The Spine Journal 9 (2009) 39–46

Physical demand levels in individuals completing a sportsperformance-based work conditioning/hardening

program after lumbar fusion

Keith Cole, PT, DPT, MBiomedE*, Matt Kruger, MS, CSCS, Dylan Bates, PT, MSPT, CSCS,Greg Steil, EP, Mike Zbreski, MS, CSCS

Athletic and Therapeutic Institute, Research and Development, 6105 North Lincoln Avenue, Chicago, IL 60659, USA

Received 8 February 2008; accepted 20 July 2008

Abstract BACKGROUND CONTEXT: Pain and disab

FDA device/drug

The authors ackno

interest as follows: K

DB, GS: ATI Physica

1529-9430/09/$ – see

doi:10.1016/j.spinee.2

ility after lumbar fusion surgery contributes to theover $20 billion dollars spent in health-care costs and estimated $28 billion in lost wages annually.With the goal of returning to work, an intensive program designed to build functional strength maybe used. Previous interventions for this subgroup report the outcome measure of return to work(RTW), but do not account for the physical demand of the job to which they are returning. Thismay account for varying RTW and re-injury rates.PURPOSE: To examine the effectiveness of a sports performance-based work conditioning/hard-ening (SPWC/H) program on increasing an individual’s strength measured by achievement of phys-ical demand level (PDL) job classification of individuals followed by workers’ compensationhaving had lumbar fusion surgery.STUDY DESIGN/SETTING: An uncontrolled multicenter, retrospective observational study ofvisits from 1999–2002 in an outpatient physical therapy setting.PATIENT SAMPLE: Fifty-four patients having undergone lumbar fusion surgery, managed byworkers’ compensation, that successfully completed a SPWC/H program.OUTCOME MEASURE: Physiologic measures: Deadlift and overhead press lifts, defined asmaximum weight, a patient is able to lift between 8 and 15 repetitions. Functional measures:Calculated deadlift and overhead press volume (DLv, OHv) and estimated one repetition maximum(DLm, OHm). Physical demand level (PDL) for first (pre) and last week (post) are defined as: light(L!20 lb occasionally), light/medium (LMO20 lb occasionally), medium (M, 50 lb occasion-ally), medium heavy (MH, 75 lb occasionally), heavy (H, 100 lb occasionally), and very heavy(VHO100 lb occasionally), where ‘occasionally’ for the purposes of this article, is defined as inthe 8–15 repetition range.METHODS: Patients completed a greater than or equal to 4 week, 4–5 days/wk, SPWC/Hprogram. This program combines traditional concepts of strength and endurance training of workconditioning (WC) and hardening (WH) programs, with the sports performance concept of period-ization in resistance training volume and intensity. Best set overhead and press lifts were obtainedfrom each patient during the first and last week of the program.RESULTS: Significant increase between pre- and post-DLv, DLm, OHv, and OHm (all p!0.0001)existed when grouping all subjects. When adjacent groups are merged into M/MH and H/VH,significant differences existed between groups and pre- and postlifts (p!0.05). There was a medianincrease of three classifications when grouping by pre-PDL. There was no difference in outcomesfound by grouping by single or multiple levels fused. Overall, numbers in each starting PDL were:41 (75.9%) light, 6 (11.1%) LM, and 7 (13%) in medium. Numbers ending in each PDL groupwere: 1 (1.9%) light, 2 (3.7%) LM, 7 (13%) medium, 19 (35.2%) medium/heavy, 5 (9.3%) heavy,and 20 (37%) at very high.

status: not applicable.

wledge a financial relationship or possible conflict of

C, MZ: ATI Physical Therapy (holds position); MK,

l Therapy (board of directors).

* Corresponding author. Athletic and Therapeutic Institute, Research

and Development, 6105 North Lincoln Avenue, Chicago, IL 60659,

USA. Tel.: (773) 279-0927; fax: (773) 279-0951.

E-mail address: Keith.Cole@atipt.com (K. Cole)

front matter � 2009 Elsevier Inc. All rights reserved.

