Work-Energy Analysis of Triathletes Running Under Bike/Run and Run Only Conditions

  • G. Wayne Marino
  • Janice Geogan
Keywords: triathlon, run/bike

Abstract

The purpose of the study was to determine if a triathlete's running mechanics are altered at various intervals during a 10 km run or if they are affected by having just completed a 40 km bike ride. Specifically, five skilled male triathletes volunteered as subjects and were filmed at three separate intervals (l km, 5 km, and 9 km) during each of two 10 km runs. In one instance the subjects had just completed a .40 km bIcycle race while in the other condition the subjects simply ran a 10 km run following a brief warm-up. Each performance was filmed at 50 hz by a 16 mm, Locam camera and data were collected from film through use of an Altek AC 30 digitizer and microcomputer system. Raw segment end-point data were processed using a Butterworth, fourth order, low pass digital filter with a cutoff to sampling ratio of 1 to 10. Both kinematlc and work-energy data (using the method of Pierrynowskl et al., 1980) were collected for each trial and each dependent variable was evaluated for statistically significant differences using a 2 X 3 repeated measures ANOVA. The mean running velocities at each of the three intervals selected were significantly higher in the run only condltlon (6.65 m/s, 6.38 m/s, 6.83 m/s) than in the bllce/run condltion (4.28 m/s/ 4.32 m/s, 4.24 m/s). These differences were accompanied by significant changes in the length of the running stride but not in the rate of striding. Analysis of the work-energy values revealed a statistically significant interval effect for the rate of working when passive energy exchanges were accounted for. In addition, there were significant differences in the work ra te between the bike/run and run only conditions. However, no significant differences were found in either the amount of energy passively transferred or the rate of passive energy transfer in comparlsons across intervals or between condItions. It was concluded that there are significant differences in running mechanics between a run which occurs following a 40 km bike race and a run following a brief warm-up. In addition, it was concluded that significant changes in both kinematics and work-energy characteristics of running mechanics occur between various intervals in a 10 km run.