Determinants of the sit-to-stand movement: a review. (Research Report).

The sit-to-stand (STS) movement is one function people frequently use as they change from a sitting position to a standing position (and then often to walking). The ability to go from a sitting position to a standing position is an important skill; in elderly people, the inability to perform this basic skill can lead to institutionalization, impaired functioning and mobility in activities of daily living (ADL), and even death. (1-3) Changes in ability to perform the STS movement are found in elderly people and people with disabling diseases and are related to the determinants of the STS movement. (4-17) In a survey of independently living Dutch men and women aged 55 years and older, 25% of the men reported moderate disability and 5% of the men reported severe disability (as compared with 37.4% and 7.8% of the women, respectively) on the rising component of the Health Assessment Questionnaire. (1)

The manner in which the STS movement is defined depends to some extent on the aim of the study. Roebroeck et al, (18) for example, defined the STS movement as moving the body's center of mass upward from a sitting position to a standing position without losing balance. Vander Linden et al (19) defined the STS movement as a transitional movement to the upright posture requiring movement of the center of mass from a stable position to a less stable position over extended lower extremities. The STS movement also can be described using kinematic or kinetic variables, with definitions supplied for phases and events during this movement. (20-22) A definition of these phases that is used frequently is the one provided by Schenkman et al (21) and is marked by 4 events. Phase I (flexion-momentum phase) starts with initiation of the movement and ends just before the buttocks are lifted from the seat of the chair. Phase II (momentum-transfer phase) begins as the buttocks are lifted and ends when maximal ankle dorsiflexion is achieved. Phase III (extension phase) is initiated just after maximum ankle dorsiflexion and ends when the hips first cease to extend; including leg and trunk extension. Phase IV (stabilization phase) begins after hip extension is reached and ends when all motion associated with stabilization is completed. (21)

Studying the STS movement, in our opinion, requires a basic knowledge of the factors influencing how the movement is performed. The determinants, we believe, should be independent from the techniques used to study movement. The extent of these determinants' influence can be small and detected only when using specific measurement or research techniques (eg, moments assessed by force plates). Knowledge of the determinants, we contend, is necessary in order to conduct research on the STS movement or to interpret results of reported studies, because the results can be, in part, a function of a determinant.

The STS movement has been studied using standardized clinical tests, which are used in epidemiological studies and clinical testing. (1-3,23-28) Measurements of aspects of the STS movement have been obtained using techniques such as use of force plates? video analysis, (17,29-31) use of optoelectronic systems, (13-15,32-35) goniometry, (10,36) and accelerometry. (37)

Because the most recent review on the STS movement was published in 1991, (38) we believed an update was necessary to gain insight into studies on the effects of variables on the STS movement, especially in view of the new technology available to study the movement. The aims of our article are to review research on STS movement determinants and to describe the type and magnitude of their influence on the STS movement. In addition, we aimed to expose gaps in the literature and make recommendations for future research.

Methods

A search was made using MEDLINE (1980-2001) and the Science Citation Index Expanded of the Institute for Scientific Information (1988-2001) using the key words "chair," "mobility," "rising," "sit-to-stand," and "standing." References such as textbooks, presentations, and reports also were included. After reading the articles or abstracts, studies were included only when quantitative instrumental analyzing techniques were used to study STS movement performance in the subjects (patients and people without known impairments). The studies in this review were included on the basis of their design (ie, the design had to be experimental and aimed at elucidating the effect of determinants on the STS movement by manipulating the variables). Thus, descriptive and comparative studies were excluded, but because we included textbooks, presentations, and similar materials, there was not a requirement that articles be peer reviewed.

The STS movement determinants are factors that influence how the movement is performed. We categorized the studied determinants as chair related (eg, seat height), subject related (eg, age, muscle force), or strategy related (eg, speed or light conditions) (Tab. 1). Strategy-related determinants are those that are related to the execution of the STS movement. Although subject-related determinants can be investigated only by means of comparative studies, which was beyond the scope of our study, the types of patients investigated are indicated in Table 2. We judged studies according to the techniques used (eg, use of force plates, optoelectronic devices, or goniometers), number of movements analyzed, the determinants studied (ie, chair related, subject related, or strategy related), and the dependent variables (Tab. 2).

STS Movement Determinants in the Reviewed Studies

Of the 160 studies identified, we found 39 studies that addressed the effects of determinants on the STS movement using an experimental design (Tab. 2). We did not examine whether the results could be obtained consistently by multiple researchers (ie, we did not examine reliability of these judgments).

Chair-Related Determinants

The literature indicates that the chair has an influence on the performance of the STS movement (eg, the height of the seat can make an STS movement impossible). (39) Most research has been focused on the height of the seat, and few studies tried to clarify the influence of the armrest position, use of armrests, or the type of chair on the STS movement.

