Ian Newhouse

The effects of prelatent and latent iron deficiency on physical work capacity

In order to examine the effects of mild iron deficiency on physical work capacity, 40 prelatent iron-deficient female endurance runners were studied before and after 8 wk of supplementation with either oral iron (320 mg ferrous sulfate) or a matching placebo. Subjects underwent the following physical work capacity tests: the Wingate cycle ergometer test, the anaerobic speed test, the ventilatory threshold, VO2max, and maximal treadmill velocity during the VO2max test. Muscle biopsy samples pre- and post-treatment were obtained from 17 of the subjects, and these were assayed for citrate synthase and cytoplasmic alpha-glycerophosphate dehydrogenase activity. Subjects were randomly assigned to one of the treatment groups, and a double-blind method of administration of the supplements was used. The differences in improvement scores between the two groups on the work capacity and enzyme activity variables were statistically nonsignificant (P greater than 0.05). Serum ferritin values rose from a mean of 12.4 +/- 4.5 to 37.7 +/- 19.7 ng.ml-1 for the experimental group and from 12.2 +/- 4.3 to 17.2 +/- 8.9 ng.ml-1 for the controls (P = 0.0025), whereas hemoglobin levels remained fairly constant for both groups (P = 0.6). Eight weeks of iron supplementation to prelatent/latent iron-deficient, physically active females did not significantly enhance work capacity. Within the limitations of this study, the presence of a serum ferritin below 20 ng.ml-1 does not pose a significant handicap to physical work capacity.

The effects of magnesium supplementation on exercise performance.

PURPOSE To determine the effects of magnesium (Mg2+) supplementation on performance and recovery in physically active women using the sensitive and recently advanced measure of ionic Mg2+ (iMg). METHODS Participants (N = 121) were screened for [iMg] in plasma, with 44 (36.4%) exhibiting [iMg] below the normal range of 0.53-0.67 mmol.L-1 (4). Thirty-two subjects (21 +/- 3 yr) representing a broad range of [iMg] (0.54 +/- 0.04 mmol.L-1) completed the main 14-wk study. At baseline, participants submitted to a resting blood pressure measurement, and they completed both an anaerobic treadmill test and an incremental (aerobic) treadmill test. For the latter, values for workload, oxygen uptake, and heart rate were obtained at both anaerobic threshold and maximal effort. Blood samples for iMg, total serum Mg2+ (TMg), erythrocyte Mg2+ (EMg), Ca2+, K+, Na+, hemoglobin, hematocrit, lactate, and glucose were also collected pretest, and 4, 10, 30 min, and 24 h posttest. Subjects received 212 mg.d-1 Mg oxide or placebo in a double-blind fashion and were retested after 4 wk. After a 6-wk washout period, the testing was repeated with a treatment crossover. RESULTS Ionic Mg2+ increased with Mg2+ treatment versus placebo (P < 0.05); however, performance and recovery indices were not significantly affected. CONCLUSION Four weeks of 212 mg.d-1 Mg oxide supplementation improves resting [iMg] levels but not performance or recovery in physically active women.

The effects of antioxidant vitamin supplementation on resistance exercise induced lipid peroxidation in trained and untrained participants

BackgroundThe theoretical benefits of using antioxidant vitamin supplements to quench oxygen free radicals appear large. High intensity aerobic-type exercise produces oxygen free radicals that can cause damage to lipid membranes (lipid peroxidation) that may lead to many problems such as the inactivation of cell membrane enzymes, the progression of degenerative diseases (cardiovascular disease and cancer) and lessening of the effectiveness of the immune system. The major function of vitamin E is to work as a chain-breaking antioxidant in a fat soluble environment. Little research has examined lipid peroxidation associated with high intensity resistance exercise or possible protective effects of antioxidant supplementation or the effects of training state.ResultsThere were no significant group (trained vs untrained) or treatment (vitamin E vs placebo) effects found between the 4 groups assessed. There was only one significant difference found and that was in the main effect for time (F = 22.41, p < 0.01).ConclusionsThe Resistance Exercise Test caused a significant increase in malondialdehyde in all 4 groups at 6 hours post exercise. There was no evidence that vitamin E supplementation was effective in reducing oxidative damage in comparison to the placebo group. As well, there was no difference between the trained and untrained groups with respect to their impact on lipid peroxidation measures.

