I've given variations of this presentation several times as well as an article on the toic. Devil's advocate look at core training.

1. John Cissik
Human Performance Services, LLC

2. Overview
What is the core?
Hypothetical
benefits of core
training:
What we think
Why we think that
What we know
about the benefits of
core training
Future directions
“abhinc tamen caeci
caecos ducunt in
fossam simul
cadunt”(Tertullian,
Against Marcion,
Book III)
Since, however, the
blind lead the blind
they fall into the
ditch together

3. But first, mea culpa
“Abdominal training is important for
improving performance and for
preventing injuries.”
Cissik J.M. (2002). “Programming
abdominal training, part I.” Strength and
Conditioning Journal, 24(1), pg.9.

5. There is no standard definition
Author Core Muscles
Faries and Greenwood (2007) Transversus abdominus, multifidus,
obliques, quadrates lumborum,
diaphragm, pelvic floor muscles, rectus
abdominus, psoas major, erector spinae,
iliocostals, longisimus,
McGill (2010) Lumbar spine, muscles of the abdominal
wall, back extensors, quadrates lumborum,
latissimus dorsi, psoas
Oliver et al (2010) Rectus abdominis, transverse abdominis,
erector spinae, multifidus, gluteus
maximus / medius / minimus, hamstrings,
quadrates lumborum, adductor magnus,
adductor longus, adductor brevis,
pectineus, pelvic floor muscles

7. Hypothetical Benefits
Improved performance
Injury prevention
Injury treatment

8. Improved Performance:
Hypothetical
Most athletic movements originate in or
are coupled through the trunk
Maintenance of proper posture
Making muscles stronger and more
explosive

9. Coupled Through the Trunk/
I.E. Transference of Force
Example: Glide shot put
Lower body movement
Blocking
Implement Release

10. Maintenance of Posture
Back or front squats
Weakness of core muscles
Shoulders rounding forward
Missed lift, possible injury

11. Increasing Strength and Power
Increased strength and power
Improved performance in sports that
directly use the muscles (e.g. throwing
sports, tennis, etc.)

12. Injury Prevention
Lack of conditioning
Poor posture
Injury

13. What Do We Know About the Benefits of Core
Training?
Performance
Improvement
Injury Prevention
Injury Treatment
"...there is nothing
more difficult to
carry out, nor more
doubtful of success,
nor more dangerous
to handle, than to
initiate a new order
of things."
Machiavelli, The
Prince.

14. Movements Originate In or Are
Coupled Through the Trunk
Don’t movements originate in the motor cortex?
Where does this statement come from?
Panjabi, M.M. (1992). The stabilizing system of the
spine. Part I. Function, dysfunction, adaptation, and
enhancement. Journal of Spinal Disorders and
Techniques, 5(4), 383-389.
Hodges, P.W. and Richardson, C.A. (1997a).
Feedforward contraction of transversus abdominis is not
influenced by the direction of arm movement.
Experimental Brain Research, 114, 362-370.
Hodges, P.W. and Richardson, C.A. (1997b). Contraction
of the abdominal muscles associated with movement of
the lower limb. Physical Therapy, 77(2), 132-144.

15. Panjabi (1992)
From the Editor’s comment:
“…I am delighted to offer to our readership this
elegant hypothesis offered by Panjabi.”
Spinal stabilizing system:
Passive musculoskeletal subsystem: ligaments,
active at the extremes of motion only
Active musculoskeletal subsystem: muscles and
tendons
Neural and feedback subsystem: feedback and
regulation, proprioception

16. Panjabi, cont (1992)
The article is meant as an intellectual
exercise to show how the parts are
interdependent and an injury or imbalance
in one impacts the other. There are no
references attached to descriptions of the
subsystems.
A superficial reading of Panjabi seems to
suggest:
The brain plays no role in spinal stability.
The passive/active subsystems seem to be
closed loops that function outside of the motor
cortex.

17. Hodges and Richardson
(1997a)
Fine wire electrodes inserted into OE, OI,
TrA
Surface electrodes attached RA, lumbar
multifidus, and medial/posterior/anterior
deltoids.
Subjects performed 10 each unilateral
shoulder flexion, abduction, and extension
in response to a visual stimulus.
Subjects stood on a force platform that
provided feedback about unequal
distribution of subject weight.