Seat height. Lowering the height of the seat makes the STS movement more demanding or even unsuccessful according to the literature we reviewed. (10,14,30,39-43) The minimum height for successful rising for elderly people (community-dwelling and nursing home residents 64-105 years of age) with chair rise difficulties appears to be 120% of lower leg length. (41) A lower seat apparently leads to increased angular velocity of the hip in order to stand (14,30,39,42) and to more repositioning of the feet (also called the "stabilization strategy"). (14,39) In young subjects (25-36 years of age) without impairments, lowering the seat of the chair from 115% to 65% of knee height results in an increase in trunk flexion angular velocity of almost 100% in order to stand. (14) A lower seat has been shown to increase trunk, knee, and ankle angular displacement. (30,42,43) Changing the seat height affects the maximum moment needed at the hip and knee. (15,42-44) Differences for hip and knee moments can be as large as 50% to 60%, with seat height having a greater influence on the moments needed at the knee than at the hip. (15,42-44) The changes in seat height can result in changing biomechanical demands (eg, the need to move the body's center of mass over a larger distance) or in an altered strategy (eg, "stabilization strategy," due to the imposed biomechanical demands by a different foot, trunk, or arm position).

Armrests. Issues related to the armrest use include positioning of the hands on the armrests, height of the armrests, and the moments exerted. There is no research on the relationship among the height of the armrests, seat height, hand positioning, and their cumulative effect on performance of the STS movement.

Using armrests, according to the articles we reviewed, results in lower moments at knee and hip; at the hip, a reduction of about 50% of the extension moment needed to perform the STS movement has been calculated. (40,44,45) Burdett et al (40) found no influence of the use of arms on joint angles in subjects without impairments (25-41 years of age). In a study by Alexander et al, (46) young and old subjects without impairments used a hand bar positioned in front of them to perform the STS movement. They found no differences in body segment rotations in the young subjects (19-31 years of age). A difference in trunk rotation was observed in the old subjects (63-86 years of age), although this movement was analyzed only at the moment of maximum anterior head displacement. (46)

Choir type. We found only 3 studies on the influence of specially designed chairs. (30,40,47) Different types of chairs designed to "ease" the STS movement were studied. (30,40,47) Wheeler et al (47) suggested a negative influence of seat posterior slant because of tilting the body's center of mass farther backward. Use of an ejector mechanism lowered vertical impulses applied to the armrests by 47% in patients with arthritis, but no differences were found for knee and ankle moments. (30)

Backrests. We found no experimental studies concerning the influence of backrests on STS movement. In only 8 studies (30,39,41,42,45-48) was a chair with a backrest used. When a backrest was used, it was to standardize the STS movement starting position. The influence of trunk position has been studied; however, this influence cannot necessarily be related to backrest use or backrest position, because the trunk position studied was not comparable to the trunk position using a backrest. (31)

Strategy-Related Determinants

Speed. Increasing speed of the STS movement increases the hip flexion, knee extension, and ankle dorsiflexion joint moments. (13) To increase reproducibility and comparability of the results of their studies, some authors (14,18,49) did not allow subjects to rise at their self-selected speeds. Subjects had to rise at a preset speed indicated by, for example, a metronome. (18) Other researchers studied the influence of speed on strategy, peak joint moment, phase changes, and lateral displacement. Pai and colleagues (33,34) reported that a faster STS movement influences the peak vertical momentum of the center of mass while the peak horizontal momentum remains relatively unchanged (data were given in graphs). A faster STS movement gave a shorter flexion and momentum-transfer phase. (19,29) Vander Linden and colleagues (19) reported no influence of speed on joint excursions. Gross et al (50) and Papa and Cappozzo, (51,52) however, described less hip flexion at the moment of seat-off in elderly subjects who stood rapidly. In several studies, (48,50,53,54) elderly subjects (64-84 years of age) were less able to increase the speed of their STS movement.

Foot positioning. Shepherd and colleagues (17) studied the effect of foot position (posterior, preferred, and anterior positions) prior to the start of the STS movement, and they showed a shorter movement time with feet placed posterior. With the posterior placement of the feet, hip flexion and hip flexion speed were lowered, whereas anterior placement of the feet increased the pre-extension phase. (17) Kawagoe et al (55) also showed an influence of posterior foot placement. Positioning the feet more posteriorly enabled lower maximum mean extension moments at the hip (148.8 N*m versus 32.7 N*m) to be used for the STS movement. (55) Hughes et al (39) described repositioning of the feet as a movement strategy to lower moments used for the STS movement, which they called "stabilization strategy." Munton et al (10) found no difference in electromyographic (EMG) activity of 6 large lower-extremity muscle groups with feet placed normal or posterior. Stevens et al (56) studied the effect of the initial lower-extremity posture, including foot posture, on the STS movement and reported that the preferred lower-extremity position gives less head movement and lower ground reaction forces.

Trunk positioning/movement. According to Shepherd and Gentile, (31) changing the initial trunk position to have more flexion did not change the peak support moment, but the duration of maximum support moment did increase. The duration of the extension phase also became longer when the trunk initially was more flexed. (31) Starting from a trunk position different from erect alters the kinematics and kinetics of the STS movement. For the condition "flexion of the trunk" (first flex the trunk toward the knees, before rising from the chair), Goulart and Valls-Sole (37) described a longer movement time than for normal STS movement condition and delayed seat-off, without joint angular changes. This observation was supported by Schenkman et al, (21) who described a momentum transfer strategy in which the momentum generated by the upper body is used during the extension phase.

Doorenbosch et al (49) studied the effect of an STS strategy aimed at maximum flexion of the trunk during the STS movement. This strategy resulted in kinematic changes around the hip, but the range of motion of the knee and ankle did not change. Using the maximum flexion strategy, 27% lower (net) knee joint moments than in natural rising were found. (49)

Arm movement. Study of the STS movement is often done with constraints on the use of the arms. (57) In most studies, use of the arms during the STS movement was not allowed. Subjects were often instructed to stand up with their hands in their lap, folded, sideways, placed on the knees, or fixating an object. Some authors (16,47) have reported that use of the arms during the STS movement is very common among elderly people and even among young people. Only Carr (57) studied the effect of arm movement strategy on the body's center of mass. Arm position during the STS movement appears, based on the literature, to influence the position of the body's center of mass. (57) The body's center of mass moves forward at the end of the STS movement when subjects point with their arms. (57) Restricting the arms leads to a different pattern of ankle angular displacement, with a much higher mean standard deviation than occurs with the arms free. This finding suggests that more adjustment of the strategy of rising is needed, using ongoing adjustment at the ankle joint during restricted arm movement. (57)

Terminal constraint. The terminal constraint is the required body position or activity at the end of the STS movement. The STS movement has been studied while the motion was aimed at standing quietly at the end of the movement. Pal and Lee (35) conducted a study with a constraint to fall after the movement instead of standing quietly at the end. No study has quantitatively explored the sit-to-walk movement.

Dark versus light. Visual control was manipulated while subjects performed the STS movement in light and darkness at 2 speeds. (48,53) No effect on movement time was found in young (20-25 years of age) and elderly (71-82 years of age) people when visual control was varied. (48,53) The speed of the center of mass, however, was lower in the blindfolded condition for the elderly subjects. (53)

Fixed joints. Only one study (58) concerned the influence of joint fixation on the level of control of STS movement performance using the so-called "uncontrolled manifold concept" (a cybernetic concept to describe results). This analysis showed that the position of the center of mass in the sagittal plane is controlled. No data on joint angle or angular velocity were given. Another study (36) analyzed the relationship between the active limitation in range of motion of the knee following total knee arthroplasty and the height of the seat when rising from a seated position. The subjects with larger limitations in active knee flexion (<100[degrees] of knee flexion) required a higher angular velocity of the hip to lift the trunk forward than did those with less limitation of knee flexion (>100[degrees] of knee flexion). (36)

Knee position. Positioning the knee in more extension than preferred prior to the STS movement appeared to lead to an increase of the hip joint angular displacement, with an increase of hip extension moments of 77%. (59) This experimental setup is to some extent comparable to the foot-forward setup as used by Shepherd and Koh (17) because foot forward will result in more knee extension.

Attention. No experimental study addressing the influence of attention on the performance of the STS movement in subjects without impairments could be found.

Training. Training can be a determinant in an experimental study. Hesse et al (60) studied the influence of 4 weeks training (4-week inpatient rehabilitation program; the physical therapists trained the patients to distribute equal weight on both legs and to avoid lateral compensatory tilt of the trunk) on the temporal and spatial variables of the STS movement. Only in a subgroup of people with left hemiparetic strokes was a difference noted.

Discussion and Conclusions

Method

General. In our review, we included only experimental studies. In an experimental study of the STS movement, the determinants are manipulated in order to explore their influence on performance. Not all of the studies reviewed, however, were completely experimental. Some articles included comparative or descriptive data. We believe that experimental studies are important because they provide the strongest evidence concerning the influence of the determinants. In these studies, only one determinant is usually manipulated while others are kept constant. In comparative studies, we believe conclusions are difficult to make because of the nonexperimental design. The relationship between subject-related determinants (eg, age, muscle force) and STS movement performance, in our view, is seldom unambiguous because subject-related determinants are generally examined in nonexperimental studies. For example, the influence of age on the ability to do an STS movement is often studied, (46,48,51,53,61-63) with age accounting for small differences in STS movement performance and a decreased ability to decrease movement time. Whether these differences in the STS movement are the result of increased age or of covariates such as muscle force, balance disturbances, neuromusculoskeletal changes, or changed motor control is not clear. Another example concerns muscular force as a determinant of STS movement performance. Less quadriceps femoris muscle force will affect the performance of the STS movement, and the time to do the STS movement will increase. (32,50,61,64) Related neuromusculoskeletal changes (eg, loss of trunk muscle force, loss of balance) may influence the performance of the STS movement to the same degree. When these related changes cannot be controlled for in a study, they can become confounding factors influencing the conclusions to be drawn from these studies.

Validity. Our review of studies on the determinants of what makes the STS movement possible led us to believe that many studies have good internal validity, but we did not use evaluative criteria or examination by multiple authors. There is, in our view, also evidence for construct validity for the measures used, because clinical tests for STS movement performance appear to us to be highly correlated with physical functioning in elderly people. (2,3) We question, however, whether the reviewed studies are externally valid for predicting changes in standing up. Standing up from a chair is almost never aimed at standing alone but is part of a goal-oriented behavior, such as going for a walk or picking up an object. Nevertheless, there are examples in which standing up is aimed at simple standing (eg, in church, watching sports).

Variability. There is intrasubject and intersubject variability in the performance of the STS movement. Variability can be the result of problems in defining the STS movement events, technical problems, or analysis of a low number of STS movements, or it can be considered as a sign of flexibility of performance during the STS movement. To lower variability and to ease analysis of the determinants, many constraints were used in the STS movement studies that we reviewed (Tab. 2). We contend that only in clinical physical performance is testing of the natural STS movement imitated (with self-selected speed and strategy). (9,23,24) Other explanations for variability may include a learning effect during performance of the STS movement, fatigue in repeating fast and frequent STS movements, and erroneous instructions leading to misinterpretation.

General Conclusions

In our review, we found that in most studies (27 of the 39 studies), a combination of force plate(s) and a motion analysis system (varying from video to a type of optoelectronic system) was used. Surface EMG analysis was used in 10 of the 39 studies. The number of analyzed STS movements per subject ranged from 1 to 15. In 7 of the 39 studies, only one trial was used for statistical analysis. The number of subjects studied ranged from 2 to 51. We believe, however, that general conclusions can be drawn. The height of the chair seat, the use of armrests, and foot positioning have a major influence on STS movement performance. A higher chair seat results in lower moments at hip and knee level (up to 60% and 50%, respectively). (10,14,30,39,40,42-44) Lowering the chair seat will increase the need for generation of momentum or repositioning of the feet to lower the moments needed. (14) Comparison of the results of the studies is difficult because of differences in study design and the fact that chair seat height is not always based on lower-extremity length. Using armrests will lower the moments needed at the knee by 50%, probably without influencing the range of motion of the joints. (40,44,46) There were no reports on the interaction between the height of the armrests, chair seat height, or hand positioning and their cumulative effect on STS movement performance. Repositioning of feet appears to influence the STS movement strategy, enabling lower peak moments at the hip and knee. (17,19,39,55,65) No experimental study was found that addressed the influence of the use of a backrest. The influence of trunk position has been studied; however, trunk position cannot be related to backrest position, because the studied trunk position is not comparable to the trunk position using a backrest. (31)

Clinical Significance

The ability to perform an STS movement is an important skill. In elderly people, the inability to perform this basic skill can lead to institutionalization, impaired ADL functioning, and impaired mobility. (2,3) Consequently, this movement is frequently assessed in clinical practice. Knowledge of determinants of the STS movement, therefore, is important for clinicians interested in evaluating the ability to do an STS movement. For a proper evaluation of the STS movement in a clinical setting, we contend that standardization of the evaluation should be done in regard to type of chair, chair seat height, positioning of feet, and the use of armrests. Results of experimental studies show that these variables influence the performance of the STS movement. Neglecting these variables may result in an inability to measure actual changes in STS movement performance of a patient. Furthermore, problems in STS movement performance may be obscured without standardization. Another consequence may be that apparent changes or discrepancies may not actually be present. All of these factors can lead to suboptimal choices and decisions with respect to prognosis, planning, and therapy.

Recommendations

We believe that in both experimental and comparative STS movement studies, there needs to be control of variables that can influence STS movement performance. Some determinants (eg, chair seat height, speed, position of feet) have been studied extensively. Others (eg, the effects of footwear on STS movement performance) have not been well studied (although the footwear type does influence the performance of the Timed Up & Go Test (66)). The interaction among determinants has been studied to some extent. (19,30,48,53,55) More research is needed, however, on the interaction of variables such as use of armrests, chair seat height, and foot positioning.

All of the studies we examined were directed at the level of impairment. Studying functional performance, in our opinion, should also include testing at the level of skills. (67,68) To analyze the skill of a subject to perform the STS movement, it may be necessary to evaluate the abilities of that subject to cope with changing constraints (eg, STS movement at different speeds, at different chair seat heights, STS movement versus sit-to-walk movement, light versus darkness). To gain insight into the influence of the determinants on the STS movement may entail using other biomechanical models or paradigms. (68,69) New techniques (eg, ambulatory techniques that register body posture and movements in the real-life environment of the subject) raise new research questions. To enhance the validity of data obtained in future studies and the generalizability of the results, new methods of research (which can be used outside the gait laboratory (70)), we believe, should be evaluated.

