# Efectes neurobiològics de l'exercici físic

Els efectes neurobiològics de l'exercici físic son nombrosos i impliquen una àmplia gamma d'efectes interrelacionats sobre l'estructura del cervell, la funció cerebral i la cognició. Un gran nombre d'investigacions en humans demostren que l'exercici aeròbic habitual (per exemple, 30 minuts cada dia) indueix millores persistents en determinades funcions cognitives, alteracions saludables en l'expressió gènica al cervell i formes beneficioses de neuroplasticitat i plasticitat conductual. Alguns d'aquests efectes a llarg termini son: augment del creixement de les neurones, augment de l'activitat neurològica –per exemple, senyalització de c-Fos i factor neurotròfic derivat del cervell (BDNF)–, millor afrontament de l'estrès, millor control cognitiu del comportament, millora de la memòria declarativa, espacial i de treball, i millores estructurals i funcionals en les estructures i vies cerebrals associades amb el control cognitiu i la memòria. Els efectes de l'exercici sobre la cognició tenen implicacions importants en millorar el rendiment acadèmic en nens i estudiants universitaris, millorar la productivitat dels adults, preservar la funció cognitiva durant la vellesa, prevenir o tractar determinats trastorns neurològics i millorar la qualitat de vida en general.
En adults sans, s'ha demostrat que l'exercici aeròbic indueix efectes transitoris sobre la cognició després d'una sola sessió d'exercici i efectes persistents sobre la cognició després de fer exercici regularment durant diversos mesos. Les persones que realitzen regularment exercici aeròbic (p. ex., córrer, trotar, caminar ràpid, nedar i anar en bicicleta) tenen puntuacions més elevades en les proves de funció neuropsicològica i de rendiment que mesuren determinades funcions cognitives, com ara el control de l'atenció, el control inhibitori, la flexibilitat cognitiva i l'actualització i la capacitat de memòria de treball, memòria declarativa, memòria espacial i velocitat de processament de la informació. Els efectes transitoris de l'exercici sobre la cognició inclouen millores en la majoria de les funcions executives (per exemple, atenció, memòria de treball, flexibilitat cognitiva, control inhibitori, resolució de problemes i presa de decisions) i en la velocitat de processament de la informació durant un període de fins a 2 hores després de fer exercici.
L'exercici aeròbic indueix efectes a curt i llarg termini sobre l'estat d'ànim i els estats emocionals en promoure l'afecte positiu, inhibir l'afecte negatiu i disminuir la resposta biològica a l'estrès psicològic agut. A curt termini, l'exercici aeròbic funciona com antidepressiu i euforitzant, mentre que l'exercici constant produeix millores generals en l'estat d'ànim i l'autoestima.
L'exercici aeròbic regular millora els símptomes associats a una sèrie de patologies del sistema nerviós central i es pot utilitzar com a teràpia complementària per a aquests trastorns. Hi ha proves clares de l'eficàcia del tractament a través de l'exercici per al trastorn depressiu major i el trastorn per dèficit d'atenció amb hiperactivitat. La guia de pràctica clínica de l'Acadèmia Americana de Neurologia estableix respecte a un deteriorament cognitiu lleu que els metges han de recomanar exercici regular (dues vegades per setmana) a les persones que han estat diagnosticades. Les revisions de l'evidència clínica també donen suport a l'ús de l'exercici com a teràpia complementària per a determinats trastorns neurodegeneratius, especialment la malaltia d'Alzheimer i la malaltia de Parkinson. L'exercici regular també s'associa amb un menor risc de desenvolupar trastorns neurodegeneratius. Un gran conjunt d'evidències preclíniques i evidències clíniques emergents donen suport a l'ús de l'exercici com a teràpia complementària per al tractament i la prevenció de les drogodependències. També s'ha proposat l'exercici regular com a teràpia complementària per als càncers cerebrals.

