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Musculoskeletal Health in Women: Impact of Stress, Aging,
and PregnancyRita Deering, DPT, PhD candidate
Clinical & Translational Rehabilitation Health Sciences PhD Program
Department of Physical Therapy
Marquette University
Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
History
• Women have historically been excluded from clinical research due to “greater biological complexity”
• Many health care findings from research conducted on men have been generalized to be applicable to women
• 1990: NIH established a policy stating that women should “commonly” be part of medical and behavioral research
• 2012: The journal Endocrinology mandated that methods sections must disclose the sex of subjects studied (whether human, animal or cell cultures) (Blaustein Endocrinology, June 2012, 153(6):2539–2540)
• 2015: NIH issued the announcement “Consideration of Sex as a Biological Variable in NIH-funded Research”
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“Sex” vs. “Gender”
• Sex: biological differences (reproductive organs, chromosomes)
• Gender: a “complex psychological, environmental, sociocultural,
and political framework that encompasses the characteristics ascribed to each sex that are generally accepted and influenced by society.” (M. Racine et al 2012)
www.thewrap.comwww.museumofplay.org
Skeletal Muscle Strength
Force
• Voluntary activation: ability of the
nervous system to drive the muscle
• Muscle cross-sectional area: number
of muscle fibers and sarcomeres in
parallel
Maximal strength
Slide courtesy of Dr. Sandra Hunter, PhD
Muscle Strength and Fatigue
An acute, exercise-induced reduction in the force or
power of a muscle (Gandevia, 2001; Enoka and Duchateau 2008).
Force
100 %
Before After
Fatiguing
Exercise
Decline
Maximal
Force
Slide courtesy of Dr. Sandra Hunter, PhD
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Muscle Function: Muscle Function: Muscle Function: Muscle Function: Strength, Fatigability and Steadiness
-5.0
3
2
1
0
volt
V-F
orc
e
1
20 30 40 50 60 70 80 90100110120130140150160170180190200210220230240250260270280290300310320330340350360
s60 s
50% MVC
force
Time to Task Failure
Maximal strength
• Strength
• Muscle Fatigue: reduction in strength and time to task
failure
• Steadiness: force fluctuationsSlide courtesy of Dr. Sandra Hunter, PhD
Subje
ct
Num
bers
0
500
1000
1500
2000
2500
3000
Men Women
Muscle Fatigue Studies
78 studies (as of
April 2014)
Disproportionate testing of men compared with women or the
under-reporting of sex effects can mask an understanding of
relevant sex differences in fatigability and performance.
Sex Differences in Research of Muscle Function and Fatigability
Slide courtesy of Dr. Sandra Hunter, PhD
Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
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Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
Sex Differences in Skeletal Muscle Function
www.si.com
Muscle Mass & Strength
• Men have more muscle mass than women, thus are usually stronger
• When strength is normalized to muscle mass, the sex difference in strength is negligible
• Greater muscle mass and higher force levels are usually associated with greater fatigability during sustained isometric contractions
• Greater compressive force generated by larger muscle mass can impair muscle perfusion and clearance of metabolic byproducts
Hunter SK Acta Physiologica 2014
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Force (% Max)
10 20 30 40 50 60 70 80 90 100
Se
x D
iffe
rence
in F
atigue (
%)
-40
-20
0
20
40
60
80
Adductor Pollicis
Finger Flexors
Elbow Flexors
Elbow Extensors
Neck Muscles
Back Extensors
Knee Extensors
Ankle Dorsiflexors
Women more fatigue resistant than men
>55 studies
Static Contractions
Hunter SK Acta Physiologica 2014
Sex Differences in Fatigability Sex Differences in Fatigability Sex Differences in Fatigability Sex Differences in Fatigability
Slide courtesy of Dr. Sandra Hunter, PhD
Time to Task Failure
Men: 819 + 306 s
Women: 864 + 391 s
P>0.05
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Trunk Flexor MVC StrengthUpright Sitting
Women Men
MV
C T
orq
ue
(N
m)
0
10
20
30
40
50
60
70
Trunk Flexor FatigabilityIntermittent Isometric Submaximal Fatiguing Protocol
Women Men
Tim
e to
Ta
sk F
ailu
re (
s)
0
200
400
600
800
1000
Association Between Trunk Flexor Strength and Trunk Flexor Fatigability
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400 1600 1800
MV
C S
treng
th (
Nm
)
20
40
60
80
100
120 Women
Men
Impact of Stress on Fatigability
Keller-Ross et al 2014
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Impact of Stress on Control of Force
Pereira et al 2015
Sex Differences in Muscular Response to Unloading
• Women have greater loss of total volume of muscle and fiber area, especially for type II fibers.
