Research Report
Trunk Kinematics During Locomotor Activities
We invesrigated upper-body (ie, trunk) angular kinematics (motions) during gait, stair climbing and descending, and nking from a chair in two referrneeframerelative to the pelvb and to room coordinates. Bilateral kinematic data were collectedfrom I I healthy subjects (6female, 5 mumale), who were 27 to 88 years of age (X=58.9, SD=I7.9). During stair climbing, maximum trunkjlmon relative to the room was at least double that during stair descending and gait. Anking from a chair required the most trunkjlm'on/sctension range of motion (ROW but the least abduction/adduction and medial/lateral (internul/acternu~totation. Trunk ROM during gait was small (1112") and consktent with previous literature. Trunk range of motion relative to the room during stair climbing and descending was p a t e r tban trunk ROM during gait in all planes. The pelvis and trunk rotate in the transverseplane in greater synchrony during stair descending (Z=8.1°, SD=5.6") than during gait (Z=l2.0", SD=4.2"). For all activities, trunk frontal and sagiral ROM relative to the pelub was greater than that relative to the room coordinates. 7hbJnding suggests that trunk/plvb coordination may be used to reduce potentially destabilizing anti-gravity trunk motions during daily actiuities. We conclude that upper-body kinematics relative to both pelub and gravity during daily activities are important to locomotor control and should be com'dered infuture studies of patients with locomotor disabilities. /&bs DE, Wong D, Jevsevar D, et al. Trunk kinematics during locomotor activities. Phys Ther. 1992;72505-514.1
David E Krebs Dennls Wong David Jevsevar Patrlck 0 Riley W Andrew Hodge
Key Words: Gait, Kinematics, Locomotion, Spinal mobility impairment.
Trunk kinematics are critically important to the maintenance of body equi-
librium and should be examined as a component of locomotion analysis.l.2
DE Krebs, PhD, PT, is Associate Professor, MGH Institute of Health Professions, 15 River St, Boston, MA 02108-3402 CUSA). Address all corresmndence to Dr Krebs. \
r
D Wong, MD, PT, is Resident in Rehabilitation Medicine, Kingsbrook Jewish Medical Center, 585 Schenectadv Ave, Brooklyn, NY 11203. He was an NIDRR Advanced Rehabilitation Fellow at the MGWMIT Rehab Engineering Center when this work was conducted. D Jevsevar, MD, is Resident in Onhopaedics, Tuhs New England Medical Center, 750 Washington St, Boston, M ' A 02111. He was an NIDRR Advanced Rehabilitation Fellow at the MGWMIT Rehab Engineering Center when this work was conducted. PO Riley, PhD, is Technical Director, MGH Biomotion Iaboratory, Massachusetts General Hospital, Boston, MA 02114. WA Hodge, MD, is Assistant in Onhopaedics, Massachusetts General Hospital. This study was approved by the Massachusetts General Hospital Institutional Review Board. This work was supponed in pan by Grants H133P90005 and H133G00025 from the National Institute of Disability and Rehabilitation Research.
Three-dimensional, normal trunk kinematic data obtained during stair and chair locomotor daily activities, as well as during gait, enable therapists to make comparisons with pathological locomotion characteristics such as "gluteus medius" limp following hip surgery, trunk abduction lurch associated with knee arthroplasty or aboveknee amputation, and spinal fusion. To date, however, most locomotor studies have only described lowerextremity kinematics.- Comparatively little information exists on the kinematics of upper-body movement during gait, and no three-dimensional kinematic data have been reported for other locomotor activities of daily living such as stair and chair activities.9
nix article was submitted June 92, 1991, and was accepted Manb 18, 1992.
Physical Therapyll'olume 72, Number 7/July 1992
505 / 35
-
Table 1. Subject Characteristics and Locomotor Activities in Which Subjects' Data Are Includeda Locomotor Activity Subject No.
sex
Age(y)
Height (cm)
Weight (kg)
Free GaR (n=8)
Paced Gait (n=8)
Stair Climbing (n=11)
Stalr Descendlng (n=lO)
Rising from a Chair (n=11)
1 2
3 4
5
6 7
8 9 10 11
x SD
Range "Data from subjects 5, 6, and 7 are not included in some analyses because of technical limitations (eg, incomplete visibility while the subject was in the viewing volume).