008.07.007

40 K. Cole et al. / The Spine Journal 9 (2009) 39–46

CONCLUSIONS: Post-lumbar spinal fusion patients are typically at the light PDL (!20 lb occa-sionally) on completion of traditional physical therapy program. After an SPWC/H program,significant increase strength of deadlift and overhead lift volume and one repetition maximumdemonstrated a median three-level increase in classification of PDL. We were also able to determinethat there was no difference in strength outcome between those with a single- vs. multiple-levelfusion surgery. Although the vast majority of individuals entered the program at the lowest PDL(20 lb or less occasionally), more than 80% of patients completed the program at PDL of medium(50 lb occasionally) or above, and 37% of patients achieved the maximum PDL (over 100 lb occa-sionally). Future studies are needed to determine if increases in strength determined by PDLclassification such as these relates to increased RTW rates and decreased re-injury rates. � 2009Elsevier Inc. All rights reserved.

Keywords: Lumbar fusion; Work conditioning; Work hardening; Physical demand level; Workers’ compensation

Introduction

Low back pain (LBP) is a common affliction with a prev-alence rate of 60–85% in our society, with about 15%(12–30%) of adults having LBP at any one time [1,2].When back pain lasts longer than 3 months (defined aschronic back pain) detrimental personal and financial impli-cations can occur including increased use of medicalresources and costs, increased time off work, and disability[3,4]. Treatment for diagnoses causing LBP remains some-what controversial and variable. Although many nonopera-tive and operative techniques are available, outcomesstudies are not always able to distinguish the most appropri-ate treatment or combination of treatments of diagnosescausing back pain ranging from acute to chronic [5–13].When nonoperative treatments fail, a surgical option ofspinal fusion (LF) may be performed. Success rates andfunctional outcomes for lumbar fusion vary greatly, withlimited demonstration of efficacy vs. nonsurgical interven-tion. Interventions are usually measured with qualitativescores of pain and perceived function and disability[14–16].

The workers’ compensation system allows for a meansto follow a specific subgroup of patients that were injuredon the job. Workers’ compensation systems cover 127million US workers with an estimated annual cost for backpain of $20–$50 billion. Lumbar injuries result in approxi-mately 149 million lost work days/year; about 2/3 of thesedays are caused by occupational injuries. The annualproductivity losses resulting from lost work days are esti-mated to $28 billion [17,18]. Unfortunately, the immenserange of injuries and treatment techniques, as well as thehardship in navigating the workers’ compensation systemin the United States, produces a difficult environment tocollect quality outcome data. Individuals having undergonelumbar fusion, managed by the workers’ compensationsystem, are of particular interest in this study. Previousstudies regarding this population have been published thatdemonstrate improved outcomes compared with matchedcontrols [19], with increased qualitative assessment scores[14]. These studies rarely address strength obtained by eachof the individuals.

After traditional physical therapy, for those who remainwith physical limitations preventing ability to return to work(RTW), focus changes from improving function with activi-ties of daily living, to restoration of work-related functionthrough a work conditioning (WC) or work hardening(WH) program [20]. A WC program is defined as a singledisciplinary treatment approach to address physical or func-tional needs using physical conditioning and functional activ-ities related to work. WH programs are defined asa multidisciplinary model of care designed to address physi-cal, functional, behavioral, and vocational needs, and usesreal or simulated work activities. Each program is 4–8 h/d,4–5 days/wk for approximately 4–8 weeks. The outcomemeasure of each of these programs is generally RTW status.

These programs have few quality studies demonstratingeffectiveness and efficacy. A review of studies by Weiret al., provided contradictory evidence that clinic-basedWC/H programs indeed improve the RTW of more chroni-cally disabled workers in the long term [21]. AlthoughRTW is the main outcome measure defined by the Ameri-can Physical Therapy Association (APTA) and the Occupa-tional Health Guidelines, the physical demand level (PDL)of the work to which they are returning is not considered orcontrolled for. Few of the studies attempted to grossly clas-sify individuals into a labor worker, involving a probableincreased PDL. They did not, however, separate RTW orre-injury rates based on the patient’s strength and matchof physical capacity to job PDL.

This study examines the effectiveness of a sportsperformance-based work conditioning/hardening (SPWC/H)program on increasing an individual’s strength, measured byachievement of PDL job classification, of individuals followedby workers’ compensation having had lumbar fusion surgery.

Patients and methods

Study design

An uncontrolled, multicenter, retrospective, observa-tional study of visits from 1999–2002. Treatment sessionstook place in the setting of outpatient physical therapy

ContextFollowing lumbar fusion and completion of post-opera-tive physical therapy, some patients remain functionallyweak and this may impact their ability to return to nor-mal activities.

ContributionThis uncontrolled, retrospective chart review of 54 pa-tients suggests that the majority of such patients can sig-nificantly increase their strength if they work tocomplete an intensive program aimed at building func-tional strength.

ImplicationsThis study design primarily serves to generate furtherresearch hypotheses. Does an increase in strength cor-relate well with improved general health and economicoutcomes such as performing activities of daily living,return to work, reducing medication usage, or avoidingrecurrent disability? If improving strength also im-proves outcomes, who needs formal training and whodoes not? Is the observed increase in strength due tothe training program or a non-specific effect? Howdoes this method compare to other rehabilitation strat-egies? Is this only a consideration in work’s compensa-tion setting?

dTSJ Editors

41K. Cole et al. / The Spine Journal 9 (2009) 39–46

clinics. Patient files were obtained from storage andreviewed for information described in the study.

Patients

Subjects of this study included 54 patients from the agegroup 20–58 years, status postlumbar fusion of single ormultiple lumbar levels. Patients were not grouped by pre-surgical condition, nor by surgical approach. Each patientcompleted greater than or equal to 4 weeks, 4–5 days/wk(mean of 31.4616.7 visits) of an SPWC/H program. Allwere off work after spinal fusion operation.

Inclusion criteria

1) At least one lumbar level surgically fused, 2) completionof traditional physical therapy, 3) physician referral for WC orWH, 4) approval of coverage from workers’ compensation in-surance, and 5) no previous lumbar fusion surgery.

Exclusion criteria

1) Non-compliance or inability to perform program atleast 4 h/d, 4–5 days/wk and 2) inability to complete atleast 4 weeks full progression SPWC/H program.

Collected data and outcome measures

During the first and the last week, the best effort set ofeach: a deadlift (DL) and an Overhead Press (OH) wasobtained. Each patient was instructed to give their besteffort for each lift. The best effort set was defined as a setof the exercise (weight and repetitions) of three trials at thegreatest weight that a person is able to perform for at least8 repetitions. Each patient’s first week PDL classification(pre-PDL) and last ending PDL classification (post-PDL)was determined by using the ‘‘occasional’’ liftingdescriptors based on the United States Department of Labor(DOL). Classifications are: light (L!20 lb), light/medium(LMO20 lb), medium (M, 50 lb), medium/heavy (MH,75 lb), heavy (H, 100 lb), and very heavy (VH, O100 lb;Table 1), where LM and MH are industry wide additional de-scriptors not identified by the DOL. Classification was deter-mined by the weight of the first and last weeks’ deadlift set.

Each patient was also classified by the levels of fusion.Number of levels of fusion was recorded and divided into

Table 1

Physical demand level definitions defined by occasional lifting abilities

Physical demand level

Occasional lifting

requirement/ability (weight [lb])

lifting ability in 8–12 repetitions

Light !20

Light medium O20

Medium 50

Medium heavy 75

Heavy 100

Very heavy O100

single level of lumbar fusion (S) or greater than one levelof lumbar fusion (M).

Calculations

To be able to compare deadlift (DL) and overhead (OH)lifts between patients and between pre- and postinterven-tion states, the set volume and the predicted one repetitionmaximum (1 RM) were calculated. The set volume wascalculated as:

Volume5weight� repetitions 1

The 1 RM max was calculated using the Brzyckiformula:

1 RM5weight� 36=ð37 repetitionsÞ 2

All calculations and statistics were performed usingMicrosoft Excel (Microsoft Corporation: Redmond, WA).

Treatment protocol

Treatment protocol was participation in a SPWC/H. RTWrehabilitation programs generally fall into two categories:WH and WH. WH-based systems rely heavily on activities

Fig. 1. First (pre) and last (post) week sports performance-based work

hardening and conditioning (SPWC/H) program lifting abilities of all 55

patients grouped. Average volume measure (6standard deviation) of one

set of each the deadlift (top left) and the overhead lift (bottom left) in-

creased after a SPWC/H program. Predicted one repetition maximum

(1 RM; 6standard deviation) for each deadlift (top right) and overhead lift

(bottom right) also increased after the program intervention. *Significance

of p!0.0001.

42 K. Cole et al. / The Spine Journal 9 (2009) 39–46

that simulate the job environment, whereas WC generallyrelies on exercises isolating specific muscles to restorestrength and physical function. The rehabilitation programused for this study is a combination of the two concepts,relying more on the WC system. Although the rehabilitationprotocols involve work-specific type tasks, progression ofactivities are based on the strength and conditioning princi-ples of the National Strength and Conditioning Association[22–24]. This progression involves the fundamental theoryof periodization in resistance training volume and intensity.For resistance training volume, increase is achieved throughaddition of repetitive submaximal loading through increasesin weight and sets in the 8 to 15 repetition range; alternatingbody part and task focus throughout the 5 days/wk program.Sessions focused on aerobic conditioning, flexibility, corestabilization, intense functional strength training with freeweights, and functional tasks. The daily training volumes(sets� repetition� load) was progressed using sportsperformance principles.

Statistical analysis

A one-way ANOVA was used to individually analyze therelationship between each of Deadlift and Overhead liftweights among PDL classification. The ANOVA test was alsoused to determine the relationship between single or multiplefusion and PDL. A Fisher’s exact test was used for post hocanalysis to determine differences between individual groups.To detect a significant difference between the pooled compar-isons for the deadlifts and overhead lifts were determined bya Student’s t-test because of narrowing to only two groups ofcomparison. The level of significance was set at p!0.05. Nu-merical data are presented as mean6SD.

Results

Pre- and postvolume and one repetition maximum

All subjects demonstrated a significant increase in volumeand predicted one repetition maximum (1 RM) for each ofdeadlift (DLv, DLm) and overhead lift (OHv, OHm). DLv in-creased from 331.96203.3 to 1083.96563.3 (p!0.0001) andDLm from 38.1621.5 to 132.3658.0 (p!0.0001). The OHvincreased from 336.26166.8 to 778.06273.8 (p!0.0001);OHm from 39.5618.2 to 96.8630.6 (p!0.0001; Fig. 1).

When comparing pre- and post-DLv, DLm, OHv, andOHm by PDL after completion of the SPWC/H program,ANOVA analysis revealed significant difference betweengroups. Post hoc analysis, however, revealed that significantdifferences did not exist between each adjacent group(pO0.05). On further inspection of the data in each classi-fication, it was observed that lifting values tended to resttoward the transition points for each group reducing thepower of the difference between adjacent groups. Giventhe inherent ranked order of the classification and the exis-tence of an overall statistical difference; adjacent groups

are merged a posteriori. Thus, VH and heavy groups, themedium and medium heavy (MH) groups, and the lightand very light groups were merged (H/VH, M/MH, andL/VL). Statistical analysis did reveal significant differencesfor each of the pre- and postconditions for each deadlift andoverhead measures between new groupings (pre-DLm,p50.0082; post-DLm p!0.0001; pre5DLv, p!0.0084;post-DLv, p!0.0001; pre-OHv, p50.002; post-OHv,p50.03896; pre-OHm, p50.002; post-OHm, p50.000662).

After subjects were grouped into each category by PDLgroups, it was then determined that there still existed a sig-nificant difference between pre and post values for each ofthe outcome measures of DLv, DLm, OHv, and OHm (allhaving p!0.0001; Fig. 2)

Analysis of pre-physical demand level-based outcomes

Outcomes of PDL classification were also analyzedbased on grouping each patient by their first week PDL(pre-PDL) classification. Patients fell into three pre-PDLclassifications: light (n541, 75.9%), LM (6, 11.1%), andmedium (7, 13.0%). Of those who started at the mediumlevel (the highest PDL level any patient entered), all indi-viduals finished at the VH level. Of those who started atthe LM classification, half the population ended at eachthe VH and medium/heavy levels. The lowest level ofentering PDL had the largest number of subjects and thegreatest distribution. Ten patients (24.4%) from the pre-PDL light completed at VH; 5 (12.2%) at heavy; 16(39%) at MH; 7 (17%) at medium, and 2 (4.9%) at LM,

Fig. 2. First (pre) and last (post) week sports performance-based work

hardening and conditioning program lifting abilities of patients when sep-

arated into PDL groupings of medium and medium/heavy (M/MH, light

gray); and heavy and very heavy (H/VH, black). Volume of one set of

a deadlift (top left) and overhead lift (bottom left) are shown (average6s-

tandard deviation). Predicted one repetition maximum (1 RM) is also pro-

vided (average6standard deviation bars) for deadlift (top right) and

overhead lift (bottom right). *Significant increase between pre- and post-

states of each group (p!0.0001). zSignificant difference between PDL

groupings (p!0.05).

43K. Cole et al. / The Spine Journal 9 (2009) 39–46

and only 1 (2.4%) at the light level (Fig. 3). Interestingly,the mode increase in PDL for all groups was by threelevels, where ranks of each group are defined as L50,LM51, M52, MH53, H54, VH55.

ANOVA analysis of postdeadlift volume indicatesa significant difference between groups when grouped bypre-PDL classifications (p!.0001). Post hoc statistics,

Fig. 3. Subjects were grouped by their starting PDL, with subjects only

starting in the light (L, light gray, first row), light/medium (LM, medium

gray, second row) and medium (M, black, third row) classifications. This

graph visualizes the percentage of patients who achieved each of the

PDL levels based on their starting PDL. PDL after program are light

(L), light/medium (LM), medium (M), medium heavy (MH), heavy (H),

and very heavy (VH).

however, reveal no significant difference between the lightand LM (p50.291) and the LM, and medium (p50.179),however, a statistical difference does exist for outcomesbetween the light and medium conditions (p50.015).

Analysis of multiple- vs. single-level fusion

Each subject was classified into a single-level fusion, ora multiple-level fusion depending on their operation. Statis-tical analyses then were used to determine the differencebetween their final lifting values. No significant differencefor end DLvol (p50.843), DLm (p50.736), OHv(p50.773), and OHm (p50.737; Fig. 4)

Overall outcomes

Out of 55 individuals, 41 (75.9%) started at the light clas-sification, 6 (11.1%) at the LM, and 7 (13.0%) at the mediumclassification. After the SPWC/H intervention, only 1 patient(1.9%) remained at light, 2 (3.7%) at the LM, 7 (13%) atmedium, 19 (35.2%) at medium/heavy, 5 (9.3%) at Heavy,and 20 persons (37%) at the heavy PDL (Fig. 5). This alsocan be broken down into 100% of patients starting ata PDL of medium or below, whereas after intervention,81.5% were at the medium/heavy PDL or above.

Discussion

Although the main outcome measure of the success oflumbar fusion, WH, WC, and workers’ compensationprograms is RTW status, few studies have related RTW

Fig. 4. Final week lifting measures were analyzed for single (black) and

multiple (gray) levels of spinal segments fused during surgery. No differ-

ence was found between (Top) single and multiple levels of fusion for

overhead and deadlift volume and (Bottom) overhead and deadlift pre-

dicted one repetition maximum where bar graph values are average values

of each group with standard deviation bars.

Fig. 5. Number of all patients at each physical demand level (PDL) at the

start of the program (pre; white; first row) and after completing the pro-

gram (post; black; back row). PDL categories are light (L), light/medium

(LM), medium (M), medium/heavy (MH), heavy (H) and very heavy (VH).

Notice all patients preprogram are in the medium and below category,

whereas postprogram the vast majority of patients achieved the medium

and above classification.

44 K. Cole et al. / The Spine Journal 9 (2009) 39–46

outcomes to PDL, nor described the ability of a WC/Hprogram to increase strength or PDL classification as anoutcome variable. Not normalizing for functional demandlevel achieved by the patient related to the PDL of theiroccupation, may account for decreased RTW reports andpost-RTW re-injury rates. It is first important to determinewhether a WC program is indeed able to increase functionalstrength in a manner comparable with job duty.

Initial physical demand level classification

This study identified that on discharge from traditionalphysical therapy, PDL classifications (pre-PDL) were low.All patients were classified under a pre-PDL of belowmedium, with over three quarters starting at the lowest clas-sification of light (less than 20 lb occasionally). Low physicalfunction after spinal fusion and traditional physical therapymay be multifactorial. It has been reported that time off workbetween initial injury and lumbar fusion surgery ranges from16.2 and 26.7 months [25,26]. Also, lumbar extensor strengthand muscle mass has also been identified to decrease bystrength testing and imaging at L3–L4 in those having under-gone lumbar fusion compared with exercise and educationcontrols [27]. Factors such as these may contribute to decon-ditioning, decreased strength and resulting decreased func-tional strength (PDL) in patients after fusion surgery.

Pre- vs. post-physical demand level classification

All subjects in this study demonstrated a significantincrease in deadlift volume (DLv) and one repetitionmaximum (1 RM, DLm). Each subject also demonstratedsignificant increases in overhead lift volume (OHv) and1 RM (OHm). Significant increases in lower extremityand upper extremity strength were also obtained when

grouping by medium/MH and heavy/VH PDL classifica-tions. Many times an expensive, lengthy functional capac-ity assessment/evaluation is performed to determinefunctional strength. PDL classifications, defined by theDOL define occasional lifting as lifting from floor to waist,may be insufficient because of the general involvement ofupper and lower body strength and lifts from floor to waist,waist to waist, and waist to overhead in many heavy andVH PDL work duties. Strength gains demonstrated in bothupper and lower extremities with change in PDL further in-dicates that benchmarks in lifting activities during a rehabil-itation program may be used to rapidly predict functionalabilities.

Analysis of pre-physical demand level classification

Data do suggest that starting PDL classification statusmay have an influence on outcomes. All of the subjectsin the medium PDL classification ended in the VH classifi-cation by the end of the program. Subjects starting in theLM and the light groups, however, varied in resultsalthough 50% of subjects from the LM group finishing atthe VH classification and approximately one quarter ofthose starting at light, finishing at VH, and over half finish-ing at the level of medium/heavy or above.

This may indicate that starting an SPWC/H program ata higher level results in increased chance for success, butin no means indicates a poor outcome if starting at a lowerPDL classification considering over half of those individ-uals finished above the medium PDL. It is also significantto note that all groups had a median increase of threeclassifications, demonstrating significant gain in functionalstrength. This means that most patients will gain significantfunctional strength and potential employability withcompletion of a sports performance-based program.

Single- vs. multiple-level fusions

We were also able to address the effect of number oflevels fused on outcomes. All subjects in this study hadno previous lumbar fusion surgery, thus was not a factorfor decreased outcomes. When controlling for number oflevels fused in our study, there was no effect. Statisticalanalysis revealed that outcome measures of DL volumeand 1 RM as well as Overhead volume and 1 RM werenot significantly different between those with single- andmultiple-level fusions. This indicates that outcomes ofstrength gain are just as favorable for those with singleand those with more than one lumbar level fused.

Physical demand level outcomes

In this study, we were able to demonstrate a significantincrease in strength demonstrated by an increase in PDLlevel classification in all but one patient. On average, eachpatient increased three classifications for PDL. This studydemonstrates that in a SPWC/H program, 37% of patients

45K. Cole et al. / The Spine Journal 9 (2009) 39–46

ended at the VH level (lifting 100 lb occasionally) and81.5% above the medium level (lifting at least 50 lb occa-sionally). This is significant considering 100% of subjectsstarted at a PDL of below medium with the majority(75.9%) beginning from the light classification. Further-more, approximately 85% of the positions described inthe U.S. DOL’s Dictionary of Occupational Titles are atthe medium level or below. With 75.9% of subjects at me-dium or above, this significantly increases possible employ-ability of individuals having participated in an SPWC/Hprogram.

Limitations

One of the most limiting factors of this study is the lackof a control group. A control group is not specifically in-cluded in this study for several reasons. First, other WHstudies analyzing RTW and qualitative measures identifycontrols as subjects who were referred to the program butwere subsequently denied coverage. This system of desig-nating controls may function for retrospective question-naires but does not provide a follow-up strengthassessment, as in the present study, owing to increaseddifficulty of patient follow-up. Furthermore, this studywas conducted under the limitations of the workers’compensation system where treatment is prescribed bythe referring physician, in this study, the surgeon. In allcases, referring physicians are unwilling to decrease poten-tial outcomes for the purpose of a control group.

Every patient who enters the SPWC/H program hasalready undergone an episode of traditional physical ther-apy, after which, the patient’s functional capacity is notdeemed sufficient by the physical therapist, physician,and the case manager/adjuster to return to their previousjob. Although few studies provide strength measurementsof patients after lumbar fusion, some do demonstratea large decrease in strength [27,28]. These documenteddecreases in strength after lumbar fusion, parallel thedecreased functional strength demonstrated by the group’soverall low starting PDL classification. This providessome bases to compare the postintervention increasesin strength with generally accepted low postsurgicalstrengths.

A number of research studies have been aimed at iden-tifying different factors that result in a decreased or pooroutcome after lumbar fusion and a WC/H program.Contributing limiting factors that have been identifiedinclude number of levels fused, reason for surgery, surgi-cal approach, older age at injury, longer time from injuryto fusion, increased time on work disability before fusion,increased number of low back operations, perceiveddisability, depressive symptoms, patient overall assess-ment, undergoing litigation, work status at time of surgery,and smoking [21,29–32]. Many of these factors are aimedat identifying those who were not successful in completinga WH/C program or that had poor outcomes. This study is

biased toward individuals who were able to complete anSPWC/H, and thus may not share similar complicatingfactors, limiting the generalizability of this study. It wasnot the purpose of this study to identify factors of whypatients did or did not increase in strength more thananother, nor to identify which surgical proceduresand for what diagnoses the program is effective. Datashow that patients entering an SPWC/H program afterlumbar fusion with appropriate motivation do indeedgain functional strength by meeting a heavier job classifi-cation lift. Future investigation combined with qualitativeassessments may be performed to identify if similar differ-ences exist between varying levels of success in sucha program.

RTW status is a common outcome used to measuresuccess in workers’ compensation interventions such asWC and WH programs. This study did not determine RTW,but functional strength to determine whether patient hadthe ability to return to a job of varying PDL classifications.Future studies should be aimed at determining whether in-creases in measured PDL indeed correlates with increasedRTW and the possibility of reduced re-injury rate givenmatching PDL obtained after an SPWC/H program and thejob to which the patient is returning.

Conclusions

Post-lumbar spinal fusion patients are typically at thelight PDL classification (20 lb occasionally) or below oncompletion of traditional physical therapy program. Thisstudy demonstrated after an SPWC/H program, personshaving had lumbar fusion significantly increase magnitudeof deadlift and overhead lift volume and one repetitionmaximum. Both upper and lower extremity measures pre-dicted increases in classification of PDL. Our data suggestthat there may be an interaction between functional gainsand starting PDL, although each starting PDL group dem-onstrated a median increase in three PDL classificationsas defined by the US DOL. We were also able to determinethat there was no difference in strength outcome betweenthose with a single- vs. multiple-level fusion surgery.

Although the vast majority of individuals entered theprogram at the lowest PDL classification (20 lb or lessoccasionally), more than 80% of patients completed theprogram at PDL of medium (50 lb occasionally) or above,and 37% of patients achieved the maximum PDL (above100 lb occasionally). Future studies are needed to deter-mine if increases in strength determined by PDL classifica-tion such as these relate to increased RTW rates anddecreased re-injury rates.

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