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Moni o ing a igue s a e wi h hea a e‐based and subjec i e me hods du ing
in ensi ied aining in ec ea ional unne s
© 2024 The Au ho s. Eu opean Jou nal o Spo Science published by Wiley‐VCH GmbH on behal o Eu opean College o Spo Science
Published e sion
Nuu ila, Olli‐Pekka; Uusi alo, A ja; Kokkonen, Veli‐Pekka; Wee a a hna,
Nilushika; Ky öläinen, Heikki
Nuu ila, O., Uusi alo, A., Kokkonen, V., Wee a a hna, N., & Ky öläinen, H. (2024). Moni o ing
a igue s a e wi h hea a e‐based and subjec i e me hods du ing in ensi ied aining in
ec ea ional unne s. Eu opean Jou nal o Spo Science, Ea ly online.
h ps://doi.o g/10.1002/ejsc.12115
2024
Recei ed: 31 Janua y 2024
-
Re ised: 13 Ma ch 2024
-
Accep ed: 8 Ap il 2024
DOI: 10.1002/ejsc.12115
ORIGINAL PAPER
Moni o ing a igue s a e wi h hea a e‐based and
subjec i e me hods du ing in ensi ied aining in ec ea ional
unne s
Olli‐Pekka Nuu ila
1,2
|A ja Uusi alo
3,4
|Veli‐Pekka Kokkonen
1
|
Nilushika Wee a a hna
1
|Heikki Ky öläinen
1
1
Facul y o Spo and Heal h Sciences,
Uni e si y o Jy äskylä, Jy äskylä, Finland
2
The UKK Ins i u e o Heal h P omo ion
Resea ch, Tampe e, Finland
3
Depa men o Spo s and Exe cise Medicine,
Clinicum, Uni e si y o Helsinki, Helsinki,
Finland
4
Helsinki Clinic o Spo s and Exe cise
Medicine, Founda ion o Spo s and Exe cise
Medicine, Helsinki, Finland
Co espondence
Olli‐Pekka Nuu ila, Facul y o Spo and
Heal h Sciences, Uni e si y o Jy äskylä, P.O.
Box 35 (VIV), Jy äskylä 40014, Finland.
Email: [email p o ec ed]
Funding in o ma ion
Pola Elec o Oy; The Finnish Spo s Resea ch
Founda ion; The Founda ion o Spo s
Ins i u e
Abs ac
The pu pose o his s udy was i s ly o examine he sensi i i y o hea a e (HR)‐
based and subjec i e moni o ing ma ke s o in ensi ied endu ance aining; and
secondly, o in es iga e he alidi y o hese ma ke s o dis inguish indi iduals in
di e en a igue s a es. A o al o 24 ec ea ional unne s pe o med a 3‐week
baseline pe iod, a 2‐week o e load pe iod, and a 1‐week eco e y pe iod. Pe o -
mance was assessed be o e and a e each pe iod wi h a 3000m unning es . Re-
co e y was moni o ed wi h daily o hos a ic es s, noc u nal HR eco dings,
ques ionnai es, and exe cise da a. The pa icipan s we e di ided in o subg oups
(o e eached/OR, n=8; esponde s/RESP, n=12) based on he changes in pe -
o mance and subjec i e eco e y. The esponses o he second week o he
o e load pe iod we e compa ed be ween he subg oups. RESP imp o ed hei
baseline 3000 m ime (p<0.001) a e he o e load pe iod (−2.5 �1.0%), and he
change di e ed (p<0.001) om OR (0.6 �1.2%). The changes in noc u nal HR (OR
3.2 �3.1%; RESP −2.8 �3.7%, p=0.002) and HR a iabili y (OR −0.7 �1.8%; RESP
2.1 �1.6%, p=0.011) di e ed be ween he subg oups. In addi ion, he dec ease in
subjec i e eadiness o ain (p=0.009) and inc ease in so eness o he legs
(p=0.04) we e g ea e in OR compa ed o RESP. Noc u nal HR, eadiness o ain,
and exe cise‐de i ed HR‐ unning powe index had ≥85% posi i e and nega i e
p edic i e alues in he disc imina ion be ween OR and RESP indi iduals. In
conclusion, exe cise ole ance can a y subs an ially in ec ea ional unne s. The
esul s suppo ed he use ulness o noc u nal HR and subjec i e eco e y assess-
men s in ecognizing a igue s a es.
KEYWORDS
a igue, o e aining, pe o mance, physiology, eco e y
This is an open access a icle unde he e ms o he C ea i e Commons A ibu ion License, which pe mi s use, dis ibu ion and ep oduc ion in any medium, p o-
ided he o iginal wo k is p ope ly ci ed.
© 2024 The Au ho s. Eu opean Jou nal o Spo Science published by Wiley‐VCH GmbH on behal o Eu opean College o Spo Science.
Eu J Spo Sci. 2024;1–13. wileyonlinelib a y.com/jou nal/ejsc
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1
Highligh s
�Tole ance o simila ly inc eased aining load a ies in ec ea ional unne s. While some
indi iduals espond posi i ely, o o he s he same load may be excessi e.
