Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy

Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
MCN   Clinical Issues
                                                                                   Volume 13, Number 2, pp. 248-262
                                                                                   @2002, MCN

          Inactivity: Symptoms Associated
          With Gastrocnemius Muscle
          Disuse During Pregnancy
          Judith A. Maloni, PhD, RN, FAAN;
          Barbara St. Pierre Schneider, DNSc, RN

 II   This longitudinal study assessed change               gastrocnemius muscle reoxygenation after
      in gastrocnemius muscle metabolism                   exercise significantly increased across
      across antepartum bed rest and recovery              antepartum bed rest (t = -2.1, P < .05) and
      during the first 6 weeks postpartum as               significantly decreased during the 6-week
      well as symptoms during recovery.The                 postpartum period (t = 1.83, P < .05).
      convenience sample consisted of 65                   Women who were on bed rest prior to
      pregnant women, hospitalized on bed                  hospital admission had significantly higher
      rest for a mean of 24.8 days (range 5-70             reoxygenation scores upon enrollment (t =
      days). A dual wavelength hemoglobin!                 -8.6, P < .05). Symptoms of postpartum
      myoglobin spectrophotometer and                      muscle soreness, deconditioning, and
      ergometer assessed muscle                            difficulty with mobility were reported.
      reoxygenation times after plantar flexion            Postpartum assessment and rehabilitation
      exercise from hospital admission through             are needed to facilitate recovery and
      6 weeks postpartum. The Postpartum                   prevent long-term injury. (KEYWORDS:
      Symptom Checklist assessed symptoms                  pregnancy, bed rest, inactivity, muscle
      of muscle deconditioning.The time for                disuse, muscle deconditioning)

Each year approximately 700,000 pregnant                  women who have been on antepartum bed
women are prescribed antepartum bed rest                  rest are discharged from the hospital without
for prolonged periods despite the lack of ev-             an assessment of possible side effects, ad-
idence of its effectiveness.l-4 Bed rest ther-            vice about recovery, or a planned program
apy during pregnancy is prescribed from                   of rehabilitation.3,7 To date, there has been
weeks to several months by 89% to 92% of
obstetricians, and the majority of them are               ..........
unaware of the side effects of this                          From the Frances Payne Bolton School of Nursing,
treatment.' However, the physiologic side ef-             Case Western Reserve University, Cleveland, Ohio (Dr
fects of various types of activity restriction in         MalonD; and the School of Nursing, University of Wis-
                                                          consin, Madison (Dr Schneider).
nonpregnant individuals are widely recog-
nized.6 Many obstetric healthcare providers                  Reprint requests to Judith A. Maloni, PhD, RN,
                                                          FAAN, Case Western Reserve University, Frances
believe that because women are young and                  Payne Bolton School of Nursing, 10900 Euclid Av-
healthy prior to pregnancy the effects of in-             enue, Cleveland, OH 44106-4904 (e-mail: jam44@po.
activity are negligible. Thus, after birth,     

Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
Vol. 13, No.2 May 2002                                 PREGNANCY MUSCLE DISUSE             .   249

minimal research examining the side effects       induces significant change.9-11Deterioration
of bed rest therapy among pregnant                in the musculoskeletal system begins rapidly
women.8 Only one study provides evidence          within 6 hours of bed rest.I4-16Absolute loss
that pregnant women demonstrate physio-           of muscle mass and protein peaks during 3
logic side effects of bed rest that are similar   to 7 days,17The most profound areas of atro-
to those identified in nonpregnant popula-        phy are in the postural muscles of the legs
tions.3 Documentation of physiologic side         and back. 6.18-20Greater loss occurs with even
effects of bed rest in pregnant women is im-      longer periods of inactivity.ll.18.19After 5
portant because bed rest treatment may            weeks of bed rest, there is a 27% loss of
place women at risk for both short- and           strength in the plantar flexor muscles, in-
long-term disability. Therefore, the purpose      cluding the soleus and gastrocnemius.17 In
of this study was to assess change in gastroc-    one study, subjects demonstrated a 9% loss
nemius muscle metabolism across antepar-          in muscle volume in the lower back group,
tum bed rest and postpartum recovery and          16% to 18% in the quadriceps and hamstring
to describe the prevalence of symptoms as-        groups, 20% in the ankle flexors, and 30% in
sociated with recovery from musculoskeletal       the ankle extensors after 17 weeks of space
deconditioning after bed rest.                    flight.19The arms appear to be affected to a
                                                  lesser degree but significant atrophy occurs
                                                  if bed rest is prolonged.6,21Although there is
o Review of Literature                            considerable variability in subjects, muscle
                                                  volume loss appears to reach a steady state
Inactivity occurs on a continuum ranging          or plateau at approximately 4 months of
from reduced activity to complete immobi-         space flight.19
lization.6 Bed rest is one type of activity re-       Differing models for the study of disuse
striction and has been the focus of extensive     atrophy reveal similar changes in muscle
research. Aerospace scientists have used bed      mass, protein, and strength. In animals, fiber
rest as a model to study the effects of           type and metabolic property changes occur
weightlessness in space.9-11Research across       in atrophied muscles.22,23For example, atro-
more than 40 years documents that bed rest        phied soleus muscle has fewer slow-twitch
induces changes in every human physiologic        fibers.23 Disuse muscle atrophy induces in-
system.9-11The cause of bed rest side effects     creased anaerobic capacity in slow-twitch
is unclear but believed to be due to several      and fast-twitch oxidative glycolytic fibers of
factors. These factors include the lack of        the soleus and gastrocnemius, respectively.23
weight bearing on the skeleton; decreased         Data from a space flight study suggest simi-
postural cues to the different organ systems;     lar changes in anaerobic capacity in slow-
decreased number and magnitude of muscle          twitch fibers of the vastus latera lis muscle.24
contractions, particularly of the postural        Therefore, it is possible that bed rest may in-
muscles: and a headward bodily fluid              duce alterations in muscle metabolism prop-
shift.9.11The major adverse effect of bed rest    erties of pregnant women.
is a general physical deconditioning mani-            Much is still unknown about recovery
fested, in part, by alterations in circadian      from inactivity because ethical issues limit
rhythms and in cardiopulmonary, immune,           the duration of bed rest research and space
hormonal and musculoskeletal systems.9-11         flights are limited to small numbers of sub-
Bed rest also results in insulin resistance in    jects.6 However, recovery appears to be pro-
the muscle and liver of women.12,13Of con-        longed whether induced by bed rest or
cern is that muscle contraction initiates glu-    space flight.8.9.11Like initial deconditioning,
cose uptake. Thus, whole body glucose             various organ systems recover at different
homeostasis may be altered by bed rest.12.13      rates.6.9.19Recovery begins with remobiliza-
Being totally confined to bed, or in a Tren-      tion and occurs slowly. In a study of 4 crew
delenberg position, increases the severity of     members after an 8-day space flight, ham-
side effects.3.6.9                                string and lower back muscles were still be-
    Organ systems deteriorate at different        low baseline at 2 weeks after recovery.I8
rates across the same length of bed rest.         During Mir space flights of 115 to 197 days,
However, evena shortdurationof inactivity         recovery of muscle volume was completed
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
250   .   MALONI AND ST PIERRE                                             AACN Clinical Issues

 for most individuals by 30 to 60 days after           Because the majority of bed rest research
 flight.19 However, these results should be in-    has been conducted on males and none on
 terpreted with caution as many astronauts         pregnant women, it was unknown whether
 conducted intensive exercise during flight to     pregnant women also experience muscu-
 offset anticipated losses.                        loskeletal changes induced during bed rest
     In a laboratory study of muscle recovery,     and recovery from bed rest. During the last
 lower limb suspension was used to study the       decade, research has begun to document the
effects of muscle disuse. Six men were             side effects of antepartum bed rest; however,
 placed on 4 weeks of lower limb suspension        this research has primarily focused on the
to mimic the effects of space flight. How-         psychosocial side effects.35-38There is only
ever, after 7 weeks of recovery, the ability to    one published study documenting the physi-
maintain force output was not fully                ologic effects of bed rest during pregnancy.3
restored.25 Although muscle mass had re-           Outcomes for 17 women on antepartum bed
turned to normal, endurance remained sub-          rest were compared with those for 18
optimal. Of further concern, it is not known       healthy pregnant women who were not pre-
whether the changes in musculoskeletal sys-        scribed bed rest. Variables included antepar-
tem are totally reversible.ll.19                  tum and postpartum muscle reoxygenation
    Based primarily on animal studies, recov-     time after exercise and postpartum symp-
ery from muscle atrophy, in addition to be-       toms of muscle recovery. Results revealed
ing prolonged, appears to involve further         that the time needed to reoxygenate the gas-
muscle injury.6.26-30  Muscle damage and in-      trocnemius muscle after a short bout of plan-
flammation are evident soon after the re-         tar flexion exercise increased as the length
sumption of normal weight bearing.29.30Ex-        of bed rest increased and decreased once
ercise has been shown to cause muscle             bed rest was terminated. Muscle reoxygena-
damage, especially during the first week of       tion times for the control group remained
recovery.26.27It is possible that the damage      low and stable across time. During recovery,
occurs because the resumption of normal           women who had been on bed rest reported
weight bearing or exercise initially may be       symptoms of deep muscle soreness of the
too strenuous for atrophied muscles. Strenu-      back, legs, arms, heels, and knees. Two
ous activity, especially that involving muscle    women experienced symptoms of a muscle
lengthening, induces an acute muscle injury.      tear. All women on bed rest had difficulty
Similar to an exercise-induced muscle injury,     walking, especially with ascending and de-
repair and remodeling of the injured atro-        scending stairs, while none in the control
phied muscle occur eventually.29.31               group experienced these symptoms.
    Several symptoms, including muscle sore-          An additional national retrospective study
ness, swelling, and edema, are associated         supports these findings (J.A.M., unpublished
with recovery from muscle atrophy. These          data, 2002). A randomly selected sample of
symptoms are similar to those experienced         89 women who were prescribed antepartum
by individuals who have undergone strenu-         bed rest completed a checklist identifying
ous or unaccustomed exercise. 32 Muscle           the symptoms experienced during postpar-
soreness usually develops within 24 to 48         tum recovery. Symptoms experienced by
hours, peaks at 72 hours, then subsides at 5      more than 50% of women included back
to 7 daYS.33Soreness is believed to be associ-    muscle soreness; difficulty walking and in
ated with muscle tissue damage. LeBlanc19         negotiating stairs, particularly when ascend-
states that sore leg muscles often are re-        ing; dizziness; shortness of breath; and fa-
ported after both short and long space            tigue. Symptoms that were reported by more
flights. Muscle cramps, tears, strain, chronic    than 25% of women included muscle sore-
pain, and fatigue may be common during re-        ness in arms, heels, knees, and upper and
covery.33.34Swelling may be due to several        lower leg muscles; knee buckling; swollen
causes including inflammation or pooling of       ankles or feet; and difficulty descending
body fluids in the lower limbs. 19Thus, a vari-   stairs. Nine percent of women reported post-
ety of symptoms appear to occur during re-        partum falls. Thus, current evidence suggests
covery from muscle disuse and the cause(s)        that pregnant women who are prescribed
of these symptoms vary.                           antepartum bed rest experience symptoms
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
Vol. 13, No.2 May 2002                                  PREGNANCY MUSCLE DISUSE             .   251