Table 1.
Number of Experiments Performed in the 39 Reviewed Studies
Investigating Determinants of the Sit-to-Stand Movement (a)

Chair-Related
Determinants                                         n

1. Height of chair seat                             12
2. With armrests                                     5
3. Chair special type                                3
4. With backrest                                     0

Subject-Related
Determinants

1. Age                                               0
2. Disease (eg, stroke, arthritis, low back pain)    0
3. Muscle force                                      0
4. No footwear                                       0

Strategy-Related
Determinants

 1. Speed                                           11
 2. Foot position                                    5
 3. Trunk position/movement                          3
 4. Arm use with armrest                             5
 5. Terminal constraint                              1
 6. Arm movement                                     1
 7. Dark versus light                                2
 8. "Fixed" joints                                   1
 9. Knee position                                    1
10. Attention                                        0
11. Training                                         1

(a) In some studies, more than one determinant was investigated. The
constrained determinants are indicated in Table 2 (numbers in columns
under "Determinant Constrained" heading in Tab. 2 refer to the details
of detexqninants listed in Tab. 1).
Table 2.
Details of the Experimental Studies That Addressed Determinants of the
Sit-to-Stand (STS) Movement (a)

                        Year        Study
Authors                 Published   Technique             Rep

Alexander et al (46)    1991        Video (3 samples      3 (1)
                                      in total)
                                    Handle
                                      dynamometry
                                    Chair instrumented

Arborelius et al (44)   1992        Force plate (feet)    2
                                    Video (digitized)
                                    sEMG
                                    Borg Scale

Burdett et al (40)      1985        Force plate           1
                                    Cinecamera
                                      (digitized)

Carr (57)               1992        Force plate (feet)    6
                                    Video (digitized)

Doorenbosch             1994        Force plate (feet)    5 (2)
  et al (49)                        Cinefilm, motion
                                      analyzer
                                    sEMG

Fleckenstein            1988        Cinecamera            1
  et al (59)                          (digitized)

Goulart and Valls-      1999        Accelerometry         5
  Sole (37)                         sEMG
                                    Chair switch

Gross et al (50)        1998        Force plates (2,      3 (1)
                                      feet/chair)
                                    Motion analysis
                                      system
                                    sEMG
                                    Dynamometry 1
                                      repetition
                                      maximum

Hanke et al (29)        1995        Force plates (2,      5
                                      feet/chair)
                                    2 video

Hesse et al (54)        1996        Force plates (2,      5
                                      feet/chair)

Hesse et al (60)        1998        Force plates (2,      15
                                      feet/chair)

Hughes and              1996        Force plate (feet)    1
  Schenkman (15)                    Motion analysis
                                      system

Hughes et al (39)       1994        1 video (digitized)   1

Hughes et al (32)       1996        Force plate (feet)    1
                                    Motion analysis
                                      system
                                    Dynamometer

Itokazu et al (36)      1998        Force plate           3
                                    Chair switch
                                    Goniometers (3)

Kawagoe et al (55)      2000        Force plates (2,      5
                                      feet)
                                    Motion analysis
                                      system
                                    sEMG

Khemlani et al (65)     1999        Force plate (foot     6
                                      right)
                                    sEMG
                                    Video
                                    Pressure-sensitive
                                      chair switch

Kotake et al (22)       1993        Motion analysis       2
                                      system
                                    Isometric
                                      dynamometer

Mourey et al (48)       1998        Force plate (feet)    3
                                    Motion analysis
                                      system, 3
                                      cameras

Mourey et al (53)       2000        Force plate (feet)    3
                                    Motion analysis
                                      system, 2
                                      cameras

Munro et al (30)        1998        Force plate (feet)    3 (1)
                                    Video
                                    Armrest load cell

Munton et al (10)       1984        Cinecamera            1
                                    Goniometer
                                    sEMG

Pai and Lee (35)        1994        Force plate (stool)   5
                                    Motion analysis
                                      system

Pai and Rogers (13)     1991        Force plates (2,      5
                                      feet/chair)
                                    Motion analysis
                                      system

Pai and Rogers (34)     1990        Force plates (2,      5
                                      feet/chair)
                                    Motion analysis
                                      system

Pai et al (33)          1994        Force plates (2,      5 (3)
                                      feet/chair)
                                    WATSMART LED
                                      motion analysis
                                      system

Papa and                1999        Force plate (feet/    5
  Cappozzo (52)                       chair)
                                    Load cell

Papa and                2000        Force plate (feet/    5
  Cappozzo (51)                       chair)
                                    Load cell

Rodosky et al (42)      1989        Force plate           2 left
                                    Motion analysis       2 right
                                      system

Schenkman               1996        Force plates (2,      2
  et al (14)                          feet)
                                    Motion analysis
                                      system

Scholz and              1999        Motion analysis       10
  Schoner (58)                        system 2
                                      cameras

Seedhom and             1976        Force plate (feet)    2
  Terayamo (45)                     Cinecamera
                                    UV oscillograph

Shepherd and            1996        Force plate (feet)    ncs
  Koh (17)                          Pressure switch
                                    Video

Shepherd and            1994        Force plate (stool)   6
  Gentile (31)                      Video
                                    Chair switch

Stevens et al (56)      1989        Force plate           8
                                    Photographic 1
                                    sEMG

Su et al (43)           1998        Force plates (2,      ncs
                                      feet)
                                    Motion analysis
                                      system

Vander Linden           1994        Force plate           5 (4)
  et al (19)                        Motion analysis
                                      system
                                    sEMG

Weiner et al (41)       1993        Motion analysis       1
                                      system
                                    VAS

Wheeler et al (47)      1985        Video 1 manual (1     3
                                      sample)
                                    Electrogoniometer
                                    EMG

                        Subjects
                                         Age (y)
Authors                 N    Type        [bar]X    Range

Alexander et al (46)    51   17 y        23.2      19-31
                             23 o        72.4      63-86
                             11 o/d      84.4      75-92

Arborelius et al (44)   9    9 m         26        23-34

Burdett et al (40)      14   10 m        33.3      25-41
                             4 m/d       52        19-67

Carr (57)               6    6 m                   20-30

Doorenbosch             9    3 m, 6 f    27
  et al (49)

Fleckenstein            10   5 m, 5 f    25.4
  et al (59)

Goulart and Valls-      20   12 m, 8 f   34.7      25-45
  Sole (37)

Gross et al (50)        38   12 f/y      24.2
                             26 f/o      70.1      64-84

Hanke et al (29)        19   9 m         32.4      25-38
                             10 f        31.1      27-36

Hesse et al (54)        20   9m, 11 f    27.8      19-40

Hesse et al (60)        35   17 m/h      64.8      59-79
                             18 f/h

Hughes and              18   18 o/d      74.8
  Schenkman (15)

Hughes et al (39)       22   22 o/a/d    72.0      64-105

Hughes et al (32)       21   5m, 5       25
                               f/y       78
                             5 m, 6
                               f/o/d

Itokazu et al (36)      46   tka         ncs
                             16 oa
                             30 art

Kawagoe et al (55)      10   10 m        30.2

Khemlani et al (65)     9    9 m         29        20-35

Kotake et al (22)       12   12 m        30.7      22-40

Mourey et al (48)       13   7 y         22.8      20-25
                             5 o         73.2      71-82

Mourey et al (53)       7    4 m/y,      22.8      20-25
                             3 f/y
                             7 o         75.1      71-82

Munro et al (30)        12   12 o/f/ra   65.5

Munton et al (10)       9    5           ncs
                             4 art

Pai and Lee (35)        9    4 m, 5 f              27-39

Pai and Rogers (13)     8    4 m, 4 f              26-38

Pai and Rogers (34)     10   5 m, 5 f              26-38

Pai et al (33)          32   8 m/y, 8    31.9      25-38
                               f/Y
                             8 m/o, 8    72.1      63-84
                               f/o

Papa and                12   6 m, 6 f              22-34
  Cappozzo (52)

Papa and                51   7 m/y, 9              22-34
  Cappozzo (51)                f/Y
                             12 m/o,               65-81
                             23 f/o

Rodosky et al (42)      10   5 m, 5 f    25.5      20-35

Schenkman               21   11 y        28.9      25-36
  et al (14)                 10 o        67.3      61-79

Scholz and              9    5 m, 4 f              22-28
  Schoner (58)

Seedhom and             2    ncs         ncs
  Terayamo (45)

Shepherd and            6    6 f         21.3      18-25
  Koh (17)

Shepherd and            6    6 m                   20-30
  Gentile (31)

Stevens et al (56)      2    ncs         ncs

Su et al (43)           38   12 tka, 4   64.8      57-75
                               m, 8 f
                             12 o, 5     61.7      54-75
                               m, 6 f
                             14 oa, 2    ncs
                               m, 12f

Vander Linden           8    1 m, 7 f    68.8      61-77
  et al (19)

Weiner et al (41)       22   o/a/d       ncs

Wheeler et al (47)      20   10 f/y      24        22-28
                               10 f/o    75        67-81

                        Determinant Constrained (b)
                        Chair     Subject   Strategy
Authors                 Related   Related   Related

Alexander et al (46)    1, 2, 4   4         2, 4

Arborelius et al (44)   2                   4

Burdett et al (40)      2, 3      4         2, 4

Carr (57)               1                   2, 4, 6

Doorenbosch             1                   1, 2, 4
  et al (49)

