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Overtraining in Resistance Exercise: An Exploratory Systematic Review and Methodological Appraisal of the Literature


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Background The balance between training stress and recovery is important for inducing adaptations to improve athletic performance. However, continuously high training loads with insufficient recovery may cause fatigue to accumulate and result in overtraining. A comprehensive systematic review is required to collate overtraining literature and improve the current understanding of the mechanisms underlying functional overreaching (FOR), non-functional overreaching (NFOR) and the overtraining syndrome (OTS) in resistance training. Objective The objective of this systematic review was to establish markers of overtraining and elucidate the mechanisms underlying maladaptive resistance training conditions. Furthermore, this review aims to critically evaluate the methodological approaches of the overtraining literature. Methods A systematic literature search was performed on PubMed, Web of Science and SPORTDiscus to identify studies up to June 2019. Electronic databases were searched using terms related to resistance training and overtraining. Records were included if they attempted to induce a state of overreaching or overtraining through resistance exercise in healthy participants. Results A total of 22 studies were selected for review. Among these studies, eight resulted in decrements in performance and measured changes in performance during a follow-up period. There were four studies that reported decrease in performance yet failed to implement follow-up measures. A total of 10 studies reported no decline in performance. Overall, a lack of standardisation in methodology (follow-up performance testing) and diagnostic criteria prevents consistent determination of FOR, NFOR and OTS in resistance training. Conclusions Few studies have appropriately established FOR, NFOR or OTS in resistance training. Overtraining may be related to frequent high-intensity and monotonous resistance training. However, no marker other than a sustained decrease in performance has been established as a reliable indicator of overtraining in resistance exercise. Registration This systematic review was registered on the Open Science Framework ( (
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Sports Medicine
Overtraining inResistance Exercise: AnExploratory Systematic Review
andMethodological Appraisal oftheLiterature
ClementineGrandou1 · LeeWallace1· FrancoM.Impellizzeri1· NicholasG.Allen1· AaronJ.Coutts1
© Springer Nature Switzerland AG 2019
Background The balance between training stress and recovery is important for inducing adaptations to improve athletic per-
formance. However, continuously high training loads with insufficient recovery may cause fatigue to accumulate and result
in overtraining. A comprehensive systematic review is required to collate overtraining literature and improve the current
understanding of the mechanisms underlying functional overreaching (FOR), non-functional overreaching (NFOR) and the
overtraining syndrome (OTS) in resistance training.
Objective The objective of this systematic review was to establish markers of overtraining and elucidate the mechanisms
underlying maladaptive resistance training conditions. Furthermore, this review aims to critically evaluate the methodologi-
cal approaches of the overtraining literature.
Methods A systematic literature search was performed on PubMed, Web of Science and SPORTDiscus to identify studies up
to June 2019. Electronic databases were searched using terms related to resistance training and overtraining. Records were
included if they attempted to induce a state of overreaching or overtraining through resistance exercise in healthy participants.
Results A total of 22 studies were selected for review. Among these studies, eight resulted in decrements in performance and
measured changes in performance during a follow-up period. There were four studies that reported decrease in performance
yet failed to implement follow-up measures. A total of 10 studies reported no decline in performance. Overall, a lack of
standardisation in methodology (follow-up performance testing) and diagnostic criteria prevents consistent determination
of FOR, NFOR and OTS in resistance training.
Conclusions Few studies have appropriately established FOR, NFOR or OTS in resistance training. Overtraining may be
related to frequent high-intensity and monotonous resistance training. However, no marker other than a sustained decrease
in performance has been established as a reliable indicator of overtraining in resistance exercise.
Registration This systematic review was registered on the Open Science Framework (https :// (https ://
/ ).
Electronic supplementary material The online version of this
article (https :// 9-019-01242 -2) contains
supplementary material, which is available to authorized users.
* Clementine Grandou
1 Human Performance Research Centre, University
ofTechnology Sydney, Sydney, Australia
1 Introduction
Many athletes perform resistance exercise or strength train-
ing as a means to improve athletic performance. Resistance
training programs can be systematically manipulated through
changes in training variables (i.e. intensity, volume, exercise
selection and sequence, rest intervals, repetition velocity and
training frequency) to elicit a specific response (i.e. muscular
strength, hypertrophy, endurance, motor performance, bal-
ance or coordination) [1, 2]. Strenuous resistance training
loads should be applied to obtain high-level performance
in strength and power-based sports [2]. The physical per-
formance of an athlete undertaking resistance training may
be influenced by their ability to adapt to increasing training
loads. Consequently, athletes and coaches are continually
challenged to find the optimal balance between training and
recovery to enhance athletic performance. A disruption in
this balance may result in impaired performance [3, 4].
During a typical training cycle, athletes often undergo
periods of overload and recovery in an attempt to optimise
physical performance. The process of overload is achieved
through an increase in training load [3]. Acute fatigue
occurs following overload training which may result in a
C.Grandou et al.
Key Points
Failure to demonstrate decreases in performance and
inadequate performance testing during a follow-up
period prohibit the diagnosis of FOR, NFOR or OTS in
the majority of studies.
Early studies show that frequent and monotonous resist-
ance training performed at high intensity may increase
susceptibility to training maladaptation.
The mechanisms that underlie overtraining in resistance
exercise remain unclear. Coaches and athletes must con-
tinue to rely on training-specific performance decrements
to determine FOR, NFOR or OTS.
longer-term decrements in performance with or without
a range of other symptoms (e.g. hormonal dysregulation,
psychological disturbances, reduced immune function, sleep
disorders) that require ‘weeks-months’ and ‘months-…’ to
recover, respectively [7]. Consequently, the correct diagnosis
requires maximal performance testing and can only be made
retrospectively. Importantly, the OTS is characterised by an
unexplained decline in performance and depends on a wide
variety of training and contextual factors. Therefore, the cor-
rect diagnosis of OTS should also be based on the exclusion
of confounding factors/disorders (e.g. viral disorder, bacte-
rial infection and other physical diseases) [7]. The amount
that performance must deteriorate before FOR, NFOR or
OTS is diagnosed has been debated in the literature. The
magnitude of performance decline required to diagnose
FOR, NFOR or OTS may vary widely depending on the
specific performance assessment and the training status of
the athlete. Despite the fact that a meaningful decrease in
sport-specific performance is individual, for the purpose of
this review, a statistically significant decline in performance
was necessary to indicate a state of possible FOR, NFOR
or OTS.
The majority of previous overreaching/overtraining inves-
tigations have been conducted in endurance activities [7].
However, previous authors have proposed that overtrain-
ing in resistance exercise can elicit considerably different
biological responses when compared to overtraining with
endurance activities [8, 9]. The mechanisms behind these
contrasting responses have not been established. Accord-
ingly, there is a need to investigate overtraining respective to
the training mode. It has also been suggested that the aetiol-
ogy of resistance exercise overtraining differs with regard
to whether training volume or intensity is manipulated/
increased [7]. However, the mechanisms and manifestation
of FOR, NFOR and OTS through resistance exercise remain
relatively unknown.
Overtraining has been suggested to be a significant prob-
lem for strength or power athletes who undertake primar-
ily resistance training [8]. Determining the point at which
training becomes maladaptive continues to challenge both
athletes and coaches in their attempts to achieve optimal
performance. At present, there is no systematic review of
the studies that have examined NFOR, FOR or OTS in
resistance-trained athletes. Therefore, the purpose of this
systematic review was to critique and appraise the results
and methodology of studies that have attempted to induce
FOR, NFOR or OTS through resistance exercise in healthy
adults. Additionally, the present review aims to elucidate the
physiological alterations and potential mechanisms of over-
training, as well as determine if any markers (performance,
biochemical, physiological or psychological) may be used to
monitor FOR, NFOR or OTS in resistance training.
temporary performance decrement [5]. When adequate rest
is prescribed, the resultant acute fatigue may be followed
by a positive adaptation or improvement in performance
[3]. This process is referred to as functional overreaching
(FOR). It is well established that periods of physiological
stress are required to stimulate the adaptations responsible
for enhancing performance [3]. Accordingly, coaches and
athletes often induce FOR as part of a training program to
elicit a supercompensation effect. However, continuously
high training loads with insufficient recovery may cause
fatigue to accumulate and result in long-term reductions in
performance capacity. This maladaptation to training can
manifest as a state of non-functional overreaching (NFOR)
and, in extreme and prolonged cases, may develop into the
overtraining syndrome (OTS).
Many previous studies have investigated the mechanisms
of overtraining in an attempt to establish indicators of over-
training through the use of various performance, biochemi-
cal, physiological and psychological parameters (for review,
see Halson etal. [6] and Meeusen et al. [7]). However,
despite many attempts, no clear guidelines or diagnostic
tools other than a sustained decrease in performance have
emerged for the monitoring and detection of FOR, NFOR or
OTS in resistance exercise [7]. This may be due to the varied
terminology used by previous studies or the difficulty that
lies in differentiating between these conditions. This review
follows the well-accepted definitions proposed by Meeusen
etal. [7], where FOR, NFOR and OTS are differentiated by
the length of time required for recovery. FOR is defined as
a short-term decrement in performance without severe psy-
chological or other lasting negative symptoms that requires
‘days-weeks’ to recover. FOR is followed by a subsequent
supercompensation effect where performance is improved.
NFOR and OTS are caused by overtraining and defined as
Overtraining in Resistance Exercise…
2 Methods
This review was conducted according to PRISMA (Preferred
Reporting Items for Systematic Reviews and Meta-Analyses)
guidelines [10]. A systematic review protocol that included
the review question, search strategy, exclusion criteria and
risk of bias assessment was registered with the Open Science
Framework (10.17,605/OSF.IO/5BMSP; 11 January 2019).
