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Monitoring of immunological parameters in adolescentbasketball athletes during and after a sports seasonDiego Trevisan Brunellia, Ariel Rodriguesb, Wendell Arthur Lopesa, Arthur FernandesGásparia, Valéria Bonganhaa, Paulo César Montagnerb, João Paulo Borinb & Cláudia ReginaCavaglieriaa Exercise Physiology Laboratory – FISEX, Faculty of Physical Education, State University ofCampinas (UNICAMP), Campinas, Brazilb Department of Sport Science, Faculty of Physical Education, State University of Campinas(UNICAMP), Campinas, BrazilPublished online: 30 Jan 2014.

To cite this article: Diego Trevisan Brunelli, Ariel Rodrigues, Wendell Arthur Lopes, Arthur Fernandes Gáspari, ValériaBonganha, Paulo César Montagner, João Paulo Borin & Cláudia Regina Cavaglieri , Journal of Sports Sciences (2014):Monitoring of immunological parameters in adolescent basketball athletes during and after a sports season, Journal of SportsSciences, DOI: 10.1080/02640414.2013.878806

To link to this article: http://dx.doi.org/10.1080/02640414.2013.878806

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Monitoring of immunological parameters in adolescent basketballathletes during and after a sports season

DIEGO TREVISAN BRUNELLI1, ARIEL RODRIGUES2, WENDELL ARTHUR LOPES1,ARTHUR FERNANDES GÁSPARI1, VALÉRIA BONGANHA1, PAULO CÉSARMONTAGNER2, JOÃO PAULO BORIN2 & CLÁUDIA REGINA CAVAGLIERI1

1Exercise Physiology Laboratory – FISEX, Faculty of Physical Education, State University of Campinas (UNICAMP),Campinas, Brazil and 2Department of Sport Science, Faculty of Physical Education, State University of Campinas(UNICAMP), Campinas, Brazil

(Accepted 20 December 2013)

AbstractThe objective of the present study was to monitor the immunological and hormonal responses and the occurrence ofupper respiratory symptoms in adolescent basketball athletes during the different stages of a sports season.Anthropometric measures, biochemical analyses (interleukin-6, interleukin-10, tumour necrosis factor-alpha, C-reactiveprotein, testosterone and cortisol), neuromuscular evaluations (standing vertical jumping ability, agility and estimatedVO2max) and leukocyte counts were performed at four moments: 72 h before the season (−72 h); before the season(Pre-season); after six weeks, at the end of the preparatory period (Preparatory); and after 20 weeks, at the end of thecompetitive period (Competitive). Also, the occurrence of upper respiratory symptoms was collected weekly during allstages of the season. There were significant increases in monocytes, cortisol, tumour necrosis factor-alpha and C-reactive protein at the Competitive moment as compared to the Pre-season. In addition, interleukin-10 decreased at theCompetitive moment as compared to the Pre-season. Occurrence of upper respiratory symptoms demonstratedincreases (38%) during the competitive period as compared to the preparatory. These results suggest that periods oftraining and competition could increase the occurrence of upper respiratory symptoms in adolescent athletes and thismay be due to the unwanted effects of an inflammatory process in response to the excessive stress of training andcompetition.

Keywords: adolescents, immune system, training, cytokines, hormones

Introduction

In order to improve physical fitness, athletes often useperiods of heavy physical stress followed by a reduc-tion in stress level to achieve specific adaptations atthe cellular level; thus, in other words the efficiency ofexercise training depends on the training load and onthe athlete’s ability to tolerate it (Eliakim et al., 2009;Jürimäe, Mäestu, Jürimäe, Mangus, & von Duvillard,2011). For this reason, extensive efforts are made toquantify objectively the fine balance between trainingintensity and athlete’s tolerance (Eliakim et al.,2009). Therefore, the monitoring of different vari-ables during a sports season can add to obtain para-meters of increasing, decreasing or maintaining theloads during the training process.

Among these variables, we highlight the immunesystem as an important factor in the preparation of

an athlete during the sports season because periodsof heavy training with transient impaired perfor-mance are associated with innate and acquiredimmune depression (Morgado et al., 2012). In addi-tion, this temporary suppression of the immune sys-tem to environmental threats can lead to occurrenceof episodes of upper respiratory symptoms, whichcan dramatically influence the preparation and com-petitive programmes of an athlete (Kakanis et al.,2010).

