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Biomedical subjects

L E Holt

Publications and source records attributed to L E Holt.

At least 19 recordsLinked to original sources
PubMed2002

Exposure to carbon monoxide and nitrogen dioxide in enclosed ice arenas.

This article summarises the latest information on the adverse cardiorespiratory effects of exposure to carbon monoxide (CO) and nitrogen dioxide (NO(2)) in enclosed ice rinks. Sources of CO and NO(2) emissions are identified, current standards for these agents, as well as methods of controlling the emissions, dispersion, and evacuation of these toxic gases are presented. A detailed literature search involving 72 references in English and French from research conducted in North America and Europe was used. Material was from peer reviewed journals and other appropriate sources. Air pollutants such as carbon monoxide (CO), and nitrogen dioxide (NO(2)) which are present in enclosed skating facilities, may exacerbate a pre-existing pathogenic condition in those people who spend considerable time in these environments. Considering the popularity of ice hockey, short track speed skating, and figure skating, and the hundreds of hours that a sensitive person may spend each year in these environments, it would seem appropriate to seek more definitive answers to this important health problem. From the findings and conclusions of the research reviewed in this paper, 10 recommendations are listed.

Air Pollution, Indoor↗
PubMed2001

The effect of 7 days of creatine supplementation on 24-hour urinary creatine excretion.

Since the discovery that oral ingestion of creatine leads to an increase in intramuscular creatine, its supplementation has become widespread. However, the dosage necessary to maximize retention and create significant increases in intramuscular creatine is poorly understood. In this study, 24-hour urinary creatine and creatinine levels of 20 university men's football players and 20 university men's hockey players involved in a resistance-exercise program and supplementing with creatine were collected and analyzed. In a double-blind, randomized design, 10 football players and 10 hockey players were randomly assigned to either the supplement or placebo group. Subjects provided a 24-hour urine sample twice during the study: once prior to supplementation (baseline) and the second 7 days after daily supplementation and resistance exercise. Creatine dosage was 0.1 g x kg(-1) lean body mass. The quantity of creatine ingested was compared with the amount excreted in the urine of those subjects supplementing with creatine and with placebo. Creatinine levels were compared between the first and second urine collection and between groups. Creatine and creatinine concentrations were determined using high-performance liquid chromatography. In 24-hours, 46% of the ingested creatine was excreted. There was no change in creatine levels for placebo subjects. Creatinine levels remained the same within groups at the first and second collection times (p < 0.05). Our findings indicate that when supplementing with dosages of 0.1 g x kg(-1) lean body mass or between 6 and 8 g at a time, approximately half of the ingested creatine gets excreted. Because there was no change in urinary creatinine, it can be assumed that enhanced degradation of creatine did not occur.

Administration, Oral↗
PubMed2001

Acupuncture in human performance.

To this point in time, acupuncture has been used primarily as an analgesic, a therapeutic intervention that controls pain under pathological conditions. Although some of the mechanisms of acupuncture as it applies to pain relief have been studied, little is known of the positive and/or negative effects of this procedure on the physical performance parameters of healthy people, particularly highly trained athletes. After introducing acupuncture from historical and technique viewpoints, preliminary studies of the effects of acupuncture on strength, aerobic conditioning, flexibility, and sport performance are discussed, as well as concerns regarding the direction of research investigating the potential benefit and/ or adverse effects of this practice. Finally, an argument is put forward for the establishment of guidelines for the use of acupuncture in the sports community.

Acupuncture Therapy↗
PubMed2000

In vivo evaluation of brain iron in Alzheimer disease using magnetic resonance imaging.

BACKGROUND: The basal ganglia contain the highest levels of iron in the brain, and postmortem studies indicate a disruption of iron metabolism in the basal ganglia of patients with Alzheimer disease (AD). Iron can catalyze free radical reactions and may contribute to oxidative damage observed in AD brains. Treatments aimed at reducing oxidative damage have offered novel ways to delay the rate of progression and could possibly defer the onset of AD. Brain iron levels were quantified in vivo using a new magnetic resonance imaging method. METHODS: Thirty-one patients with AD and 68 control subjects participated in this study. A magnetic resonance imaging method was employed that quantifies the iron content of ferritin molecules (ferritin iron) with specificity through the combined use of high and low field-strength magnetic resonance imaging instruments. Three basal ganglia structures (caudate, putamen, and globus pallidus) and one comparison region (frontal lobe white matter) were evaluated. RESULTS: Basal ganglia ferritin iron levels were significantly increased in the caudate (P = .007; effect size, 0.69) and putamen (P = .008; effect size, 0.67) of AD subjects, with a trend toward an increase in the globus pallidus (P = .13). The increased basal ganglia ferritin iron levels were not a generalized phenomenon; white matter ferritin iron levels were unchanged in patients with AD (P = .50). CONCLUSIONS: The data replicate and extend prior results and suggest that basal ganglia ferritin iron levels are increased in AD. Prospective studies are needed to evaluate whether premorbid iron levels are increased in individuals who develop AD.

Age Factors↗
PubMed2000

The effect of continuous low dose creatine supplementation on force, power, and total work.

Dietary supplementation (SUP) has become a significant part of athletic training. Studies indicate that creatine (Cr) can enhance short-duration, high-intensity activities. This study examined the effect of 21 days of low dose Cr SUP ( approximately 7.7 g/day) and resistance training on force output, power output, duration of mean peak power output, and total work performed until fatigue. A double-blind protocol was used, where an individual, who was not part of any other aspect of the study, randomly assigned subjects to creatine and placebo groups. Forty-one male university athletes were randomly assigned to either Cr (n = 20) or placebo (n = 21) SUP. On the first and last day of the study, subjects were required to perform concentric bench press movements until exhaustion on an isokinetic dynamometer. The dynamometer was hard-wired to a personal computer, which provided force, velocity, and duration measures. Force and power output until fatigue, were used to determine total work, force-time, and power-time relationships. ANOVA results revealed that the Cr subjects performed more total work until fatigue, experienced significantly greater improvements in peak force and peak power, and maintained elevated mean peak power for a longer period of time. These results indicate that Cr SUP can significantly improve factors associated with short-duration, high-intensity activity.