2.1 Eligibility Criteria
Eligibility criteria were drafted and subsequently refined
by three authors (CG, LW, FI) using a random sample of
studies. Included studies met the following study crite-
ria [population, intervention, comparator, outcome, study
design (PICOS)] and report characteristics. P: Participants
with chronic diseases, metabolic disorders or musculoskel-
etal injuries were excluded. Studies were considered eligi-
ble if they included an intervention aimed to induce FOR,
NFOR or OTS through resistance training. I: Interventions
were included regardless of whether or not they were able to
induce a decrement in performance which is essential for the
diagnosis of FOR, NFOR or OTS. Studies involving an acute
bout of intensified training (i.e. increased training load) were
not eligible for inclusion in this review unless the authors
stated that they were attempting to overreach or overtrain
participants. Interventions combining resistance training
and aerobic training were excluded to account for a possible
interference effect. Supplementation studies were eligible
for inclusion if the data provided for non-supplemented par-
ticipants were reported separately. C: All comparators and
control conditions were eligible for this review. O: Changes
in physical performance following the overtraining period
and follow-up were the primary outcome measure of this
review. Secondary outcome measures included biochemical,
neuro-muscular, psychological and morphologic effects. S:
This review considered randomised controlled trials (RCTs),
non-randomised controlled trials (NRCTs), uncontrolled tri-
als (UCTs) and grey literature to ensure literature saturation.
2.2 Search
A literature search was conducted by one author (CG) in
the following electronic databases: PubMed, Web of Sci-
ence Core Collection and SPORTDiscus. Databases were
searched from inception up until June 2019. No language or
publication status restrictions were imposed on the search to
ensure literature saturation. The following Boolean search
string was used on all databases: (resistance training OR
resistance exercise OR strength training OR strength exer-
cise OR weight training OR weight exercise OR weight
lifting OR weightlifting) AND (overtrain* OR over-train*
OR overreach* OR over-reach* OR fatigue OR underper-
formance OR underperformance OR under performance OR
underrecovery OR under-recovery OR under recovery). A
comprehensive search strategy is provided in TableS1. Trial/
study registries were searched during a pilot phase; how-
ever, due to the non-clinical nature of this review no results
were found. In conjunction with the database searches, the
reference lists of relevant studies, reviews and books were
screened for possible omissions.
2.3 Study Selection
Articles retrieved through the systematic search were
exported into a reference management software (EndNote
version X8) and all duplicate articles were removed. All
references were then imported into Covidence (Covidence
Systematic Review Software, Veritas Health Innovation,
2013) for assessment of eligibility. Two authors (CG, NA)
independently screened the records by title and abstract,
with all potentially eligible references proceeding to full-
text screening; conflicts were resolved by a third author (FI).
Two authors (CG, NA) then independently screened the full
text of all included articles against the eligibility criteria.
2.4 Data Extraction
Data were extracted by two authors (CG, LW) and imported
into an Excel spreadsheet that was designed for this review
(TableS2). Information extracted from each eligible study
included publication details (author, year), participant char-
acteristics (sex, training history), study methods (design,
randomisation), overtraining intervention (duration, mode,
frequency, volume, intensity, length of follow-up) and com-
parator. Additionally, pre- and post-intervention values were
extracted for primary (physical performance) and second-
ary (biochemical, physiological and psychological) outcome
2.5 Risk ofBias Assessment
The results between the groups were not of interest for this
review; rather the pre-to-post changes were required for
assessment of the effects of overtraining. Accordingly, an
assessment of bias was undertaken of relevant methodologi-
cal variables. To comply with the AMSTAR 2 (Assessing
the Methodological Quality of Systematic Reviews), assess-
ment of allocation concealment, blinding of participants and
assessors was conducted for RCTs. Additionally, confound-
ing and selection bias were assessed for NRCTs and UCTs.
Furthermore, risk of bias assessment included a narrative
review of the length of follow-up and frequency of perfor-
mance testing that is required to accurately diagnose a state
C.Grandou et al.
of FOR, NOR or OTS. The proposed methods of assessment
of risk of bias were changed from the review protocol reg-
istered on the Open Science Framework. One author (CG)
piloted the proposed method of using the Cochrane risk of
bias appraisal tool for the included RCTs. However, due
to the nature of this review, the results did not accurately
reflect risk of bias in terms of overtraining methodology. For
example, if the performance of participants was not assessed
during a follow-up period, there would be an inherent risk
of bias within the results as an accurate diagnosis of FOR,
NFOR or OTS cannot be made.
3 Results
3.1 Study Selection
The initial database search yielded 4649 studies. An addi-
tional nine studies were identified through other sources
(searching reference lists and consultation with experts)
(Fig.1). Once duplicates were removed, 2992 titles and
abstracts were screened for inclusion and of those 2923 stud-
ies were excluded based on the eligibility criteria (Sect.2.1).
A total of 69 studies were retrieved as full text and assessed
for eligibility and of those 47 were excluded (TableS3).
The reasons for exclusion at the full text level are displayed
in Fig.1. Upon completion of these procedures, 22 studies
were included for analysis in this systematic review.
3.2 Study Characteristics
Among the 22 included studies, 14 were RCTs, 2 were
NRCTs, and 6 were UCTs. Physical performance of par-
ticipants was measured by 20 of the included studies. Fry
etal. [11, 12] reported on secondary outcomes of a previous
study by the same author which did include physical per-
formance measures [13]. However, these studies are treated
separately throughout this review. At least, one measure of
performance significantly declined following the overload
program of 12 studies (Fig.2) [9, 1121]. Within the stud-
ies that reported a decline in a measure of physical perfor-
mance, eight included follow-up measures after the overload
training intervention [1113, 1620]. No decline in physi-
cal performance was reported in ten of the included stud-
ies [2231]. Lowery etal. [27] did not presentperformance
data for placebo participantsand therefore was included in
studies that did not induce a decline in performance. Addi-
tionally, authors should exercise caution when interpreting
the results of Lowery etal. [27] and Wilson etal. [31] due
to the controversy surrounding these manuscripts [32]. The
descriptive results of the 12 studies that reported decreases
in performance are displayed in Table1. The descriptive
47 full-text articles excluded:
Concurrent aerobic exercise (n =15)
No attempttooverreach/overtrain (n =13)
No intervention (n = 11)
Unable to retrieve (n = 4)
Conference abstract (n = 3)
Injury (n = 1)
4649 records identified through database
9additional records identified through
other sources
2992 records after duplicates removed
2992 records screened
69 full-text articles assessed for eligibility
2923 records excluded
22 studies included in systematic review
Fig. 1 PRISMA flow diagram of systematic search and included studies
Overtraining in Resistance Exercise…
results of the nine studies that did not adversely affect per-
formance are displayed in the TableS4. Among the 12 stud-
ies that reported decreases in performance, nine reported
on measures of biochemistry [1113, 1518, 20, 21], five
studies investigated physiological changes [13, 16, 1820],
and three studies measured psychological and perceptual
responses [9, 13, 18].
3.3 Performance
Twelve studies demonstrated decreases in at least one meas-
ure of performance following an overload training interven-
tion (Table2). Among these studies, eight implemented
follow-up measures of performance. The majority of studies
reported that performance was restored within the follow-
up period. However, many studies failed to report the time
course changes of performance within the follow-up period
[9, 14, 15, 21]. The most common performance measure
was maximal muscular strength. Six studies demonstrated
significant decreases in strength [1113, 1618]. Contrasting
results were found for secondary performance measures. For
example, six studies measured vertical jump performance
[9, 1416, 18, 21], of these, three resulted in decreased per-
formance [15, 18, 21]. Additionally, two studies reported
decrements in sprint performance [9, 14]. Fry etal. [14]
reported decreases in sprint performance; however, 1RM
strength improved following the training intervention. Other
secondary performance measures included in the analyses
Follow-up measures (n=8)
Duration: >1 month (n=5)
•Fry et al. [13] (survey)
•Fry et al. [12] (survey)
•Fry et al. [11] (survey)
•Fry et al. [16] (interview)
•Margonis et al. [18]
Duration: <1 week (n=1)
•Hecksteden et al. [17]
Decrease in one measure of
physical performance (n=12)
Duration: 1 week –1 month
•Nicoll et al. [19]
•Sterczala et al. [20]
No decrease in any measure
of physical performance
•Fry et al. [24]
•Fahey et al. [22]
•Raastad et al. [28]
•Ratamess et al. [29]
•Fatouros et al. [23]
•Kraemer et al. [26]
•Sweeny et al. [30]
•Wilson et al. [31]
•Hasegawa et al. [25]
•Lowery et al. [27]
Included studies (n=22)
No follow-up measures (n=4)
•Warren et al. [21]
•Fry et al. [15]
•Fry et al. [14]
•Fry et al. [9]
Fig. 2 Flow diagram of performance outcomes and follow-up interventions of included studies
C.Grandou et al.
Table 1 Descriptive results of studies that adversely affected at least one measure of physical performance
Study design Study Subjects Overload training Follow-up
Duration Frequency Volume and intensity
(sets × repetitions)
RCT Fry etal. [13] 17 resistance trained, men 2weeks OT: 7days/week
C: 1day/week
OT: 10×1 at 100% 1RM
C: 3 ×5 at 50% 1RM
Tru-Squat machine
(upper body resistance
exercise held constant)
Follow up survey (8
RCT Fry etal. [12] [13] [13] [13] [13] [13] [13]
RCT Fry etal. [11] [13] [13] [13] [13] [13] [13]
RCT Fry etal. [16] 16 resistance trained, men 2weeks OT: 7days/week
C: 2days/week
OT: 10×1 at 100% 1RM
C: 3×5 @ 50% 1 RM
Tru-Squat machine Follow up interviews
UCT Margonis etal. [18] 12 recreationally trained,
3weeks 6days/week 6 ×1–6 at 85–100% 1RM Bench press, squat,
snatch, hang clean,
deadlift, curl and row
3weeks, 2days/week:
2× 10–12 at 70% 1RM
Then 3weeks rest
UCT Nicoll etal. [19] 14 resistance trained, men
HPOR (n = 6)
HIOT (n = 8)
HIOT: [16]
HPOR: 2 sessions/day
HIOT: [16]
HPOR: 10×5 at 70%
1RM (maximum con-
centric velocity)
HIOT: [16]
HPOR: barbell back squat
HIOT: [16]
HPOR: 1-week recovery
HIOT: [16]
RCT Sterczala etal. [20] 17 resistance trained, men
AA (n = 8)
Placebo (OT) (n = 3)
Control (n = 6)
1week AA/OT: 15 sessions
C: maintained normal
training schedule
AA/OT: 10×5 at 70% of
the system 1RM mass.
When barbell velocity
dropped below 90% of
the highest value for the
set load was reduced.
C: maintained normal
training schedule
AA/OT: ‘speed’ barbell
back squats
C: maintained normal
training schedule
1week training cessation
UCT Hecksteden etal. [17] 23 strength athletes, men
and women
6days 11 sessions 4×6 at 85% 1RM
Implementing drop sets
to failure and eccentric
overload training
Bench press and squat
(plus variations)
2days rest
No follow-up
UCT Warren etal. [21] 28 elite junior weightlift-
7days 2–3 sessions/day Approximate volume:
Intensity: percentage of
the participants best
snatch and best clean
and jerk
Snatch, clean, back squat,
front squat, snatch pull
and clean pull
Overtraining in Resistance Exercise…
Table 1 (continued)
Study design Study Subjects Overload training Follow-up
Duration Frequency Volume and intensity
(sets × repetitions)
RCT Fry etal. [15] 28 male weightlifters
AA (n = 13)
Placebo (n = 15)
7days 2–3 sessions/day Approximate volume:
Intensity: 70–100% 1RM
Multi-joint barbell
exercises: snatch, power
snatch, snatch pull,
clean, power clean,
clean pull, jerk, push
jerk, push press, clean
and jerk, front squat,
back squat
RCT Fry etal. [14] 9 resistance trained, men 3weeks OT: 5days/week
C: 2days/week
OT: 8×1 at 95% 1RM
C: 3×5 at 70% body
Tru-Squat machine
NRCT Fry etal. [9] 6 resistance trained, men 3weeks 3days/week Barbell back squat:
2×1 at 95% 1 RM
3×1 at 90% 1RM
Leg curls:
Barbell back squat and
leg curls
(upper body resistance
exercise held constant)
RCT randomised controlled trial, UCT uncontrolled trial, RM repetition maximum, OT overload training, C control, NR not reported, HMB-FA beta-hydroxy-beta-methylbutyrate-free acid, AA
amino acid, HPOR high power overreaching, HIOT high-intensity overtraining, kg kilogram
C.Grandou et al.
were maximal repetitions until exhaustion [13, 15, 21], Win-
gate power [18], sit and reach [9], and muscular torque [13,
3.4 Biochemistry
Biochemical responses were reported by nine studies that
demonstrated decreases in performance. A variety of blood
and urinary biomarkers including hormones and muscle
damage markers as well as oxidative stress and inflamma-
tory markers were reported. Four studies reported on the
between-group biochemical responses of overload partici-
pants in comparison to a control (Table3). Additionally, nine
studies provided pre- to post-intervention results for over-
load training participants (TableS5). Commonly reported
measures included cortisol [11, 15, 20], testosterone/free
Table 2 Performance results of studies that adversely affected at least one measure of physical performance
RCT randomised controlled trial, NRCT non-randomised controlled trial, UCT uncontrolled trial, HPOR high power overreaching, HIOT high-
intensity overtraining, RM repetition maximum, CMJ countermovement jump
Study Study design Performance post overload training Follow-up
Improved No change Declined
Fry etal. [13] RCT Squat repetitions @ 70%
1RM squat
Isokinetic leg extension
Follow-up survey indicated
that participants were able
to return to normal training
load with 2–8weeks of
Fry etal. [12] RCT [13] [13] [13]
Fry etal. [11] RCT [13] [13] [13]
Fry etal. [16] RCT Vertical jump (CMJ, squat
jump, depth jump)
Mean power, peak velocity
and peak force @ 40,
70% 1RM
1RM squat
Mean power @ 100% 1RM
Follow-up interviews
indicated that participants
were able to return to
normal training load with
2–8weeks of recovery.
Margonis etal. [18] UCT 1RM strength
Vertical jump
Wingate power
1RM strength returned to
baseline values following
3weeks of recovery.
Nicoll etal. [19] UCT HIOT: [16] HPOR: squat mean power
HIOT: [16]
HPOR: muscular power
returned to baseline fol-
lowing 1week of recovery.
HIOT: [16]
Sterczala etal. [20] RCT 1RM back squat
Squat mean power @70%
Squat mean barbell veloc-
ity @ 70% 1RM
Mean barbell velocity values
returned to baseline fol-
lowing 1week of training
Hecksteden etal. [17] UCT Squat maximal isometric
Bench press maximal
isometric contraction
Performance was not
restored to baseline values
following 2days rest
Warren etal. [21] UCT Snatch lift test to exhaus-
Vertical jump
Fry etal. [15] Snatch (repetitions, missed
lifts & successful lifts)
Vertical jump
Fry etal. [14] RCT 1RM squat
Agility run (left)
Isokinetic leg extension
Agility run (right)
Vertical jump (CMJ, non-
CMJ, low depth, high
Fry etal. [9] UCT 1RM squat
Sit and reach
Lower body reaction time
Vertical jump
Back and hip extension
isokinetic peak force
Squat isokinetic peak force
Overtraining in Resistance Exercise…
testosterone [11, 15, 20], testosterone:cortisol (T:C) ratio/
free T:C ratio [11, 15, 20], basal growth hormone [11, 15,
17] and exercise induced growth hormone [11, 15], catecho-
lamines [12, 16, 20], creatine kinase (CK) [13, 17] and pre-
and post-exercise blood lactate/lactic acid [12, 13, 15, 21].
In comparison to a control, overload training participants
demonstrated exacerbated responses of cortisol [20], cre-
atine kinase [13] and noradrenaline [12]. Blunted responses
were reported in T:C and free T:C ratio [11] and exercise-
induced lactate concentrations [13].
3.5 Physiology
Amongst the studies that demonstrated declines in perfor-
mance, five measured physiological adaptations. For exam-
ple, Fry etal. [13] reported no significant changes in resting
heart rate upon waking. Decreases in range of motion were
demonstrated following 3weeks of overload resistance train-
ing [18]. Three studies investigated the physiological mecha-
nisms that may underpin the decline in performance charac-
teristic of overtraining [16, 19, 20]. No significant changes
were demonstrated in contractile protein isoform expression
[16, 19]. Fry etal. [16] and Sterczala etal. [20] reported
downregulation of the β2-adrenergic receptor (β2-AR) system
with simultaneous increases in epinephrine:β2-AR density
following overload training. Additionally, Nicoll etal. [19]
reported altered mitogen-activated protein kinase (MAPK)
activity in response to overtraining in resistance exercise.
3.6 Psychological andPerceptual Responses
Psychological and perceptual responses were reported by
three studies that demonstrated declines in performance.
Margonis etal. [18] demonstrated increases in delayed
onset muscle soreness following the increase in training
load. Conflicting results were reported for perceived lower
back pain and knee pain. No increases in pain were reported
where participants trained 3days per week [9]. However,
increases in pain were demonstrated in a study where par-
ticipants trained 7days per week [13]. Fry etal. [13] also
reported decreases in perceived recovery and strength status
following the overload training intervention. However, no
significant changes in sleep pattern (sleep quality and dura-
tion) were reported throughout the trial [13].
3.7 Risk ofBias
The risk of bias assessment results, including selection
bias, performance bias and confounding bias, is available in
Fig.S6. In the case of UCTs, selection bias was assessed as
not applicable as study protocol did not involve allocation
of participants. No studies demonstrated adequate allocation
concealment. Random sequence generation was performed
by one study [31]. Blinding of participants was adequately
performed by seven studies [15, 20, 22, 2628, 31]. How-
ever, as these studies involved supplementation groups, only
the results of the placebo participants are relevant for discus-
sion in this review. A total of eight studies are reflective of
possible FOR, NFOR or OTS [1113, 1620]. These studies
demonstrated an adequate decrease in at least one meas-
ure of performance and included follow-up measures after
the overload period. Of these studies, only one adequately
controlled for nutritional confounders [18]. An additional
bias may exist as the majority of the studies included in this
review came from the same group of authors.
4 Discussion
Despite the fact that many athletes perform resistance-based
exercise as a significant part of their training, much of the
scientific literature on overtraining has focused on endurance
activities [7]. This review analysed changes and attempted
to identify relationships between numerous measures of
performance, biochemistry, physiology and psychology that
occurred in response to FOR, NFOR or OTS in resistance
exercise. This systematic review also aimed to develop an
understanding of the mechanisms and manifestation of over-
training in resistance exercise. Such findings may provide
Table 3 Between-group biochemical responses of overload partici-
pants in comparison to control participant following the completion
of overload training
T:C testosterone:cortisol, β2-AR β2-adrenergic receptor, R resting, EI
exercise induced
Parameter Measure Blunted
No signifi-
cant differ-
Cortisol R [20]
Testosterone R [20]
T:C ratio R [11] [20]
EI [11, 20]
Free T:C ratio R [11]
EI [11]
Adrenaline R [12, 20]
EI [12]
Noradrenaline R [12]
EI [12]
Adrenaline: β2-AR
R [20]
Blood biomarkers and muscle damage
Lactate R [13]
EI [13]
Creatine kinase R [13]
C.Grandou et al.
an early indication of training maladaptation. However, to
accurately elucidate the effects of overtraining in resistance
exercise, it is important to accurately diagnosis a state of
FOR, NFOR or OTS in intervention participants.
