Jui-Hung Tu

Publications (3)1.93 Total impact

• Article: Changes in running economy following downhill running.

  Trevor C Chen, Kazunori Nosaka, Jui-Hung Tu
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  ABSTRACT: In this study, we examined the time course of changes in running economy following a 30-min downhill (-15%) run at 70% peak aerobic power (VO2peak). Ten young men performed level running at 65, 75, and 85% VO2peak (5 min for each intensity) before, immediately after, and 1 - 5 days after the downhill run, at which times oxygen consumption (VO2), minute ventilation, the respiratory exchange ratio (RER), heart rate, ratings of perceived exertion (RPE), and blood lactate concentration were measured. Stride length, stride frequency, and range of motion of the ankle, knee, and hip joints during the level runs were analysed using high-speed (120-Hz) video images. Downhill running induced reductions (7 - 21%, P < 0.05) in maximal isometric strength of the knee extensors, three- to six-fold increases in plasma creatine kinase activity and myoglobin concentration, and muscle soreness for 4 days after the downhill run. Oxygen consumption increased (4 - 7%, P < 0.05) immediately to 3 days after downhill running. There were also increases (P < 0.05) in heart rate, minute ventilation, RER, RPE, blood lactate concentration, and stride frequency, as well as reductions in stride length and range of motion of the ankle and knee. The results suggest that changes in running form and compromised muscle function due to muscle damage contribute to the reduction in running economy for 3 days after downhill running.
  Journal of Sports Sciences 02/2007; 25(1):55-63. · 1.93 Impact Factor
• Article: Changes in running economy following downhill running

  Trevor C Chen, Jui-Hung Tu
  ECU Publications.
• Source

  Available from: scsepf.org

  Article: Changes IN Running Economy Following A Repeated Bout OF Downhill Running

  Trevor C Chen, Hsin-Liang Chen, Chang-Jun Wu, Ming-Ru Lin, Che-Hsiu Chen, Li-I Wang, Shi-Yi Wang, Jui-Hung Tu
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  ABSTRACT: This study investigated whether a repeated bout of downhill running would result in less damage, and thus blunted changes in physiological and biomechanical running economy (RE) parameters, compared with changes induced by the first bout. Twelve male students performed two 30-minute bouts of downhill (–15%) running (DHR1, DHR2) at 70% of maximal aerobic capacity (V · O 2max), separated by 5 days. Maximal isometric strength of the knee extensors (MVC), muscle soreness (SOR), and plasma myoglobin (Mb) concentration were measured before, and at 0.5, 24, 48, 72, 96 and 120 hours after both DHR1 and DHR2. All subjects per-formed a 5-minute bout of level running at 85% of V · O 2max before, immediately after, and at 24, 48, 72, 96 and 120 hours after DHR1 and DHR2, during which oxygen consumption (V · O 2), minute ventilation (V · E), blood lactate (LA), heart rate (HR), respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were measured. Stride length (SL), stride frequency (SF), and range of motion for the ankle (ROM-A) and knee (ROM-K) during the level runs were analyzed using high-speed (120 Hz) video images. The results of this study showed that MVC decreased (p < 0.05) after both DHR1 and DHR2, and that there was no signifi-cant difference in MVC loss between the two bouts. SOR was increased (p < 0.05) after DHR1, but was unchanged after DHR2. Mb concentration was elevated (p < 0.05) after DHR1, with no further change (p > 0.05) after DHR2. V · O 2 , V · E , RER, HR, RPE, LA, and SF were increased (p < 0.05) for 72–96 hours after DHR1, but were elevated for only 24 hours after DHR2. Similarly, SL, ROM-A and ROM-K were decreased (p < 0.05) for 72–96 hours after DHR1, but for only 24 hours after DHR2. It is concluded that DHR2 attenuated changes in markers of muscle damage, and in measures of physiological and biomechanical RE. We suggest that the attenuated changes in the physiological and biomechanical RE parameters after DHR2 may be related to the fact that less damage was caused by the second bout of exercise.