## Referències

* 1 2 J Clin Neurol, 11, 3, 01-07-2015, pàg. 212–219. DOI: 10.3988/jcn.2015.11.3.212. PMC: 4507374. PMID: 26174783. «Aerobic physical exercise (PE) activates the release of neurotrophic factors and promotes angiogenesis, thereby facilitating neurogenesis and synaptogenesis, which in turn improve memory and cognitive functions. ... Exercise limits the alteration in dopaminergic neurons in the substantia nigra and contributes to optimal functioning of the basal ganglia involved in motor commands and control by adaptive mechanisms involving dopamine and glutamate neurotransmission.»
* 1 2 Acta Neuropathol., 127, 1, 01-01-2014, pàg. 29–51. DOI: 10.1007/s00401-013-1230-6. PMC: 4255282. PMID: 24366527. «The benefits of regular exercise, physical fitness and sports participation on cardiovascular and brain health are undeniable ... Exercise also enhances psychological health, reduces age-related loss of brain volume, improves cognition, reduces the risk of developing dementia, and impedes neurodegeneration.»
* 1 2 Sports Med, 44, 2, 01-02-2014, pàg. 189–209. DOI: 10.1007/s40279-013-0114-1. PMID: 24163284. «Aerobic physical exercise produces numerous health benefits in the brain. Regular engagement in physical exercise enhances cognitive functioning, increases brain neurotrophic proteins, such as brain-derived neurotrophic factor (BDNF), and prevents cognitive diseases [76–78]. Recent findings highlight a role for aerobic exercise in modulating chromatin remodelers [21, 79–82]. ... These results were the first to demonstrate that acute and relatively short aerobic exercise modulates epigenetic modifications. The transient epigenetic modifications observed due to chronic running training have also been associated with improved learning and stress-coping strategies, epigenetic changes and increased c-Fos-positive neurons ... Nonetheless, these studies demonstrate the existence of epigenetic changes after acute and chronic exercise and show they are associated with improved cognitive function and elevated markers of neurotrophic factors and neuronal activity (BDNF and c-Fos). ... The aerobic exercise training-induced changes to miRNA profile in the brain seem to be intensity-dependent [164]. These few studies provide a basis for further exploration into potential miRNAs involved in brain and neuronal development and recovery via aerobic exercise.»
* 1 2 3 «Physical activity, brain, and cognition». Current Opinion in Behavioral Sciences, 4, 01-08-2015, pàg. 27–32. DOI: 10.1016/j.cobeha.2015.01.005.
* 1 2 «The influence of exercise on cognitive abilities». A: Comprehensive Physiology. 3, gener 2013, p. 403–428. DOI 10.1002/cphy.c110063. ISBN 9780470650714.
* ↑ Neurobiol. Aging, 35 Suppl 2, 01-09-2014, pàg. S20–528. DOI: 10.1016/j.neurobiolaging.2014.03.034. PMC: 4094356. PMID: 24952993.
* 1 2 Psychon Bull Rev, 20, 1, 01-02-2013, pàg. 73–86. DOI: 10.3758/s13423-012-0345-4. PMID: 23229442 [Consulta: free].
* ↑ Neuroscientist, 18, 1, 2012, pàg. 82–97. DOI: 10.1177/1073858410397054. PMC: 3575139. PMID: 21531985.
* 1 2 Front Hum Neurosci, 8, 2014, pàg. 747. DOI: 10.3389/fnhum.2014.00747. PMC: 4179677. PMID: 25324754 [Consulta: free].
* 1 2 Psychiatry Res., 241, 01-07-2016, pàg. 47–54. DOI: 10.1016/j.psychres.2016.04.054. PMID: 27155287. «Exercise has established efficacy as an antidepressant in people with depression. ... Exercise significantly improved physical and psychological domains and overall QoL. ... The lack of improvement among control groups reinforces the role of exercise as a treatment for depression with benefits to QoL.»