�Subjec i e ma ke s, such as eadiness o ain and so eness o he legs, we e he mos
sensi i e ma ke s o espond o inc eased aining load, and he magni ude o hese e-
sponses was g ea e in indi iduals wi h suspec ed o e eaching.
�Res ing o exe cise hea a e (HR) did no espond as sys ema ically as he subjec i e
ma ke s o he aining load i sel . Howe e , he changes in noc u nal HR, noc u nal HRV,
and HR‐ unning powe index s a ed o di e be ween he RESP and OR subg oups a an
ea lie s age o he o e load pe iod suppo ing hei use ulness as indica o s o he a igue
s a e.
1
|
INTRODUCTION
Classic ma hema ical aining models assume ha once an indi idual
is exposed o a ce ain exe cise dose, i esul s in posi i e esponses
in i ness, which can be ealized a e he alle ia ion o a igue (Taha
e al., 2003). The s a e o a igue is ypically conside ed as a con-
inuum, and he le el o a igue is de ined based on changes in pe -
o mance and he ime needed o eco e (Bellinge , 2020; Meeusen
e al., 2013). Fo diagnos ic pu poses, pe cei ed eco e y o mood is
o en e alua ed along wi h he pe o mance (Aub y e al., 2015;
Bellinge , 2020; Coa es, Hammond, & Bu , 2018). A s a e in which
he pe cei ed a igue migh be inc eased abo e no mal, bu pe o -
mance is unchanged o imp o ed is called acu e a igue, and i occu s
basically a e each aining session bu ades wi hin day(s). I
incomple e eco e y accumula es long enough, he nex s age o a-
igue is ega ded as o e eaching (OR), which in he case o unc-
ional OR (FOR) akes om a ew days o a ew weeks o eco e , bu
du ing non unc ional OR (NFOR) he eco e y pe iod is subs an ially
longe (i.e., weeks‐ o‐mon hs). (Meeusen e al., 2013).
Al hough some s udies ha e ound signi ican imp o emen s a -
e he eco e y pe iod in FOR a hle es (Bellenge e al., 2016; Le
Meu e al., 2013), he bene i s o p esc ibed pe iods o FOR ha e
been ques ioned when compa ed o aining ha induces b ie pe-
iods o acu e a igue only (Bellinge , 2020; Bellinge e al., 2020).
La ely, FOR has also been connec ed o se e al un a o able physio-
logical esponses, such as inc eased es ing a e ial s i ness (Coa es,
Milla , & Bu , 2018), mi ochond ial unc ional impai men (Flockha
e al., 2022), dec eased glucose ole ance (Flockha e al., 2022), and
highe p e alence o uppe espi a o y ac in ec ions (Hausswi h
e al., 2014). The e o e, ma ke s ha a e sensi i e and speci ic o he
p edic ion o OR could be use ul by suppo ing he p esc ip ion o
sus ainable aining p og ams.
The e olu ion o wea able echnology has p o ided a lo o al-
e na i es o he moni o ing o aining and eco e y. Among
endu ance aining, he mos ypical echnologies a e ela ed o hea
a e (HR) eco dings a es o du ing exe cise. Al hough many
s udies suppo he use ulness o HR‐based ma ke s (Buchhei , 2014;
Düking e al., 2021; Nuu ila e al., 2022a), esea ch e idence is
somewha con lic ing ega ding hei accu acy in he iden i ica ion o
a igue s a es. Acco ding o e iews by Bosque e al. (2008) and
Roe e e al. (2021), HR measu emen s du ing es o exe cise would
no appea o be su icien in he de ec ion o FOR, indi idually. In
line wi h ha , Bellenge e al. (2016) ha e also sugges ed ha e-
sponses in he HR‐based ma ke s should be con ex ualized wi h
pe cei ed eco e y as simila esponses (dec ease in HR and inc ease
in HRV) can be associa ed wi h posi i e aining adap a ions and he
s a e o FOR. In gene al, subjec i e ma ke s ha e been ound o be
mo e sensi i e han objec i e measu es in esponding o changes in
aining load (Saw e al., 2016). Howe e , i is c i ical o acknowledge
ha no jus he sensi i i y o a ce ain (ex e nal) aining load is
impo an . E en mo e ele an would be he speci ici y o he ma ke
o dis inguish excessi e load om sus ainable load o an indi idual,
as he homeos a ic s ess induced by a ce ain aining load and
abili y o eco e is highly a iable be ween indi iduals (Mann
e al., 2014).