The effect of exercise intensity on hematuria in healthy male runners.

Abstract The purpose of this study were: (1) to establish the prevalence of exercise-induced hematuria in a group of otherwise healthy male runners (n = 70), and (2) to investigate the role of exercise intensity in those runners who exhibited exercise-related hematuria (n = 10) by evaluating the effect of running and cycling at high and low intensities. The identified and recruited subjects participated in four different exercise protocols: (1) a 60-min treadmill run (RUN) at 90% of anaerobic threshold (Thae), (2) a 60-min leg cycle ergometer ride (BIKE) at 90% of Thae, (3) a 3×400-m sprint (SPRINT), each followed by 4 min of rest or light walking, and (4) 3×60-Wingate leg cycle ergometry tests, each followed by 4 min of rest or light cycling. The study employed a 3×4 (time by protocol) within-subjects design and dependent variables were measured before exercise, 4 min after, and 1 h after exercise, and included measurements of hematuria, proteinuria, urinary pH, serum haptoglobin concentration, serum creatine phosphokinase activity, plasma lactate concentration, and hemoglobin. The 400-m sprint at maximal effort significantly increased both hematuria and proteinuria (P < 0.01). Post-exercise hematuria for the SPRINT protocol was significantly different than that for the BIKE (P < 0.01) and RUN (P < 0.01) protocols. Due to the significant increase in hematuria and proteinuria following the SPRINT protocol, it was concluded that exercise-related changes in renal function were associated with weight-bearing exercise intensity rather than non-weight-bearing exercise duration.

Sport-related Hematuria: A Review

ObjectiveTo present an overview and models of the potential causes and implications of sport-related hematuria in an athletic population as provided by a literature review. Data SourcesA total of 64 published scientific articles have been utilized to provide a review of sport-related hematuria. Study SelectionReviewed studies were selected on the basis that they provided informative findings about the possible mechanisms of sport-related hematuria attributed to exercise duration and intensity. These studies used both normal adult and athletic populations. Data extractionA review of the literature on the potential mechanisms of sport-related hematuria led to the classification of these mechanisms as either exercise duration related or exercise intensity related. Data synthesisResearch has revealed an increased prevalence of hematuria in athletes. The mechanisms responsible may be traced to different sources or a combination thereof. Many explanations have been directed toward a potential cause; foot-strike hemolysis, renal ischemia, hypoxic damage to the kidney, the release of a hemolyzing factor, bladder and/or kidney trauma, nonsteroidal anti-inflammatory drugs, dehydration, increased circulation rate, myoglobinuria release, and the peroxidation of red blood cells. These mechanisms are presented in two models depicting the influence of either exercise intensity or exercise duration on sport-related hematuria. ConclusionsAthletes, coaches, and sports medicine professionals should be aware of this condition because frequent high-intensity and/or long-duration workouts and competitions may promote the symptoms. Repeated red blood cell loss through the urine may be a contributing factor toward promoting anemic conditions in competitive athletes. Recognition of the potential mechanisms can spare the time and expense of invasive testing.

