Cardiopulmonary Exercise Testing, Impedance Cardiography, and Reclassification of Risk in Patients Referred for Heart Failure Evaluation.

BACKGROUND: An impaired cardiac output response to exercise is a hallmark of chronic heart failure (HF). We determined the extent to which impedance cardiography (ICG) during exercise in combination with cardiopulmonary exercise test (CPX) responses reclassified risk for adverse events in patients with HF. METHODS AND RESULTS: CPX and ICG were performed in 1236 consecutive patients (48±15 years) evaluated for HF. Clinical, ICG and CPX variables were acquired at baseline and subjects were followed for the composite outcome of cardiac-related death, hospitalization for worsening HF, cardiac transplantation, and left ventricular assist device implantation. Cox proportional hazards analyses including clinical, noninvasive hemodynamic, and CPX variables were performed to determine their association with the composite endpoint. Net reclassification improvement (NRI) was calculated to quantify the impact of adding hemodynamic responses to a model including established CPX risk markers on reclassifying risk. There were 422 events. Among CPX variables, peak VO2 and indices of ventilatory inefficiency (VE/VCO2 slope, oxygen uptake efficiency slope) were significant predictors of risk for adverse events. Among hemodynamic variables, change in cardiac index, peak cardiac time interval, and peak left cardiac work index were the strongest predictors of risk. Having 5 impaired CPX and ICG responses to exercise yielded a sevenfold higher risk for adverse events compared with having no abnormal responses. Combining ICG responses to CPX resulted in NRIs ranging between 0.34 and 0.89, attributable to better reclassification of events. CONCLUSION: Cardiac hemodynamics determined by ICG complement established CPX measures in reclassifying risk among patients with HF.

Test-Retest Reliability of the Yo-Yo Test: A Systematic Review.

BACKGROUND: The Yo-Yo test is widely used both in the practical and research contexts; however, its true test-retest reliability remains unclear. OBJECTIVE: The present systematic review aims to identify studies that have examined the test-retest reliability of the Yo-Yo test and summarize their results. METHODS: A search of ten databases was performed to find studies that have investigated test-retest reliability of any variant of the Yo-Yo test. The COSMIN checklist was employed to assess the methodological quality of the included studies. RESULTS: Nineteen studies of excellent or moderate methodological quality were included. When considering all variants of the Yo-Yo test, the included studies reported intra-class correlation coefficients for test-retest reliability ranging from 0.78 to 0.98 where 62% of all intra-class correlation coefficients were higher than 0.90, while 97% of intra-class correlation coefficients were higher than 0.80. The coefficients of variation ranged from 3.7 to 19.0%. Regardless of the variant of the test, the participants' familiarization with the test, and previous sport experience, the intra-class correlation coefficients generally seem high (≥ 0.90) and coefficients of variation low (< 10%). CONCLUSIONS: The results of this review indicate that the Yo-Yo test (in all its variants) generally has good-to-excellent test-retest reliability. The evidence concerning reliability arises from 19 included studies that were of moderate or high methodological quality. Considering that most of the included studies examined the Yo-Yo intermittent recovery level 1 test while including Association Football players, more reliability studies examining Yo-Yo intermittent recovery level 2 test and Yo-Yo intermittent endurance level 1 and level 2 tests, and in the context of sports other than Association Football as well as in non-athletic populations, are required. Finally, future studies should explicitly state the type of intra-class correlation coefficient used for the reliability data analysis to allow for better between-study comparisons.