The con lic ing esul s ega ding he abili y o HR‐based ma ke s
o iden i y a igue s a es could, a leas pa ly, ela e o he me h-
odology. Fo example, s udies examining es ing HR/HRV ha e
mos ly ocused on mo ning eco dings (Roe e e al., 2021), while he
use ulness o day‐ o‐day noc u nal eco dings emains a he un-
known. Mo eo e , he assessmen o a eliable baseline is o impo -
ance in HR‐based ma ke s, and ins ead o single isola ed esul s,
longe a e aging pe iods migh be necessa y (Man esa‐Rocamo a
e al., 2021). Some s udies ha e induced so called “pa asympa he ic
hype ac i i y” a he s a e o FOR (Bellenge e al., 2016; Le Meu
e al., 2013), meaning dec eased HR and inc eased HRV along wi h
impai ed pe o mance. Howe e , i is inconclusi e how condi ional
he phenomenon is o me hodologies ( eco ding condi ion), aining
execu ion ( equency, in ensi y, and olume), and backg ound o he
pa icipan s (well‐ ained s. ec ea ional). Fu he mo e, as calo ic
es ic ion (Ma hisen e al., 2020) and ela i e ene gy de iciency
(S ein e al., 2012) ha e been associa ed wi h inc eased pa a-
sympa he ic ac i i y, low ene gy a ailabili y could explain some o
he con adic o ies obse ed du ing pe iods o excessi ely high
aining loads.
The pu pose o his s udy was o examine he sensi i i y o HR‐
based and subjec i e moni o ing ma ke s o in ensi ied endu ance
aining. Fu he mo e, he capabili y o hese ma ke s o di e en ia e
2
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be ween indi iduals o di e se a igue s a es and he op imal cu ‐o
alues o classi y indi iduals co ec ly we e in es iga ed.
2
|
MATERIALS AND METHODS
2.1
|
Pa icipan s
A o al o 32 (18 males and 14 emales) ec ea ional unne s we e
ec ui ed o pa icipa e in he s udy. The pa icipan s we e heal hy,
aged 20–45 (men) o 20–50 (women), and ained egula ly by
unning. The heal h s a us o all indi iduals willing o pa icipa e was
sc eened ia a ques ionnai e o exclude any diseases o egula
medica ions ha could ha e a ec ed he pa icipa ion. In addi ion,
hei es ing elec oca diog aphy was eco ded and app o ed by a
physician be o e inal accep ance. F om he 32 pa icipan s ha we e
sc eened, he e we e 8 d opou s. The easons o he d opou s we e
challenges wi h he ime able (n=2), heal h issues un ela ed o he
s udy (n=2), and inju ies/so eness o he legs (n=4). The baseline
cha ac e is ics o he pa icipan s who pe o med he whole s udy
pe iod and a ended all he es s a e p esen ed in Table 1. All he
pa icipan s ga e hei w i en consen o pa icipa e, and he s udy
p o ocol was app o ed by he e hics commi ee o he Uni e si y o
Jy äskylä.
2.2
|
S udy p o ocol
The s udy consis ed o h ee dis inc phases: a 3‐week baseline
aining pe iod (BL), a 2‐week o e load pe iod (OL), and a 1‐week
eco e y pe iod (REC) (Figu e 1). Each pe iod was ollowed by a
es day (T1–T3) du ing which maximal endu ance pe o mance was
assessed wi h a 3000 m unning es . In addi ion, amilia iza ion es s
(T0) and a maximal inc emen al eadmill es we e pe o med be o e
he BL. T aining and eco e y we e moni o ed h oughou he s udy
pe iod by mo ning o hos a ic es s and nigh HR and HRV e-
co dings, subjec i e eco e y ques ionnai es, exe cise da a, and
weekly con ol unning es s (C1–C6).
2.3
|
T aining p o ocol
The aining p og am was designed based on p e ious aining in-
e en ions aiming o induce a momen a y o e load (Bellenge
e al., 2016; Bou dillon e al., 2018; Dupuy e al., 2013; Le Meu
e al., 2013). Fu he mo e, he aim was o induce o e eaching in
some indi iduals bu also allow some indi iduals o espond posi-
i ely despi e compa able inc ease in hei aining load. Du ing BL,
he pa icipan s exe cised a hei egula equency and olume (4–6
sessions pe week). The in ensi y o he aining was limi ed o low
in ensi y (HR < i s lac a e h eshold), excep o he weekly con ol
exe cise which consis ed o a sel ‐paced wa m‐up and 6x3‐min
TABLE 1Baseline cha ac e is ics o he pa icipan s.
Females (n=10) Males (n=14) All (n=24)
Age (y s.) 39 �8 39 �5 39 �6
Heigh (cm) 165 �8 179 �7 173 �10
Body mass (kg) 62.6 �8.5 80.0 �12.7 72.8 �14.0
Fa (%) 24.7 �5.2 14.7 �3.8 18.8 �6.7
VO
2max
(ml/kg/min) 43.1 �3.4 51.2 �8.3 47.8 �7.8
FIGURE 1 S udy design. T0–T3 e e s o es days, when he 3000 m unning es and eac i i y jump es we e pe o med. C1–C6 e e s
o con ol unning es s which consis ed o a submaximal unning es , coun e mo emen jump es , and 6x3‐min high‐in ensi y in e al
aining session. Du ing he baseline pe iod, aining load o he 3 d week was sligh ly dec eased (−20%) o ensu e su icien eco e y be o e
he o e load pe iod.
