Quantification of Recruit Training Demands and Subjective Wellbeing during Basic Military Training

This is a sel -a chi ed e sion o an o iginal a icle. This e sion may di e om he o iginal in pagina ion and ypog aphic de ails. Au ho (s): Ti le: Yea : Ve sion: Copy igh : Righ s: Righ s u l: Please ci e he o iginal e sion: CC BY 4.0 h ps://c ea i ecommons.o g/licenses/by/4.0/ Quan i ica ion o Rec ui T aining Demands and Subjec i e Wellbeing du ing Basic Mili a y T aining © he Au ho s, 2022. Published e sion Bulme , Sean; D ain, Jace R.; Tai , Jamie L.; Co igan, Sean L.; Gas in, Paul B.; Aisbe , B ad; Ran alainen, Timo; Main, Luana C. Bulme , S., D ain, J. R., Tai , J. L., Co igan, S. L., Gas in, P. B., Aisbe , B., Ran alainen, T., & Main, L. C. (2022). Quan i ica ion o Rec ui T aining Demands and Subjec i e Wellbeing du ing Basic Mili a y T aining. In e na ional Jou nal o En i onmen al Resea ch and Public Heal h, 19(12), A icle 7360. h ps://doi.o g/10.3390/ije ph19127360 2022 Ci a ion: Bulme , S.; D ain, J.R.; Tai , J.L.; Co igan, S.L.; Gas in, P.B.; Aisbe , B.; Ran alainen, T.; Main, L.C. Quan i ica ion o Rec ui T aining Demands and Subjec i e Wellbeing du ing Basic Mili a y T aining. In . J. En i on. Res. Public Heal h 2022,19, 7360. h ps://doi.o g/10.3390/ ije ph19127360 Academic Edi o : Paul B. Tchounwou Recei ed: 9 May 2022 Accep ed: 8 June 2022 Published: 15 June 2022 Publishe ’s No e: MDPI s ays neu al wi h ega d o ju isdic ional claims in published maps and ins i u ional a il- ia ions. Copy igh : © 2022 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion (CC BY) license (h ps:// c ea i ecommons.o g/licenses/by/ 4.0/). In e na ional Jou nal o En i onmen al Resea ch and Public Heal h A icle Quan i ica ion o Rec ui T aining Demands and Subjec i e Wellbeing du ing Basic Mili a y T aining Sean Bulme 1, Jace R. D ain 2, Jamie L. Tai 3, Sean L. Co igan 1, Paul B. Gas in 4, B ad Aisbe 3, Timo Ran alainen 5and Luana C. Main 3,* 1Cen e o Spo Resea ch, School o Exe cise and Nu i ion Sciences, Deakin Uni e si y, Geelong 3220, Aus alia; [email p o ec ed] (S.B.); [email p o ec ed] (S.L.C.) 2De ence Science and Technology G oup, Fishe mans Bend 3207, Aus alia; [email p o ec ed].au 3Ins i u e o Physical Ac i i y and Nu i ion (IPAN), School o Exe cise and Nu i ion Sciences, Deakin Uni e si y, Geelong 3220, Aus alia; [email p o ec ed] (J.L.T.); [email p o ec ed] (B.A.) 4La T obe Spo and Exe cise Medicine Resea ch Cen e, School o Allied Heal h, Human Se ices and Spo , La T obe Uni e si y, Bundoo a 3083, Aus alia; p.gas in@la obe.edu.au 5Ge on ology Resea ch Cen e and Facul y o Spo and Heal h Sciences, Uni e si y o Jy äskylä, 40014 Jy äskylä, Finland; [email p o ec ed] *Co espondence: [email p o ec ed]; Tel.: +61-39244-5030 Abs ac : Pu pose: Assess and desc ibe he physical demands and changes in subjec i e wellbeing o ec ui s comple ing he 12 week Aus alian A my Basic Mili a y T aining (BMT) cou se. Me hods: Thi y- i e ec ui s (24.8 ± 6.8 y; 177.4 ± 10.1 cm, 75.6 ± 14.7 kg) consen ed o daily ac i i y moni o ing and weekly measu es o subjec i e wellbeing (Mul i-componen T aining Dis ess Scale, MTDS). The physical demands o aining we e assessed ia w is wo n ac i i y moni o s (Ac ig aph GT9X accele ome e ). Physical i ness changes we e assessed by push-ups, si -ups and mul i-s age shu le un in weeks 2 and 8. Resul s: All objec i e and subjec i e measu es signi ican ly changed (p< 0.05) ac oss he 12 week BMT cou se. In pa allel, he e was a signi ican imp o emen in measu es o physical i ness om weeks 2 o 8 (p< 0.001). The g ea es dis