18. Hodges and Richardson
(1997a), results
Shld Flex Shld Abd Shld Ext
TrA -32 -36 -19
OI 14 -25 -3
OE 60 8 30
RA 57 29 -9
MF 18 54 98
Chart shows time of onset of EMG activity in ms. A negative
value means activity occurred prior to deltoid activity.

19. Hodges and Richardson
(1997a), conclusions
“When the stability of the lumbar spine is
challenged by rapid motion of the upper
arm, TrA is the first trunk muscle
active… It is suggested that this muscle
may contribute to the control of trunk
stability.”

20. Hodges and Richardson
(1997b)
Similar study, looked
at hip flexion,
abduction, and
extension.
Results look at
activation relative to
activation of the hip
prime mover in ms.
Similar results.
Hip Flex Hip Abd Hip Ext
TrA -113 -70 -97
OI -75 -43 -64
OE -11 0 -32
RA -41 -27 -69
MF -67 4 -2

21. What it Says
The CNS recruits the abdominal
muscles to maintain posture during
rapid, unexpected arm and leg
movements.

22. What it Doesn’t Say
It doesn’t say movements originate in
the core.
It doesn’t say that this exists in all tasks
or all populations.
It doesn’t say that this is something that
requires special training.
It is not looking at injured, diseased, or
athletic populations.

23. Research on Core Training and
Athletic Performance
Abt et al (2007)
Childs et al (2009)
Okada et al (2011)
Sato and Mokha (2009)
Stanton et al (2004)
Tse et al (2005)
Nesser et al (2008)

24. Core Training and Performance
Study Purpose Intervention Results
Abt et al (2007) Relationship between
cycling mechanics and
core stability
Isokinetic rotation test,
32 minute core
workout, another
isokinetic test. All
followed by
incremental cycling
test.
Core workout
impacted isokinetic
core test.
No impact on pedal
force, time to
exhaustion, work, or
time on cycling test.
Greater knee and
ankle motion on
cycling test.
Childs et al (2009) Traditional sit-up
training vs. core
stabilization training
on soldiers
5 minutes/day,
4x/week either
traditional or
stabilization training.
Traditional improved
sit-up test by almost 4
sit-ups, stabilization by
almost 6.
Okada et al (2011) Relationship between
core stability,
performance, and
functional movement
screening
BOMB, t-test, single-leg
squat
Core stability (trunk
flexor, trunk extensor,
l/r lateral)
FMS: deep squat,
trunk stability push-up,
hurdle steps, inline
lunges, etc.
No relationship
between core stability
and BOMB
R .38-.44 on lateral
trunk and t-test
R .49-.5 on flexion,
lateral trunk and single
leg squat
No correlations
between core and
FMS

25. Core Training and
Performance, cont.
Study Purpose Intervention Results
Sato and Mokha
(2009)
Relationship between
core training and 5-K
running performance.
6 weeks of core
training, 4x/week
No effect on ground
reaction force or
balance.
Core group improved
5K time by 47
seconds; non-core
group by only 17
seconds.
Stanton et al (2004) Effect of Swiss ball
training on core
stability and running
economy.
25 min/day, 2x/week, 6
weeks of Swiss ball
training
Improvement in core
stability
No impact on running
economy or maximal
oxygen consumption.
Tse et al (2005) Relationship between
core training and
rowing performance
8 weeks of core
training, 2x/week
compared to not doing
core training.
No difference in sports
performance tests (VJ,
BJ, 10m shuttle, 40m
sprint, 2kg MB throw,
2000m row)

26. Abt et al (2007)
To determine the relationship between
cycling mechanics and core stability.
15 competitive cyclists
Subjects performed an incremental
cycling test; riding at 25.8 km/hour with
the elevation being increased by 1%
every 3 minutes.
Performed one week prior to
intervention.