EUROPEAN JOURNAL OF SPORT SCIENCE
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maximum sus ainable e o in e als. The in ensi y es ic ion was
in ended o ensu e su icien aining eadiness o OL.
Du ing he OL, he aining load was inc eased ia bo h he
in ensi y and he olume o aining. The planned inc ease in he
aining load was 80% compa ed o BL as de e mined by he o -
mula o Lucia e al. (2003) whe e he minu es spen a di e en
in ensi y zones (zone 1 =1, Zone 2 =2, and Zone 3 =3) ha e hei
own weigh coe icien s. An inc ease o aining olume was s an-
da dized o 45%. The weekly aining p og am du ing he OL con-
sis ed o a con ol session, 3–4 mode a e‐in ensi y sessions (HR
be ween lac a e h esholds), and 1–2 low‐in ensi y sessions. The
mode a e‐in ensi y sessions we e 6‐and 12‐min in e als wi h a 3‐
min ac i e eco e y o con inuous >30 min sessions. All he
mode a e‐in ensi y sessions included a 15–20‐min wa m‐up and
cool‐down. The aining equency and he o al olume o each
aining session we e de ined acco ding o he aining du ing he
BL and he abo e‐men ioned c i e ia. A e he OL, he aining load
as Lucia's TRIMP was dec eased du ing he REC by 40% compa ed
o BL. Excep o he con ol session, he aining was pe o med as
low‐in ensi y aining.
2.4
|
Pe o mance es s
An inc emen al eadmill es was pe o med be o e he s a o BL o
de e mine indi idual HR zones. Du ing he same isi , he pa ici-
pan 's a pe cen age was es ima ed wi h skin old measu emen s
(Du nin e al., 1967). The eadmill es s a ed a 7 km/h ( emales) o
8 km/h (males), a e which he eadmill speed was inc eased by
1 km/h e e y 3 min, and he es con inued un il oli ional exhaus-
ion. The incline was kep cons an a 0.5°. The eadmill was s opped
be ween each s age o d awing blood samples om he inge ip o
lac a e analyses (Biosen S_line Lab þlac a e analyze , EKF Diag-
nos ic). The HR (Pola H10, Pola Elec o Oy) and espi a o y gases
(Jaege Vyn us CPX, Ca eFusion Ge many 234 GmbH) we e also
measu ed con inuously du ing he es . The maximal oxygen up ake
(VO
2max
) was de ined as he highes 60‐s a e age o oxygen up ake
and he maximum HR as he highes obse ed alue du ing he es .
The lac a e h esholds (LT1 and LT2) we e de ined acco ding o he
c i e ia used in p e ious s udies (Nuu ila e al., 2022a,2022b;
Ves e inen e al., 2017).
T0–T3 es s ( eac i i y jumps þ3000 m) ook place always a he
same ime o he day wi hin‐indi idual (�2 h), and hey we e always
p eceded by a es day. Pa icipan s we e asked o ollow simila
nu i ional habi s on all es days. Since i is known ha low ene gy
a ailabili y can pa ly con ibu e o o e eaching (Ke unen
e al., 2021; Kuikman e al., 2022), he pa icipan s we e ad ised o
pay a en ion o su icien ene gy in ake du ing OL. Mo eo e , hey
ecei ed a calcula ion o he app oxima e inc ease in he daily ene gy
expendi u e ha was caused by he inc eased aining load. Body
mass ha was measu ed on a scale be o e each es was used as an
indi ec measu e o es ima e i he e had been indi iduals wi h sig-
ni ican ene gy de iciency.
Reac i i y jump (RJ powe ) es s we e pe o med a e a 3‐min
wa m up and wo submaximal se s o ~10 jumps. In he es , he
pa icipan s pe o med 10 epea ed jumps explosi ely wi h minimal
con ac ime. Hands we e held on hips and minimal bending on he
knees was allowed. Con ac imes and ligh imes we e analyzed
om a ideo ha was eco ded wi h slow‐mo ion came a (240 ps)
om he on and analyzed wi h MyJump Lab (Haynes e al., 2019).
The powe o each jump was calcula ed based on he o mula o
Bosco e al. (1983). The a e age o i e bes jumps was used in he
analyses. The in e and in aday eliabili y o he 10/5 epea ed jump
es p o ocol has been epo ed in he a hle ic popula ion (Sou hey
e al., 2023).
3000 m unning es s we e conduc ed in small g oups (max. Six
pe sons) in a 200‐m indoo ack (n=18) o in a 400‐m ou doo ack
(n=6) a e he eac i i y jump es . The ou doo ack was used o
some pa icipan s (in all es s) due o he summe lockdown o he
indoo ack ha was no known when he ime able o he da a
collec ion was designed. A s anda dized 15‐min low‐in ensi y wa m‐
up including 3 �20–30‐s accele a ions o he a ge speed was al-
ways pe o med be o e he es . Ve bal encou agemen and spli
imes we e gi en o all pa icipan s. The unning ime, a e age and
peak HR, and blood lac a e concen a ion (pos 2 min) we e analyzed
o each es . The 3000 m unning es was chosen as an indica o o
endu ance pe o mance due o i s easibili y, p e iously epo ed as
low coe icien o a ia ion (CV) (1.41%) in ec ea ional unne s
(Nuu ila e al., 2022b) and s ong associa ions wi h inc emen al
eadmill es a iables (Nuu ila e al., 2023).
2.5
|
T aining and eco e y moni o ing
The pa icipan s used an HR moni o (Van age V2, Pola Elec o Oy)
and HR s ap (H10) in all aining sessions. The ime in HR zones
(1 <LT1, 2 =LT1‐LT2, and 3 >LT2) and he dis ance co e ed we e
analyzed o all he sessions. In addi ion, he a e age HR and unning
powe o whole sessions (con inuous low‐in ensi y) o wa m‐up
(mode a e‐in ensi y) we e analyzed o calcula e a simila a iable
as he HR‐ unning speed index (Ves e inen e al., 2014) by eplacing
he unning speed wi h unning powe in he o mula. The HR‐
unning powe index basically demons a es he di e ence be-
ween heo e ical and measu ed unning powe a a ce ain HR based
on he indi idual's s anding HR (BL a e age), maximum HR, and
maximum speed o he inc emen al eadmill es con e ed o
unning powe in he Pola Flow so wa e. The unning powe was
used ins ead o unning speed o allow a ai e compa ison be ween
possibly di e ing e ains. An example o HR‐ unning powe index
calcula ion is demons a ed in he Suppo ing In o ma ion S1.
Noc u nal HR eco dings we e pe o med wi h alida ed (Nuu ila
e al., 2021) pho ople hysmog aphy‐based w is measu emen (Pola
Van age V2). The esul s (HR, LnRMSSD) we e analyzed sepa a ely
o he ull nigh and a 4‐h pe iod which s a ed 30 min a e he
de ec ed sleep onse (Nuu ila e al., 2022c) ha was based on an
au oma ic algo i hm (Pesonen e al., 2018). The esul s we e i s
4
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synced om he wa ch o Pola Flow so wa e, a e which consec-
u i e 5‐min a e ages o he noc u nal eco ding da a we e au o-
ma ically ans o med o Coach4P o so wa e (Coach4P o Oy, Espoo,
Finland).
In he o hos a ic es , he pa icipan s collec ed RR‐in e al da a
o 2 min in he supine and s anding posi ions. Be o e he measu e-
men , he pa icipan s we e ins uc ed o emp y hei u ina y bladde
and a e ha go back o bed and wai o app oxima ely 1 min
be o e s a ing he eco ding. The da a was collec ed by using an
ECG‐based HR‐senso (Pola H10) and he “o hos a ic es ” ea u e
o he wa ch (Pola Van age V2). The esul s we e analyzed o mean
HR and LnRMSSD du ing he second minu e o he supine and
s anding posi ions.
The con ol unning es consis ed o a a ing o a pe cei ed
exe ion (RPE)‐based submaximal unning es , coun e mo emen
jumps (CMJs), and a 6x3‐min maximal sus ainable e o in e al
exe cise. The es was ins uc ed o be pe o med once a week in he
same o simila en i onmen and a he same ime o day (�2 h)
wi hin an indi idual. The RPE‐based es was de eloped om he
p o ocols o Sangan e al. (2021) and Ves e inen e al. (2017). I
in ol ed wo 6‐min s ages and one 3‐min s age wi h in ensi ies
de ined on he RPE scale as 9 ( e y ligh ), 13 (somewha ha d), and 17
( e y ha d). The a e age unning speed and he a e age HR we e
calcula ed sepa a ely o each s age (excluding he i s minu e o
each s age). The CMJ es (Pola Leg Reco e y Tes ) consis ing o
h ee maximal a emp s was pe o med be o e in e al exe cise. The
jump heigh was es ima ed au oma ically ia he ine ial measu e-
men uni in he wa ch (Pola Van age V2). The alidi y and eliabili y
o he me hod ha e been epo ed by G ube e al. (2022). A e he
CMJ es , he pa icipan s pe o med a 6x3‐min/2‐min eco e y in-
e al session a he maximum sus ainable e o . The a e age
unning speed and he a e age HR we e de e mined as he a e age
o all in e als. The a e age speed o he in e als has p e iously
co ela ed s ongly wi h he 3000 m unning pe o mance and i s
change (Nuu ila e al., 2023).
Subjec i e eco e y was assessed each mo ning a e he o ho-
s a ic es ia he Coach4P o applica ion. The a iables es ima ed on
a 1–5 scale we e as ollows: sleep quali y, gene al a igue, s ess
le el, eadiness o ain, so eness o he legs, and a igue o he leg
muscles. The scale logic was adap ed om Hoope e al. (1995):
Numbe h ee indica ed no mal pe cep ion, while inc ease indica ed
sligh ly o much wo se pe cep ion and dec ease indica ed sligh ly o
much be e pe cep ion. The pa icipan s we e ad ised o de ine
no mal he same way i was es ima ed a he beginning o he s udy
and no o upda e, o example, possibly inc easing a igue du ing he
s udy pe iod as he “new no mal”. In addi ion, aining‐speci ic
ques ions we e asked in he same ques ionnai e consis ing o ses-
sion RPE on a 0–10 scale (Fos e e al., 1996) and exe cise pe cep ion
(asking on a 1–5 scale) i p e ious session el as expec ed o be e
o wo se han expec ed. To ease he in e p e a ion o he esul s,
hey we e escaled o he analysis as ollows: No mal was de ined as
0 in all he ques ions, dec ease was de ined as a nega i e numbe
down o −2, and inc ease as a posi i e numbe up o 2 ega dless o
whe he he change should be conside ed as nega i e o posi i e in
pe cep ion (e.g., sligh ly inc eased so eness o he legs =1 s. sligh ly
imp o ed eadiness o ain =1).
2.6
|
Classi ica ion o a igue s a e
The classi ica ion o he a igue s a e was based on he changes in
pe o mance and subjec i e eco e y. Typically, he dec emen in
pe o mance ollowed by a ebound, a leas , o he baseline le el is
used as a c i e ion o FOR (Bellinge , 2020; Meeusen e al., 2013).
Howe e , as Coa es, Hammond, & Bu , 2018 ha e a gued, in ec-
ea ionally ained indi iduals his c i e ion may no be sui able
du ing o e load pe iods due o la ge inc eases in pe o mance, which
can “mask” he subsequen pe o mance dec emen s. The e o e, he
a igue s a e was diagnosed based on he o mula p oposed by
Coa es, Hammond, & Bu , 2018 bu modi ied o cu en es p o-
ocol as ollows: 3000 m ime (Δ%) [(T1–T2) þ(T3–T2)]. The o mula
combines he dec ease in unning pe o mance expec ed om T1 o
T2 wi h he supe ‐compensa ion expec ed a T3. I he change
de i ed om he o mula was g ea e han he smalles wo hwhile
change (0.3 �CV o T0–T1) (Hopkins, 2004) and he subjec i e
eadiness o ain was dec eased compa ed o BL ( en Haa
e al., 2017), he indi idual was de ined as o e eached (OR). A o al
o eigh pa icipan s (4 emales and 4 males) ul illed his c i e ion. To
compa e he OR subg oup wi h indi iduals who comple ed simila
inc emen in aining load du ing OL bu imp o ed hei pe o mance
om T1 mo e han he smalles wo hwhile change a T2 and T3, a
subg oup o esponde s (RESP) was o med. A o al o 12 pa icipan s
(3 emales and 9 males) ul illed his c i e ion lea ing ou pa ici-
pan s who could no be classi ied as OR o RESP ou o he subg oup
analysis. One o hese pa icipan s ul illed he pe o mance c i e ion
o OR, bu he subjec i e eadiness o ain imp o ed signi ican ly
om BL o OL. Two pa icipan s ul illed pe o mance c i e ion o
RESP a T2 bu no a T3 due o impai ed pe o mance. One
pa icipan did no imp o e pe o mance mo e han SWC a T2 bu
did no ha e supe compensa ion a T3 ei he . Ins ead o classi ying
unclea pa icipan s on case‐by‐case basis as OR o RESP, i was
conside ed mo e app op ia e o s ick o objec i e, ep oducible
c i e ia ha would allow mo e accu a e compa ison be ween in-
di iduals who in p ac ical e ms had meaning ully di e ing a igue
s a es.
2.7
|
S a is ical analyses
The esul s a e p esen ed as mean �s anda d de ia ion. The
no mali y o he da a was analyzed wi h Shapi o–Wilk es . The e -
ec s o he OL and REC pe iods we e analyzed by epea ed mea-
su es ANOVA wi h Bon e oni pos hoc es o i he a iables we e
no no mally dis ibu ed ( aining cha ac e is ics) by F iedman
nonpa ame ic es s. Fo he pe o mance es s, compa isons we e
pe o med be ween he T1–T3 ime poin s, and o he moni o ing
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a iables, he weekly a e ages du ing he OL (OL1 and OL2) and REC
pe iods we e compa ed o he a e age o BL. Weekly a e ages ha e
also been used in p e ious o e load s udies (Bellenge e al., 2016;
Bou dillon e al., 2018; Le Meu e al., 2013), and hey been sug-
ges ed o be me hodologically supe io compa ed o single‐day e-
sul s in he de ec ion o FOR (Man esa‐Rocamo a e al., 2021).
Be ween‐subg oup (OR s. RESP) di e ences in he changes om T1
o BL we e examined wi h simple con as s o in nonpa ame ic es s
wi h a Mann–Whi ney U‐ es . In addi ion, a ecei e ope a ing
cha ac e is ic (ROC) analysis (Hajian‐Tilaki, 2013) was pe o med o
examine how well each weekly measu ed moni o ing ma ke was
able o classi y he pa icipan nega i ely o posi i ely as o e -
eached. Fo he ma ke s ha had signi ican (p<0.05) a ea unde
he ROC cu e (AUC), an op imum cu ‐o alue was analyzed based
on he maximum Kolmogo o –Smi no me ic. Finally, using his cu ‐
o alue, posi i e and nega i e p edic i e alues we e analyzed. In
he esul s o es ing HR and HRV, one pa icipan (in OR subg oup)
was excluded om he analyses due o abno mally high HRV ha
p e en ed ob aining da a om he wa ch eco dings du ing he s udy
pe iod. S a is ical analyses we e pe o med wi h IBM SPSS S a is ics
.28 p og am (SPSS Inc).