* ↑ International Scholarly Research Notices, 2014, 01-11-2014, pàg. 257248. DOI: 10.1155/2014/257248. PMC: 4897547. PMID: 27351018 [Consulta: free]. «Research investigating the effects of exercise on older adults has primarily focused on brain structural and functional changes with relation to cognitive improvement. In particular, several cross-sectional and intervention studies have shown a positive association between physical activity and cognition in older persons [86] and an inverse correlation with cognitive decline and dementia [87]. Older adults enrolled in a 6-month aerobic fitness intervention increased brain volume in both gray matter (anterior cingulate cortex, supplementary motor area, posterior middle frontal gyrus, and left superior temporal lobe) and white matter (anterior third of corpus callosum) [88]. In addition, Colcombe and colleagues showed that older adults with higher cardiovascular fitness levels are better at activating attentional resources, including decreased activation of the anterior cingulated cortex. One of the possible mechanisms by which physical activity may benefit cognition is that physical activity maintains brain plasticity, increases brain volume, stimulates neurogenesis and synaptogenesis, and increases neurotrophic factors in different areas of the brain, possibly providing reserve against later cognitive decline and dementia [89, 90].»
* ↑ Mandolesi, Laura; Polverino, Arianna; Montuori, Simone; Foti, Francesca; Ferraioli, Giampaolo Frontiers in Psychology, 9, 27-04-2018, pàg. 509. DOI: 10.3389/fpsyg.2018.00509. PMC: 5934999. PMID: 29755380 [Consulta: free].
* 1 2 3 4 Basso JC, Suzuki WA Brain Plasticity, 2, 2, 01-03-2017, pàg. 127–152. DOI: 10.3233/BPL-160040. PMC: 5928534. PMID: 29765853 [Consulta: free]. «A large collection of research in humans has shown that a single bout of exercise alters behavior at the level of affective state and cognitive functioning in several key ways. In terms of affective state, acute exercise decreases negative affect, increases positive affect, and decreases the psychological and physiological response to acute stress [28]. These effects have been reported to persist for up to 24 hours after exercise cessation [28, 29, 53]. In terms of cognitive functioning, acute exercise primarily enhances executive functions dependent on the prefrontal cortex including attention, working memory, problem solving, cognitive flexibility, verbal fluency, decision making, and inhibitory control [9]. These positive changes have been demonstrated to occur with very low to very high exercise intensities [9], with effects lasting for up to two hours after the end of the exercise bout (Fig. 1A) [27]. Moreover, many of these neuropsychological assessments measure several aspects of behavior including both accuracy of performance and speed of processing. McMorris and Hale performed a meta-analysis examining the effects of acute exercise on both accuracy and speed of processing, revealing that speed significantly improved post-exercise, with minimal or no effect on accuracy [17]. These authors concluded that increasing task difficulty or complexity may help to augment the effect of acute exercise on accuracy. ... However, in a comprehensive meta-analysis, Chang and colleagues found that exercise intensities ranging from very light (<50% MHR) to very hard (>93% MHR) have all been reported to improve cognitive functioning [9].»
* ↑ «Relationship between physical activity and cognitive function in apparently healthy young to middle-aged adults: A systematic review». J. Sci. Med. Sport, 19, 8, 01-08-2016, pàg. 616–628. DOI: 10.1016/j.jsams.2015.09.003. PMID: 26552574. «A range of validated platforms assessed CF across three domains: executive function (12 studies), memory (four studies) and processing speed (seven studies). ... In studies of executive function, five found a significant ES in favour of higher PA, ranging from small to large. Although three of four studies in the memory domain reported a significant benefit of higher PA, there was only one significant ES, which favoured low PA. Only one study examining processing speed had a significant ES, favouring higher PA. CONCLUSIONS: A limited body of evidence supports a positive effect of PA on CF in young to middle-aged adults. Further research into this relationship at this age stage is warranted. ... Significant positive effects of PA on cognitive function were found in 12 of the 14 included manuscripts, the relationship being most consistent for executive function, intermediate for memory and weak for processing speed.»