Differential Clinical Profiles, Exercise Responses, and Outcomes Associated With Existing HFpEF Definitions.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is common, yet there is currently no consensus on how to define HFpEF according to various society and clinical trial criteria. How clinical and hemodynamic profiles of patients vary across definitions is unclear. We sought to determine clinical characteristics, as well as physiologic and prognostic implications of applying various criteria to define HFpEF. METHODS: We examined consecutive patients with chronic exertional dyspnea (New York Heart Association class II to IV) and ejection fraction ≥50% referred for comprehensive cardiopulmonary exercise testing with invasive hemodynamic monitoring. We applied societal and clinical trial HFpEF definitions and compared clinical profiles, exercise responses, and cardiovascular outcomes. RESULTS: Of 461 patients (age 58±15 years, 62% women), 416 met American College of Cardiology/American Heart Association (ACC/AHA), 205 met European Society of Cardiology (ESC), and 55 met Heart Failure Society of America (HFSA) criteria for HFpEF. Clinical profiles and exercise capacity varied across definitions, with peak oxygen uptake of 16.2±5.2 (ACC/AHA), 14.1±4.2 (ESC), and 12.7±3.1 mL·kg-1·min-1 (HFSA). A total of 243 patients had hemodynamic evidence of HFpEF (abnormal rest or exercise filling pressures), of whom 222 met ACC/AHA, 161 met ESC, and 41 met HFSA criteria. Over a mean follow-up of 3.8 years, the incidence of cardiovascular outcomes ranged from 75 (ACC/AHA) to 298 events per 1000 person-years (HFSA). Application of clinical trial definitions of HFpEF similarly resulted in distinct patient classification and prognostication. CONCLUSIONS: Use of different HFpEF classifications variably enriches for future cardiovascular events, but at the expense of not including up to 85% of individuals with physiologic evidence of HFpEF. Comprehensive phenotyping of patients with suspected heart failure highlights the limitations and heterogeneity of current HFpEF definitions and may help to refine HFpEF subgrouping to test therapeutic interventions.

Correlation of the New York Heart Association classification and the cardiopulmonary exercise test: A systematic review.

AIMS: The New York Heart Association (NYHA) classification is frequently used in the management of heart failure but may be limited by patient and physician subjectivity. Cardiopulmonary exercise testing (CPET) provides a potentially more objective measurement of functional status. We aim to study the correlation between NYHA classification and peak oxygen consumption (pVO2) on Cardiopulmonary Exercise Testing (CPET) within and across published studies. METHODS AND RESULTS: A systematic literature review on all studies reporting both NYHA class and CPET data was performed, and pVO2 from CPET was correlated to reported NYHA class within and across eligible studies. 38 studies involving 2645 patients were eligible. Heterogenity was assessed by the Q statistic, which is a χ2 test and marker of systematic differences between studies. Within each NYHA class, significant heterogeneity in pVO2 was seen across studies: NYHA I (n = 17, Q = 486.7, p < 0.0001), II (n = 24, Q = 381.0, p < 0.0001), III (n = 32, Q = 761.3, p < 0.0001) and IV (n = 5, Q = 12.8, p = 0.012). Significant differences in mean pVO2 were observed between NYHA I and II (23.8 vs 17.6 mL/(kg·min), p < 0.0001) and II and III (17.6 vs 13.3 mL/(kg·min), p < 0.0001); but not between NYHA III and IV (13.3 vs 12.5 mL/(kg·min), p = 0.45). These differences remained significant after adjusting for age, gender, ejection fraction and region of study. CONCLUSION: There was a general inverse correlation between NYHA class and pVO2. However, significant heterogeneity in pVO2 exists across studies within each NYHA class. While the NYHA classification holds clinical value in heart failure management, direct comparison across studies may have its limitations.

Power of resting echocardiographic measurements to classify pulmonary hypertension patients according to European society of cardiology exercise testing risk stratification cut-offs.

