Exercise Physiology Research Research Articles

Using a novel data resource to explore heart rate during mountain and road running.

Online, accessible performance and heart rate data from running competitions are posted publicly or semi‐publicly to social media. We tested the efficacy of one such data resource‐ Strava‐ as a tool in exercise physiology investigations by exploring heart rate differences in mountain racing and road racing running events. Heart rate and GPS pace data were gathered from Strava activities posted by 111 males aged 21–49, from two mountain races (Mt. Washington Road Race and Pike's Peak Ascent) and two road race distances (half marathon and marathon). Variables of interest included race finish time, average heart rate, time to complete the first half (by distance) of the race, time to complete the second half, average heart rate for both the first and second half, estimated maximal heart rate, and competitiveness (finish time as percentage of winning time). Mountain runners on average showed no change in heart rate in the second versus first half of the event, while road racers at the half marathon and marathon distances showed increased second‐half heart rate. Mountain runners slowed considerably more in the second half than road runners. Heart rate increases in road races were likely reflective of cardiac drift. Altitude and other demands specific to mountain racing may explain why this was not observed in mountain races. Strava presents enormous untapped opportunity for exercise physiology research, enabling initial inquiry into physiological questions that may then be followed by targeted laboratory studies.

"Weighing" the effects of exercise and intrinsic aerobic capacity: are there beneficial effects independent of changes in weight?

It has been known for centuries that regularly performed exercise has beneficial effects on metabolic health. Owing to its central role in locomotion and the fact that it accounts for a large majority of whole-body glucose disposal and fatty acid oxidation, the effects of exercise on skeletal muscle has been a central focus in exercise physiology research. With this being said it is becoming increasingly well recognized that both adipose tissue and liver metabolism are robustly modified by exercise, especially in conditions of obesity and insulin resistance. One of the difficult questions to address is if the effects of exercise are direct or occur secondary to exercise-induced weight loss. The purpose of this review is to highlight recent work that has attempted to tease out the protective effects of exercise, or intrinsic aerobic capacity, against metabolic and inflammatory challenges as it relates to the treatment and prevention of obesity and insulin resistance. Recent studies reporting improvements in liver and adipose tissue insulin action following a single bout of exercise will also be discussed. The research highlighted in this review sheds new insight into protective, anti-inflammatory effects of exercise that occur largely independent of changes in adiposity and body weight.

Definition of the thermographic regions of interest in cycling by using a factor analysis

Research in exercise physiology using infrared thermography has increased in the last years. However, the definition of the Regions of Interest (ROIs) varies strongly between studies. Therefore, the aim of this study was to use a factor analysis approach to define highly correlated groups of thermographic ROIs during a cycling test. Factor analyses were performed based on the moment of measurement and on the variation of skin temperatures as a result of the cycling exercise. 19 male participants cycled during 45min at 50% of their individual peak power output with a cadence of 90rpm. Infrared thermography was used to measure skin temperatures in sixteen ROIs of the trunk and lower limbs at three moments: before, immediately after and 10min after the cycling test. Factor analyses were used to identify groups of ROIs based on the skin absolute temperatures at each moment of measurement as well as on skin temperature variations between moments. All the factor analyses performed for each moment and skin temperature variation explained more than the 80% of the variance. Different groups of ROIs were obtained when the analysis was based on the moment of measurement or on the effect of exercise on the skin temperature. Furthermore, some ROIs were grouped in the same way in both analyses (e.g. the ROIs of the trunk), whereas other regions (legs and their joints) were grouped differently in each analysis. Differences between groups of ROIs are related to their tissue composition, muscular activity and capacity of sweating. In conclusion, the resultant groups of ROIs were coherent and could help researchers to define the ROIs in future thermal studies.

