PEOPLE HAVE SHOWN considerable creativity in discovering

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1 358 ORIGINAL ARTICLE Exercisers Achieve Greter Acute Exercise-Induced Mood Enhncement Thn Nonexercisers Mrtin D. Hoffmn, MD, Debi Rufi Hoffmn, MA ABSTRACT. Hoffmn MD, Hoffmn DR. Exercisers chieve greter cute exercise-induced mood enhncement thn nonexercisers. Arch Phys Med Rehbil 28;89: Objective: To determine whether single session of exercise of pproprite intensity nd durtion for erobic conditioning hs different cute effect on mood for nonexercisers thn regulr exercisers. Design: Repeted-mesures design. Setting: Reserch lbortory. Prticipnts: Adult nonexercisers, moderte exercisers, nd ultrmrthon runners (8 men, 8 women in ech group). Interventions: Tredmill exercise t self-selected speeds to induce rting of perceived exertion (RPE) of 13 (somewht hrd) for 2 minutes, preceded nd followed by 5 minutes t n RPE of 9 (very light). Min Outcome Mesure: Profile of Mood Sttes before nd 5 minutes fter exercise. Results: Vigor incresed by men stndrd devition of 8 7 points (95% confidence intervl [CI], 5 12) mong the ultrmrthon runners nd 5 4 points (95% CI, 2 9) mong the moderte exercisers, with no improvement mong the nonexercisers. Ftigue decresed by 5 6 points (95% CI, 2 8) for the ultrmrthon runners nd 4 4 points (95% CI, 1 7) for the moderte exercisers, with no improvement mong the nonexercisers. totl mood disturbnce decresed by men of points (95% CI, 12 29) mong the ultrmrthon runners, 16 1 points (95% CI, 7 24) mong the moderte exercisers, nd 9 13 points (95% CI, 1 18) mong the nonexercisers. Conclusions: A single session of moderte erobic exercise improves vigor nd decreses ftigue mong regulr exercisers but cuses no chnge in these scores for nonexercisers. Although totl mood disturbnce improves postexercise in exercisers nd nonexercisers, regulr exercisers hve pproximtely twice the effect s nonexercisers. This limited postexercise mood improvement mong nonexercisers my be n importnt deterrent for persistence with n exercise progrm. Key Words: Affect; Ftigue; Physicl fitness; Rehbilittion; Stress, psychologicl. 28 by the Americn Congress of Rehbilittion Medicine nd the Americn Acdemy of Physicl Medicine nd Rehbilittion From the Deprtment of Physicl Medicine & Rehbilittion, Deprtment of Veterns Affirs, Northern Cliforni Helth Cre System, Scrmento, CA (MD Hoffmn); University of Cliforni-Dvis Medicl Center, Scrmento, CA (MD Hoffmn); nd Cliforni School of Professionl Psychology, Allint Interntionl University, Scrmento, CA (DR Hoffmn). No commercil prty hving direct finncil interest in the results of the reserch supporting this rticle hs or will confer benefit upon the uthors or upon ny orgniztion with which the uthors re ssocited. Reprint requests to Mrtin D. Hoffmn, MD, Dept of Physicl Medicine & Rehbilittion (117), Scrmento VA Medicl Center, 1535 Hospitl Wy, Mther, CA , e-mil: mrtin.hoffmn@v.gov /8/ $34./ doi:1.116/j.pmr PEOPLE HAVE SHOWN considerble cretivity in discovering wys to void exercise. In fct, most U.S. dults do not regulrly prticipte in physicl ctivities t the minimum recommended levels ssocited with helth benefits. 1 An importnt contributing fctor to this problem is tht pproximtely hlf of the people who begin n exercise progrm will fil to continue beyond 6 months. 2 Given the extent of disese risk relted to physicl inctivity nd the high ssocited societl cost, 3 it is criticlly importnt to improve our understnding of mesures tht cn enhnce prticiption in regulr physicl ctivity. In ddition to importnt physicl helth benefits resulting from regulr exercise, 4-7 there is good evidence tht psychologic benefits cn lso be ttined from exercise conditioning Furthermore, mood cn be improved cutely fter even single session of exercise However, it is not cler if cute mood improvements occur for middle-ged nonexercisers fter performing session of exercise of pproprite intensity nd durtion for developing crdiorespirtory fitness. This is becuse previous work hs primrily focused on college-ged subjects, for whom the discrepncy in fitness between exercisers nd nonexercisers my be less pprent thn for older dults. An importnt fctor contributing to the difficulty of continuing n exercise progrm could be tht nonexercisers hve blunted improvement in mood fter exercise. To explore this, we mesured mood stte before nd fter single bout of exercise of suitble intensity nd durtion for crdiorespirtory conditioning, nd we compred the responses mong middleged dult nonexercisers nd 2 groups of regulr exercisers. METHODS Three groups of dult subjects (nonexercisers, regulr moderte exercisers, ultrmrthon runners) prticipted in the study, with 16 subjects (8 men, 8 women) in ech group. Smple size determintion bsed on preliminry dt from our lbortory indicted tht group sizes of 16 would be dequte reltive to the min study vribles. All prticipnts were educted beyond high school nd were free of known crdiovsculr, pulmonry, nd metbolic diseses. Exclusion criteri included known pregnncy, the use of tobcco or nicotine-contining products, use of mood-ltering medictions or drugs, nd musculoskeletl disorders interfering with exercise. All subjects were required to hve previously used tredmill. They were ll dvised to not exercise on the dy of the study before testing, to not consume food or cffeine during the 2 hours before testing, nd to not tke pin or nti-inflmmtory mediction during the 6 hours before testing. Inclusion in the group of nonexercisers required people to hve engged in 5 or fewer erobic exercise sessions month of no more thn 25 minutes session during the 6 months preceding the study. Criteri for the regulr moderte exerciser group included performing erobic exercise for 3 to 6 minutes, 3 to 6 times week, most weeks during the previous 6 months. Inclusion in the group of ultrmrthon runners required completion of t lest 2 competitive running rces of distnce of t lest 5km in the preceding 24 months. Ultr- Arch Phys Med Rehbil Vol 89, Februry 28

2 ACUTE MOOD CHANGES FROM EXERCISE, Hoffmn 359 Tble 1: Subjects Selected Chrcteristics Chrcteristics Nonexercisers Moderte Exercisers Ultrmrthon Runners Age (y) Body mss index (kg/m 2 ) * * IPAQ leisure time (MET min wk 1 ) * * IPAQ totl (MET min wk 1 ) * * NOTE. Vlues re men SD. Sttisticl differences t P.1 level present between vlues identified with the sme superscript (*, ). Abbrevition: MET, metbolic equivlent. mrthon runners were lso required to hve engged in erobic exercise for minimum durtion of 45 minutes during ech exercise session, t lest 4 dys week for most weeks during the preceding 12 months. Nonexercisers nd regulr moderte exercisers were recruited through flyers nd word of mouth in the medicl center where the reserch ws conducted, the ffilited universities, nd the surrounding communities nd businesses. Ultrmrthon runners were recruited through mss emiling to locl ultrmrthon runners nd through personl contct. Ech prticipnt ws provided $2 gift certificte to locl grocery store chin fter completion of the study. Study prticipnts cme to the lbortory on 1 occsion. Ech completed the informed consent process nd signed consent form pproved by the institutionl review bord, nd ech completed the long form, lst 7 dys, self-dministered version of the Interntionl Physicl Activity Questionnire (IPAQ). 13 The IPAQ is vlidted self-reported mesure for ssessing physicl ctivity, 14 which ws used to chrcterize subject groups. Subjects were lso cquinted with the opertion of the motorized tredmill nd were informed of the study protocol, but they were not provided detils bout the hypotheses being tested. Height nd body mss were mesured. Subjects then rested in chir for 5 minutes, completed the Profile of Mood Sttes (POMS), nd rested nother 5 minutes, fter which they were instructed to get on the tredmill. They were told to djust the tredmill speed so tht the intensity resulted in rting of perceived exertion (RPE) of 9 (very light) on the Borg 6-2 scle 15 for 5 minutes, followed by n RPE of 13 (somewht hrd) for 2 minutes, nd then bck to n RPE of 9 for the lst 5 minutes. This exercise protocol ws chosen becuse the durtion nd intensity fll within the rnge generlly dvised for crdiorespirtory conditioning in helthy dults. 