Studies performed on adult athletes have foundthat periods of highly demanding training seems tohave a negative impact on function and cell countsof the immune system (Morgado et al., 2012;Rama et al., 2013), as well as increases in cortisolplasma levels and occurrence of upper respiratorysymptoms (Córdova, Sureda, Tur, & Pons, 2010;

Correspondence: Diego Trevisan Brunelli, Exercise Physiology Laboratory – Faculty of Physical Education, State University of Campinas (UNICAMP),Campinas, Brazil. E-mail: dibrunelli@hotmail.com

Journal of Sports Sciences, 2014http://dx.doi.org/10.1080/02640414.2013.878806

© 2014 Taylor & Francis

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Dias et al., 2011; Gleeson, 2007; Rama et al.,2013), and proinflammatory cytokines such astumour necrosis factor-alpha (Rämson, Jürimäe,Jürimäe, & Mäestu, 2008). It has also been arguedthat adolescents and adults may have differentimmunological responses to physical exercise(Timmons, 2007). However, similar research oninteractions between periods of a sports season,the occurrence of upper respiratory symptoms,and the behaviour of the immune system in ado-lescent athletes are very limited. Most studies thathad proposed to evaluate these parameters in thispopulation underwent acute training protocols(Cieslak, Frost, & Klentrou, 2003; Eliakim et al.,2009; Nemet, Rose-Gottron, Mills, & Cooper,2003; Nieman, Kernodle, Henson, Sonnenfeld, &Morton, 2000). Only a few studies featuring indi-vidual sport modalities have looked at the effects ofdifferent periods of training periodisation onimmunological adaptations over an entire season(Henson, Nieman, & Kernodle, 2001; Nemet,Pontello, Rose-Gottron, & Cooper, 2004).Moreover, the immunological responses for differ-ent training periods in adolescent athletes engagedin team sports, which are very popular in these agegroups (Eliakim et al., 2009), have not been stu-died thoroughly.

Furthermore, studies have suggested that theincidence of upper respiratory symptoms, whichare often thought to be a marker of early stages ofovertraining syndrome, were related to excursionsabove individually identifiable thresholds of trainingstrain and monotony (Foster, 1998; Plutur et al.,2004). Therefore, the objective of this study was toevaluate the immune and hormonal responses andthe occurrence of episodes of upper respiratorysymptoms in a group of adolescent athletes duringa basketball season. Thus, we hypothesised: (1) thatthe competitive period would lead to increases oninflammatory and catabolic biomarkers as com-pared to the preparatory period of the season; (2)that there would be a relationship between trainingload indicators and the occurrence of upper respira-tory symptoms.

Methods

Participants

We monitored eleven male adolescent athletes (13.3± 0.6 years, 171.9 ± 4.7 cm, 62.96 ± 9.7 kg, 19.15 ±9.3% fat-free mass), playing in the São Paulo StateRegional Basketball League, Brazil. Exclusion cri-teria included: use of medication that could affectthe immune parameters, diseases or joint/muscleproblems, and less than 80% of frequency and/orinterruption during the training period. All

participants were experienced basketball players(3.1 ± 1.0 playing years) and already had priorexperience with the physical tests performed in thisstudy. All participants were classified as pubertal(3.4 ± 0.5; stage III or IV) as regards secondarysexual characteristics, according to self-assessment(Matsudo & Matsudo, 1994) of the descriptionsproposed by Tanner (1962).

Individuals responsible for each participant wereinformed of the study protocol and purposes andwere asked to sign informed consent before studyparticipation. The experimental methods and proce-dures were approved by the Research EthicsCommittee of the State University of Campinas,Brazil.

Research design

All data in the present study were obtained duringpreparatory and competitive phases of a basketballseason in 2011. The preparatory period comprisedsix weeks of training sessions and the competitiveperiod was composed of 14 weeks of training ses-sions and competitive games. All volunteers wereinstructed to maintain their nutritional habitsthroughout the season in order to avoid immunolo-gical changes deriving from diet.

Anthropometric measures (height, body weightand skinfold thickness), biochemical analyses(interleukin-6, interleukin-10, tumour necrosis fac-tor-alpha, C-reactive protein, testosterone and cor-tisol), neuromuscular evaluations (standing verticaljumping ability, agility and estimated VO2max) andleukocyte counts were performed in four moments:72 h before the beginning of the season (−72 h),after a transitory period during which the athleteshad been released for 12 weeks from their basket-ball training, as a measure of stabilisation of thebiochemical analyses; before the beginning of theseason (Pre-season), which allowed us to establishthe basal values at the beginning of the preparationfor the sport season; after six weeks, at the end ofthe preparatory period (Preparatory); and aftertwenty weeks, at the end of the sport season(Competitive) (Figure 1). The occurrence ofupper respiratory symptoms was recorded weeklyover the entire period of the study. The duration

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Figure 1. Experimental design.

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(in minutes) and the rating of perceived exertionwere recorded 30 min after the end of each session(Foster, 1998) to evaluate the training and compe-titive games load.

Procedures

Training load indicators. All content of the trainingsessions were described by the professionals whoplanned and developed the work with the athletes,without any interference from the researcher, inorder to avoid influences on the sessions or in theplanning and periodisation previously developed andto preserve the characteristics of work by the technicalcommittee. Training sessions comprised three weeklysessions of 98.7 ± 4.5 min duration, each one per-formed for 20 weeks. Training sessions were dividedinto both technical and functional skills according tothe objectives of training (Bompa & Half, 2009).Eight official games were played by the team duringthe competitive period, each one of approximately 90min duration. The duration (in minutes) and therating of perceived exertion were recorded 30 minafter the end of each session to calculate the load ofeach session (Foster, 1998). The following questionwas posed to each participant: “What was the inten-sity of the training in regard to the scale?” The dailytraining load is defined as the relationship betweeneffort quality (intensity) and volume of training.Thus, training load indicators: daily load (the ratingof perceived exertion × daily session training durationin minutes); weekly mean load (the sum of the dailyloads); and total weekly load (the sum of daily loads/number of training days) were determined in arbitraryunits (a.u.) (Foster, 1998). Monotony was calculatedby dividing the daily mean load over each week by thestandard deviation of load, and strain was calculatedby the weekly load × monotony (Foster, 1998).

Anthropometry. Height was measured using a wall-mounted stadiometer, and weight was taken using acalibrated manual scale (Filizola®). Body composi-tion was determined using skinfold thickness with aLange skinfold caliper (Lange, Cambridge ScientificIndustries, Cambridge, MD, USA). The equationof Slaughter et al. (1988) for children and youthswas used to estimate body density using the tricepsand subscapular skinfolds. Body fat percentage wasestimated by Siri’s (1993) equation and was used toestimate fat mass (kilograms) and fat-free mass(kilograms). The same investigators performed alltests.

Standing vertical jumping ability. Each participant per-formed vertical jumps on a contact mat (CefiseSports Biotechnology, model Pro, Nova Odessa,Brazil) connected to a computer with Windows XP

operating system. The CounterMovement Jumpwith arm swing was used in order to measure thestanding vertical jumping ability according todescriptions by Breed and Young (2003). A standingdouble foot take-off with a countermovement andarm swing was adopted. The CounterMovementJump was performed starting from a standing posi-tion, then squatting down to a knee angle of 100°and then extending the knee in one continuousmovement. Participants were asked to jump as highas they could three times, and the best performancecalculated by the Jump System Pro software wasreported.

Agility. The shuttle run test (Johnson & Nelson,1986) was used for measuring the agility. Wemarked a distance of 9.14 m on the floor with 2separate pieces of tape. Participants were asked tostart behind the first piece of tape, then after a beeprun and pick up a block (5 cm × 5 cm × 10 cm) onthe opposite tape and bring it to the first tape, com-pleting 2 consecutive 18.38-m lengths for a total of37.16 m. The chronometer was stopped when theathlete crossed the start line with the second block.Three attempts were performed and the best result(less time spent on test execution) was used fordetermining agility.

Functional evaluation. The Yo–Yo endurance test(Level 1) was performed for estimating maximaloxygen consumption (VO2max) (ml · min−1 · kg−1)according to descriptions by Bangsbo, Iaia, andKrustrup (2008). The athletes should run betweentwo lines demarcated and separated by a distanceof 20 m, turning when signalled by the recordedbeeps. After each minute or so, the pace getsquicker. If the line is not reached in time theparticipant must run to the line turn and try tocatch up with the pace within 2 more “beeps”.The test is stopped if the participant fails tocatch up with the pace within the two ends. Theathlete’s score is the total distance covered beforethey were unable to keep up with the recording.The following formula was used for estimatingVO2max: VO2max (ml · min−1 · kg−1) = distance(m) × 0.0084 + 36.4 (Bangsbo et al., 2008).

Upper respiratory symptoms episodes. Upper respiratorysymptoms episodes in the adolescent athletes weremonitored using daily log books. Participants wererequested to record their daily symptoms of upperrespiratory symptoms (including runny nose, cold,otitis, headache, sore throat, fever, cough, nasalsymptoms and myalgia) throughout the study, inaccordance with descriptions by Tsai, Chou,Chang, and Fang (2011) and Peters, Shaik, andKleinveldt (2010). To minimise over reporting and

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exclude trivial symptoms, only reports of two ormore symptoms that lasted for more than 1 daywere regarded as indicative of the existence ofupper respiratory symptoms. Also, a new episodewas considered after a minimum interval of 7 daysfollowing the previous one.

Blood collection and analysis. Blood samples were col-lected from athletes at four moments during thetraining season. All blood collections were obtainedfrom the antecubital vein and collected intoVacutainer® tubes (Becton Dickinson Ltd, Oxford,UK) after a 12-h overnight fasting and a 72-h periodof rest after the last training session or competition atthe same time point (between 07:00 and 08:00 am).All blood was collected, processed, and centrifuged(20 min at 1400 rpm at 18°C). Plasma and serumaliquots were stored at −80°C for subsequent bio-chemical analysis.

Total leukocyte counts and leukocyte subsets weremeasured using an automated cell counter (BXMicros 60 – CT; ABX Diagnostics, Irvine, CA,USA) and the results were presented in terms ofcell number × mm3.

Plasma cytokine assay. Tumour necrosis factor-alpha,interleukin-6, interleukin-10 and C-reactive proteinwere determined in duplicate by enzyme-linkedimmunosorbent assay, following the specificationsof manufacturer (Quantikine High Sensitivity Kit;R&D Systems, Minneapolis, MN, USA). Theintra-assay, inter-assay and sensitivity were as fol-lows: 5.2%, 7.4% and 1.6 pg · ml−1 for tumournecrosis factor-alpha; 7.8%, 7.2% and 0.039 pg ·ml−1 for interleukin-6; 5%, 7.3% and 3.9 pg · ml−1

for interleukin-10; and 4.4%, 6% and 0.00001 mg ·l−1 for C-reactive protein. The results for tumournecrosis factor-alpha, interleukin-6 and interleukin-10 are presented in terms of picograms per millilitre(pg · ml), and for C-reactive protein the results arepresented in terms of mg · l−1.

Serum hormone assay. Serum cortisol was determinedin duplicate by enzyme-linked immunosorbentassay, following the specifications of the manufac-turer (Quantikine High Sensitivity Kit; R&DSystems, Minneapolis, MN, USA). The intra-assay,inter-assay and sensitivity were 6.3%, 10.4% and0.071 ng · ml−1, respectively. The results are pre-sented in terms of nmol · l−1.

Serum testosterone was determined in duplicateby chemiluminescence, following the specificationsof the manufacturer (Roche Diagnostics, BurgessHill, West Sussex, UK). The intra-assay, inter-assay and sensitivity were 9.3%, 14% and 8 ng ·dl−1, respectively. The results are presented interms of nmol · l−1.

Statistical analyses

The normality of data distribution was determinedusing the Shapiro–Wilk test and the homogeneity ofvariance was evaluated through the Levene test. As ameasure of stabilisation of immunological and hormo-nal variables in the moments before the season (−72 hand Pre-season), we applied the Student’s t-test forpaired samples. To determine the differences betweenthe moments of evaluation in the group analysis, weused the analysis of variance (ANOVA) for repeatedmeasures. When significant differences were revealedby the ANOVA, Tukey’s Post-hoc test was used.

To check the percentage of occurrence of upperrespiratory symptoms episodes between the periods(Preparatory and Competitive), the total number ofpossible occurrence of upper respiratory symptomsin each period (number of participants × number ofweeks in each period) was calculated. Then, thepercentages of occurrence of upper respiratorysymptoms in each period were calculated, based onthe number of occurrences of upper respiratorysymptoms in each period and on the total numberof possible occurrences of upper respiratory symp-toms in each period. Afterwards, the chi-square testwas performed to verify possible differences betweenthe upper respiratory symptoms percentages of eachperiod. The weekly occurrence of upper respiratorysymptoms was expressed in percentage (%) of theaverage of the occurrence of upper respiratory symp-toms during the periods and by a 95% confidenceinterval (95% CI). Differences in the occurrence ofupper respiratory symptoms between periods weredetermined by the chi-square (χ2) test. The Pearsoncorrelation coefficient was used to determine possi-ble relationships between training load and its varia-tions and the upper respiratory symptomsincidences. All data were expressed as mean ± stan-dard deviation. All analyses were performed usingthe software Statistica® Version 6.0. The level ofsignificance was set at P < 0.05.

Results

Table I demonstrates the schematic evaluation of thetraining load indicators. There was a predominanceof functional training for all the sessions during theseason.

There were no significant differences betweenimmunological and hormonal markers at −72 h andPre-season moments (Table II).

Table III demonstrates the comparison for theanthropometric, functional and neuromuscular eva-luations at Pre-season, at the end of the preparatoryperiod (Preparatory) and at the end of the competi-tive period (Competitive). Tukey’s post hoc testindicated significant differences in agility at the

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Competitive moment as compared to the Pre-seasonmoment (P = 0.005), and in estimated VO2max at thePreparatory moment as compared to the Pre-seasonmoment (P = 0.044).

There was a significant difference in the average ofself-reported occurrence of upper respiratory symp-toms at the preparatory period (28.8% [CI95%19.3–40.5%]) as compared to the competitive period

Table II. Comparison of immunological and hormonal markers in adolescent basketball athletes at −72 h before the start of the season andat the pre-season moment.

Variable −72 h Pre-season P

Cortisol (nmol · l−1) 213.35 ± 81.82 187.04 ± 71.20 0.2477Testosterone (nmol · l−1) 15.99 ± 4.64 14.96 ± 4.27 0.1823Interleukin-6 (pg · ml−1) 1.90 ± 0.33 1.68 ± 1.01 0.3739Interleukin-10 (pg · ml−1) 11.88 ± 6.68 11.02 ± 7.06 0.4769Tumour necrosis factor-alpha (pg · ml−1) 5.68 ± 3.09 4.84 ± 2.67 0.4235C-reactive protein (mg · l−1) 0.66 ± 0.87 0.74 ± 0.87 0.9998Total leukocytes (cell · mm−3) 7054.55 ± 1320.12 6518.18 ± 1129.44 0.3983Neutrophils (cell · mm−3) 3615.64 ± 551.26 3485.55 ± 776.99 0.7896Monocytes (cell · mm−3) 443.00 ± 67.61 413.55 ± 80.65 0.4235Lymphocytes (cell · mm−3) 2868.18 ± 827.99 2564.00 ± 660.82 0.7221

Table I. Schematic evaluation of the load, strain and monotony in adolescent basketball athletes throughout a sports season.

Objectives of the training (%)

Period Weeks Technical Functional Weekly mean load (a.u.) Strain (a.u.) Monotony (a.u.)

Preparatory 1 38.0 62.0 631 6021 3.182 30.0 70.0 529 4331 2.733 27.0 73.0 631 6028 3.184 25.0 75.0 674 6154 3.045 37.0 63.0 397 3360 2.826 16.0 84.0 660 5261 3.99

Competitive 7 31.0 69.0 768 6685 2.908 23.0 77.0 645 5961 3.089 19.0 81.0 651 7270 3.72

10 20.0 80.0 636 8181 4.2911 18.0 82.0 740 9324 4.2012 16.0 84.0 607 3570 2.9413 17.0 83.0 611 8700 3.5614 19.0 81.0 333 1505 1.5115 20.0 80.0 649 8888 4.5716 21.0 79.0 447 5359 4.0017 27.0 73.0 650 6406 3.2818 24.0 76.0 811 12860 5.2819 25.0 75.0 644 8246 4.2720 23.0 77.0 569 6406 3.75

Table III. Anthropometric, functional and neuromuscular evaluations in adolescent basketball athletes at different moments of a basketballseason.

