Gordon O. Matheson

All Publications

• Call to Action on Making Physical Activity Assessment and Prescription a Medical Standard of Care CURRENT SPORTS MEDICINE REPORTS Sallis, R. E., Matuszak, J. M., Baggish, A. L., Franklin, B. A., Chodzko-Zajko, W., Fletcher, B. J., Gregory, A., Joy, E., Matheson, G., McBride, P., Puffer, J. C., Trilk, J., Williams, J. 2016; 15 (3): 207-214

  Abstract

  The U.S. population is plagued by physical inactivity, lack of cardiorespiratory fitness, and sedentary lifestyles, all of which are strongly associated with the emerging epidemic of chronic disease. The time is right to incorporate physical activity assessment and promotion into health care in a manner that engages clinicians and patients. In April 2015, the American College of Sports Medicine and Kaiser Permanente convened a joint consensus meeting of subject matter experts from stakeholder organizations to discuss the development and implementation of a physical activity vital sign (PAVS) to be obtained and recorded at every medical visit for every patient. This statement represents a summary of the discussion, recommendations, and next steps developed during the consensus meeting. Foremost, it is a "call to action" for current and future clinicians and the health care community to implement a PAVS in daily practice with every patient.

  View details for DOI 10.1249/JSR.0000000000000249

  View details for Web of Science ID 000376660400016

  View details for PubMedID 27172086

• Injuries and Illnesses in the Preparticipation Evaluation Data of 1693 College Student-Athletes AMERICAN JOURNAL OF SPORTS MEDICINE Matheson, G. O., Anderson, S., Robell, K. 2015; 43 (6): 1518-1525

  Abstract

  While the preparticipation evaluation (PPE) is widely used by medical practitioners, its overall effectiveness is unknown, in part because there are no standardized or centralized mechanisms to collect and analyze medical history information.To report on the injuries and illnesses identified with the use of an electronic PPE (ePPE) completed by first-time National Collegiate Athletic Association Division 1 varsity sport participants (N = 1693; 797 women, 896 men) upon entry to a single institution between 2010 and 2013.Cross-sectional study; Level of evidence, 3.In total, 3126 discrete past injuries were reported (women, 1473 injuries; men, 1653 injuries). Time loss from sport participation averaged 31.4 days for each injury (women, 32.2 days; men, 30.7 days), and aggregate time loss from sport for all student-athletes before the ePPE was 256 years. Eleven percent of student-athletes had injuries that were unresolved and still symptomatic at the time of the ePPE. Thirty percent of injured student-athletes had a history of ≥1 surgeries for an injury (women, 176; men, 213), and these accounted for 57% of the time lost from sport before college participation. Head injuries accounted for 9% (110 women, 173 men), and loss of consciousness was reported in 19% of these. One in 3 student-athletes answered "yes" to ≥1 of the American Heart Association questions on cardiovascular health. While 15% of women reported a history of stress fracture, only 3% reported a diagnosed eating disorder.While some data in this population are self-evident, we were not aware of the high frequency of past injuries, the magnitude of time lost from sport, the high frequency of past surgery, and the number of participants still symptomatic from injuries. The ePPE is a valuable tool for collecting and analyzing aggregate injury and illness data in athletes, such as the finding that 11% of injuries that were reported were unresolved and still symptomatic.

  View details for DOI 10.1177/0363546515572144

  View details for Web of Science ID 000355379200030

  View details for PubMedID 25767268

• Leveraging Human-Centered Design in Chronic Disease Prevention AMERICAN JOURNAL OF PREVENTIVE MEDICINE Matheson, G. O., Pacione, C., Shultz, R. K., Kluegl, M. 2015; 48 (4): 472-479

  Abstract

  Bridging the knowing-doing gap in the prevention of chronic disease requires deep appreciation and understanding of the complexities inherent in behavioral change. Strategies that have relied exclusively on the implementation of evidence-based data have not yielded the desired progress. The tools of human-centered design, used in conjunction with evidence-based data, hold much promise in providing an optimal approach for advancing disease prevention efforts. Directing the focus toward wide-scale education and application of human-centered design techniques among healthcare professionals will rapidly multiply their effective ability to bring the kind of substantial results in disease prevention that have eluded the healthcare industry for decades. This, in turn, would increase the likelihood of prevention by design.