* ↑ (en portuguès) Arq Bras Endocrinol Metabol, 52, 4, 01-06-2008, pàg. 589–598. DOI: 10.1590/S0004-27302008000400004. PMID: 18604371 [Consulta: free]. «Interestingly, some symptoms of OT are related to beta-endorphin (beta-end(1-31)) effects. Some of its effects, such as analgesia, increasing lactate tolerance, and exercise-induced euphoria, are important for training.»
* ↑ Cereb. Cortex, 18, 11, 2008, pàg. 2523–2531. DOI: 10.1093/cercor/bhn013. PMID: 18296435 [Consulta: free]. «The runner's high describes a euphoric state resulting from long-distance running.»
* 1 2 Scand J Med Sci Sports, 24, 2, 2014, pàg. 259–272. DOI: 10.1111/sms.12050. PMID: 23362828.
* ↑ J Psychiatr Res, 60C, 01-10-2014, pàg. 56–64. DOI: 10.1016/j.jpsychires.2014.10.003. PMC: 4314337. PMID: 25455510. «Consistent evidence indicates that exercise improves cognition and mood, with preliminary evidence suggesting that brain-derived neurotrophic factor (BDNF) may mediate these effects. The aim of the current meta-analysis was to provide an estimate of the strength of the association between exercise and increased BDNF levels in humans across multiple exercise paradigms. We conducted a meta-analysis of 29 studies (N = 1111 participants) examining the effect of exercise on BDNF levels in three exercise paradigms: (1) a single session of exercise, (2) a session of exercise following a program of regular exercise, and (3) resting BDNF levels following a program of regular exercise. Moderators of this effect were also examined. Results demonstrated a moderate effect size for increases in BDNF following a single session of exercise (Hedges' g = 0.46, p < 0.001). Further, regular exercise intensified the effect of a session of exercise on BDNF levels (Hedges' g = 0.59, p = 0.02). Finally, results indicated a small effect of regular exercise on resting BDNF levels (Hedges' g = 0.27, p = 0.005). ... Effect size analysis supports the role of exercise as a strategy for enhancing BDNF activity in humans.»
* ↑ Prev Chronic Dis, 10, 2013, pàg. E174. DOI: 10.5888/pcd10.130010. PMC: 3809922. PMID: 24157077. «This omission is relevant, given the evidence that aerobic-based physical activity generates structural changes in the brain, such as neurogenesis, angiogenesis, increased hippocampal volume, and connectivity (12,13). In children, a positive relationship between aerobic fitness, hippocampal volume, and memory has been found (12,13). ... Mental health outcomes included reduced depression and increased self-esteem, although no change was found in anxiety levels (18). ... This systematic review of the literature found that [aerobic physical activity (APA)] is positively associated with cognition, academic achievement, behavior, and psychosocial functioning outcomes. Importantly, Shephard also showed that curriculum time reassigned to APA still results in a measurable, albeit small, improvement in academic performance (24). ... The actual aerobic-based activity does not appear to be a major factor; interventions used many different types of APA and found similar associations. In positive association studies, intensity of the aerobic activity was moderate to vigorous. The amount of time spent in APA varied significantly between studies; however, even as little as 45 minutes per week appeared to have a benefit.»
* ↑ Acta Paediatr., 103, 7, 01-07-2014, pàg. 709–14. DOI: 10.1111/apa.12628. PMID: 24612421. «The present review summarises the impact of exercise interventions (1–10 weeks in duration with at least two sessions each week) on parameters related to ADHD in 7-to 13-year-old children. We may conclude that all different types of exercise (here yoga, active games with and without the involvement of balls, walking and athletic training) attenuate the characteristic symptoms of ADHD and improve social behaviour, motor skills, strength and neuropsychological parameters without any undesirable side effects. Available reports do not reveal which type, intensity, duration and frequency of exercise is most effective in this respect and future research focusing on this question with randomised and controlled long-term interventions is warranted.»
