared to moderate exercise remain unclear. The authors suggested that exercise intensity may not be the only factor influencing BDNF responses—individual differences and other physiological mechanisms likely play a role.


Training method recommendation: Since multiple studies showed immediate BDNF spikes post-exercise, incorporating HIIT-style workouts into your week - even if for just 20–30 minutes - could be beneficial.

 
Study 3: HIIT and BDNF - A Systematic Review

Mielniczek and Aune reviewed 12 studies focusing specifically on high-intensity interval training (HIIT) and BDNF. While most studies reported significant increases in BDNF following HIIT, results varied based on protocol differences and participant characteristics:


  • Some studies found only short-term increases in BDNF that returned to baseline quickly.

  • Others showed no change or even decreases in BDNF, particularly in long-term HIIT interventions.

  • The authors highlighted the need for standardised HIIT protocols to determine the most effective approach for boosting BDNF.


These findings reinforce that HIIT has potential cognitive benefits but also raises questions about the sustainability of BDNF increases and whether adaptations occur over time that reduce its long-term effects.


Try it yourself. Cycling HIIT (as used in several studies):


  • Warm-up: 5 minutes of light cycling.

  • 10 rounds of 30 seconds of sprint cycling at 90% max effort.

  • 60 seconds of slow cycling in between.

  • Cooldown: 5 minutes of easy pedalling.

 

Why Do BDNF Responses Differ?


The mixed findings across these studies suggest that BDNF responses to high-intensity exercise are complex and influenced by multiple factors:


  • Exercise Modality: Studies using endurance-based high-intensity training (e.g., cycling or running) often reported different results than those using resistance-based protocols.


  • Session Duration: Some evidence suggests that short bouts of high intensity exercise may boost BDNF, but prolonged or repeated high-intensity efforts might lead to fluctuating or declining levels.


  • Hormonal and Metabolic Stress: Intense training can elevate stress hormones like cortisol, which may counteract BDNF increases. Additionally, BDNF may be used for tissue repair rather than remaining elevated in circulation.


  • Baseline Fitness Levels: Trained individuals may experience smaller BDNF increases than untrained individuals, potentially due to adaptations that make their bodies more efficient at regulating neurotrophic factors.


  • Individual Variation: Genetic factors, sleep, diet, and overall health status all play roles in determining how an individual responds to exercise-induced BDNF changes.

 

Final Thoughts


The evidence reviewed here highlights that high-intensity exercise can acutely increase BDNF levels, particularly when compared to low-intensity exercise or rest. However, the long-term effects of HIIT and other high-intensity protocols on brain health remain uncertain.


  • Short-term: A single session of high-intensity exercise is likely to boost BDNF.


  • Long-term: Repeated high-intensity training may lead to fluctuations in BDNF levels, potentially due to metabolic stress, adaptation or hormonal regulation.


  • Comparison to moderate-intensity exercise: While high-intensity exercise seems to provide a clear acute benefit, its long-term advantages over moderate-intensity exercise remain unclear.


Given these findings, incorporating a mix of exercise intensities - rather than exclusively relying on high-intensity training - may be the best approach for optimising brain health. Of course, regular HIIT training also provides benefits for cardiac health and longevity. Future research should aim to determine the most effective exercise "dose" for maintaining elevated BDNF levels and promoting long-term cognitive benefits. Diet also matters, the MIND diet was formulated by scientists to optimise brain health outcomes. And studies on Singaporean dietary patterns have also shown similar positive outcomes.


For most people, improving health is about finding motivation and prioritising self-care with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle, The Whole Health Practice is here to help.


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Stay Healthy,


Alastair


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Studies and Resources


The studies in review...


Mielniczek M, Aune TK. The Effect of High-Intensity Interval Training (HIIT) on Brain-Derived Neurotrophic Factor Levels (BNDF): A Systematic Review. Brain Sci. 2024 Dec 30;15(1):34. doi: 10.3390/brainsci15010034. PMID: 39851402; PMCID: PMC11764394.


Fernández-Rodríguez R, Álvarez-Bueno C, Martínez-Ortega IA, Martínez-Vizcaíno V, Mesas AE, Notario-Pacheco B. Immediate effect of high-intensity exercise on brain-derived neurotrophic factor in healthy young adults: A systematic review and meta-analysis. J Sport Health Sci. 2022 May;11(3):367-375. doi: 10.1016/j.jshs.2021.08.004. Epub 2021 Sep 1. PMID: 34481089; PMCID: PMC9189701.



Other

Rahmani F, Saghazadeh A, Rahmani M, Teixeira AL, Rezaei N, Aghamollaii V, Ardebili HE. Plasma levels of brain-derived neurotrophic factor in patients with Parkinson disease: A systematic review and meta-analysis. Brain Res. 2019 Feb 1;1704:127-136. doi: 10.1016/j.brainres.2018.10.006. Epub 2018 Oct 6. PMID: 30296429.


Qin XY, Cao C, Cawley NX, Liu TT, Yuan J, Loh YP, Cheng Y. Decreased peripheral brain-derived neurotrophic factor levels in Alzheimer's disease: a meta-analysis study (N=7277). Mol Psychiatry. 2017 Feb;22(2):312-320. doi: 10.1038/mp.2016.62. Epub 2016 Apr 26. PMID: 27113997.




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