associated with muscle deconditioning dur-         ing the postpartum, women who have previ-
ing recovery, similar to those experienced in      ously been on antepartum hospital bed rest
nonpregnant populations.                           will demonstrate a decrease in muscle re-
   The presence of adverse physiologic ef-         oxygenation time after exercise from an-
fects of antepartum bed rest that extend into      tepartum discharge through 6 weeks post-
postpartum recovery is of concern for three        partum as measured by T 1/2 muscle
reasons. First, antepartum bed rest is pre-        reoxygenation time. An additional research
scribed for large numbers of women.2 Sec-          question was to describe the symptoms as-
ond, research has failed to document the ef-       sociated with muscle deconditioning and re-
fectiveness of bed rest for improving              covery across the postpartum period.
fetal/infant or maternal mortality or morbid-
           Third, current data, which is consis-
tent with that of aerospace research, now          o Methods
suggest that antepartum bed rest treatment
has significant side effects. However, an-         Women treated with antepartum bed rest
tepartum bed rest therapy continues to be          were assessed for symptoms of muscle dys-
prescribed without apparent regard for these       function using a repeated measures longitu-
effects. 2,5                                       dinal design.
    Side effects such as muscle atrophy may
place women at increased risk for long-            Subjects
term sequelae such as permanent muscle
damage. Women may also be at risk for              The convenience sample consisted of 65
fractures and an early osteoporosis as bed         women who were studied from enrollment
rest also induces bone 10SS.9,19Whether            upon      antepartum      hospital    admission
such bone loss is totally reversible is not        through 6 weeks postpartum. The data pre-
known.1l,28 There is some evidence for an-         sented here are for a subset of subjects who
tepartum depression3 and for adverse an-           participated in a larger study of the physio-
tepartum psychosocial effects on the hus-          logic and psychosocial side effects of an-
band and the family.4,40If further evidence        tepartum bed rest. Subjects were recruited
about the adverse physiologic and psy-             from the antepartum inpatient units of three
chosocial side effects of antepartum bed           tertiary care, university affiliated hospitals in
rest is supported, it would suggest that an-       two midwestern cities. Pregnant women di-
tepartum bed rest treatment should not be          agnosed with a pregnancy complication
prescribed because it is both ineffective          who were prescribed bed rest were eligible
and iatrogenic. Therefore, the specific            to participate. Criteria for inclusion were
aims of this study were to determine               women who were between 21 and 33 weeks
whether women on antepartum bed rest               gestation, at least 16 years of age, healthy
demonstrate       change in gastrocnemius          prior to pregnancy, 'and able to read and
muscle metabolism across time from an-             speak English. Subjects were limited to
tepartum hospital admission through 6              women with the diagnosis of preterm labor,
weeks postpartum, and to describe the              preterm rupture of membranes, placenta
symptoms indicative of muscle decondition-         previa, placental abruption, incompetent
 ing and recovery in the postpartum period.        cervix, multiple gestation, or a combination
                                                   of these conditions. Women were excluded
                                                   if they had any acute or chronic metabolic
o Hypotheses                                       disease such as chronic hypertension, preg-
                                                   nancy-induced hypertension, asthma, dia-
During the antepartum, pregnant women on           betes mellitus, an admission diagnosis of
hospital bed rest will demonstrate an in-          gestational diabetes, or any impairment in
crease in muscle reoxygenation time after          muscle function or mobility.
exercise from hospital admission through               Subjects were primarily white (63.1%),
the end of antepartum hospitalization, as          and married (60%), with ages ranging from
measured in TI/z muscle reoxygenation time          16 to 40 (mean 28.0, SD 6.8). Years of mater-
(TI/z = one half of the time in seconds). Dur-      nal education ranged from 8 to 21 (mean
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
252   .   MALONI AND ST PIERRE                                                     AACN Clinical Issues

