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Integrated electromyogram and oxygen uptake during positive and negative work.
Author(s) -
Bigland-Ritchie B,
Woods J J
Publication year - 1976
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1976.sp011515
Subject(s) - concentric , eccentric , oxygen , work (physics) , reproducibility , vo2 max , chemistry , bicycle ergometer , work rate , mathematics , zoology , physical medicine and rehabilitation , medicine , statistics , heart rate , physics , biology , thermodynamics , geometry , organic chemistry , quantum mechanics , blood pressure
1. Integrated electromyogram (e.m.g.) from the vastus lateralis muscles, and steady‐state rates of oxygen uptake, were measured simultaneously during the performance of set rates of positive (concentric) and negative (eccentric) work at 50 rev/min on a motorized bicycle ergometer. 2. Similar experiments were also carried out at other pedalling rates and using other leg muscles. 3. The relationships between each of the variables (integrated e.m.g., oxygen consumption) and mean torque on pedals were found to be linear (r greater than 0‐98) with a remarkable degree of reproducibility in surface e.m.g. for each subject over several months. 4. The ratio of the e.m.g. slopes at 50 rev/min (positive/negative) was 1‐96 +/‐ 0‐12 while the same ratio for the oxygen uptake slopes was 6‐34 +/‐ 0‐82. The discrepancy between the ratios suggests that not only is less muscle fibre activity required to maintain the same exerted force during negative work exercise, but there is also a substantial reduction in the oxygen uptake when the fibres are stretched. This was observed for all speeds of pedalling.