Applied physiology of a triathlon.

Source

Human Performance Laboratory, University of Tennessee, Memphis.

Abstract

The triathlon is an endurance contest in which contestants must compete in 3 consecutive events, usually swimming, cycling and running. Success in a triathlon depends upon the ability of the triathlete to perform each of the sequential events at optimal pace without creating fatigue that will hinder performance in the next event. The successful triathlete must, therefore, have highly developed oxygen transport and utilisation systems as well as the ability to efficiently produce a high energy output for prolonged periods without creating metabolic acidosis. Accordingly, mean VO2max values for groups of triathletes during treadmill running have been reported to range from 52.4 to 72 ml/kg/min in men; 58.7 to 65.9 ml/kg/min in women. VO2max values during cycle ergometry were 3 to 6% less than treadmill running values; tethered swimming maximums 13 to 18% less. Predictable and well-known adaptations occur in the cardiovascular systems of triathletes. Structural adaptations of the heart that have been documented in triathletes include increased left ventricular cavity size or wall thickness, or both. Morphological characteristics of the triathlete's heart appear to be unrelated to success in triathlon races. Following the acute stress of triathlon competition, alterations in both systolic and diastolic function have been observed. Heart muscle fatigue is the most likely reason for these changes, since there is a rapid return to normal with rest. Like the cardiovascular system, the musculoskeletal system responds to triathlon training. Peripheral adaptations occur that lead to increased muscle respiratory capacity and to modifications in substrate utilisation. The musculoskeletal system is the site of most injuries to triathletes, and non-traumatic overuse injuries account for 80 to 85% of the musculoskeletal injuries. Maintenance of fluid and electrolyte balance is of primary importance for the triathlete both in day-to-day training and during races. Water may be an adequate replacement fluid for short distance triathlons, but some combination of carbohydrate, electrolyte and fluid replacement is necessary for longer races. Although the physiological bases for success in a triathlon are not well understood at present, the ability to maintain minimal alterations in the homeostasis of cardiovascular, haemodynamic, thermal, metabolic, and musculoskeletal functions are of obvious importance.

PMID:: 2692116; [PubMed - indexed for MEDLINE]; http://www.ncbi.nlm.nih.gov/pubmed/2692116

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Mark Allen Boulder Triathlon Camp

Preparem os passaportes, a lenda do triathlon Mark Allen, na paraíso do treinamento para esportes de resistência, Boulder, Colorado (EUA), entre os dias 15-17 de julho de 2012, organiza um camp training. São 11 vagas disponíveis.
http://www.markallenonline.com/luismaocamp.aspx

Decrease of Endurance Performance During Olympic Triathlon

G. De Vito¹, M. Bernardi¹, E. Sproviero¹, F. Figura²

Abstract

The present study was carried out in order to quantify the athlete's endurance impairment after two out of three sequential events of Olympic Triathlon (OT). Furthermore the significance of ventilatory threshold (Tvent) and peak of oxygen uptake (VO₂peak) as triathlete's performance predictors was assessed. Tvent and VO₂peak were measured in six male triathletes performing an incremental treadmill test a week before an ad hoc triathlon event. The same test was applied immediately after the first two segments of the triathlon (1.5 km swim, 32 km bike). VO₂peak and Tvent measured during the latter test were reduced compared to the first test. VO₂peak decreased from 69 to 64 ml · kg^-1 · min1' and Tvent from 58 to 51 ml · kg^-1 · min^-1 (p<0,01), respectively. VO₂peak and Tvent measured in the first test were well correlated (P<0.05) to both running and cycling times. The Tvent measured during the second test was related to the running time but with a higher significance (p < 0.01) than in the first test. The impairment in the endurance performance induced by the first two segments of OT is an important aspect to consider both in training and in race strategy. These results also provide evidence that VO₂peak and Tvent are good predictors of triathlon performance at least in cycling and running events.

Key words

Olympic triathlon - ventilatory threshold - maximal oxygen uptake - endurance

https://www.thieme-connect.com/ejournals/abstract/sportsmed/doi/10.1055/s-2007-972958

Physiological predictors of short-course triathlon performance

SLEIVERT, GORDON G.; WENGER, HOWARD A.