 13.9, SD 2.9) and 36% of women had                   globin! myoglobin (Hb/Mb) spectropho-
household incomes at or below $30,000.                tometer (Runman) invented by Dr Britton
Most women were multigravidas (80%), al-              Chance of the University of Pennsylvania.
though only half of these had a living child.        The Runman was used in the investigator's
Women were diagnosed with preterm labor              previous study and differentiated muscle re-
(27.7%); preterm labor combined with an-             oxygenation after short-term exercise for
other of the above inclusion pregnancy di-           women on bed rest and that of the control
agnoses (33.8%); preterm rupture of mem-             group of pregnant women not on bed rest.3
branes (18.5%); placenta previa (7.7%);                  The Runman examines muscle metabo-
placental abruption (3.3%); or a combination         lism by measuring oxygenation/deoxygena-
of non-preterm labor diagnoses (9%). Eigh-           tion of muscle tissue. The Runman has been
teen percent of the pregnancies were multi-          used to assess oxygenation of tissue in adult
ple gestations. The gestational age of the           brain after circulatory arrest after pacemaker
pregnancy upon hospital admission ranged             removal,41 as well as the oxygenation of the
from 21 to 33 weeks (mean 28.4; SD 3.0),             fetal brain,42 and respiratory muscle.43 The
whereas the mean gestational age at birth            Runman also has been used to assess reoxy-
was 34.1 weeks (SD 3.3) and ranged from 24           genation of the quadriceps of 22 elite com-
to 40 weeks. Sixty-six percent of women had          petitive male and female rowers44 and in
a vaginal delivery, 21.1% had an elective ce-        three studies of the gastrocnemius muscle of
sarean section, and 12.3% had an emergency           non-pregnant, non-bed rest, subjects.45-47
cesarean section. The length of hospital bed         Although the capability of the Runman to
rest ranged from 5 to 70 days (mean 24.77,           assess deoxygenation/reoxygenation          re-
SD 14.6). Twenty-six women (40%) were on             sponses in a variety of populations has been
bed rest at home prior to hospital enrollment        validated, norms for various populations
for a mean length of 22.7 days (SD 18.24,            have not yet been established.
range 2-89).                                             The Runman pulses near red light waves
                                                     (760 and 850 nm) through superficial tissue
Measures                                             to obtain signals from the Hb/Mb content of
                                                     the muscle during exercise and exercise re-
A list of variables and instruments used to          covery.44The difference in absorption at the
assess them is given in Table 1                      two wavelengths approximates desaturation
    MUSCLE METABOLISM. Measurement of mus-           of Hb/Mb during exercise and resaturation
cle disuse in high-risk pregnant women               during recovery.44,48-50A small-rubberized
placed on bed rest presented unique chal-            encasement (probe) about the size of a large
lenges as standard methods of muscle as-             wristwatch containing silicon diodes and in-
sessment involve rigorous activity and are           terference filters is placed over the muscle
contraindicated.3 Anthropometric measure-            and secured by a Velcro band. Light waves
ment, muscle biopsy, and magnetic reso-              penetrate through superficial tissue to pick
nance imaging were considered but re-                up signals of deoxygenation and resatura-
jected because of lack of reliability,               tion of the muscle. The Runman is combined
excessive cost or discomfort, or potential           with a portable ergometer (pedal) to con-
danger to the fetus. Therefore, muscle me-           duct plantar flexion exercise so that patterns
tabolism was assessed using the new exper-           of deoxygenation in response to exercise
imental noninvasive dual wavelength hemo-            can be observed. Signals of oxygenation and

             TABLE1.           Study Variablesand Instruments
           Variable                                  Instrument

           Muscle metabolism              Hemoglobin/myoglobin spectrophotometer    and
           Postpartum muscle symptoms     Postpartum symptoms checklist
           Postpartum mobility            Postpartum symptoms checklist
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
Vol.13, No.2 May 2002                                     PREGNANCYMUSCLEDISUSE                   .      253

deoxygenation are recorded by a strip chart         muscle fatigue. The exercise took on the av-
recorder (Figure 1). The amount of time in          erage approximately 3 minutes and did not
seconds needed to recover from exercise to          induce full body fatigue. Monitoring and
a baseline level of reoxygenation after exer-       graphing of reoxygenation of muscle after
cise divided by 2 (T 1/2 recovery time) is          exercise took an additional 2 minutes. The
used as the score.44 Longer muscle reoxy-           exercise did not appear to affect decondi-
genation times indicate prolonged recovery          tioning resulting from muscle disuse.
from oxygen-induced debt stimulated by ex-              POSTPARTUM   SYMPTOMS.   Postpartum symp-
ercise.44 Use of the Runman poses no risk or        toms associated with muscle disuse were as-
discomfort to the person.                           sessed with a self-report Postpartum Symp-
   Two teams of two data collectors tested          tom Checklist. The checklist consists of 49
subjects in their hospital rooms using a stan-      items, which assess the influence of bed rest
dardized protocol.3 One directed the exer-          upon the various organ systems. Only symp-
cise while the other operated the Runman            toms associated with muscle disuse (n = 12)
and strip chart recorder. Women sat in bed          or mobility (n = 7) are reported here. The
in a semi-Fowlers position with legs ex-            checklist was developed by the investigator
tended and knees fixed (Figure 2). The gas-         based on clinical experience with women on
trocnemius muscle was used for assessment           bed rest and from an extensive review of the
of muscle disuse because it is a postural           literature on bed rest and pregnancy. Items
weight-bearing muscle. It consists of pre-          assessing mobility were adapted from re-
dominately slow oxidative Type I fibers that        search with the elderly5253as a simple, effec-
alter their contractile speed and enzymatic         tive, and inexpensive method of assessing
capacity when weight bearing is removed. 51         gross mobility problems among young,
This muscle is superficial to the skin and          healthy subjects had not been developed.
thus is easily accessible for measurement.          Items assess whether the person (1) needs
The probe was placed over the gastrocne-            support to walk; (2) hesitates before walk-
mius muscle and covered with a lightly              ing; (3) walks using each foot alternately; (4)
wrapped ace bandage to prevent the escape           experiences difficulty with knees buckling;
of light. Women conducted intermittent              has difficulty (5) ascending or (6) descend-
plantar flexion exercises by pressing on a          ing stairs; or (7) has difficulty transferring to
pedal against 10 pounds of pressure for a           a sitting position. Appropriateness of the
distance of 5 inches. Plantar flexions were         items was judged by peer review. Items
executed once every 10 seconds until a              were tested and revised to include other
baseline of deoxygenation was achieved,             symptoms identified in the pilot study. In a
then once every 5, 2, and 1 second, and then        subsequent study, the Postpartum Symptom
maximal effort until the woman reported             Checklist distinguished symptoms between

Figure1. Patternfor deoxygenationduringexercisetestingandreoxygenationduring   recovery from exercise.
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
254   .   MALON! AND ST PIERRE                                                 AACN Clinical Issues

                                Hb/Mb Spectrophotometer

                                                        Strip      Figure 2. Setup for spectrophotome-
                                                      Recorder     ter (Runman) testing.

