title: Effects of the order of running and cycling of similar intensity and duration on pulmonary diffusing capacity in triathletes.
abstract: To study the pathophysiological mechanisms involved in the decrease of post-triathlon diffusing capacity (DLco), blood rheologic properties (blood viscosity: eta(b); changes in plasma volume: deltaPV) and atrial natriuretic factor (ANF) were assessed in ten triathletes during cycle-run (CR) and run-cycle (RC) trials at a metabolic intensity of 75% of maximal oxygen consumption ( VO(2max)). The DLco was measured before and 10 min after trials. ANF and deltaPV were measured at rest, after the cycle and run of CR and RC trials, and at the end of and 10 min after exercise. RC led to a greater deltaDLco decrease, a lower ANF concentration and a lower deltaPV than did CR, whereas for both CR and RC eta(b) was increased throughout exercise and 10 min after. In addition, after CR the deltaDLco decrease was inversely correlated ( r=-0.764; P<0.01) with deltaPV. The association of decreased plasma volume, increased eta(b), and lower ANF concentrations after RC suggested that lower blood pulmonary volume may have caused the greater decrease in Dlco as compared with CR. The inverse correlation between deltaPV and deltaDLco reinforces the hypothesis that fluid shifts limit the post-exercise DLco decrease after the CR succession in triathletes. Lastly, cycling in the crouched position might increase intra-thoracic pressure, decrease thorax volume due to the forearm position on the handlebars, and weaken peripheral muscular pump efficacy, all of which would limit venous return to the heart, and thus result in low pulmonary blood volume. Compared with cycling, running appeared to induce the opposite effects.
authors.affiliation: Laboratoire ACTES, Unité de Formation et de Recherche des Sciences Techniques des Activités Physiques et Sportives, Campus de Fouillole, Antilles-Guyane, 97159, Pointe à Pitre Cedex, France. galy.o@wanadoo.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Galy
authors.forename: Olivier
authors.initials: O
authors.lastname: Hue
authors.forename: Alain
authors.initials: A
authors.lastname: Boussana
authors.forename: Christelle
authors.initials: C
authors.lastname: Peyreigne
authors.forename: Isabelle
authors.initials: I
authors.lastname: Couret
authors.forename: Daniel
authors.initials: D
authors.lastname: Le Gallais
authors.forename: Jacques
authors.initials: J
authors.lastname: Mercier
authors.forename: Christian
authors.initials: C
authors.lastname: Préfaut
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D001810:Blood Volume; D002248:Carbon Monoxide / Q000378:metabolism; D005260:Female; D006325:Heart Atria / Q000737:chemistry; D006801:Humans; D008168:Lung / Q000098:blood supply; D008297:Male; D045283:Natriuretic Agents / Q000032:analysis*; D010807:Physical Endurance / Q000502:physiology*; D011187:Posture; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*; D012420:Running / Q000502:physiology*
chemical_list: D045283:Natriuretic Agents; D002248:Carbon Monoxide