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6 min readlearning / running

Run 4 hours after you study: the exercise timing for memory

I run about 5,000 km a year and spend training days in front of a room. For years the run went wherever the calendar left a hole. Guillén Fernández's group at Radboud moved it four hours later on purpose and got more memory out of the same material.

The delayed session beat the one straight after.

Eelco van Dongen's team had 72 participants learn 90 picture-location associations across roughly 40 minutes. The group then split three ways: 35 minutes of interval cycling at up to 80% of maximum heart rate right after the session, the same 35 minutes four hours later, or no exercise at all. Everyone came back 48 hours later for a recall test inside an MRI scanner.

The four-hour group retained more of the associations than the no-exercise group, and their hippocampal activation patterns during retrieval were more consistent. The riders who went straight from the learning room to the bike scored no better than the people who did nothing 1.

Motor skills want the session immediately.

Marc Roig's group at Copenhagen ran the same question on a skill rather than a fact. Forty-eight young subjects practised a visuomotor accuracy-tracking task either before a bout of intense cycling, after it, or after rest. The three groups picked the skill up at the same rate. Retention separated them: both exercise groups held the skill better at 24 hours and at 7 days, and the subjects who rode after practice held it better at 7 days than the ones who rode before 2.

Philipp Wanner, Fang-Hsin Cheng and Simon Steib pooled that literature: 22 studies, 862 participants. Acute exercise improved both sleep-dependent and non-sleep consolidation, while the evidence for any benefit on encoding came up empty. Only the high-intensity bouts beat rest, at short-term and long-term retention tests alike 3.

The two systems run on different clocks. A motor skill consolidates from the moment practice stops, and a hard effort at that moment helps it. A set of facts appears to want a gap first.

Before, during and after, in pooled numbers.

Bilal Qazi and colleagues meta-analysed 42 experiments on acute exercise and long-term episodic memory. Exercise before encoding came in at d = 0.23, carried by free recall at d = 0.40 while cued recall sat at 0.08 and recognition at -0.06. Exercise after encoding came in higher at d = 0.33, this time carried by recognition at d = 0.62 against 0.19 for free recall. Exercise during encoding produced d = -0.04 4.

Paul Loprinzi's group had already put a number on that last condition: studying while you move cost d = -0.12 (95% CI -0.22 to -0.02, p = 0.02). Their moderator analysis pointed at vigorous intensity and at young adults, with the largest gains when the bout fell before encoding or inside the early consolidation window 5.

The before-encoding case has one trial worth reading on its own. Bernward Winter's team put 27 healthy subjects through a randomised crossover: learn a novel vocabulary directly after high-impact anaerobic sprints, after low-impact aerobic running, or after rest. The sprint condition produced 20% faster vocabulary learning than either of the other two, along with the largest rises in BDNF and catecholamines. Sustained BDNF during learning tracked short-term success, dopamine tracked intermediate retention, and epinephrine tracked retention past 8 months 6.

Acute bouts move memory 0.52, training programmes 0.07.

Roig's 2013 review pooled 29 acute and 21 long-term exercise interventions. Acute bouts moved long-term memory by SMD 0.52 (95% CI 0.28 to 0.75, p < 0.0001, N = 20). Training programmes moved it by SMD 0.07 (95% CI -0.13 to 0.26, p = 0.51, N = 22). Short-term memory showed the same asymmetry at a smaller scale, 0.26 for acute against 0.15 for chronic 7. The single session near a learning event does the work; the base mileage sets up the machinery.

Even the flagship chronic-training result is contested. Kirk Erickson's randomised trial put 120 older adults through a year of aerobic walking and measured a 2% increase in anterior hippocampal volume, reversing one to two years of age-related loss and tracking serum BDNF 8. Robert Coen, Brian Lawlor and Rose Anne Kenny wrote to PNAS to point out that the stretching control group improved on the memory task too, while its hippocampal volume shrank, and that the two groups did not differ at one year 9.

The protocol.