4.1 Summary ofEvidence
4.1.1 Establishing Overreaching/Overtraining
Previous studies have attempted to investigate the time
course changes of training maladaptation in resistance exer-
cise. However, many investigations have failed to appropri-
ately induce and diagnose FOR, NFOR or OTS. Methodo-
logical limitations and contrasting definitions within the
literature contribute to the discrepant findings. At present,
changes in performance and recovery time are required
to diagnose and distinguish between these conditions [7].
Amongst the 22 studies included in this review, only eight
studies reported declines in performance and implemented
follow-up measures. However, few studies used a longitu-
dinal approach to monitor performance during a follow-up/
recovery period. Due to the short duration and lack of per-
formance testing throughout the follow-up period, the time
course changes of performance in much of the resistance
exercise overtraining literature remain unknown. Addition-
ally, many studies that adversely affected performance did
not measure performance during a follow-up period. Whilst
these studies may provide some insight into training mal-
adaptation, it is not possible to determine the prognosis of
training maladaptation if performance is not adequately
monitored throughout a follow-up period.
Many of the previous resistance overtraining interven-
tions failed to adversely affect performance following an
overload training period. Whilst these studies are not reflec-
tive of a state of FOR, NFOR or OTS, many researchers
reported that overreaching or overtraining occurred. For
example, Raastad etal. [28] did not report any decreases
in performance measures (i.e. muscular strength), yet sug-
gested that this should be recognised as overreaching as the
strength gain per workout was reduced. However, a decline
in strength adaptation per training bout may simply reflect
the law of diminishing returns rather than a maladaptation
to training. Future studies should attempt to standardise
methodology (e.g. follow-up period and performance test-
ing) and diagnostic criteria (e.g. demonstrated decrease in
performance lasting ‘days-weeks’ for FOR, ‘weeks-months’
for NFOR and ‘months…’ for OTS) to avoid inappropri-
ate determination of FOR, NFOR and OTS in resistance
4.1.2 Performance
Performance outcomes of resistance training have been
measured using a number of different tests including maxi-
mal muscular strength, muscular torque, force produc-
tion and maximal repetitions until exhaustion [9, 16, 21].
To establish training maladaptation, the performance test
utilised should be a reflection of an athlete’s competition
performance [7]. However, there is a lack of consistency
in performance measures implemented within studies. This
may be due to the diverse nature of resistance training and
the variety of athletic performance outcomes (e.g. maximal
strength, muscular power or hypertrophy). If the perfor-
mance outcome of a resistance-based sport/discipline is not
maximal strength, it is counterintuitive to measure maxi-
mal strength as a primary performance indicator. Therefore,
future studies utilising resistance training must specify a pri-
mary performance test reflective of the demands and envi-
ronmental context of an athlete’s competition performance.
The most common methods for assessing performance in
included studies are maximal muscular strength tests. Maxi-
mal muscular strength tests are a resistance training-specific
tool that can be utilised for the detection of FOR, NFOR or
OTS in resistance exercise. However, maximal strength tests
are exhaustive in nature and may contribute to fatigue levels
which increase the risk of training maladaptation. Few stud-
ies demonstrated decreases in maximal strength. For exam-
ple, Margonis etal. [18] reported significant decreases in
1RM strength which were not restored following a 6-week
taper period. These results suggest that athletes developed
the OTS. Hecksteden etal. [17] reported a significant decline
in maximal isometric force that did not return to normal val-
ues following a recovery period of 2days. However, due to
the short follow-up period the length of recovery required to
distinguish between FOR, NFOR or OTS, correct diagnosis
is not possible. Additional studies that reported decreases in
maximal strength utilised participant interviews and surveys
to monitor the length of recovery required to re-establish
performance [1113, 16]. Collectively, these studies have
reported attenuated performance which may provide impor-
tant insight into the mechanisms and manifestation of train-
ing maladaptation. However, as these studies did not appro-
priately measure performance during a sufficient follow-up
period it is not possible to determine if these results reflect
FOR, NFOR or OTS. Future research should implement
follow-up measures to assess the time course changes of
performance to appropriately diagnose FOR, NFOR or OTS.
The lack of longitudinal interventions which have dem-
onstrated training maladaptation presents difficulties in the
attempt to monitor and diagnose overtraining. It appears as
though maximal muscular strength is resilient to large acute
increases in training load. Therefore, secondary performance
measures may be useful for the early detection of FOR,
Overtraining in Resistance Exercise…
NFOR or OTS in resistance-trained athletes. Previous stud-
ies have employed a variety of performance measures (e.g.
sprint time, vertical jump height) not specific to the resist-
ance training protocol that may provide important insight
into the monitoring of possible overtraining [1416, 21].
Contrasting results were reported for secondary performance
measures. Collectively, it appears as though changes in max-
imal strength may not reflect performance in other tasks.
Future studies should aim to appropriately establish FOR,
NFOR or OTS and determine whether such tests could be
used to monitor the manifestation of these conditions. Per-
formance testing is an efficient and inexpensive method to
monitor and prevent overtraining. However, given the short
duration and wide variety of performance measures used by
many studies, there remains insufficient evidence to reach
a consensus on performance tests that monitor overtraining
in resistance exercise.
The majority of the literature on overtraining in resistance
exercise has been reported following interventions where
physical performance was not adversely affected. Although it
is difficult to compare without consistent measures between
studies, differences in the prescription of overload training
protocols may provide insight into the type of resistance
training that may increase susceptibility to overtraining. The
training frequency and relative training intensity of interven-
tions that did induce performance decrements appear to be
higher than those that did not adversely affect performance.
All studies that performed multiple sets of one repetition at
high intensity (e.g. 10 sets × 1 repetition at 100% 1RM, every
day for 2weeks) were able to induce performance decreases
[1113, 16]. Low volume, high-intensity and -frequency
protocols such as those used in these interventions may be
insightful for research purposes. However, coaches and ath-
letes are unlikely to implement such regimes as part of a
training program due to the risk of injury associated with
training at maximal loads [33]. Previous studies that dem-
onstrated no adverse effects on performance implemented
training protocols that are likely more reflective of how
resistance-based athletes would normally train. However,
as many overtraining studies have been unable to induce
FOR, NFOR or OTS and the concomitant performance
decrements, the trade-off between ecological validity and
adequate manipulation of exercise volume and/or intensity
to elicit a maladaptive response must be considered. These
studies may still provide important insight into resistance
exercise FOR, NFOR and OTS.
Training monotony may be expressed as the amount of
variation in training load within one training cycle [34].
A previous study has suggested that monotonous training
increases susceptibility to overreaching and overtraining in
endurance activities [35]. Although there is little empiri-
cal evidence examining the relationship between training
monotony and overtraining, it appears as through monotony
of training load may increase the likelihood of overtraining
in resistance exercise. Many previous studies that reported
performance decrements utilised interventions where only
one type of resistance exercise was performed (i.e. squat)
[1114, 16, 19, 20]. It appears as though low variation in
exercise selection or targeted muscle groups may increase
the likelihood of training maladaptation due to a high
increase in concentrated training load with limited time to
recover. Therefore, coaches and athletes should use caution
when programming an overload period targeting a specific
lift or muscle group. Collectively, high training frequency,
high training intensity and training monotony appear to
increase the likelihood of training maladaptation. However,
confounding factors such as training status must be consid-
ered in future studies.
4.1.3 Biochemistry
Various biochemical markers have also been investigated to
gain a greater understanding of the potential mechanisms of
overtraining in resistance exercise. Nine studies measured
biochemical responses following an overload training period
that resulted in a decrease in performance [1113, 1518,
20, 21]. Marked responses were observed in overload par-
ticipants in comparison to control participants in hormone
levels (cortisol, T:C ratio, free T:C ratio and catecholamines)
[11, 12, 20], blood biomarkers and muscle damage markers
(lactate and creatine kinase, respectively) [13]. However,
the biochemical responses of overtraining remain unknown
due to the variability of results and lack of studies that have
measured the time course changes in performance required
to accurately diagnose maladaptive training conditions. A
recent systematic review of the hormonal aspects of over-
training by Cadegiani etal. [36] also recognised that the
improper diagnosis of FOR, NFOR and OTS is a significant
problem in overtraining literature. Furthermore, biochemical
markers have been unable to distinguish between a normal
training response, acute fatigue, FOR, NFOR and OTS. Fur-
ther research is needed to understand the biochemical altera-
tions during training maladaptation and to determine the
validity and reliability of biomarkers for monitoring over-
training. It has previously been suggested that overtraining
can result in differential biochemical responses depending
on whether high relative intensity or high-volume resist-
ance training is performed [8, 37]. However, due to the lack
of studies that have appropriately established overtraining
through high-volume and/or high-intensity training proto-
cols, comparisons cannot be made; therefore, this theory
cannot be corroborated.
C.Grandou et al.
4.1.4 Physiology
Physiological measures have previously been investigated
as tools to monitor and/or diagnose overtraining. However,
relatively few studies have investigated the response of
physiological measures to overtraining in resistance exer-
cise. Fry etal. [13] measured resting heart rate upon waking
and reported no changes throughout 2weeks of overload
resistance training. However, the multifactorial causes of
variation in basal heart rate may limit its ability to moni-
tor for overtraining in resistance exercise. Additionally,
Margonis etal. [18] reported on knee range of motion as
a measure of the swelling/oedema response to overtraining
in resistance exercise. The authors reported a decrease in
range of motion indicative of swelling and muscle micro
trauma following the overload training intervention. How-
ever, inflammatory measures may be unable to distinguish
between acute fatigue, FOR, NFOR and OTS. The muscle
physiology mechanisms that underpin the decline in perfor-
mance characteristic of overtraining in resistance exercise
have been investigated by relatively few studies [16, 19, 20].
Skeletal muscle fibre composition and muscle fibre contrac-
tile properties have previously been examined. Declines in
β2-AR density and altered MAPK activity may be responsi-
ble for the muscle maladaptation associated with overtrain-
ing. However, future research is needed to determine the
validity and reliability of physiological measures as tools
to monitor overtraining in resistance exercise. Furthermore,
physiological monitoring markers must reflect the nature and
mechanisms of resistance training.
4.1.5 Psychology andPerceptual Responses
It is well established that the presence of negative psycho-
logical and perceptual responses coincides with overtraining
in endurance populations [7]. However, relatively few stud-
ies have used psychological and perceptual monitoring tools
in resistance exercise overtraining interventions. Increases in
delayed onset muscle soreness and pain as well as decreases
in perceived recovery status and perception of strength have
been reported among interventions that demonstrated a
decrease in performance [13, 18]. These are expected find-
ings given that the process of overtraining involves an imbal-
ance of training stress and recovery. In contrast to the endur-
ance literature, Fry etal. [13] reported slight decreases in
anxiety following an overload training period which resulted
in decreases in 1RM strength. The authors suggested that
overtraining through high-intensity resistance exercise may
produce different psychological responses in comparison
to high-volume endurance training. At present, percep-
tual measures of soreness and recovery status may provide
information concerning increases in training load. However,
these tools are yet to be established as reliable indicators of
overtraining in resistance exercise. Due to the lack of studies
demonstrating overtraining and investigating psychological
and perceptual responses to overtraining in resistance exer-
cise, no clear consensus can be reached. Future investigators
should combine tools to measure psychological disturbances
with measures of performance to gain a better understanding
of this relationship.
4.2 Limitations
This is the first systematic review to critically appraise the
methodology and results of studies that have attempted to
induce FOR, NFOR or OTS through resistance exercise.
This analysis was limited by the inability to perform a meta-
analysis due to the heterogeneity of study methodologies and
outcomes. Additionally, a possible risk of bias may exist
in the selection of search terms and exclusion criteria as
defined by the authors. However, this review followed pro-
tocols as recommended by the AMSTAR 2 and PRISMA
guidelines. Furthermore, due to the criteria required to
diagnose overtraining, an adapted risk of bias assessment
tool was required to accurately reflect the quality of studies.
Limitations are present in this assessment as a clear judge-
ment about the risk of bias arising from each domain was not
reflected with a validated assessment tool (i.e. Cochrane risk
of bias appraisal tool). To address this limitation, an adapted
risk of bias assessment tool was used. Additionally, a variety
of limitations exist in the included studies. Many studies
did not demonstrate decreases in performance or measure
the time course changes in performance during a follow-up
period. Due to these methodological limitations, an accurate
diagnosis of FOR, NFOR or OTS was impossible. The lack
of standardised diagnostic criteria and the inconsistency and
variability in measurements of performance, biochemistry,
physiology and psychology amongst studies make it difficult
to establish the relationship between overtraining and resist-
ance exercise.
4.3 Future Research
Given the negative impact of overtraining on athletic perfor-
mance, it is essential that research in this area is examined
critically. Due to the lack of studies demonstrating decreases
in performance and implementing follow-up measures,
further research is required to develop an understanding
of overtraining in resistance exercise. The prevalence and
symptoms of overtraining in resistance exercise should be
further investigated given the lack of longitudinal studies in
resistance-trained populations. Future studies must imple-
ment resistance training interventions that are reflective of
the sport/discipline to maintain ecological validity; however,
the authors should report the primary performance measure.
To gain a better understanding of the effects of overtraining,
Overtraining in Resistance Exercise…
future studies should attempt to increase consistency
amongst measured parameters (biochemical, physiological
and psychological markers). There is also a need to inves-
tigate the time course changes in performance, biochem-
istry, physiology and psychology throughout the recovery/
follow-up stage. Future investigators should also consider
examining the aetiology of high-volume versus high rela-
tive intensity resistance exercise overtraining. Additionally,
future authors should control for confounding factors (i.e.
nutritional and sleep characteristics) as these factors may
play a role in the development of the OTS [38]. As was
recently done in an overtraining study by Cadegiani etal.
[38], future authors should consider utilising the flowchart
proposed by Meeusen etal. [7] to diagnose OTS and account
for confounding factors.
It is necessary to consider the clinical and economic
implications of studying overtraining in athletic populations.
Future researchers must consider the impact of subjecting
participants to increased training loads over long periods in
an attempt to induce overtraining. This may result in long-
term decrements in performance and increased susceptibility
to physical or psychological illness and injury. Additionally,
overtraining may be experienced differently amongst partici-
pants. Future studies must consider interindividual variabil-
ity in response to increases in training load. While the dif-
ficulties and ethical considerations of inducing overtraining
in athletic populations are appreciated, well-designed studies
with demonstrated decreases in performance and follow-up
measures are required to develop a greater understanding of
overtraining in resistance exercise.
5 Conclusion
The primary aim of this review was to critically analyse the
existing literature to elucidate the mechanisms that underlie
overtraining in resistance exercise. Despite the potentially
serious implications of overtraining in athletic populations,
to date, there is insufficient literature investigating the effects
of FOR, NFOR and OTS in resistance exercise. The majority
of previous resistance-based overtraining interventions fail
to demonstrate decrements in training-specific performance.
Furthermore, many studies do not accurately measure the
length of recovery and time course changes in physical per-
formance. It is apparent that the misdiagnosis of overtraining
is a significant problem in previous research. However, it is
necessary to mention that whilst many studies did not appro-
priately establish FOR, NFOR or OTS they still provide
valuable information regarding the physiological alterations
and potential mechanisms of resistance training fatigue.
At present, there is insufficient evidence to draw accu-
rate conclusions on the effects of overtraining in resist-
ance exercise. No diagnostic tool other than a decrease in
sport-specific performance can be taken as an indicator of
overtraining in resistance exercise. Given the current evi-
dence the exact role of biochemical, physiological and psy-
chological markers in overtraining in resistance exercise
remains equivocal. Athletes and coaches should regularly
monitor a combination of performance, biochemical, physi-
ological and psychological variables to identify athletes that
may be approaching training maladaptation. The causes and
pathogenic nature of overtraining remain unclear; however,
frequent, high-intensity, monotonous resistance training
appears to increase an athlete’s susceptibility to overtrain-
ing. However, caution must be exercised when interpreting
these findings due to the lack of interventions which have
induced FOR, NFOR or OTS through resistance exercise.
Data availability statement All data generated or analysed during
this study are included in this published article (and its supplementary
information files).
Compliance with ethical standards
Funding No sources of funding were used to assist in the preparation
of this article.
Conflict of interest Clementine Grandou, Lee Wallace, Franco M.
Impellizzeri, Nicholas G. Allen and Aaron J. Coutts declare that they
have no conflicts of interest relevant to the content of this review.
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... OT is the process of undertaking training with an increase in training volume or intensity of effort, whilst OTS would be a possible outcome of OT. Our recent scoping review [5], as well as the explorative systematic review published by Grandou et al. [6], reported minimal evidence of OTS in either competitive strength sports or those undertaking periods of resistance exercise, even after purposeful attempts to impair performance. Our research has also reported that high-performance strength coaches are not concerned with the risk of OTS, and rarely consider such the disorder a consequence of resistance exercise [4]. ...
... Whilst research into resistance exercise OT has gathered attention from sports scientists in recent years, the field has traditionally focused on the endurance athlete [1,2,12]. Consequently, scientific literature regarding the detection of NFOR and OTS caused by prolonged or excessive resistance exercise is underrepresented [5,6]. ...
... Interestingly, whilst some (at times extremely challenging) protocols have been developed to induce OT, the incidence of NFOR/OTS is still low. Studies that have failed to report a state of NFOR/OTS are more likely to reflect normal strength training practices [6]. ...
Full-text available
Short-term periods of increased resistance exercise training are often used by athletes to enhance performance, and can induce functional overreaching (FOR), resulting in improved physical capabilities. Non-functional overreaching (NFOR) or overtraining syndrome (OTS), occur when training demand is applied for prolonged periods without sufficient recovery. Overtraining (OT) describes the imbalance between training demand and recovery, resulting in diminished performance. While research into the effects of resistance exercise OT has gathered attention from sports scientists in recent years, the current research landscape is heterogeneous, disparate, and underrepresented in the literature. To date, no studies have determined a reliable physiological or psychological marker to assist in the early detection of NFOR or OTS following periods of resistance exercise OT. The purpose of this work is to highlight the conceptual and methodological limitations within some of the current literature, and to propose directions for future research to enhance current understanding.
... The OTS is characterized by a long-term reduction in performance lasting several weeks to months (Meeusen et al., 2013). To date, no single test or assessment has been developed that can reliably detect the transitory point where periods of increased training demand such as POR result in either FOR or NFOR/OTS, making it difficult for coaches to identify optimal training demand to achieve FOR and avoid maladaptive states such as NFOR/OTS (Fry and Kraemer, 1997;Bell et al., 2020;Grandou et al., 2020b). The latest consensus, in the scientific community, suggests that OTS and NFOR can only be differentiated by retrospective recovery time-course, and not the type of training stress, the magnitude of impairment, or profile of symptoms (Meeusen et al., 2013). ...
