A comparison of gas exchange indices used to detect the anaerobic threshold

Caiozzo, Vincent J.; Davis, James A.; Ellis, J. F.; Azus, J. L.; Vandagriff, R.; Prietto, Carlos A.; McMaster, William C.

doi:10.1152/jappl.1982.53.5.1184

Cited by 416 publications

(234 citation statements)

References 17 publications

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“…O LV foi determinado através da combinação do método do equivalente ventilatório. 25 O consumo máximo de oxigênio (VO 2máx ) foi representando por três unidades: 1) valores absolutos (l.min -1 ), representando por VO 2máx l.(min) -1 ; 2) relativo a massa corporal (ml.kg.min -1 ), representado por VO 2máx ml. (kg.min) -1 ; 3) relativo a massa livre de gordura (ml.Kg.MLG.min -1 ), representado por VO 2máx ml.(kg.…”

Section: Avaliação Da Aptidão Cardiorrespiratóriaunclassified

Adiponectinemia e indicadores fisiológicos em adolescentes obesos asmáticos e não-asmáticos

Cieslak

Filho

Titski

et al. 2013

Medicina (Ribeirão Preto)

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RESUMOIntrodução: Considerada um problema de saúde pública, a obesidade tem sido referida como fator de risco para o desenvolvimento da asma. Assim, o excesso de peso apresenta influencia sobre a função da musculatura lisa e induz a inflamação sistêmica das vias aéreas por intermédio das adipocitocinas. Embora a adiponectina seja considerada uma citocina de caráter anti-inflamatório, uma vez que, suas concentrações decrescem na obesidade. A literatura tem demonstrado mínimas evidências do comportamento dessa adipocitocina perante os fatores envolvidos na relação de obesidade e asma. Desse modo, o presente estudo visou analisar o comportamento das respostas de adiponectinemia e parâ-metros fisiológicos em adolescentes obesos asmáticos e não-asmáticos. Métodos: Participaram 15 adolescentes obesos (seis asmáticos e nove não-asmáticos), submetidos a avaliação antropométrica, cardiorrespiratória, espirométrica e laboratorial. O diagnóstico de asma foi através de histórico clínico e questionário ISAAC, e a obesidade pelo IMC acima do percentil 95 th . Utilizou-se o teste de broncoprovocação com exercício físico para avaliação do broncoespasmo induzido pelo exercício (BIE). Resultados: Verificou-se diferença do % Queda VEF 1 (p=0,034) entre os obesos asmáticos e não-asmáticos. Para o obesos asmáticos, o coeficiente de determinação (R 2 ) demonstrou efeito da adiponectina com a PAS (r=-0,512;R 2 =0,105); HDL (r=+0,659;R 2 =0,292), glicemia (r=-0,599;R 2 =0,199), glicemia120 (r=-0,686;R 2 =0,338), insulina120 (r=-0,614;R 2 =0,221), VO 2máx Absoluto (r=+0,518;R 2 =0,086), VO 2máx Relativo MLG (r=+0,585;R 2 =0,178) e %VEF 1 (r=+0,580;R 2 =0,171). Nos obesos não-asmáticos houve efeitos da adiponectina com a insulina (r=-0,731;R 2 =0,525), HOMA-IR (r=-0,684;R 2 =0,469), QUICKI (r=+0,683;R 2 =0,535) e VO 2máx Relativo MLG (r=+0,654;R 2 =0,346). Conclusão: Verificaram-se prováveis efeitos das respostas de adiponectinemia com os parâmetros fisiológicos associados ao excesso de peso e o baixo nível de aptidão cardiorrespiratória em obesos asmáticos e não-asmáticos. Além disso, para os obesos asmáticos a adiponectinemia demonstrou um possível efeito de relação com o %VEF 1 .Palavras-chave: Adiponectina. Asma. Obesidade.

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Section: Avaliação Da Aptidão Cardiorrespiratóriaunclassified

Adiponectinemia e indicadores fisiológicos em adolescentes obesos asmáticos e não-asmáticos

Cieslak

Filho

Titski

et al. 2013

Medicina (Ribeirão Preto)

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“…24 System resistance was o2 cm H 2 O per l/s through 6 l/s for expiration. Ventilatory threshold (VTh) was determined from the comparison of gas exchange indices 25 and the V-slope method. 26 Breathing mechanics Expiratory and inspiratory flow were measured at rest and continuously during exercise as described previously.…”

Section: Gas Exchange Measurementsmentioning

confidence: 99%

Mild-to-moderate obesity: implications for respiratory mechanics at rest and during exercise in young men

