Mittuniversitetet

Introduction

While carbohydrate ingestion can improve endurance performance, relatively little is known about the effect of frequency of carbohydrate ingestion. This may be of particular importance in cross-country skiing, where upper-body propulsion is inevitably decreased during drinking periods. Therefore, the study aim was to examine the effect of ingesting carbohydrate at two different frequencies on 30-km cross-country skiing performance.

Methods

Thirteen participants completed four, 30-km classic roller-skiing time-trials on a simulated treadmill course. A 1:1 maltodextrin-fructose solution was provided at high (6 feeds; HF) and low (2 feeds; LF) frequencies and high (2.4 g∙min^-1, 24%;HC) and low (1.2 g∙min^-1, 12%; LC) rates. Gastrointestinal discomfort was measured using an adapted 6-20 Borg scale.

Results

There were no differences in performance between the four trials (140±16, 139±16, 141±18 and 141±18 min for HF-HC, HF-LC, LF-HC and LF-LC, respectively), although LF-LC was likely harmful compared to HF-LC. However, an order effect was apparent (143±17, 140±16, 140±17 and 138±15 min for trials 1-4, respectively). There was a significant rate x frequency interaction for gastrointestinal discomfort, with greater discomfort in LF-HC (10.3±2.7) compared with HF-HC (8.5±3.1) and HF-LC (8.4±2.7). LF-LC (9.0±2.3) was not significantly different to any other trial.

Discussion

These data suggest there is no significant effect of ingestion frequency on 30-km simulated cross-country ski performance. However, there may be a practically relevant detrimental effect of low frequency ingestion at low rates. Further, LF carbohydrate ingestion increases gastrointestinal discomfort when ingested as HC.