Recommendations for Recruiting and Retaining Adolescent Girls in Chronic Exercise (Training) Research Studies

Extensive challenges are often encountered when recruiting participants to chronic exercise (training) studies. High participant burden during chronic exercise training programmes can result in low uptake to and/or poor compliance with the study. The aim of this qualitative study was to identify factors affecting adolescent girls’ recruitment and adherence to chronic exercise training research studies. Twenty-six adolescent girls (aged 12 to 15 years) participated in one of five focus groups discussing recruitment and retention to exercise physiology research involving a chronic exercise training programme. A thematic analysis was used to analyse the data and eight final themes were inductively identified. Seven evidence-based practical recommendations are suggested to improve the recruitment and retention of participants for prospective, chronic exercise training studies. Successful recruitment requires: (i) the defining of exercise-related terms; (ii) appropriate choice of recruitment material; and (iii) an understanding of participant motivations. Retention strategies include: (iv) regular monitoring of participant motives; and (v) small groups which foster peer and researcher support. Finally, (vi) friendship and ability groups were favoured in addition to (vii) a variety of activities to promote adherence to an exercise training programme.

The rat adequately reflects human responses to exercise in blood biochemical profile: a comparative study.

Animal models are widely used in biology and the findings of animal research are traditionally projected to humans. However, recent publications have raised concerns with regard to what extent animals and humans respond similar to physiological stimuli. Original data on direct in vivo comparison between animals and humans are scarce and no study has addressed this issue after exercise. We aimed to compare side by side in the same experimental setup rat and human responses to an acute exercise bout of matched intensity and duration. Rats and humans ran on a treadmill at 86% of maximal velocity until exhaustion. Pre and post exercise we measured 30 blood chemistry parameters, which evaluate iron status, lipid profile, glucose regulation, protein metabolism, liver, and renal function. ANOVA indicated that almost all biochemical parameters followed a similar alteration pattern post exercise in rats and humans. In fact, there were only 2/30 significant species × exercise interactions (in testosterone and globulins), indicating different responses to exercise between rats and humans. On the contrary, the main effect of exercise was significant in 15/30 parameters and marginally nonsignificant in other two parameters (copper, P = 0.060 and apolipoprotein B, P = 0.058). Our major finding is that the rat adequately mimics human responses to exercise in those basic blood biochemical parameters reported here. The physiological resemblance of rat and human blood responses after exercise to exhaustion on a treadmill indicates that the use of blood chemistry in rats for exercise physiology research is justified.

How can bioinformatics and toxicogenomics assist the next generation of research on physical exercise and athletic performance.

The past 2-3 decades have seen an explosion in analytical areas related to "omic" technologies. These advancements have reached a point where their application can be and are being used as a part of exercise physiology and sport performance research. Such advancements have drastically enabled researchers to analyze extremely large groups of data that can provide amounts of information never before made available. Although these "omic" technologies offer exciting possibilities, the analytical costs and time required to complete the statistical approaches are substantial. The areas of exercise physiology and sport performance continue to witness an exponential growth of published studies using any combination of these techniques. Because more investigators within these traditionally applied science disciplines use these approaches, the need for efficient, thoughtful, and accurate extraction of information from electronic databases is paramount. As before, these disciplines can learn much from other disciplines who have already developed software and technologies to rapidly enhance the quality of results received when searching for key information. In addition, further development and interest in areas such as toxicogenomics could aid in the development and identification of more accurate testing programs for illicit drugs, performance enhancing drugs abused in sport, and better therapeutic outcomes from prescribed drug use. This review is intended to offer a discussion related to how bioinformatics approaches may assist the new generation of "omic" research in areas related to exercise physiology and toxicogenomics. Consequently, more focus will be placed on popular tools that are already available for analyzing such complex data and highlighting additional strategies and considerations that can further aid in developing new tools and data management approaches to assist future research in this field. It is our contention that introducing more scientists to how this type of work can complement existing experimental approaches within exercise physiology and sport performance will foster additional discussion and stimulate new research in these areas.

The Thermodynamics of Exercise Science

This article describes the “human body engine” via a thermodynamics-based model that considers the work associated with gas pressure, volume and temperature changes for the glucose-based equation of respiration. The efficacy of the model is supported by prior studies that: accurately predict the slow component of oxygen uptake kinetics; quantitatively explain observed race splitting strategies within endurance events; and accurately predict maximum velocities in endurance swimming. These prior studies are summarized by the review component of the present article which additionally presents new temperature-dependent efficiency implications especially relevant for heat-affected athletes. The new model implications support reported experimental observations and also potentially provide quantified clarity to an area of exercise physiology research known to be challenged by opposing experimental findings, thus providing further support for model efficacy. A 0.32% efficiency decline per 1 oC increase in core body temperature is predicted. The model is also applied to the “ice slurry ingestion” regime which reportedly offers significant performance advantages (greater than that predicted by the model based on core temperature change alone) for endurance athletes competing in the heat, and the model reconciles with such advantages when ice slurry effect on arterial exchange temperatures and partial pressures are incorporated.