2005

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OBJECTIVE:To investigate the effect of mild-to-moderate obesity on respiratory mechanics at rest and during exercise in obese men. We hypothesized that the simple mass loading of obesity would alter both end-expiratory lung volume (EELV) and respiratory pressures (gastric, P ga and transpulmonary, P TP ) in resting body positions and during graded cycle ergometry to exhaustion. SUBJECTS: A total of 10 obese (3875% body fat; mean7s.d.) and nine lean (1874%) men were studied. METHODS: Body composition (by body circumferences and hydrostatic weighing) and pulmonary function were measured at rest. Breathing mechanics were measured at rest in the upright-seated position, supine, and during cycling exercise. Data were analyzed by independent t-test. RESULTS: EELV was significantly lower in the obese men in the supine (3074 vs 3776% total lung capacity (TLC)) and seated (3976 vs 4775%TLC) positions and at ventilatory threshold (3575 vs 4577%TLC) (Po0.01). In contrast, at peak exercise, EELV was not different between groups. Respiratory pressures (P ga and P TP ) were elevated (Po0.05) during one or more phases of the breathing cycle at rest and during exercise in obese men.CONCLUSION: These data demonstrate that mild-to-moderate obesity in young men results in reduced lung volumes and alterations in respiratory mechanics when supine, seated at rest, and during exercise. During moderate exercise, obesity does not appear to limit changes in EELV; however, the regulation of EELV during heavy exercise appears to be affected.

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“…Other indirect methods to estimate such thresholds use pulmonary gas exchange data (40, 49) (i.e., ventilatory threshold) or electromyographic signals (40). Several studies have aimed to compare different methods to determine the lactate and ventilatory thresholds using different protocols (9,11,35,40), although it is difficult to draw conclusions, as the results heavily depend on the specific methodologies used (e.g., cycle or treadmill, duration of exercise stage, blood sampling site). Others have attempted to investigate the relationship between lactate or ventilatory threshold and exercise performance in thermoneutral conditions (6,19,50).…”

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confidence: 99%

Lactate threshold predicting time-trial performance: impact of heat and acclimation

Lorenzo

Minson

Babb

et al. 2011

Journal of Applied Physiology

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Lorenzo S, Minson CT, Babb TG, Halliwill JR. Lactate threshold predicting time-trial performance: impact of heat and acclimation. J Appl Physiol 111: 221-227, 2011. First published April 28, 2011 doi:10.1152/japplphysiol.00334.2011The relationship between exercise performance and lactate and ventilatory thresholds under two distinct environmental conditions is unknown. We examined the relationships between six lactate threshold methods (blood-and ventilation-based) and exercise performance in cyclists in hot and cool environments. Twelve cyclists performed a lactate threshold test, a maximal O2 uptake (V O2max) test, and a 1-h time trial in hot (38°C) and cool (13°C) conditions, before and after heat acclimation. Eight control subjects completed the same tests before and after 10 days of identical exercise in a cool environment. The highest correlations were observed with the blood-based lactate indexes; however, even the indirect ventilation-based indexes were well correlated with mean power during the time trial. Averaged bias was 15.4 Ϯ 3.6 W higher for the ventilation-than the blood-based measures (P Ͻ 0.05). The bias of blood-based measures in the hot condition was increased: the time trial was overestimated by 37.7 Ϯ 3.6 W compared with only 24.1 Ϯ 3.2 W in the cool condition (P Ͻ 0.05). Acclimation had no effect on the bias of the blood-based indexes (P ϭ 0.51) but exacerbated the overestimation by some ventilation-based indexes by an additional 34.5 Ϯ 14.1 W (P Ͻ 0.05). Blood-based methods to determine lactate threshold show less bias and smaller variance than ventilation-based methods when predicting time-trial performance in cool environments. Of the blood-based methods, the inflection point between steady-state lactate and rising lactate (INFL) was the best method to predict time-trial performance. Lastly, in the hot condition, ventilation-based predictions are less accurate after heat acclimation, while blood-based predictions remain valid in both environments after heat acclimation. heat stress; heat acclimation; heat acclimatization; critical power; endurance exercise SEVERAL PHYSIOLOGICAL PARAMETERS, namely, maximal O 2 uptake (V O 2max ), lactate threshold, ventilatory threshold, fraction of slow-twitch fibers, and running economy, are known to be related to (or predictive of) endurance exercise performance (12,13,19). As the margins for success in athletic competition are often quite small, coaches, athletes, and physiologists have long been interested in assessing an individual athlete's lactate or ventilatory threshold, in an effort to use such information to design more effective training plans, optimize an athlete's performance, or make race-day predictions. The terms "lactate threshold" and "ventilatory threshold" have generally been used to define the highest work rate or O 2 uptake (V O 2 ) at which athletes can maintain their efforts over a specified time frame. To the best of our knowledge, no study has focused on simultaneously determining the accuracy of lactate threshold vs. ventila...

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A comparison of gas exchange indices used to detect the anaerobic threshold

Cited by 416 publications

References 17 publications

Adiponectinemia e indicadores fisiológicos em adolescentes obesos asmáticos e não-asmáticos

Adiponectinemia e indicadores fisiológicos em adolescentes obesos asmáticos e não-asmáticos

Mild-to-moderate obesity: implications for respiratory mechanics at rest and during exercise in young men

Lactate threshold predicting time-trial performance: impact of heat and acclimation

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