* ↑ Int Psychogeriatr, 26, 1, 01-01-2014, pàg. 9–18. DOI: 10.1017/S1041610213001385. PMID: 23962667. «Six RCTs were identified that exclusively considered the effect of exercise in AD patients. Exercise generally had a positive effect on rate of cognitive decline in AD. A meta-analysis found that exercise interventions have a positive effect on global cognitive function, 0.75 (95% CI = 0.32–1.17). ... The most prevalent subtype of dementia is Alzheimer’s disease (AD), accounting for up to 65.0% of all dementia cases ... Cognitive decline in AD is attributable at least in part to the buildup of amyloid and tau proteins, which promote neuronal dysfunction and death (Hardy and Selkoe, 2002; Karran et al., 2011). Evidence in transgenic mouse models of AD, in which the mice have artificially elevated amyloid load, suggests that exercise programs are able to improve cognitive function (Adlard et al., 2005; Nichol et al., 2007). Adlard and colleagues also determined that the improvement in cognitive performance occurred in conjunction with a reduced amyloid load. Research that includes direct indices of change in such biomarkers will help to determine the mechanisms by which exercise may act on cognition in AD.»
* ↑ Am J Occup Ther, 68, 1, 01-01-2014, pàg. 50–56. DOI: 10.5014/ajot.2014.009035. PMC: 5360200. PMID: 24367955. «Alzheimer’s disease (AD) is a progressive neurological disorder characterized by loss in cognitive function, abnormal behavior, and decreased ability to perform basic activities of daily living [(ADLs)] ... All studies included people with AD who completed an exercise program consisting of aerobic, strength, or balance training or any combination of the three. The length of the exercise programs varied from 12 weeks to 12 months. ... Six studies involving 446 participants tested the effect of exercise on ADL performance ... exercise had a large and significant effect on ADL performance (z = 4.07, p < .0001; average effect size = 0.80). ... These positive effects were apparent with programs ranging in length from 12 wk (Santana-Sosa et al., 2008; Teri et al., 2003) and intermediate length of 16 wk (Roach et al., 2011; Vreugdenhil et al., 2012) to 6 mo (Venturelli et al., 2011) and 12 mo (Rolland et al., 2007). Furthermore, the positive effects of a 3-mo intervention lasted 24 mo (Teri et al., 2003). ... No adverse effects of exercise on ADL performance were noted. ... The study with the largest effect size implemented a walking and aerobic program of only 30 min four times a week (Venturelli et al., 2011).»
* ↑ J Parkinsons Dis, 4, 1, 2014, pàg. 1–13. DOI: 10.3233/JPD-130335. PMID: 24473219 [Consulta: free].
* 1 2 Rev Neurosci, 24, 2, 2013, pàg. 139–152. DOI: 10.1515/revneuro-2012-0087. PMID: 23492553.
* ↑ Mov. Disord., 28, 11, 01-09-2013, pàg. 1587–1596. DOI: 10.1002/mds.25658. PMID: 24132847.
* ↑ Cochrane Database Syst Rev, 9, 9, 01-09-2013, pàg. CD002817. DOI: 10.1002/14651858.CD002817.pub4. PMC: 7120224. PMID: 24018704.
* ↑ BMC Public Health, 14, 01-05-2014, pàg. 510. DOI: 10.1186/1471-2458-14-510. PMC: 4064273. PMID: 24885250. «Longitudinal observational studies show an association between higher levels of physical activity and a reduced risk of cognitive decline and dementia. A case can be made for a causal interpretation. Future research should use objective measures of physical activity, adjust for the full range of confounders and have adequate follow-up length. Ideally, randomised controlled trials will be conducted. ... On the whole the results do, however, lend support to the notion of a causal relationship between physical activity, cognitive decline and dementia, according to the established criteria for causal inference.»
