Cooke, CB

King, RFGJ

O'Hara, JP

Seims, A

Thomas, AL

Leeds Beckett Repository

Repeatability of blood glucose responses to intermittent cycling under fasted conditionsBlood glucose concentration during exercise has been shown to influence performance, with studies demonstrating differences in blood glucose after carbohydrate ingestion (Coyle et al 1986: Journal of Applied Physiology, 61, 165-172).  The purpose of this study was to observe the repeatability of blood glucose responses on four separate occasions during intermittent cycling.  Eight well-trained male cyclists (age mean 35.9, s = 7.8 years, body mass mean, 75.5, s = 7.6 kg mean 54.3, s = 3.9 ml.kg-1.min-1) completed 65 minutes of high-intensity cycling [TREK 1400 with SRM power cranks (Jülich, Germany) mounted on a Kingcycle ergometer (High Wycombe, UK)].  The protocol consisted of 20 minutes of incremental exercise, followed by ten 90-second sprints separated by 180-second active recovery (90% and 55% maximum aerobic power output respectively) after an overnight fast, 30 minutes after consumption of a 1l placebo.  Plasma glucose concentration (PGlc) was measured in blood drawn from the anticubital vein before placebo consumption, at rest before exercise, during exercise at the end of each increment and active recovery prior to each sprint.  95% limits of agreement (LOA) for resting, nadir and peak PGlc, and PGlc area under the curve during exercise (AUC) were calculated.Table 1.  PGlc (mmol.l-1) and AUC (mmol.l-1.min) during an intermittent cycling protocol (mean  s), including LOATrial	Resting	Nadir	Peak	AUC1	5.01 0.41	5.30 4.00	7.10 5.20	25.10 36.622	4.99 0.37	5.10 3.90	7.10 4.90	31.14 51.913	5.04 0.37	5.60 3.90	7.60 4.80	26.28 46.864	5.01 0.27	5.20 3.90	7.20 5.10	12.54 32.45LOA	0.54	0.74	1.47	62.27The mean PGlc at rest and during all trials (table 1) was similar (ANOVA, P = 0.962 and 0.291 respectively), a main effect of time was observed with no time-trial interaction (ANOVA, P = 0.012 and P = 0.156 respectively).  PGlc remained stable until the commencement of exercise with no significant difference observed between trials at the nadir and peak values during exercise (ANOVA, P = 0.883 and 0.929 respectively).  The AUC was similar between trials (ANOVA, P = 0.414).  PGlc was less consistent during exercise than at rest with greatest variability at peak PGlc, occurring in intermittent exercise.  The overall PGlc response also exhibited large variability within individuals compared to mean values.  Therefore caution should be exerted when interpreting differences in blood glucose between repeated intermittent exercise trials.  

Repeatability of blood glucose responses to intermittent cycling under fasted conditions

http://eprints.leedsbeckett.ac.uk/id/eprint/1901/1/Repeatability%20BASES%20ABSTRACT%20FINAL.doc

Repeatability of blood glucose responses to intermittent cycling under fasted conditions

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