4-7 After completion of the exercise, subjects were instructed to rest in the chir, nd fter 5 minutes they completed the POMS gin. Tredmill grde ws mesured nd remined t 2% throughout exercise. A slight incline ws used becuse it produces energy costs more consistent with on-ground movement, t lest t running speeds. 16 Tredmill speed ws recorded t the end of ech 5 minutes of exercise. The POMS is 65-item self-report inventory, requiring only few minutes to complete, 17 tht hs been used extensively to ssess the cute effects of exercise on mood. 8,9,11,12 The POMS mesures 6 dimensions of mood on 5-point continuum. A totl mood disturbnce index is derived by subtrcting the vigor-ctivity score from the sum of the other 5 mesures of ffect (tension-nxiety, depression-dejection, nger-hostility, ftigue-inerti, confusion-bewilderment). With ech dministrtion of the POMS, ech subject ws provided instructions to record his/her mood bsed on how he/she ws feeling t the present time. The sme investigtor ws present during ech test but voided interction with subjects once the first rest period begn, t which time instructions were provided through n udio recording. Ech time the intensity ws to chnge, the instructions indicted tht subjects could djust the speed throughout the exercise period s necessry to mintin the desired intensity. Subjects were not llowed to use wtches or music throughout the study, nd tredmill speed, grde, nd time displys were covered to prohibit viewing by subjects. The room where the exercise ws performed ws well lighted but hd no windows nd miniml distrctions. An RPE chrt ws mounted on the wll directly in front of the tredmill. Men stndrd devition (SD) room temperture ws C. The min dependent vribles in this study were the 6 dimensions of mood nd totl mood disturbnce s mesured with the POMS. Ech of these vribles, s well s tredmill speed, were nlyzed with 2-wy (group by time) repetedmesures nlyses of vrince (ANOVAs) nd Bonferroni post-tests. Subject chrcteristics were compred with 1-wy ANOVA nd the Tukey-Krmer post-test. When n nticipted sttisticl significnce ws not ttined, effect size (ES) ws determined by dividing the between-group difference in mens by the pooled SD. As proposed by Cohen, 18 ES ws considered smll for ES less thn or equl to.2, moderte for ES less thn or equl to.5 nd lrge for ES greter thn.8. A probbility vlue of less thn.5 ws ccepted s significnt. RESULTS Selected subject chrcteristics re shown in tble 1. Ages rnged from 28 to 59 yers nd were comprble mong groups. As expected, body mss index ws lower (P.1) mong the moderte exercisers nd ultrmrthon runners compred with the nonexercisers. Physicl ctivity levels (leisure time component nd totl) during the 7 dys preceding the study, s determined by the IPAQ, were higher (P.1) mong the ultrmrthon runners compred with the nonexercisers nd moderte exercisers. Leisure time nd totl physicl ctivity levels were not sttisticlly different between nonexercisers nd moderte exercisers but hd ESs tht were lrge (ES 2.3) nd moderte to lrge (ES.7), respectively. The subscores of the POMS re shown in figure 1. Tension showed smll but significnt decrese of 3 points in ll groups (95% confidence intervl [CI], 1 5 for ultrmrthon runners nd moderte exercisers; 1 6 for nonexercisers). The nonexercisers showed decrese of 3 points in depression (95% CI, 1 5) nd decrese of 2 points in nger (95% CI,.3 3), wheres the ultrmrthon runners nd moderte exercisers showed smll decreses in confusion of 2 points (95% CI,.4 3 for ultrmrthon runners;.2 3 for moderte exercisers). Group-by-time interctions were not significnt for tension, depression, nger, nd confusion. More evident were the chnges in vigor nd ftigue. Vigor incresed by men SD of 8 7 points (95% CI, 5 12) mong the ultrmrthon runners nd 5 4 points (95% CI, 2 9) mong the moderte exercisers, wheres ftigue de- Arch Phys Med Rehbil Vol 89, Februry 28

3 36 ACUTE MOOD CHANGES FROM EXERCISE, Hoffmn 3 Tension 3 Depression 3 Anger * 3 Vigor 3 Ftigue 3 Confusion * * Fig 1. Six dimensions of mood from the POMS for the nonexercisers (Œ), moderte exercisers ( ), nd ultrmrthon runners ( ). Significnt pre-exercise to postexercise differences re indicted with dshed lines nd symbols ( * P<.5, P<.1, P<.1). Error brs represent 1 SD nd for clrity re displyed in only 1 direction for 2 groups. cresed by men of 5 6 points (95% CI, 2 8) for the ultrmrthon runners nd 4 4 points (95% CI, 1 7) mong the moderte exercisers. Significnt group-by-time interctions (P.6, P.8, respectively) indicte tht there were differences mong groups in the effects of exercise on vigor nd ftigue. totl mood disturbnce ws decresed by men SD of points (95% CI, 12 29) mong the ultrmrthon runners, 16 1 (95% CI, 7 24) mong the moderte exercisers, nd 9 13 points (95% CI, 1 18) mong the nonexercisers (fig 2). A nerly significnt group-by-time interction (P.8) is suggestive of trend towrd less of n effect mong the nonexercisers thn the other groups. Tredmill speeds re displyed in figure 3. There were no differences in speeds between the ultrmrthon runners nd moderte exercisers. However, tredmill speeds for the nonexercisers were slower cross ll time points compred with the ultrmrthon runners nd for ll time points t the higher RPE compred with the moderte exercisers. DISCUSSION This study found tht single session of exercise of pproprite intensity nd durtion for erobic fitness trining resulted in n increse in vigor nd decrese in ftigue mong dult ultrmrthon runners nd regulr moderte exercisers. In contrst, dult nonexercisers showed no improvement in these scores, nd the effect ws sttisticlly different for this group compred with the exercisers. Although totl mood disturbnce improved in ll 3 groups fter exercise, the 2 groups of exercisers showed pproximtely double the effect of the nonexercisers. These findings re likely importnt determinnts for the overwhelming difficulty people hve with persistence t n exercise progrm. Regulr exercisers probbly recognize tht they will feel more energized fter n exercise session, mking it esier for them to initite ech workout. Novice exercisers would pper to be less likely to hve s strong of motivting force. The modest improvement in totl mood scores mong the nonexercisers resulted from sttisticlly significnt improvements in tension, depression, nd nger. For ech vrible, the effect ws smll nd not sttisticlly different from wht ws observed mong the exercisers. Furthermore, the effect did not pper to be due to n rtificil elevtion of pre-exercise vlues due to the nticiption of n unfmilir experience (ie, the exercise), becuse pre-exercise vlues were low, within the normtive rnge 19 nd comprble mong groups. Quiet rest lone is known to induce cute improvements in nxiety of similr mgnitude to erobic exercise. 11,2 As such, the smll Arch Phys Med Rehbil Vol 89, Februry 28

4 ACUTE MOOD CHANGES FROM EXERCISE, Hoffmn Totl Mood Disturbnce Fig 2. Totl mood disturbnce for the nonexercisers (Œ), moderte exercisers ( ), nd ultrmrthon runners ( ). Significnt preexercise to postexercise differences re indicted with dshed lines nd symbols ( * P<.5, P<.1). Error brs represent 1 SD nd for clrity re displyed in only 1 direction for 2 groups. * improvements in tension, depression, nd nger tht nonclinicl, sedentry people receive from session of erobic exercise my serve s little incentive for exercise over performing other ctivities tht yield no benefits to crdiovsculr helth. Few previous studies hve compred cute exercise-induced mood ltertions between regulr exercisers nd nonexercisers. From those studies in which such comprison ws mde, it is difficult to rech conclusion other thn tht there seems to be greter reduction in nxiety mong regulr exercisers thn nonexercisers. Furthermore, in ech of the studies tht hve compred cute exercise-induced mood chnges between regulr exercisers nd nonexercisers, subjects were young dults or students. Results from popultions of young dults cnnot necessrily be generlized to middle-ged popultion, becuse young dults re likely to be more fit s result of their youth nd re engged in different lifestyle thn the blnce of the dult popultion. The ge rnge of subjects in the present study ws 28 to 59 yers. With men ge over 4 yers for ech group, prticipnts in this study represent wide ge rnge strting well beyond the typicl college yers, in which mny