Senior Honors Projects, 2010-current

Date of Award

Spring 2015

Document Type

Dissertation/Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Kinesiology

Advisor(s)

Michael J. Saunders

Abstract

PURPOSE: To study the influences of carbohydrate intake (CHO) on pacing in endurance cycling, as well as the effects of wearing metabolic headgear (HG) on power output. METHODS: Eight male endurance trained cyclists completed 120 min of constant load cycling at 55% Wmax, immediately followed by a simulated 30 km time trial, on two occasions. On one occasion, subjects consumed a CHO solution at regular intervals throughout the trial, while a placebo (PL) was consumed during the other trial (in a randomly counterbalanced design). For statistical analysis, the 30 km time trial was divided into 4 segments (S1 = 0-7.5 km, S2 = 7.5-15 km, S3 = 15-22.5 km, and S4 = 22.5-30 km), with each segment immediately preceded by a beverage feeding. Further, each of these segments was sub-divided into early (EP) and late phases (LP). Power output (PO) was averaged for three-minute periods in each phase. In addition, PO was calculated for two five-minute periods during the time trial, when HG was worn (starting at 12 km) and not worn (starting at 20 km). RESULTS: In the 30 km time trial (both CHO and PL conditions), PO decreased significantly between S1 (240 ± 13) and S2 (227 ± 11) (p = 0.019), and decreased further during S3 (216 ± 11) (p = 0.017). Subsequently, PO increased between S3 and S4 (234 ± 12) (p = 0.001), resulting in values in S4 which were not significantly different from S1 (p = 0.302). CHO ingestion resulted in significantly greater PO during the trial, versus PL (242 ± 10 W vs 217 ± 14 W; p = 0.044). In the CHO trial, PO did not decrease significantly across the four time segments (p>0.05), whereas in the PL trial PO decreased significantly from S1 to S2 (p = 0.008) and from S2 to S3 (p = 0.009), followed by a subsequent increase in PO between S3 and S4 (p = 0.001). PO was not significantly different between the early and late phase following beverage consumption (230 ± 12 W vs 229 ± 12 W; p = 0.709). There was no significant effect of HG on PO (HG = 216 ± 10 W, no HG = 221 ± 11 W; p = 0.299). CONCLUSION: CHO ingestion improved endurance performance and influenced pacing in a general manner, by preventing decreases in PO over the first three quarters of the time trial. However, the ergogenic effects of CHO were not systematically different between early and late periods following each feeding. In addition, wearing headgear to measure metabolic measurements during exercise did not affect PO.

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