Biomedical subjects

E R Kubitz

Publications and source records attributed to E R Kubitz.

3 recordsLinked to original sources

PubMed1995

Run training vs cross training: influence of increased training on running economy, foot impact shock and run performance.

The purpose of the study was to compare changes in running economy, foot impact shock, run performance, and resting heart rate and blood pressure elicited by increases in training volume via run training (RT) and cross training (CT). After 30 d of normal training (NT), male runners (N = 11) completed two 10 d periods of increased training each preceded by 14 d of reduced training (80% NT). Subjects ran 10 consecutive days in the afternoon (100% of NT) and performed 8 additional workouts in the morning (100% of NT). The morning sessions were performed on a cycle ergometer (CT) or a treadmill (RT). Running economy, foot impact shock and lactate were assessed during submaximal running (3.9 +/- 0.06 m.sec-1) at D0 and D11. Following the submaximal run, subjects completed a simulated 5 km race on a treadmill. VO2 during the running economy test was significantly higher at D11 of CT (52.5 +/- 1.5) compared to RT (51.1 +/- 1.4 ml.kg-1.min-1). RER, carbohydrate oxidation, and lactate were significantly lower; whereas, foot impact shock was significantly higher following both training modes. No significant changes in run performance, resting heart rate and blood pressure occurred during the study. In summary, 10 d of increased training resulted in a reduced running economy for CT, and a lower carbohydrate oxidation and an increase in foot impact shock for both training modes.

Adult↗

PubMed1995

A carbohydrate loading regimen improves high intensity, short duration exercise performance.

This investigation examined the effect of a carbohydrate loading regimen on high intensity, short duration run performance. Using a random crossover design, 8 trained runners completed a 15-min submaximal run and a performance run to exhaustion after two dietary treatments. The mixed diet (MD) contained 4.0 +/- 0.5 g.kg-1.d-1 of carbohydrate (CHO) for 6 days. The experimental diet (HCD) contained 4.5 +/- 0.5 g CHO.kg-1.d-1 for 3 days followed by 8.2 +/- 0.4 g CHO kg-1.d-1 for 3 days. Training consisted of daily runs of 90, 40, 40, 20, and 20 min at approximately 75% of VO2max. Day 6 was a rest day, and testing was completed on Day 7. Preexercise lactate, body weight, submaximal VO2, and heart rate did not differ significantly between treatments. Carbohydrate oxidation during submaximal running was higher (p < 0.05) after HCD than after MD. Time to exhaustion in the performance run was longer after HCD compared to MD. Results indicate that a carbohydrate loading regimen increases CHO oxidation during submaximal exercise and improves high intensity, short duration run performance.

Adult↗

PubMed1992

Opioid receptor modulation of postexercise hypotension.

Previous studies of both hypertensive and normotensive individuals have indicated a prolonged reduction in blood pressure for several hours after aerobic exercise. In related studies of spontaneously hypertensive rats, this postexercise hypotension has been prevented with naloxone. The purpose of the present investigation was to examined whether the postexercise hypotension may be reversed by antagonism of opioid sensitive receptors with naloxone in normotensive humans. Eight males 22-34 yr of age, participated in two 60-min cycling trials at 60% of VO2 peak, followed by 29 min of recovery. Beginning at 7-min recovery, naloxone or saline (control) was administered intravenously through an indwelling catheter. Blood pressure and heart rate were monitored every 15 min during exercise and every 2 min during recovery. Heart rate was significantly elevated (P < 0.05) over basal levels for the first 11 min of recovery, but from 13 to 29 min was not different from that measured at rest. In both trials, after 11 min of recovery, systolic and mean arterial blood pressures were significantly (P < 0.05) lower than pre-exercise levels (9 +/- 1 mm Hg and 4 +/- 1 mm Hg, respectively). Injection of naloxone (0.1 mg.kg-1) reversed the hypotensive response. However, the reversal was transient, lasting from minutes 15 to 27. Since naloxone reverses postexercise hypotension, opioid sensitive receptors appear to be involved in the reduction in systolic blood pressure following a single bout of submaximal exercise in normotensive humans.

Adult↗