women on bed rest and pregnant women                 data collection, with the exception of two
who did not receive bed rest.4 Cronbach al-          days after delivery, occurred in the subjects'
pha was established at O. 84. The symptom            homes. A baseline measure of muscle me-
checklist was administered by the data col-          tabolism was obtained upon hospital admis-
lector and scored as present or absent. The          sion, and at the end of the antepartum, and
checklist took approximately 3 to 4 minutes          at 6 weeks postpartum. Postpartum symp-
to complete.                                         tom data were collected at 2 days after deliv-
    DEMOGRAPHICS.  An expanded form of the           ery and weekly through 6 weeks. Demo-
Demographic and Medical History Instru-              graphic and perinatal data were obtained
ment3 was used to obtain descriptive data            upon enrollment and updated using the
from the hospital record and from patient in-        medical record as new conditions emerged.
terview. Information about maternal demo-            Subjects received a $50 incentive for partici-
graphic and perinatal characteristics includ-        pating in the study.
ing sample descriptor variables such as
previous history of home and hospital bed
rest for this and previous pregnancies was           o Statistical Analyses
    PROCEDURE. The medical records of poten-         Data were analyzed using the Statistical
tial subjects were screened for their appro-         Package for the Social Sciences (SPSS) 10.0
priateness for entry into the study. Informed        for windows. Descriptive statistics and Stu-
consent was obtained after study approval            dent t tests were computed. Power was cal-
by the Human Subjects Boards. Enrollment             culated for the larger study containing multi-
of subjects occurred over a 3.5-year period.         ple variables and nine hypotheses. 54For the
Six weeks of data collector training was con-        current analysis. hypotheses were directed
ducted prior to enrollment of subjects. After        for one group of bed-rested women with
training, data collectors had to successfully        three assessments across time. However,
assess gastrocnemius muscle metabolism us-           upon analyzing the perinatal data we de-
ing the Runman on 10 different women, at             tected a change in the characteristics of the
least 3 of whom had to be on bed rest. Due           bed rest treatment across the study. When
to the complexity of the Runman instrument,          the study was initiated, pregnant women
procedural reliability was reassessed approx-        were admitted directly to the hospital for
imately every 2 months on a random sched-            bed rest and remained there until delivery.
ule. Interrater reliability for the Postpartum       However, across time home bed rest began
Symptom Checklist was established and re-            to be prescribed prior to hospital admission.
assessed quarterly to maintain reliability of        As a result the sample consists of both
0.95.                                                women whose bed rest was started upon
                                                     hospitalization (n = 39) and women whose
Data Collection                                      bed rest was initiated prior to hospitalization
                                                     (n = 26). Because muscle atrophy occurs
Antepartum data collection took place while          rapidly,l1 the sample was divided into these
each subject was hospitalized. Postpartum            tWo groups for part of the analysis to detect
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
Vol. 13, No.2 May 2002                                 PREGNANCY MUSCLE DISUSE              .   255

the influence of home bed rest prior to ad-       bed rest subjects was not appropriate at this
mission. Thus using a one tailed t test, alpha    time, as they may represent values of a pop-
set at 0.05, posthoc power was estimated at       ulation to which generalization about effects
0.52 with an effect size of 0.45.                 need to be made.
    Given that the power was low but the ef-
fect size was moderate to high, options were
considered to address the low power. De-          o Results
creasing within group variability would in-
crease power. However, the Runman is a            During antepartum bed rest, the length of
new experimental assessment tool. The va-         time needed for women's gastrocnemius
lidity of the tool for assessing oxygenation!     muscle to reoxygenate after exercise signifi-
deoxygenation of tissue has been estab-           cantly increased from hospital admission
lished but the range of normal values has         through discharge (t = -2.1, P < .05). In
not yet been established. Furthermore, the        contrast, the length of time needed for post-
state of. the science in understanding the        partum muscle reoxygenation after exercise
physiologic effects of muscle atrophy upon        significantly decreased (t = 1.83, P < .05).
pregnant women is limited. In the absence         Figure 3 demonstrates the pattern of change
of norms, the variability in muscle reoxy-        across the three time periods. Despite signif-
genation scores might represent some factor       icant differences in muscle reoxygenation
as yet unknown. Thus, we were hesitant to         scores across time, women's scores demon-
eliminate outliers.                               strated great variability. The type of delivery
    Furthermore, although the standard devi-      (ie, vaginal versus cesarean section) did not
ations for muscle reoxygenation scores were       influence postpartum muscle reoxygenation
large, similar standard deviations were found     scores.
in a previous study of 31 healthy pregnant            Because 40% of the women were on
women using the Runman (J.A.M., unpub-            bed rest prior to hospital admission, sub-
lished data, 2002). Whether or not the range      jects were divided into two groups. The
of values contains true outliers is unknown       groups consisted of those women who
at this time. However, strip chart recordings     were not on bed rest prior to hospital ad-
for eight subjects who appeared to have ex-       mission (n = 39) and those who were (n =
treme outliers were reviewed. Three test          26). Muscle reoxygenation scores were sig-
scores were eliminated due to a scoring er-       nificantly higher upon enrollment for those
ror. The remaining tests appeared to be valid     who had previously been on bed rest (t =
and were included in the data set. Therefore,     -8.6, P < .05) but not significantly different
it was decided that elimination of outliers for   at the end of the antepartum or postpartum