• For 30 days of unloading, women demonstrate more significant decline in strength as compared to men.
• With short term unloading, women show more dysfunction in neural activation.
• Women may require greater recovery time than men following unloading.
Ploutz-Snyder et al 2014
Summary of Sex Differences
• Women are often weaker and less fatigable
• Results are task- and muscle-dependent!
• Women show greater decline in time to task failure with cognitive stress
• Women demonstrate greater deterioration of control of force with cognitive stress
• Women are more susceptible to disuse impairments (atrophy, neural activation deficits) and require greater recovery time
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Possible Mechanisms forSex Differences
Hunter SK Acta Physiologica 2014
Contractile Properties
• Women have slower muscle
• Women tend to have more Type I muscle fibers than men
• Women have slower SR Ca2+ kinetics
• ATPase activity
• Uptake into SR
Hunter SK Acta Physiologica 2014
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Muscle Metabolism
• High force isometric contractions: men demo greater glycolysis
• High intensity sprint exercise: women have lower accumulation of lactate, greater preservation of ATP
• Moderate/high intensity exercise (whole body): women oxidize more fat and less CHO
• Muscle liproprotein lipase, membrane fatty acid transport protein-1, FAT/CD36 protein, and citrate synthase levels are higher in women
• Not dependent on level of training or age
• Capacity for fat metabolism is associated with estrogen
Hunter SK Acta Physiologica 2014
Sex Hormones
• Conflicting evidence regarding influence of menstrual cycle on skeletal muscle performance
• Strength and fatigability of isometric contractions do not appear to be altered by day of menstrual cycle
• Birth control/menstrual cycle can impact metabolism, to a small degree, during long duration exercise
• Impact is more profound when climate is hot/humid
Hunter SK Acta Physiologica 2014
CNS Function
• Women demonstrate higher activation of the cortex (IL & B) during finger tapping or when preparing to reach, while men demonstrate higher activity in subcortical areas (ex: basal ganglia)
Hunter SK Acta Physiologica 2014
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Aging
“Normal” Aging• Loss of muscle mass
• Selective atrophy of Type II fibers
• Loss of alpha motor neurons
• Collateral sprouting
• Instability of neuromuscular junction
• Infiltrated by fat and fibrotic tissue
• More susceptible to negative effects of inflammation (Gheller et al 2016)
• Greater variability in motor performance
• Decreased strength and power
• Altered fatigability
• <75 years old typically LESS fatigable for isometric contractions
• >75 years old typically MORE fatigable for isometric contractions
• Old and very old MORE fatigable with high velocity dynamic contractionsHunter, Pereira, Keenan 2016
Ke
nt-B
rau
n &
Ng
19
99
Hunter, Pereira, Keenan 2016
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Sex Differences with Age• Women lose skeletal muscle mass at a slower rate than men (Gheller et al 2016)
• Women have 2.5x more fatty infiltrate in quads (Forsberg et al 1991)
• Women have lesser loss of strength than men (~50%) (Gheller et al 2016)
• Likely due to men having greater strength than women
• Old women have less loss of strength during eccentric muscle activations than old men.
• Function of “slower cross-bridge kinetics, an increased proportion of weakly-bound compared with strongly-bound cross-bridges, and a stiffer musculotendinous complex” (Hunter, Pereira, Keenan 2016)
• Old women demonstrate greater fatigability with both low and high cognitive demand (Pereira 2015)
• Mechanisms not fully understood at this time
Pereira 2015
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Discussion
• Why is fatigability important?
• Why are sex differences important?
• Clinical implications of impact of stress on performance?
• Clinical implications of impact of aging on performance?
• Other clinical insights from the group?
www.hulu.com
References• Blaustein JD. Animals Have a Sex, and so Should Titles and Methods Sections of Articles in Endocrinology. Endocrinology 2012; June, 153(6): 2539-2540.
• Racine et al. A Systematic Literature Review of 10 Years of Research on Sex/Gender and Experimental Pain Perception: Parts 1 & 2. Pain 2012. 153: 602-618, 619-635.
• Hunter SK. Sex differences in human fatigability: mechanisms and insight to physiological responses. Acta Physiologica 2014; 210: 768-789.
• Hunter et al. Fatigability of the elbow flexor muscles for a sustained submaximal contraction is similar in men and women matched for strength. J ApplPhysiol 2004; 96: 195-202.
