Neurophysiological Reserve With Caffeine Manipulation

The recruitment status of this study is unknown because the information has not been verified recently.
Verified July 2010 by University of Sao Paulo.
Recruitment status was  Not yet recruiting
Sponsor:
Information provided by:
University of Sao Paulo
ClinicalTrials.gov Identifier:
NCT01167478
First received: July 21, 2010
Last updated: July 22, 2010
Last verified: July 2010
  Purpose

The objective of this study is to verify if there is a neurophysiologic reserve when caffeine and placebo perceived as caffeine are manipulated in closed- and opened-loop exercises. Parameters of excitability level of skeletal muscle and Central Nervous System (CNS), and peripheral metabolism will be measured


Condition Intervention
Cyclists
Trained
Dietary Supplement: Caffeine

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: Double Blind (Subject, Investigator)
Primary Purpose: Treatment
Official Title: Neurophysiological Reserve: Peripheral and Central Effects of Caffeine Manipulation

Resource links provided by NLM:


Further study details as provided by University of Sao Paulo:

Primary Outcome Measures:
  • Neurophysiological reserve evidenced by caffeine [ Time Frame: Immediately after the administration (around 10 minutes) ] [ Designated as safety issue: No ]
    The time to cover a 4-km trial (closed-loop) or the time to exhaustion in an incremental intensity test (opened-loop) can show if the caffeine manipulation affects the performance. In addition, measures of CNS excitability such as EMG during the closed-loop exercise or at the exhaustion point in the opened-loop exercise, and measures such as the amplitude of H reflex, the rate of increase in H reflex/M wave relationship, can indicate if some central or peripheral alteration occurred during the exercises.

  • Neurophysiological reserve evidenced by caffeine [ Time Frame: Immediately after the administration (around 10 minutes) ] [ Designated as safety issue: No ]
    The time to cover a 4-km trial (closed-loop) or the time to exhaustion in an incremental intensity test (opened-loop) can show if the placebo manipulation affects the performance. In addition, measures of CNS excitability such as EMG during the closed-loop exercise or at the exhaustion point in the opened-loop exercise, and measures such as the amplitude of H reflex, the rate of increase in H reflex/M wave relationship, can indicate if some central or peripheral alteration ocurred during the exercises.


Secondary Outcome Measures:
  • Neurophysiological reserve evidenced by placebo [ Time Frame: Immediately after the administration (around 10 minutes) ] [ Designated as safety issue: No ]
    The placebo should also promote decrease in time of trial or increase in mean power output during a closed-loop exercise, elevation in time to exhaustion and maximal power output during an opened-loop exercise, and increase in maximal voluntary isometric contraction (MVIC) and time to contraction in a target force. Also, there should be a higher CNS excitability such as: 1) higher EMG during closed-loop exercise and higher EMG at the exhaustion point in an opened-loop exercise; 2) increased amplitude of H reflex; 3) elevation on the rate of increase in H reflex/M wave relationship.


Estimated Enrollment: 20
Study Start Date: October 2010
Estimated Study Completion Date: September 2011
Estimated Primary Completion Date: March 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Caffeine Dietary Supplement: Caffeine
After ingestion of 6 mg.kg-1 of body mass of caffeine, subjects will perform the one exercise trial.
Dietary Supplement: Caffeine
6 mg/kg of body mass of caffeine will be ingested by subjects before exercise.

Detailed Description:

A neurophysiological reserve related to central mechanisms is supposed to be present, which should be observed when an increased central drive occurs. In theory, according to the central regulation model of effort, an increased performance could be due to the elevation on Central Nervous System excitability and activity, since exercise is not peripherally limited. Conversely, the absence of muscle performance improvement to the increased central drive promoted by caffeine would be an evidence for a peripherally localized neurophysiological limit and would indicate the absence of reserve. Therefore, if present, this reserve could be verified by using peripheral and central measures derived from electric-stimulation, evoked twitch and interpolated twitch techniques, associated to measures of EMG and peripheral metabolism, when caffeine is manipulated during closed- and opened-loop exercise.

In addition, there should also be possible to access the reserve without stimulant substance manipulation (placebo effect). By teleological argument derived from the central regulation model of effort, a neurophysiological reserve would be a natural mechanism to protect the cellular integrity. Therefore, it would be reasonable to hypothesize that, if present, a reserve would be observed by an increase in performance promoted by an elevation in central drive when placebo is perceived as caffeine. Unfortunately, however, no study utilized this experimental approach, including measures of central and peripheral activity during closed- and opened-loop exercise, to consistently respond the reserve question.

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • trained cyclists
  • trained in long distance races

Exclusion Criteria:

  • Maximum oxygen uptake lower than 55 ml/kg/min
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01167478

Contacts
Contact: Carlos Ugrinowitsch, PhD 55-11-30913179 Ugrinowitsch@gmail.com
Contact: Flavio O Pires, PhD 55-11-30913179 piresfo@usp.br

Locations
Brazil
University of São Paulo Not yet recruiting
São Paulo, Brazil, 05508-030
Contact: Carlos Ugrinowitsch, PhD    55-11-30912143    Ugrinowitsch@gmail.com   
Contact: Flavio O Pires, PhD    55-11-30913179    piresfo@usp.br   
Principal Investigator: Carlos Ugrinowitsch, PhD         
Sponsors and Collaborators
University of Sao Paulo
Investigators
Principal Investigator: Carlos Ugrinowitsch, PhD University of São Paulo
  More Information

Publications:
Responsible Party: University of São Paulo, School of Physical Education and Sports
ClinicalTrials.gov Identifier: NCT01167478     History of Changes
Other Study ID Numbers: EEFE026, 2010/01317-0
Study First Received: July 21, 2010
Last Updated: July 22, 2010
Health Authority: Brazil: Ethics Committee

Keywords provided by University of Sao Paulo:
Exercise
caffeine
reserve

Additional relevant MeSH terms:
Caffeine
Central Nervous System Stimulants
Physiological Effects of Drugs
Pharmacologic Actions
Central Nervous System Agents
Therapeutic Uses
Phosphodiesterase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Purinergic P1 Receptor Antagonists
Purinergic Antagonists
Purinergic Agents
Neurotransmitter Agents

ClinicalTrials.gov processed this record on July 26, 2014