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2007/01/18, 03:29 PM
MUSCLE FATIGUE INCREASES METABOLIC COSTS OF ERGOMETER CYCLING WITHOUT CHANGING VO2 SLOW COMPONENT
Aivaras Ratkevicius1, Arvydas Stasiulis2, Loreta Dubininkaite2 and Albertas Skurvydas2
1School of Medical Sciences, College of Life Sciences & Medicine, Institute of Medical Sciences, Forresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK
2Department of Applied Physiology and Health Education, Lithuanian Academy of Physical Education, Sporto 6, Kaunas 3000, Lithuania
ABSTRACT
The aim of the present study was to investigate effects of muscle fatigue on oxygen costs of ergometer cycling and slow component of pulmonary oxygen uptake (VO2) kinetics. Seven young men performed 100 drop jumps (drop height of 40 cm) with 20 s of rest after each jump. After the subsequent hour of rest, they cycled at 70, 105, 140 and 175 W, which corresponded to 29.6 ± 5.4, 39.4 ± 7.0, 50.8 ± 8.4 and 65.8 ± 11.8 % of VO2peak, respectively, for 6 min at each intensity with 4-min intervals of rest in between the exercise bouts. The VO2 response to cycling after the exercise (fatigue condition) was compared to ergometer cycling without prior exercise (control condition). From 3rd to 6th min of cycling at 105, 140 and 175 W, VO2 was higher (p < 0.05-0.01) when cycling in the fatigue compared to the control condition. Slow component of VO2 kinetics was observed when cycling at 175 W in the control condition (0.17 ± 0.09, l·min-1, mean ± SD), but tended to decrease in the fatigue condition (0.13 ± 0.15 l·min-1). In summary, results of the study are in agreement with the hypothesis that muscle fatigue increases oxygen costs of cycling exercise, but does not affect significantly the slow component of pulmonary oxygen uptake (VO2) kinetics.
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2007/01/18, 03:34 PM
This study took 7 men and measured their VO2 (a measure of oxygen intake) and oxygen costs while on a cycle. Then they fatigued the subjects leg muscles through the use of depth jumps, and repeated the test.
They found that even with the same amount of output, VO2 was higher after the muscles had been fatigued. Intuitive, but concrete.
Just another reason to do weight training before cardio...
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2007/01/18, 04:34 PM
wow. I thought I understood what you were saying at first, but I am really confused. What do you mean by oxygen costs?
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Veni,Vidi,Vici.= I came, I saw, I conquered.- Ceasar
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2007/01/18, 07:07 PM
ok..im sorry..but in noob terms plz :/
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2007/01/18, 08:38 PM
Basically, after fatigueing their muscles, it required much more energy to put out the same amount of work on the machines.
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2007/01/19, 08:33 AM
Question - and this isn't for everyday training, but rather as a short change. Isn't it beneficial at time to pre-fatigue your muscles prior to working out.
For instance if you do tricep work before benching then one would think your chest would have to make up more work to account for decrease output from triceps. Or doing lunges prior to squats to pre-fatigue quads.
Not exactly the same thing, but similar. How would that study apply to a situation like this.
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2007/01/19, 12:01 PM
Depends on what you are doing. However your line of thinking is incorrect.
Pre-exhaustion is for the TARGETED muscles.
You do what you want to prioritize earlier in the workout. Just because your triceps are tired does not mean they are going to have to do significantly less work (they will still be working at their maximal output, but that output will be less). Since you end up doing more work for the triceps, your triceps will respond better than your pectorals.
I do see that kind of thinking a lot though, and it always irks me.
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2007/01/19, 06:09 PM
i got it. thanks for the article.
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Veni,Vidi,Vici.= I came, I saw, I conquered.- Ceasar
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