Carbohydrates, frequently consumed following exercise for glycogen resynthesis, have been shown to have other systemic effects in resting men. We examined the effects of postexercise sucrose (a disaccharide carbohydrate) ingestion on the renal, cardiovascular, and sympathetic nervous systems. Eight men consumed 1 l of water (W) or 1 l of a 200 g sucrose solution (S) following 1 hour of bicycle exercise at 70% heart rate reserve. Measurements were made during 2 hours of recovery. Heart rate and systolic blood pressure were elevated following S as compared to W (p < 0.009, p < 0.04, respectively). Diastolic blood pressure was lower after S (p < 0.04) and mean blood pressure did not differ between beverages. Plasma and urinary catecholamines decreased similarly after exercise regardless of treatment. After S insulin (p = 0.0019) and glucose (p = 0.0036) were increased but serum aldosterone (p = 0.0083) and potassium (p = 0.0285) responses were lower. No differences were observed for plasma renin activity. Urine volume and kaliuresis were less after S (p = 0.03, p = 0.03). A 24% increase in metabolic rate (p = 0.002) and increased respiratory exchange ratio (p = 0.02) after S were observed. Systemic effects of sucrose ingestion following exercise include cardiovascular, renal, endocrine, and metabolic changes.

Plasma renin activity (PRA), volume (PV), osmolality, and hemodynamic parameters were examined in relation to the anaerobic threshold (AT) during progressive cycle ergometry (PE) and repetitive bouts of unilateral isokinetic knee extension-flexion (LE) at 50% maximum voluntary contractions in eight normotensive males. During PE, the observed rise in PRA paralleled that of lactate with abrupt increases occurring at the AT. Correlation of % delta lactate (La), % delta osmolality, and % delta PV with % delta PRA were r = 0.65, 0.36, and -0.51, respectively (all P less than 0.01). In addition, when mean arterial pressure was plotted as a function of VO2, the rate of rise was greater below the AT than above the AT (11.5 vs. -2.4 mmHg X l-1 X min, P less than 0.001). A time control study (TC) exercising subjects for the same duration but at work rates maintained below the AT resulted in significantly lower values for both PRA and La (7.18 vs. 11.27 mg angiotensin I (ANG I) X ml-1 X min and 3.16 vs. 9.93 mM, P less than 0.05 for TC vs. PE) while producing a similar fall in % delta PV and rise in osmolality. During LE, a high correlation was obtained for % delta PRA and % delta La (r = 0.86, P less than 0.01) but not for % delta PRA with % delta PV or % delta osmolality. The data demonstrate that PRA parallels lactate during exercise and that mean arterial pressure rises more slowly beyond the AT despite a more rapid rise in PRA.

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We speculate that hyperinsulinemia contributed to the rapid decline in K and aldosterone by creating a flux of K to the intracellular space. It appears that CHO ingestion postexercise results in systemic effects that are related to the amount and timing of CHO consumed.