Adult↗
PubMed1999

Modifications to the Standard Sit-and-Reach Flexibility Protocol.

OBJECTIVE: To present several modifications of the standard sit-and-reach protocol. BACKGROUND: Many exercises designed to increase strength and aerobic capacity tend to decrease the flexibility of the erector spinae and hamstrings musculature. Less-than-ideal flexibility in these soft tissues may increase the risk of injury during training, competition, or activities of daily living. The most widely used measures of flexibility have been either the stand-and-reach or the sit-and-reach, but both are limited to a single measure. DESCRIPTION: Using the new multitest flexometer, we were able to take 6 flexibility measures beyond the stand-and-reach test: standard active sit-and-reach, standard passive sit-and-reach, modified active sit-and-reach with external rotators slackened, modified passive sit-and-reach with external rotators slackened, modified active sit-and-reach with the hamstrings, gastrocnemii, and external rotators slackened, and modified passive sit-and-reach with the hamstrings, gastrocnemii, and external rotators slackened. CLINICAL ADVANTAGES: This modified sit-and-reach protocol allows the indirect assessment of the influence of the 4 major muscle groups that affect sit-and-reach scores: erector spinae, hip rotators, hamstrings, and gastrocnemii.

Journal Article↗
PubMed1995

P300 topography in Alzheimer's disease.

This study assessed whether P300 scalp topography distinguished subjects with Alzheimer's disease (AD) from controls. Specifically, it was predicted that the AD group would show maximum P300 amplitude over frontal areas and the largest P300 reduction over parietal and left hemisphere areas. These hypotheses were tested using a standard auditory oddball paradigm to compare 26 AD subjects and 26 controls matched on age, sex, handedness, and education. P300 was measured at frontal, central, parietal, and occipital sites over left and right hemispheres and along the midline. Results revealed that the distribution of P300 was different for the two groups such that the controls manifested a maximum over parietal areas, whereas the AD subjects showed a maximum at frontal sites with the largest reductions in P300 over parietal areas. No hemispheric differences in P300 were found. These results are consistent with the hypothesis that P300 represents the activity of multiple neural generators that are differentially disrupted by the disease process.

Adult↗
PubMed1995

Hemodynamics during a machine-aided flexibility protocol.

Heart rates and systolic and diastolic blood pressures of 15 subjects were measured before, during, and after a series of four proprioceptive neuromuscular facilitation (PNF) flexibility exercises. The protocol for the study involved the use of two new machines, one designed to increase flexibility of the erector spinae, the other the hamstrings. Each machine provided constant feedback of isometric force, angular displacements, time of contraction, repetitions, and other exercise variables. Each bout of exercise involved an isometric contraction of the lengthened agonist muscle group (12 sec) followed by a concentric contraction of its antagonist in order to place the body part in a more stretched position. Hemodynamic measurements were determined at both a perceived maximal voluntary isometric contraction (MVIC) and at 50% MVIC. Significant increases in hemodynamic factors were observed when exercise measures were compared to pre- and postexercise (resting) values. Higher values, though not significantly so, were found at MVIC than at 50% MVIC on both machines. All values were well within the guidelines of the American College of Sports Medicine.

Adolescent↗
PubMed1995

The etiology of paddler's shoulder.

Training methods used in competitive flatwater paddling often lead to a common pattern of soft tissue injuries that affect the upper limb. Of particular frequency is paddler's shoulder, a condition that can become chronic and may result in permanent damage. The authors suggest that the cumulative effect of poorly structured resistance training initiates the deteriorative process and together with the repetitiveness of on-water training results in the pathologies referred to as paddler's shoulder.

Athletic Injuries↗
PubMed1994

In vivo evaluation of brain iron in Alzheimer's disease and normal subjects using MRI.

Magnetic resonance imaging (MRI) can measure transverse relaxation rate (R2) of tissues. Although R2 is increased by tissue iron levels, R2 is not a specific measure of iron. A new method, based on the fact that ferritin (the primary tissue iron storage protein) affects R2 in a field-dependent manner, can quantify tissue iron with specificity by measuring the Field Dependent R2 Increase (FDRI). Using the FDRI method, we compared brain iron stores in frontal white matter, caudate nucleus, putamen, and globus pallidus of five male patients with Alzheimer disease (AD) and eight age and gender-matched normal controls. FDRI values were significantly higher among AD patients in the caudate and globus pallidus. The data suggest that AD may involve disturbances in brain iron metabolism and that the involvement of iron in the pathophysiology of age-related neurodegenerative disorders can be investigated in vivo using MRI.

Aged↗
PubMed1980

A comparison of selected stop, reverse and start (SRS) techniques in ice hockey.

The purpose of this study was to compare three stop, reverse, and start (SRS) techniques used in the game of ice hockey. Six S's from four levels of competition were instructed in the execution of three skills, then timed over a specified course performing each method. Additionally, selected S's within each group were filmed from frontal and lateral perspectives while performing the tests. A biomechanical analysis of all films was conducted. Both statistical and biomechanical analyses showed a superiority of the "feet parallel, thrust and glide" technique over both techniques employing the "cross over." Conclusion was that the former method should be included in the instructional and competitive programs in Ice Hockey.

Biomechanical Phenomena↗