Introdução. A necessidade de melhorar a acurácia do teste de esforço determinou o desenvolvimento de escores, cuja aplicabilidade já foi amplamente reconhecida. Objetivo. Avaliação prognóstica do coronariopata estável por meio de um novo escore simplificado ao ser comparado com o escore de Hubbard. Métodos. Um novo escore foi aplicado em 372 coronariopatas bi ou triarteriais, 71,8% homens com idade média de 59,5+9,07 anos, randomizados para angioplastia, revascularização cirúrgica e tratamento clínico, com seguimento de cinco anos. O óbito cardiovascular foi o desfecho primário. O infarto do miocárdio não-fatal, e o óbito e re-intervenção formaram o desfecho combinado secundário. O escore baseou-se em uma equação previamente validada, resultante da soma de um ponto para: gênero masculino, história de infarto, angina, diabetes, uso de insulina e ainda um ponto para cada década de vida a partir dos 40 anos. Para o teste positivo foi adicionado um ponto. Resultados. Ocorreram 36 óbitos (10 no grupo angioplastia, 15 no grupo revascularização e 11 no grupo clínico), p=0,61. Observou-se 93 eventos combinados: 37 no grupo angioplastia, 23 no grupo revascularização e 33 no grupo clínico (p=0,058). Duzentos e quarenta e sete pacientes apresentaram escore clínico 5 pontos e 216 pacientes 6 pontos. O valor de corte >5 ou >6 pontos identificou maior risco, com p=0,015 e p=0,012, respectivamente. A curva de sobrevida mostrou uma incidência de óbito após a randomização diferente daquela com escore 6 pontos (p=0,07), e uma incidência de eventos combinados diferente entre pacientes com escore <6 e 6 pontos (p=0,02). Conclusão. O novo escore demonstrou consistência na avaliação prognóstica do coronariopata estável multiarterial / Introduction. The need to improve the exercise testing accuracy, lead the development of scores, which applicability were already widely recognized. Objective. Prognostic evaluation of stable coronary disease throughout a new simplified score. Methods. A new score was applied in 372 bi or triarterial coronary patients, 71,8% men mean age 59,5+9,07 years, randomized for percutaneous coronary intervention (PCI), coronary artery bypass graft surgery (CABG) and clinical treatment, with 5 years follow-up. Cardiovascular death was considered the primary outcome. Non-fatal myocardial infarction, death and re-intervention were considered the combined secondary outcome. The score was based on a previously validated equation, resulting from a sum of one point score for: male gender, infarction history, angina, diabetes, use of insulin and one point score for each decade of life after the age of 40 years. Positive exercise testing summed one additional point score. Results. There were 36 deaths (10 in the PCI group, 15 in the CABG group and 11 in the clinical group), p=0.61. There were 93 combined events: 37 in the PCI group, 23 in CABG group and 33 in the clinical group (p=0.058). Two hundred and forty-seven patients presented a clinical score 5 points and 216 patients 6 points. The cut-off point 5 or 6 identified an increased risk, p=0.015 and p=0.012, respectively. The survival curve showed a different death incidence after the randomization when the score reached 6 points or more (p=0.07), and a distinct incidence of combined events between the patients with points score <6 and 6 (p=0.02). Conclusion. The new score showed to be consistent in the prognostic evaluation of stable multivessel coronary artery disease

Contexto: Esta tese procurou estabelecer um novo método de mensuração instantânea de fadiga central e periférica durante o exercício de corpo inteiro até a capacidade aeróbica máxima em seres humanos. Até agora, a mensuração da fadiga central e periférica tem sido limitada a tarefas musculares isoladas ou a momentos específicos após o exercício, nos quais as condições fisiológicas que levaram aos sintomas limitantes do exercício já estão abrandadas. Assim, desenvolver um método que supere estas limitações permitiria demonstrar pela primeira vez as contribuições relativas da fadiga central e periférica na limitação ao exercício, no qual haja estimulação máxima dos sistemas neuromuscular e cardiovascular. Objetivo: Desenvolver e validar um método para quantificar a fadiga muscular periférica (MF, definida como a potência produzida para uma determinada estimulação muscular), fadiga de ativação (AF, definida como a atividade muscular evocável máxima), sua soma, fadiga de desempenho (PF, definida como a perda de potência isocinética voluntária máxima em comparação com a basal) durante o exercício realizado no cicloergômetro em capacidade aeróbica máxima. Além disso, esta tese teve como objetivo determinar as taxas de recuperação nas quais MF, AF e PF retornaram à linha de base após a intolerância durante o exercício de corpo inteiro em seres humanos. Métodos: Para quantificar a fadiga durante o