Cocoa Flavanols and Exercise Capacity

13 participants (highly-trained cyclist, accustomed to exercise testing on ergometers will be enrolled (VO2max>50 ml/kg, FMD >5%, non-smokers, no medication, no diseases, age 20-36, male).

Baseline Testing:

Participants will perform a baseline testing consisting of an ergometric test with a step-wise increase of workload until exhaustion to determine lactate anaerobic threshold and cardio-pulmonary exercise capacity. Vascular function is monitored by Doppler Ultrasound.

In a second test, participants will perform a time trial (goal: as fast as possible)

Flavanol intervention Participants will twice daily receive either a flavanol-poor cocoa drink (13mg/dl)or a flavanol-rich cocoa drink (596mg/dl) over a period of 7 days. Order is randomized and balanced. Subjects will crossover to the second arm after a washout period of 7 days.

Testing performed on baseline day is repeated after the intake of both drinks

In a subgroup of n=6 participants, we will test whether the blood pressure cuff maneuver used for FMD will itself modify nitrite levels. For this the manuever will be completed 4 times and compared to n=6 untreated controls. in another subgroup 6 participants will receive 4times the maneuver but reperfusion will be limited by means of an ultrasound probe.

Inclusion criteria

• highly trained cyclists (VO2 peak > 50 ml/kg bodyweight)
• refrain from cocoa ingestion during trial
• training continued throughout testing
• > 20 years
• male

Exclusion criteria

• > 36 years
• poor endothelial function
• acute infection
• any chronic heart or pulmonary disease
• arrhythmias
• acute or chronic renal failure
• smokers
• cardio-vascular risk factors : diabetes mellitus, hypertension, hyperlipidemia
• intake of nutrition supplements (l-arginine, creatinine)
• intake of WADA listed doping substances