• Hunter et al. Men are more fatigable than strength-matched women when performing intermittent submaximal contractions. J Appl Physiol 2004; 96: 2125-2132
• Keller-Ross et al. Stressor-induced increase in muscle fatigability of young men and women is predicted by strength but not voluntary activation. J ApplPhysiol 2014; 116: 767-778.
• Pereira et al. Age and sex differences in steadiness of elbow flexor muscles with imposed cognitive demand. Eur J Appl Physiol 2015; 115(6): 1367-1379.
• Ploutz-Snyder et al. Effects of sex and gender on adaptation to space: musculoskeletal health. J Womens Health 2014; 23(11): 963-6.
• Hunter SK, Pereira HM, Keenan KG. The Aging Neuromuscular System and Motor Performance. J Appl Physiol 2016; August; doi: 10.1152/japplphsiol.00475.2016 [epub ahead of print]
• Kent-Braun JA & Ng AV. Specific strength and voluntary muscle activation in young and elderly women and men. J Appl Physiol 1999; 87(1): 22-9.
• Gheller et al. Understanding Age-related changes in skeletal muscle metabolism: Differences between males and females. Annu Rev Nutr 2016; 36: 129-56.
• Forsberg et al. Muscle composition in relation to age and sex. Clin Sci 1991; 81: 249-56.
• Pereira et al. Sex differences in arm muscle fatigability with cognitive demand in older adults. Clin Orthop Relat Res 2015; 473: 2568-2577.
Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
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Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
Pregnancy & Postpartum
http://www.xsight.com.au
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Presentation Overview
• History & Definitions
• Sex Differences in Muscle Function• Impact of stress on sex differences
• Impact of Aging on sex differences
• Discussion of Clinical Importance
• Pregnancy & Postpartum• Physiological Changes
• Common PT related issues
• Clinical Assessment of pregnancy related PGP
• Abdominal Muscle Function & Pain Perception after Pregnancy
• Discussion of Clinical Importance
Hormonal Changes
• Estrogens
• Levels increase
• Estradiol, estrone, estriol
• Facilitate growth of the uterine muscle
• Cause the ligaments of the pelvis and the pubic symphysis to become softer and more lax
• Contribute to growth of milk ducts
• Boost release of prolactin from mother’s pituitary gland
• Increases creation of progesterone
Chearskul 2006
Hormonal Changes
• Progesterone
• Increases
• Necessary for implantation and successful maintenance of pregnancy
• Maintains lining of the uterus and facilitates production of nutrients to sustain zygote early in pregnancy
• Triggers production of prolactin
• Used by fetal adrenal gland to produce cortisol and aldosterone
• Decreases uterine muscle excitability
• Increases mother’s respiratory rate to offset increased CO2 produced by heightened metabolic demand
Chearskul 2006
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Hormonal Changes
• Relaxin
• Increases
• “decreases uterine muscle contractility by reducing the activity of uterine myosin kinase”
• Softens the cervix and causes pelvic joint laxity
• Boosts activity of collagenase enzyme
• May also have renal effects
• “renal vasodilation, hyperfiltration, and reduced myogenic activity of small renal arteries”
Chearskul 2006
Hormonal Changes• Insulin
• 1st half of pregnancy: Mom has greater sensitivity to insulin
• 2nd half of pregnancy: Mom is in state of insulin resistance• Shift to fat metabolism for Mom
• More plasma glucose and AA which facilitates uptake by the placenta to fetus
• Estrogens, progesterone, placental growth hormone, and cortisol also influence insulin resistance
• Gestational Diabetes occurs in ~4% of pregnancies
• Prolactin• Progressive increase throughout pregnancy
• Regulates fat metabolism
• Renin Angiotensin System• Increased Na+ retention
• Contributing factor to development of preeclampsiaChearskul 2006
Hormonal Changes
• Elevated cortisol
• Facilitates fat storage in Mom
• Stimulates development of mammary glands
• Increased thyroid hormones and ACTH from pituitary
Chearskul 2006
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Stretch of the Abdominal Wall
• Growing fetus=growing uterus=abdominal wall expansion
• Hypertrophy of type I fibers & increased proportion of type I fibers shown in animal studies (Lalatta Costerbosa et al 1988)
Physical Activity
• ACOG guidelines
• Advocate the CDC recommendation of “150 minutes of moderate-intensity aerobic activity every week”.