people re more likely to mintin fitness. Hence, this study is more representtive of those in middle ge thn the erlier studies tht involved young dults nd students. It ws nticipted tht, if the cute mood effects from exercise were different between regulr exercisers nd nonexercisers, the difference would be most evident mong groups of very different physicl ctivity levels. Ultrmrthon runners were chosen s 1 of the groups of regulr exercisers in this study becuse they hve much greter physicl ctivity level thn nonexercisers (see tble 1). However, moderte exercisers showed mood chnges comprble with those of ultrmrthon runners. Previous work hs shown greter tendency towrd exercise dependence for runners prticipting in longer-distnce events. 29 Whether exercise dependence is relted to the cute mood effects from exercise is not cler. Nonetheless, the results of this study suggest tht regulr moderte exercisers hve n importnt cute mood enhncement from exercise tht probbly hs fvorble impct on their continution of regulr exercise progrm. Mny regulr exercisers prefer different exercise conditions thn were imposed by this study. For instnce, wlking or running outdoors over vrying terrin nd for longer durtion would likely hve been preferred by some of the exercisers. As such, it would be nticipted tht under more preferble exercise circumstnces, the mood improvements for the exercisers might be even greter thn were observed here. The mechnism ccounting for the group differences in cute mood chnge from exercise cnnot be elucidted from this study; however, possible explntions cn be considered. Differences in exercise worklods between the regulr exercisers nd nonexercisers my hve plyed role. An RPE of 13 hs been shown to be close to the lctte threshold for trined s well s for untrined men nd women. 3 However, the reltionship between RPE nd percentge of mximl oxygen uptke (V O2 mx) is ffected by fitness level in such wy tht, t given RPE, the percentge of V O2 mx is higher for those who re trined. 3 Therefore, in the present study, it is likely tht ultrmrthon runners nd moderte exercisers were exercising t higher bsolute worklod nd higher percentge of V O2 mx thn the nonexercisers. This my, t lest prtilly, ccount for the greter mood effect tht ws observed in the exercisers, becuse mny of the theories of the underlying mechnisms for exercise-induced mood chnge 8,9 re bsed on physiologic responses tht re directly relted to bsolute or reltive exercise intensity. Another possible explntion for the present findings my relte to individul vritions in the cute mood response to exercise. Elevtion in mood nd reduced tension fter exercise Tredmill Speed (km/h) 12 1 b b b b 8 6 b b b b 4 2 Ultrmrthoners Moderte Exercisers Nonexercisers Time (min) Fig 3. Tredmill speeds t the end of ech 5-minute period for the 3 groups. Significnt differences between groups re indicted by the sme letter (, b). Error brs represent 1 SD nd for clrity re displyed in only 1 direction for 2 groups. Arch Phys Med Rehbil Vol 89, Februry 28

5 362 ACUTE MOOD CHANGES FROM EXERCISE, Hoffmn re recognized to be powerful motivtors for continuing running progrm. 31,32 We would nticipte tht nonexercisers who strt nd dhere to regulr exercise progrm will eventully begin to experience mood enhncement similr to tht observed mong the exercisers in this study. However, it is conceivble tht some people my not cquire such benefits even fter consistent prticiption in n exercise trining progrm. For those people, the doption of sedentry lifestyle could be mnifesttion of blunted mood response to exercise. Given the growing evidence for genetic links to certin cute physiologic responses to exercise, dpttions to exercise trining, nd exercise intolernce, 33 further efforts t investigting genetic bsis for exercise dherence seem importnt. Future reserch should lso include longitudinl exercise trining studies tht explore the durtion of prticiption in regulr exercise progrm tht might be required for cute postexercise mood enhncement to become evident. Study Limittions Some limittions to the study re cknowledged. One limittion is tht objective physiologic mesurements to determine exercise intensity were not mde in this study. We specificlly chose to void hert rte nd oxygen uptke mesurements during the exercise to limit intrusions on subjects tht might ffect mood. As result, we cnnot define the exercise intensities beyond n estimtion of wht is typicl for n RPE of 13. However, our pproch ws justified in tht perception of effort is the typicl mnner in which people estblish exercise intensity. An RPE of 13 (somewht hrd) flls in the middle of the rnge of recommended exercise intensities of pproximtely 5% to 85% of V O2 mx or 6% to 9% of mximl hert rte. 34 The timing of the postexercise POMS mesurement ws determined bsed on previous studies showing exercise-induced mood enhncement t bout 5 minutes fter exercise. 2,22,24,35-37 It could be considered limittion by some tht the POMS ws mesured t only 5 minutes postexercise nd not repeted t lter time. However, hd we performed POMS ssessment t lter time point, there would then be potentilly confounding issue of wht subjects hd done during the intervl between completions of the POMS, becuse it is know tht relxtion nd quiet rest lone cn lter mood. 11,2 Another concern with performing only 1 postexercise mood ssessment is tht the effect could be missed becuse the gretest chnge hd lredy dissipted or hd not yet occurred t the time of ssessment. It is lso conceivble tht mood chnges could follow different time course depending on fitness level when exercise intensity is estblished by RPE. One study hs shown tht improvements in stte nxiety were found to be delyed beyond 5 minutes postexercise when the exercise ws t intensities of 7% to 8% of V O2 mx, wheres the effect ws more immedite fter moderte exercise intensities. 2,35 Although the exercise intensity s percentge of V O2 mx likely differed mong the groups in this study, n RPE of 13 typiclly corresponds to V O2 mx of less thn 7%, 34 nd it would be expected tht unfit subjects would be t lower percentge of V O2 mx for given RPE thn fit subjects. 3 As such, it is unlikely tht the nonexercisers were t high enough intensity for delyed response to hve been n issue in the ssessment of tension-nxiety. Furthermore, the tensionnxiety scores were low t bseline mong ll groups, leving little room for further improvement beyond wht ws observed. CONCLUSIONS Although previous work hs shown tht erobic exercise generlly results in cute mood improvements, very little ttention hs been directed t determining whether this effect is similrly present mong regulr exercisers nd nonexercisers. Furthermore, there hs been no comprison of regulr exercisers nd nonexercisers who re middle-ged using exercise intensities nd durtions within the rnge tht is recommended for enhncing helth nd fitness. The present study helps clrify tht dult nonexercisers hve sttisticlly significnt improvements in totl mood disturbnce tht my hve some clinicl relevnce. However, the mood improvement mong nonexercisers is exceeded by the response mong regulr exercisers. The lck of n increse in vigor nd decrese in ftigue mong dult nonexercisers my contribute to the difficulties experienced by these people in mintining regulr exercise progrm. Such informtion should be shred with those inititing n exercise progrm so tht they my be more likely to persist through the initil phses of the progrm. References 1. Centers for Disese Control nd Prevention (CDC). Adult prticiption in recommended levels of physicl ctivity United Sttes, 21 nd 23. MMWR Morb Mortl Wkly Rep 25;54: Robinson JI, Rogers MA. Adherence to exercise progrmmes. Recommendtions. Sports Med 1994;17: Anderson LH, Mrtinson BC, Crin AL, et l. Helth cre chrges ssocited with physicl inctivity, overweight, nd obesity. Prev Chronic Dis 25;2(4):A9. 4. Americn College of Obstetricins nd Gynecologists. Exercise during pregnncy nd the postprtum period. Clin Obstet Gynecol 23;46: Hskell WL, Lee IM, Pte RR, et l. Physicl ctivity nd public helth: updted recommendtion for dults from the Americn College of Sports Medicine nd the Americn Hert Assocition. Med Sci Sports Exerc 27;39: Pte RR, Prtt M, Blir SN, et l. Physicl ctivity nd public helth. 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