The Physics of Human Performance: An IDEAL Lab

Physics lab goes to the gymnasium, where students calculate the mechanical power required to walk on an inclined treadmill in watts and convert to units power used to measure human performance: VO2, and METs. Students learn how to use two linear regression models: the ACSM walking equation to estimate the actual power expenditure of walking and the Rockport 1 mile test to estimate their own VO2max. Students use models to prescribe exercise parameters for themselves and for two cases. The IDEAL lab collaboration is developing labs that are open, applied to life, and rigorously quantitative

Effects of an exercise programme with people living with HIV: Research in a disadvantaged setting

This study aimed to analyse the physical health effects of a community based 10-week physical activity programme with people living with HIV. It was developed, implemented and evaluated in a disadvantaged community in South Africa. A pre-post research design was chosen. Major recruitment and adherence challenges resulted in a small sample. Among the 23 participants who took part in both baseline and final testing, compliant participants (n = 12) were compared to non-compliant participants (n = 11). Immunological (CD4, viral load), anthropometric (height, weight, skinfolds and waist to hip ratio), muscular strength (h1RM) and cardiopulmonary fitness (time on treadmill) parameters were measured. The compliant and non-compliant groups were not different at baseline. Muscular strength was the parameter most influenced by compliance with the physical activity programme (F = 4.516, p = 0.047). Weight loss and improvement in cardiopulmonary fitness were restricted by the duration of the programme, compliance and influencing factors (e.g. nutrition, medication). The increase in strength is significant and meaningful in the context, as the participants goals were to look healthy and strong to avoid HIV related stigma. The improvements in appearance were a motivational factor, especially since the changes were made visible in a short time. Practical implications for health promotion are described. More research contextualised in disadvantaged settings is needed.DHE

Altered myocardial response in patients with diabetic retinopathy: an exercise echocardiography study

Additional file 1. Multivariable analysis for individual echocardiography parameters

Wpływ płci i cukrzycy typu 2 na normalizację częstości rytmu serca u pacjentów z chorobą wieńcową po rehabilitacji kardiologicznej

Introduction: The purpose of this study was to clarify whether type 2 diabetic patients with coronary disease are subject to similar benefits in heart rate recovery (HRR) as non-diabetic counterpatrs after cardiac rehabilitation, assessing men and women subjects separately. Material and methods: The data used for this analysis were from an eight-week, phase-II cardiac rehabilitation including 284 patients with ischaemic heart disease who were managed at Tehran Heart Centre between July 2004 and January 2006. The heart rate parameters were compared between diabetic and non-diabetic patients before and after cardiac rehabilitation. Diabetic and non-diabetic patients had similar age and left ventricular ejection fraction. Results: Among men, the non-diabetic patients achieved a greater improvement in peak heart rate and heart rate recovery (HRR). Additionally, lower resting heart rate was found in nondiabetic men after rehabilitation. In the women &#8805; 50 years old, there was no significant difference between diabetic and non-diabetic. The non-diabetic women < 50 years old showed significantly higher peak heart rate and HRR compared with diabetic women. Conclusions: These results indicate that the benefit of cardiac rehabilitation in HRR is significantly lower in type 2 diabetic men. Improvement of HRR is not associated with diabetic status in women &#8805; 50 years old. The response to cardiac rehabilitation in women may appear to be influenced more by age at menopause rather than diabetes mellitus.Wstęp: Celem badania było wyjaśnienie czy pacjenci z cukrzycą typu 2 i chorobą wieńcową odnoszą podobne korzyści z rehabilitacji kardiologicznej dotyczące normalizacji częstości rytmu serca (HRR, heart rate recovery) jak osoby z chorobą wieńcową bez cukrzycy. Osobno oceniano mężczyzn i kobiety. Materiał i metody: Dane wykorzystane w analizie pochodziły z 8-tygodniowego II stadium rehabilitacji kardiologicznej przeprowadzonej u 284 pacjentów z chorobą niedokrwienną serca leczonych w Tehran Heart Center w okresie pomiędzy lipcem 2004 roku a styczniem 2006 roku. Porównywano parametry opisujące częstość rytmu serca u osób z cukrzycą i bez cukrzycy, przed i po rehabilitacji kardiologicznej. Pacjenci z cukrzycą i bez cukrzycy charakteryzowali się podobnym wiekiem i zbliżoną frakcją wyrzutową lewej komory. Wyniki: U mężczyzn bez cukrzycy uzyskano większą poprawę dotyczącą szczytowej częstości rytmu serca i normalizacji HRR. Dodatkowo po rehabilitacji, u mężczyzn bez cukrzycy stwierdzono mniejszą spoczynkową częstość rytmu serca. Nie zaobserwowano znamiennych różnic pomiędzy kobietami z cukrzycą i bez cukrzycy w wieku 50 lat i starszych. Kobiety bez cukrzycy poniżej 50. roku życia charakteryzowały się istotnie większą szczytową częstością rytmu serca i HRR w porównaniu z kobietami z cukrzycą. Wnioski: Uzyskane wyniki świadczą o tym, że korzyści z rehabilitacji kardiologicznej dotyczące HRR są istotnie gorsze u mężczyzn z cukrzcą typu 2. Poprawa dotycząca HRR u kobiet w wieku 50 lat i starszych nie zależała od obecność cukrzycy. Wydaje się, że u kobiet odpowiedź na rehabilitację kardiologiczną w większym stopniu zależy od wieku, w którym wystąpiła menopauza niż od obecności cukrzycy

Lactate Threshold: Land versus Water Treadmill Running

Aquatic treadmill running has become increasingly popular for rehabilitation and training purposes due to decreased joint impact on the lower extremities, which is beneficial for special populations such as the injured, elderly, arthritic, and obese (Greene et al., 2009; Hall, Grant, Blake, Taylor, & Garbutt, 2004). Accordingly, researchers have compared key differences such as heart rate (HR), oxygen consumption (VO2), respiratory exchange ratio (RER), stride frequency, and rating of perceived exertion (RPE) between land and water running at maximal and submaximal efforts (Brubaker, Ozemek, Gonzalez, Wiley, & Collins, 2011; Rife, Myrer, Feland, Hunter, & Fellingham, 2010; Rutledge, Silvers, Browder, & Dolny, 2007; Silvers, Rutledge, & Dolny, 2007). As the benefits of aquatic treadmill running continue to be unveiled, there is an interest for healthy individuals to use the system to supplement training while limiting joint stress. Rutledge et al. (2007) revealed VO2 values at 6.5, 7.5 and 8.5 mph on an aquatic treadmill with no jet resistance to be 33.97 ± 4.0, 37.96 ± 4.0, and 43.6 ± 4.0 mL•kg-1•min-1, respectively. Watson et al. (2012) also revealed VO2 values on an aquatic treadmill at 4.5, 6.0, and 7.5 mph with no jet resistance to be 20.58 ± 3.36, 29.27 ± 3.89, and 35.77 ± 4.02 mL•kg-1•min-1, respectively. These articles demonstrate the linear relationship that exists with increasing workloads with concomitant increases in VO2 with aquatic treadmill running. As metabolic demands increase, a reliance on anaerobic metabolism ensues and the work rate at which lactate begins to accumulate in the blood is called the lactate threshold (LT) (Stainsby & Brooks, 1990). The importance of determining LT is supported by a large body of evidence to predict aerobic endurance capacity (Faude, Kindermann, & Meyer, 2009). As such, researchers have employed great efforts to predict LT via field tests to determine the correct training intensity for endurance athletes (McGehee, Tanner, & Houmard, 2005). An early study of LT revealed a strong relationship (r ≥ .91) between treadmill velocity at the onset of plasma lactate accumulation and running performance at distances ranging from 3.2 km to 42 km (Farrell, Wilmore, Coyle, Billing, and Costill, 1979). In other words, a faster sustainable work rate prior to a lactate accumulation or threshold will increase performance. Comparisons for lactate concentrations during deep water and land treadmill running have been examined previously. Frangolias and Rhodes (1996) reviewed that during submaximal intensities of deep water versus land running, at the same relative VO2 water exercise resulted in a lower HR with higher blood lactate, RER, and RPE. These same authors previously reported that at maximal efforts on land versus deep water running, there was no statistical difference between lactate concentrations 30 s and 5 min post-exercise (Frangolias & Rhodes, 1995). However, not all water immersion running studies support similar peak lactate values (Frangolias & Rhodes, 1996; Svedenhag & Seger, 1992). In a shallow water pool, a study by Town and Bradley (1991) revealed no statistical differences between land and water running for peak lactate values. However, lactate concentration in the water was 80% of that from land exercise. The authors stated that the “push-off” phase, which enabled ground contact, elicited similar running technique to land treadmills and could be partially responsible for similar physiological responses to land. In recent years the availability of aquatic treadmills allows for a more favorable comparison of land and water running due to the implication of the “push-off” phase as discussed by Town and Bradley. Silvers et al. (2007) revealed no statistical difference between peak lactate concentrations in VO2peak tests run on land versus aquatic treadmills. Zobell (2009) examined a comparison of LT between land and aquatic treadmill running which showed higher lactate levels in the water compared to land. However, no clear answers have developed as to a comparison of the LT on land vs. aquatic treadmill running. Therefore, the purpose of this study was to determine the LT while running on a land and an aquatic treadmill and compare to see if the intensities are equivalent

Relationship of Metabolic Costs of Aquatic Treadmill Versus Land Treadmill Running

Running injuries are common, usually causing athletes to cease or significantly reduce participation in a particular sport. The recent development of aquatic treadmills (ATM), an alternative to land treadmill (LTM) running, provides another option. This study sought to examine the metabolic (VO2) relationship between varying jet resistances and running speed on an ATM versus LTM. This was accomplished by developing two linear regression equations and a prediction equation. One linear regression represented the predicted VO2 from a given speed and jet resistance setting in the water, the other linear regression predicted VO2 on land from a given speed and the prediction equation was designed to match land speed to a VO2 score derived from ATM running conditions. This study examined experienced runners (N = 18). Each subject completed an initial VO2 peak test, three LTM trials, and 18 ATM trials. Each ATM trial consisted of running for three minutes at either a relatively slow, moderate, or somewhat fast speed while one of six ATM jet settings ranging from 0 to 100% jet capacity in 20% increments were assigned to the trial. Oxygen consumption (VO2) and heart rate (HR) were measured during each trial while ratings of perceived exertion (RPE) were solicited immediately following each trial. Resulting analysis produced an ATM linear regression for each jet resistance setting and a LTM linear regression equation of VO2 = 4.16 * speed + 7.39. A prediction equation for each jet resistance setting was then determined from the linear regression equations for both the ATM and LTM conditions. Results showed that at and between 0-40% jet resistances that there is not a marked difference in metabolic cost but from 40-100% jet resistances the VO2 is influenced more strongly. These results demonstrate that ATM metabolic costs are not only influenced by jet resistance settings but at jet resistances of 40% or greater provide an intensity of exercise that mimics running faster on LTM. This provides an added benefit for those individuals who may be limited due to acute overuse-type injuries or returning to full LTM activity following lower extremity surgery