u bance o subjec i e wellbeing occu ed du ing week 10, which was a pe iod o ield aining. Weeks 6 and 12 p o ided oppo uni ies o eco e y as e lec ed by imp o ed wellbeing. Conclusions: The physical demands o aining a ied ac oss he Aus alian A my 12 week BMT cou se and e lec ed he in ended pe iodiza ion o wo kload and eco e y. Physical i ness imp o ed om week 2 o 8, indica ing a posi i e aining esponse o BMT. Consis en wi h indings in spo , wellbeing measu es we e sensi i e o luc ua ions in aining s ess and appea o ha e u ili y o indi idual managemen o pe sonnel in he mili a y aining en i onmen . Keywo ds: soldie ; a my; sel - epo ; moni o ing; ec ui ; allos a ic load 1. In oduc ion Basic Mili a y T aining (BMT) p o ides ec ui s wi h ounda ional aining, p epa ing hem o he igo s o mili a y se ice. Du ing BMT, ec ui s a e exposed o a a ie y o physical and cogni i e demands, including a newly egimen ed li es yle, new social and en i onmen al s esso s, and he cons an p essu e o ins uc o and pee assessmen [ 1 – 3 ]. Rec ui s mus mee a ange o mili a y compe encies and s anda ds o g adua e om BMT and p og ess o ade-speci ic aining (e.g., in an y, logis ics, a mo ed). The de elopmen o mili a y- ele an physical capaci y is he e o e undamen al o many o hese aining ou comes. Howe e , high physical aining olumes, insu icien eco e y oppo uni ies, and inc eased s ess du ing mili a y aining ha e been linked o a numbe o maladap i e ou comes, such as musculoskele al inju y, illness and aining a i ion [ 4 ]. These nega i e ou comes inc ease aining cos s, bu den he heal hca e sys em, inc ease u u e inju y isk, and can impai ca ee p og ession [ 5 ]. Maladap a ion o a aining s imulus can In . J. En i on. Res. Public Heal h 2022,19, 7360. h ps://doi.o g/10.3390/ije ph19127360 h ps://www.mdpi.com/jou nal/ije ph In . J. En i on. Res. Public Heal h 2022,19, 7360 2 o 10 be caused by combina ions o a sudden inc ease in aining load, high o al aining load, inadequa e eco e y, aining mono ony o en i onmen al and li es yle s esso s [ 6 ]. A oiding maladap a ion and achie ing ime-e icien physical pe o mance gains wi h he lowes possible inju y a e is he e o e essen ial o a success ul, sus ainable mili a y [7]. T adi ionally, mili a y physical aining p og ams ha e a o ed ca dio espi a o y and muscula endu ance aining [ 7 , 8 ]. S eady-s a e unning, long-dis ance ma ching, and ci cui aining ha e made up a subs an ial po ion o he p esc ibed wo kload [ 2 , 8 , 9 ]. In compa ison, he de elopmen o muscula s eng h, and he p o ision o delibe a e eco e y pe iods ha e been a lesse ocus [ 8 , 9 ]. This combina ion o mode a e o high olume aining and inadequa e eco e y has been associa ed wi h symp oms o maladap a ion and inc eased inju y incidence [ 7 ]. Con empo a y mili a y aining ecommenda ions ha e subsequen ly speci ied ha physical aining (PT) p og ams include ocused s eng h aining [ 9 ] wi hin a pe iodised p og am ha p o ides p og essi e o e load coupled wi h adequa e eco e y [ 7 ]. In 2015, he Aus alian A my adop ed a mo e con empo a y PT p og am ha inco po a ed muscula s eng h and high-in ensi y in e al aining, o be e align wi h occupa ional demands and mi iga e he isk o p e en able musculoskele al inju ies. Fo p ac icali y, his PT p og am is implemen ed in a g oup aining o ma , wi h some oppo uni y o indi idualiza ion o help ensu e equi alen ela i e in ensi y ac oss he g oup. Howe e , i is unlikely ha he g oup-deli e ed aining s imuli will be op imal o all ec ui s, gi en a iances in i ness and aining his o y [ 10 ]. Mo eo e , g oup-le el aining p esc ip ion