The traction reaction was studied in 23 normal infants on 45 occasions at ages ranging
from 2 weeks to 12 months. The distribution of the developmental phases of the reaction
to some extent differed from that expected from age according to the description of
Vojta (1976). EMG recordings from 15 trunk and leg muscles were obtained on 37 occasions
from 20 of the infants. Six types of EMG activation pattern during traction were observed
in different overlapping age periods from 1 month to 12 months. From these patterns,
four well separated stages of motor development were distinguished. They were as follows:
1) No EMG activity related to traction.
2) Trunk flexor activation with weak or irregular activation in leg muscles.
3) Reciprocal activation in trunk flexor and extensor muscles combined with strong
co-activation of the leg muscles, and
4) Trunk muscles activated as in stage 3, but the coactivation in leg muscles abolished
and gradually followed by functionally adequate activation in some of the leg muscles.
Traction reaction - Development phases - Normal infants - Electromyography