The effects of magnesium supplementation on exercise performance

ObjectivesMagnesium (Mg) status, although difficult to assess, is suspected to be marginal in many individuals, especially athletes, and this has led to the common use of Mg supplements. The purpose of this article is to critique research that has addressed Mg supplementation in athletes. Data SourcesThe primary database was Medline, which was searched for English articles from 1966 to June 1999 using the words “magnesium” and “supplementation.” Study SelectionOnly experimental studies dealing with human subjects, Mg supplementation, and exercise performance were critiqued (n = 12). Data ExtractionQuality of critiqued articles was based on 1) use of cross-over designs, 2) how and if Mg status was assessed, 3) whether treatment was solely Mg supplementation, 4) duration of supplementation, 5) subject number, and 6) degree of experimental control. Articles were classified into “no effect” and “positive effect,” and also were examined in regard to the type of performance outcome (strength, anaerobic–lactacid, and aerobic). Data SynthesisMg is a cofactor to over 325 enzymatic reactions, and a deficiency of the mineral therefore has many physiological and exercise performance implications. Low dietary intakes, as found in many female athletes, coupled with increased urinary losses with exercise, may eventually lead to an Mg deficiency. Strength of evidence favors those studies finding no effect of Mg supplementation, regardless of whether the performance outcome was strength, anaerobic–lactacid, or aerobic. Analysis was confounded due to: 1) variable exercise modes, intensities, and durations, 2) variable training states and ages of subjects, 3) subject selection favoring males and gender differences has not been probed, 4) Mg dosage has ranged from 1 day to 3 months and from 116 mg/day to 500 mg/day, 5) multivitamins/minerals have been ingested with the Mg, 6) with one exception, 1 Mg status was either not reported or reliant on total Mg (TMg), 7) lack of a cross-over design, 8) only one study 2 made note of controlling exercise prior to exercise testing and blood assay, and 9) typical Mg intake measured was only measured in three of the studies. ConclusionsMost evidence indicates no effect of Mg supplementation on performance (strength, anaerobic–lactacid, and aerobic). When only peak treadmill speed during a VO2 max test is examined, the strength of evidence is equivocal. Trained subjects appear to benefit less than untrained subjects, but this observation requires further study. Little research has focused on physically active females who may be at the highest risk for Mg deficiency. Research has been confounded by numerous factors.

Effects of iron supplementation and discontinuation on serum copper, zinc, calcium, and magnesium levels in women

The purpose of this study was: 1) to establish the prevalence of depleted iron stores, iron deficiency, and low serum levels for copper, zinc, calcium, and magnesium in a healthy female population; and 2) to examine the effects of iron supplementation and discontinuation on the serum levels of the above minerals. One hundred eleven healthy women between the ages of 18 and 40 yr reported for fasted morning blood sampling for iron, copper, zinc, calcium, and magnesium status. Forty-five subjects were either iron-deficient as defined by a hemoglobin level below 120 g.l-1 (four subjects) or iron deplete as defined by a serum ferritin value below 20 micrograms.l-1 (43 subjects). Two subjects fit both criteria. This subgroup continued with the study and were prescribed a normal therapeutic iron dose (320 mg elemental iron per day, taken as two Slow-Fe tablets.d-1 for a period of 12 wk). The subjects then discontinued the iron supplementation for a further 12 wk. The response of the various blood minerals was monitored at 6-wk intervals. Twenty-five subjects completed the full 24-wk treatment. The main conclusions to be made from this study were that: 1) For this sample population of women, iron depletion was quite common (39%), although low hemoglobin values (< 120 g.l-1) were only seen in 3.6%. No subjects fell below the criteria for low serum copper levels (< 13.3 mumol.l-1) nor low serum magnesium levels (< 0.6 mmol.l-1). Seven subjects (6.5%) fell below the criteria for low serum zinc levels (< 11.5 mumol.l-1) while two subjects (1.8%) were below the criteria for low serum calcium levels (< 2.20 mmol.l-1). 2) Therapeutic oral iron supplementation was successful in raising mean serum ferritin values from 15.9 micrograms.l-1 to 36.5 micrograms.l-1 but was not associated with decrements in serum copper or calcium levels. 3) The treatment did not significantly effect serum zinc and magnesium levels during the supplementation period, but a downward trend continued through the discontinuation phase so that at 18 and 24 wk serum zinc and magnesium levels were significantly lower than baseline. 4) Oral contraceptive use was associated with elevated serum copper and ferritin values and lowered serum magnesium levels.