3
|
RESULTS
3.1
|
T aining
The mean weekly aining cha ac e is ics o he o al g oup o pa -
icipan s and subg oups du ing each pe iod a e p esen ed in Table 2.
The weekly aining olume inc eased om BL du ing OL 44 �5%
(p<0.001). In u n, Lucia's TRIMP inc eased by 73 �11% (p<0.001)
and session RPE by 122 �44% (p<0.001). No di e ences we e
ound be ween he subg oups ega ding any aining cha ac e is ics
du ing he OL (p>0.157).
3.2
|
Running and jumping pe o mance
T1 3000‐m ime (p=0.610) o RJ powe (p=0.910) did no di e
be ween he subg oups. The 3000‐m ime dec eased signi ican ly in
he o al g oup o pa icipan s om T1 o T2 (−1.2 �1.7%, p=0.006)
and T1 o T3 (−1.7 �1.2%, p=0.002). The changes om T1 o T2
(OR 0.6 �1.2%; RESP −2.5 �1.0%) and T1 o T3 (OR ‐0.8 �1.6%;
RESP −3.1 �0.8%) di e ed be ween he subg oups (p<0.001), and
he unning ime emained unchanged in OR a T1–T3. The blood
lac a e dec eased om T1 o T2 only in he OR g oup (p=0.03), and
he change di e ed om he RESP g oup (OR −2.0 �2.4 mmol/L;
RESP 0.3 �1.6 mmol/L, p=0.02). In HRa g o HRpeak, he e we e
no signi ican changes in nei he o he subg oups, bu endencies
owa d dec emen om T1 o T2 in HRa g (p=0.07) and HRpeak
(p=0.06) we e ound in he OR. The RJ powe did no change in ime,
and no di e ence be ween he subg oups was obse ed. The abso-
lu e unning and jumping pe o mance es esul s a e p esen ed in
he Suppo ing In o ma ion S2, and indi idual esponses in 3000‐m
wi hin he subg oups a e p esen ed in Figu e 2. The body mass
emained unchanged h ough he s udy pe iod in he o al g oup o
pa icipan s and in bo h subg oups.
3.3
|
Hea a e and hea a e a iabili y in he
o hos a ic es and du ing sleep
The s anding HR dec eased om BL o OL2 (p=0.02), while he
noc u nal 4‐h HR dec eased only om BL o REC (p=0.02) in he o al
g oup o pa icipan s. In addi ion, he noc u nal 4‐h HRV inc eased
om BL o OL2 (p=0.04) and ended o emain inc eased a REC
(p=0.054). Subg oup analyses a e p esen ed in Figu e 3. The e was a
dec ease om BL o OL2 in he s anding HR o RESP (p=0.005), and
he change ended o be di e en compa ed o OR (p=0.054). In
addi ion, he noc u nal 4‐h HRV inc eased in RESP om BL o OL2
TABLE 2Weekly mean aining cha ac e is ics du ing he
baseline (BL), o e load (OL), and eco e y (REC) pe iods.
ALL (n=24) RESP (n=12) OR (n=8)
Volume (h)
BL 4.5 �1.0 4.4 �0.9 4.9 �1.3
OL 6.5 �1.3*** 6.4 �1.2*** 7.0 �1.7***
REC 2.7 �0.8** 2.6 �0.8*** 2.9 �0.9***
F equency (sessions/wk)
BL 4.3 �0.7 4.3 �0.7 4.7 �0.8
OL 5.4 �0.7*** 5.4 �0.6*** 5.6 �0.7***
REC 3.4 �0.6** 3.3 �0.5*** 3.5 �0.7***
Dis ance (km)
BL 43 �14 41 �12 50 �17
OL 65 �20*** 63 �18*** 73 �23***
REC 26 �8** 24 �6*** 29 �12***
HRz1/z2/z3 (%)
BL 89/8/4 88/8/3 91/6/3
OL 68/26/6*** 67/27/5*** 76/21/4***
REC 85/11/5* 83/12/4 88/8/4
Lucia's TRIMP
BL 310 �58 304 �50 328 �77
OL 533 �96*** 528 �95*** 535 �119***
REC 193 �51** 192 �61** 198 �49***
Session RPE
BL 1034 �206 1066 �185 1075 �2227
OL 2297 �623*** 2356 �584*** 2301 �623***
REC 711 �362*** 787 �484*** 666 �151***
No e: RESP = esponde s and OR =indi iduals wi h suspec ed
o e eaching. ***p<0.001, **p<0.01, and *p<0.05 compa ed o BL.
