Endocrine response to small-sided games and match play in elite u19 South African soccer players

de Waal, Simon Jake (2017-03)

Thesis (MScSportSc)--Stellenbosch University, 2017

Thesis

ENGLISH ABSTRACT : Purpose Small-sided games (SSGs) are used worldwide with the intention of stimulating significant physiological adaptations in players that are specific to match demands. The external load of SSGs and matches in soccer is well documented, but far fewer studies are aimed at measuring the internal response to these activities. The endocrine response to SSGs and matches in soccer is less well known although the respective hormones; cortisol, testosterone and dehydroepiandrosterone (DHEA) provide a valid measure of training load and total stress in several other methods of exercise. This study aimed to measure the internal endocrine response to training and matches and identify any variations between playing position and whether SSGs were preparing the players for match demands. Methods 22 elite male soccer players (16 – 23 years old), divided into positional subcategories of goalkeeper (n = 4), defender (n = 7), midfielder (n = 5), and attacker (n = 6) provided saliva samples; at rest, in response to 11v11, 7v7, and 4v4 SSGs, friendly and competitive matches, and a yoyo level two intermittent endurance test (YoyoII). Cortisol, testosterone, T:C, and DHEA concentrations were analysed using an ultra-high-performance liquid chromatographic method with mass spectrometric detection in response to small-sided games and matches. Statistically, hormones were analysed through one and two way ANOVA’s to compare different time points and positions. Results Cortisol (ng/ml) increased significantly (0,70 ± 0,40 SD to 3,94 ± 3,26 SD) from resting values in response to competitive match-play immediately after the match amongst the squad as a whole (p < 0.01). Cortisol increased significantly during all small-sided games (p < 0.05). T:C ratio (ng/ml) significantly decreased (0,89 ± 1,93 to 0,19 ± 0,28) from resting values in response to competitive match-play (p < 0.01) while testosterone showed no significant changes in response to match-play. No significant differences were found between the endocrine response of all positional subgroups over any SSGs or matches. DHEA presented no significant changes between all time-points and T:C ratio remained constant throughout the eight month testing period. SSGs presented no significant differences in endocrine response based on the number of players on the field. Yoyo2 produced comparable endocrine response to those at rest amongst the squad as a whole. Conclusions SSGs do not prepare soccer players for matches because they do not stimulate the same stress response than matches. The stress response is likely correlated to more than just physical exertion, therefore cortisol could be used as an indicator of total stress including anxiety and emotional stress as opposed to physical stress alone. Different positions do not result in different internal responses to training and matches regardless of differing external positional requirements. SSGs as a method of training seems to present no risk of overtraining. Future studies should seek to correlate cortisol, testosterone and DHEA with other, more affordable measures of internal training load or be used in conjunction with external training load measures. Future studies should perform repeated testing on smaller study samples due to the high intra-individual variability of endocrine response betweentime-points.

AFRIKAANSE OPSOMMING : Doel Klein-groep spele word algemeen in die wêreld gebruik met die doel om betekenisvolle fisiologiese aanpassings, wat spesifiek tot die vereistes van wedstryde is, by spelers te veroorsaak. Die eksterne lading van klein-groep spele en wedstryde in sokker is goed gedokumenteer, maar baie minder studies poog om die interne response op hierdie aktiwiteite te meet. Endokriene response op klien-groep spele en wedstryde in sokker is nog meer onbekend en tog is dit bekend dat die hormone kortisol, testosteroon en dehidorepiandrosteroon „n geldige meting vir oefenlading en totale stres van verskeie ander oefenmetodes is. Hierdie studie is uitgevoer om die interne, endokriene response op oefening en wedstryde te meet, te bepaal of hierdie ladings tussen speelposisies verskil, en of kliengroep spele die spelers voldoende voorberei vir die eise van wedstryde. Metodes 22 elite sokkerspelers (16 – 23 jaar oud), verdeel in subkategorieë volgens posisies as doelwagter (n = 4), verdediger (n = 7), middelbaanspeler (n = 5), en aanvaller (n = 5), het speekselmonsters tydens rus, in reaksie op 11v11, 7v7, en 4v4 klein-groep spele, „n vriendskaplike en kompeterende wedstryd, asook „n yoyo vlak twee uithouvermoë toets, verskaf. Kortisol-, testosteroon-, testosteroon-kortisol-ratio (T:C), en dehidorepiandrosteroonkonsentrasies (DHEA) is analiseer volgens „n ultra-hoëprestasie vloeistof chromatografiese metode met massaspektrometriese vassteling vir reaksie op klein-groep spele en wedstryde. Statistiese analises is gedoen volgens een- en twee-rigting ANOVAS om die hormone op verskillende tydpunte en tussen verskillende posisies tevergelyk. Resultate Kortisol (ng/ml) het statisties beduidend toegeneem (0,701 ± 0,401 tot 3,938 ± 3,259) vanaf rustende waardes in reaksie op kompeterende wedstryde direk na die wedstryd binne die groep as geheel (p < 0.01). Kortisol het ook statisties beduidend toegeneem in reaksie op al die klein-groep spele (p < 0.05). T:C ratio (ng/ml) het beduidend verlaag (0,891± 1,929 tot 0,193 ± 0,2800) vanaf die rustende waardes in reaksie op die kompeterende wedstryd (p < 0.01), terwyl testosteroon geen beduidende verandering getoon het in reaksie op die wedstryd nie. Geen beduidende verskille is gevind in die endokrienresponse by die verskillende posisies vir al die klein-groep spele of wedstryde nie. DHEA het geen beduidende veranderinge getoon by enige van die tydpunte nie en die T:C ratio het relatief konstant gebly oor die toetsperiode van agt maande. Klein-groep spele, gebaseer op die aantal spelers op die veld, het geen beduidende veranderinge in endokrienresponse meegebring nie. Die Yoyo2 het endokrienresponse meegebring wat vergelykbaar is met die metings van die hele groep tydens rus. Gevolgtrekking Klein-groep spele is moontlik nie die beste manier om sokkerspelers vir wedstryde voor te berei nie, aangesien dit nie dieselfde stresresponse veroorsaak as wedstryde nie. Stresresponse is waarskynlik verwant aan meer as net fisieke inspanning en kortisol kan gebruik word as aanduiding van totale stres, wat angs en emosionele stress insluit, in teenstelling met net fisieke stress. Verskillende speelposisies lei nie noodwendig tot verskillende interne response op oefening en wedstryde nie, ten spyte van die verskillende posisionele eise. Klein-groep spele as oefenmetode hou waarskynlik nie „n risiko vir ooroefening in nie. Toekomstige studies kan kortisol, testosteroon en DHEA met ander meer bekostigbare metodes vir die meet van interne lading vergelyk, of kan gebruik word saam met metings van eksterne ladings. Bykomend, kan toekomstige studies „n kleiner groep deelnemers gebruik, maar meer herhaaldelike metings doen as gevolg van die hoë intraindividuele variasie in endokrienresponse by verskeie tydpunte.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/101025
This item appears in the following collections: