Am. Carter et al., Proprioceptive neuromuscular facilitation decreases muscle activity duringthe stretch reflex in selected posterior thigh muscles, J SPORT REH, 9(4), 2000, pp. 269-278
Context: Proprioceptive neuromuscular facilitation (PNF) is commonly used b
efore competition to increase range of motion. it is not known how it chang
es muscle response to rapid length changes.
Objective: To determine whether PNF alters hamstring muscle activity during
response to rapid elongation.
Design: 2 x 2 factorial.
Setting: Laboratory.
Participants: Twenty-four women; means: 167.27 cm, 58.92 kg, 21.42 y, 18.41
% body fat, 21.06 kg/m(2) BMI.
Intervention: Measurements before and after either rest or PNF were compare
d.
Main Outcome Measures: Average muscle activity immediately after a rapid an
d unexpected stretch, 3 times pretreatment and posttreatment, averaged into
2 pre-and post- measures.
Results: PNF caused decreased activity in the biceps femoris during respons
e to a sudden stretch (P = .04). No differences were found in semitendinosu
s activity (P = .35).
Conclusions: Decreased muscle activity likely results from acute desensitiz
ation of the muscle spindle, which might increase risk of muscle and tendon
injury.