Validity and reliability of an alternative method for measuring power output during six-second all-out cycling.

In a laboratory setting where both a mechanically-braked cycling ergometer and a motion analysis (MA) system are available, flywheel angular displacement can be estimated by using MA. The purpose of this investigation was to assess the validity and reliability of a MA method for measuring maximal power output (Pmax) in comparison with a force transducer (FT) method. Eight males and eight females undertook three identical sessions, separated by 4 to 6 days; the first being a familiarization session. Individuals performed three 6-second sprints against 50% of the maximal resistance to complete two pedal revolutions with a 3-minute rest between trials. Power was determined independently using both MA and FT analyses. Validity: MA recorded significantly higher Pmax than FT (P < .05). Bland-Altman plots showed that there was a systematic bias in the difference between the measures of the two systems. This difference increased as power increased. Repeatability: Intraclass correlation coefficients were on average 0.90 ± 0.05 in males and 0.85 ± 0.08 in females. Measuring Pmax by MA, therefore, is as appropriate for use in exercise physiology research as Pmax measured by FT, provided that a bias between these measurements methods is allowed for.

In Memoriam

In Memoriam

The defence of legitimate exercise physiology research from real and perceived bias: a rebuttal

Dear Editor, A recent publication entitled ‘Is this the new smoking? An expert panel review of the York University OHV health benefits study’ published in Health Promotion International (Bissix et al., 2012) claimed to systematically appraise the scientific methodology upon which a series of health-related investigations into off-highway vehicle (OHV) participation were based. The authors concluded that the science regarding the health impacts of OHV riding is ‘indefensible’ based on conceptual, methodological and interpretive limitations. Beginning with the title and prevalent throughout the article, there is a pervasive suggestion that our study had a research bias. To suggest that we have such a deficiency of integrity is the greatest possible insult to a serious scholar, and it is audacious of Bissix et al. to draw comparisons between the OHV health and chronic disease risk investigation and the travesties in some past smoking research. This is an accusation to which we (the authors of this original research) take great offense in no uncertain terms. Furthermore, we suggest that the article by Bissix et al. claiming to scientifically re-assess our work is an embarrassment to serious researchers, full of poor or irrelevant arguments, misrepresentations of fact, references taken out of context and ludicrous attribution of media reports to our research team. To be clear, we fully support the scientific process of collecting data with a transparent sharing of the methodology and results, allowing work to be re-tested, confirmed or refuted. It is through this scientific method that knowledge is gained and progress is made. However, Bissix et al. have little to contribute to this process owing to their lack of expertise in this area, which is painfully apparent from the uninformed arguments in their article and their absence of published research in our field. As such, this ‘scientific paper’ they have submitted is nothing more than a biased commentary. The egregious errors and omissions in their ‘reinterpretation of our data’ can only be attributed to either (i) a purposeful attempt to mislead or (2) outright ignorance of basic principles of exercise physiology. Extending the authors the benefit of doubt concerning their professional integrity, we will assume that the errors in their article stem primarily from the latter. In this paper, we critically examine and respond to the objections that Bissix et al. have raised in regard to our work. First, to infer that our research was in any way biased by our funding is patently incorrect and an unfounded defamatory accusation. We have formally acknowledged all funding arrangements in every presentation of our data, and made it very clear that our funding partners had no involvement at any stage of the research or manuscript preparation. Our funder’s arms-length relationship to our research was no different from that which exists between any funding agency (be it cancer, heart disease etc.) Health Promotion International, Vol. 28 No. 1 doi:10.1093/heapro/das069 # The Author (2013). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