  View details for DOI 10.1016/j.amepre.2014.10.014

  View details for Web of Science ID 000351251000014

  View details for PubMedID 25700655

• 2014 Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad: 1st International Conference held in San Francisco, California, May 2012 and 2nd International Conference held in Indianapolis, Indiana, May 2013 BRITISH JOURNAL OF SPORTS MEDICINE De Souza, M. J., Nattiv, A., Joy, E., Misra, M., Williams, N. I., Mallinson, R. J., Gibbs, J. C., Olmsted, M., Goolsby, M., Matheson, G. 2014; 48 (4)

  Abstract

  The Female Athlete Triad is a medical condition often observed in physically active girls and women, and involves three components: (1) low energy availability with or without disordered eating, (2) menstrual dysfunction and (3) low bone mineral density. Female athletes often present with one or more of the three Triad components, and an early intervention is essential to prevent its progression to serious endpoints that include clinical eating disorders, amenorrhoea and osteoporosis. This consensus statement represents a set of recommendations developed following the 1st (San Francisco, California, USA) and 2nd (Indianapolis, Indiana, USA) International Symposia on the Female Athlete Triad. It is intended to provide clinical guidelines for physicians, athletic trainers and other healthcare providers for the screening, diagnosis and treatment of the Female Athlete Triad and to provide clear recommendations for return to play. The 2014 Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad expert panel has proposed a risk stratification point system that takes into account magnitude of risk to assist the physician in decision-making regarding sport participation, clearance and return to play. Guidelines are offered for clearance categories, management by a multidisciplinary team and implementation of treatment contracts. This consensus paper has been endorsed by the Female Athlete Triad Coalition, an International Consortium of leading Triad researchers, physicians and other healthcare professionals, the American College of Sports Medicine and the American Medical Society for Sports Medicine.

  View details for DOI 10.1136/bjsports-2013-093218

  View details for Web of Science ID 000331185400005

  View details for PubMedID 24463911

• Team Clinician Variability in Return-to-Play Decisions. Clinical journal of sport medicine Shultz, R., Bido, J., Shrier, I., Meeuwisse, W. H., Garza, D., Matheson, G. O. 2013; 23 (6): 456-461

  Abstract

  To describe the variability in the return-to-play (RTP) decisions of experienced team clinicians and to assess their clinical opinion as to the relevance of 19 factors described in a RTP decision-making model.Survey questionnaire.Advanced Team Physician Course.Sixty seven of 101 sports medicine clinicians completed the questionnaire.Results were analyzed using descriptive statistics. For categorical variables, we report percentage and frequency. For continuous variables, we report mean (SD) if data were approximately normally distributed and frequencies for clinically relevant categories for skewed data.The average number of years of clinical sports medicine experience was 13.6 (9.8). Of the 62 clinicians who responded fully, 35% (n = 22) would "clear" (vs "not clear") an athlete to participate in sport even if the risk of an acute reinjury or long-term sequelae is increased. When respondents were given 6 different RTP options rather than binary choices, there were increased discrepancies across some injury risk scenarios. For example, 8.1% to 16.1% of respondents who chose to clear an athlete when presented with binary choices, later chose to "not clear" an athlete when given 6 graded RTP options. The respondents often considered factors of potential importance to athletes as nonimportant to the RTP decision process if risk of reinjury was unaffected (range, n = 4 [10%] to n = 19 [45%]).There is a high degree of variability in how different clinicians weight the different factors related to RTP decision making. More precise definitions decrease but do not eliminate this variability.

  View details for DOI 10.1097/JSM.0b013e318295bb17

  View details for PubMedID 23797160

• Prevention and management of non-communicable disease: the IOC consensus statement, Lausanne 2013 BRITISH JOURNAL OF SPORTS MEDICINE Matheson, G. O., Kluegl, M., Engebretsen, L., Bendiksen, F., Blair, S. N., Borjesson, M., Budgett, R., Derman, W., Erdener, U., Ioannidis, J. P., Khan, K. M., Martinez, R., van Mechelen, W., Mountjoy, M., Sallis, R. E., Schwellnus, M., Shultz, R., Soligard, T., Steffen, K., Sundberg, C. J., Weiler, R., Ljungqvist, A. 2013; 47 (16): 1003-U56