BACKGROUND: Right ventricular function is the major determinant of morbidity and mortality in pulmonary arterial hypertension (PAH). The ESC risk assessment strategy for PAH is based on clinical status, exercise testing, NTproBNP, imaging and haemodynamics but does not include right ventricular function. Our aims were to test the power of resting echocardiographic measurements to classify PAH patients according to ESC exercise testing risk stratification cut-offs and to determine if the classification power of echocardiographic parameters varied in chronic thrombo-embolic pulmonary hypertension (CTEPH). METHODS: We prospectively and consecutively recruited 46 PAH patients and 42 CTEPH patients referred for cardio-pulmonary exercise testing and comprehensive transthoracic echocardiography. Exercise testing parameters analyzed were peak oxygen consumption, percentage of predicted maximal oxygen consumption and the slope of ventilation against carbon dioxide production. Receiver operator characteristic curves were used to determine the optimal diagnostic cut-off values of echocardiographic parameters for classifying the patients in intermediate or high risk category according to exercise testing. RESULTS: Measurements of right ventricular systolic function were the best for classifying in PAH (area under the curve 0.815 to 0.935). Measurements of right ventricular pressure overload (0.810 to 0.909) were optimal for classifying according to exercise testing in CTEPH. Measurements of left ventricular function were of no use in either group. CONCLUSIONS: Measurements of right ventricular systolic function can classify according to exercise testing risk stratification cut-offs in PAH. However, this is not the case in CTEPH where pressure overload, rather than right ventricular function seems to be linked to exercise performance.

Brazilian Cardiorespiratory Fitness Classification Based on Maximum Oxygen Consumption.

BACKGROUND: Cardiopulmonary exercise test (CPET) is the most complete tool available to assess functional aerobic capacity (FAC). Maximum oxygen consumption (VO2 max), an important biomarker, reflects the real FAC. OBJECTIVE: To develop a cardiorespiratory fitness (CRF) classification based on VO2 max in a Brazilian sample of healthy and physically active individuals of both sexes. METHODS: We selected 2837 CEPT from 2837 individuals aged 15 to 74 years, distributed as follows: G1 (15 to 24); G2 (25 to 34); G3 (35 to 44); G4 (45 to 54); G5 (55 to 64) and G6 (65 to 74). Good CRF was the mean VO2 max obtained for each group, generating the following subclassification: Very Low (VL): VO2 < 50% of the mean; Low (L): 50% - 80%; Fair (F): 80% - 95%; Good (G): 95% -105%; Excellent (E) > 105%. RESULTS: Men VL < 50% L 50-80% F 80-95% G 95-105% E > 105% G1 < 25.30 25.30-40.48 40.49-48.07 48.08-53.13 > 53.13 G2 < 23.70 23.70-37.92 37.93-45.03 45.04-49.77 > 49.77 G3 < 22.70 22.70-36.32 36.33-43.13 43.14-47.67 > 47.67 G4 < 20.25 20.25-32.40 32.41-38.47 38.48-42.52 > 42.52 G5 < 17.54 17.65-28.24 28.25-33.53 33.54-37.06 > 37.06 G6 < 15 15.00-24.00 24.01-28.50 28.51-31.50 > 31.50 Women G1 < 19.45 19.45-31.12 31.13-36.95 36.96-40.84 > 40.85 G2 < 19.05 19.05-30.48 30.49-36.19 36.20-40.00 > 40.01 G3 < 17.45 17.45-27.92 27.93-33.15 33.16-34.08 > 34.09 G4 < 15.55 15.55-24.88 24.89-29.54 29.55-32.65 > 32.66 G5 < 14.30 14.30-22.88 22.89-27.17 27.18-30.03 > 30.04 G6 < 12.55 12.55-20.08 20.09-23.84 23.85-26.35 > 26.36 CONCLUSIONS: This chart stratifies VO2 max measured on a treadmill in a robust Brazilian sample and can be used as an alternative for the real functional evaluation of physically and healthy individuals stratified by age and sex.

Maturational effect on Functional Movement Screen™ score in adolescent soccer players.

OBJECTIVES: The effect of maturity on Functional Movement Screen (FMS) scores in elite, adolescent soccer players was examined. DESIGN: A cross-sectional observational study was completed. METHODS: Participants were 1163 male English Football League soccer players (age 8-18 years). Players were mid-foundation phase (MF) (U9); late foundation phase (LF) (U10 and U11); early youth development phase (EYD) (U12 and U13); mid-youth development (MYD) phase (U14-U15); Late Youth Development Phase (LYD) (U16) and early professional development phase (EPD) (U18). Age from peak height velocity was estimated and players were categorized as pre- or post-peak height velocity (PHV). To analyse where differences in FMStotal score existed we separated the screen into FMSmove (3 movement tests); FMSflex (2 mobility tests) and FMSstab (2 stability tests). RESULTS: FMStotal median score ranged from 11 at MF to 14 for EPD. There was a substantial increase (10%) in those able to achieve a score of ≥14 on FMStotal in those who were post-PHV compared to pre-PHV. This was explained by a substantial increase in those achieving a score of ≥4 on FMSstab (21%). There was a substantial increase in the proportion of players who achieved the FMStotal threshold of ≥14 with an increase of 47.5 (41.4-53.6)% from the MF phase to the EPD phase due to improvements in FMSmove and FMSstab. CONCLUSIONS: PHV and maturity have substantial effects on FMS performance. FMS assessment appears to be invalid for very young players. Findings are relevant to those analyzing movement in soccer players.

Brazilian Cardiorespiratory Fitness Classification Based on Maximum Oxygen Consumption / Classificação Nacional da Aptidão Cardiorrespiratória pelo Consumo Máximo de Oxigênio

Abstract Background: Cardiopulmonary exercise test (CPET) is the most complete tool available to assess functional aerobic capacity (FAC). Maximum oxygen consumption (VO2 max), an important biomarker, reflects the real FAC. Objective: To develop a cardiorespiratory fitness (CRF) classification based on VO2 max in a Brazilian sample of healthy and physically active individuals of both sexes. Methods: We selected 2837 CEPT from 2837 individuals aged 15 to 74 years, distributed as follows: G1 (15 to 24); G2 (25 to 34); G3 (35 to 44); G4 (45 to 54); G5 (55 to 64) and G6 (65 to 74). Good CRF was the mean VO2 max obtained for each group, generating the following subclassification: Very Low (VL): VO2 < 50% of the mean; Low (L): 50% - 80%; Fair (F): 80% - 95%; Good (G): 95% -105%; Excellent (E) > 105%. Results: Men VL < 50% L 50-80% F 80-95% G 95-105% E > 105% G1 < 25.30 25.30-40.48 40.49-48.07 48.08-53.13 > 53.13 G2 < 23.70 23.70-37.92 37.93-45.03 45.04-49.77 > 49.77 G3 < 22.70 22.70-36.32 36.33-43.13 43.14-47.67 > 47.67 G4 < 20.25 20.25-32.40 32.41-38.47 38.48-42.52 > 42.52 G5 < 17.54 17.65-28.24 28.25-33.53 33.54-37.06 > 37.06 G6 < 15 15.00-24.00 24.01-28.50 28.51-31.50 > 31.50 Women G1 < 19.45 19.45-31.12 31.13-36.95 36.96-40.84 > 40.85 G2 < 19.05 19.05-30.48 30.49-36.19 36.20-40.00 > 40.01 G3 < 17.45 17.45-27.92 27.93-33.15 33.16-34.08 > 34.09 G4 < 15.55 15.55-24.88 24.89-29.54 29.55-32.65 > 32.66 G5 < 14.30 14.30-22.88 22.89-27.17 27.18-30.03 > 30.04 G6 < 12.55 12.55-20.08 20.09-23.84 23.85-26.35 > 26.36 Conclusions: This chart stratifies VO2 max measured on a treadmill in a robust Brazilian sample and can be used as an alternative for the real functional evaluation of physically and healthy individuals stratified by age and sex.

