JOURNAL OF SPORTS SCIENCE & MEDICINE
ISOMETRIC GLUTEUS MEDIUS MUSCLE TORQUE AND FRONTAL PLANE PELVIC MOTION DURING RUNNING
Evie N. Burnet and Peter E. Pidcoe
Department of Physical Therapy, Virginia Commonwealth University, Richmond, VA, USA
© Journal of Sports Science and Medicine (2009) 8, 284 - 288
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|The objective of this study was to investigate the relationship
between isometric GM torque and the degree of frontal plane pelvic drop
during running. Twenty-one healthy, recreational runners (9 males, 12 females)
who ran 8.05 km or more per week were obtained from a sample of convenience.
GM maximal isometric torque was collected prior to the run. Subjects then
ran on a treadmill for 30 minutes while bilateral three-dimensional pelvic
kinematic data were collected for 10 seconds at each 2 minute increment.
Left side pelvic drop showed a slight increase (effect size = 0.61); while,
the right side pelvic drop remained stable (effect size = 0.18). Pearson's
Correlations showed no relationship between GM isometric torque and frontal
plane pelvic drop for any of the data collection periods during the 30-minute
run. These results suggest that isometric GM torque was a poor predictor
of frontal plane pelvic drop. One should question whether a dynamic rather
than static measure of GM strength would be more appropriate. Future research
is needed to identify dynamic strength measures that would better predict
biomechanical components of running gait.
Key words: Strength, kinematics, Trendelenburg, hip.
Running is becoming an increasingly popular fitness activity,
with an estimated 30 million Americans classified as recreational runners
Meanwhile, the combination of repetitive loading and the increasing number
of runners contributes to running-related injuries. In a systematic review
by van Gent et al., 2007
the overall incidence rate of lower extremity running injuries was between
19.4% and 79.3%. The majority of musculoskeletal running injuries can
be classified as overuse in nature, and can be traced to training errors,
or anatomical or biomechanical factors (Hreljac et al., 2000;
James et al., 1978;
Macera et al., 1989).
has shown that the gluteus medius muscle (GM), and to some extent the
tensor fascia, are active during the stance phase of running, corresponding
to a hip abduction moment (Mann et al., 1986).
At foot-strike, these muscles eccentrically contract to control hip adduction,
and then concentrically contract from the support phase into propulsion
to create hip abduction (Mann et al., 1986).
Because running occurs primarily in a sagittal direction, muscles associated
with the frontal and/or transverse planes could in theory become weakened
without cross training or strengthening. GM weakness, specifically, has
been linked to running-related injury (Cichanowski et al., 2007;
Fredericson et al., 2000;
Leetun et al., 2004;
Niemuth et al., 2005).
These findings suggest that strength imbalances may be associated with
or predispose an athlete to injury, or injuries may lead to strength imbalances.
subjects (9 males, 12 females) (age 25.2 ± 3.8 years, height 1.73 ± 1.0
m, weight 70.6 ± 12.3 kg, and average mileage per week 33.3 ± 18.7 km)
were recruited. The authors recognize the limitations of a mixed gender
sample; however the subjects were recruited from a sample of convenience.
In accordance with the institutional review board, research method approval
was obtained. Subjects first provided written consent and completed a
self-report running questionnaire, which included average weekly mileage
and running-related injuries in the past 6 months. Subjects were recreational
runners who ran > 8.05 km per week. Subjects were excluded if
they had a history of cardiopulmonary problems, neuromuscular impairment
preventing the subject from running safely, or physician's orders prohibiting
running. None of the subjects had an injury causing a decrement in running
performance at the time of data collection.
the average magnitude of change in pelvic angle from baseline (left and
right pelvic drop) was found for each 10-second data collection block.
average isometric GM torque was 125.67 ± 31.82 Nm and 130.09 ±
37. 96 Nm for the left and right sides, respectively. Average pelvic drop
across the 30-minute run was 10.9º ± 1.7º on the left, and 7.6º ± 1.2º
on the right. Left side pelvic drop showed a slight increase across the
run, from 9.5º ± 3.3º at minute zero to 11.9º ± 4.4º at minute 30 (effect
size = 0.61). Whereas, the right side pelvic drop remained fairly constant,
with a starting pelvic drop of 7.5º ± 2.8º and ending of 8.1º ± 3.6º (effect
size = 0.18). When comparing minute 30 means for the left and right sides,
the effect size was 0.95.
The objective of this study was to investigate the relationship between GM isometric torque and frontal plane pelvic drop in a sample of healthy, recreational runners who were instructed to run at a self-selected, comfortable pace for 30 minutes. The results indicate that GM isometric torque does not correlate well with pelvic drop in this sample. Thus, the hypothesis that pelvic drop would demonstrate an indirect relationship with isometric GM torque was not supported.
previous studies have not investigated frontal plane pelvic motion over
extended periods of running, Schache et al., 2001
did study pelvic motion over 5-second increments during treadmill running.
The 10 subjects' (9 males, 1 female) average pelvic drop was consistent
with the pelvic drop values in the current study.
|This research aimed to investigate the link between GM isometric strength and pelvic drop; however, isometric GM strength was a poor predictor of frontal plane pelvic drop. Future research studies should be aimed at investigating the relationship between dynamic measures, such as GM torque while running, clinical-based dynamic GM strength measures, GM activity and fatigue, and pelvic drop.|
|The authors wish to acknowledge J. Cortney Bradford and Emily Carney for their assistance with MatLab programming.|
Evie N. BURNET
Employment: In-Motion Physical Therapy, WIlliamsburg, USA.
This article was a portion of Dr. Burnet's doctoral dissertation from the Department of Physical Therapy, Virginia Commonwealth University, Richmond, USA.
Degree: DPT, PhD.
Research interests: Biomechanics of running, more specifically the relationship between kinematics, muscle activity, and clinical measures.
Peter E. PIDCOE
Employment: Department of Physical Therapy, Virginia Commonwealth University, Richmond, USA.
Degree: PT, DPT, PhD.
Research interests: Human performance changes with fatigue, the role of sensory information in balance recovery, and the impact of therapy on injury prevention.