  Abstract

  Morbidity and mortality from preventable, non-communicable chronic disease (NCD) threatens the health of our populations and our economies. The accumulation of vast amounts of scientific knowledge has done little to change this. New and innovative thinking is essential to foster new creative approaches that leverage and integrate evidence through the support of big data, technology and design thinking. The purpose of this paper is to summarise the results of a consensus meeting on NCD prevention sponsored by the IOC in April 2013. Within the context of advocacy for multifaceted systems change, the IOC's focus is to create solutions that gain traction within healthcare systems. The group of participants attending the meeting achieved consensus on a strategy for the prevention and management of chronic disease that includes the following: (1) Focus on behavioural change as the core component of all clinical programmes for the prevention and management of chronic disease. (2) Establish actual centres to design, implement, study and improve preventive programmes for chronic disease. (3) Use human-centred design in the creation of prevention programmes with an inclination to action, rapid prototyping and multiple iterations. (4) Extend the knowledge and skills of Sports and Exercise Medicine (SEM) professionals to build new programmes for the prevention and treatment of chronic disease focused on physical activity, diet and lifestyle. (5) Mobilise resources and leverage networks to scale and distribute programmes of prevention. True innovation lies in the ability to align thinking around these core strategies to ensure successful implementation of NCD prevention and management programmes within healthcare. The IOC and SEM community are in an ideal position to lead this disruptive change. The outcome of the consensus meeting was the creation of the IOC Non-Communicable Diseases ad hoc Working Group charged with the responsibility of moving this agenda forward.

  View details for DOI 10.1136/bjsports-2013-093034

  View details for Web of Science ID 000325530900002

  View details for PubMedID 24115479

• Responsibility of sport and exercise medicine in preventing and managing chronic disease: applying our knowledge and skill is overdue BRITISH JOURNAL OF SPORTS MEDICINE Matheson, G. O., Kluegl, M., Dvorak, J., Engebretsen, L., Meeuwisse, W. H., Schwellnus, M., Blair, S. N., van Mechelen, W., Derman, W., Borjesson, M., Bendiksen, F., Weiler, R. 2011; 45 (16): 1272-1282

  Abstract

  The rapidly increasing burden of chronic disease is difficult to reconcile with the large, compelling body of literature that demonstrates the substantial preventive and therapeutic benefits of comprehensive lifestyle intervention, including physical activity, smoking cessation and healthy diet. Physical inactivity is now the fourth leading independent risk factor for death caused by non-communicable chronic disease. Although there have been efforts directed towards research, education and legislation, preventive efforts have been meager relative to the magnitude of the problem. The disparity between our scientific knowledge about chronic disease and practical implementation of preventive approaches now is one of the most urgent concerns in healthcare worldwide and threatens the collapse of our health systems unless extraordinary change takes place.The authors believe that there are several key factors contributing to the disparity. Reductionism has become the default approach for healthcare delivery, resulting in fragmentation rather than integration of services. This, in turn, has fostered a disease-based rather than a health-based model of care and has produced medical school curricula that no longer accurately reflect the actual burden of disease. Trying to 'fit' prevention into a disease-based approach has been largely unsuccessful because the fundamental tenets of preventive medicine are diametrically opposed to those of disease-based healthcare.A clinical discipline within medicine is needed to adopt disease prevention as its own reason for existence. Sport and exercise medicine is well positioned to champion the cause of prevention by promoting physical activity.This article puts forward a strong case for the immediate, increased involvement of clinical sport and exercise medicine in the prevention and treatment of chronic disease and offers specific recommendations for how this may begin.