Vitamin E supplementation, exercise and lipid peroxidation in human participants

The theoretical benefits of using antioxidant vitamin supplements to quench oxygen free radicals appear large. The major function of vitamin E is to work as a chain-breaking antioxidant in a fat soluble environment so as to protect polyunsaturated fatty acids within membrane phospholipids and in plasma lipoproteins. The purpose of this critical review was to determine whether vitamin E supplementation decreases exercise-induced lipid peroxidation in humans. If vitamin E alone is ineffective, researchers can turn their efforts to other individual antioxidants or combinations. Using the search words “vitamin E”, “exercise”, “lipid peroxidation” and “antioxidant”, all relevant studies since 1985 were identified through a computer search using Pub Med and Sport Discuss databases. Additional articles were reviewed from the reference list of the retrieved articles. Nine vitamin E studies met the criteria of using human participants in an experimental design. Studies were analyzed to determine the strength of evidence regarding the efficacy of vitamin E supplementation. Strength of evidence was based on: (1) number of participants, (2) intensity of the exercise test, (3) type of research design, (4) other controls, (5) the biomarker of lipid peroxidation, (6) the timing of the biomarker measurement, (7) measurement of vitamin E status and (8) correction for plasma volume change. Overall, the six studies showing no effect of vitamin E supplementation had a much higher total score (67) in comparison to the three studies showing positive effects (38). Although limitations have plagued much of the research, vitamin E supplementation does not appear to decrease exercise-induced lipid peroxidation in humans.

Themes Associated With Exercise Adherence in Persons With Parkinson's Disease: A Qualitative Study

ABSTRACT The purpose of this study was to examine motivators important to exercise adherence in a group of older adults with Parkinsons disease (PD). Four participants with PD completed a 6-week hydrotherapy program, followed by participation in a focus group along with their caregivers (n = 4) to examine motivators that were important to exercise adherence. A semi-structured focus group was transcribed verbatim and analyzed using content analysis to identify common patterns and themes. Multiple themes were found that were important to exercise adherence. Constant reassurance and support from the exercise leader was a primary theme for remaining enrolled in an exercise program. Exercising in a group environment and social interaction with other persons with PD were also the themes. Perceived changes in physical ability increased participants’ confidence and motivation to continue to exercise. The findings suggest that the perceived needs of PD exercise participants can be influenced and addressed by exercise leaders, provide opportunities to improve physical function, and support social interaction. Future exercise programs should be designed to provide a venue where the symptoms of PD are not a deterrent to exercise participation.

Managing Heart Failure in the Long-Term Care Setting: Nurses’ Experiences in Ontario, Canada

BackgroundImplementation of heart failure guidelines in long-term care (LTC) settings is challenging. Understanding the conditions of nursing practice can improve management, reduce suffering, and prevent hospital admission of LTC residents living with heart failure. ObjectiveThe aim of the study was to understand the experiences of LTC nurses managing care for residents with heart failure. MethodsThis was a descriptive qualitative study nested in Phase 2 of a three-phase mixed methods project designed to investigate barriers and solutions to implementing the Canadian Cardiovascular Society heart failure guidelines into LTC homes. Five focus groups totaling 33 nurses working in LTC settings in Ontario, Canada, were audiorecorded, then transcribed verbatim, and entered into NVivo9. A complex adaptive systems framework informed this analysis. Thematic content analysis was conducted by the research team. Triangulation, rigorous discussion, and a search for negative cases were conducted. Data were collected between May and July 2010. ResultsNurses characterized their experiences managing heart failure in relation to many influences on their capacity for decision-making in LTC settings: (a) a reactive versus proactive approach to chronic illness; (b) ability to interpret heart failure signs, symptoms, and acuity; (c) compromised information flow; (d) access to resources; and (e) moral distress. DiscussionHeart failure guideline implementation reflects multiple dynamic influences. Leadership that addresses these factors is required to optimize the conditions of heart failure care and related nursing practice.