Substrate use and biochemical response to a 3,211-km bicycle tour in trained cyclists

Dustin R. Slivka, Charles L. Dumke, Walter S. Hailes, John S. Cuddy, Brent C. Ruby

Research output: Contribution to journalReview article

11 Citations (Scopus)

Abstract

The purpose of this study was to assess the physiological adaptations in physically fit individuals to a period of intensified training. Ten trained males cycled outdoors ∼170 km day-1 on 19 out of 21 days. Expired gas was collected on days 1 and 21 during maximal graded exercise and used for the determination of gross efficiency and whole body substrate use. Muscle biopsies were obtained before and after exercise on days 2 and 22 for the determination of mtDNA/gDNA ratio, gene expression, metabolic enzyme activity and glycogen use. Muscle glycogen before and after exercise, fat oxidation, and gross efficiency increased, carbohydrate oxidation decreased (p<0.05), and VO 2max did not change over the 21 days of training. Citrate synthase (CS), -hydroxyacyl CoA dehydrogenase (-HAD) and cytochrome c oxidase (COX) enzyme activity did not change with training. CS and -HAD mRNA did not change with acute exercise or training. COX (subunit IV) mRNA increased with acute exercise (p<0.05) but did not change over the 21 days. PGC-1α mRNA increased with acute exercise, but did not increase to the same degree on day 22 as it did on day 2 (p<0.05). UCP3 mRNA decreased with training (p<0.05). Acute exercise caused an increase in mitofusin2 (MFN2) mRNA (p<0.05) and a trend for an increase in mtDNA/gDNA ratio (p = 0.057). However, training did not affect MFN2 mRNA or mtDNA/gDNA ratio. In response to 3,211 km of cycling, changes in substrate use and gross efficiency appear to be more profound than mitochondrial adaptations in trained individuals.

Original languageEnglish (US)
Pages (from-to)1621-1630
Number of pages10
JournalEuropean Journal of Applied Physiology
Volume112
Issue number5
DOIs
StatePublished - May 1 2012

Fingerprint

Messenger RNA
Exercise
Mitochondrial DNA
Citrate (si)-Synthase
Glycogen
Oxidoreductases
Physiological Adaptation
Muscles
Electron Transport Complex IV
Enzymes
Coenzyme A
Gases
Fats
Carbohydrates
Biopsy
Gene Expression

Keywords

  • Cycling
  • Efficiency
  • Gene expression
  • Metabolic enzymes
  • MtDNA
  • Training adaptation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)

Cite this

Substrate use and biochemical response to a 3,211-km bicycle tour in trained cyclists. / Slivka, Dustin R.; Dumke, Charles L.; Hailes, Walter S.; Cuddy, John S.; Ruby, Brent C.

In: European Journal of Applied Physiology, Vol. 112, No. 5, 01.05.2012, p. 1621-1630.

Research output: Contribution to journalReview article

Slivka, Dustin R. ; Dumke, Charles L. ; Hailes, Walter S. ; Cuddy, John S. ; Ruby, Brent C. / Substrate use and biochemical response to a 3,211-km bicycle tour in trained cyclists. In: European Journal of Applied Physiology. 2012 ; Vol. 112, No. 5. pp. 1621-1630.
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