Clinical trial NCT01167478: Neurophysiological Reserve With Caffeine Manipulation
Official title: Neurophysiological Reserve: Peripheral and Central Effects of Caffeine Manipulation
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Caffeine
Placebo
Keywords: Exercise
Caffeine
Reserve
Lead sponsor: University of Sao Paulo
Sponsor class: OTHER
Collaborators: name: Fundação de Amparo à Pesquisa do Estado de São Paulo
First posted: 2010-07-22
Enrollment: 20
Sex: MALE
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: 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

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 criteria: Inclusion Criteria:

* trained cyclists
* trained in long distance races

Exclusion Criteria:

* Maximum oxygen uptake lower than 55 ml/kg/min

Primary outcomes:
measure: Neurophysiological reserve evidenced by caffeine
timeFrame: Immediately after the administration (around 10 minutes)
measure: Neurophysiological reserve evidenced by caffeine
timeFrame: Immediately after the administration (around 10 minutes)
Secondary outcomes:
measure: Neurophysiological reserve evidenced by placebo
timeFrame: Immediately after the administration (around 10 minutes)
Other outcomes:
Locations:
city: São Paulo
country: Brazil
facility: University of São Paulo
Study officials:
affiliation: University of Sao Paulo
name: Carlos Ugrinowitsch, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Lambert EV, St Clair Gibson A, Noakes TD. Complex systems model of fatigue: integrative homoeostatic control of peripheral physiological systems during exercise in humans. Br J Sports Med. 2005 Jan;39(1):52-62. doi: 10.1136/bjsm.2003.011247.