Resumo Fundamento: O teste cardiopulmonar de exercício (TCPE) é a ferramenta disponível mais completa na avaliação da capacidade aeróbica funcional (CF) do indivíduo. O consumo máximo de oxigênio (VO2 max), importante marcador biológico, reflete a real CF. Objetivo: Elaborar uma classificação de aptidão cardiorrespiratória (ACR) baseada no VO2 max em uma amostra nacional de sujeitos saudáveis e ativos de ambos os sexos. Métodos: Selecionamos 2837 TCPE de indivíduos entre 15 e 74 anos, assim distribuídos: G1 (15 a 24); G2 (25 a 34); G3 (35 a 44); G4 (45 a 54); G5 (55 a 64) e G6 (65 a 74). A ACR boa foi a média do VO2 max obtido em cada grupo, gerando as seguintes subclassificações: Muito Fraca (MF) VO2 < 50% da média; Fraca (F): 50%-80%; Regular (R): 80%-95%; Boa (B): 95%-105%; e Excelente (E) > 105%. Resultados: Homens MF < 50% F 50-80% R 80-95% B 95-105% E > 105% G1 < 25,30 25,30-40,48 40,49-48,07 48,08-53,13 > 53,13 G2 < 23,70 23,70-37,92 37,93-45,03 45,04-49,77 > 49,77 G3 < 22,70 22,70-36,32 36,33-43,13 43,14-47,67 > 47,67 G4 < 20,25 20,25-32,40 32,41-38,47 38,48-42,52 > 42,52 G5 < 17,54 17,65-28,24 28,25-33,53 33,54-37,06 > 37,06 G6 < 15 15,00-24,00 24,01-28,50 28,51-31,50 > 31,50 Mulheres G1 < 19,45 19,45-31,12 31,13-36,95 36,96-40,84 > 40,85 G2 < 19,05 19,05-30,48 30,49-36,19 36,20-40,00 > 40,01 G3 < 17,45 17,45-27,92 27,93-33,15 33,16-34,08 > 34,09 G4 < 15,55 15,55-24,88 24,89-29,54 29,55-32,65 > 32,66 G5 < 14,30 14,30-22,88 22,89-27,17 27,18-30,03 > 30,04 G6 < 12,55 12,55-20,08 20,09-23,84 23,85-26,35 > 26,36 Conclusão: A presente tabela estratifica o VO2 max aferido em esteira em uma robusta amostra nacional e pode ser utilizada como opção para a real avaliação funcional de indivíduos ativos e saudáveis de acordo com sexo e faixa etária.

Comparing Various Exercise Tests for Assessing the Response to Pulmonary Rehabilitation in Patients With COPD.

PURPOSE: Various exercise tests have been used to assess the response to pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). Few studies have compared exercise tests in the same subjects to determine the relative responsiveness of various tests. The goal of this pilot study was to examine the responsiveness of different exercise tests in patients with COPD completing PR. METHODS: Fifteen male patients with COPD underwent PR. All subjects completed 6-minute walk test (6MWT), incremental shuttle walk test (ISWT), endurance shuttle walk test (ESWT), maximal incremental exercise test (MIET), constant workload exercise test (CWET), and maximal arm ergometry tests before and after PR. The Chronic Respiratory Disease Questionnaire was also completed before and after PR. RESULTS: The number of participants who exceeded the minimal clinically important difference was similar for each of the different exercise tests. Effect sizes for the MIET and CWET were slightly higher, 0.82 and 0.97, respectively, than for the 6MWT, ISWT, and ESWT, 0.72, 0.65, and 0.60, respectively. Effect sizes were not significantly different between the 6MWT and the ESWT. The changes in exercise test results were not significantly correlated with the changes in quality of life. The improvement in laboratory cycling tests did not significantly correlate with the improvement in shuttle walk tests. CONCLUSIONS: On the basis of these data, all exercise measures were responsive to PR. Indices derived from cycling in the laboratory appeared more responsive than indices derived from walking in the field when assessed by effect size, but this finding and its possible clinical significance requires confirmation in a larger study.

Head-to-head comparison of peak upright bicycle and post-treadmill echocardiography in detecting coronary artery disease: a randomized, single-blind crossover study.