exercício de corpo inteiro, foi desenvolvido um método para permitir uma rápida transição do ciclismo padrão (em que a relação entre potência e cadência é hiperbólica) para o ciclismo isocinético (em que a potência é independente da cadência, e a cadência é fixa). Assim, ao pedir para o participante realizar um esforço isocinético máximo em qualquer ponto durante o exercício ou na fase de recuperação, permitiu-se quantificar o declínio velocidade-específica da potência isocinética máxima (PISO). A diferença na PISO entre a linha de base e o exercício quantifica a PF. Foi testado se a relação de base entre PISO e potência eletromiográfica em 5 músculos da perna (RMS EMG) era velocidade dependente, linear e reprodutível, de tal modo que as contribuições relativas para PF pudessem ser isoladas a partir de: 1) a diminuição da ativação muscular (AF) ; e 2) o declínio na PISO num dado grau de ativação (MF). Resultados: Participantes saudáveis (n=13, 29-72 anos, variando em capacidade aeróbica de 23,5 até 62,4 ml/min/kg) completaram tiros isocinéticos esforço-variável de curta duração (5 s) a 50, 70 e 100 rpm para caracterizar a relação basal entre EMG RMS e potência isocinética. As correlações entre EMG-Piso basais foram lineares (r2= 0,95 ± 0,04) e velocidade dependente (análise de covariância). Posteriormente, testes de exercício incrementais repetidos foram realizados em uma bicicleta ergométrica e as trocas gasosas e a ventilação foram mensuradas respiração a respiração. O exercício encerrava com um esforço isocinético máximo (5 s) a 70 rpm. Na intolerância, PISO (duas pernas, 335 ± 88 W) foi ~ de 45% menos do que na linha de base (630 ± 156 W, p <0,05). Após a intolerância, houve recuperação da PISO em 3 minutos (p <0,05). AF e MF (medido em uma perna) foram de 97 ± 55 e 60 ± 50 W, respectivamente. As médias de viés (± limites de concordância) para a reprodutibilidade foram as seguintes: PISO na linha de base 1 ± 30 W; PISO na recuperação 0-min 3 ± 35 W; e EMG em PISO 3 ± 14%. Conclusões: A relação basal EMG-PISO foi bem modelada por uma função linear, que foi reprodutível no dia-a-dia. A variabilidade das mensurações EMG-PISO individuais entre ~ 25% e 100% de esforço, em torno do modelo linear, foi suficientemente forte de modo que a relação linear basal permitiu uma quantificação precisa de AF e MF no limite de tolerância e na recuperação do exercício aeróbico máximo. Foi também demonstrado que a relação EMG-PISO foi velocidade dependente, como esperado a partir da curva parabólica de potência-velocidade. Assim, esta tese apresenta um novo método útil para identificar as contribuições da fadiga central e periférica na limitação do exercício de corpo inteiro em seres humanos. / Background: This thesis sought to establish a new method for instantaneous measurement of central and peripheral fatigue during whole-body exercise up to maximal aerobic capacity in humans. Until now, measurement of central and peripheral fatigue has been limited to isolated muscle tasks or to time points after exercise where the physiological conditions that brought about the limiting symptoms for exercise have subsided. Thus, development of a method to overcome this would allow the first demonstration of the relative contributions of central and peripheral fatigue to limiting exercise that elicited maximal strain of the combined neuromuscular and cardiopulmonary systems. Objective: To develop and validate a method for quantifying peripheral muscle fatigue (MF, defined as the power produced for a given muscle stimulation), activation fatigue (AF, defined as the maximal evocable muscle activity), their sum, performance fatigue (PF, defined as the decline in maximal voluntary isokinetic power compared to the fresh, baseline, state) during cycling exercise at maximal aerobic capacity. In addition, this thesis aimed to determine the rate with which MF, AF and PF recovered to baseline after intolerance during whole-body exercise in humans. Methods: To quantify fatigue during whole-body exercise, a method was developed to allow a rapid switch from standard cycling (where the relationship between power and cadence is hyperbolic) to isokinetic cycling (where power is independent of cadence, and cadence is fixed) to be implemented. By asking the participant to give a maximal isokinetic effort at any point during exercise or recovery, allowed the velocity-specific decline in maximal isokinetic power (PISO) to be measured. The difference in PISO between baseline and exercise quantified PF. It was tested whether the baseline relationship between PISO and electromyographic power in 5 leg muscles (RMS EMG) was velocity dependent, linear and reproducible, such that the relative contributions to PF could be isolated from: 1) the decline in muscle activation (AF); and 2) the decline in PISO at a given activation (MF). Results: Healthy participants (n=13, 29 to 72 years old, ranging in aerobic capacity from 23.5 to 62.4 ml/min/kg) completed short (5 s) variable-effort isokinetic bouts at 50, 70, and 100 rpm to characterize the baseline relationship between RMS EMG and isokinetic power. Individual baseline EMG-PISO relationships were linear (r2 = 0.95 ± 0.04) and velocity dependent (analysis of covariance). Subsequently, repeated ramp incremental exercise tests were performed on a cycle ergometer and breath-by-breath gas exchange and ventilation was measured. Exercise was terminated with a maximal isokinetic effort (5 s) at 70 rpm. PISO at intolerance (two legs, 335 ± 88 W) was ~45% less than baseline (630 ± 156 W, p < 0.05). Following intolerance, PISO recovered within 3 minutes (p < 0.05). AF and MF (measured in one leg) were 97 ± 55 and 60 ± 50 W, respectively. Mean bias (± limits of agreement) for reproducibility were as follows: PISO at baseline 1 ± 30 W; PISO at 0-min recovery 3 ± 35 W; and EMG at PISO 3 ± 14%. Conclusions: The baseline EMG-PISO relationship was well modelled by a linear function, which was reproducible day-to-day. The variability of the individual EMG-PISO measurements between ~25% and 100% effort, around the linear model, was sufficiently tight that the baseline linear relationship allowed for a precise quantification of AF and MF at the limit of tolerance and in recovery from a maximal aerobic exercise task. It was also demonstrated that the EMG-PISO relationship was velocity dependent, as expected from the parabolic nature power-velocity curve. As such, this provides a valuable new method to identify the contributions of central and peripheral fatigue to limiting whole-body exercise in humans.

Objetivo: Avaliar o condicionamento cardiorrespiratório de crianças e adolescentes com BOPI através do teste cardiopulmonar de exercício (TCPE). Métodos: Foram estudadas 20 crianças com BOPI, com idade de 8 a 16 anos, que estavam em acompanhamento ambulatorial. Os pacientes realizaram TCPE máximo em esteira, teste de caminhada de seis minutos (TC6), espirometria e pletismografia, seguindo as diretrizes ATS/ACCP, ATS e ATS/ERS, respectivamente. Para o cálculo dos percentuais esperados, foram utilizados: Armstrong (TCPE); Geiger (TC6); Kundson (espirometria), Zapletal (pletismografia). Resultados: A idade média foi de 11,4 ± 2,2 anos; 70 % meninos; peso: 36,8 ± 12,3 Kg; altura: 143,8 ± 15,2 cm; IMC: 17,6 ± 3,0. Na espirometria, os pacientes apresentavam os fluxos forçados diminuídos e, na pletismografia, os volumes estavam aumentados, quando comparados com a população de referência. No TCPE, 11 pacientes apresentaram valores do VO2 de pico inferiores (77,5 ± 37,5%) a 80% do percentual do predito e o VO 2LV foi considerado normal (40%VO2). A relação VE/VVM aumentada foi observada em 68% pacientes. A média da distância total percorrida foi de 512 ± 102 m (77,0 ± 15,7%). O VO2 de pico não se correlacionou com distância (TC6); no entanto, correlacionou-se com a CVF (L) (r=0,90/p=0,00), o VEF1 (L) (r=0,86/ p=0,00) e a VR/CPT (r=-0,71/ p=0,02) e, em percentual do predito, com a VR/CPT (-0,63/ p=0,00). Conclusões: O presente estudo demonstra que os pacientes com BOPI apresentam valores do consumo de oxigênio inferiores ao da população hígida e a reserva ventilatória diminuída, sugerindo que o comprometimento pulmonar pode ser um dos fatores limitantes para o exercício. / Objective: To assess the physical conditioning of children and adolescents with Post Infectious Bronchiolitis Obliterans (PIBO) through cardiopulmonary exercise testing (CPET). Methods: 20 children with PIBO, in follow-up at an outpatient clinic carried out CPET, six minute walking test (6MWT) and pulmonary function tests (PFT), following ATS/ACCP e ATS guidelines, respectively. Results were expressed as percentage of predicted reference values: Armstrong’s for CPET, Geiger’s for 6MWT, Knudson’s for spirometry, and Zapletal’s for plethysmography.Results: Means ± SD were: for age, 11,4 ± 2,2 years; weight: 36,8 ± 12,3 kg; height: 143,8 ± 15,2 cm; BMI: 17,6 ± 3,0. Gender: 70% boys. When compared to reference values, PFT had lower forced flows (spirometry) and increased volumes (plethysmography). CPET had 11 patients with reduced VO2peak values (< 80% predicted) and had normal VO2LV (VO2peak40%). An increased VE/MVV ratio was observed in 68% of patients. The mean distance (6MWT) was 77,0 ± 15,7% of predicted (512 ± 102 m). VO2peak did not correlate with 6MWT; however, it did correlate with FVC(L) (r=0,90/p=0,00), with FEV1(L) (r=0,86/p=0,00) and with RV/TLC (r=-0,71/p=0,02). When in percentage of predicted, with RV/TLC (r=-0,63/ p=0,00). Conclusions: This study shows that PIOB patients have lower oxygen consumption values when compared to the reference population. They also showed a diminished pulmonary reserve which might have contributed to that exercise limitation.

