European journal of applied physiology
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Eur. J. Appl. Physiol. · Nov 2002
Comparative StudyOxygen uptake and heart rate kinetics during heavy exercise: a comparison between arm cranking and leg cycling.
This study examined the oxygen uptake (VO(2)) and heart rate (HR) kinetics during arm cranking and leg cycling at work rates above the anaerobic threshold (AT). Ten untrained male subjects [21.6 (1.3) years] completed two 7 min 15 s constant-load arm cranking and two leg cycling tests at a power output halfway between the mode-specific AT and peak VO(2). ⋯ The VO(2) slow component (VO(2SC)) accounted for a significantly (P < 0.001) greater percentage of the total exercise response during arm cranking [23.8 (1.6)%] than during leg cycling [14.2 (1.5)%]. The greater relative VO(2SC) and the slower VO(2) tau with arm exercise are consistent with a greater recruitment of metabolically inefficient type II muscle fibres during arm cranking than during leg cycling.
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The paraspinal muscle responses for unexpected and expected upper limb loading were investigated by surface EMG of 20 healthy volunteers. The simultaneous trunk and hand accelerations with paraspinal, biceps brachii and soleus muscles EMG were measured in four subjects. A short-latency response of approximately 50 ms was observed in paraspinal muscles. ⋯ In conclusion, visual expectation shortens the latency and decreases the magnitude of the paraspinal muscle response to sudden upper limb loading. Also, the trial repetition has an effect on reflex latency if visual information is available. These results indicate that anticipation modulates the reflex control of paraspinal muscles, which may be significant in understanding spinal function.