Hemodynamic changes in recreational cyclists following a long and a short interval high intensity cycling intervention

Basson, Kyle (2019-12)

Thesis (MA)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: The incorporation of high intensity interval training (HIIT) sessions into training plan is becoming increasingly popular due to the multitude of physiological benefits and time efficient nature of the training method. The physiological changes and specific adaptation pathways which follow the different variations of HIIT programmes is not fully understood. It was expected that the short interval HIT programme would be more successful in the improvement of hemodynamics in comparison to the long interval HIT. In addition that the short interval HIT would also improve aerobic and anaerobic ([La] buffering) metabolic performance parameters to a greater extent. The present study used a similar HIIT programme as previously used (Rønnestad et al., 2015). The previously used training programme was adapted to ensure the recreational cyclists (current study) were able to complete the programme. The two HIIT programmes were performed for the same work duration and the same sRPE, to ensure an equal training load (Inoue et al., 2016). In addition, the use of a high RPE simulates the typical intensity that majority athletes train in real world settings (Seiler et al., 2013). The sixteen recreational cyclists who participated in the study were 21.9 (± 2.75) years old, the range was 18 - 27 years. On average, the participants had 5.1 (± 2.92) years cycling experience. The participants trained on average of 7.3 (± 1.94) hours per week between both groups and ranged from four to ten hours a week before the start of the HIIT programme. In the pre-test phase before the HIIT programme, the average participant’s mass was 77.3 ± 7.79kg and the average %BF was 11.0 ± 2.86% at the beginning of the trial. The changes following the two HIIT programmes were assessed through the peripheral blood content (Δ[O2Hb] and Δ[HHb]), the aerobic performance parameters (VO2max, O2 pulse, PPO and PO at OBLA) and lastly the anaerobic parameters were assessed during a repeated Wingate test ([La]max, PPO and %PR). The measurements of the hemodynamic changes were done with the use of near infrared spectroscopy (NIRS). The short interval HIT programme was more effective in the improvement of eight out of the eleven aerobic performance markers in comparison to the long interval HIT programme. The short interval HIT programme improved the Δ[O2Hb] in the periphery during exercise. In contrast, the long interval HIT was more effective in the improvement of increased blood [La] accumulation following training. It was found that the short interval HIT programme showed improvements in the increased O2 availability in the periphery, the changes were suggested to be associated with central adaptations. The long interval HIT showed increased extraction of O2 at OBLA, the improvements were suggested as mostly peripheral adaptations. The findings of the present study suggest that two similar HIIT programmes (which were matched for training load) showed different adaptation pathways provides an explanation for the differences in magnitude of changes seen. The changes associated to central adaptations were more pronounced following the six week training programme than the peripheral adaptations, as peripheral changes require a longer duration of training.

AFRIKAANSE OPSOMMING: ie toevoeging van hoë intensiteitsinterval inoefening (HIIT) sessies tot ʼn inoefeningsplan groei in populariteit as gevolg van die veelvuldige fisiologiese voordele en tyddoeltreffende aard van die oefenmetode. Die fisiologiese veranderinge en spesifieke aanpassings van verskillende variasies van die HIIT-programme, word nie ten volle verstaan nie. Die verwagting sal wees dat ʼn kort interval HITprogram meer suksesvol sal wees as ʼn lang interval HIT-program om hemodinamiese verbetering tot volg te hê. Daarbenewens sal die kort interval HIT ook tot ʼn groter mate aërobiese en anaërobiese ([La] buffer) metaboliese prestasieveranderlikes verbeter. Die huidige studie gebruik 'n soortgelyke HIIT-program soos voorheen gebruik (Rønnestad et al., 2015). Die voorheen gebruikte inoefeningsprogram is aangepas om te verseker dat die rekreasiefietsryers (huidige studie) die program kon voltooi. Die twee HIIT-programme is teen dieselfde werkdsuur en dieselfde sRPE uitgevoer om 'n gelyke oefenlading te verseker (Inoue et al., 2016). Daarbenewens simuleer die gebruik van 'n hoë RPE (8-10) die tipiese intensiteit waarby meerderheidsatlete oefen (Seiler et al., 2013). Die sestien rekreasiefietsryers wat aan die studie deelgeneem het, was 21.9 (± 2.75) jaar oud, die reikwydte was 18-27 jaar. Die deelnemers het gemiddel 5.1 (± 2.92) jaar fietsryervaring gehad. Beide inoefenings groepe het gemiddeld 7.3 (± 1.94) uur per week geoefen, met vier tot tien uur per week voor die aanvang van die HIIT-program. Voor die aanvang van die HIIT-program was die gemiddelde massa van die deelnemers 77.3 ± 7.79kg en die gemiddelde % liggaamsvet 11.0 ± 2.86%. Die veranderinge na aanvang van die twee HIIT-programme was geassesseer deur die perifere bloedinhoud (Δ[O2Hb] en Δ[HHb]), die aërobiese prestasieveranderlikes (VO2max, O2 pulse, PPO en PO by OBLA) en laastens is die anaërobiese veranderlikes geassesseer tydens 'n herhaalde Wingate toets ([La] maksimum, PPO en % PR). Naby infrarooi spektroskopie (NIRS) was gebruik om die hemodinamiese veranderlikes te meet. Die kort interval HIT-program was meer effektief in die verbetering van agt uit die elf aërobiese prestasie merkers in vergelyking met die lang interval HITprogram. ʼn Toename in O2-aflewering was gevind tydens oefening en herstel in die kort interval HITprogram. In teenstelling hiermee was die lang interval HIT meer effektief in die verbetering van verhoogde bloed [La] ophoping na inoefening. Daar is bevind dat die kort interval-HIT-program verbeteringe toon met verhoogde O2-beskikbaarheid in die periferie. Die veranderinge word geassosieer met sentrale aanpassings. Die lang interval HIT het verhoogde ekstraksie van O2 by OBLA getoon, wat geassosieer word met perifere aanpassings. Die bevindings van die huidige studie dui dat die aanpassings van twee soortgelyke HIIT-programme (ooreenstemde oefenlading) deur verskillende meganismes verduidelike kan word. Na die ses weke inoefenings program was die grootste verandering gesien in die sentrale aanpassings as die perifere aanpassings, aangesien perifere veranderinge ʼn langer inoefenings tydperk verg.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/107053
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