wi hou s a egies o moni o indi idual ec ui s’ aining s ain could lead o sub-op imal aining adap a ions, unsus ainable loads o ad e se e en s (i.e., inju y). While PT is an ob ious sou ce o aining demands du ing BMT, om a scheduling pe spec i e, PT lessons ep esen <10% o he o al lesson ime in he Aus alian A my BMT p og am [ 9 ], which is simila o o he BMT cou ses [ 2 ]. In addi ion o PT, he e a e a ious mili a y skill and educa ion lessons (e.g., pa olling, o ensi e and de ensi e g ound maneu e s, na iga ion, d ill, ma ching) ha simila ly impose physical and physiological demands. On op o hese physical demands a e psychological and cogni i e challenges, and dis up ed sleep, all collec i ely con ibu ing o high allos a ic loads [ 1 , 11 , 12 ]. Con- sequen ly, gi en p e iously obse ed high a es o musculoskele al inju y and aining a i ion, he e would be measu able bene i s associa ed wi h he implemen a ion o an ongoing moni o ing sys em o he managemen o he aining demands imposed on ec ui s unde aking BMT. Op imiza ion o high loads in a g oup aining en i onmen is a challenge ha BMT sha es wi h eli e eam spo s. In spo o ganiza ions, consis en and ac ionable in o ma ion o load managemen is ou inely ga he ed ia sel - epo moni o ing s a egies ha ack changes in a hle e wellbeing [ 13 ]. These le e age an indi idual’s pe cep ion o hei wellbeing o e ime, o iden i y a hle es a isk o poo aining ou comes o comp omised pe o mance. Subsequen aining modi ica ions and in e en ions p esc ibed based on known ela ionships be ween aining load and s ess esponses can mi iga e he isk o hese nega i e ou comes [ 14 ]. Sel - epo measu es o subjec i e wellbeing a e widely used o hei cos -e ec i eness and o he minimal ime equi ed o adminis e and analyze he esul s, which makes hem p ac ical o la ge o ganiza ions o implemen . These measu es cha ac e ize an indi idual’s subjec i e s a e in dis inc domains such as s ess, dep essed mood s a es and physical ailmen s (e.g., muscle and join so eness/pain) ela ing o physical and men al wellbeing. Scales measu ing changes in mul iple domains a once (i.e., mood, pe cei ed s ess, symp om checklis s and eco e y s a us) p o ide a mo e holis ic pic u e o an indi idual’s pe cep ion o hei wellbeing, when compa ed wi h measu es om a single domain [ 15 ]. Such measu es a e gaining ac ion, as hey p o ide immedia e insigh s in o he mos a ec ed domains and iden i y a eas ha should be p io i ized o in e en ion. To da e, he demands o aining du ing he ecen ly modi ied Aus alian A my BMT p og am and he p og am’s e ec s on wellbeing ha e no been quan i ied. The e o e, he aims o he cu en s udy we e o (1a) assess and desc ibe he physical demands imposed on ec ui s In . J. En i on. Res. Public Heal h 2022,19, 7360 3 o 10 du ing BMT; (1b) quan i y subjec i e wellbeing o ec ui s du ing BMT; and (2) explo e ela ionships be ween he physical demands and subjec i e wellbeing du ing BMT. 2. Me hods 2.1. Pa icipan s Pa icipan s we e Aus alian A my ec ui s commencing he 12-week BMT p og am a he A my Rec ui T aining Cen e, Blamey Ba acks, Kapooka, Aus alia in July 2018. The ec ui s we e om wo pla oons wi hin he same aining company and commenced BMT on he same day. Po en ial pa icipan s we e e bally b ie ed and p o ided a w i en p ojec desc ip ion by an in es iga o in acco dance wi h he p o ocol app o ed by he Depa men o De ence and Ve e ans’ A ai s Human Resea ch E hics Commi ee (p o ocol numbe : 021-17). No uni o med pe sonnel we e p esen o he b ie ing, and i was made clea ha pa icipa ion was olun a y and would ha e no bea ing on cu en o u u e ca ee oppo uni ies. W i en in o med consen o pa icipa e was p o ided by 48 ec ui s, and desc ip i e da a is p o ided in Table 1. All pa icipan s me he Aus alian A my enlis men i ness equi emen s o 45 si -ups wi h ee held, a 7.5 mul i-s age shu le un sco e, and 8 ( emale) o 15 (male) push-ups. Table 1. Desc ip i e da a o pa icipan s. Pa icipan Va iable Value N 48 Age 24.4 ±7.1 Heigh (cm) 176.5 ±9.9 Body Mass (kg) 76.8 ±14.7 2.2. Expe imen al Design and P ocedu es Following he p o ision o consen du ing he i s week o BMT, a baseline physical ac i i y ques ionnai e, he In e na ional Physical Ac i i y Ques ionnai e (IPAQ) Sho Fo m was comple ed wi hin 48 h. The ques ionnai e consis s o ou ques ions (wi h embedded sub-ques ions) ela ing o igo ous, mode a e, and walking physical ac i i y, as well as seden a y beha io pe o med in he pas se en days [ 16 ]. The IPAQ esul s showed ha pe day p io o BMT, ec ui s spen a daily a e age o 4.8 h si ing, 1.7 h walking, 1 h a mode a e in ensi ies, and 0.8 h a igo ous in ensi ies. An h opome ic da a was ga he ed om he A my’s ini ial sc eening o he ec ui s by heal h cen e nu sing s a . Fo he du a ion o BMT, pa icipan s wo e an Ac iG aph GT9x (Ac iG aph, Pensacola, FL, USA) on hei non-dominan w is . Uni s we e se a a collec ion a e o 30 Hz using 60 s epochs. Daily s eps and physical ac i i y coun s we e used o quan i y he physical demands o aining. Ac i i y coun s we e con e ed o a daily es ima ion o ene gy expendi u e (EE) ia he me hod o neu al ne wo k, including absolu e accele a ion alues and ‘ ea u e se 1 0 o w is -independen EE es ima ion, as desc ibed by Mon oye e al. [ 17 ]. The calcula ed METs pe day o each pa icipan we e summed o epo daily MET minu es, wi h he weekly o al ene gy expendi u e being he accumula ion o MET minu es om Monday o Sunday each week. These esul s a e epo ed as weekly ene gy expendi u e (MET minu es) and % weekly o al ime in zones o seden a y, ligh , mode a e, igo ous, as well as mode a e and igo ous physical ac i i y (MVPA) [ 18 ]. A minimum o i e days o da a pe week pe pa icipan was equi ed o inclusion in he physical ac i i y analysis pe week. Due o ha ing less han a ull week o da a a e consen was g an ed, week 1 accele ome e da a we e no included in he analysis. Pa icipan s wo e he Ac iG aphs o he en i e du a ion o he s udy, excep o any pe iods o wa e imme sion (i.e., showe ing o swimming), and o cha ge he uni s. The de ices we e collec ed by esea ch s a Monday nigh p io o bed ime; he da a we e downloaded, and he de ices cha ged, p io o hei e u n o pa icipan s upon waking Tuesday mo ning. Non-wea ime was de e mined as mo e han h ee hou s o consecu i e ‘0 0 o al accele a ion pe day, excep Monday and Tuesday, whe e In . J. En i on. Res. Public Heal h 2022,19, 7360 4 o 10 eigh hou s was used o accoun o downloading and cha ging ime. The 3 h non-wea h eshold is mo e s ingen han he s anda d minimum 10 h/day o al wea ime o en used in ee-li ing adul s [19]. Subjec i e assessmen o aining demands was quan i ied ia Ra ing o Pe cei ed Exe ion (RPE) [ 20 ] p io o bed each day as close o 10:00 p.m. as p ac icable using pen and pape . RPE is an indica o o exe ion and was used o add con ex o EE each day. Pa icipan s used a ca ego y a io scale (CR-10) o 0 o 10 o a e hei exe ion o he day whe e 0 = ‘no hing a all’, 2 = ‘weak’, 5 = ‘s ong’, 7 = ‘ e y s ong’ and 10 = ‘ e y, e y s ong’. While his measu e has his o ically been used o a e a single aining ‘session’, i has been p e iously u ilized as a daily measu e in mili a y se ings [21,22]. Subjec i e wellbeing was assessed using