Validation of VO2 Prediction Equations in Aquatic Treadmill (ATM) Exercise

The purpose of this study is to validate the accuracy of the regression models created by Greene et al. (2011) for the prediction of oxygen consumption for aquatic treadmill (ATM) exercise at different speeds and jet resistances. Twenty-one healthy individuals completed this study. Prior to testing V02peak, height, weight, and body composition were measured. At least 48 hours following V02peak testing participants completed five three-minute submaximal trials in the ATM. Speed was self-selected between 53 and 201 m-min-I to represent light, moderate, and somewhat hard conditions. Water jet.,resistance was between 0-80%. ATM speed and jet resistance were randomized for the trials. Participants rested for three minutes between trials. Oxygen consumption (V02) was measured continuously during trials. Measured V02 was compared to predicted V02. Out of 105 trials completed in the ATM, 90 resulted in a greater V02 than predicted by the Greene et al. (2011) equations. Mean and predicted V02 for all ATM trials differed by 3.6 ml - kg-I - min-I (27.7 ± 9.1 mI- kg-I - min-I vs 24.1 ± 7.2 ml - kg-I - min-I). Mean and predicted V02 for trials withjet resistance between 0-25% differed by 3.1 mI- kg-I - min-I ,(25.7 ± 7.8 vs 22.6 ± 6.8 ml - kg-I - min-I, respectively). Mean and predicted V02 for trials with 25-100% jet resistance differed by 3.8 ml- kg-I - min-I (28.5 ± 9.5 vs 24.7 ± 7.2 mI- kg-I - min-I, respectively). Paired (-test and generalized estimating equations (GEE) showed a significant correlation (p\u3c .001) between predicted and measured V O2 for both equations. There was no significant correlation (p\u3e 0.05) between V02, trial number, and BMI. Using percent-predicted value, the 0-25% equation underestimated V02 by 14% and the 25-100% equation underestimated V02 by 15%. The effect size for the 0-25 equation was .43, and the effect size for the 25-100 equation was .45. Our findings demonstrate the Greene equations underestimate V02 by an average of3.6 ml • kg-1 • min-I. This value tends to be greater than reported for previously published land treadmill (TM) running equations. Rehabilitation specialists and performance coaches may want to consider this degree of precision when using these equations for their clients

Improvement in overground walking after treadmill-based gait training in a child with agenesis of the corpus callosum

Background: Agenesis of the corpus callosum (ACC) is a rare congenital brain defect that produces a wide variety of cognitive and motor impairments. Literature regarding the response of pediatric populations with ACC to physical rehabilitation is scarce. Treadmill-based gait training (TT) has been shown to improve walking ability in some pediatric populations but has not been investigated in children with ACC. Objective: The purpose of this study was to investigate the effect of a novel treadmill intervention paradigm on the gait parameters of a child with ACC. Design: A single-participant design with 2 phases was used. Methods: The settings were the participant\u27s home and the laboratory. The participant was a 13-year-old girl who had ACC and cortical visual impairment and who ambulated independently using a reverse walker for household and short community distances. A home-based TT intervention (2 phases of 3 months of training over 6 months) was implemented, and a laboratory-based gait analysis was conducted at 4 time points: baseline, after each of the 2 training phases, and 3 months after the cessation of training. The intervention consisted of weekly bouts of TT. Phase I incorporated forward, backward, and incline walking for 15 minutes each; in phase II, this protocol was continued, but short-burst interval training for 10 minutes was added. Data collected at each laboratory visit included spatiotemporal parameters and kinematics (joint angles) during overground and treadmill walking. Results: After both phases of training, increased step length, decreased step width, and foot progression angle and decreased variability of most spatiotemporal parameters were observed for the participant. Further, after phase II, increased peak extension at the hip, knee, and ankle, decreased crouched gait, and improved minimum foot clearance during overground walking were observed. Most gait improvements were retained for 3 months after the cessation of the intervention. Limitations: The small sample size of this study and wide variety of presentations within individuals with ACC limit the generalizability of our findings. Conclusions: TT may be a safe and effective treatment paradigm for children with ACC. Future research should investigate the effect of intervention dosage on gait improvements and generalization in individuals with ACC