... However, performance plateau or NFOR has been reported in others (Fry et al., 1994c(Fry et al., ,d, 1998(Fry et al., , 2006Purdom et al., 2021). Overall, the number of studies reporting performance improvement after a period of high training demand (i.e., FOR) outweigh those that have observed NFOR (Bell et al., 2020;Grandou et al., 2020b). There is only minimal evidence that true OTS has occurred in either competitive strength athletes or in athletes undertaking resistance-based exercise (Bell et al., 2020;Grandou et al., 2020a,b). ...
... Such protocols have incorporated either single exercise (typically the barbell back squat) (Fry et al., 1994a(Fry et al., ,c,d, 1998(Fry et al., , 2000b(Fry et al., , 2006Nicoll et al., 2016;Sterczala et al., 2017) and multiple exercises (Ratamess et al., 2003;Volek et al., 2004;Fatouros et al., 2006;Kraemer et al., 2006;Sharp and Pearson, 2010;Lowery et al., 2016;Drake et al., 2017), and both traditional strength-based exercises (squat variations, pulls and presses) and sport-specific exercises (snatch, clean and jerk, throwing drills) (Fry et al., 1993(Fry et al., , 2000aHartman et al., 2007;Bazyler et al., 2017) have been selected. Overall, the number of studies reporting either no performance maladaptation (i.e., return to baseline) or performance improvement outweigh those that have observed NFOR/OTS (Bell et al., 2020;Grandou et al., 2020b). Taken as a body of literature, these protocols indicate which types of training might increase susceptibility to NFOR/OTS, but due to methodological heterogeneity makes comparisons between research studies difficult. ...
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Functional overreaching (FOR) occurs when athletes experience improved athletic capabilities in the days and weeks following short-term periods of increased training demand. However, prolonged high training demand with insufficient recovery may also lead to non-functional overreaching (NFOR) or the overtraining syndrome (OTS). The aim of this research was to explore strength coaches' perceptions and experiences of planned overreaching (POR); short-term periods of increased training demand designed to improve athletic performance. Fourteen high-performance strength coaches (weightlifting; n = 5, powerlifting; n = 4, sprinting; n = 2, throws; n = 2, jumps; n = 1) participated in semistructured interviews. Reflexive thematic analysis identified 3 themes: creating enough challenge, training prescription, and questioning the risk to reward. POR was implemented for a 7 to 14 day training cycle and facilitated through increased daily/weekly training volume and/or training intensity. Participants implemented POR in the weeks (~5–8 weeks) preceding competition to allow sufficient time for performance restoration and improvement to occur. Short-term decreased performance capacity, both during and in the days to weeks following training, was an anticipated by-product of POR, and at times used as a benchmark to confirm that training demand was sufficiently challenging. Some participants chose not to implement POR due to a lack of knowledge, confidence, and/or perceived increased risk of athlete training maladaptation. Additionally, this research highlights the potential dichotomy between POR protocols used by strength coaches to enhance athletic performance and those used for the purpose of inducing training maladaptation for diagnostic identification.
... In the specific recovery, the competitive group showed lower averages when compared to the non-competitive group, especially during the competitive period, no significant difference was observed in the intragroup analysis. It may thus be related to the rhythm of training and competitions, associated with insufficient recovery, exceeding the athlete's tolerance (Grandou et al., 2020;Oliver-López et al., 2022). ...
... In our findings we could observe something similar with the assumptions of the literature, there is a direct relationship between the period of competition and the behavioral level of the sample of competitors when compared to non-competitors (Grandou et al., 2020;Zanini et al., 2018). However, it appears that there is a scarcity of studies that directly report the emotional aspect in CrossFit practitioners during a period of competition, therefore, it is necessary to monitor and follow the training load within the modality. ...
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Original Article Comparison between mood states, stress and recovery in CrossFit® competitors and non-competitors. Abstract: Currently, there is an increase in the demand for sports and physical exercises, which are the most effective way to promote health, self-esteem and prevent bad habits. In this context, the practice of CrossFit® attracts new practitioners every day, given the expectation of the challenge linked to the practice due to high intensity training, in this sense still, many feel attracted to competitions in the modality. However, high training loads associated with demands can bring changes in the level of stress associated with abrupt changes in mood. Thus, the present study aims to identify and analyze levels of stress and recovery, and the mood of CrossFit® competitors and non-competitors. The BRUMS instrument was used to measure the mood level and the RESTQ 76 to determine the levels of stress and recovery. The results demonstrate that there was a difference between the pre-competitive and competitive periods for the group of competitors for the variables tension (48.27 ± 36.36%, p = 0.05) and post-competition (79.31 ± 20.45%, p = 0.002), intergroup difference during the competitive period for depression [1380 ± 180.64%, X²(2) = 3.961, p = 0.05]; changes in anger were observed during pre-competitive and competitive periods (247.93 ± 33.14%, p = 0.041) for the competitive group, and during the recovery period (43.38 ± 27.64%, p = 0.048), in addition, difference between the analysis groups [109.45 ± 34.83%, X² (2) = 3.116, p = 0.043], vigor showed a significant reduction for the competitor group, and, intergroup difference during the study [X² (2) = 4,685; p = 0.03], in addition, there was a difference between groups for confusion (406.97 ± 25.98%, f = 4.707, p= 0.041); in the stress analysis, the specific stress showed a difference for the competitor group (31.15 ± 15.78%, p = 0.021), in addition to demonstrating a difference in the analysis between groups (39.94 ± 25.54%, f = 7.321, p = 0.019), the global stress in turn, it showed a difference between the groups (43.77 ± 36%, f = 5.068, p = 0.44). The data therefore demonstrate that CrossFit practitioners submitted to periods of competition have changes in their mood profile and stress levels when compared to non-competitive individuals submitted to the same training routines.
... Otras críticas metodológicas que se han reportado en la literatura incluyen la utilización inconsistente de variables manipuladas en los estudios, como la cantidad de repeticiones, la intensidad de estas, la duración de las sesiones de ejercicio, o el descanso entre las sesiones de entrenamiento [509] . Otros aspectos críticos para obtener un resultado consistente y replicable son el tipo de prueba física que se utilice (e.g., máxima, submáxima), el instrumento y el protocolo de medición (e.g., nuevo o estandarizado, con propiedades psicométricas de validez y confiabilidad), hora del día en la que se realizan las pruebas para evitar un posible efecto circadiano en la variable de interés, la alimentación previa, durante o posterior a la medición de alguna cualidad física o cognitiva, el tamaño de la muestra y la potencia estadística, la modalidad de entrenamiento, la familiarización con la prueba de rendimiento y su comodidad, el cegamiento al tratamiento o intervención, y el grado de involucramiento muscular de esta (e.g., cuerpo total, tren inferior o tren superior) [293][373] [509] . ...
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Este libro es la culminación de un proyecto para el mejoramiento de la labor docente y estudiantil inscrito en la Vicerrectoría de Docencia de la Universidad de Costa Rica con el código PD-EF-1503-2021. Los autores exponen argumentos basados en evidencia científica con el propósito de estimular investigación de alta calidad en las Ciencias del Movimiento Humano. A la vez, agradecen el apoyo de la Escuela de Educación Física y Deportes y del Centro de Investigación en Ciencias del Movimiento Humano de la Universidad de Costa Rica, así como a colegas investigadores con quienes han podido compartir y publicar sus investigaciones. Esta es una obra que requiere conocimientos básicos en diseños de investigación y análisis estadístico; por lo que se presenta como un material de consulta de nivel intermedio a avanzado, que será especialmente útil en programas de maestría y doctorado. La obra se presenta en dos capítulos; uno acerca de avances metodológicos, y otro, que presenta avances estadísticos. El primer capítulo introduce conceptos actualizados referentes a metodologías de investigación utilizadas en estudios publicados en revistas científicas de alta calidad, de manera que los lectores puedan apreciar metodologías de vanguardia que se utilizan para responder preguntas de investigación relevantes para las Ciencias del Movimiento Humano. El segundo capítulo introduce técnicas novedosas de análisis de datos que se han incorporado al universo de los investigadores para poder afrontar la cada vez más compleja cantidad de información recopilada en los estudios. Además, la integración de ambos capítulos ofrece nuevas oportunidades para el trabajo inter, multi y transdisciplinario, aceptando con humildad que un proceso de investigación se ve claramente favorecido por las diferentes perspectivas de profesionales unidos para resolver los principales problemas que afronta la sociedad en la búsqueda del conocimiento.
... Bodybuilders have been observed to experience a loss of muscle strength in the scapular stabilizers and rotator cuff muscles. Such strength imbalances may lead to a poor scapulohumeral rhythm during shoulder elevation (Kolber et al., 2009;Grandou et al., 2020). ...
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Background. Resistance-trained males aim to increase their overall health, strength and fitness level. Many resistance-trained males aiming to increase their strength neglect the muscles that stabilize the scapular and glenohumeral joints. The shoulder joint is among the most frequently injured areas in resistance-trained males. In addition, strength training displays different effects in young and old individuals. The study purpose was to investigate the effects of stability and mobility exercises on range of motion, posture and body awareness in resistance-trained males with shoulder immobility. Materials and methods. Thirty-two resistance-trained males diagnosed with shoulder immobility were divided into two groups according to their age ranges (G1: Adult, G2: Young Adult). The program consisting of mobility and stability exercises was applied 3 days a week for 8 weeks. The participants were evaluated with a universal goniometer, the New York Posture Rating, and the Body Awareness Questionnaire before and after the treatment lasting 8 weeks. Results. Following the 8-week treatment, improvements in body awareness and range of motion were observed in all participants (p≤0.05). There were improvements in the scores of the New York Posture Rating and Body Awareness Questionnaire in both groups, but they were not statistically significant (p≥0.05). Conclusions. An exercise program combining stability and mobility exercises was applied to resistance-trained males with shoulder immobility and it was observed to have positive effects on the range of motion of the joint, body awareness and posture. We are of the opinion that various types of exercise should be implemented when planning exercise programs.