Fleckenstein            1         4         4, 9
  et al (59)

Goulart and Valls-      1                   2, 3, 4
  Sole (37)

Gross et al (50)        1                   1, 4

Hanke et al (29)        1         1, 2, 4

Hesse et al (54)        1         2, 4

Hesse et al (60)        1                   2

Hughes and              1         4         4
  Schenkman (15)

Hughes et al (39)       4         4         2, 4

Hughes et al (32)                           2, 4

Itokazu et al (36)      1

Kawagoe et al (55)      1                   2

Khemlani et al (65)     1                   2, 3, 4

Kotake et al (22)       1         4         1, 2, 4

Mourey et al (48)       1, 4                4, 7

Mourey et al (53)       1,4                 3, 4, 7

Munro et al (30)        2, 3, 4             3, 4

Munton et al (10)                           2, 4

Pai and Lee (35)        1         4         5

Pai and Rogers (13)     1                   1, 4

Pai and Rogers (34)     1                   1, 4

Pai et al (33)          1                   1, 4

Papa and                1                   1, 2, 3, 4
  Cappozzo (52)

Papa and                1                   1, 2, 3, 4
  Cappozzo (51)

Rodosky et al (42)      4                   2, 4

Schenkman                         4         1, 2, 4
  et al (14)

Scholz and              1                   2, 3, 4, 8
  Schoner (58)

Seedhom and             1, 2, 4
  Terayamo (45)

Shepherd and            1                   2, 4
  Koh (17)

Shepherd and            1         4         2, 4
  Gentile (31)

Stevens et al (56)      1                   2, 4

Su et al (43)                               4

Vander Linden           1                   1, 2, 4
  et al (19)

Weiner et al (41)       4         4         2, 4

Wheeler et al (47)      1,4       4

                                              "Dependent"
Authors                 Determinant           Variables

Alexander et al (46)    With/without arm      Movement time,
                          use                   kinematic data,
                                                phase duration,
                                                hand forces

Arborelius et al (44)   3 chair heights       Difficulty Borg Scale
                          (kh, kh+1/3           estimation of effort,
                          upper leg,            load-bearing seat,
                          kh+2/3 upper          joint moments, sEMG
                          leg)
                        Armrest

Burdett et al (40)      2 types of chair      Kinematic data, joint
                          (with/without         moments
                          arm use)

Carr (57)               3 arm movement        Movement time, COM
                          conditions            position and
                                                horizontal and vertical
                                                linear momentum,
                                                support moment,
                                                angular displacement
                                                ankle joint

Doorenbosch             Trunk movement        Movement time,
  et al (49)              (natural vs           kinematic data, joint
                          full flexion)         moments, sEMG

Fleckenstein            2 knee angles         Movement time kinematic
  et al (59)              (75[degrees],         data, joint moments,
                          105[degrees])

Goulart and Valls-      6 types STS (trunk    EMG phases
  Sole (37)               straight, flexion
                          of trunk, feet
                          anterior, knees
                          first, head
                          supported,
                          reference)

Gross et al (50)        2 speeds (normal,     Movement time,
                          as fast as            moments, torque hip/
                          possible)             knee, ground reaction
                                                forces, kinematics

Hanke et al (29)        3 speeds (normal,     Movement time, COM
                          as slow and as        momentum, phase
                          fast as possible)     duration

Hesse et al (54)        3 speeds (natural,    Movement time, COM
                          as slow and as        displacement
                          fast as possible)

Hesse et al (60)        Pretraining/          Movement time, time
                          posttraining          seat-off, body weight
                                                distribution, COM
                                                velocity/displacement

Hughes and              2 chair heights       Movement time, hip
  Schenkman (15)          (kh and lowest        flexion velocity,
                          possible)             COM/base of support
                                                separation at
                                                lift-off

Hughes et al (39)       6 chair heights       Movement time, COM
                          (43.2-55.9 cm         movement/velocity
                          with an interval
                          of 2.5 cm)

Hughes et al (32)       3 chair heights       Joint moments, isometric
                          (58 cm, kh and        quadriceps femoris
                          lowest possible)      muscle force

Itokazu et al (36)      Knee flexion          Movement time, hip/
                          <100[degrees] and     knee flexion angle and
                          >100[degrees]         angular velocity
                        2 chair heights
                          (100%, 120%
                          of kh)

Kawagoe et al (55)      3 chair heights       Movement time, temporal
                          (30, 40, 50           data, kinematics,
                          cm)                   center-of-gravity
                        3 foot positions        position, ground
                                                reaction force

Khemlani et al (65)     2 foot positions      Movement time, EMG
                          (anterior/            phasing, extension
                          posterior)            moments, temporal
                                                data

Kotake et al (22)       3 speeds (natural,    Movement time,
                          fast, stow)           kinematic data, phase
                                                duration, joint
                                                moments