Prognostic relevance of exercise testing in hypertrophic cardiomyopathy

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2017Background: Resting echocardiography is fundamental in the diagnosis and monitoring of Hypertrophic Cardiomyopathy (HCM), as well as in estimating its severity. Cardiopulmonary exercise testing (CPET) is indicated to complete the evaluation of HCM patients and stress echocardiography is often used to assess symptoms. However, current guidelines still do not incorporate any type of exercise testing for risk stratification in HCM, inclusively of sudden cardiac death. Objective: The aim of this work is to review the evidence on the relevance of exercise testing in determining the prognosis in HCM. Methods: A systematic review was conducted for eligible publications, between 2010 and 2016, that included evaluation of outcomes and prognosis. In these studies, patients underwent exercise echocardiography and/or cardiopulmonary exercise testing, performed according to predefined protocols. Diverse parameters were assessed in order to determine which were relevant for the prognosis. Analysed outcomes included death from any cause (including SCD and other causes of cardiovascular death), equivalents of sudden death, heart failure requiring hospitalization or progression to New York Heart Association classes III or IV, cardiac transplantation, sustained ventricular tachycardia, stroke, myocardial infarction and need of therapy to relieve left ventricular outflow tract obstruction. Results: 12 publications were included, corresponding to a total of 4655 patients. The mean follow-up period varied between about 1 and 8 years. “Classical” risk factors for sudden death were generally present in less than half of the patients and these were not always considered predictors of long-term outcomes. The main findings of this set of studies revealed that the major predictors of outcomes were abnormal heart rate recovery, atrial fibrillation during exercise, exercise wall motion abnormalities, lower peak VO2 and higher VE/VCO2. Conclusions: Although most studies concluded that exercise testing is a safe and useful tool to determine the prognosis in HCM, further investigation on this topic, regarding the question of whether it adds independent value to the current risk stratification strategies, is needed.Introdução: A Miocardiopatia Hipertrófica (MCH) é uma doença miocárdica, na grande maioria das vezes de causa genética, por mutações em genes que codificam proteínas sarcoméricas, com um padrão de hereditariedade autossómico dominante. É uma causa comum de morte súbita cardíaca (MSC), insuficiência cardíaca (IC) e arritmias, sobretudo fibrilhação auricular (FA). Embora os doentes possam permanecer assintomáticos ou com sintomas pouco significativos durante vários anos, muitas vezes também se apresentam com capacidade reduzida para o exercício, que pode dever-se a vários mecanismos, nomeadamente a obstrução do tracto de saída do ventrículo esquerdo (OTSVE), a isquémia do miocárdio e a disfunção sistólica e/ou diastólica do ventrículo esquerdo (VE). O diagnóstico é baseado em critérios estabelecidos, tais como os da Sociedade Europeia de Cardiologia (SEC), tendo em conta sobretudo a espessura da parede ventricular esquerda (≥15 milímetros num ou mais segmentos, medidos por qualquer técnica de imagem, que não seja explicado por aumento da pós-carga). A ecocardiografia em repouso é fundamental no diagnóstico e monitorização da MCH, bem como na avaliação da severidade da doença e no prognóstico. A prova de esforço cardiorrespiratória está, neste momento, indicada para completar a avaliação dos doentes com MCH e a ecocardiografia de esforço é frequentemente utilizada com o objectivo de identificar e avaliar os sintomas. Contudo, as guidelines actuais não incorporam nenhum tipo de prova de esforço na estratificação de risco na MCH, nomeadamente de MSC. Objectivo: O objectivo deste trabalho é rever sistematicamente a evidência científica publicada sobre a relevância dos testes de esforço (tanto ecocardiográficos como da prova de esforço cardiorrespiratória), na determinação do prognóstico na MCH. Métodos: Foi realizada uma revisão sistemática com inclusão de publicações elegíveis, cujos critérios de inclusão foram: estudos prospectivos ou retrospectivos, realizados em humanos, com idade superior a 18 anos, publicados nos últimos 5 anos (entre 2010 e 2016), em língua inglesa, no qual fossem satisfeitos os critérios de diagnóstico da MCH e em que fossem realizados testes de esforço, com electrocardiograma (ECG) e/ou ecocardiograma e/ou prova de esforço cardiorrespiratória