The wheelchair tennis evidence base has developed considerably in recent years. For those with a spinal cord injury (SCI), or severe physical impairment, tennis participation represents an opportunity for skill and motor development, and potential for disease risk reduction (Abel et al., 2008). However, as a complex series of technical, tactical and physical elements are implicated, participation for novice, developmental or low-skill players can be challenging. Hence, extension of the evidence base to consider the responses of such groups during play is of considerable value. Initial experimental studies in this thesis investigated the validity, reliability and applicability of instrumentation for the assessment of wheelchair tennis court-movement. Comparisons were made between a global positioning system (GPS) and the data logger (DL) device (Study 1). GPS underestimated criterion distance in tennis-specific drills and reported lower match-play values than the DL. In contrast, DL placed on the outside wheel offered an accurate representation of distance. However, underestimations for DL were revealed at speeds > 2.50 m·s-1 during treadmill testing. Consequently, Study 2 extended this work with consideration of DL applicability for wheelchair tennis match-play. Examination of speed profiles revealed that time spent below the threshold for accuracy was trivial, confirming DL applicability for court-movement assessment. Further between-group comparisons for rank [highly-ranked (HIGH), low-ranked (LOW)], sex (male, female) and format (singles, doubles) revealed that LOW were stationary for longer than HIGH and spent more time at low propulsion speeds. Time in higher speed zones was greatest for HIGH and doubles players. Between-group differences (rank) were further scrutinised in Study 3 with attention paid to describing the physiological response of competitive match-play aligned to court-movement. Set outcome (result) was also examined. Independent of result, HIGH covered greater overall, forwards, reverse and forwards-to-reverse distances than LOW. Interestingly, HIGH winners covered greater distances than HIGH losers and had a higher mean average and minimum heart rate (HR) than LOW winners. In contrast, LOW losers had a higher mean average and mean minimum HR than LOW winners. Collectively, these outcomes suggest an enhanced ability for HIGH to respond to ball movement and the physiological and skill challenges of match-play. While this thesis confirmed that the activity duration and playing intensity is sufficient to confer health-related effects (Study 3), differences identified for rank suggested that strategies to 4 enable performance improvements in LOW were merited. The International Tennis Federation (ITF) has suggested that all starter players should be able to serve, rally and score from their first lesson (ITF, 2007). The reality however, is that chair propulsion whilst holding a racket is complex, and therefore, tennis play is challenging for novice and developmental players. Hence, the remainder of experimental work focused on interventions to enable increased court-movement and development of wheelchair tennis-specific court-mobility for LOW. The ITF have endorsed the use of a low-compression ball (LCB) for novices. An LCB bounces lower and moves more slowly through the air than a standard-compression ball (SCB). Novel findings from Study 4 revealed that greater total and forwards distances, greater average speeds and less time stationary result from use of the LCB. Increased movement activity occurred without associated increases in physiological cost, but was considered advantageous, with players adopting stronger positions for shot-play. Further examination of the linkage between movement and physiological variables were explored in the final experimental investigation (Study 5). A short period of organised practice enabled higher overall and forwards distances, and peak and average speeds to be achieved during match-play, without associated increases in physiological cost. Changes were desirable and represented enhanced court-mobility and mechanical efficiency (ME). Wheelchair tennis players were also more self-confident in tennis-specific chair-mobility, post-practice. The racket was a constraint, with lower distances and speeds, and a lower peak physiological response, achieved during tennis practice completed with a racket. This thesis advocates the use of an LCB and a short period of pre-match court-mobility practice for the novice wheelchair tennis player. Collectively, these interventions are likely to prompt greater court-movement enabling better court-positioning, develop confidence in court-mobility and shot-play, develop competence in racket handling whilst pushing, and enhancing ME. These characteristics are likely to enable participation with the likely inference being that greater competence, skill and self-confidence promotes greater enjoyment and therefore enhances longer-term compliance. This is of considerable practical significance given that tennis typically attracts new players to the game, but is less successful at retaining them (ITF, 2007).

