doctoral thesis
Iva Jurov (Author), Samo Rauter (Mentor), Nicola Keay (Co-mentor)

Abstract

The main issue about energy availability in male athletes still remains poorly understood: when does the low energy availability (LEA) appear and what effects does it have on performance? We aimed to address this question with a strictly controlled intervention study with randomised order of three step energy availability reduction (reduction of 25%, 50% and 75%) in trained and well-trained male endurance athletes. This study modulated participants’ exercise energy expenditure and controlled energy intake and consequently manipulated energy availability in three progressive stages, set to determine potential effects of LEA. All parameters were strictly measured to prevent any error in estimation of energy availability. Performance was measured with three specific tests for explosive power, endurance and agility. Blood was drawn, resting energy expenditure was monitored and two questionnaires were repetitively used to address any changes in eating behaviours and well-being. Repeated measured design showed poorer performance (power output p=.001, relative power output p=.018, explosive power p=.000, lactate concentration p=.001,), the quartile range for testosterone was lower (p=.026), there was a tendency for lower T3 (p=.072). Eating behaviours and well-being were worse (p=.011 and p=.002). The intervention also resulted in lower body fat (p=.013). Based on the results we concluded that the threshold for LEA in men is much lower than 30 kcal/kg FFM/day. We propose using a spectre of 9-25 kcal/kg FFM/day. Reducing energy availability impairs explosive power first, then endurance. It is associated with a reduction in testosterone, T3 and possibly in IGF-1, but hormones are more resilient to changes in energy availability. Psychological assessment of eating behaviours and well-being proved to be very useful, whereas monitoring resting energy expenditure did not.

Keywords

energy availability;relative energy deficiency syndrome;endurance;male atletes;performance;

Data

Language: English
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UL FŠ - Faculty of Sport
Publisher: [I. Jurov]
UDC: 796.012-055.1:620.926(043.3)
COBISS: 98638595 Link will open in a new window
Views: 284
Downloads: 34
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Other data

Secondary language: Slovenian
Secondary title: Določanje meje nizke energijske razpoložljivosti pri treniranih vzdržljivostnih športnikih
Secondary abstract: O nizki energijski razpoložljivosti je znano vedno več, vendar še vedno ne vemo, kdaj se pojavi pri moških in kako učinkuje na telesno zmogljivost. Raziskava te doktorske disertacije je bila usmerjena v reševanje tega problema. Zasnovali smo raziskavo, ki je bila strogo nadzorovana. Gre za interventno študijo z randomiziranim zaporedjem zniževanja energijske razpoložljivosti v treh stopnjah (za 25, 50 in 75 %), ki je potekala na treniranih in zelo treniranih vzdržljivostnih moških športnikih. Zniževanje energijske razpoložljivosti smo dosegli tako, da smo strogo nadzorovali energijske vnose ter v treh stopnjah povečevali energijsko porabo ob telesni vadbi, tako da je ta ustrezala izračunani energijski razpoložljivosti. Ugotavljaji smo učinke nizke energijske razpoložljivosti. Zmogljivost smo merili s tremi športno specifičnimi testi za merjenje explozivne moči, vzdžljivosti in agilnosti. Športnikom smo vzeli kri, izmerili energijsko porabo v mirovanju in večkrat uporabili dva vprašalnika za oceno prehranjevalnih navad in dobrega počutja. Rezultati so pokazali, da z zniževanjem energijske razpoložljivosti dosežemo nižjo zmogljivost (moč p=.001, moč izražena glede na telesno maso p=.018, eksplozivna moč p=.000, koncentracija laktata p=.001,), znižani kvartil vrednosti testosterona (p=.026), obstaja tendenca za znižane vrednosti trijodtironina (p=.072). Prehranjevalne navade in splošno počutje sta slabša (p=.011 in p=.002). Intervenca je povzročila tudi znižan delež maščobe (p=.013). Meja za nastanek nizke energijske razpoložljivosti je precej nižja kot pri ženskah. Predlagamo uporabo spektra 9-25 kcal/kg puste telesne mase/dan. Zniževanje energijske razpoložljivosti najprej zmanjša eksplozivno moč, nato vzdržljivost. Povezano je z znižanim testosteronom, trijodtironinom in verjetno z znižanim IGF-1, opažali pa smo, da so hormoni manj občutljivi na zniževanje energijske razpoložljivosti. Psihološka ocena prehranjevalnih navad in dobrega počutja se je izkazala za zelo uporabno glede na spremembe energijske razpoložljivosti, česar nismo ugotavljali tudi za meritev energijske porabe v mirovanju.
Secondary keywords: šport;moški;sindrom relativnega energijskega primanjkljaja;telesne sposobnosti;eksplozivna moč;vzdržljivost;agilnost;meritve;testi;vprašalnik;prehrana;hormonski sisstem;Športniki;Disertacije;Energijska razpoložljivost;
Type (COBISS): Doctoral dissertation
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: University of Ljubljana, Faculty of sport
Pages: XVI, 160 f.
ID: 14047836