Variable Pre-season Preparatory Competitive

Age (years) 13.32 ± 0.60 13.63 ± 0.60 13.95 ± 0.40Body mass (kg) 62.96 ± 9.70 63.21 ± 9.40 63.24 ± 8.20Height (cm) 171.90 ± 4.70 172.50 ± 9.40 174.18 ± 4.50Body fat (%) 19.15 ± 9.30 17.46 ± 8.20 15.35 ± 6.50CounterMovement Jump (cm) 34.10 ± 5.00 39.24 ± 6.50 40.30 ± 6.30Agility (seg) 11.13 ± 0.70 10.51 ± 0.70 10.25 ± 0.30*Estimated VO2max (ml · kg−1 · min−1) 34.84 ± 6.10 40.80 ± 6.00* 40.50 ± 4.60

Notes: *Significant difference as compared to the Pre-season moment. CMJ = CounterMovement Jump. Mean ± standard deviation(P < 0.05).

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(61.7%, [CI95% 53.8–68.9%]) (χ2 = 20.03, d.f. = 1,P < 0.0001) (Figure 2).

There were significant increases in plasma con-centrations of tumour necrosis factor-alpha and C-reactive protein at the Competitive moment as com-pared to the Pre-season (P = 0.0001, P = 0.0017,respectively) and as compared to the Preparatorymoment (P = 0.0001, P = 0.0119, respectively). Inaddition, serum concentration of interleukin-6demonstrated significantly elevated at theCompetitive moment as compared to thePreparatory (P = 0.0015) Also, there was a signifi-cant decrease in interleukin-10 at the Competitivemoment as compared to the Pre-season (P = 0.0077)(Figure 3).

There was a significant increase in plasma concen-trations of cortisol at the Competitive moment ascompared to the Pre-season (P = 0.0002) and ascompared to the Preparatory moment (P =0.0425). There were no significant changes forplasma concentration of testosterone throughoutthe season. Also, there was a significant decrease inthe T/C ratio at the Competitive moment as com-pared to the Pre-season (P = 0.0004) (Figure 4).

There was a significant correlation betweenmonotony and the occurrence of upper respiratorysymptoms (r = 0.48, P < 0.05) throughout the sea-son (Figure 5). Furthermore, there were no signifi-cant correlations between occurrence of upperrespiratory symptoms and both weekly mean load(r = 0.20) and strain (r = 0.40).

Post hoc tests revealed significant increases inneutrophils at the Competitive moment as comparedto the Preparatory (P = 0.0490) and in monocytes atthe Competitive moment as compared to the Pre-season (P = 0.0054) (Table IV).

Discussion

The aim of the present study was to monitor thehormonal and immunological responses and the

incidence of episodes of upper respiratory symptomsin adolescent athletes during different stages of thesports season. The present results suggest that peri-ods of training plus competitive games could inducea pro-inflammatory and catabolic environment inadolescent athletes, which was supported by the sig-nificant increase in pro-inflammatory cytokines andstress hormones such as tumour necrosis factor-alpha, C-reactive protein and cortisol. In addition,the occurrence of episodes of upper respiratorysymptoms was significantly higher during theCompetitive period as compared to the Preparatoryperiod of the season, confirming our initial

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Figure 3. Serum concentrations of cytokines in adolescent athletesat different moments of a basketball season.Notes: IL-6 = interleukin-6; IL-10 = interleukin-10; TNF-alpha =tumour necrosis factor-alpha; CRP = C-reactive protein.*Significant difference as compared to the Pre-season moment.#Significant difference as compared to the Preparatory moment.Mean ± standard deviation (P < 0.05).

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hypothesis. Moreover, these inflammatory and cata-bolic environments observed at the end of the com-petitive apparently did not affect neuromuscular andfunctional performances. In conclusion, the present

results provide evidence that this increased occur-rence of episodes of upper respiratory symptomsexperienced by the adolescent athletes during thecompetitive stage may be due to the unwantedeffects of an inflammatory process in response tomuscle micro-trauma caused by excessive stress oftraining and/or competition.