27. Abt et al (2007), cont.
Intervention:
Isokinetic Rotation Test (pre workout):
Perform maximal intensity left and right
seated torso rotations for 3 minutes at 120
degrees/second.
Core fatigue workout:32 minute circuit of
core exercises (40 seconds on, 20 seconds
rest; 7 exercises, repeat circuit 4 times)
Isokinetic Rotation Test (post workout):
repeat, verifies core fatigue
Repeat incremental cycling test

28. Abt et al (2007), results
Core fatigue workout reduced peak torque,
total work, average power, number of
repetitions, etc. for the rotation test by 30-
43%.
No impact on pedal force, work, time to
exhaustion on the cycling test.
Greater knee and ankle motion on cycling
test.
Authors feel this is a compensatory
strategy to core fatigue.
How realistic is this situation?

29. Childs, et al. (2009).
Examined traditional sit-up training vs.
core stabilization on core performance
for soldiers.
1467 soldiers, put into two groups:
Core stabilization (CSEP)
Traditional (TEP)

30. Childs, et al. Workout
Programs.
Each exercise done for 1 minute. Each workout done
4x/week.

31. Childs, et al. Results.
The results seem straightforward, but…

32. Childs, et al.
69% of the TEP group performed sit-ups
outside of the study.
65% of CSEP performed sit-ups outside
of the study.
Did the CSEP or TEP training result in
the better sit-up score?

33. Nesser et al (2008)
Relationship between core muscle
endurance and strength/power
measurements in Division I football
players.
Variable Measure
20m Sprint (s) 2.8
40m Sprint (s) 4.9
Pro Agility (s) 4.5
Vertical Jump (in) 28.8
Clean (kg) 120.9
Back Squat (kg) 192.1
Bench Press (kg) 128.5

34. Nesser et al (2008) Results
Trunk Flexion Back Extension Right Flexion Left Flexion Total Core
20m Sprint -0.485 -0.367 -0.41 -0.376 -0.539
40m Sprint -0.479 -0.366 -0.435 -0.397 -0.604
Pro Agility -0.443 -0.346 -0.354 -0.374 -0.551
Vertical Jump 0.436 0.536 0.403 0.334 0.591
Clean 0.017 0.029 0.083 0.008 0.041
Back Squat -0.416 -0.219 -0.322 -0.294 -0.47
Bench Press -0.157 -0.234 -0.045 -0.179 -0.217
p <= 0.05
p <=0.01

35. Nesser et al (2008)
Conclusions
While statistically significant, the
correlations between core endurance and
strength/power were weak to moderate.
The tests used to measure core may not be
specific to strength and power.
Core endurance may only play a minor role in
strength and power performance.
The research doesn’t show cause and effect.
“It is the authors’ opinion that core training
is necessary for optimal sport performance
and should not be dismissed.”

36. Nesser et al (2008)
thoughts
It is possible that core endurance =
improved performance
But, it is also possible that improved
performance on all these exercises/tests
= improved core endurance

37. Research on Core Training and
Injury Prevention
Fatigue
Challenges
Evidence

38. Trunk Kinematics and
Fatigue
From Sparto, et al. (1997). The effect
of fatigue on multijoint kinematics,
coordination, and postural stability
during a repetitive lifting test. Journal of
Occupational and Sport Physical
therapy, 25(1): 3-12.

39. Sparto, et al (1997).
Lifting 25% of
maximal isoinertial
weight from mid-shank
to waist level
until subjects could no
longer continue.
By the end of the
study, subjects had
moved from a squat
style of lifting to a
stoop style of lifting –
i.e. fatigue impacted
lifting mechanics.

40. Sparto, et al (1997),
conclusions
Fatigue has an impact on lifting
mechanics.
Altered lifting mechanics could cause
lower back injuries especially in settings
of occupational lifting.
No recommendations about special
conditioning to avoid fatigue.

41. Challenges with Injury
Prevention
What injury is being prevented?
Specific lower back pain (SLBP)
Non-specific lower back pain (NSLBP)
What causes SLBP?
What causes NSLBP?

42. Causes of SLBP
Single event
vs.
Incremental, progressive
Theories, no consensus. Difficult to
study.

43. Causes of NSLBP
Bakker et al (2009) report that 100
potential risk factors for NSLBP have
been identified. In a review, they
concluded:
Conflicting Evidence: No Association:
Heavy physical work Leisure time sports/physical exercise
Leisure time activities (like gardening) Prolonged standing/walking
Whole-body vibration work Sitting at work
Bent or twisted working positions

44. Causes of NSLBP
Pransky et al (2010) report conflicting
evidence on the role of heavy physical
activity in causing NSLBP.
They report that NSLBP is increasingly
being viewed as a complex
epidemiological problem that develops
in childhood or adolescence.

