CORE TRAINING: WHAT WE THINK VS.

WHAT WE KNOW

John Cissik

Human Performance Services, LLC

Overview

What is the core? Hypothetical

benefits of core training:What we thinkWhy 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

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.

WHAT IS THE CORE?

There is no standard definitionAuthor 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

Hypothetical Benefits of Core Training

Hypothetical Benefits

Improved performance Injury prevention Injury treatment

Improved Performance: Hypothetical Most athletic movements originate in or

are coupled through the trunk Maintenance of proper posture Making muscles stronger and more

explosive

Coupled Through the Trunk/ I.E. Transference of Force

Example: Glide shot put

Lower body movement

Blocking

Implement Release

Maintenance of Posture

Back or front squatsWeakness of core muscles

Shoulders rounding forward

Missed lift, possible injury

Increasing Strength and Power

Increased strength and power

Improved performance in sports that directly use the muscles (e.g. throwing sports, tennis, etc.)

Injury Prevention

Lack of conditioning

Poor posture

Injury

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.

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.

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

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.

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.

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.

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.”

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

What it Says

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

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.

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)

Core Training and PerformanceStudy Purpose Intervention ResultsAbt 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 squatCore 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 BOMBR .38-.44 on lateral trunk and t-testR .49-.5 on flexion, lateral trunk and single leg squatNo correlations between core and FMS

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 stabilityNo 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)

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.

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

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?

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)

Childs, et al. Workout Programs.

Each exercise done for 1 minute. Each workout done 4x/week.

Childs, et al. Results.

The results seem straightforward, but…

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?

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

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

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.”

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

Research on Core Training and Injury Prevention

Fatigue Challenges Evidence

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.

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.

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.

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?

Causes of SLBP

Single event

vs. Incremental, progressive Theories, no consensus. Difficult to

study.

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

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.

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 sportsFamily historyBMI

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%

Causes of NSLBP

Unclear May be a relationship between BMI and

NSLBP. With most other factors, there is

conflicting evidence and no consensus.

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…

Exercise as Prevention

Nadler et al (2002)Followed D1 athletes, 98-99 season and 99-

00 season, NSLBPImplemented 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

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

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…

Injury Prevention

Core training to prevent injuries sounds good.

We cannot say with certainty that this works.

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.

Hayden et al (2011)

Reviewed 61 studies looking at the impact of exercise on NSLBP:

Population:  # Studies Healthcare 33 Occupational 12 General 7 Mixed 7Outcome Measures:   Pain 52 Functional abilities 46 Work status 21 Global assessment 13Type of NSLBP:   Acute (<6 weeks) 11 Sub acute (6-12 weeks) 6 Chronic (>12 weeks) 43

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…”

Hayden et al (2011), challenges

Apples to oranges comparisons:Populations studiedExercise 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.

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-.5Moderate: .5-.8Large: >.8