In the 1960s, Murray and colleagues7z8 described the transverse (mediaatera1 [intemaVextemal])rotation of the trunk for free-speed walking of 60 healthy men (20-65 years of age) to be 6.92 1.9 degrees @+SD). Recently, Opila-Correialo reported threedimensional trunk kinematics observed during the free-speed gait of 14 women, 21 to 54 years of age @=35.0, SD=10.4). In gait trials with subjects wearing low-heeled footwear, trunk flexiodextension, abductiod adduction, and mediaVlateral total angular excursions relative to the pelvis averaged 11.1,12.6, and 17.5 degrees, respectively. These same displacements relative to room coordinates were 9.2, 5.2, and 11.2 degrees, respectively. Treadmill gait was studied by Thorstensson et all1 and Stokes et a1.12Although Thorstensson et a1 did not report transverse-plane rotation, they did report net frontal-plane trunk range of motion (ROM) in 7 healthy 18- to 34-year-old subjects to be 2 to 9 degrees and net flexiodextension ROM to be 2 to 12 degrees in walking. Stokes and colleagues analyzed 36 1506
trunk movement of 3 female and 5 male subjects during treadmill walking (with shoes on) and reported "small" flexiodextension amplitudes, with a mean trunk abductiodadduction of 4.921.8 degrees and a mean transverse-plane trunk rotation of 4.7k1.6 degrees. It is clear that free walking differs from treadmill gait13 and that room-referenced trunk kinematics differ from pelvis-referenced kinematics. Because the locomotor control system, using sensory input from the vestibular system, is aware of global, gravity-referenced coordinates, we examined both selfreferenced (pelvis-referenced) and gravity-referenced (room-referenced) trunk motions during locomotor activities of daily living. The purposes of our study were (1) to determine a sample of trunk ROM and maximum angular orientation in flexiodextension, abductiod adduction, and mediaVlateral rotation in healthy subjects during daily activities, including free-speed and paced gait, during stair climbing and descending, and while rising from a
chair and (2) to examine these kinematic findings in two frames of reference-the trunk relative to the pelvis and the trunk relative to room (gravity) coordinates.
Eleven volunteers who were free of musculoskeletal and neurological disease participated in the study. Subjects were recruited from the community and the laboratory staff. All subjects, to be eligible for the study, must have been (1) able to walk at least 1.6 km (1 mile) without stopping and to climb and descend stairs and arise from a chair without personal o r upper-extremity assistance and (2) free of neuro-musculo-skeletal pathology and deformity as determined by history and physical examination. All subjects provided written informed consent. Participants' ages, sex, heights, and weights are presented in Table 1.
Physical Therapyllrolume 72, Number 7/July 1992
Micro VAX I I a
Figure 1. schemutic depiction of laboratory kinemutic data-acquisitionapparatus. The PDP 11/60 and MicroVAX II@ computers are used for data processing as well as acqukition. Instrumentation Gait trials were conducted on a 10-m walkway. Stair trials involved the use of a weighted modular staircase with four stairs. The first of the four steps was 2.5 cm tall and was provided merely to help initiate steady-state stepping activity prior to data collection on three 18-x28-cm stairs. Chair trials involved the use of an armless and backless chair with an adjustableheight rigid seat. Four Selspot I1 optoelectric cameras,* in addition to PDP ll/bOt and MicroVAX II@ computers, were used to acquire bilateral kinematic data from the subjects. The Selspot system's infrared light-emitting diodes (LEDs) are tracked by an infrared detector within each camera; the system accuracy is < 3 mm.l4 Camera placement resulted in a viewing volume of 1.8 m per side (Fig. 1). Kinematic data were acquired for 3 seconds at 153 Hz.
The LEDs were mounted in rigid arrays secured to 11body segments: head, trunk, pelvis, thighs, shanks, feet, and upper arms (Fig. 2). Each segment was modeled as a rigid body having 6 degrees of freedom (three translations and three rotations), with its kinematics determined in part using TRACKo software*14 and the technique described by Riley et al.15 The orientation of each body segment in space and the associated joint angles were calculated using 3-1-2 Cardan angles.1 6 r 1 7
Procedure General. Barefoot subjects performed all activities in a single session. To prevent the preferred cadence from being influenced by the paced cadence, free (preferred-speed) gait was followed by paced gait. Stair climbing, then stair descending, then arising from a chair were performed with at least 1.5 minutes' rest between trials.