• Contraindications to exercise
• “certain types of heart and lung diseases”
• Incompetent cervix
• Multiple gestation
• Risk factors for preterm labor
• Placenta previa (after 26 weeks)
• Preterm labor/rupture of membranes
• Preeclampsia
• Severe anemia
• Benefits of Exercise
• Decreased back pain
• Combats constipation
• “may decrease risk of gestational diabetes, preeclampsia, and cesarean delivery”
• Maintain healthy weight
• General cardiovascular benefits
• “helps you lose the baby weight after your baby is born”
• Advocate continued exercise after delivery to decrease risk of DVT and to manage weight
http://www.acog.org/Patients/FAQs/Exercise-During-Pregnancy
The Physical Activity Problem
• 68% of pregnant women report decreased physical activity
• 80% of postpartum women report significant decline in physical activity level
(Gutke 2011)
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Big Picture Impact on the Musculoskeletal System
• Ligamentous laxity• Pelvis
• Wrists
• Decreased fascial integrity• DRA
• Impaired force transfer• Brown & McGill study
• Increased fatigability?• Gracovetsky 2008
• Fiber type shift?• Animal studies
Definition of Pelvic Girdle Pain• Location: between posterior iliac crest and gluteal fold
• SIJ
• Pubic symphysis
• Posterior thigh
• Symptoms: decreased tolerance of sitting, standing, walking
• Confirmed by:• Ruling out lumbar spine as pain generator
• Reproduction of symptoms with the following tests:• Posterior Pelvic Pain Provocation test (P4)
• Patrick’s FABER
• Palpation of long dorsal ligament
• Gaenslens Test
• Modified Trendelenburg Test
• Palpation of pubic symphysis
• Active Straight Leg Raise (ASLR) Test
Vleeming 2008
Prevalence & Impact of PGP
• Prevalence in pregnant women: 20-23% (Albert 2000)
• 50-75% if include LBP (Wu 2004, Wang 2004, Kristiansson 1996)
• Long term concerns:
• 25% of pregnant women with PGP will continue to have pain in the postpartum period (Ostgaard et al 1996, Albert et al 2001, Wu et al 2004)
• 20% of women will avoid a future pregnancy due to severe PGP (Brynhildsen1998)
• Worldwide, 1 in 4 women have chronic pelvic pain (Nygaard et al 2008)
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Clinical Assessment of PGP in Pregnancy
• Posterior Pelvic Pain Provocation test (P4)
• Patrick’s FABER
• Palpation of long dorsal ligament
• Gaenslens Test
• Modified Trendelenburg Test
• Palpation of pubic symphysis
• Active Straight Leg Raise (ASLR) Test
Posterior Pelvic Pain Provocation (P4)Posterior Pelvic Pain Provocation (P4)Posterior Pelvic Pain Provocation (P4)Posterior Pelvic Pain Provocation (P4)• Patient supine on plinth
• Hip flexed to 90 degrees, knee relaxed
• Stabilize CL pelvis
• Downward pressure through long axis of femur
• Positive test: reproduction/exacerbation of posterior pelvic pain
• 0= no pain
• 1 (mild) = complaint of pain without physical manifestation of pain
• 2 (moderate) = complaint of pain with physical manifestation of pain
• 3 (unbearable)= unable to complete test due to patient withdrawal
Ostgaard et al 1994
Patrick’s FABERPatrick’s FABERPatrick’s FABERPatrick’s FABER
• Patient supine on plinth
• Leg brought into Flexion, ABduction, External Rotation
• Gentle overpressure applied at end-range (“forced FABER”)
• Positive Test: reproduction/exacerbation of posterior pelvic pain (SIJ) or pubic symphysis
Albert et al 2000
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Palpation of long dorsal SIJ ligamentPalpation of long dorsal SIJ ligamentPalpation of long dorsal SIJ ligamentPalpation of long dorsal SIJ ligament
• Patient in sidelying with slight hip and knee flexion
• Position in prone for postpartum women
• Palpate along length of the ligament
• Positive test: Provocation/exacerbation of pain
• 0= no pain
• 1 (mild) = complaint of pain without physical manifestation of pain
• 2 (moderate) = complaint of pain with physical manifestation of pain
• 3 (unbearable)= unable to complete test due to patient withdrawal
Albert et al 2000
GaenslensGaenslensGaenslensGaenslens TestTestTestTest
• Two options for positioning (modify for pregnancy)
• One leg in flexion, CL leg brought into extension, mild overpressure on both legs
• Positive test: reproduction/exacerbation of posterior pelvic pain (especially SIJ) on side of extended leg
www.clinicalgate.com
Vleeming et al 2008
Laslett et al 2005
Laslett 2008
Modified Trendelenburg TestModified Trendelenburg TestModified Trendelenburg TestModified Trendelenburg Test
• Patient in standing
• PT stands behind patient
• One leg brought into flexion
• Positive test: pain in pubic symphysis.