BACKGROUND: Post-treadmill digital echocardiography (post-TME) is the most widely used form of exercise echocardiography, but ischemia can rapidly resolve in the postexercise period; peak upright bicycle digital echocardiography (UBE) has the advantage of providing images at peak exercise that reflect normal physiology. However, the comparative accuracy of the two methods in detecting ischemia in the same patients is unknown. To compare the relative diagnostic value of peak UBE and post-TME in detecting coronary artery disease, both tests were performed in 86 consecutive patients undergoing coronary angiography. METHODS: Eighty-six patients referred for evaluation of coronary disease underwent peak UBE (starting at 25 W, with 25-W increments every 3 min) and post-TME (Bruce protocol) in a random sequence. Digitized images of peak UBE and post-TME were interpreted in a random and blinded fashion. RESULTS: More transient wall motion abnormalities were detected with peak UBE than post-TME (55 vs 42, P < .001), and such exercise-induced wall motion abnormalities were more extensive (5.5 ± 3.0 vs 3.4 ± 2.1 dyskinetic segments, P < .001) and more severe (regional wall motion score index, 2.7 ± 0.5 vs 2.5 ± 0.5; P = .003). By angiography, 59 patients had coronary artery disease (a coronary stenosis of ≥50% diameter narrowing); the sensitivity of peak UBE for detecting coronary artery disease was greater than that of post-TME in the population as a whole (88% vs 66%, P < .01) and in the single-vessel subgroup (72% vs 44%, P < .05), with no worsening in specificity (89% vs 89%, P = NS). CONCLUSIONS: Peak UBE is more capable of detecting ischemia than post-TME, and this is achieved with no worsening of specificity. Thus, peak UBE should be preferred in patients able to perform bicycle exercise.

Relação entre o desempenho nos testes de esforço em esteira e de seis minutos de caminhada em pacientes com claudicação intermitente dos membros inferiores / Relationship between the performance of 6 minutes walk test and treadmill test in patients with intermittent claudication of lower limbs

CONTEXTO: O teste de caminhada de seis minutos e o teste de esforço em esteira têm sido frequentemente utilizados para quantificação da limitação funcional dos pacientes com doença arterial periférica. Todavia, ainda não está bem estabelecido se os resultados desses testes são correlacionados. OBJETIVOS: Relacionar a distância total de caminhada (DTC) obtida nos testes de seis minutos e de esforço em esteira em pacientes com doença arterial periférica e sintomas de claudicação intermitente. MÉTODOS: A amostra foi composta por 34 pacientes (65,5 ± 8,9 anos) de ambos os gêneros (26 homens e 8 mulheres). Os indivíduos realizaram o teste de seis minutos em corredor de 30 metros e o teste de esforço em esteira ergométrica utilizando-se protocolo específico para essa população, com intervalo de pelo menos sete dias entre os testes. Para a análise dos dados, foi utilizada a análise de correlação de Pearson. RESULTADOS: Houve correlação significante na DTC obtida nos testes de seis minutos e de esforço em esteira (r=0,48, p<0,01). Foi observada correlação significante entre a DTC obtida nos testes nos pacientes com menor comprometimento hemodinâmico do membro (r=0,69; p=0,01), enquanto que, nos pacientes com maior comprometimento hemodinâmico do membro, a correlação não foi significante (r=0,03, p=0,91). Além disso, foi observada correlação significante entre os testes tanto nos pacientes com baixos níveis de adiposidade (r=0,57; p=0,02) como nos pacientes com altos níveis de adiposidade (r=0,48, p<0,05). CONCLUSÃO: Os resultados deste estudo mostram que os dados obtidos do teste de seis minutos e de esforço em esteira são correlacionados, exceto em pacientes com maior comprometimento hemodinâmico do membro.

BACKGROUND: Six minute walk test and treadmill test have been used to evaluate the functional limitations of peripheral artery disease patients. However, whether these tests are correlated remain poorly known. OBJECTIVE: To analyze the relationship between the total walk distance (TWD) assessed in the six minute walk test and in the treadmill test in patients with peripheral artery disease and symptoms of intermittent claudication. METHODS: Thirty-four patients (65.5 ± 8.9 yrs) of both genders (26 men 8 women) participated of the study. They performed the 6 minute walk test in a 30 meters hall and the treadmill test with a specific protocol, with an interval of at least 7 days between the tests. Pearson correlation coefficient was used for data analysis. RESULTS: Significant correlation was observed between TWD assessed in the six minute walk test and in the treadmill test. (r=0.48, p<0.01). Significant correlation between the TWD assessed in the tests were observed in the patients with lower hemodynamic limb commitment (r=0.69; p=0.01), while in the patients with higher hemodynamic limb commitment the correlation was not significant (r=0.03, p=0.91). Furthermore, a significant correlation between TWD obtained in the tests was observed in patients with low (r=0.57; p=0.02), and high levels of adiposity (r=0.48, p<0.05). CONCLUSION: The results of this study shown that walking capacity obtained with the six minute walk test and treadmill test are correlated, except in the patients with higher limb hemodynamic commitment.

