Locomotion in restricted space: kinematic and electromyographic analysis of stoopwalking and crawling.
Stoopwalking and crawling are compulsory gait techniques in some occupational settings, as in low-seam coal mines (where vertical space may be less than 122 cm). Nine participants, six males and three females (mean=35 years+17 SD), participated in a study examining kinematic and electromyographic (EMG) responses to natural cadence stoopwalking, four-point crawling (all fours), and two-point crawling (knees only). EMG data were collected from knee extensors and flexors, and a motion analysis system was used to obtain kinematic data. The average gait velocity for stoopwalking was 1.01 (±0.32)m/s with an average cadence of 112.8 steps/min and stride length of 1.04 m. Four-point crawling velocity averaged 0.50 (±0.20)m/s, with average cadence of 86.3 steps/min and stride length of 0.69m. Two-point crawling exhibited the slowest velocity (0.32m/s) and shortest stride length (0.40 m); however, cadence was greater than four-point crawling (96.8 steps/min). EMG findings included prolonged contraction of both knee extensors and flexors (compared to normative data on normal walking), increased relative activity SD of the flexors (versus extensors) in two-point crawling, and decreased thigh muscle activity in four-point crawling. Interlimb coordination in four-point crawling trials indicated trot-like, no limb pairing, and near pace-like limb contact patterns. Presence or absence of kneepads had no impact on kinematic or EMG measures (p>0.05); however, subjects complained of discomfort without kneepads (especially in two-point crawling). Results of this study have implications for work performed in underground coal mines, as well as emergency or evacuation considerations.
National Institute for Occupational Safety and Health, Office of Mine Safety and Health Research, Pittsburgh, PA 15236-0070, USA. sgallagher@cdc.gov
Sean
S
Gallagher
Jonisha
J
Pollard
William L
WL
Porter
D000328:Adult; D001696:Biomechanical Phenomena; D020378:Confined Spaces; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology