Biomedical subjects

William A Braun

Publications and source records attributed to William A Braun.

4 recordsLinked to original sources

PubMed2004

DOMS-associated changes in ankle and knee joint dynamics during running.

PURPOSE: The purpose of this study was to determine whether leg mechanics change due to DOMS by examining ankle and knee joint kinematics and stiffness before and after a down hill run. METHODS: Sagittal plane kinematics were recorded with high-speed (120 Hz) video at a speed representing 75% of VO2peak of nine well-trained male runners before (RE1) and 48 h after (RE2) a 30-min downhill run. From the recorded video, 10-12 consecutive strides were digitized, and the following variables were calculated for each stride: ankle and knee range of motion (ROM), ankle and knee peak angular velocity, ankle and knee stiffness, and leg vertical stiffness. A repeated measures ANOVA was calculated for each variable (alpha = 0.05). RESULTS: Both knee and ankle ROM during stance decreased with DOMS, but otherwise there were few changes in ankle mechanics with DOMS. Knee stiffness tended to increase during the early portion of stance (from initial stance to maximum angular velocity of flexion) with DOMS, immediately followed by a decrease (to maximum knee flexion) in stiffness. Changes in knee stiffness caused vertical leg stiffness to increase for the initial portion of stance with DOMS. CONCLUSION: Knee mechanics changed such that the knee stiffness increased at initial stance, resulting in an increase in vertical leg stiffness. This change in knee stiffness possibly serves as a protective mechanism to prevent further damage or pain in the knee extensor musculature.

Adult↗

PubMed2003

The effects of a single bout of downhill running and ensuing delayed onset of muscle soreness on running economy performed 48 h later.

Delayed onset of muscle soreness (DOMS) is a common response to exercise involving significant eccentric loading. Symptoms of DOMS vary widely and may include reduced force generating capacity, significant alterations in biochemical indices of muscle and connective tissue health, alteration of neuromuscular function, and changes in mechanical performance. The purpose of the investigation was to examine the effects of downhill running and ensuing DOMS on running economy and stride mechanics. Nine, well-trained distance runners and triathletes participated in the study. Running economy was measured at three relative intensities [65, 75, and 85% of maximal aerobic capacity ( VO(2peak))] before (RE1) and 48 h after (RE2) a 30-min downhill run (-10%) at 70% VO(2peak). Dependent variables included leg muscle soreness, rate of oxygen consumption ( VO(2)), minute ventilation, respiratory exchange ratio, lactate, heart rate, and stride length. These measurements were entered into a two-factor multivariate analysis of variance (MANOVA). The analysis revealed a significant time effect for all variables and a significant interaction (time x intensity) for lactate. The energy cost of locomotion was elevated at RE2 by an average of 3.2%. This was coupled with a significant reduction in stride length. The change in VO(2) was inversely correlated with the change in stride length ( r= -0.535). Lactate was significantly elevated at RE2 for each run intensity, with a mean increase of 0.61 mmol l(-1). Based on these findings, it is suggested that muscle damage led to changes in stride mechanics and a greater reliance on anaerobic methods of energy production, contributing to the change in running economy during DOMS.

Adaptation, Physiological↗

PubMedDate not supplied

Fluids and hydration in prolonged endurance performance.

Numerous studies have confirmed that performance can be impaired when athletes are dehydrated. Endurance athletes should drink beverages containing carbohydrate and electrolyte during and after training or competition. Carbohydrates (sugars) favor consumption and Na(+) favors retention of water. Drinking during competition is desirable compared with fluid ingestion after or before training or competition only. Athletes seldom replace fluids fully due to sweat loss. Proper hydration during training or competition will enhance performance, avoid ensuing thermal stress, maintain plasma volume, delay fatigue, and prevent injuries associated with dehydration and sweat loss. In contrast, hyperhydration or overdrinking before, during, and after endurance events may cause Na(+) depletion and may lead to hyponatremia. It is imperative that endurance athletes replace sweat loss via fluid intake containing about 4% to 8% of carbohydrate solution and electrolytes during training or competition. It is recommended that athletes drink about 500 mL of fluid solution 1 to 2 h before an event and continue to consume cool or cold drinks in regular intervals to replace fluid loss due to sweat. For intense prolonged exercise lasting longer than 1 h, athletes should consume between 30 and 60 g/h and drink between 600 and 1200 mL/h of a solution containing carbohydrate and Na(+) (0.5 to 0.7 g/L of fluid). Maintaining proper hydration before, during, and after training and competition will help reduce fluid loss, maintain performance, lower submaximal exercise heart rate, maintain plasma volume, and reduce heat stress, heat exhaustion, and possibly heat stroke.

Dietary Carbohydrates↗

PubMedDate not supplied

Influence of carbohydrate delivery on the immune response during exercise and recovery from exercise.

Acute, sustained, moderate- to high-intensity exercise has been shown to induce significant alterations in the distribution and function of leukocytes during recovery. In many instances, these changes have been found to reflect a transient impairment of immune function in vitro during recovery from such exercise. Carbohydrate supplementation during exercise has been associated with an attenuation of cortisol production. Because cortisol has been linked to immunosuppression, a growing body of research has examined the influence of carbohydrate supplementation on immune function in response to exercise. New areas along this line of inquiry involve examination of the cytokine response to exercise and the role that carbohydrate may play in regulating the production of proinflammatory cytokines. Inter-relations among the immune response, production of specific cytokines, and cortisol are also examined. The clinical significance of an attenuated immune response when exercising as a result of the administration of supplemental carbohydrate is yet to be determined.

Cell Division↗