Comparison study of treadmill versus arm ergometry.

The Bruce treadmill test is used worldwide to assess cardiovascular disease. However, because of the high increments of intensity between the stages of this test, it is not best suited to a number of populations. Therefore, the aim of the study was to determine the difference between physiological outcomes of the arm crank test and Bruce treadmill test and to provide a regression equation to account for this. Thirty subjects (16 men and 14 women) performed both an arm crank test and the Bruce treadmill test, on two separate days, in a random order. Peak values of oxygen uptake (VO(2) ), respiratory exchange ratio (RER), ventilation rate (V(E) ), heart rate (HR) and ratings of perceived exertion (RPE) were recorded. Arm crank VO(2peak) and peak V(E) were significantly lower compared with treadmill VO(2peak) and peak VE, in both men and women (P<0·001). Arm crank HR(peak) was significantly lower than treadmill HR(peak) in men (P<0·001). The following is the regression equation to estimate treadmill: VO(2peak) = 0·8*arm crank VO(2peak) + 0·019*body weight + 2·025*gender-0·038*gender*body weight + 0·852, with gender being '0' for males and '1' for females. This model has a r(2) of 0·832 (SEE = 0·471). This strong correlation indicates that an accurate prediction of treadmill VO(2peak) can be made by arm crank VO(2peak) , which is a good estimate of a person's maximal oxygen uptake (VO(2max) ). Therefore, the arm crank test can be of great importance for evaluation of cardiovascular disease in many people.

Sub-maximal and maximal Yo-Yo intermittent endurance test level 2: heart rate response, reproducibility and application to elite soccer.

The aims of this study were to (1) determine the reproducibility of sub-maximal and maximal versions of the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2 test), (2) assess the relationship between the Yo-Yo IE2 test and match performance and (3) quantify the sensitivity of the Yo-Yo IE2 test to detect test-retest changes and discriminate between performance for different playing standards and positions in elite soccer. Elite (n = 148) and sub-elite male (n = 14) soccer players carried out the Yo-Yo IE2 test on several occasions over consecutive seasons. Test-retest coefficient of variation (CV) in Yo-Yo IE2 test performance and heart rate after 6 min were 3.9% (n = 37) and 1.4% (n = 32), respectively. Elite male senior and youth U19 players Yo-Yo IE2 performances were better (P < 0.01) than elite youth U16s and sub-elite players (2,603 ± 451 and 2,534 ± 549 vs. 1,855 ± 535 vs. 1,749 ± 382 m). The intra- and inter-season CV for Yo-Yo IE2 test performance were 4.2 and 5.6%, respectively. A correlation was observed (P < 0.05) between Yo-Yo IE2 test performance and the total (r = 0.74) and high-intensity (r = 0.58) running distance covered in a match. A correlation was also evident (P < 0.01) between Yo-Yo IE2 test heart rate after 6 min expressed in percentage of maximal heart rate and the peak values for high-intensity running performed by midfielders in 5-min (r = -0.71), 15-min (r = -0.75) and 45-min periods (r = -0.77). The present data demonstrate that the Yo-Yo IE2 test is reproducible and can be used to determine the capacity of elite soccer players to perform intense intermittent exercise. Furthermore, the Yo-Yo IE2 test was shown to be a sensitive tool that not only relates to match performance but can also differentiate between intermittent exercise performance of players in various standards, stages of the season and playing positions.