Muscle coordination in cycling: effect of surface incline and posture

• Published in: Journal of applied physiology (1985) Vol. 85; no. 3; pp. 927 - 934
• Main Authors: Li, Li, Caldwell, Graham E
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-09-1998; American Physiological Society
• Subjects: Adult; Anatomy & physiology; Bicycling; Bicycling - physiology; Biological and medical sciences; Electromyography; Fundamental and applied biological sciences. Psychology; Humans; Male; Motor ability; Muscle, Skeletal - physiology; Muscular system; Posture; Posture - physiology; Space life sciences; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Human; Sport; Cyclism; Electrophysiology; Motion study; Lower limb; Electromyography; Striated muscle; Neuromuscular transmission; Ergometry; Muscular coordination; Posture
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1998.85.3.927

Biomechanics Laboratory, Department of Exercise Science,
University of Massachusetts, Amherst, Amherst, Massachusetts
01003
The purpose of the present study was to examine the
neuromuscular modifications of cyclists to changes in grade and
posture. Eight subjects were tested on a computerized ergometer under
three conditions with the same work rate (250 W): pedaling on the level while seated, 8% uphill while seated, and 8% uphill while standing (ST). High-speed video was taken in conjunction with surface
electromyography (EMG) of six lower extremity muscles. Results showed
that rectus femoris, gluteus maximus (GM), and tibialis anterior had
greater EMG magnitude in the ST condition. GM, rectus femoris, and the vastus lateralis demonstrated activity over a greater portion of the
crank cycle in the ST condition. The muscle activities of gastrocnemius
and biceps femoris did not exhibit profound differences among
conditions. Overall, the change of cycling grade alone from 0 to 8%
did not induce a significant change in neuromuscular coordination. However, the postural change from seated to ST pedaling at 8% uphill
grade was accompanied by increased and/or prolonged muscle activity of hip and knee extensors. The observed EMG activity patterns
were discussed with respect to lower extremity joint moments.
Monoarticular extensor muscles (GM, vastus lateralis) demonstrated
greater modifications in activity patterns with the change in posture
compared with their biarticular counterparts. Furthermore, muscle
coordination among antagonist pairs of mono- and biarticular muscles
was altered in the ST condition; this finding provides support for the
notion that muscles within these antagonist pairs have different
functions.
coordination; muscle activity; biarticular muscles