  View details for DOI 10.1136/bjsports-2011-090328

  View details for Web of Science ID 000297688500005

  View details for PubMedID 21948123

• The Prevention of Sport Injury: An Analysis of 12 000 Published Manuscripts CLINICAL JOURNAL OF SPORT MEDICINE Kluegl, M., Shrier, I., McBain, K., Shultz, R., Meeuwisse, W. H., Garza, D., Matheson, G. O. 2010; 20 (6): 407-412

  View details for DOI 10.1097/JSM.0b013e3181f4a99c

  View details for Web of Science ID 000284379100004

• Return-to-Play in Sport: A Decision-based Model CLINICAL JOURNAL OF SPORT MEDICINE Creighton, D. W., Shrier, I., Shultz, R., Meeuwisse, W. H., Matheson, G. O. 2010; 20 (5): 379-385

  Abstract

  Return-to-play (RTP) decisions are fundamental to the practice of sports medicine but vary greatly for the same medical condition and circumstance. Although there are published articles that identify individual components that go into these decisions, there exists neither quantitative criteria nor a model for the sequence or weighting of these components within the medical decision-making process. Our objective was to develop a decision-based model for clinical use by sports medicine practitioners.English literature related to RTP decision making.We developed a 3-step decision-based RTP model for an injury or illness that is specific to the individual practitioner making the RTP decision: health status, participation risk, and decision modification. In Step 1, the Health Status of the athlete is assessed through the evaluation of Medical Factors related to how much healing has occurred. In Step 2, the clinician evaluates the Participation Risk associated with participation, which is informed by not only the current health status but also by the Sport Risk Modifiers (eg, ability to protect the injury with padding, athlete position). Different individuals are expected to have different thresholds for "acceptable level of risk," and these thresholds will change based on context. In Step 3, Decision Modifiers are considered and the decision to RTP or not is made.Our model helps clarify the processes that clinicians use consciously and subconsciously when making RTP decisions. Providing such a structure should decrease controversy, assist physicians, and identify important gaps in practice areas where research evidence is lacking.

  View details for DOI 10.1097/JSM.0b013e3181f3c0fe

  View details for Web of Science ID 000281559200012

  View details for PubMedID 20818198

• The International Olympic Committee (IOC) Consensus Statement on Periodic Health Evaluation of Elite Athletes, March 2009 CLINICAL JOURNAL OF SPORT MEDICINE Ljungqvist, A., Jenoure, P. J., Engebretsen, L., Alonso, J. M., Bahr, R., Clough, A. F., de Bondt, G., Dvorak, J., Maloley, R., Matheson, G., Meeuwisse, W., Meijboom, E. J., Mountjoy, M., Pelliccia, A., Schwellnus, M., Sprumont, D., Schamasch, P., Gauthier, J., Dubi, C. 2009; 19 (5): 347-360

  View details for Web of Science ID 000269714200002

  View details for PubMedID 19741306

• Exercise and prostate cancer SPORTS MEDICINE Torti, D. C., Matheson, G. O. 2004; 34 (6): 363-369

  Abstract

  Prostate cancer is a leading cause of cancer morbidity and mortality in men. In addition to improved treatments, strategies to reduce disease risk are urgently required. This review summarises the literature that examines the association between exercise and prostate cancer risk. Between 1989 and 2001, 13 cohort studies were conducted in the US and internationally. Of these, nine showed an association between exercise and decreased prostate cancer risk. Five of 11 case-control studies conducted between 1988 and 2002 reported an association between decreased risk of prostate cancer and high activity levels. Considering all studies performed between 1976 and 2002, 16 out of 27 studies reported reduced risk in men who were most active; in nine out of 16 studies the reduction in risk was statistically significant. Average risk reduction ranged from 10-30%. In aggregate, this evidence suggests a probable link between increased physical exercise and decreased prostate cancer risk. The ability of exercise to modulate hormone levels, prevent obesity, enhance immune function and reduce oxidative stress have all been postulated as mechanisms that may underlie the protective effect of exercise. Exercise may also be of benefit in men undergoing treatment for prostate cancer. Overall, study design and control of potential confounding factors varied greatly among studies, possibly contributing to the variation in results. Epidemiological studies that are better controlled, larger in scale and more carefully designed may help to more fully clarify the relationship between exercise and prostate cancer. In addition, intervention trials that test whether exercise programmes can reduce prostate cancer risk are currently underway to rigorously test the ability of exercise to reduce prostate cancer incidence.

  View details for Web of Science ID 000222047500003

  View details for PubMedID 15157121

• The lactate paradox in human high-altitude physiological performance NEWS IN PHYSIOLOGICAL SCIENCES Hochachka, P. W., Beatty, C. L., Burelle, Y., Trump, M. E., McKenzie, D. C., Matheson, G. O. 2002; 17: 122-126

  Abstract

  For many years, physiologists have puzzled over the observation that, during maximum aerobic exercise, high-altitude natives generate lower-than-expected amounts of lactate; the higher the altitude, the lower the postexercise blood lactate peak. This paradoxical situation may be caused mainly by upregulated metabolic control contributions from cell ATP demand and ATP supply pathways.

  View details for DOI 10.1152/nips.01382.2001

  View details for Web of Science ID 000176260400007

  View details for PubMedID 12021383

• Failure and fatigue characteristics of adhesive athletic tape MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Bragg, R. W., MacMahon, J. M., Overom, E. K., Yerby, S. A., Matheson, G. O., Carter, D. R., Andriacchi, T. P. 2002; 34 (3): 403-410

  Abstract

  Athletic tape has been commonly reported to lose much of its structural support after 20 min of exercise. Although many studies have addressed the functional performance characteristics of athletic tape, its mechanical properties are poorly understood. This study examines the failure and fatigue properties of several commonly used athletic tapes.A Web-based survey of professional sports trainers was used to select the following three tapes for the study: Zonas (Johnson & Johnson), Leukotape (Beiersdorf), and Jaylastic (Jaybird & Mais). Using a hydraulic material testing system (MTS), eight samples of each tape were compared in three different mechanical tests: load-to-failure, fatigue testing under load control, and fatigue testing under displacement control. Differences in tape microstructure were used to interpret the results of the mechanical tests.Significant differences (P < 0.001) in failure load, elongation at failure, and stiffness were found from failure tests. Significant differences were also found (P < 0.001) in fatigue behavior under both modes of control. As a representative example, in one normalized displacement control fatigue test after 20 min of cycling, 21% (Zonas), 29% (Leukotape), and 57% (Jaylastic) of the mechanical support was lost. After cycling, all tapes loaded to failure showed increased stiffness (P < 0.001), indicating significant energy absorption during cycling. Observed differences in the tapes' microstructure were qualitatively consistent with the measured differences in their mechanical properties.In understanding the shortcomings of currently available tapes, the results of these tests can now be used as benchmarks with which to compare and develop future tape designs. Ultimately, these improved tapes should reduce ankle injuries among athletes.

  View details for Web of Science ID 000174268300004

  View details for PubMedID 11880802

• A comprehensive and cost-effective preparticipation exam implemented on the World Wide Web MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Peltz, J. E., Haskell, W. L., Matheson, G. O. 1999; 31 (12): 1727-1740

  Abstract

  Mandatory preparticipation examinations (PPE) are labor intensive, offer little routine health maintenance and are poor predictors of future injury or illness. Our objective was to develop a new PPE for the Stanford University varsity athletes that improved both quality of primary and preventive care and physician time efficiency. This PPE is based on the annual submission, by each athlete, of a comprehensive medical history questionnaire that is then summarized in a two-page report for the examining physician. The questionnaire was developed through a search of MEDLINE from 1966 to 1997, review of PPE from 11 other institutions, and discussion with two experts from each of seven main content areas: medical and musculoskeletal history, eating, menstrual and sleep disorders, stress and health risk behaviors. Content validity was assessed by 10 sports medicine physicians and four epidemiologists. It was then programmed for the World Wide Web (http:// www.stanford.edu/dept/sportsmed/). The questionnaire demonstrated a 97 +/- 2% sensitivity in detecting positive responses requiring physician attention. Sixteen physicians administered the 1997/98 PPE; using the summary reports, 15 found improvement in their ability to provide overall medical care including health issues beyond clearance; 13 noted a decrease in time needed for each athlete exam. Over 90% of athletes who used the web site found it "easy" or "moderately easy" to access and complete. Initial assessment of this new PPE format shows good athlete compliance, improved exam efficiency and a strong increase in subjective physician satisfaction with the quality of screening and medical care provided. The data indicate a need for improvement of routine health maintenance in this population. The database offers opportunities to study trends, risk factors, and results of interventions.

  View details for Web of Science ID 000084247100007

  View details for PubMedID 10613422

• Preparticipation screening of athletes JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Matheson, G. O. 1998; 279 (22): 1829-1830

  View details for Web of Science ID 000073998500039

  View details for PubMedID 9628718

• Achilles tendonitis: Are corticosteroid injections useful or harmful? CLINICAL JOURNAL OF SPORT MEDICINE Shrier, I., Matheson, G. O., Kohl, H. W. 1996; 6 (4): 245-250

  Abstract

  The use of local corticosteroid injections for the treatment of Achilles tendonitis is controversial. Some authors advocate their use based on efficacy in accelerating the healing process of Achilles tendonitis; others feel the associated side effects should preclude their use altogether. The purpose of this study was to comprehensively review and critically appraise the available literature in order to examine the evidence concerning this clinical dilemma.MEDLINE was searched using MeSH and textwords for English- and French-language articles related to Achilles tendonitis and corticosteroids published since 1966. Additional references were reviewed from the bibliographies of the retrieved articles. The total number of articles reviewed was 145.All clinical study designs were included as well as related animal studies using experimental and quasi-experimental designs.In reviewing the literature, particular attention was paid to the relative strengths of the different study designs. From these data, the factors associated with effectiveness and safety of injected corticosteroids were examined.The only rigorous studies (one randomized controlled trial, one cohort study) showed no benefit of corticosteroids over placebo. In animal studies, corticosteroid injections decrease adhesion formation, temporarily weaken the tendon if given intratendinously, but have no effect on tendon strength if injected into the paratenon. The overall incidence of side effects with locally injected corticosteroids is approximately 1%. Most side effects are temporary, but skin atrophy and depigmentation can be permanent. Although there are many case reports of Achilles tendon rupture following local corticosteroid injection, there are no published rigorous studies that evaluate the risk of rupture with or without corticosteroid injection.There are insufficient published data to determine the comparative risks and benefits of corticosteroid injections in Achilles tendonitis. The decreased tendon strength with intratendinous injections in animal studies suggests that rupture may be a potential complication for several weeks following injection.

  View details for Web of Science ID A1996VH09600007

  View details for PubMedID 8894337

• TRAINING AND CLINICAL COMPETENCE IN MUSCULOSKELETAL MEDICINE - IDENTIFYING THE PROBLEM SPORTS MEDICINE Craton, N., Matheson, G. O. 1993; 15 (5): 328-337

  Abstract

  Injuries and diseases of the musculoskeletal system account for more than 20% of patient visits to primary care and emergency medical practitioners. However, less than 3% of the pre-clinical medical school curriculum is devoted to teaching all aspects of musculoskeletal disease, and only 12% of medical schools require mandatory training in musculoskeletal medicine during the clinical years of undergraduate medical education in Canada. Available elective training in musculoskeletal injuries and diseases is commonly taught by hospital-affiliated physicians and surgeons, with the result that this teaching case load is typically skewed towards serious and/or surgical problems. The disparity between the clinical competence required for musculoskeletal problems in clinical practice and the content and format of medical education has not yet been addressed by changes in medical school curricula. One of the reasons for this is that the available morbidity statistics, which provide data regarding the frequency of specific musculoskeletal diagnoses, are based on diagnostic codes which are imprecise and incomplete. This prohibits the accurate selection of course content in this area, which is among the first steps in the development of a curriculum.

  View details for Web of Science ID A1993LA77000004

  View details for PubMedID 8321946

• REGULATING ATP TURNOVER RATES OVER BROAD DYNAMIC WORK RANGES IN SKELETAL-MUSCLES JOURNAL OF APPLIED PHYSIOLOGY Hochachka, P. W., Matheson, G. O. 1992; 73 (5): 1697-1703

  Abstract

  It has long been appreciated that rates of ATP utilization and production need to be extremely closely balanced. To put it in molecular rather than molar terms, in human muscle engaged in a 15-min work protocol, approximately 3.3 x 10(20) ATP/g are used and resynthesized at approximately 100 times the resting cycling rates before fatigue, during which time only a 20-25% decrease in the ATP pool is sustained. Analysis of how such remarkable regulatory precision is achieved suggests that in resting muscle myosin behaves as a latent catalyst whose full catalytic potential 1) is realized with the arrival of an activator signal (Ca2+) and 2) is tempered with reaction products; such proactive control, initiated at ATP utilization, sets the required flux through ATP-producing pathways. For any given enzyme step in ATP-producing pathways, reaction velocity (v) becomes the independent parameter, with substrate concentration ([S], the dependent parameter) being adjusted accordingly. Because the dynamic range for muscles (change from resting to maximum ATP turnover rates) can exceed 100-fold, in many studies of working muscle the percent change in ATP turnover rate exceeds (sometimes by very large margins) the percent change in [S]. These observations are not easily explained by current metabolic regulation models but are consistent with pathway enzymes behaving as latent catalysts in resting muscle. In this view, the unmasking of such latent catalytic potential is the main explanation for how large changes in v can be achieved with modest (sometimes immeasurable) changes in [S].(ABSTRACT TRUNCATED AT 250 WORDS)

  View details for Web of Science ID A1992JZ59600001

  View details for PubMedID 1474039

• P-31 NMR OF ELECTRICALLY STIMULATED RECTUS FEMORIS MUSCLE - AN INVIVO GRADED-EXERCISE MODEL MAGNETIC RESONANCE IN MEDICINE Matheson, G. O., McKenzie, D. C., Gheorghiu, D., ELLINGER, D. C., Quinney, H. A., Allen, P. S. 1992; 26 (1): 60-70

  Abstract

  This study reports on the development of a model for studying skeletal muscle metabolism in humans using NMR spectroscopy. Graded exercise was simulated using electrical stimulation in 10 healthy, fit subjects (mean VO2max = 53 +/- 4 ml.kg-1.min-1). The effects of varying the stimulation parameters, namely, the stimulation frequency, the stimulation intensity, and the duty cycle, as well as the spectral interrogation volume, were compared using data acquired from the rectus femoris muscle. With stimulation, the inorganic phosphate to phosphocreatine concentration ratio ([P(i)]/[PCr]) and the intracellular pH both follow curvilinear relationships over the stimulation frequencies from 3 to 30 Hz, with the magnitude of the observed change related closely to stimulation intensity and duty cycle. Oxidative phosphorylation predominates at stimulation frequencies below 12 Hz, while anaerobic metabolism increases sharply above 12 Hz. Our findings show clearly the interdependence of the effects of the various stimulation parameters and emphasize the care that must be exercised in interpreting the physiological significance of the biochemical data obtained from electrical stimulation models used to study skeletal muscle metabolism.

  View details for Web of Science ID A1992JB37700006

  View details for PubMedID 1625567

• SKELETAL-MUSCLE METABOLISM AND WORK CAPACITY - A P-31-NMR STUDY OF ANDEAN NATIVES AND LOWLANDERS JOURNAL OF APPLIED PHYSIOLOGY Matheson, G. O., Allen, P. S., ELLINGER, D. C., Hanstock, C. C., Gheorghiu, D., McKenzie, D. C., Stanley, C., Parkhouse, W. S., Hochachka, P. W. 1991; 70 (5): 1963-1976

  Abstract

  Two metabolic features of altitude-adapted humans are the maximal O2 consumption (VO2max) paradox (higher work rates following acclimatization without increases in VO2max) and the lactate paradox (progressive reductions in muscle and blood lactate with exercise at increasing altitude). To assess underlying mechanisms, we studied six Andean Quechua Indians in La Raya, Peru (4,200 m) and at low altitude (less than 700 m) immediately upon arrival in Canada. The experimental strategy compared whole-body performance tests and single (calf) muscle work capacities in the Andeans with those in groups of sedentary, power-trained, and endurance-trained lowlanders. We used 31P nuclear magnetic resonance spectroscopy to monitor noninvasively changes in concentrations of phosphocreatine [( PCr]), [Pi], [ATP], [PCr]/[PCr] + creatine ([Cr]), [Pi]/[PCr] + [Cr], and pH in the gastrocnemius muscle of subjects exercising to fatigue. Our results indicate that the Andeans 1) are phenotypically unique with respect to measures of anaerobic and aerobic work capacity, 2) despite significantly lower anaerobic capacities, are capable of calf muscle work rates equal to those of highly trained power- and endurance-trained athletes, and 3) compared with endurance-trained athletes with significantly higher VO2max values and power-trained athletes with similar VO2max values, display, respectively, similar and reduced perturbation of all parameters related to the phosphorylation potential and to measurements of [Pi], [PCr], [ATP], and muscle pH derivable from nuclear magnetic resonance. Because the lactate paradox may be explained on the basis of tighter ATP demand-supplying coupling, we postulate that a similar mechanism may explain 1) the high calf muscle work capacities in the Andeans relative to measures of whole-body work capacity, 2) the VO2max paradox, and 3) anecdotal reports of exceptional work capacities in indigenous altitude natives.

