Thesis (MScSportSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The purpose of this qualitative-quantitative study was to describe the exercise intensity and
predictors of performance of a multi-stage mountain bike (MTB) race (2014 Absa Cape Epic)
lasting 8 days. Twenty-three amateur mountain bikers (age 39 ± 9 years, height 178.8 ± 8.2
cm, body mass 74.7 ± 9.1 kg, VO2max 54 ± 7 ml.kg-1.min-1) who completed the 2014 Absa
Cape Epic were involved in the study. The participants were divided into two groups
according to their MTB experience. The experienced group included participants who
previously completed more than three 3-day multi-stage MTB events and the novices group
included those who has completed less than 3-day multi-stage MTB events.
Prior to the event the participants completed a maximal aerobic cycling test and a simulated
40 km time trial (TT). The maximal aerobic test was used to determine 3 work intensity
zones based on heart rate (HR) corresponding to blood lactate thresholds (LT: increase in
blood lactate concentration of 1 mmol.l-1 above baseline values and the onset of blood
lactate accumulation (OBLA), a fixed blood lactate concentration of 4 mmol.l-1). There were
no statistically significant differences in the physical, physiological and performance
variables measured in the laboratory between the two groups. The exercise intensity during the Cape Epic was measured using telemetric HR monitoring
sets. RPE values were noted after each stage of the race. The mean HR was 88.1 ± 5.3%
(experienced) and 84.2 ± 11.0% (novices) of maximal HR during the race or 88.9 ± 3.5%
(experienced) and 85.9 ± 10.6 (novices) of laboratory determined maximum HR. More time
was spent in the “low” HR zone (43.1 % vs 58.5 %, respectively), while only a small amount
of time was spent in the “hard” HR zone (7.4% and 6.1%, respectively). The experienced
group spent statistically significantly more time in the “moderate” HR zone compared to the
novices group (49.5 % vs. 35.4 %). The experienced group performed significantly better
during the event compared to the novices group in both the total event time (P = 0.004) and
the general classification (P = 0.01).
Relative and absolute power output (PO) at OBLA (P = 0.01 and 0.02, respectively) were
statistically significant predictors of total event time, while relative peak power output was a
significant predictor of general classification for the event (P = 0.02) . The total TT time was
a significant predictor of average event HR (P = 0.03). This study showed that this MTB stage race is physiologically very demanding and requires
cyclists to have excellent endurance capacity, as well as strength and power. The
parameters from the maximal aerobic capacity test correlated better with outdoor
performance than parameters from the simulated 40 km TT. Therefore the standard
maximal aerobic capacity test are sufficient for testing mountain bikers and sport scientists
can continue using this test to prescribe exercise intensity zones for training and events. / AFRIKAANSE OPSOMMING: Die doel van hierdie kwalitatiewe-kwantitatiewe studie was om die oefeningsintensiteit en
voorspellers van prestasie tydens ‘n multi-dag bergfiets kompetisie (Absa Cape Epic) van 8
dae lank te bepaal. Drie-en-twintig bergfietsryers (ouderdom 39 ± 9 jaar, lengte 178.8 ± 8.2
cm, liggaamsmassa 74.7 ± 9.1 kg, VO2maks 54 ± 7 ml.kg-1.min-1) wat die 2014 Absa Cape
Epic voltooi het, het aan die studie deelgeneem. Die deelnemers is in twee groepe verdeel
volgens hulle ervaring in multi-dag bergfiets kompetisies. Die ervare groep was al die
deelnemers wat meer as drie 3-dae multi-dag bergfiets kompetisies voltooi het. Die onervare
groep was al die deelnemers wat minder as drie 3-dag multi-dag bergfiets kompetisies
voltooi het.
Voor die kompetisie het al die deelnemers ‘n maksimale aërobiese toets en ‘n gesimuleerde
40 km tydtoets in die laboratorium voltooi. Die maksimale aërobiese toets is gebruik om drie
werk intensiteit sones volgens die hartspoed te bepaal, naamlik die hartspoed by die
laktaatdraaipunt(‘n toename in bloed [laktaat] van 1 mmol.l-1 bo die basislynwaardes) en die
hartspoed by die aanvang van bloedlaktaat akkummulasie (‘n vaste bloed [laktaat] waarde
van 4 mmol.l-1). Daar was geen statisties betekenisvolle verskille in die fisiese, fisiologiese
en prestasie veranderlikes tussen die twee groepe nie.
Die oefeningsintensiteit tydens die Cape Epic was gemeet deur gebruik te maak van
hartspoedmonitors. Die RPE waardes was aan die einde van elke skof genoteer. Die
gemiddelde hartspoed was 88.1 ± 5.3 % (ervare) en 84.2 ± 11.0 % (onervare) van
maksimale kompetisie hartspoed, of 88.9 ± 3.5 % (ervare) en 85.9 ± 10.6 % (onervare) van
die maksimale hartspoed soos in die laboratorium gemeet. Die fietsryers het meer tyd spandeer in die “lae” hartspoed sone (43.1 % vs 58.5 %,
onderskeidelik), in vergelyking met die “moeilike” hartspoed sone (7.4 % vs 6.1 %,
onderskeidelik). Die ervare groep het statisties betekenisvol meer tyd in die “matige”
hartspoed sone spandeer (49.5 % vs. 35.4 %) in vergelyking met die onervere groep. Die
ervare groep het beter presteer tydens die kompetisie vir beide totale kompetisie tyd (P =
0.004) en algehele klassifikasie (P = 0.01).
Relatiewe en absolute krag by aanvang van bloed laktaat akkumulasie was statisties
betekenisvolle voorspellers van totale kompetisie tyd (P = 0.01 en 0.02, onderskeidelik),
terwyl maksimale krag ‘n statisties betekenisvolle voorspeller was van algehele klassifikasie
in die kompetisie (P = 0.02). Die totale tydtoets tyd was ‘n statisties betekenisvolle
voorspeller van gemiddelde hartspoed tydens die kompetisie. Die studie het gewys dat hierdie multi-dag bergfiets kompetisie fisiologies baie uitdagend is
en dat fietsryers uistekende uithouvermoë kapasiteit, sowel as krag en plofkrag moet besit.
Die veranderlikes van die maksimale aërobiese toets het beter met prestasie in die veld
gekorreleer as die veranderlikes van die gesimuleerde 40 km tydtoets. Daar word dus
afgelei dat die standaard maksimale aërobiese toets voldoende is vir die toetsing van
bergfietsryers en sportwetenskaplikes kan aanhou om hierdie toets te gebruik om
oefeningsintensiteit sones voor te skryf vir oefensessies en kompetisies.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/95970 |
| Date | 12 1900 |
| Creators | Greeff, Marli |
| Contributors | Terblanche, Elmarie, Stellenbosch University. Faculty of Education. Dept. of Sport Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 128 p. |
| Rights | Stellenbosch University |
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