Mourey et al (48)       Young vs elderly,     Movement time,
                          dark and light,       kinematic data, head
                        2 speeds (normal,       stability
                          fast)

Mourey et al (53)       Young vs elderly,     Movement time,
                          dark and light        kinematic data
                        2 speeds (normal,
                          fast)

Munro et al (30)        High (54 cm) vs       Movement time,
                          low (45 cm)           kinematics, armrest
                          chair seat            force, exertion (Borg
                        Eject vs noneject       Scale), pain (VAS)
                          use

Munton et al (10)       2 chair seat          sEMG pattem
                          heights (42 and
                          59.5 cm)
                        With/without arm
                          use
                        2 foot positions
                          (normal,
                          posterior)

Pai and Lee (35)        3 speeds (natural,    Movement time, temporal
                          as fast as            parameters, COM
                          possible,             displacement,
                          fast+"fall")          moments

Pai and Rogers (13)     3 speeds (natural,    Movement time,
                          slow, fast)           kinematic data, joint
                                                moments

Pai and Rogers (34)     3 speeds (natural,    Movement time, COM
                          slow, fast)           movement, impulse
                                                momentum

Pai et al (33)          3 speeds (natural,    Movement time, COM
                          slow, fast)           momentum, COM
                                                movement, phase
                                                duration

Papa and                2 speeds (self-       Movement time,
  Cappozzo (52)           selected/             kinematic data,
                          maximal)              rotational/linear
                                                actuator

Papa and                2 speeds (self-       Movement time,
  Cappozzo (51)           selected/             kinematic data,
                          maximal)              rotational/linear
                                                actuator

Rodosky et al (42)      4 chair heights       Kinematic data, joint
                          (65%, 80%,            moments
                          100%, 115%
                          of kh)

Schenkman               4 chair heights       Kinematic data, phase
  et al (14)              (65%, 80%,            duration
                          100%, and
                          115% of kh)

Scholz and              3 conditions          COM, head, hand
  Schoner (58)            (normal/rigid         trajectory
                          boots/narrow
                          base)

Seedhom and             With/without arm      Moments, force
  Terayamo (45)           use                   (quadriceps femoris,
                                                hamstring, calf
                                                muscles)

Shepherd and            3 foot positions      Movement time,
  Koh (17)                                      kinematic data, joint
                                                moments, moment of
                                                support

Shepherd and            3 trunk positions     Kinematic data, phase
  Gentile (31)                                  duration, joint
                                                moments, moment of
                                                support

Stevens et al (56)      Leg position          Ground reaction forces,
                          guided/unguided       head movement,
                                                sEMG pattern

Su et al (43)           4 chair heights       Movement time,
                          (65%, 80%,            kinematic data, COM
                          100%, 115%            displacement, joint
                          kh)                   flexion moments

Vander Linden           2 speeds (self-       Movement time,
  et al (19)              selected, fast)       kinematic data, phase
                        2 foot positions        duration, ground
                          (18[degrees] or       reaction farces, sEMG
                          5[degrees]            pattern
                          dorsiflexion)

Weiner et al (41)       6 chair heights       Kinematic data,
                          (17-22 in,            difficulty (VAS), STS
                          interval 1 in)        success ratio

Wheeler et al (47)      2 types of chair      Movement time,
                                                kinematic data, sEMG
                                                pattern, hand/foot
                                                placement

(a) Rep=repetitions (number analyzed in parentheses), m=male, f=female,
y=young, o=old, a=able, d=disabled, h=hemiplegia, art=arthritis,
fa=rheumatoid arthritis, oa=osteoarthritis, tka=total-knee
arthroplasty, ncs=not clearly stated, sEMG=surface electromyography,
kh=knee height, COM=center of mass, VAS=visual analog scale,
WATSMART=Waterloo Spatial Motion Analysis Recording Technique,
LED=light-emitting diode; UV=ultraviolet.

(b) Numbers refer to determinants listed in Table 1.

All authors provided concept/idea/research design and writing. Dr Janssen provided data collection and analysis. Dr Stam provided project management, fund procurement, and facilities/equipment. Dr Bussmann and Dr Stam provided consultation (including review of manuscript before submission).

No grants were received for this study.

This article was submitted July 19, 2001, and was accepted March 19, 2002.

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WGM Janssen, MD, is Rehabilitation Specialist, Department of Rehabilitation, University Hospital Rotterdam, Dr Molewaterplein 40, 3015 GD Rotterdam, the Netherlands ([e-mail]). Address all correspondence to Dr Janssen.

HBJ Bussmann, PT, PhD, is Assistant Professor, Department of Rehabilitation, Erasmus University Rotterdam, Rotterdam, the Netherlands.

HJ Stam, MD, PhD, is Rehabilitation Specialist, Professor and Head of the Department of Rehabilitation Medicine, University Hospital Rotterdam and Erasmus University Rotterdam.