Effects of glucose, glucose plus branched-chain amino acids, or placebo on bike performance over 100 km

Klavs Madsen, Dave A. Maclean, Bente Kiens, and Dirk Christensen Department of Physical Education, Odense University, DK-5230 Odense M; and Copenhagen Muscle Research Center, Rigshospitalet, August Krogh Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark Received 14 May 1996; accepted in final form 13 August 1996. Madsen, Klavs, Dave A. MacLean, Bente Kiens, and Dirk Christensen. Effects of glucose, glucose plus branched-chain amino acids, or placebo on bike performance over 100 km. J. Appl. Physiol. 81(6): 2644-2650, 1996. This study was undertaken to determine the effects of ingesting either glucose ( trial G ) or glucose plus branched-chain amino acids (BCAA; trial B ), compared with placebo ( trial P ), during prolonged exercise. Nine well-trained cyclists with a maximal oxygen uptake of 63.1 ± 1.5 ml O 2 · min 1 · kg 1 performed three laboratory trials consisting of 100 km of cycling separated by 7 days between each trial. During these trials, the subjects were encouraged to complete the 100 km as fast as possible on their own bicycles connected to a magnetic brake. No differences in performance times were observed between the three trials (160.1 ± 4.1, 157.2 ± 4.5, and 159.8 ± 3.7 min, respectively). In trial B , plasma BCAA levels increased from 339 ± 28 µM at rest to 1,026 ± 62 µM after exercise ( P