The purpose of this thesis was to extend our understanding of the assessment and interpretation of aerobic exercise function of paediatric patients with cystic fibrosis (CF). The first investigation sought to establish (1) the validity of traditional criteria to verify maximal oxygen (V ̇O2max) during a maximal cardiopulmonary exercise test (CPET); and (2) the utility of supramaximal verification (Smax) to confirm V ̇O2max. Traditional criteria significantly underreported V ̇O2max, whilst Smax was shown to provide a valid measurement in this patient group. The reproducibility of this CPET protocol, over the short- (48 h) and medium- (4-6 weeks) term, was then established in study two. V ̇O2max was repeatedly determined with no learning effect over 48 h (typical error (TE): ∆150 mL; ∆9.3%) and 4-6 weeks (TE: ∆160 mL; ∆13.3%). Supplementary maximal and submaximal CPET parameters should be incorporated for a comprehensive evaluation of a patient, however they are characterised by greater variability over time. The influence of mild-to-moderate CF on aerobic exercise function and the matching of muscle O2 delivery-to-O2 utilisation during ramp incremental exercise to exhaustion were then examined in study three. Aerobic function was impaired in CF, indicated by very likely reduced fat-free mass normalised V ̇O2max (mean difference, ±90% CI: -7.9 mL∙kg-1∙min-1, ±6.1), very likely lower V ̇O2 gain (-1.44 mL∙min-1∙W-1, ±1.12) and a likely slower V ̇O2 mean response time (MRT) (11 s, ±13). Arterial oxygen saturation was lower in CF, supporting the notion that centrally mediated O2 delivery may be impaired during ramp incremental exercise. Although a faster rate of fractional O2 extraction would be expected in the face of reduced O2 delivery, this was not observed, suggesting additional impairment in O2 extraction and utilisation at the periphery in CF. The fourth study then demonstrated the clinical utility of CPET to assess the response to 12 weeks treatment with Ivacaftor, using a case-based design. Whilst one patient with relatively mild disease demonstrated no meaningful change in V ̇O2max, the second demonstrated a 30% improvement in V ̇O2max, due to increased O2 delivery and extraction. Furthermore, changes in aerobic function were detected earlier than spirometric indices of pulmonary function. This study demonstrated that CPET represents an important and comprehensive clinical assessment tool and its use as an outcome measure in the functional assessment of patients is encouraged. Study five investigated the V ̇O2 kinetics in this patient group. During moderate intensity cycling, the phase II V ̇O2 time constant (τ) (p = 0.84, effect size (ES) = 0.11) and overall MRT (p = 0.52, ES=0.33) were not slower in CF. However, both were slowed during very heavy intensity cycling (p = 0.02, ES = 1.28 and p = 0.01, ES = 1.40, respectively) in CF. Cardiac output and muscle deoxygenation dynamics were unaltered in CF, however, the arterial-venous O2 content difference (C(a-v ̅)O2) was reduced (p=0.03) during VH and ∆C(a-v ̅)O2 correlated with the phase II τ (r= -0.85; p=0.02) and MRT (r = -0.79; p=0.03) in CF. This study showed that impaired oxidative muscle metabolism in this group is exercise intensity-dependent and mechanistically linked to an intrinsic intramuscular impairment, which limits O2 extraction and utilisation. In conclusion, this thesis has provided guidelines for a valid and reproducible CPET protocol for children and adolescents with mild-to-moderate CF, demonstrated the utility of CPET as clinical outcome measure and furthered our understanding of the factors responsible for impaired aerobic exercise function in this patient group.