e que incluíssem outcomes e prognóstico. Nestes estudos, os doentes foram submetidos a uma avaliação clínica inicial, tendo em conta antecedentes pessoais, sintomas cardiovasculares, história familiar de MCH e/ou MSC em idade precoce, medicação habitual no momento do ensaio clínico, história de cirurgia cardíaca e/ou terapêutica médica para aliviar os sintomas de OTSVE, existência de uma janela acústica adequada para realizar ecocardiograma e a capacidade de realizar testes de esforço. A avaliação incluiu ainda, geralmente, a realização de ECG e ecocardiograma transtorácico em repouso (em modo M, bidimensional e estudo Doppler). Diversos parâmetros foram avaliados, de forma a determinar quais eram relevantes para o prognóstico: no caso do ecocardiograma, tanto em repouso como em esforço, a espessura máxima da parede ventricular esquerda, a fracção de ejecção do VE (FEVE), o gradiente de pressão máximo do tracto de saída do VE (TSVE), o movimento sistólico anterior da válvula mitral (SAM), a existência de regurgitação mitral, a sua gravidade e o seu aparecimento ou agravamento com o esforço, o diâmetro transversal da aurícula esquerda (AE), o volume indexado da AE e as alterações da contractilidade segmentar; no caso da prova de esforço cardiorrespiratória, o consumo de oxigénio no pico do esforço (VO2), a relação entre a ventilação por minuto e a produção de dióxido de carbono (VE/VCO2), a relação de trocas respiratórias no pico do esforço (rácio de trocas respiratórias), definido pelo rácio entre VCO2 e VO2 no pico do esforço e o limiar anaeróbio. Foram também avaliados, a intervalos regulares durante os testes de esforço, a frequência cardíaca e a pressão arterial. Os outcomes avaliados incluíram morte por qualquer causa (incluindo morte súbita, morte decorrente de IC progressiva ou outra), equivalentes de morte súbita (descarga apropriada de cardioversor desfibrilhador implantável – CDI – ou reanimação bem sucedida de paragem cardíaca), IC que requeresse internamento hospitalar ou progressão de classes I e II da New York Heart Association (NYHA) de IC para classes III e IV, transplante cardíaco, taquicardia ventricular mantida, acidente vascular cerebral (AVC), especialmente se no contexto de FA, enfarte do miocárdio (EM) e necessidade de terapêutica para aliviar a OTSVE. Resultados: Foram incluídas 12 publicações, correspondendo a um total de 4655 doentes. A ecocardiografia de esforço foi utilizada na maioria dos artigos seleccionados, sendo que em alguns foi associada prova cardiorrespiratória, e em dois foi apenas realizada esta última. O tempo médio de follow-up variou entre 1 e 8 anos. Os factores de risco “clássicos” para morte súbita (síncope, história familiar de MSC, taquicardia ventricular não mantida, pressão arterial (PA) com resposta anormal ao exercício e espessura da parede ventricular esquerda> 30mm) estavam presentes em menos de metade dos doentes e em dois estudos não foi comprovada associação a piores outcomes(1,2). Os principais resultados deste conjunto de estudos revelaram que os melhores preditores de outcomes foram a recuperação anormal da frequência cardíaca, FA durante o exercício, anomalias da contractilidade segmentar durante o esforço, decorrentes da ocorrência de isquémia miocárdica, o consumo máximo de oxigénio durante o exercício (VO2 no pico) (bem como a percentagem prevista de VO2 no pico) reduzido e VE/VCO2 elevado, sendo os dois últimos parâmetros relacionados com a intolerância ao esforço que, em dois dos artigos, só estavam associados a alguns dos outcomes, nomeadamente IC e transplante cardíaco, e não a MSC, provavelmente porque os mecanismos promotores de arritmia ventricular e disfunção da contractilidade são diferentes. O limiar anaeróbico reduzido não demonstrou ser tão bom preditor de outcomes como os outros dois parâmetros anteriormente referidos. A FEVE reduzida, que é um factor de risco de prognóstico cardiovascular global previamente identificado, é também relevante neste contexto. Relativamente a alguns dos parâmetros avaliados na ecocardiografia, tais como a OTSVE, os índices indirectos de disfunção diastólica (nomeadamente o diâmetro da AE) e a regurgitação mitral induzida pelo exercício, foram obtidos resultados contraditórios nos vários artigos, não permitindo concluir se estariam ou não associados a piores outcomes. Conclusões: Apesar de a maioria dos estudos ter concluído que as provas de esforço são uma ferramenta segura e útil na determinação do prognóstico da MCH, é necessária uma maior investigação relativamente ao valor adicional e eventual inclusão nas actuais estratégias de estratificação do risco