Cardiorespiratory responses during exercise in competitive in-line skaters.

This study describes the cardiorespiratory responses of 12 male (age = 30 +/- 6 yr) competitive in-line skaters during peak and submaximal skating. We hypothesized that velocities of 22.5 and 27.4 km.h-1 would elicit heart rate (HR) and oxygen consumption (VO2) responses consistent with the American College of Sports Medicine's guidelines for developing cardiorespiratory fitness. Using a 644-m indoor cement course, subjects completed 10 trials comprised of various velocities, stroke frequencies, and body positions. At 22.5 km.h-1, HR and VO2 were 74 and 51% of peak, respectively. At 27.4 km.hr-1, HR and VO2 were 85 and 72% of peak, respectively. When compared to the College's guidelines, regression analysis revealed a leftward shift in the VO2-HR relationship, evidenced by a disproportionately higher HR at a VO2 approximating 60 vs 80% of peak. At 22.5 km.h-1 our skaters self-selected a stroke frequency which resulted in less of an increase in both HR and VO2, when compared to the imposed stroke frequencies of 50 min-1 and 70 min-1. Also, skating at 27.4 km.h-1 in the bent vs upright position resulted in less of an increase in HR and VO2. Competitive in-line skaters are capable of safely skating at velocities sufficient to stimulate an increase in cardiorespiratory fitness. These athletes select a stroke frequency and utilize a body position which results in favorable HR and VO2 responses.

Comparison of the effects of guanadrel sulfate and propranolol on blood pressure, functional capacity, serum lipoproteins and glucose in systemic hypertension.

In a controlled, double-blind, crossover study, the effects of guanadrel sulfate and propranolol on blood pressure (BP) and selected cardiopulmonary and metabolic variables were compared in 15 physically active and moderately hypertensive subjects. Guanadrel sulfate reduced systolic and diastolic BP at rest by -16 and -15 mm Hg, and at maximal exercise by -33 and -13 mm Hg, respectively (p less than 0.005), without affecting submaximal oxygen consumption (VO2), maximal VO2, ventilatory threshold, forced vital capacity, forced expiratory volume in 1 second, or fatigue, as assessed by perceived exertion. In contrast, propranolol significantly decreased diastolic BP at rest (-16 mm Hg) and systolic BP at maximal exercise (-44 mm Hg); however, it significantly decreased submaximal VO2 (-3.9 ml.kg-1.min-1), maximal VO2 (-3.9 ml.kg-1.min-1), ventilatory threshold (-0.3 liters.min-1), minute ventilation at submaximal exercise (-7.3 liters.min-1), forced expiratory volume in 1 second (-0.27 liters), and concomitantly increased the rating of perceived exertion at maximal exercise (1.9 U). Guanadrel sulfate was also associated with significant decreases in mean fasting plasma glucose and total serum cholesterol, whereas propranolol resulted in an increase in serum triglycerides (p less than 0.05). In contrast to propranolol, guanadrel sulfate appears to decrease BP without evoking negative metabolic consequences or impairing exercise tolerance.