* ↑ Front. Psychiatry, 6, 01-02-2016, pàg. 175. DOI: 10.3389/fpsyt.2015.00175. PMC: 4745113. PMID: 26903885 [Consulta: free]. «There is accelerating evidence that physical exercise is a useful treatment for preventing and reducing drug addiction ... In some individuals, exercise has its own rewarding effects, and a behavioral economic interaction may occur, such that physical and social rewards of exercise can substitute for the rewarding effects of drug abuse. ... The value of this form of treatment for drug addiction in laboratory animals and humans is that exercise, if it can substitute for the rewarding effects of drugs, could be self-maintained over an extended period of time. Work to date in [laboratory animals and humans] regarding exercise as a treatment for drug addiction supports this hypothesis. ... However, a RTC study was recently reported by Rawson et al. (226), whereby they used 8 weeks of exercise as a post-residential treatment for METH addiction, showed a significant reduction in use (confirmed by urine screens) in participants who had been using meth 18 days or less a month. ... Animal and human research on physical exercise as a treatment for stimulant addiction indicates that this is one of the most promising treatments on the horizon. [emphasis added]»
* ↑ Neurosci Biobehav Rev, 37, 8, 01-09-2013, pàg. 1622–1644. DOI: 10.1016/j.neubiorev.2013.06.011. PMC: 3788047. PMID: 23806439.
* ↑ Neuropharmacology, 61, 7, 01-12-2011, pàg. 1109–1122. DOI: 10.1016/j.neuropharm.2011.03.010. PMC: 3139704. PMID: 21459101. «Similar to environmental enrichment, studies have found that exercise reduces self-administration and relapse to drugs of abuse (Cosgrove et al., 2002; Zlebnik et al., 2010). There is also some evidence that these preclinical findings translate to human populations, as exercise reduces withdrawal symptoms and relapse in abstinent smokers (Daniel et al., 2006; Prochaska et al., 2008), and one drug recovery program has seen success in participants that train for and compete in a marathon as part of the program (Butler, 2005). ... In humans, the role of dopamine signaling in incentive-sensitization processes has recently been highlighted by the observation of a dopamine dysregulation syndrome in some patients taking dopaminergic drugs. This syndrome is characterized by a medication-induced increase in (or compulsive) engagement in non-drug rewards such as gambling, shopping, or sex (Evans et al., 2006; Aiken, 2007; Lader, 2008).»
* ↑ Am J Drug Alcohol Abuse, 41, 1, 2015, pàg. 7–15. DOI: 10.3109/00952990.2014.976708. PMC: 4831948. PMID: 25397661. «The limited research conducted suggests that exercise may be an effective adjunctive treatment for SUDs. In contrast to the scarce intervention trials to date, a relative abundance of literature on the theoretical and practical reasons supporting the investigation of this topic has been published. ... numerous theoretical and practical reasons support exercise-based treatments for SUDs, including psychological, behavioral, neurobiological, nearly universal safety profile, and overall positive health effects.»
* ↑ Front. Neuroendocrinol., 40, 01-07-2015, pàg. 24–41. DOI: 10.1016/j.yfrne.2015.07.001. PMC: 4712120. PMID: 26182835. «Collectively, these findings demonstrate that exercise may serve as a substitute or competition for drug abuse by changing ΔFosB or cFos immunoreactivity in the reward system to protect against later or previous drug use. ... As briefly reviewed above, a large number of human and rodent studies clearly show that there are sex differences in drug addiction and exercise. The sex differences are also found in the effectiveness of exercise on drug addiction prevention and treatment, as well as underlying neurobiological mechanisms. The postulate that exercise serves as an ideal intervention for drug addiction has been widely recognized and used in human and animal rehabilitation. ... In particular, more studies on the neurobiological mechanism of exercise and its roles in preventing and treating drug addiction are needed.»
* ↑ Front. Oncol., 5, 01-04-2015, pàg. 85. DOI: 10.3389/fonc.2015.00085. PMC: 4389372. PMID: 25905043 [Consulta: free].