'Selspot AB, Flojelbergsgatan 14, S-431 37 Molndal, Sweden, and Selspot System Ltd, Troy, MI 48093. 'Digital Equipment Corp, 146 Main St, Maynard, MA 01754.
evel loped at the Massachusetts Institute of Technology, Cambridge, Mass.
Physical TherapyNolume 72, Number 7/July 1992
To approximate easily reproduced natural cadences and to prevent velocity-dependent kinematic changes from confounding the within- and between-subject comparisons, the paced cadence chosen for each activity was determined from pilot studies and previous All activities, except rising from a chair, were performed with unrestricted arm-swing.
Free gait. Subjects walked along a 10-m walkway at a comfortable speed; that is, subjects were instructed to "walk the way you usually do, as if you were t a h g a brisk stroll in the park." At least three strides were completed before the subjects entered the data-collection portion of the walkway. Several acclimation trials were completed before two trials of data were collected. Paced gait Subjects walked using an identical procedure to that of free gait, but each foot-strike was synchronized with a metronome set at 120 beats per minute (bpm). Subjects practiced this paced gait cadence until synchrony was comfortably achieved for each step, as determined by the heel-strike occurring at each metronome beat, without awkwardappearing "marching." Stair climbing. Subjects climbed stairs to the beat of the metronome set at 80 bpm, with the left foot first striking the small step and the right foot striking the next fill riser. S u b jects stopped when they reached the top platform, which was the fourth step. Several practice trials were performed before the two datacollection trials to ensure smoothness and cadence synchronization with the metronome. Descending stalrs. Subjects started on the fourth (top) step and descended in time with the beat of a metronome set at 80 bpm and with the left foot striking the third step. Several practice trials preceded two datacollection trials, again to ensure smoothness and synchronization with the metronome.
were determined from center-of-mass (CM) displacements in this same "window." Means, standard deviations, and repeated-measures multivariate analysis of variance (MANOVA) results were calculated with the Statistical Analysis System (version 6.03)~for the IBM PC.II Multivariate statistics for multiple dependent variables were used to preserve the experimentwise alpha level at .10) in any activity. Trunk ROM during rising from a chair in all planes relative to either the pelvis or room coordinates was significantly different from stair and gait ROM (Hotelling-LawleyF>70.1, Pc.01) with the exception of chair versus gait abduction/adduction (F=.18, P=.68). Gait trunk ROM was similar (Fc5.6, P>.05) to stairdescending trunk ROM in all planes, but gait ROM differed significantly from stair-climbing ROM in all planes (F> 10.7,PC.O1). Trunk ROM did not differ significantly between stair climbing and descending, except in mediaatera1 rotation (F= 11.5, P=.Ol).
$SAS lnstitute Inc, PO Box 8000, Cary, NC 27511.
"International Business Machines Corp, PO Box 1328, Boca Raton, EL 33432.
38 / 508
Physical TherapyNolume 72, Number 74uly 1992
ture (segment anatomical orientations), which varies across subjects, and on movement amplitude. Range of motion depends only on movement peak-to-peak amplitude. For example, subjects could attain 36 degrees of trunk flexion ROM during rising from a chair by an excursion from 10 degrees of extension to 26 degrees of flexion, o r 5 degrees of flexion to 41 degrees of flexion.
Kinematic Patterns loo%
KNEE HEIGHT
Figure 3. Initial position for rising from a chair (left) and knee height detemzination landmarks ((right). The greatest trunk ROM relative to the pelvis occurred for flexion/extension during rising from a chair (22.9"?9.5")and was quadruple that of gait sagittal ROM (Fig. 5A). Roomreferenced flexion/extension during rising from a chair (36.2Ok7.7") exceeded by >50% (F= 19.8,P < ,001) that relative to the pelvis (Fig. 5B). Nonsagittal trunk ROM relative to the pelvis was greatest in stair climbing (abductiodadduction, 14.Pk5.P) and least in rising from a chair (medial/ lateral rotation, 3.2"kl.l")Fig. 5A). Indeed, trunk ROM relative to the pelvis was greater than that relative to the room coordinates across all activities and motions (F> 5.3, P < .05), except in chair and stair medialflatera] rotation (Figs. 5A and 5B). During gait, trunk maximum sagittal orientation was about 3 degrees more toward extension relative to the pelvis (Fig. 6A) than relative to the room coordinates (Fig. 6B); this difference was not significant. Maximum trunk flexion relative to the room coordinates (Fig. 6B) during stair climbing was double that recorded during stair descending and sextuple that recorded during gait (F> 15.3, P
Trunk Kinematics During Locomotor Activities
We invesrigated upper-body (ie, trunk) angular kinematics (motions) during gait, stair climbing and descending, and nking from a chair in two referrneeframerelative to the pelvb and to room coordinates. Bilateral kinematic data were collectedfrom I I healthy subjects (6female, 5 mumale), who were 27 to 88 years of age (X=58.9, SD=I7.9). During stair climbing, maximum trunkjlmon relative to the room was at least double that during stair descending and gait. Anking from a chair required the most trunkjlm'on/sctension range of motion (ROW but the least abduction/adduction and medial/lateral (internul/acternu~totation. Trunk ROM during gait was small (1112") and consktent with previous literature. Trunk range of motion relative to the room during stair climbing and descending was p a t e r tban trunk ROM during gait in all planes. The pelvis and trunk rotate in the transverseplane in greater synchrony during stair descending (Z=8.1°, SD=5.6") than during gait (Z=l2.0", SD=4.2"). For all activities, trunk frontal and sagiral ROM relative to the pelub was greater than that relative to the room coordinates. 7hbJnding suggests that trunk/plvb coordination may be used to reduce potentially destabilizing anti-gravity trunk motions during daily actiuities. We conclude that upper-body kinematics relative to both pelub and gravity during daily activities are important to locomotor control and should be com'dered infuture studies of patients with locomotor disabilities. /&bs DE, Wong D, Jevsevar D, et al. Trunk kinematics during locomotor activities. Phys Ther. 1992;72505-514.1
David E Krebs Dennls Wong David Jevsevar Patrlck 0 Riley W Andrew Hodge
Key Words: Gait, Kinematics, Locomotion, Spinal mobility impairment.
Trunk kinematics are critically important to the maintenance of body equi-
librium and should be examined as a component of locomotion analysis.l.2
DE Krebs, PhD, PT, is Associate Professor, MGH Institute of Health Professions, 15 River St, Boston, MA 02108-3402 CUSA). Address all corresmndence to Dr Krebs. \
r
D Wong, MD, PT, is Resident in Rehabilitation Medicine, Kingsbrook Jewish Medical Center, 585 Schenectadv Ave, Brooklyn, NY 11203. He was an NIDRR Advanced Rehabilitation Fellow at the MGWMIT Rehab Engineering Center when this work was conducted. D Jevsevar, MD, is Resident in Onhopaedics, Tuhs New England Medical Center, 750 Washington St, Boston, M ' A 02111. He was an NIDRR Advanced Rehabilitation Fellow at the MGWMIT Rehab Engineering Center when this work was conducted. PO Riley, PhD, is Technical Director, MGH Biomotion Iaboratory, Massachusetts General Hospital, Boston, MA 02114. WA Hodge, MD, is Assistant in Onhopaedics, Massachusetts General Hospital. This study was approved by the Massachusetts General Hospital Institutional Review Board. This work was supponed in pan by Grants H133P90005 and H133G00025 from the National Institute of Disability and Rehabilitation Research.
Three-dimensional, normal trunk kinematic data obtained during stair and chair locomotor daily activities, as well as during gait, enable therapists to make comparisons with pathological locomotion characteristics such as "gluteus medius" limp following hip surgery, trunk abduction lurch associated with knee arthroplasty or aboveknee amputation, and spinal fusion. To date, however, most locomotor studies have only described lowerextremity kinematics.- Comparatively little information exists on the kinematics of upper-body movement during gait, and no three-dimensional kinematic data have been reported for other locomotor activities of daily living such as stair and chair activities.9
nix article was submitted June 92, 1991, and was accepted Manb 18, 1992.
Physical Therapyll'olume 72, Number 7/July 1992
505 / 35
-
Table 1. Subject Characteristics and Locomotor Activities in Which Subjects' Data Are Includeda Locomotor Activity Subject No.
sex
Age(y)
Height (cm)
Weight (kg)
Free GaR (n=8)
Paced Gait (n=8)
Stair Climbing (n=11)
Stalr Descendlng (n=lO)
Rising from a Chair (n=11)
1 2
3 4
5
6 7
8 9 10 11
x SD
Range "Data from subjects 5, 6, and 7 are not included in some analyses because of technical limitations (eg, incomplete visibility while the subject was in the viewing volume).