... Although in the present BioMed Research International study the T : C ratio showed greater levels in the XX group (Figure 2(c)), it is possible to interpret that the RR/RX group showed a greater catabolic tendency after the stimulus due to the higher levels of cortisol on this group. However, the analysis of the T : C ratio is only a tool, and it should not be analyzed in isolation to determine the overtraining status [45]. It was observed that despite the lower training volume of individuals with genotype XX, this group presented a greater inflammatory response and more referred pain in relation to the RR/RX genotypes. ...
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The objective of this study was to verify the influence of the ACTN3 R577X polymorphism on muscle damage and the inflammatory response after an acute strength training (ST) session. Twenty-seven healthy male individuals (age: 25 ± 4.3 years) participated in the study, including 18 RR/RX and 9 XX individuals. The participants were divided into two groups (RR/RX and XX groups) and subjected to an acute ST session, which consisted of a series of leg press, leg extension machine, and seated leg curl machine. The volunteers were instructed to perform the greatest volume of work until concentric muscle failure. Each volunteer’s performance was analyzed as the load and total volume of training, and the blood concentrations of C-C motif chemokine ligand 2 (CCL2), interleukin-8 (IL-8), creatine kinase (CK), lactate dehydrogenase (LDH), myoglobin, testosterone, and cortisol were measured before the ST session and 30 min and 24 h postsession. The ACTN3 R577X polymorphism effect was observed, with increased concentrations of CCL2 ( p < 0.01 ), IL-8 ( p < 0.01 ), and LDH ( p < 0.001 ) in XX individuals. There was an increase in the concentration of CK in the RR/RX group compared to XX at 24 h after training ( p > 0.01 ). The testosterone/cortisol ratio increased more markedly in the XX group ( p < 0.001 ). Regarding performance, the RR/RX group presented higher load and total volume values in the training exercises when compared to the XX group ( p < 0.05 ). However, the XX group presented higher values of delayed onset muscle soreness (DOMS) than the RR/RX group ( p < 0.05 ). The influence of ACTN3 R577X polymorphism on muscle damage and the inflammatory response was observed after an acute ST session, indicating that the RR/RX genotype shows more muscle damage and a catabolic profile due to a better performance in this activity, while the XX genotype shows more DOMS.
... Where excessive fatigue goes unmonitored over protracted periods of time, this may lead exposure to injury risk including overreaching or overtraining which will impact on performance (18). When fatigue levels are not accurately monitored and tracked, this could lead to a decrement in overall performance and injury risk (19). When examining the values derived from the objective RSImod (CMJ-countermovement vertical jump) to determine the effect of workload and fatigue on neuromuscular performance. ...
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Managing the health and wellbeing of full-time professional athletes is a multifaceted task. In elite high-performance environments, medical staff and strength training coaches attempt to identify improved methods to monitor player health. Monitoring player health could indicate potential injury risk and assist in adjustments to training and workload management. Measuring fatigue is a notable component of monitoring player readiness before and after training sessions, and after competitive fixtures. In the present study, a novel method of gathering non-invasive player data was investigated by utilizing the Omegawave (OW) to monitor direct current (DC) potential brainwave activity. This method allowed for non-invasive data gathering to assess recovery, player readiness and indicators of workload that may affect optimal performance. DC potential is based on recording low electrical frequencies (>0.5 Hz) that is derived from (1) Stabilization point of DC potential (mV), (2) Stabilization time (1.0–7.0) and (3) Curve shape (1.0–7.0). These measures evaluate the athlete's internal stress, readiness to perform, and neurological function through DC potential brain wave activity and heart rate variability (HRV) assessments. The primary aim of this case series was to compare the efficacy of objective DC potential brainwave activity measurements (neurological function) with neuromuscular fatigue data using reactive strength index modified (RSImod) and profile of mood states (POMS) questionnaires to assess a player's state of readiness to train. The participants in this study were eleven male senior professional rugby union players with a mean stature (±SD) of 185.2 ± 8.6 cm, mass of 101.1 ± 12.9 kg, and age of 27.1 ± 2.1 years. All players were tested 3 days per week over a 6-week mid-season period. Results from this case study suggest that DC potentials could be used as an objective measure to indicate player readiness and managing individual player workload. The final analyses identified a weak negative correlation (r = −0.17) between the RSImod data and the DC potential data was observed. DC potential brainwave activity data could be used in conjunction with subjective measures such as POMS, RSImod and reported injury status to adjust player daily activity.
... Intriguingly, although similar training volume and duration, sRPE and strain were similar between groups, but rest-pause training promoted the highest training monotony, and it can be partially explained by training variables, such as concentric failure (Hiscock et al., 2015). It is widely known that long-term low variation in imposed training loads can lead to lack of adaptation; moreover, training monotony has been associated to increased susceptibility to nonfunctional overreaching and/or overtraining, leading to elevated risk of injury and illness (Conlon et al., 2018;Grandou et al., 2020). ...
Purpose: We investigated the effect of drop-set (DS) and rest-pause (RP) systems compared to traditional (TRAD) resistance training on muscular adaptations and psychophysiological responses. Methods: Twenty-seven trained men (age: 23.4 ± 3.4 years; resistance training experience: 5.1 ± 1.7 years) were assigned to experimental groups (DS: n = 9, 3 × 10 repetitions at 75% with 6 additional repetitions at 55% 1RM; RP: n = 9, 3 × 16 repetitions at 75% 1RM; TRAD: n = 9, 4 × 12 repetitions at 70% 1RM) and performed lower-limb training sessions twice a week for 8 weeks. Maximum dynamic strength (1RM) and localized muscular endurance (LME) tests were performed in 45° leg press at baseline and post intervention. Session-RPE was assessed 15 min after the end of each training session. Results: A significant time vs. group interaction was observed for 1RM (p = .012) and LME (p < .0001). Post hoc comparisons revealed that RP elicited greater gains in muscular strength than DS (p = .044) but not TRAD (p = .116); and DS elicited greater LME than RP (p < .001) and TRAD (p = .001). No statistical differences were observed in Session-RPE and training strain between conditions; however, RP promoted higher training monotony (p = .036) than DS and TRAD. Conclusions: The DS and RP systems have a potential role in training programs aiming to promote muscle strength and localized muscular endurance adaptations, respectively. However, RP may promote higher training monotony than DS and TRAD, even though the other psychophysiological responses are similar.
... Sex differences were not analyzed in this study as it was underpowered. In resistance training, the occurrence of either syndrome is not as well understood, and it has recently been reported that there is little evidence of true OTS occurrence in strength sports (Bell et al., 2020;Grandou et al., 2020). However, non-functional overreaching in resistance training has been observed in chronic high-volume or high-intensity conditions (Bell et al., 2020). ...
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As the fields of kinesiology, exercise science, and human movement developed, the majority of the research focused on male physiology and extrapolated findings to females. In the medical sphere, basing practice on data developed in only males resulted in the removal of drugs from the market in the late 1990s due to severe side effects (some life-threatening) in females that were not observed in males. In response to substantial evidence demonstrating exercise-induced health benefits, exercise is often promoted as a key modality in disease prevention, management, and rehabilitation. However, much like the early days of drug development, a historical literature knowledge base of predominantly male studies may leave the exercise field vulnerable to overlooking potentially key biological differences in males and females that may be important to consider in prescribing exercise (e.g., how exercise responses may differ between sexes and whether there are optimal approaches to consider for females that differ from conventional approaches that are based on male physiology). Thus, this review will discuss anatomical, physiological, and skeletal muscle molecular differences that may contribute to sex differences in exercise responses, as well as clinical considerations based on this knowledge in athletic and general populations over the continuum of age. Finally, this review summarizes the current gaps in knowledge, highlights the areas ripe for future research, and considerations for sex-cognizant research in exercise fields.
Despite the controversy surrounding periodization, it has been assumed over the years as the key tool in training planning for the development and achievement of high-level performance, in individual sports. Given the enormous density of nowadays competitive calendar and the athletes’ responsibilities towards their sponsors, the challenge is to train with quality, managing fatigue through specific training programs that correctly handle the load applied to the athlete. The scientific boom experienced today and the availability of information from areas such as physiology, biomechanics, biochemistry and sports training, allowed to overcome myths, improve training prescription/control and the development of new approaches to training periodization in elite athletes. The model presented here has as main characteristics to be timeless and dimensionless. That is, each “momentum” depends exclusively on the athlete’s body feedback in relation to the training loads, indicated by the biomarkers used. The duration of “momentums” and “macrocycles” depends on the athlete’s performance, ballast and physiological wear (internal biomonitored load). The purpose of this chapter is to present an overview of the components to be considered in individual sports training, their control and how the theory is translated into practice.
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Background Overtraining syndrome (OTS), functional (FOR) and non-functional overreaching (NFOR) are conditions diagnosed in athletes with decreased performance and fatigue, triggered by metabolic, immune, hormonal and other dysfunctions and resulted from an imbalance between training stress and proper recovery. Despite previous descriptions, there is a lack of a review that discloses all hormonal findings in OTS/FOR/NFOR. The aim of this systematic review is to evaluate whether and which roles hormones play in OTS/FOR/NFOR. Methods A systematic search up to June 15th, 2017 was performed in the PUBMED, MEDLINE and Cochrane databases following PRISMA protocol, with the expressions: (1)overtraining, (2)overreaching, (3)overtrained, (4)overreached, or (5)underperformance, and (plus) (a)hormone, (b)hormonal, (c)endocrine, (d)adrenal, (e)cortisol, (f)GH, (g)ACTH, (h)testosterone, (i)IGF-1, (j)TSH, (k)T4, (l)T3, (m)LH, (n)FSH, (o)prolactin, (p) IGFBP-3 and related articles. Results A total of 38 studies were selected. Basal levels of hormones were mostly normal in athletes with OTS/FOR/NFOR compared with healthy athletes. Distinctly, stimulation tests, mainly performed in maximal exercise conditions, showed blunted GH and ACTH responses in OTS/FOR/NFOR athletes, whereas cortisol and plasma catecholamines showed conflicting findings and the other hormones responded normally. Conclusion Basal hormone levels are not good predictor but blunted ACTH and GH responses to stimulation tests may be good predictors of OTS/FOR/NFOR.
