Check the acute influence of caffeine on the autonomic modulation and cardiorespiratory parameters after aerobic exercise. Hypothesized that caffeine can promote a slower recovery of the cardiorespiratory parameters and the SNA recovery after aerobic exercise.

The experimental procedure is divided into three phases, all performed on a treadmill, with a minimum interval of 48 hours between them, in order to allow adequate recovery of the participants. Before the start of the first stage of the experimental protocol or control anthropometric measurements will be carried out, body weight by a digital scale (Plenna, TIN 00139 MAXIMA, Brazil)) and then, using a stadiometer (Plenna, TIN 00139 MAXIMA, Brazil)). The protocols are:

I) Maximum stress test protocol: assessment of the maximum oxygen consumption (VO2max) on a treadmill (Inbrasport / Millennium), using the Bruce protocol.

II) Control Protocol (PC): at this stage the volunteer will ingest compressed form of placebo similar to Protocol III and remained at rest after 15 minutes in the supine position, followed by 30 minutes of aerobic exercise on a treadmill, 5 minutes with speed 6.0 km / h followed by 25 minutes with 60% of VO2max and the final 60 minutes lying recovery.

III) Experimental protocol (PE): In this stage, the volunteer had performed activities similar to the PC, but will make the tablet intake consists of 300mg of caffeine, a value that is within the maximum daily amount allowed under the FDA.

Inclusion Criteria:

• healthy men.

Exclusion Criteria:

• cardiovascular, orthopedic, respiratory and neurological disorders reported or other pathological conditions that prevent the subject to perform the protocols;
• smokers, alcoholics, or who use drugs that influence the activity of the heart.