  View details for Web of Science ID A1991FL02400011

  View details for PubMedID 1864776

• MUSCULOSKELETAL INJURIES ASSOCIATED WITH PHYSICAL-ACTIVITY IN OLDER ADULTS MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Matheson, G. O., Macintyre, J. G., Taunton, J. E., Clement, D. B., LLOYDSMITH, R. 1989; 21 (4): 379-385

  Abstract

  In order to compare the clinical presentation of overuse injuries in older and younger athletes, retrospective patient chart data were obtained from cases which had been referred to an outpatient sports medicine clinic over a 5-yr period. A total of 1,407 cases were studied comprising two populations separated by significantly (P less than 0.001) different ages: 685 "old" (mean age = 56.9 +/- 6.1 yr) and 722 "young" (mean age = 30.4 +/- 8.1 yr). Although the two subpopulations demonstrated modest differences in sport activity at the time of injury, specific diagnoses, and anatomic location of injury, many similarities existed between the groups. Running, fitness classes, and field sports were more commonly associated with injury in the younger group, while racquet sports, walking, and low intensity sports were more commonly associated with injury in the older group. The frequency of tendinitis was similar in both age groups, while metatarsalgia, plantar fasciitis, and meniscal injury were more common in the older population, and patellofemoral pain syndrome (PFPS) and stress fracture/periostitis were more common in the younger population. Anatomically, injury sites in the foot were more frequent in the older group, while injury sites in the knee were more frequent in the younger group. In the older population, the prevalence of osteoarthritis was 2.5 times higher than the frequency of osteoarthritis as the source of activity-related pain. In the older group, 85% of the diagnoses were overuse injuries known to respond to conservative treatment, 14.4% of the cases required consultative referral, and only 4.1% required surgery.

  View details for Web of Science ID A1989AJ73500007

  View details for PubMedID 2674589

• STRESS-FRACTURES IN ATHLETES - A STUDY OF 320 CASES AMERICAN JOURNAL OF SPORTS MEDICINE Matheson, G. O., Clement, D. B., McKenzie, D. C., Taunton, J. E., LLOYDSMITH, D. R., Macintyre, J. G. 1987; 15 (1): 46-58

  Abstract

  We analyzed cases of 320 athletes with bone scan-positive stress fractures (M = 145, F = 175) seen over 3.5 years and assessed the results of conservative management. The most common bone injured was the tibia (49.1%), followed by the tarsals (25.3%), metatarsals (8.8%), femur (7.2%), fibula (6.6%), pelvis (1.6%), sesamoids (0.9%), and spine (0.6%). Stress fractures were bilateral in 16.6% of cases. A significant age difference among the sites was found, with femoral and tarsal stress fractures occurring in the oldest, and fibular and tibial stress fractures in the youngest. Running was the most common sport at the time of injury but there was no significant difference in weekly running mileage and affected sites. A history of trauma was significantly more common in the tarsal bones. The average time to diagnosis was 13.4 weeks (range, 1 to 78) and the average time to recovery was 12.8 weeks (range, 2 to 96). Tarsal stress fractures took the longest time to diagnose and recover. Varus alignment was found frequently, but there was no significant difference among the fracture sites, and varus alignment did not affect time to diagnosis or recovery. Radiographs were taken in 43.4% of cases at the time of presentation but were abnormal in only 9.8%. A group of bone scan-positive stress fractures of the tibia, fibula, and metatarsals (N = 206) was compared to a group of clinically diagnosed stress fractures of the same bone groups (N = 180), and no significant differences were found. Patterns of stress fractures in athletes are different from those found in military recruits. Using bone scan for diagnosis indicates that tarsal stress fractures are much more common than previously realized. Time to diagnosis and recovery is site-dependent. Technetium99 bone scan is the single most useful diagnostic aid. Conservative treatment of stress fractures in athletes is satisfactory in the majority of cases.

  View details for Web of Science ID A1987F856600007

  View details for PubMedID 3812860