The upper respiratory symptoms are generallyaccepted as the most common medical conditionaffecting athletes, mainly during periods of hardtraining and competition (Gleeson, 2007; Heat,Macera, & Nieman, 1992; Nieman, 1994).However, similar research on interactions betweenperiods of a sports season and the occurrence ofupper respiratory symptoms in adolescent athletes,especially in team sports, are very limited. Hensonet al. (2001) observed that adolescent tennis athletes(14–18 years old) did not demonstrate a significantincrease in the occurrence of upper respiratorysymptoms during a hard period of training whencompared to a non-athlete control group (4.2 ± 1.2and 6.6 ± 1.1, respectively). On the other hand,Novas, Rowbottom, and Jenkins (2003) observed ahigh incidence of upper respiratory symptoms inadolescent and youth tennis players (14–21 yearsold) during a period of hard training and competi-tion. The present study found a significant increase(38%) in the occurrence of upper respiratory symp-toms in adolescent basketball athletes during thecompetitive period of a sports season, which is inaccordance with the results found by Novas et al.(2003) and other studies performed on youth volley-ball (Dias et al., 2011) and swimming (Rama et al.,2013) athletes, suggesting that periods of trainingand competition can increase the occurrence ofupper respiratory symptoms when compared to thepreparatory period of a season, even in adolescentathletes.

Another result found in our study was a significantcorrelation between monotony and the occurrence ofupper respiratory symptoms (r = 0.48; P < 0.05)throughout the sports season. The monotony,understood as an index of the training variability(Foster, 1998), was also moderately correlated tocases of upper respiratory symptoms in the study ofPlutur et al. (2004), where the authors found that53–64% of cases of upper respiratory symptomswere associated with earlier increases in the monot-ony. In this sense, our findings and the results foundby Plutur et al. (2004) may suggest the usefulness ofthis variable as an instrument to detect which ado-lescent athlete could be more prone to occurrencesof upper respiratory symptoms during a sports sea-son. Thus, monitoring of these variables may beuseful for coaches and trainers to help implementthe proper training loads during a season. Theyneed to be aware of the trends that follow when

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Figure 4. Serum concentrations of hormones in adolescent ath-letes at different moments of a basketball season.Notes: *Significant difference as compared to the Pre-seasonmoment. #Significant difference as compared to the Preparatorymoment. Mean ± standard deviation (P < 0.05).

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Figure 5. Correlations between monotony and self-reportedoccurrence of upper respiratory symptoms in adolescent athletesduring a basketball season (r = 0.48, P < 0.0001).Note: URS = upper respiratory symptoms.

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episodes of upper respiratory symptoms (that couldlead to the presence of negative adaptations to train-ing and/or decreases in performance) are most likelyto occur.

Moreover, Nieman (1994) suggested that inten-sive efforts can increase the risk of occurrence ofupper respiratory symptoms in athletes due to nega-tive changes in immune function and elevated stresshormones such as cortisol. Additionally, Morgadoet al. (2012) observed that long-term intensive train-ing may affect the function of innate immune cells inyoung athletes by reducing the ability of monocytes,neutrophils and dendritic cell subsets to producecytokines such as interleukin-6, tumour necrosis fac-tor-alpha and interleukin-1, thus indicating areduced capacity of the innate immune to respondto acute challenges. In fact, to counteract theunwanted effects of an inflammatory process, theimmune system produces anti-inflammatory factors(such as interleukin-10) that, in response to exces-sive inflammation, persist for long periods and mayresult in immune suppression (Dinarello, 1992;Morgado et al., 2012). In our study, serum concen-trations of cortisol, tumour necrosis factor-alpha, C-reactive protein and the total count of monocytesand neutrophils were elevated after the end of thecompetitive period, however, serum concentrationsof interleukin-10 decreased at the same time point,suggesting that the increased occurrence of episodesof upper respiratory symptoms observed during thecompetitive period could be a result of the unwantedeffects of an inflammatory process in our adolescentathletes.