  1. For material you will have to recall (vocabulary, names, product facts, a new framework), schedule 20 to 35 minutes of hard cardio about 4 hours after the study block. That is the one delay with a controlled result behind it 1.
  2. For a motor skill (an instrument, a sport technique, anything your hands learn), go hard within minutes of stopping practice. The 7-day advantage sat with the group that rode after 2.
  3. Keep the study block and the session apart. Reading on a treadmill scored d = -0.04 in one pooled estimate 4 and d = -0.12 in another 5.
  4. Make the session hard. Only high-intensity bouts separated from rest in the motor meta-analysis 3, and sprints beat easy running by 20% on vocabulary 6.
  5. If the run has to come first, put the learning immediately after it and expect free recall to gain more than recognition 4. Reverse the expectation when the run comes after: recognition gained most there, at d = 0.62.
  6. Cap it around 35 minutes. Every protocol above ran between a set of sprints and 35 minutes of intervals, so longer sessions are untested rather than better.
  7. Treat your base training as separate. Pooled chronic programmes moved long-term memory by 0.07 with p = 0.51 7, so 5,000 km a year buys fitness and buys nothing here on its own.
  8. Test it on your own material. Take two study blocks of the same kind a week apart, add the delayed session to one, and score a cold recall test 48 hours later on both. That is van Dongen's interval, and it is the only comparison that tells you whether your memory behaves like the 72 people in his scanner 1.

My training days end around 17:00, which puts the run four to five hours after the morning block and hours before anything I study at night. That is the schedule I now keep on purpose, and the morning material is the part I am testing it on.

Sources.

  1. van Dongen, E. V., Kersten, I. H. P., Wagner, I. C., Morris, R. G. M., & Fernández, G. (2016). Physical exercise performed four hours after learning improves memory retention and increases hippocampal pattern similarity during retrieval. Current Biology, 26(13), 1722-1727. doi.org/10.1016/j.cub.2016.04.071
  2. Roig, M., Skriver, K., Lundbye-Jensen, J., Kiens, B., & Nielsen, J. B. (2012). A single bout of exercise improves motor memory. PLoS ONE, 7(9), e44594. doi.org/10.1371/journal.pone.0044594
  3. Wanner, P., Cheng, F. H., & Steib, S. (2020). Effects of acute cardiovascular exercise on motor memory encoding and consolidation: a systematic review with meta-analysis. Neuroscience & Biobehavioral Reviews, 116, 365-381. doi.org/10.1016/j.neubiorev.2020.06.018
  4. Qazi, B., Schmid, J., Gridley, N., Lambourne, K., Daly-Smith, A., & Tomporowski, P. D. (2024). The effects of acute exercise on long-term episodic memory: a systematic review and meta-analysis. Frontiers in Cognition, 3, 1367569. doi.org/10.3389/fcogn.2024.1367569
  5. Loprinzi, P. D., Blough, J., Crawford, L., Ryu, S., Zou, L., & Li, H. (2019). The temporal effects of acute exercise on episodic memory function: systematic review with meta-analysis. Brain Sciences, 9(4), 87. doi.org/10.3390/brainsci9040087
  6. Winter, B., Breitenstein, C., Mooren, F. C., Voelker, K., Fobker, M., Lechtermann, A., Krueger, K., Fromme, A., Korsukewitz, C., Flöel, A., & Knecht, S. (2007). High impact running improves learning. Neurobiology of Learning and Memory, 87(4), 597-609. doi.org/10.1016/j.nlm.2006.11.003
  7. Roig, M., Nordbrandt, S., Geertsen, S. S., & Nielsen, J. B. (2013). The effects of cardiovascular exercise on human memory: a review with meta-analysis. Neuroscience & Biobehavioral Reviews, 37(8), 1645-1666. doi.org/10.1016/j.neubiorev.2013.06.012
  8. Erickson, K. I., Voss, M. W., Prakash, R. S., Basak, C., Szabo, A., Chaddock, L., et al. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017-3022. doi.org/10.1073/pnas.1015950108
  9. Coen, R. F., Lawlor, B. A., & Kenny, R. (2011). Failure to demonstrate that memory improvement is due either to aerobic exercise or increased hippocampal volume. Proceedings of the National Academy of Sciences, 108(18), E89. doi.org/10.1073/pnas.1102593108

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