London 2012: The biomedical basis of elite performance

London 2012: The biomedical basis of elite performance

Proteomics applied to exercise physiology: A cutting‐edge technology

Exercise research has always drawn the attention of the scientific community because it can be widely applied to sport training, health improvement, and disease prevention. For many years numerous tools have been used to investigate the several physiological adaptations induced by exercise stimuli. Nowadays a closer look at the molecular mechanisms underlying metabolic pathways and muscular and cardiovascular adaptation to exercise are among the new trends in exercise physiology research. Considering this, to further understand these adaptations as well as pathology attenuation by exercise, several studies have been conducted using molecular investigations, and this trend looks set to continue. Through enormous biotechnological advances, proteomic tools have facilitated protein analysis within complex biological samples such as plasma and tissue, commonly used in exercise research. Until now, classic proteomic tools such as one- and two-dimensional polyacrylamide gel electrophoresis have been used as standard approaches to investigate proteome modulation by exercise. Furthermore, other recently developed in gel tools such as differential gel electrophoresis (DIGE) and gel-free techniques such as the protein labeling methods (ICAT, SILAC, and iTRAQ) have empowered proteomic quantitative analysis, which may successfully benefit exercise proteomic research. However, despite the three decades of 2-DE development, neither classic nor novel proteomic tools have been convincingly explored by exercise researchers. To this end, this review gives an overview of the directions in which exercise-proteome research is moving and examines the main tools that can be used as a novel strategy in exercise physiology investigation.

A real-time device for converting Doppler ultrasound audio signals into fluid flow velocity

A Doppler signal converter has been developed to facilitate cardiovascular and exercise physiology research. This device directly converts audio signals from a clinical Doppler ultrasound imaging system into a real-time analog signal that accurately represents blood flow velocity and is easily recorded by any standard data acquisition system. This real-time flow velocity signal, when simultaneously recorded with other physiological signals of interest, permits the observation of transient flow response to experimental interventions in a manner not possible when using standard Doppler imaging devices. This converted flow velocity signal also permits a more robust and less subjective analysis of data in a fraction of the time required by previous analytic methods. This signal converter provides this capability inexpensively and requires no modification of either the imaging or data acquisition system.

Investigative learning in exercise physiology research: a liberal arts model

The preparation of students to enter research, clinical, fitness, or management fields is a critical component of our efforts to promote a healthy lifestyle and curb the prevalence of obesity, diabetes, and cardiovascular disease. We report on the impact of investigative learning on exercise science education in a small, liberal arts college. An NSF award facilitated the acquisition of equipment for assessment of physical fitness and performance. Laboratories were redesigned with emphasis on student‐centered investigative activities. Impact was assessed via student surveys and the number and quality of independent research projects. Surveys revealed that 86% of the students found that the equipment improved their laboratory experience and 65% noted that the availability of equipment influenced their choice of research project; 92% indicated that the laboratories enhanced their understanding of the physiological processes during exercise. All students indicated that the experiences enhanced their confidence in designing and conducting experiments. During the last 2 years 8 student research projects were carried out. The laboratory has become a favorite among the 600 middle and high school students who have visited our facilities. Current science education strategies should be applied in Exercise Science education.Supported by a grant from the NSF‐DUE‐CCLI (0511219).

Challenges in Exercise Physiology Research and Education

Similar to other subdisciplines in kinesiology, exercise physiology (EP) as a field is facing challenges in both research (creation and dissemination of new knowledge) and education (classroom instruction and student mentoring). In the current communication, we will learn from the history, analyze the current status of the field, and provide some perspectives based primarily on our knowledge and experience working as faculty members at the University of Wisconsin–Madison.

In memoriam: Dr. Gary A. Dudley (1952-2006) a modern pioneer in the study of muscle and resistance training.

Dr. Gary Alton Dudley was a modern pioneer in the study of muscle. His work encompassed almost 30 years of study with dramatic discoveries in the areas of muscle physiology, resistance training, and spinal cord injury and therapy. The greater understanding of muscle fiber changes with training, as well as novel experiments using magnetic resonance imaging and single fiber analyses, allowed for many discoveries in the areas of resistance training and detraining, the roles of electrical stimulation in training muscle, the compatibility of different exercise modes, and the characteristics of and treatment interventions for spinal cord injury. His work and insights will provide future investigators a knowledge base from which to work for both basic and applied research in muscle and exercise physiology.