he Mul i-componen T aining Dis ess Scale (MTDS), which is a alida ed measu e o a hle e popula ions [ 15 ] and has p e iously been used o i e igh e s [ 23 ]. The sho 22-i em measu e was comple ed ia pen and pape upon wakening e e y Sunday mo ning o he du a ion o he s udy. Twen y- wo i ems, g ouped unde six ac o s: dep ession, igo , physical symp oms, sleep dis u bances, s ess and a igue we e answe ed on a i e-poin scale (ze o o ou : 0 = ‘no a all’, 1 = ‘a li le’, 2 = ‘mode a ely’, 3 = ‘qui e a bi ’, 4 = ‘ex emely’). In e nal consis ency o he subscales ha e p e iously been epo ed wi h C onbach alpha anging om 0.72 o 0.86 [15]. Physical i ness was assessed in weeks 2 and 8 o BMT. The physical i ness es s included maximum push-ups and si -ups ( ee held) in wo minu es, and he mul i-s age shu le un (i.e., he Beep es ) [ 9 ]. Mul i-s age shu le un pe o mance was used o p edic VO2peak [24]. 2.3. Da a Analysis All s a is ical analyses we e pe o med using SPSS so wa e (IBM SPSS S a is ics o Windows, Ve sion 26.0, 2019, A monk, NY, USA). Pa icipan s wi h da a om ≥ 75% o BMT we e included in he analysis o adequa ely ep esen BMT. All da a and hei esiduals we e checked o no mali y. To de e mine changes in physical i ness, a epea ed measu e ANOVA was conduc ed. In cases whe e Mauchly’s es s o sphe ici y indica ed ha sphe ici y had been iola ed (p< 0.001), mul i a ia e es s a e epo ed in he o m o he Huynh–Feld co ec ion. Whe e he e was a signi ican change o e ime, pos hoc analyses we e conduc ed using he Bon e oni adjus men . Fo assessing he changes in subjec i e wellbeing and aining demands ac oss he wel e weeks o BMT (aim 1a and 1b), linea mixed models we e used. Pai wise compa isons wi h a signi icance le el o p= 0.05 using a Bon e oni co ec ion we e u ilized i a main e ec o ime was p esen (p< 0.05). To explo e ela ionships be ween aining demands and subjec i e wellbeing (Aim 2), linea mixed models we e employed. Fo subjec i e wellbeing, he MTDS o al sco e was u ilized as he ou come a iable. A i s o de au o eg essi e co a iance s uc u e was u ilized o he epea ed measu es o imepoin s, due o a educ ion in co a iance o inc easing imepoin lags o he uns uc u ed ma ix. Bo h singula p edic o s and an o e all model o bes i we e used o de e mine which indices o aining demands and indi idual cha ac e is ics p edic ed MTDS o al sco e. Fo singula p edic o s, each a iable in solida i y was assessed on i s p edic i e capaci y o MTDS o al sco e. Fo he model o bes i , all possible models comp ising combina ions o indices o aining demands, physical i ness, age, gende , and BMI a iables we e c ea ed. Models we e compa ed o achie e he lowes Akaike’s In o ma ion C i e ion (AIC), an indica ion o model i ha accoun s o model pa simoniousness. The ixed e ec s o he mos pa simonious model wi h he lowes AIC a e epo ed. Fo ixed e ec s o he indi idual p edic o s and he o e all model o bes i , F-s a is ics (F), coe icien s (ß) and p alues (p) a e epo ed wi h he signi icance se a p= 0.05. In . J. En i on. Res. Public Heal h 2022,19, 7360 5 o 10 3. Resul s O he 48 ec ui s who pa icipa ed in he s udy, 35 ec ui s (29 men and 6 women; aged 24.8 ± 6.8 y; heigh 177.38 ± 10.1 cm; body mass 75.6 ± 14.7 kg) had da a o ≥ 75% o BMT and we e included in he analysis. All ma ke s o aining demands changed (p< 0.05) du ing BMT. Pai wise compa isons be ween weeks o physical ac i i y, subjec i e assessmen s o aining demands and wellbeing a e depic ed in Figu es 1and 2. Physical i ness as measu ed by push-ups, si -ups, and p edic ed VO 2peak imp o ed be ween weeks wo and eigh . Pa icipan s comple ed 5.4 ± 1.7 mo e (p= 0.003) push-ups. Simila ly, ec ui si -up pe o mance also signi ican ly imp o ed (p< 0.001),wi h pa icipan s a e age si -up pe o mance mo e han doubling du ing he same pe iod o ime. Es ima ed VO 2peak , as measu ed by he beep es , also signi ican ly inc eased o e ime (p< 0.001), wi h a mean imp o emen o 4.96 mL.kg−1.min−1. Figu e 1. Physical ac i i y measu es ac oss he 12 week BMT p og am (mean ± 95% con idence in e als). No e: Numbe s abo e da a poin s deno e a signi ican di e ence o he de ailed week (p< 0.05). Signi ican singula p edic o s o MTDS o al included daily s eps (F = 14.92, ß = 0.001, p< 0.001), % igo ous physical ac i i y (F = 8.63, ß = − 141.3, p= 0.004), NASA TLX (F = 46.08, ß = 0.26, p< 0.001), RPE (F = 33.65, ß = 2.03, p< 0.001) and gende (F = 6.01, ß = 9.54, p= 0.020); wi h emales mo e likely o epo highe MTDS o al sco es. The o e all model o bes i o p edic ing MTDS o al sco e is de ailed in Table 2. Table 2. Model o bes i o p edic ing MTDS o al sco e. P edic o Va iable Fixed E ec Measu es F ß p In e cep 0.12 −2.093 0.734 NASA TLX 15.27 0.229 <0.001 * Daily s eps 9.70 0.001 0.002 * % Vigo ous ac i i y 8.05 −140.175 0.005 * % Mode a e ac i i y 3.37 −56.335 0.067 % Ligh ac i i y 0.42 5.843 0.516 RPE 1.22 0.594 0.270 Gende 1.78 5.450 0.192 Push up pe o mance change 1.53 −0.180 0.225 Model AIC 2157.519 No e: NASA TLX, Na ional Ae onau ical Space Agency ask load index; RPE, a ing o pe cei ed exe ion; AIC, Akaike’s In o ma ion C i e ion. * indica es signi icance a p< 0.01. In . J. En i on. Res. Public Heal h 2022,19, 7360 6 o 10 Figu e 2. Changes in subjec i e assessmen s o aining demands and wellbeing ac oss he 12-week BMT p og am (mean ± 95% con idence in e als). No e: RPE, a ing o pe cei ed exe ion; MTDS, mul i-componen aining dis ess scale; NASA TLX, Na ional Ae onau ical Space Agency ask load index; au, a bi a y uni s. Numbe s abo e da a poin s deno e a signi ican di e ence o he de ailed week (p< 0.05). 4. Discussion This s udy is he i s o sys ema ically cha ac e ize he physical demands o aining du ing he Aus alian A my BMT p og am (weeks 2–12), p o iding bo h accele ome y- de i ed and subjec i e measu es. Acco dingly, he p ima y aim o his s udy was o quan i y he physical demands imposed on ec ui s, and changes in ec ui esponses (subjec i e wellbeing and physical i ness) ac oss he 12 weeks o BMT. Resul s showed ha ec ui s we e exposed o high olumes o physical ac i i y du ing BMT (~17,000 s eps · day −1 and ~18 MJ · day −1 ). Resul s also indica ed ha all indices o he aining demands changed signi ican ly o e he 12 weeks. Impo an ly, subjec i e wellbeing imp o ed du ing BMT, wi h weeks 6 and 12 p o iding eco e y oppo uni ies. The second aim o his s udy was o explo e ela ionships be ween he aining demands and subjec i e wellbeing. T aining demands we e associa ed wi h subjec i e measu es o wellbeing, suppo ing he po en ial u ili y o measu es o subjec i e wellbeing o manage ec ui s ain du ing BMT, which is consis en wi h heo e ical expec a ions. Rec ui s a e aged 17,031 s eps pe day du ing BMT, which is highe han ecen s udies in Aus alian, B i ish, and U.S. ec ui s (10,000–14,000 s eps pe day) [ 9 , 21 , 25 , 26 ]. Howe e , he physical ac i i y in ensi y dis ibu ion was simila o ecen esul s om he U.S. A my BMT, wi h he majo i y o ac i i y classi ied as ‘seden a y’ o ‘ligh ’ [ 25 ]. Consis en wi h s eps, accele ome e -de i ed ene gy expendi u e was also highe han a ecen s udy o U.S. A my ec ui s (~18 MJ s. ~14 MJ pe day) [ 26 ] bu simila o ene gy expendi u e in B i ish A my