45. Causes of NSLBP
Balague, et al (2010) find no relationship
between ROM, strength, and LBP in
adolescents.
They do find the following to be related
to LBP in adolescents:
Regular participation in sports
Family history
BMI

46. BMI and LBP
Heuch et al (2010) surveyed 63,000
Norwegians and found a relationship
between BMI and LBP.
BMI % with LBP
<20 14.4%
20-24.9 19.3%
25-29.9 21.4%
30-34.9 23.6%
>= 35 25.8%

47. Causes of NSLBP
Unclear
May be a relationship between BMI and
NSLBP.
With most other factors, there is
conflicting evidence and no consensus.

48. Prevention: Challenges
It’s possible that SLBP and NSLBP have
different injury mechanisms.
It’s unclear what causes either injury.
Since there’s no certainty of the cause, it’s
difficult to prevent these injuries.
If they have different injury mechanisms, then
they require different approaches to
prevention.
Exercise is frequently touted as a way to
prevent, despite the fact that it is not clear that
what it addresses causes the injuries…

49. Exercise as Prevention
Nadler et al (2002)
Followed D1 athletes, 98-99 season and 99-
00 season, NSLBP
Implemented core strengthening program
99-00 (squats, lunges, leg presses, cleans,
isolated abdominal exercises, back
extensions, etc.).
Incidents of LBP:
○ 98-99: 14/164 athletes
○ 99-00: 14/236 athletes
○ Only 81 athletes participated in both seasons

50. Nadler et al (2002), cont.
Found some relationship between hip
abductor imbalance and NSLBP in
female athletes, none in male
No relationship between strength
training and NSLBP

51. Durall, et al (2009)
15 D3 gymnasts
10 weeks of core training, 2x/week
After 10 weeks none of the gymnasts
suffered a new lower back injury
Some limitations to this study…

52. Injury Prevention
Core training to prevent injuries sounds
good.
We cannot say with certainty that this
works.

53. Research on Core Training and
Injury Treatment
Hayden, et al. (2011). Exercise therapy for
treatment of non-specific low back pain.
The Cochrane Library, 2.
www.thecochranelibrary.com/
Keller, et al. (2007). Effect sizes of non-surgical
treatments of non-specific low-back
pain. European Spine Journal, 16:
1776-1788.
Van Middelkoop, et al. (2010). Exercise
therapy for chronic nonspecific low-back
pain. Best Practice & Research Clinical
Rheumatology, 24: 193-204.

54. Hayden et al (2011)
Reviewed 61 studies looking at the
impact of exercise on NSLBP:
Population: # Studies
Healthcare 33
Occupational 12
General 7
Mixed 7
Outcome Measures:
Pain 52
Functional abilities 46
Work status 21
Global assessment 13
Type of NSLBP:
Acute (<6 weeks) 11
Sub acute (6-12
weeks) 6
Chronic (>12 weeks) 43

55. Hayden et al (2011), results
For acute pain, exercise does not result in
lower pain or greater functional outcomes.
For sub acute pain, “…there is insufficient
evidence to support or refute the
effectiveness of exercise therapy… for
reducing pain intensity and improving
function.”
For chronic pain, “There is strong evidence
that exercise therapy is at least as effective
as other conservative interventions, and
conflicting evidence that exercise therapy
is more effective…”

56. Hayden et al (2011), challenges
Apples to oranges comparisons:
Populations studied
Exercise programs
Chronic pain exercise programs were
typically performed in a healthcare
setting with individualized programs.
This is not the case with acute and sub
acute.

57. Keller et al (2007)
Compare various NSLBP treatments to
placebo or no-treatment to estimate an
effect size for each treatment.
Looked at 41 studies
Effect Sizes: Measures the magnitude of
the relationship between two
populations:
Small: .2-.5
Moderate: .5-.8
Large: >.8