 E 44
  = 42
 .E 36
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
256    .       MALONI AND ST PIERRE                                      AACN Clinical Issues

periods. Figure 4 depicts the patterns for       (Table 4). Support to walk was needed
muscle reoxygenation scores for the two          across the first week postpartum for a num-
groups. Variability among reoxygenation          ber of women and more than 40% needed
scores was greater among women who               help to sit. Initially, more than 50% of
were prescribed home bed rest prior to           women hesitated before beginning to walk.
hospital admission (Table 2).                    Most women (77%) began using stairs during
   The prevalence of musculoskeletal de-         the first week at home. Difficulty negotiating
conditioning symptoms occurring from 2           stairs started at this time. For some women,
days after delivery through 6 weeks postpar-     stair-climbing difficulties and knee buckling
tum is listed in Table 3. Soreness in weight-    persisted across 6 weeks postpartum.
bearing postural muscles dominated the
symptoms reported by women. Soreness in
back and neck muscles, followed by upper         o Discussion
and lower leg soreness, were reported most
frequently and decreased across 6 weeks. A       The current study demonstrates that in-
large percentage of women also initially re-     creases in the time needed for the gastrocne-
ported arm muscle soreness. At 6 weeks           mius muscle to reoxygenate during the an-
postpartum, 45% of women were still experi-      tepartum decrease during the first 6 weeks
encing back muscle. soreness and 21% had         postpartum. Additionally, the development
persistent neck muscle soreness. Only a few      of symptoms of recovery from muscular de-
women reported muscle tears. Fatigue,            conditioning and difficulty with mobility
pedal edema, and shortness of breath on ex-      during the first 6 weeks postpartum was
ertion were greatest immediately after birth     confirmed in the current study. These results
with only high levels of fatigue remaining at    support the supposition that muscle atrophy
6 weeks.                                         occurs during antepartum bed rest and re-
    Assessment of mobility revealed that dur-    covers with remobilization.6.9.1l,28Using a
ing postpartum women experienced diffi-          summary of studies, Fortney et al9 created a
culty in all seven areas of walking, which       composite description of physiologic re-
rapidly improved across 6 weeks postpartum       sponses during bed rest recovery. They re-

E: 42

      38   i                /                       "-                  1-      Bedrest
                                                                                No Prior
      34   I
           1          /                                                 1- -Prior

Eo-   32

           First                   Last                       Last
      Antepartum               Antepartum                 Postpartum
Figure 4. Gastrocnemiusmuscle reoxygenationtime afterexerciseforwomenwho wereprescribedbed rest
prior to hospitalizationand thosewhowerenot.
Inactivity: Symptoms Associated With Gastrocnemius Muscle Disuse During Pregnancy
Vol. 13, No.2     May 2002                                            PREGNANCYMUSCLEDISUSE                          .   257

    TABLE2.           Variabilityin MuscleReoxygenation Scores
                                 First Antepartum                 Last Antepartum               Last Postpartum
                                    Mean ~ SO                       Mean ~ SO                     Mean ~ SO

No previous bed rest                31.04::t: 15.43                 41.72::!: 16.66               34.59 ::!: 16.36
Previous bed rest                   39.64 ::!:23.24                 39.78:!:     19.88            36.69 ::!:22.56

port that subjects demonstrated generalized                      on home bed rest were significantly higher
weakness; poor exercise tolerance; distur-                       at admission but no additional change oc-
bance of coordination, posture, and gait;                        curred across hospitalization. The lack of
foot pain; difficulty standing without sup-                      change in the prior bed rest group suggests
port: difficulty walking; and leg pain. The                      that, at some point, bed rest atrophy reaches
current study results agree with this compos-                    a plateau similar to astronauts.19 This finding
ite and confirm our previous findings for                        is also consistent with reports that other or-
pregnant women on bed rest.3.39Study re-                         gan systems adapt physiologically to this
sults also support findings of atrophy in non-                   state across time.9,1l
pregnant subjects on bed rest or those par-                         Longer inactivity is usually accompanied
ticipating in space flight.9.11.18-20
                                    In women                     by greater atrophy and longer recovery, 11,19
without a prior bed rest history, the steep in-                  so it was expected that a longer period of in-
crease in muscle reoxygenation times across                      activity would proportionally affect muscle
the antepartum supports the rapid onset of                       metabolism as evidenced by a prolonged
muscle deconditioning or atrophy soon after                      muscle reoxygenation time. Muscle reoxy-
bed rest is started.9.11,18-20                                   genation scores for women on home bed
    Comparisons for the two groups of                            rest prior to admission remained slightly ele-
women, one of which had been on bed rest                         vated at six weeks postpartum. However, no
prior to admission, reveal additional under-                     significant difference in postpartum muscle
standing of the muscle atrophy process. The                      reoxygenation was detected between the
muscle reoxygenation scores for the women                        two groups of women. It is possible that no

   TABLE 3        .   Postpartum        Symptoms of Deconditioning
                           Delivery* Week 1           Week 2         Week 3         Week 4      Week 5        Week 6
                             n=62          n=60       n=64           n=58           n=64        n=62          n=64
                            No. (%)       No. (%)     No. (%)       No. (%)         No. (%)     No. (%)       No. (%)