• Drop of pelvis CL to stance leg (functional hip weakness)
Albert et al 2000
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Palpation of Pubic SymphysisPalpation of Pubic SymphysisPalpation of Pubic SymphysisPalpation of Pubic Symphysis
• Patient can be in supine, semi-reclined, sidelying
• Clinician palpates pubic symphysis
• Positive test: Reproduction/exacerbation of pain at pubic symphysis
Albert et al 2000
Active Straight Leg Raise (ASLR) Test
• Patient supine on plinth with legs extended
• Raise one leg at a time (heel height of 20 cm)
• Patient rates difficulty• 0= not difficult at all• 1= minimal difficulty• 2= somewhat difficult• 3= fairly difficult• 4= very difficult• 5= unable to lift leg off plinth
• If difficulty is rated above a zero, therapist provides manual compression to the pelvis and the test is repeated
• Positive Test: Decrease in reported difficulty with manual pelvic compression
www.dianelee.ca
Mens 2012
Treatment
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Switching Gears: Research Presentation
Abdominal Muscle Function in Postpartum Women
Rita Deering, DPT, PhDc
Doctoral Candidate, Clinical & Translational Rehabilitation Health Science Program, Department of Physical Therapy, Marquette
University
http
://ww
w.xsig
ht.co
m.a
u
The Abdominal Muscles Are EssentialThe Abdominal Muscles Are EssentialThe Abdominal Muscles Are EssentialThe Abdominal Muscles Are Essential
• Synergists of Pelvic Floor Muscles
• Assist with breathing
• Regulate Intra-Abdominal Pressure
• Essential for lumbopelvic stability
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“The Core”
� Middle of the kinetic chain
� Link between the upper and lower extremities
� Transfer of energy from upper to lower extremities (Kibbler 1998)
Labor and Delivery: Core Disruption
(Ashton-Miller 2009)
Vaginal delivery
Cesarean delivery
Traditional Postpartum Visit in the USTraditional Postpartum Visit in the USTraditional Postpartum Visit in the USTraditional Postpartum Visit in the US
• Pelvic Exam
• Assessment of uterine involution
• Assessment of soft tissue healing
• Perineum
• Surgical site
• Pap Smear
• Discussion regarding birth control
6 Weeks Postpartum6 Weeks Postpartum6 Weeks Postpartum6 Weeks Postpartum
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• Abdominal dysfunction has not been well quantified• Not much research on effects of pregnancy has been done on human subjects
• Strength/force testing that has been done on humans is not very objective
• Most abundant abdominal muscle research focuses on presence and degree of Diastasis Recti Abdominis (DRA)
“Common” is often dismissed as “normal”
• Does function of the abdominal muscles change after pregnancy?
• Force production
• Trunk flexion
• Torque-Angle Curve
• Fatigability
Research QuestionsResearch QuestionsResearch QuestionsResearch Questions
• What factors contribute to function of the abdominal muscles after pregnancy?
• Mode of delivery
• DRA
• Activity level
• Pain
• Body composition
• Muscle thickness
• Muscle activation
• Time since delivery
Research QuestionsResearch QuestionsResearch QuestionsResearch Questions
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Hypotheses
• In comparison to controls, postpartum women will:
• Demonstrate decreased strength during a maximal voluntary isometric trunk flexion contraction
• Be more fatigable, as evidenced by a shorter time to task failure
• Have thinner rectus abdominis muscles
• Report decreased physical activity
• Over the course of 16 weeks:
• Postpartum women will demonstrate an improvement in strength and fatigability, but will remain weaker and more fatigable than control women
Final Test
Sessions
(24-26 wks
postpartum)
Protocol: Laboratory Measures of Strength and Fatigability
MVC
60
sec
50% MVC
target line
(16.4 Nm)
To
rqu
e
MVCMVC
Protocol: Clinical Measures of Strength and Fatigability
http://classconnection.s3.amazonaws.com/385/flashcards/1258385/png/trunk_flexion1330632161223.png
http://2.bp.blogspot.com/-Vo1_sKLqWZ0/UYQIkN2lBfI/AAAAAAAAAIQ/Rdz_SLPhVhA/s1600/5030J1+Jamar+Hydraulic+Hand+Dynamometer.jpg
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Protocol: Laboratory Measure of Muscle Thickness
RESULTSRESULTSRESULTSRESULTS
Initial Time Point (8-10 weeks postpartum): 15 Control (25.3 + 5.2 years), 29
Postpartum (31.4 + 5.2 years) women
Follow Up Time Point (24-26 weeks postpartum): 14 Control (25.4 + 5.8 years), 28
Postpartum (32.0 + 5.1 years) women
Postpartum Women (8-10 Weeks PP): 18 vaginal delivery, 11 Cesarean Delivery
Postpartum Women (24-26 Weeks PP): 17 vaginal delivery, 11 Cesarean Delivery
Body Composition
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Visceral Adipose Tissue
Postpartum Control
Volu
me
(in
3)
0
10
20
30
40
50
Visceral Adipose Tissue
Postpartum Control
Ma
ss (
lb)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
****
Visceral Adipose Tissue
Postpartum Control
Ma
ss (
lb)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Visceral Adipose Tissue
Postpartum Control
Vo
lum
e (
in3)
0
10
20
30
40
50
INITIAL
FOLLOW
UP
*
*
Thickness of Right Rectus Abdominis Muscle Belly
Position Relative to Umbilicus
2.5 cm Above 2.5 cm Below
Thic
kness (
cm
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2 Postpartum
Control
***
Thickness of Right Rectus Abdominis Muscle Belly
Position Relative to Umbilicus
2.5 cm Above 2.5 cm Below
Thic
kne
ss (
cm
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2 Postpartum
Control
**
Physical Activity
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Quantification of Moderate Physical Activity
ActiGraph
Postpartum Control
Ave
rage
min
ute
s/d
ay
0
10
20
30
40
50
60
Physical Activity Quantification
ActiGraph
Postpartum Control
Ave
rage
ste
ps/d
ay
0
2000
4000
6000
8000
10000
12000
**
Physical Activity QuantificationActiGraph
Postpartum Control
Ave
rage
ste
ps/d
ay
0
2000
4000
6000
8000
10000
Quantification of Moderate Physical ActivityActiGraph
Postpartum Control
Avera
ge m
inu
tes/d
ay
0
10
20
30
40
*
INITIAL
FOLLOW
UP
Self-Reported Physical Activity
Over the Last 12 Months
Postpartum Control
ME
T h
ours
/we
ek
0
10
20
30
40
50
60
*
Self-Reported Physical ActivityOver the Last 12 Months
Postpartum Control
ME
T h
ou
rs/w
ee
k
0
10
20
30
40
50
*
INITIAL FOLLOW UP
Inter-Recti Distance
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Inter-Recti DistanceMeasured with Ultrasound
Position (relative to umbilicus)
4 cm above
2.5 cm above
2.5 cm below4 cm below
Dis
tance
(cm
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Control
Postpartum
INITIAL
Control n=16, Postpartum n=19
Position p<0.001
Position x Group p=0.025
Group p<0.001
FOLLOW UP
Control n=15, Postpartum n=21
Position p<0.001
Position x Group p=0.056
Group p<0.001
Inter-Recti DistanceMeasured with Ultrasound
Position (relative to umbilicus)
4 cm above
2.5 cm above
2.5 cm below4 cm below
Dis
tance (
cm
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Control
Postpartum
Pain Testing
Pressure Pain Threshold
Nailbed of Left Middle Finger
Postpartum Control
Thre
sho
ld (
KP
a)
0
50
100
150
200
250
300
350
Pressure Pain Threshold
Lower Abdomen
(Site of Pfannenstiel Incision)
Postpartum Control
Thre
sho
ld (
KP
a)
0
50
100
150
200
250
***
Pressure Pain ThresholdLower Abdomen
(Site of Pfannenstiel Incision)
Postpartum Control
Thre
sho
ld (
KP
a)
0
50
100
150
200
250
Pressure Pain Threshold
Nailbed of Left Middle Finger
Postpartum Control
Thre
sho
ld (
KP
a)
0
50
100
150
200
250
300
**
INITIAL
FOLLOW
UP
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29
