Sex-specific abdominal activation strategies during landing.
BACKGROUND
Control of the trunk segment in landing has been implicated as a contributing factor to the higher incidence of anterior cruciate ligament injuries in females than in males. Investigating the sex-specific abdominal activation strategies during landing lends insight into mechanisms contributing to control of the trunk segment.


OBJECTIVE
To examine the abdominal activation strategies used by males and females during a landing task.


METHODS
Mixed-model (between-subjects and within-subjects) design.


METHODS
Laboratory.


METHODS
Healthy, recreationally active males (n = 20, age = 23 +/- 4.8 years, height = 1.8 +/- 0.1 m, mass = 79.6 +/- 9.9 kg, body mass index = 24.8 +/- 2.7 kg/ m (2)) and females (n = 22, age = 20.8 +/- 4.8 years, height = 1.7 +/- 0.1 m, mass = 64.1 +/- 9.2 kg, body mass index = 22.9 +/- 2.6 kg/m (2)).


METHODS
Subjects performed 5 double-leg landings from a box height of 60 cm.


METHODS
Male and female activation amplitudes for the rectus abdominis (RA), external oblique (EO), and transversus abdominis and lower fibers of the internal oblique (TrA-IO) muscles during preactivation (150-millisecond interval just before landing) and after impact (150-millisecond interval immediately after ground contact).


RESULTS
Males had greater TrA-IO activation than females ( P < .05). Males preferentially activated the TrA-IO muscles relative to the RA and EO, whereas females demonstrated no significant muscle differences. Males and females also differed by phase, with males having more TrA-IO activation than females during the preactivation landing phase ( P < .05) but not during the postimpact phase. The TrA-IO was the only muscle to significantly differ by landing phase, decreasing from preactivation to postimpact ( P < .05).


CONCLUSIONS
Males used different abdominal muscle activation strategies than females in landing. The efficacy of these muscle activation strategies to control the trunk should be assessed through trunk kinematic and kinetic measures in future studies.
Kulas
Anthony S
AS
East Carolina University, Greenville, NC, USA. kulasa@ecu.edu
Schmitz
Randy J
RJ
Shultz
Sandra J
SJ
Henning
Jolene M
JM
Perrin
David H
DH