In the 1960s, Murray and colleagues7z8 described the transverse (mediaatera1 [intemaVextemal])rotation of the trunk for free-speed walking of 60 healthy men (20-65 years of age) to be 6.92 1.9 degrees @+SD). Recently, Opila-Correialo reported threedimensional trunk kinematics observed during the free-speed gait of 14 women, 21 to 54 years of age @=35.0, SD=10.4). In gait trials with subjects wearing low-heeled footwear, trunk flexiodextension, abductiod adduction, and mediaVlateral total angular excursions relative to the pelvis averaged 11.1,12.6, and 17.5 degrees, respectively. These same displacements relative to room coordinates were 9.2, 5.2, and 11.2 degrees, respectively. Treadmill gait was studied by Thorstensson et all1 and Stokes et a1.12Although Thorstensson et a1 did not report transverse-plane rotation, they did report net frontal-plane trunk range of motion (ROM) in 7 healthy 18- to 34-year-old subjects to be 2 to 9 degrees and net flexiodextension ROM to be 2 to 12 degrees in walking. Stokes and colleagues analyzed 36 1506
trunk movement of 3 female and 5 male subjects during treadmill walking (with shoes on) and reported "small" flexiodextension amplitudes, with a mean trunk abductiodadduction of 4.921.8 degrees and a mean transverse-plane trunk rotation of 4.7k1.6 degrees. It is clear that free walking differs from treadmill gait13 and that room-referenced trunk kinematics differ from pelvis-referenced kinematics. Because the locomotor control system, using sensory input from the vestibular system, is aware of global, gravity-referenced coordinates, we examined both selfreferenced (pelvis-referenced) and gravity-referenced (room-referenced) trunk motions during locomotor activities of daily living. The purposes of our study were (1) to determine a sample of trunk ROM and maximum angular orientation in flexiodextension, abductiod adduction, and mediaVlateral rotation in healthy subjects during daily activities, including free-speed and paced gait, during stair climbing and descending, and while rising from a
chair and (2) to examine these kinematic findings in two frames of reference-the trunk relative to the pelvis and the trunk relative to room (gravity) coordinates.
Eleven volunteers who were free of musculoskeletal and neurological disease participated in the study. Subjects were recruited from the community and the laboratory staff. All subjects, to be eligible for the study, must have been (1) able to walk at least 1.6 km (1 mile) without stopping and to climb and descend stairs and arise from a chair without personal o r upper-extremity assistance and (2) free of neuro-musculo-skeletal pathology and deformity as determined by history and physical examination. All subjects provided written informed consent. Participants' ages, sex, heights, and weights are presented in Table 1.
Physical Therapyllrolume 72, Number 7/July 1992
Micro VAX I I a
Figure 1. schemutic depiction of laboratory kinemutic data-acquisitionapparatus. The PDP 11/60 and MicroVAX II@ computers are used for data processing as well as acqukition. Instrumentation Gait trials were conducted on a 10-m walkway. Stair trials involved the use of a weighted modular staircase with four stairs. The first of the four steps was 2.5 cm tall and was provided merely to help initiate steady-state stepping activity prior to data collection on three 18-x28-cm stairs. Chair trials involved the use of an armless and backless chair with an adjustableheight rigid seat. Four Selspot I1 optoelectric cameras,* in addition to PDP ll/bOt and MicroVAX II@ computers, were used to acquire bilateral kinematic data from the subjects. The Selspot system's infrared light-emitting diodes (LEDs) are tracked by an infrared detector within each camera; the system accuracy is < 3 mm.l4 Camera placement resulted in a viewing volume of 1.8 m per side (Fig. 1). Kinematic data were acquired for 3 seconds at 153 Hz.
The LEDs were mounted in rigid arrays secured to 11body segments: head, trunk, pelvis, thighs, shanks, feet, and upper arms (Fig. 2). Each segment was modeled as a rigid body having 6 degrees of freedom (three translations and three rotations), with its kinematics determined in part using TRACKo software*14 and the technique described by Riley et al.15 The orientation of each body segment in space and the associated joint angles were calculated using 3-1-2 Cardan angles.1 6 r 1 7
Procedure General. Barefoot subjects performed all activities in a single session. To prevent the preferred cadence from being influenced by the paced cadence, free (preferred-speed) gait was followed by paced gait. Stair climbing, then stair descending, then arising from a chair were performed with at least 1.5 minutes' rest between trials.