Upper legs sore             24 (38.7)     21 (35.0)   17 (26.6)       8 (13.8)       8 (12.5)    3 (4.8)      4 (6.3)
Lower legs sore             18 (29.0)     24 (40.0)   15 (23.4)      12 (20.7)       8 (12.5)    5 (8.1)      5 (7.8)
Arms sore                   17 (27.4)     15 (25.0)   10(15.6)        6 (10.3)       7 (10.9)    5 (8.1)      8 (12.5)
Neck sore                   21 (33.9)     20 (33.3)   15 (23.4)      14 (24.1)      17 (26.6)   11 (17.7)    14 (21.9)
Back sore                   44 (71.0)     35 (58.3)   27 (42.2)      23 (39.7)      25(39.1)    24 (38.7)    29 (45.3)
Heel sore                   13 (21.0)     11 (18.3)    7 (10.9)       5 (8.6)        7 (10.9)    6 (9.7)      5 (7.8)
Knee sore                    9 (14.5)      7 (11.7)    7 (10.9)       7 (12.1)       8 (12.5)    9 (14.5)     8 (12.5)
Muscle cramps               28 (45.2)     18 (30.0)   13 (20.3)       5 (8.6)        9 (14.1)    3 (4.8)      9 (14.1)
Muscle tears                 0(0)          1 (1.7)     1 (1.6)        0(0)           1 (1.6)     0(0)          1 (1.6)
Shortness of breath         23 (37.1)     19(31.7)    16 (25.0)       8 (13.8)       6 (9.4)     8 (12.9)     6 (9.4)
Fatigue                     46 (74.2)     44 (73.3)   40 (62.5)     32 (55.2)       32 (50.0)   27 (43.5)    34(53.1)
Pedal edema                 26 (41.9)     24 (40)     11 (17.2)       6 (10.3)       6 (9.4)     6 (9.7)      4 (6.3)

"Delivery time point was measured postpartum day 2,
258     .   MALONI        AND ST PIERRE                                                    AACN Clinical   Issues

   TABLE 4 . Postpartum                 Mobility Symptoms
                            Delivery* Week 1           Week 2         Week 3     Week 4    Week 5    Week 6
                             n=62          n=60        n=64          n=58        n=64      n=62      n=64
                             No. (%)       No. (%)     No. (%)       No. (%)     No. (%)   No. (%)   No. (%)

Hesitates before walking     34 (54.8)     26 (43.3)    8 (12.5)      3 (5.2)    4 (6.3)   1 (1.6)    2 (3.1)
Needs support to walk        19 (30.6)     12 (20.0)    3 (4.7)       2 (3.4)    1 (1.6)   1 (1.6)    1 (1.6)
Knees buckle                  8 (12.9)      8 (13.3)    6 (9.4)       4(6.9)     3 (4.7)   4 (6.5)    4 (6.3)
Needs support to             28 (45.2)     15 (25.0)    6 (9.4)       3 (5.2)    1 (1.6)   2 (3.2)    2 (3.1)
   sit down
Does not alternate           10 (16.1)      7 (11.7)    3 (4.7)       2(3.4)     3 (4.7)   2 (3.2)    1 (1.6)
      feet when walking
Difficulty ascending          3(4.8)       20 (33.3)   13 (20.3)      9 (15.5)   6 (9.4)   4 (6.5)    5 (7.8)
Difficulty descending         3 (4.8)      16 (26.7)    7 (10.9)      5 (8.6)    5 (7.8)   2 (3.2)    5 (7.8)

"Delivery time point was measured postpartum day 2.

difference was detected because of the large                      Further research regarding women's symp-
variability in reoxygenation scores, because                      toms after 6 weeks postpartum is needed.
both groups reached the maximum amount                               Postpartum soreness in neck and arms is
of atrophy at the last antepartum measure-                        somewhat surprising. Neck muscle soreness
ment, or because muscle metabolism as                             was reported in our previous study3 but
measured by reoxygenation time after exer-                        LeBlanc et aP8.19expressed surprise at failing
cise does not increase linearly with longer                       to find neck muscle soreness as the head is
inactivity. A larger sample size, more precise                    heavy. However, during space flight, the full
measurement of the amount of time spent                           weight of the head is still supported by the
out of bed, and more frequent measurement                         neck whereas during bed rest, the bed and
of reoxygenation time during the antepar-                         pillow support the head most of the time.
tum period may resolve this issue. Consider-                      Neck muscle soreness could also be a result
ation of variations in the sample such as age,                    of pushing during delivery as even small
ethnicity, and weight might also shed light                       amounts of strenuous exercise can induce
into this finding.                                                muscle damage during recovery. Arm mus-
    Muscle soreness in the various postural                       cle soreness is not ordinarily expected in
muscles dominated initial postpartum recov-                       bed rest lasting less than 60 days.6 During
ery. This finding is consistent with reports                      the antepartum period, women use their
that muscle tissue damage occurs during re-                       arms for a number of self-care activities.
mobilization.19.28.34Because a large percent-                     However, during the postpartum period
age of women continued to experience                              women often report that they use their arms
back and neck muscle soreness at 6 weeks                          to pull themselves up stairs and as crutches
postpartum, it suggests that long-term, more                      when descending stairs, sitting down, or
serious muscle damage, or prolonged recov-                        during toilet transfer. Arm muscle soreness
ery form injury has occurred. It is possible                      may result from greater antepartum atrophy
that female hormonal shifts that women ex-                        than has been reported among nonpregnant
perience during the postpartum may be, in                         populations or muscle injury during the
part, responsible. Preliminary animal evi-                        postpartum activities to compensate for leg
dence suggests that female hormones may                           muscle weakness.
affect leukocyte infiltration, an important                           Postpartum fatigue during recovery is not
 process for the recovery of injured muscle.55                    surprising but is likely to be confounded
Long-term muscle soreness also may indicate                       with childrearing fatigue. Lee and Zaftke56
that muscle atrophy is not entirely reversible.                   report high levels of fatigue among healthy
Vol. 13, No.2 May 2002                                  PREGNANCY MUSCLEDISUSE             .   259

mothers because of fragmented sleep. Fur-          o Nursing Implications
ther study may reveal whether the fatigue
experienced by those previously on bed rest        The implications of these findings for nurs-
is different in magnitude or quality.              ing are numerous. In the absence of elimi-
    Postpartum symptoms disappeared rapidly        nating pregnancy bed rest treatment, a com-
for most women. Women are highly moti-             mon thought is to prevent atrophy by using
vated to resume ambulation to care for the         antepartum exercise. Astronauts have at-
infant. Early ambulation may be helpful in         tempted to do so but have only been par-
                                                   tially successful. 6.28 The type of exercise
restoring function but women may be prone
to falls. This is of grave concern for two rea-    needed to offset atrophy is intensive and in-
sons. First, women may be carrying their in-       volves heavy resistance training.6 This type
                                                   of exercise is not conunonly used by healthy
fants and both could be injured during a
fall. Second, aerospace research shows a           women and is currently contraindicated dur-
strong correlation between bed rest induced        ing a high-risk pregnancy. However, an-
muscle loss and bone loss, with recovery of        tepartum      exercise   involving increased
bone lagging behind that of muscle.6.9.19          weight bearing might help reduce muscle at-
Thus, during resumption of walking women           rophy. In addition, a systematic assessment
                                                   of muscle weakness and an accompanying
may also be at risk for fractures, particularly
at the point when muscles have reached             program of postpartum rehabilitation may
                                                   facilitate recovery and prevent long-term in-
their maximal strength but bone has not.6
    Women's muscle reoxygenation scores            jury of muscle and bone.
                                                       After inactivity, the goal is to enable
exhibited a large degree of variability across
                                                   women to return to a normal level of physi-
time, especially for those on previous home
                                                   cal activity without injury.34 A number of
bed rest. Several explanations could account       measures will facilitate maternal recovery
for this finding. First of all, aerospace re-
                                                   and are suggested for nursing practice.
searchers have found variability in muscle
                                                   These include assessing for:
atrophy obtained by a variety of assessment
methods.19 Researchers using the Runman in
nonpregnant samples have also found large
                                                   .   the type of physical activity conducted
                                                       prior to bed rest to know what kinds of
variability (personal communication,
Chance, March, 2001). However, the vari-
                                                   .   activity the woman will resume;
                                                       the duration of home and hospital bed rest
ability for our pregnant sample is somewhat
larger than expected. The variability could
be due to measurement error, variations in
                                                   .   and the severity of activity restriction;
                                                       muscle weakness to determine which
                                                       muscle groups are most seriously af-
the length of bed rest among the sample
(range 5-70 hospital days), or the influence
of subject activity. All women were allowed
                                                   .   fected by bed rest;
                                                       symptoms of difficulty walking, de-
                                                       creased strength, fatigue, and other
out of bed each day to go to the bathroom              symptoms associated with muscle recov-
and it is not uncommon for women to walk
to the bathroom 10 to 13 times per day.
While such trips usually last 5 minutes or
                                                   .   ery and ambulation-induced injury;
                                                       symptoms of postpartum depression asso-
                                                       ciated with postpartum loss of function
less, some women linger for longer periods.            and independence or antepartum stress;
Variability could also indicate that preg-
nancy might influence muscle metabolism
in some way that is not yet understood. A
                                                   .   family problems related to the stress of
                                                       having a high-risk pregnancy.
large degree of variability was also demon-             Nurses also should advise the woman to:
strated in our study of healthy pregnant
women who were not on bed rest (J.A.M.,            .   begin weight-bearing activity to facilitate
unpublished data, 2002). Additional re-
search is needed to clarify these issues. Fur-     .   recovery;                          .

                                                       remobilize carefully to avoid overusing
ther research is needed to define the range
of normal values for deoxygenation re-
sponse to exercise among healthy and high-
                                                   .   muscles and inducing further damage;
                                                       exert caution as there is a potential for
                                                       falls due to knee buckling and decreased
 risk pregnant women.                                  leg strength;
260   .   MALONI AND ST PIERRE                                               AACN Clinical Issues

·   rebuild back and leg muscles through
    gradual exercise as these muscle groups
                                                 to document women's postpartum com-
                                                 plaints about muscle dysfunction, muscle

·   are most likely to be weak;
    consult with a healthcare professional
    who is familiar with both exercise and
                                                 soreness, physical limitations that inhibit en-
                                                 gagement in activities, and the time at which
                                                 women reach full postpartum functional ca-
    assessment of muscle function and de-        pacity after antepartum bed rest.

·   conditioning about postpartum exercise;
    exert caution even when muscle groups
    reach normal functioning as bone mass is     o Summary
    still in the process of restoration;
·   expect limited strength, fatigue, and        Pregnant women who are prescribed bed
    muscle soreness as a result of pregnancy     rest experience significant changes in mus-

·   bed rest treatment;
    report symptoms after bed rest to their
    healthcare provider;
                                                 cle metabolism while hospitalized and a sig-
                                                 nificant reversal of these changes in the
                                                 postpartum. The postpartum period is also
·   use acetaminophen, if possible, instead      characterized by symptoms commonly asso-
    of nonsteroidal anti-inflammatory drugs      ciated     with    recovery     from    muscle
    (NSAIDS) for symptom relief, as NSAIDS       atrophy / deconditioning. Numerous nursing
    may interfere with macrophage function       actions can facilitate maternal postpartum re-

·   and delay recovery from injury;
    expect that fatigue might occur during
    physical activity and that function, inde-
                                                 covery and prevent long-term injury to mus-
                                                 cle and bone.

    pendence, and mobility eventually will       Acknowledgments
    be restored;
·   increase sufficient protein intake to en-    This study is funded by a grant from the Na-
    sure muscle repair, especially in later      tional Institute of Health, National Institute
    part of the muscle recovery period.          of Nursing Research ROI-NRO-3323. The au-
                                                 thor thanks Sarah Korkowski for her assis-
Patient referrals will be necessary for:         tance.
·   an in-depth assessment of muscle weak-
    ness and development of a planned pro-
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