Report

Caffeine improves preloaded cycling but not handcycling 10 km time trial performance

Assessing how levels of caffeine improve preloaded cycling

Lead academic:
Professor Vicky Tolfrey
Funder:
The Peter Harrison Foundation

Low-moderate doses of caffeine (3–6 mg∙kg-1) have been shown to positively influence cycling time trial (TT) performance in able-bodied individuals. During cycling, the leg musculature is the main force producer.

It is debatable whether the findings from such cycling studies are transferable to upper-body exercise (UBE) sports such as kayaking, handcycling and wheelchair sports where the arms produce this force. Caffeine influences the central nervous system by which it acts as an adenosine receptor antagonist to produce motor-activating and arousing effects. With this mechanism in mind, a similar ergogenic benefit could be expected during UBE yet the evidence remains equivocal. 

Methods

  • 11 recreationally active males (age 24±4 y, body mass 85.1±14.6 kg, lower and upper-body VO2peak 42.9±7.3 and 27.6±5.1 mL∙kg∙min-1) participated. Participants attended the laboratory on 8 separate occasions, which consisted of a VO2peak test, a familiarization and 2 (4 mg•kg-1 caffeine and placebo) experimental trials for both cycling and handcycling. The experimental trials consisted of a preload at 65% mode-specific VO2peak, 5 min recovery and a 10 km TT.

Main findings and applications

  • Caffeine improved preloaded cycling TT performance (2.1%; p=0.033), which was seen as an increased power output during the first and last 2 km. However, caffeine failed to significantly improve handcycling performance (1.8%; p=0.153).
  • Participants with a UBE VO2peak greater than the mean value (27.6 ml∙kg∙min-1) improved their handcycling TT performance by 3.2% whereas those below the mean had a 0.3% reduction. Hence, training status may help to explain the inter-individual variability reported in this study.
  • Caffeine resulted in greater blood lactate concentrations post-TT, which is common in the literature, especially in conjunction with improved performance.
  • Caffeine reduced ratings of perceived exertion during constant rate cycling and handcycling but this effect was diminished during the highintensity TT.
  • The lack of performance improvement during the handcycling TT may be linked to a smaller proportion of type I muscle fibres in the arms compared to the legs in non-specifically UBEtrained participants. It has also been suggested that type II muscle fibres are less sensitive to caffeine.

Reference

  • Graham-Paulson, T.S., Perret, C. and GooseyTolfrey, V.L. (2016). Improvements in cycling but not handcycling 10 km time trial performance in habitual caffeine users. Nutrients. 8(7): E393. DOI: 10.3390/nu8070393