'Selspot AB, Flojelbergsgatan 14, S-431 37 Molndal, Sweden, and Selspot System Ltd, Troy, MI 48093. 'Digital Equipment Corp, 146 Main St, Maynard, MA 01754.
evel loped at the Massachusetts Institute of Technology, Cambridge, Mass.
Physical TherapyNolume 72, Number 7/July 1992
To approximate easily reproduced natural cadences and to prevent velocity-dependent kinematic changes from confounding the within- and between-subject comparisons, the paced cadence chosen for each activity was determined from pilot studies and previous All activities, except rising from a chair, were performed with unrestricted arm-swing.
Free gait. Subjects walked along a 10-m walkway at a comfortable speed; that is, subjects were instructed to "walk the way you usually do, as if you were t a h g a brisk stroll in the park." At least three strides were completed before the subjects entered the data-collection portion of the walkway. Several acclimation trials were completed before two trials of data were collected. Paced gait Subjects walked using an identical procedure to that of free gait, but each foot-strike was synchronized with a metronome set at 120 beats per minute (bpm). Subjects practiced this paced gait cadence until synchrony was comfortably achieved for each step, as determined by the heel-strike occurring at each metronome beat, without awkwardappearing "marching." Stair climbing. Subjects climbed stairs to the beat of the metronome set at 80 bpm, with the left foot first striking the small step and the right foot striking the next fill riser. S u b jects stopped when they reached the top platform, which was the fourth step. Several practice trials were performed before the two datacollection trials to ensure smoothness and cadence synchronization with the metronome. Descending stalrs. Subjects started on the fourth (top) step and descended in time with the beat of a metronome set at 80 bpm and with the left foot striking the third step. Several practice trials preceded two datacollection trials, again to ensure smoothness and synchronization with the metronome.
were determined from center-of-mass (CM) displacements in this same "window." Means, standard deviations, and repeated-measures multivariate analysis of variance (MANOVA) results were calculated with the Statistical Analysis System (version 6.03)~for the IBM PC.II Multivariate statistics for multiple dependent variables were used to preserve the experimentwise alpha level at .10) in any activity. Trunk ROM during rising from a chair in all planes relative to either the pelvis or room coordinates was significantly different from stair and gait ROM (Hotelling-LawleyF>70.1, Pc.01) with the exception of chair versus gait abduction/adduction (F=.18, P=.68). Gait trunk ROM was similar (Fc5.6, P>.05) to stairdescending trunk ROM in all planes, but gait ROM differed significantly from stair-climbing ROM in all planes (F> 10.7,PC.O1). Trunk ROM did not differ significantly between stair climbing and descending, except in mediaatera1 rotation (F= 11.5, P=.Ol).
$SAS lnstitute Inc, PO Box 8000, Cary, NC 27511.
"International Business Machines Corp, PO Box 1328, Boca Raton, EL 33432.
38 / 508
Physical TherapyNolume 72, Number 74uly 1992
ture (segment anatomical orientations), which varies across subjects, and on movement amplitude. Range of motion depends only on movement peak-to-peak amplitude. For example, subjects could attain 36 degrees of trunk flexion ROM during rising from a chair by an excursion from 10 degrees of extension to 26 degrees of flexion, o r 5 degrees of flexion to 41 degrees of flexion.
Kinematic Patterns loo%
KNEE HEIGHT
Figure 3. Initial position for rising from a chair (left) and knee height detemzination landmarks ((right). The greatest trunk ROM relative to the pelvis occurred for flexion/extension during rising from a chair (22.9"?9.5")and was quadruple that of gait sagittal ROM (Fig. 5A). Roomreferenced flexion/extension during rising from a chair (36.2Ok7.7") exceeded by >50% (F= 19.8,P < ,001) that relative to the pelvis (Fig. 5B). Nonsagittal trunk ROM relative to the pelvis was greatest in stair climbing (abductiodadduction, 14.Pk5.P) and least in rising from a chair (medial/ lateral rotation, 3.2"kl.l")Fig. 5A). Indeed, trunk ROM relative to the pelvis was greater than that relative to the room coordinates across all activities and motions (F> 5.3, P < .05), except in chair and stair medialflatera] rotation (Figs. 5A and 5B). During gait, trunk maximum sagittal orientation was about 3 degrees more toward extension relative to the pelvis (Fig. 6A) than relative to the room coordinates (Fig. 6B); this difference was not significant. Maximum trunk flexion relative to the room coordinates (Fig. 6B) during stair climbing was double that recorded during stair descending and sextuple that recorded during gait (F> 15.3, P