ec ui s measu ed by doubly-labelled wa e [ 21 ]. I is acknowledged ha di ec compa ison o o he BMT p og ams is di icul due o p og amma ic and me hodological di e ences [ 27 ], bu hese p e ious indings help o con ex ualize he cu en indings. Rega dless, hese indings clea ly demons a e ha Aus alian A my ec ui s a e exposed o a high olume o physical ac i i y du ing BMT, albei mos ly low in ensi y. This olume o physical ac i i y is likely o ep esen a la ge inc ease in habi ual ac i i y le els o many ec ui s based on ends in he gene al popula ion [25,28]. In . J. En i on. Res. Public Heal h 2022,19, 7360 7 o 10 Challenging aining s imuli ollowed by adequa e eco e y pe iods can elici im- p o ed physical pe o mance and dec ease inju y p e alence when compa ed wi h con- di ions o inadequa e eco e y [ 6 ]. On a e age, ec ui s’ physical i ness signi ican ly inc eased om week 2 o week 8 o BMT, which sugges s ha he aining s imuli imposed was su icien o elici posi i e adap a ions o mos ec ui s. This p o ides a leas pa ial suppo o he e ec i eness o he cu en BMT p og am o p o ide a pe iodized aining s imulus wi h adequa e eco e y oppo uni y. Howe e , he e is some di e gence in he p esc ibed weekly PT demand and he o al physical demand o ha week, pa icula ly in weeks wo o i e. This obse a ion is suppo ed by p e ious s udies showing ha PT ep esen s a ela i ely small p opo ion o he scheduled aining p og am, and i is ac i i ies ou side o PT (e.g., load ca iage, ield and comba aining, d ill, walking) ha can impose g ea e aining s ess [ 2 , 9 , 29 ]. I has been no ed ha ec ui s appea o be mos suscep ible o inju y du ing he i s i e o six weeks o BMT [ 30 – 32 ]; o example Hall [ 30 ] epo ed ha 71% o inju ies in B i ish A my ec ui s occu wi hin he i s six weeks o BMT. The cu en s udy obse ed a change in pe cep ion o e o o e BMT, which is consis- en wi h p e ious s udies in ec ui s unde aking BMT [ 21 ] and consc ip s unde aking ield aining [ 22 ]. Howe e , a he han iden i ying weeks o in ensi ied aining demands, he cu en esul s e ealed weeks o dec eased pe cep ion o e o , appea ing o o e ec ui s an oppo uni y o eco e om he demands o BMT. High aining demands ha e been shown o inc ease mood dis u bance du ing mili a y aining [ 11 , 33 ], and symp oms o o e eaching ha e been epo ed p e iously in ec ui coho s [ 11 , 12 ]. Consis en wi h hese p e ious indings, he MTDS was sensi i e o weekly a ia ions in aining demands. This was ue o he o al MTDS sco e and he indi idual subscales o dep essed moods, igo , physical signs and symp oms, and sleep dis u bances. The p og essi e imp o emen in subjec i e wellness measu es o e he i s ou weeks is likely o ep esen a pe iod o adjus men o he new aining en i onmen [ 34 ], and he ansi ion om ci ilian li e o he mili a y aining en i onmen , which supe imposes a a ie y o addi ional s esso s on op o he physical demands [3,35]. MTDS o al sco es we e lowes in weeks 6 and 12, which coincided wi h he weeks o lowes physical demands. This is simila o he indings o O’Lea y e al. [ 21 ] who obse ed a mode a e associa ion be ween pe cei ed aining demands and dis ance a elled. In he same s udy, daily RPE was also associa ed wi h TRIMP and %HRR. In he cu en s udy, he g ea es aining dis ess (i.e., MTDS o al sco e) was epo ed in week 10, which included he i s hal o he ield aining phase. Anecdo ally, he ield- aining phase is he mos challenging componen o BMT o ec ui s as i in ol es dis up ed sleep and nu i ion combined wi h a ious physical and cogni i e s esso s. The esul s o he cu en s udy indica e ha he MTDS o al sco e e lec s he s