Change in Pressure Pain Threshold From Before to After Exercise
Upper Abdominal Site
PreEx PostEx
Pre
ssure
Pa
in T
hre
sho
ld (
KP
a)
100
120
140
160
180
200
220
240
260
Control
Postpartum
INITIAL
Control n=15, Postpartum n=28
Time p=0.001
Time x Group p=0.195
Group p=0.005
Change in Pressure Pain Threshold From Before to After ExerciseUpper Abdominal Site
PreEx PostEx
Pre
ssure
Pain
Thre
shold
(K
Pa)
80
100
120
140
160
180
200
220
Control
Postpartum
FOLLOW UP
Control n=14, Postpartum n=26
Time p=0.003
Time x Group p=0.472
Group p=0.018
Functional Tests
Six Minute Walk Test Performance
Postpartum Control
Dis
tance (
m)
0
200
400
600
800
*
Six Minute Walk Test Performance
Postpartum Control
Dis
tance
(m
)
0
200
400
600
800
INITIAL FOLLOW UP
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30
Strength
Hand Grip Strength
Right Left
Grip S
trength
(lb
s)
0
20
40
60
80
100Postpartum
Control
Hand Grip Strength
Right Left
Gri
p S
trength
(lb
s)
0
20
40
60
80
100Postpartum
Control
INITIAL
FOLLOW UP
Trunk Flexor Strength
Maximum Voluntary Isometric Contraction
Pre-Fatiguing Exercise
Postpartum Control
Torq
ue (
Nm
)
0
10
20
30
40
50
60
Manual Muscle Testing Strength Grade
1 2
Str
ength
Gra
de
0
1
2
3
4
5
Postpartum Control
*
**
Trunk Flexor StrengthMaximum Voluntary Isometric Contraction
Pre-Fatiguing Exercise
Postpartum Control
Torq
ue (
Nm
)
0
10
20
30
40
50
60
Manual Muscle Testing Strength Grade
1 2
Strength
Gra
de
0
1
2
3
4
5
Postpartum Control
**
INITIAL
FOLLOW
UP
9/19/2016
31
Torque Angle Curve
Torque-Angle Curve of the
Trunk Flexor Muscles
Position (degrees)
-50 -40 -30 -20 -10 0 10 20 30
Torq
ue (
Nm
)
0
20
40
60
80
100
Postpartum
Control
INITIAL
Control n=13, Postpartum n=28
Position p<0.001
Position x Group p=0.927
Group p<0.001
Torque-Angle Curve of theTrunk Flexor Muscles
Position (degrees)
-50 -40 -30 -20 -10 0 10 20 30
To
rque
(N
m)
10
20
30
40
50
60
70
80
Postpartum
Control
FOLLOW UP
Control n=16, Postpartum n=25
Position p<0.001
Position x Group p=0.909
Group p=0.003
Fatigue Task
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32
Fatigability of the Trunk Flexor Muscles
Postpartum Control
Tim
e t
o T
ask
Failu
re (
s)
0
200
400
600
800
**
Fatigability of the Trunk Flexor Muscles
Postpartum Control
Tim
e to T
ask F
ailu
re (
s)
0
200
400
600
800
*INITIAL
FOLLOW UP
Impact of Method of DeliveryImpact of Method of DeliveryImpact of Method of DeliveryImpact of Method of Delivery
Fatigability of the Trunk Flexor Muscles
Vaginal Delivery
Cesarean Delivery
Tim
e t
o T
ask F
ailure
(s)
0
50
100
150
200
250
300
Fatigability of the Trunk Flexor Muscles6 Months Postpartum
Vaginal Delivery
Cesarean Delivery
Tim
e t
o T
ask F
ailu
re (
s)
0
100
200
300
400
P=0.004
P=0.523
Recovery of MVC Torque After Fatiguing Exercise
Task Failure r10 r20
MV
C (
% B
aselin
e)
60
70
80
90
100
110
120Control
Postpartum
INITIAL
Control n=15, Postpartum n=26
Time p=0.023
Time x Group p=0.036
Group p=0.139
FOLLOW UP
Control n=13, Postpartum n=27
Time p<0.001
Time x Group p=0.969
Group p=0.122
Recovery of MVC Torque After Fatiguing Exercise
Task Failure r10 r20
MV
C (
% B
aselin
e)
60
70
80
90
100
110
120Control
Postpartum
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33
Impact of Method of DeliveryImpact of Method of DeliveryImpact of Method of DeliveryImpact of Method of DeliveryTrunk Flexion MVC RecoveryVaginal vs Cesarean Delivery
Time
Task Failure r10 r20
MV
C T
orq
ue (
% B
aselin
e M
VC
)
70
75
80
85
90
95
100Cesarean Delivery
Vaginal Delivery
Trunk Flexion MVC RecoveryVaginal vs Cesarean Delivery
6 Months Postpartum
Time
Task Failure r10 r20
MV
C T
orq
ue (
% B
aselin
e M
VC
)
60
70
80
90
100
110
120
130
Vaginal Delivery
Cesarean Delivery
Time P=0.775
Time x Delivery Type
P=0.592
Delivery Type P=0.829
