Improved Exercise Tolerance with Caffeine Is Associated with Modulation of both Peripheral and Central Neural Processes in Human Participants.

Journal article


Bowtell, JL, Mohr, M, Fulford, J, Jackman, SR, Ermidis, G, Krustrup, P and Mileva, KN (2018). Improved Exercise Tolerance with Caffeine Is Associated with Modulation of both Peripheral and Central Neural Processes in Human Participants. Frontiers in Nutrition. 5, p. 6.
AuthorsBowtell, JL, Mohr, M, Fulford, J, Jackman, SR, Ermidis, G, Krustrup, P and Mileva, KN
Abstract

Background: Caffeine has been shown to enhance exercise performance and capacity. The mechanisms remain unclear but are suggested to relate to adenosine receptor antagonism, resulting in increased central motor drive, reduced perception of effort, and altered peripheral processes such as enhanced calcium handling and extracellular potassium regulation. Our aims were to investigate how caffeine (i) affects knee extensor PCr kinetics and pH during repeated sets of single-leg knee extensor exercise to task failure and (ii) modulates the interplay between central and peripheral neural processes. We hypothesized that the caffeine-induced extension of exercise capacity during repeated sets of exercise would occur despite greater disturbance of the muscle milieu due to enhanced peripheral and corticospinal excitatory output, central motor drive, and muscle contractility. Methods: Nine healthy active young men performed five sets of intense single-leg knee extensor exercise to task failure on four separate occasions: for two visits (6 mg·kg-1caffeine vs placebo), quadriceps31P-magnetic resonance spectroscopy scans were performed to quantify phosphocreatine kinetics and pH, and for the remaining two visits (6 mg·kg-1caffeine vs placebo), femoral nerve electrical and transcranial magnetic stimulation of the quadriceps cortical motor area were applied pre- and post exercise. Results: The total exercise time was 17.9 ± 6.0% longer in the caffeine (1,225 ± 86 s) than in the placebo trial (1,049 ± 73 s,p = 0.016), and muscle phosphocreatine concentration and pH (p< 0.05) were significantly lower in the latter sets of exercise after caffeine ingestion. Voluntary activation (VA) (peripheral,p = 0.007; but not supraspinal,p = 0.074), motor-evoked potential (MEP) amplitude (p = 0.007), and contractility (contraction time,p = 0.009; and relaxation rate,p = 0.003) were significantly higher after caffeine consumption, but at task failure MEP amplitude and VA were not different from placebo. Caffeine prevented the reduction in M-wave amplitude that occurred at task failure (p = 0.039). Conclusion: Caffeine supplementation improved high-intensity exercise tolerance despite greater-end exercise knee extensor phosphocreatine depletion and H+accumulation. Caffeine-induced increases in central motor drive and corticospinal excitability were attenuated at task failure. This may have been induced by the afferent feedback of the greater disturbance of the muscle milieu, resulting in a stronger inhibitory input to the spinal and supraspinal motor neurons. However, causality needs to be established through further experiments.

Keywordscaffeine; central fatigue; fatigue; neuromuscular function; transcranial magnetic stimulation
Year2018
JournalFrontiers in Nutrition
Journal citation5, p. 6
PublisherLondon South Bank University
ISSN2296-861X
Digital Object Identifier (DOI)doi:10.3389/fnut.2018.00006
Publication dates
Print12 Feb 2018
Publication process dates
Deposited14 Apr 2018
Accepted17 Jan 2018
Accepted author manuscript
License
CC BY 4.0
Permalink -

https://openresearch.lsbu.ac.uk/item/86vz7

  • 0
    total views
  • 1
    total downloads
  • 0
    views this month
  • 1
    downloads this month