Also, it is well known that periods of intensivetraining and/or competition can induce acute localinflammatory responses in working skeletal musclethat may evolve into chronic inflammation and pro-duce systemic inflammation by increasing serumconcentrations of pro-inflammatory cytokines suchas interleukin-6, tumour necrosis factor-alpha andinterleukin-1β (Jürimäe et al., 2011). This pro-inflammatory and catabolic state has been suggestedto be the contributing factor of possible overtrainingthat can impair performance (Smith, 2000).Although inflammatory markers have increased atthe end of the competitive period as compared to

preparatory, we did not find any alteration in thefunctional and neuromuscular evaluations, suggest-ing only a process of adaptation of our adolescentathletes in response to the demands of training andcompetition. In fact, other studies suggest that lowerlevels of pro-inflammatory cytokines (like interleu-kin-6 and tumour necrosis factor-alpha) resultingfrom exercise may contribute to the body’s abilityto respond effectively to a variety of stressors, such astissue injury (Zaldivar et al., 2006), and may actuallypromote growth of muscle and blood vessels andserve as a beneficial response to exercise (Mccourt,Wang, Sookhai, & Redmond, 1999; Nemet et al.,2004; Pedersen et al., 2003).

One limitation of this study is the absence of anadequate control group, although we can consider theathletes in our study as their own controls, becausethey were studied before the start of the season, aswell as the fact that they had prior experience with thephysical tests performed in this study. Moreover, dueto the specific population studied (adolescent ath-letes) as well as the difficulty of controlling the dailyphysical activities and avoiding possible discrepantresults due to a non-homogeneous control group,we chose to perform a blood collection 72 h beforethe start of the season, as a measure of stabilisation ofthe biochemical variables. Thus, we believe we arepresenting the baseline of adolescent athletes forthese markers, since volunteers did not perform anykind of physical activity in the period between thecollection −72 h and Pre-season, as well as no occur-rence of upper respiratory symptoms was observedduring this period. Another study (Nemet et al.,2004) accompanying the same population of athleteswithout the presence of a control group, also observedchanges in some systemic inflammatory markers andhormone resulting from loads of training and compe-tition periods similar to those used in the presentstudy. Likewise, other studies that proposed monitor-ing the immune responses and the occurrence ofupper respiratory symptoms during periods of asports season also observed that the control groupshowed no changes and/or increased occurrence ofupper respiratory symptoms during the experimentalperiod (Henson et al., 2001; Morgado et al., 2012;Rama et al., 2013).

Table IV. Total leukocyte counts and leukocyte subsets in adolescent athletes at different moments of a basketball season.

Pre-season Preparatory Competitive

Total Leukocytes (cell · mm−3) 6518.18 ± 1129.44 6327.27 ± 1107.33 8154.54 ± 2785.45Neutrophils (cell · mm−3) 3485.54 ± 776.99 3256.64 ± 628.38 4649.18 ± 2055.50#

Monocytes (cell · mm−3) 413.55 ± 80.66 517.73 ± 136.33 610.36 ± 173.70*Lymphocytes (cell · mm−3) 2564.00 ± 660.82 2425.00 ± 640.84 2720.64 ± 747.62

Notes: *Significant difference as compared to the Pre-season moment. #Significant difference as compared to the Preparatory moment.Mean ± standard deviation (P < 0.05).

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In conclusion, the results of this study suggest thatperiods of training and competition can increase theoccurrence of upper respiratory symptoms whencompared to the preparatory period of a season,even in adolescent athletes. Since these increasedoccurrences of upper respiratory symptoms couldsuggest that some aspects of the immune systemare depressed (which may indicate a state of over-reaching/overtraining in which performance is tem-porarily reduced), our results provide evidence thatthis increased occurrence of upper respiratory symp-toms experienced by adolescent athletes during thecompetitive period may be due to the unwantedeffects of an inflammatory process in response tomuscle micro-trauma caused by excessive stress oftraining and competition. Moreover, these inflam-matory and catabolic states observed at the end ofthe competitive stage apparently did not affect neu-romuscular and functional performances. However,whether this is a necessary process of adaptation toincreased physiological stress or due to a reducedability of the immune system to respond againstepisodes of upper respiratory symptoms is stillinconclusive. Thus, according to Concepcion-Huertas et al. (2013), the analysis of the relationshipbetween pro-inflammatory cytokines and musclerepair/damaging effects of exercise, especially in ado-lescent athletes who are seeking to build a solidcareer in a particular sport, should be further ana-lysed so as to assess the beneficial versus harmfuleffects of inflammation during a sports season.

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