Time P=0.016
Time x Delivery Type
P=0.309
Delivery Type P=0.081
Recovery of MVC Torque After Fatiguing Exercise
Task Failure r10 r20 Baseline
MV
C T
orq
ue (
Nm
)
10
20
30
40
50
60 Control
Postpartum
INITIAL
Control n=15, Postpartum n=26
Time p<0.001
Time x Group p<0.001
Group p=0.001
Recovery of MVC Torque After Fatiguing Exercise
Task Failure r10 r20 Baseline
MV
C T
orq
ue
(N
m)
10
20
30
40
50
60 Control
Postpartum
FOLLOW UP
Control n=13, Postpartum n=27
Time p<0.001
Time x Group p=0.248
Group p<0.001
Steadiness of contraction
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Force Fluctuations of Trunk Flexion Contractionsat Five Target Intensities
Coefficient of Variation of Torque
Target Intensity (% MVC)
0 10 20 30 40 50 60 70 80
CV
of
Torq
ue (
%)
0
5
10
15
20
25
30
35
40Control
Postpartum
INITIAL
Control n=15, Postpartum n=23
Intensity p<0.001
Intensity x Group p=0.020
Group p=0.009
Force Fluctuations of Trunk Flexion Contractionsat Five Target Intensities
Coefficient of Variation of Torque
Target Intensity (% MVC)
0 10 20 30 40 50 60 70 80
CV
of
Torq
ue (
%)
0
10
20
30
40
50Control
Postpartum
FOLLOW UP
Control n=15, Postpartum n=25
Intensity p<0.001
Intensity x Group p=0.219
Group p=0.039
Correlations
Association Between Maximal Strength and Fatigability of the Trunk Flexor Muscles
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400
MV
C S
trength
(N
m)
0
20
40
60
80
100
120r=0.602
p<0.001
N=44
Association Between Maximal Strength and Fatigability of the Trunk Flexor Muscles
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400 1600
MV
C S
trength
(N
m)
0
10
20
30
40
50
60
70
80
r=0.415
p=0.006
N=42
INITIAL
FOLLOW UP
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35
Association Between Trunk Flexor Fatigability andBody Fat Percentage (DXA)
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400
Body F
at (%
)
20
25
30
35
40
45
50
55
r=-0.342
p=0.023
N=44
Association Between Trunk Flexor Fatigability andBody Fat Percentage (DXA)
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400 1600
Bo
dy F
at
(%)
20
25
30
35
40
45
50
55
r=-0.402
p=0.008
N=42
INITIAL
FOLLOW UP
Association Between Trunk Flexor Fatigability andInter-Recti Distance at 4 cm Below the Umbilicus
(Measured with Ultrasound)
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400 1600
IRD
(cm
)
-1
0
1
2
3
4
5 r=-0.346
p=0.031
N=39
INITIAL
FOLLOW UP
Association Between Trunk Flexor Fatigability andInter-Recti Distance at 4 cm Below the Umbilicus
(Measured with Ultrasound)
Time to Task Failure (s)
0 200 400 600 800 1000 1200 1400
IRD
(cm
)
-1
0
1
2
3
4
5r=-0.405
p=0.011
N=40
Association Between Trunk Flexor Maximal Strength and Thickness of Right Rectus Abdominis Muscle at 2.5 cm
Above the Umbilicus(Measured with Ultrasound)
MVC Strength (Nm)
0 20 40 60 80 100 120
Mu
scle
Th
ickn
ess (
cm
)
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6r=0.311
p=0.040
N=44 Association Between Trunk Flexor Maximal Strength and
Thickness of Right Rectus Abdominis Muscle at 2.5 cm
Above the Umbilicus
(Measured with Ultrasound)
MVC Strength (Nm)
0 10 20 30 40 50 60 70 80
Muscle
Thic
kne
ss (
cm
)
0.4
0.6
0.8
1.0
1.2
1.4r=0.388
p=0.012
N=41
9/19/2016
36
Association Between Trunk Flexor Maximal Strength andClinical Assessment of Abdominal Muscle Strength
(Manual Muscle Testing)
MVC Strength (Nm)
0 20 40 60 80 100 120
MM
T S
tre
ng
th G
rad
e
0
1
2
3
4
5
r=0.532
p<0.001
N=43
Association Between Trunk Flexor Maximal Strength andClinical Assessment of Abdominal Muscle Strength
(Manual Muscle Testing)
MVC Strength (Nm)
0 10 20 30 40 50 60 70 80
MM
T S
tre
ngth
Gra
de
0
1
2
3
4
5
r=0.621
p<0.001
N=38
Discussion
• Clinical implications of pregnancy & postpartum?
• Other clinical insights
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