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The effects of a recovery drink on overreaching induced by high frequency, high power resistance exercise was assessed. Resistance trained men were assigned to a supplemented (SUP, n = 8), placebo (PL, n = 3) or control (CON, n = 6) groups. All groups completed two weeks of familiarization training using the barbell squat. In week three, SUP and PL performed ten sets of five repetitions of speed squats twice daily, for a total of 15 training sessions. CON maintained their prior training schedule. Data were collected before week three (T1), after week three (T2) and after a week of recovery by training cessation (T3). During week three, SUP consumed an amino acid, carbohydrate and creatine monohydrate containing recovery drink immediately after each training bout. PL was provided a drink of similar appearance and taste but containing minimal nutritional value. At T2, both SUP and PL decreased mean squat velocity and power at 70% 1RM. Additionally, SUP and PL decreased muscle β2-adrenergic receptor (β2-AR) expression by 61 and 83%, respectively. Increases in the ratio of nocturnal urinary epinephrine/β2-AR ratio (EPI: β2AR) for SUP and PL suggested impaired sympathetic nervous system sensitivity. SUP demonstrated a smaller decrease in β2-AR expression and a lower EPI: β2AR, suggesting the recovery drink attenuated the detrimental effects of overreaching on the sympathetic activity. In conclusion, high power resistance exercise overreaching can induce performance decrements and impair sympathetic activity, but these effects may be attenuated by supplementation.
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This letter addresses a number of discrepancies found in several publications related HMB-FA and ATP supplementation.
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PurposeMany physiological maladaptations persist after overreaching and overtraining resistance exercise (RE). However, no studies have investigated changes in mitogen-activated protein kinases (MAPK) after overtraining in humans, despite their critical role regulating exercise-induced muscular adaptations. The purpose of this study was to describe the changes in total and resting phosphorylation status of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun NH2-terminal kinase (JNK) and p38-MAPK following a period of RE overreaching or overtraining. Methods Following 2–4 weeks of normal training (low volume/low intensity), two groups of males performed either a high-power overreaching protocol (HPOR n = 6, mean ± SD, age 23 ± 3.4 years, mass 86.5 ± 17.7 kg, height 1.77 ± 0.06 m) or high-intensity overtraining protocol (HIOT n = 8, age 19.8 ± 1.8 years, mass 76.8 ± 6.7 kg, height 1.8 ± 0.06 m). Resting muscle biopsies were obtained at baseline (BL; end of normal training period) and 24 h after the final session of stressful training (i.e., HPOR or HIOT programs). Total MAPK and ratio of phosphorylated/total (p-MAPK)- ERK1/2, JNK, and p38-MAPK were analyzed via western blotting. 2 × 2 (group × time) ANOVA determined differences in MAPK between BL and post-training protocols. ResultsCompared to BL, total-ERK increased after HPOR, but decreased after HIOT (p ≤ 0.05). p-ERK1/2/total-ERK increased after HIOT (p ≤ 0.05). The ratio of p-JNK/total-JNK and p-ERK1/2/total-ERK decreased after HPOR (p ≤ 0.05); however, this result was primarily due to increased total MAPK content. p-p38-MAPK decreased after HPOR (p ≤ 0.05). Conclusion Total and p-MAPK are differentially expressed after HPOR and HIOT RE. These changes are likely involved in the maladaptation reported in overreaching and overtraining exercise. This is the first study describing altered MAPK in RE overtrained and overreached humans.
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Assessing current fatigue of athletes to fine-tune training prescriptions is a critical task in competitive sports. Blood-borne surrogate markers are widely used despite the scarcity of validation trials with representative subjects and interventions. Moreover, differences between training modes and disciplines (e.g. due to differences in eccentric force production or calorie turnover) have rarely been studied within a consistent design. Therefore, we investigated blood-borne fatigue markers during and after discipline-specific simulated training camps. A comprehensive panel of blood-born indicators was measured in 73 competitive athletes (28 cyclists, 22 team sports, 23 strength) at 3 time-points: after a run-in resting phase (d 1), after a 6-day induction of fatigue (d 8) and following a subsequent 2-day recovery period (d 11). Venous blood samples were collected between 8 and 10 a.m. Courses of blood-borne indicators are considered as fatigue dependent if a significant deviation from baseline is present at day 8 (Δfatigue) which significantly regresses towards baseline until day 11 (Δrecovery). With cycling, a fatigue dependent course was observed for creatine kinase (CK; Δfatigue 54±84 U/l; Δrecovery -60±83 U/l), urea (Δfatigue 11±9 mg/dl; Δrecovery -10±10 mg/dl), free testosterone (Δfatigue -1.3±2.1 pg/ml; Δrecovery 0.8±1.5 pg/ml) and insulin linke growth factor 1 (IGF-1; Δfatigue -56±28 ng/ml; Δrecovery 53±29 ng/ml). For urea and IGF-1 95% confidence intervals for days 1 and 11 did not overlap with day 8. With strength and high-intensity interval training, respectively, fatigue-dependent courses and separated 95% confidence intervals were present for CK (strength: Δfatigue 582±649 U/l; Δrecovery -618±419 U/l; HIIT: Δfatigue 863±952 U/l; Δrecovery -741±842 U/l) only. These results indicate that, within a comprehensive panel of blood-borne markers, changes in fatigue are most accurately reflected by urea and IGF-1 for cycling and by CK for strength training and team sport players.
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Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field [1],[2], and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research [3], and some health care journals are moving in this direction [4]. As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews. Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in four leading medical journals in 1985 and 1986 and found that none met all eight explicit scientific criteria, such as a quality assessment of included studies [5]. In 1987, Sacks and colleagues [6] evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in six domains. Reporting was generally poor; between one and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement [7]. In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials [8]. In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1). Box 1: Conceptual Issues in the Evolution from QUOROM to PRISMA Completing a Systematic Review Is an Iterative Process The conduct of a systematic review depends heavily on the scope and quality of included studies: thus systematic reviewers may need to modify their original review protocol during its conduct. Any systematic review reporting guideline should recommend that such changes can be reported and explained without suggesting that they are inappropriate. The PRISMA Statement (Items 5, 11, 16, and 23) acknowledges this iterative process. Aside from Cochrane reviews, all of which should have a protocol, only about 10% of systematic reviewers report working from a protocol [22]. Without a protocol that is publicly accessible, it is difficult to judge between appropriate and inappropriate modifications.
A balanced order, double-blind, cross-over design study, measured the effects of 800 mg soybean-derived phosphatidylserine (PS) or placebo (C), administered daily during 2-week intense weight training, on cortisol (CT), ACTH, testosterone (TS), luteinising hormone (LH), creatine kinase (CK) activity, subjective well-being (WB) and muscle soreness (MS) in 11 trained males. Subjects did 5 sets of 10 repetitions for 13 exercises, 4 times a week, for two 2-week periods separated by a 3-week recovery. Resting morning venous blood was sampled 6 times during each 2-week period (T1-T6) and 15 min following the 8th training sessions (T7). WB and MS were estimated using 10-point scales. CT was similar between treatments in T1-T6. CT decreased between T6 and the post-exercise T7 in PS (15.6±1.7 to 10.0±0.9 μg/dl, P<0.05) but not in C. ACTH did not change in PS in T1-T7 but increased in C between T4 (40.6±5.1 pg/ml) and T5 (62.2±10.5 pg/ml), T6 (59.2±7.7 pg/ml), and T7 (63.7+6.1 pg/ml). TS increased in PS between T1 (3.3±0.3 ng/ml) and T3 (4.4±0.5 ng/ml) and fell in both treatments between T3 and T7 (3.3±0.3 ng/ml, PS; 3.3±0.4, C). LH increased significantly between T1 (1.5±0.1 mIU/ml) and T6 (2.2±0.3 mIU/ml) in PS but did not change in C. WB was greater in P than C in T2-T6. In C, WB at T3 was markedly depressed (4.9±0.8). MS increased in both treatments and was greater in C than PS at T2 (2.9±0.4, PS; 4.7±0.7 C) and T5 (2.0±0.5, PS; 3.6±0.9 C). Cortisol decreased in PS after exercise, possibly by depressing ACTH and might have attenuated the negative effects of intense weight training on perception of well-being and muscle soreness.
Overtraining is an imbalance between training and recovery. Short term overtraining or ‘over-reaching’ is reversible within days to weeks. Fatigue accompanied by a number of physical and psychological symptoms in the athlete is an indication of ‘stateness’ or ‘overtraining syndrome’. Staleness is a dysfunction of the neuroendocrine system, localised at hypothalamic level. Staleness may occur when physical and emotional stress exceeds the individual coping capacity. However, the precise mechanism has yet to be established. Clinically the syndrome can be divided into the sympathetic and parasympathetic types, based upon the predominance of sympathetic or parasympathetic activity, respectively. The syndrome and its clinical manifestation can be explained as a stress response. At present, no sensitive and specific tests are available to prevent or diagnose overtraining. The diagnosis is based on the medical history and the clinical presentation. Complete recovery may take weeks to months.