Contemporary hepatobiliary surgery practice must accurately assess operative risk in increasingly elderly populations with greater co-morbidity. Current methods fail to identify patients at high risk of postoperative complications. Cardiopulmonary exercise testing (CPET) derived anaerobic threshold (AT) and ventilatory equivalence of carbon dioxide (VE/VCO2) are validated predictors of postoperative outcome in major intra-abdominal surgery and outperform contemporary tools of risk evaluation. Despite evidence of improved in-hospital postoperative survival in large centres offering complex curative hepatobiliary surgery, morbidity remains high and long-term survival in the high-risk subset remains poor. This thesis investigated the role of validated CPET-derived markers in predicting perioperative outcomes for a high-risk hepatobiliary surgery population. It was also utilised to study the impact of malignant obstructive jaundice on peripheral oxygen extraction. In a prospective cohort of high-risk patients undergoing liver resection, an AT of 9.9 ml O2/kg/min predicted in-hospital mortality and long-term survival. Below this threshold, AT was 100% sensitive and 75.9% specific for in-hospital mortality (PPV 19%, NPV 100%). Long-term survival below the threshold of 9.9 was significantly worse when compared to those above (mortality HR 1.81). The VE/VCO2 was the most significant predictor of postoperative complications and a threshold of 34.5 provided 84% specificity and 47% sensitivity (PPV 76%, NPV 60%). Amongst the high-risk pancreaticoduodenectomy patients, VE/VCO2 was the single most predictive marker of in-hospital postoperative mortality with an AUC of 0.850 (p=0.020); a threshold value 41 was 75% sensitive and 94.6% specific (PPV 50%, NPV 98.1%). The VE/VCO2 41 was also the only predictor of poor long-term survival (HR 1.90). Notably, AT, Revised Cardiac Risk Index and Glasgow Prognostic Score did not predict outcome after pancreaticoduodenectomy. Patients with malignant obstructive jaundice, evaluated for peripheral oxygen extraction using CPET, showed lower mean peak oxygen consumption (peak VO2) at 63±17.4% of the predicted value. This was noted in absence of any significant pre-existing cardiopulmonary disease and normal respiratory reserve. Normal patterns of oxygen extraction were seen at rest, during incremental work rate and peak exercise levels. Levels of oxygen partial pressure and saturation exceeded baseline values after exercise signifying normal microcirculatory responses. Thus, aerobic capacity was limited by dysfunction in delivery (cardiac output) rather than oxygen extraction. CPET provides useful prognostic adjuncts for early and long-term outcomes in the high-risk patients undergoing major hepatobiliary surgery. These findings provide useful tools for perioperative optimisation of the high-risk patient and plan appropriate level of postoperative care to address mortality and morbidity after surgery.

Maximal oxygen uptake (VO2max) is the internationally recognized measure of a person's cardiorespiratory fitness. Currently the most accurate way of assessing one's true VO2max involves the use of maximal exercise tests, which require the use of specialized equipment, and are time consuming and costly. The purpose of this study was to determine the validity of the submaximal Siconolfi step test to estimate VO2max. A second purpose was to determine if body fat percentage improved the validity. Thirty-six individuals underwent a maximal treadmill test, in which VO2max was directly measured, and the step test. Results indicate that, although VO2max estimates generated by the Siconolfi step test are highly correlated to true VO2max (r =.887; p<.01), the values consistently underestimated a person's aerobic fitness. It was also determined that body fat percentage did not contribute to the prediction of VO2max.

The purpose of this study was to develop a regression equation to predict VO2max based on non-exercise (N-EX) data. All participants (N = 100), aged 18-65 years old, successfully completed a maximal graded exercise test (GXT) to assess VO2max (mean ± SD; 39.96 mL∙kg-¹∙min&sup-1; ± 9.54 mL∙kg-¹∙min-¹). The N-EX data collected just before the maximal GXT included the participant's age, gender, body mass index (BMI), perceived functional ability (PFA) to walk, jog, or run given distances, and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL∙kg-¹∙min-¹, %SEE = 8.62): VO2max (mL∙kg-¹∙min-¹) = 48.0730 + (6.1779 x gender) - (0.2463 x age) - (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (Rp = .91 and SEEp = 3.63 mL∙kg-¹∙min-¹); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (aged 18-65) with a similar cardiorespiratory fitness level. Based on standardized β-weights the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women.

No description available.

published_or_final_version / Sports Science / Master / Master of Science in Sports Science