Variability in Energy Cost of Running at the End of a Triathlon and a Marathon

Abstract

The aim of this study was to investigate the increase in energy cost of running occurring at the end of a triathlon and a marathon event and to link them to the metabolic and hormonal changes, as well as to variations in stride length. Seven subjects took part in 3 experimental situations: a 2 h 15 min triathlon (30 min swimming, 60 min cycling and 45 min running), a 2 h 15 min marathon (MR) were the last 45 min were run at the same speed as the triathlon run (TR), and a 45 min isolated run (IR) done at triathlon speed. The results show that energy cost during MR was higher than during TR (p < 0.01) (+ 8.9%). Similar observations were made for pulmonary ventilation (+ 7.9%) and heart rate (+ 6.3%). Moreover, the values were significantly greater than the values obtained during the IR. TR and MR lead to greater weight loss (p < 0.01) (2.4 +/- 0.3 kg) than IR (1 +/- 0.2 kg). The triathlon and the marathon produced a large decrease in plasma volume (respectively 19.6 +/- 1.4% and 12.9 +/- 1.1%) compared to IR (2 +/- 0.4%). Plasma renin activity was higher for the triathlon and the marathon than for the IR (p < 0.01). MR produces a significantly greater increase in plasma free fatty acids (F.F.A.) than TR (p < 0.05) and IR (p < 0.01). In addition, the F.F.A. at the end of TR were significantly higher than IR (p < 0.05). At the end of the trial the mean stride lengths for TR and IR were greater (+ 15%) (p < 0.01) than for MR. This study, carried out with subjects running overground, confirms the decrease in running efficiency previously shown at the end of a laboratory triathlon, and demonstrates that this decrease is lower than that occurring during a marathon.

Endurance and strength training effects on physiological and muscular parameters during prolonged cycling

“…O 2 requirement of exercise (Hausswirth et al, 1996). Therefore, RER was found to decline significantly (P<0.01), which suggested that the energy source was gradually switched from carbohydrate to fat substrates during the 2-hour exercise.…”

“…An increase in energy cost with exercise duration had already been observed for prolonged exercises such as running (Davies and Thompson, 1986) or triathlon (Hausswirth et al, 1996), but relatively few data exist concerning prolonged cycling exercise. The progressive and continuous increase in V . O 2 values during the 2h task can be linked to several factors: a drift in the temperature of the subjects (Saltin and Stenberg, 1964), thermoregulation (Galloway and Maughan, 1997) and an increase in the sudoral gland activity combined with a decrease in the phosphagene way efficiency.…”

Physiological profile of elite triathletes: a comparison between young and professional competitors

“…Therefore, the cardiorespiratory response seen in these subjects cannot be explained by a movement towards fat metabolism. It should be remembered, however, that the present tests were shorter than both real competitions and the tests used in other studies Hausswirth et al, 1996); longer exercise times might be associated with an increase in the importance of this factor.…”

“…The increase in partial dehydration with core body temperature may be an important factor in the cardiorespiratory response during the cycling-running trial Hausswirth et al, 1996;Hausswirth et al, 1997;Kreider et al, 1988). In the present study all subjects were allowed 250 ml of cool water during the first 20 min of the cycling component of the C-R test, yet the HR increased significantly.…”

Efeitos da simulação de combates de muay thai na composição corporal e em indicadores gerais de manifestação de força

“…A modificação dos valores de massa corporal seguida do esforço físico tem sido amplamente estudada em modalidades cíclicas de longa duração, [16][17][18][19][20][21] …”