Research in Exercise Physiology and Dyspnea at McMaster University

Dr EJ Moran Campbell arrived in Hamilton, Ontario, in September 1968, as the founding chairman of the Department of Medicine at McMaster University Medical Centre (Hamilton, Ontario). He had asked me to be the Head of the Regional Respiratory Program, and I followed him two weeks later. We had worked together at the Royal Postgraduate Medical School, Hammersmith Hospital, for several years to develop a system of exercise testing that could be routinely applied to any clinical problem associated with effort intolerance. We also each had our own separate obsessions; Moran’s obsession was in dyspnea, and mine was in exercise metabolism. The three research streams – exercise testing, metabolism and dyspnea – gradually gained momentum, largely due to the hard work of graduate students and fellows. In the present brief overview, I hope to acknowledge their contribution as much as the progress we made in these topics.

The Validity and Reliability of Intestinal Temperature during Intermittent Running

In many sporting and occupational settings, measuring core temperature using invasive methods is not practical. In these circumstances, ingestible temperature sensor capsules are a promising alternative. To date, no researcher has investigated the validity of intestinal temperature (T(int)) during free running or examined the between-trial reproducibility of this technique. Therefore, in two investigations, we examined the validity and reliability of Tint during prolonged intermittent shuttle running. In investigation A, 10 male games players completed 60 min of exercise while their rectal temperature (T(rec)) and T(int) were monitored. In investigation B, Tint was measured while nine males undertook two 90-min bouts of exercise, separated by 7 d. A mean systematic bias of -0.15 degrees C (95% CI, 0.10-0.20) was found between T(int) and T(rec) during exercise. This bias for T(int) to record higher temperatures than T(rec) was uniform through the range of measurements, such that the exercise-mediated changes in body temperature were similar between methods of measurement. The 95% limits of agreement were found to be +/- 0.22 degrees C (95% CI, 0.11-0.33) and correlations were high (r > 0.85), suggesting that random error between methods was acceptably small. In investigation B, the mean change between repeated trials was a negligible 0.01 degrees C (95% CI, -0.02 to 0.05). The within-subjects SD was 0.08 degrees C (95% CI, 0.05-0.15). Random error was uniform through the measurement range and was deemed acceptable on the basis of statistical power calculations. These findings suggest that the test-retest variability of Tint is acceptably small during intermittent shuttle running. The small amount of random measurement error and similar thermal responses to exercise suggest that Tint is as appropriate for use in exercise physiology research as T(rec), provided that the consistent bias between these measurement methods is allowed for.

The reliability of the i-STAT clinical portable analyser

The purpose of this investigation was to assess the reliability of the i-STAT clinical portable analyser and CG(4)(+) cartridge measures of blood pH, partial pressures of O(2) (pO(2)) and CO(2) (pCO(2)), bicarbonate ([HCO(3)(-)]), base excess (BE), total carbon dioxide (TCO(2)), oxygen saturation (sO(2)) and blood lactate ([BLa(-)]) at various exercise intensities. A comparison between [BLa(-)] measured by the i-STAT and the Accusport lactate analysers during an intermittent treadmill run was also undertaken. The technical error of measurement (TEM%) at rest, at moderate (200W) and maximal exercise (V O(2)max) was acceptable (<15%) for all parameters. The intra-class correlation coefficients for each analyte ranged from weak-to-strong across resting (ICC=0.19-0.96) and moderate (ICC=0.30-0.96) exercise intensities. The ICC for all analytes were observed to be strong following maximal intensity exercise (ICC=0.77-0.95). The comparison of the [BLa(-)] measures between the i-STAT and Accusport showed that the difference between measures was acceptable at both low (<4mmolL(-1)) (-0.39+/-0.27mmolL(-1)), moderate to high concentrations (>4mmolL(-1)) (0.58+/-1.22mmolL(-1)), and across all [BLa(-)] data (0.36+/-1.13mmolL(-1)). In conclusion, the i-STAT clinical analyser and CG(4)(+) cartridge provides reliable measures of a number of blood parameters across exercise intensities. The [BLa(-)] measures from the i-STAT analyser are consistent with that of the Accusport lactate analyser.

Challenges for Future Research in Exercise Physiology as Applied to the Respiratory System

Some of the major unresolved questions in the respiratory physiology and pathophysiology of exercise are addressed. To solve many of these difficult basic problems and to understand how systems operate alone and in combination in an integrated fashion, truly experimental integrative physiological approaches are required in both humans and animals.