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(p=0.01), and he change di e ed compa ed o OR (p=0.011). The
noc u nal 4‐h HR did no change wi hin he g oups, bu he be ween‐
g oup change om BL o OL2 was di e en (p=0.002).
3.4
|
Changes in submaximal unning pe o mance,
con ol unning es , and CMJ
The HR‐ unning powe index inc eased in he o al g oup o pa ic-
ipan s om BL o OL2 (p<0.001) and REC (p=0.001). In he
subg oup analyses, HR‐ unning powe index inc eased om BL o
OL2 and REC only in RESP (p<0.001), and he change di e ed om
OR a OL2 (p=0.052) and REC (p=0.009).
The HR du ing he con ol unning es dec eased om BL o
OL2 a RPE 13 (p=0.001), RPE 17 (p<0.001), and du ing 6x3‐min
in e als (p<0.001) in he o al g oup o pa icipan s. The speed
emained unchanged a all RPE le els and du ing he 6x3‐min in-
e als ac oss he s udy pe iod. The e we e no signi ican di e ences
be ween he subg oups in any o he con ol es pa ame e s
(Figu e 4).
FIGURE 2 Indi idual esponses wi hin he subg oups. Whi e plo s e e o indi idual “ esponde s” (RESP) and g ay plo s “o e eached”
(OR) indi iduals.
FIGURE 3 Hea a e (HR) and HR a iabili y (LnRMSSD) in he o hos a ic es (A, B) and du ing sleep (C, D) in he esponde s (RESP) and
indi iduals wi h suspec ed o e eaching (OR). BL =baseline aining pe iod; OL =o e load aining pe iod; REC = eco e y pe iod. Dashed
ci cle indica es signi ican be ween‐g oup di e ence in he change om BL. **p<0.01 and *p<0.05 compa ed o he baseline (BL) alues.
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The CMJ ha was assessed wi hin he con ol sessions
dec eased om BL o OL1 (−5.9 �7.9%, p<0.01) and OL2
(−7.7 �8.7%, p=0.003) in he o al g oup o pa icipan s. The
dec ease om BL o OL2 was no signi ican in OR (−9.7 �11.0%,
p=0.105) o RESP (−7.4 �8.5%, p=0.082).
3.5
|
Subjec i e eco e y
Subjec i e eadiness o ain dec eased om BL o OL2 (p<0.001),
while so eness o he legs (p=0.04) and a igue o he leg muscles
inc eased (p<0.001) a OL2 compa ed o BL in he o al g oup o
pa icipan s. All subjec i e a iables e u ned o baseline a REC and
we e no di e en compa ed o BL. The changes in subjec i e e-
co e y wi hin he subg oups a e p esen ed in Figu e 5. Al hough
subjec i e eadiness o ain dec eased om BL o OL2 in OR
(p<0.001) and RESP (p=0.004), he changes we e g ea e in OR
compa ed o RESP (p=0.009). Simila ly, he change in so eness o
he legs om BL o OL2 di e ed be ween he subg oups (p=0.04).
The exe cise pe cep ion dec eased om BL o OL2 only in he OR
g oup (p=0.009) and he change di e ed om RESP (p=0.02).
Subjec i e sleep, a igue, and s ess emained una ec ed compa ed
o BL du ing OL1 and OL2 in he o al g oup and subg oups o he
pa icipan s.
3.6
|
Disc imina ion o OR and RESP indi iduals
The a iables wi h he mos signi ican esul s in he ROC analyses
a e p esen ed in Figu e 6, and hei 7‐day olling a e age esponses
ac oss he OL a e p o ided in he Suppo ing In o ma ion S3. In
addi ion o he a iables p esen ed in he igu es, he AUC o supine
HR (0.821, cu ‐o 0.80%, p=0.006), noc u nal ull HR (0.845, cu ‐o
0.68%, p=0.001), and noc u nal ull LnRMSSD (0.738, cu ‐o 2.23%,
p=0.038) we e signi ican .
When OL‐induced esponses o moni o ing a iables we e
compa ed be ween he subg oups, changes in HR‐ unning powe
index s a ed o di e a e 6 days, in noc u nal 4‐h HR a e 9 days,
and in noc u nal 4‐h HRV a e 10 days o OL. Among he subjec i e
ma ke s, changes in eadiness o ain s a ed o di e on he 11 h
day, while so eness o he legs and exe cise pe cep ion di e ed only
on he 14 h day o OL. The mos alid a iables o disc imina e be-
ween OR and RESP indi iduals a he end o he OL we e noc u nal
HR, eadiness o ain, and HR‐ unning powe index, all ha ing ≥85%
FIGURE 4 Speed and ela i e hea a e (HR) du ing he a ing o pe cei ed exe ion (RPE)‐based submaximal unning es and he
ollowing 6x3‐min in e al session which was pe o med a maximal sus ainable e o . BL =baseline aining pe iod; OL =o e load aining
pe iod; REC = eco e y pe iod; RESP = esponde s; and OR =indi iduals wi h suspec ed o e eaching. *p<0.05 compa ed o he baseline
(BL) alues.
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