Related outputs

Effect of Immobilisation on Neuromuscular Function In Vivo in Humans: A Systematic Review
Campbell, M, Varley-Campbell, J, Fulford, J, Taylor, B, Mileva, K and Bowtell, J (2019). Effect of Immobilisation on Neuromuscular Function In Vivo in Humans: A Systematic Review. Sports Medicine.
Effect of Hypohydration on Peripheral and Corticospinal Excitability and Voluntary Activation
Bowtell, JL, Avenell, G, Hunter, SP and Mileva, KN (2013). Effect of Hypohydration on Peripheral and Corticospinal Excitability and Voluntary Activation. PLoS ONE. 8 (10), p. e77004.
Repeated sprint training in normobaric hypoxia
Cooke, K, Galvin, HM, Sumners, DP, Mileva, KN and Bowtell, JL (2013). Repeated sprint training in normobaric hypoxia. British Journal of Sports Medicine. 47, pp. i74-i79.
Lower body acceleration and muscular responses to rotational and vertical whole-body vibration of different frequencies and amplitudes
Mileva, K, Zaidell, L, James, DC, Bowtell, J, Pollock, RD, Newham, DJ and Sumners, DP (2019). Lower body acceleration and muscular responses to rotational and vertical whole-body vibration of different frequencies and amplitudes. Dose-Response. 17 (1).
Selected B vitamins and their possible link to the aetiology of age-related sarcopenia: relevance of UK dietary recommendations.
Aytekin, N, Mileva, KN and Cunliffe, AD (2018). Selected B vitamins and their possible link to the aetiology of age-related sarcopenia: relevance of UK dietary recommendations. Nutrition Research Reviews.
Wide-pulse electrical stimulation to an intrinsic foot muscle induces acute functional changes in forefoot-rearfoot coupling behaviour during walking.
James, DC, Chesters, T, Sumners, DP, Cook, DP, Green, DA and Mileva, KN (2012). Wide-pulse electrical stimulation to an intrinsic foot muscle induces acute functional changes in forefoot-rearfoot coupling behaviour during walking. International Journal of Sports Medicine. 34 (5), pp. 438-443.
Low-frequency accelerations over-estimate impact-related shock during walking.
James, DC, Mileva, KN and Cook, DP (2014). Low-frequency accelerations over-estimate impact-related shock during walking. Journal of Electromyography and Kinesiology. 24 (2), pp. 264-270.
The biomechanical characteristics of wearing FitFlop™ sandals highlight significant alterations in gait pattern: a comparative study.
James, DC, Farmer, LJ, Sayers, JB, Cook, DP and Mileva, KN (2015). The biomechanical characteristics of wearing FitFlop™ sandals highlight significant alterations in gait pattern: a comparative study. Clinical Biomechanics. 30 (4), pp. 347-354.
47 An acute session of high-frequency, low-intensity, wide-pulse electrical stimulation evokes fatigue adaptations in an intrinsic foot muscle
James, DC, Mileva, KN and Solan, MC (2015). 47 An acute session of high-frequency, low-intensity, wide-pulse electrical stimulation evokes fatigue adaptations in an intrinsic foot muscle. British Journal of Sports Medicine. 49 (Suppl).
Wide-pulse, high-frequency, low-intensity neuromuscular electrical stimulation has potential for targeted strengthening of an intrinsic foot muscle: a feasibility study
James, DC, Solan, MC and Mileva, KN (2018). Wide-pulse, high-frequency, low-intensity neuromuscular electrical stimulation has potential for targeted strengthening of an intrinsic foot muscle: a feasibility study. Journal of Foot and Ankle Research. 11.
Muscle metabolic and neuromuscular determinants of fatigue during cycling in different exercise intensity domains.
Black, MI, Jones, AM, Blackwell, JR, Bailey, SJ, Wylie, LJ, McDonagh, STJ, Thompson, C, Kelly, J, Sumners, P, Mileva, KN, Bowtell, JL and Vanhatalo, A (2017). Muscle metabolic and neuromuscular determinants of fatigue during cycling in different exercise intensity domains. Journal of Applied Physicology (1985). 122 (3), pp. 446-459.