ain associa ed wi h he mul i- s esso aining en i onmen (i.e., PT, mili a y skills and educa ion classes, inciden al PA, psychological and cogni i e demands), no jus he physical demands o aining. The e o e, he esul s suppo he e ec i eness o he mul i-dimensional wellbeing ques ionnai e in cap u ing a ious ac o s ha in luence o al subjec i e wellbeing. The cu en indings suppo he po en ial u ili y o subjec i e wellbeing as a cos -and ime-e ec i e ool o he ongoing moni o ing o ec ui s. I builds on he p e ious esea ch o Ojanen e al. [ 12 ] who epo ed an inc ease in pe cep ions o exe ion du ing mul i- s esso mili a y aining. The obse ed inc eases in dep essed moods wi h inc eases in aining load, a e consis en wi h p e ious li e a u e examining he e ec s o high aining demands, o po en ial o e aining, whe e he accumula ion o s esso s ha e he po en ial o exceed an indi idual’s capaci y o cope [ 36 , 37 ]. Simila ly, he ela ionship be ween sel - epo ed physical signs and symp oms o aining s ess and indices o aining demands in he cu en s udy a e consis en wi h p e ious indings in mili a y con ex s. Inc eases in muscle so eness ha e been shown o inc ease when load and EE a e inc eased du ing s enuous win e mili a y aining [ 38 ]. The lack o signi icance o ligh physical ac i i y po en ially suppo s he sensi i i y o he MTDS physical signs and symp oms subscale. In . J. En i on. Res. Public Heal h 2022,19, 7360 8 o 10 5. Conclusions In summa y, he aining demands imposed ac oss Aus alian A my BMT a ied ac oss he 12 weeks and e lec ed in ended pe iodiza ion o aining and eco e y. The six h and wel h weeks p o ided an oppo uni y o eco e om he mul i-s esso aining en i onmen , as demons a ed by he lowe physical demands combined wi h imp o ed subjec i e wellbeing. Physical i ness imp o ed om week 2 o week 8, indica ing a posi i e aining e ec om he BMT p og am. Sel - epo ed measu es we e sensi i e o luc ua ions in aining s esso s consis en wi h heo e ical expec a ions. The MTDS exhibi ed signi - ican associa ions wi h indices o aining demands (i.e., ligh PA, mode a e PA, weekly EE and RPE). Simila o applied spo con ex s, subjec i e measu es o s ess esponses may o e mo e u ili y o indi idual managemen o pe sonnel han quan i ica ion o aining s esso s in he mili a y aining en i onmen . The daily use o accele ome e s and mul i-domain sel - epo ools may, he e o e, help o be e manage how ec ui s a e coping wi h he demands o aining du ing BMT, p o iding oppo uni ies o he ea ly iden i ica ion o ec ui s a isk o inju y, maladap a ion o a i ion. Au ho Con ibu ions: L.C.M., S.B., P.B.G. and J.R.D. concei ed and designed esea ch. S.B., wi h assis ance om L.C.M., J.R.D., J.L.T., S.L.C. and P.B.G. comple ed da a collec ion. S.B., T.R., S.L.C. and L.C.M. p ocessed and analysed he da a, wi h assis ance on in e p e a ion o he esul s by J.R.D., J.L.T., P.B.G. and B.A., S.B., L.C.M. and J.R.D. w o e he manusc ip . All au ho s ha e ead and ag eed o he published e sion o he manusc ip . Funding: This wo k was suppo ed by a Human Pe o mance Resea ch Ne wo k g an om he Commonweal h o Aus alia ep esen ed by The De ence and Science Technology G oup o he Depa men o De ence. Ins i u ional Re iew Boa d S a emen : This s udy was app o ed by he Depa men o De ence and Ve e an’s A ai s Human Resea ch E hics Commi ee (021-17), and pa icipan s ga e in o med consen . In o med Consen S a emen : W i en in o med consen was ob ained om all subjec s in ol ed in he s udy. Da a A ailabili y S a emen : The da a a e no publicly a ailable. 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