Resting heart rate and blood pressure in elite Kenyan runners

Previous studies have shown that heart rate (HR) and diastolic blood pressure (BP) may be critically associated to running performance in marathon runners of low-to-medium level. In particular, fast performers show accentuated resting bradycardia and enhanced post-competition vasodilation. PURPOSE: To evaluate HR and BP in elite Kenyan runners and to assess the possible relationship, if any, between these variables and the marathon performance time. METHODS: Thirteen male elite Kenyan runners (28±4 yrs; 60.7±5.5 kg; 171±6 cm; last marathon time: 2 h and 9±3 min) and 10 high-level Caucasian runners (32±5 yrs; 67.8±9.7 kg; 175±5 cm; last marathon time: 2 h and 20±11 min) were enrolled. The morning (at least 12 h after the last training session) post-awakening systolic and diastolic BP and HR (V5 lead) were monitored on a beat-to-beat basis in supine position at rest for 10 min. RESULTS: No differences were observed between Kenyan and Caucasian runners in heart rate (47±3 vs. 49±8 bpm, respectively,) and systolic (112±9 vs. 113±5 mmHg, respectively) BP. On the contrary, diastolic BP (72±9 vs.77±4 mmHg, p<0.05 in Kenyan vs. Caucasian subjects) was significantly reduced in Kenyan athletes. Unexpectedly, a significant negative relationship (r=-0,61; p=0.03) was observed between diastolic BP and last marathon performance time, but in Kenyan runners only. Performance time had no correlation with heart rate and systolic BP in both groups. CONCLUSION: The comparable resting bradycardia observed in both groups of athletes suggests a similar effect of strenuous endurance training on the parasympathetic control of heart rhythm. The lower diastolic BP level in Kenyan runners may be due to different sympathetic control of peripheral resistances in lower limb muscles. The negative association of diastolic BP with running performance (marathon time increases of about 1 min for each 5 mmHg of diastolic BP reduction), observed in Kenyan athletes only, needs further interpretation.