Limits of the dual-strategy hypothesis in an isometric plantar flexion contraction

被引:5
作者
Monohar, VJ [1 ]
Brunt, D [1 ]
Robichaud, JA [1 ]
机构
[1] Univ Florida, Dept Phys Therapy, Gainesville, FL 32610 USA
关键词
isometric contraction; trajectory; EMG; motor programing; human;
D O I
10.1007/s002210050534
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Movements have been described as being governed by a speed-sensitive (SS) or speed-insensitive (SI) strategy. The SS strategy is used when the subject controls, either explicitly or implicitly, movement speed or time. In contrast, the SI strategy is utilized when there is no intention or requirement to control movement speed. The different strategies demonstrate a specific relationship between torque trajectories and muscle activity. The purpose of this study was to determine the effect of accuracy and force level on strategy selection. Ten healthy adults were instructed to generate isometric pulse contractions of the right soleus at 20%, 40%, and 60% of maximum voluntary contraction (MVC) to reach five target sizes of percentage MVC (4%, 8%, 12%, 16%, 20%), The following results were observed: (1) there was no difference in time to peak force, peak dF/dt, slope of force, and electromyographic (EMG) measures between the 12%, 16%, and 20% target sizes; (2) differences were noted, however, between the 12%, 16%, and 20% targets and the smaller targets; (3) for the dependent measures there were significant differences between each force level. No difference between the larger targets implies that subjects do not need to implement a strategy and suggests an upper limit to the dual-strategy hypothesis. The difference between the smaller and larger targets and the difference between the force levels is indicative of an SS strategy. When asked to use different force levels, subjects controlled the rate of rise of force and regulated time to peak force. Between target sizes, force and time were modulated equally.
引用
收藏
页码:459 / 466
页数:8
相关论文
共 17 条
[1]  
CARLTON LG, 1993, VARIABILITY AND MOTOR CONTROL, P15
[2]   ORGANIZING PRINCIPLES FOR SINGLE-JOINT MOVEMENTS .2. A SPEED-SENSITIVE STRATEGY [J].
CORCOS, DM ;
GOTTLIEB, GL ;
AGARWAL, GC .
JOURNAL OF NEUROPHYSIOLOGY, 1989, 62 (02) :358-368
[3]   ORGANIZING PRINCIPLES FOR SINGLE-JOINT MOVEMENTS .4. IMPLICATIONS FOR ISOMETRIC CONTRACTIONS [J].
CORCOS, DM ;
AGARWAL, GC ;
FLAHERTY, BP ;
GOTTLIEB, GL .
JOURNAL OF NEUROPHYSIOLOGY, 1990, 64 (03) :1033-1042
[4]   INFORMATION CAPACITY OF DISCRETE MOTOR-RESPONSES [J].
FITTS, PM ;
PETERSON, JR .
JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 1964, 67 (02) :103-+
[5]   THE INFORMATION CAPACITY OF THE HUMAN MOTOR SYSTEM IN CONTROLLING THE AMPLITUDE OF MOVEMENT [J].
FITTS, PM .
JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 1954, 47 (06) :381-391
[6]  
FREUND HJ, 1978, EXP BRAIN RES, V31, P1
[7]  
GHEZ C, 1987, EXP BRAIN RES, V67, P225
[8]   TRAJECTORY CONTROL IN TARGETED FORCE IMPULSES .3. COMPENSATORY ADJUSTMENTS FOR INITIAL ERRORS [J].
GORDON, J ;
GHEZ, C .
EXPERIMENTAL BRAIN RESEARCH, 1987, 67 (02) :253-269
[9]  
GORDON J, 1984, EXP BRAIN RES, V55, P167
[10]   TRAJECTORY CONTROL IN TARGETED FORCE IMPULSES .2. PULSE-HEIGHT CONTROL [J].
GORDON, J ;
GHEZ, C .
EXPERIMENTAL BRAIN RESEARCH, 1987, 67 (02) :241-252