Abstract

The purpose of this study was to investigate if selected physiological variables were related to triathlon performance. Eighteen male and seven female triathletes competed in a short-course triathlon (1 -km swim, 30-km cycle, 9-km run) and underwent physiological testing within 14 d. VO2max and ventilatory threshold (VT) were measured on a cycle ergometer, treadmill, and tethered swim apparatus. Leg flexion and extension strength were measured on a Cybex II isokinetic dynamometer. Multiple linear regression did not improve the prediction of triathlon performance over that provided by simple correlations, Swim performance was related to relative swim VO2max in both males (r = -0.48) and females (r = -0.93) as well as the resistance pulled at swim VT (r = -0.81) and absolute leg flexion strength (r = -0.77) in females. No physiological variables were significantly related to cycling time in either gender. Running time was related to relative VO2max (r = -0.88) in females and velocity at run VT in both females (r = -0.88) and males (r = -0.73). Relative swim VO2max, (r = -0.98), velocity at run VT (r = -0.89), and absolute leg flexion strength (r = -0.80) were related to overall performance in female triathletes. The only significant predictor of overall triathlon time for males was velocity at run VT (r = -0.78). It therefore appears that in short-course triathletes physiological variables in swimming and running are important to overall performance. Differences in sample size, group variability, and level of performance between males and females may account for the reported differences in the physiological predictors of performance between genders.
(C)1993The American College of Sports Medicine

http://journals.lww.com/acsm-msse/Abstract/1993/07000/Physiological_predictors_of_short_course_triathlon.17.aspx

Periodização do treinamento

Porque não devo treinar a mesma coisa todos os dias? Porque só posso treinar 1 hora e não 5 horas?

A resposta para essa pergunta está ligada diretamente ao sistema imune e a capacidade de se adaptar do atleta as carags de estresse. Primeiro devemos entender que a maioria dos efeitos posistivos do exercício ocorre no período de recuperação das cargas de treino, que podem corresponder a uma sessão ou até várias sessões, denominadas de ciclos. O menor ciclo de treinamento é o microciclo, mas em esportes com futebol e algumas modalidades há os chamodos submicrocliclos que possibilitam a excelêcia na sequência dos jogos de uma competição.

A intensidade e o volume afetam diretamente a resposta do sistema imune. Atividade física com intensidade moderada (<60% VO2max) esta relacionado ao aumento da resposta dos mecanismos do sistema imune. Contudo, exercícios prolongados (>65% VO2max) ou o treino excessivo parecem estar relacionado a redução da resposta dos mecanismos do sistema imune.
O Exercício intenso provoca um aumento na concentração de leucócitos na circulação. Pedersen e Bruunsgaard (1995) relatam que a imunossupressão observada é evidente quando o exer. é intenso e de longa duração (60 min ou mais). Robson e col. (1982) compararam o efeito do exer. a 80% VO2máx (durante 1 hora) com um exer. a 55%VO2max (durante 3 horas) em indivíduos ativos. Verificaram, contudo, que durante e após o esforço há um aumento similar na contagem dos neutrófilos polimorfonucleares em ambas intensidades.
As alterações nas funções dos neutrófilos parecem ser dependentes da intensidade e da duração do exercício. A reposta a diferentes cargas podem refletir um estado de stress ou imunossupressão e ser um indicativo de overtraining.
Davis e col. Verificaram que o exercício extenuante de longa duração (2,5-3,5 h) pode provocar diminuição na atividade anti-viral de macrófagos alveolares e aumentar a susceptibilidade de infecções em ratos.
A sobrecarga sobre os linfócitos mostram que durante o exercício é verificado um aumento de linfócitos em cerca de 50% a 100% em relação ao valor basal. No período de recuperação, 30 minutos após o exercício, a contagem de linfócitos diminui de 30% a 50% abaixo dos níveis pré-exercício, permanecendo assim durante 3 a 6 horas. Também os exercícios intensos de longa duração induzem a apoptose de linfócitosdevido ao aumento do cortisol, que podem estar realcionados à imunosupressão. Os exercícios intensos de curta duração (>100% VO2máx) ou intensos de longa duração (=80% VO2max) > 60 min, provocam: redução da saturação da hemoglobina arterial; aumento na temperatura corporal; lesões musculares; hipoxemia e as lesões teciduais associadas. Assim, as respostas metabólicas induzem a alterações na resposta imune com libertação de citocinas pró-inflamatórias incluindo a IL-1, a IL-6 e o TNFa.

Assim, podemos afirmar que o treinamento esta relacionado a aplicação corretas das cargas de treino e o conhecimento específico de como controlar os mecanismos de estresse que induzem a adaptação.