Treadmill training for an infant born preterm with a grade III intraventricular hemorrhage.

Treadmill stepping has been used to study dynamic systems theory, a conceptual framework for both motor development and physical therapy intervention. (1,2) According to dynamic systems theory, motor behavior is a complex, self-organizing interaction of multiple subsystems of the individual, the demands of the task, and the conditions of the environment. (1,2) No single subsystem is more important than any other, and each subsystem develop at its own rate. Changes in motor behavior occur as a series of phase shifts resulting from changes in critical values of one or more of the subsystems of the individual, task, or environment. (1,2) For example, postural control, extensor muscle strength (the amount of force a muscle produces), balance, and other necessary components increase gradually in infants until they reach a critical level and the infants are able to walk. Although the onset of walking appears to develop suddenly, it is due to continuous development of one or more critical subsystems.

Using a small motorized treadmill to alter the demands of the task and environment can alter early stepping behavior. Thelen and Ulrich (2) demonstrated that infants born at full term took steps when they were held in standing position with their feet placed on a moving treadmill many months before they produced independent steps. They found that infants took alternating steps on the treadmill from the first month after birth and produced coordinated, alternating, adult-like steps on the treadmill by 7 months of age. Davis et al (3) showed that infants born preterm at low risk for neuromotor complications produced alternating steps on a treadmill and were responsive to changes in treadmill speeds, similar to full-term infants. Vereijken and Thelen (4) demonstrated that the number of steps can be increased with training on a treadmill. These researchers also found that treadmill training was associated with a larger increase in number of steps in infants at 3 months of age with unstable treadmill stepping patterns than in 7-month-old infants with stable treadmill stepping patterns. (4) These results lend support to one of the theoretical constructs of the dynamic systems theory, which suggests that intervention is most beneficial if an individual's motor behavior is unstable. (3,4)

In addition to being used to investigate dynamic systems theory and motor development, treadmill training has been incorporated into physical therapy intervention for children with cerebral palsy and Down syndrome. Richards and colleagues (5) showed that it was feasible to add treadmill training to a traditional physical therapy program for 4 children from 1.7 for 2.3 years of age with cerebral palsy who were not yet ambulatory. Two of the children showed improvement in supported gait, and 2 children achieved independent ambulation during the study. Schindl and colleagues (6) demonstrated improved walking and other motor skills, such as transferring, independent standing, and stair climbing, in 8 of 10 children between 6 and 12 years of age with cerebral palsy who received treadmill training. These studies demonstrated the benefit of treadmill training in nonambulatory children diagnosed with cerebral palsy.

The best evidence for treadmill training in preambulatory infants, however, was a randomized study by Ulrich and colleagues. (7) Fifteen infants with Down syndrome who received treadmill training 5 times a week attained 2 developmental milestones related to walking at a faster rate than a control group of 15 infants with Down syndrome who did not receive treadmill training: they walked with support 73.8 days earlier and walked independently 101 days earlier. (7) Families in this study provided treadmill training in the home from the time the children could sit independently until the children walked, showing that treadmill training is a feasible home program for young infants with delayed motor development. Earlier walking often is believed to be desirable because children who walk may interact more efficiently with their environment, with adults, and with other children, thus potentially contributing to cognitive and social development. (7)

Studies (1-7) have shown that typically developing infants, infants born preterm at low risk for neuromotor delays, infants with Down syndrome, and nonambulatory children with cerebral palsy all produce steps on a motorized treadmill and may benefit from treadmill training as part of physical therapy intervention. These studies also suggest that treadmill training may be beneficial for infants who are not yet ambulatory and who are at high risk for neuromotor delays, such as infants born preterm (<37 weeks of gestation) who have experienced medical of neurological complications during the neonatal period. Medical complications of infants born preterm that are associated with poor neuromotor outcome, cerebral palsy, delayed walking, and poor quality of walking include gestational age of <30 weeks, low birth weight (< 1,001 g), bronchopulmonary dysplasia, greater than 7 days of mechanical ventilation, greater than 28 days of oxygen use, and stage III/IV retinopathy of prematurity. Neurological complications associated with poor neuromotor outcome are grade III/IV intraventricular hemorrhage, cystic periventricular leukomalacia, and moderate to severe ventriculomegaly. (8,9) Delayed walking, defined as attaining independent walking at or after 18 months corrected age (CA), occurred in 11% to 13.5% of infants who had medical and neurological complications following preterm birth. (8,10) Poor quality of walking, such as walking with atypical arm posture or foot position, also has been documented in infants born preterm and having complications. (11,12) Because infants born preterm are at risk for cerebral palsy, for delays in motor development (including walking), and for compromised movement quality, early intervention for these children usually includes physical therapy. No studies reporting the use of treadmill training with children born preterm and at risk for motor impairments have been published.

One purpose of this case report is to describe the feasibility of treadmill training as part of a physical therapy program for an infant born preterm at high risk for neuromotor delays. Another purpose is to describe the infant's treadmill stepping during training and post-training periods.

Case Description

Description of Infant

The infant, a boy of Hispanic background, was born at 29 weeks of gestation weighing 1,161 g. He was hospitalized in the neonatal intensive care unit for 91/2 weeks after birth. He had no congenital anomalies or surgeries; however, he had multiple risk factors associated with poor developmental outcome. (8-10) These risk factors included a documented grade III/IV intraventricular hemorrhage on the left side with mild bilateral hydrocephalus and ventriculomegaly greater on the left side than on the right side, bronchopulmonary dysplasia, and oxygen use during hospitalization and at home following hospital discharge. Following discharge from the hospital, the infant was seen in a nursery follow-up clinic. The clinic team, including the physical therapist, had concerns about his motor development, and he was referred to our clinic for physical therapy.

Initial Examination

The infant was initially seen at 8 months of age (51/4 months CA). We tested his motor development with the Alberta Infant Motor Scale (AIMS). (13) The AIMS is an observational test of motor development designed to: (1) discriminate between infants with immature, atypical development and those with typical development and (2) evaluate small changes in motor performance due to intervention of maturation. The test developers demonstrated concurrent validity of .84 to .99 and interrater reliability of .85 to .97. (13) We did not estimate the reliability of our measurements. Figure 1 shows that the infant's motor skills were below the fifth percentile for his age (corrected for prematurity). The motor skills we observed were: he was beginning to push himself up on his forearms and raise his head in a prone position, he could maintain a chin tuck and bring his hands to midline in a supine position, and he lifted his head briefly in a supported sitting position (Tab. 1). In a supported standing position, he did not bear weight on his legs. Furthermore, we observed that he used the right side of his body less than the left side, he thrusted backward into extension when placed in a supported sitting position, and overall he had decreased quantity of movement. Because of his delays in motor development, extensor thrusting, asymmetries, paucity of movement, and biological risk factors, we recommended that the infant receive physical therapy 1 to 2 times per week to attempt to improve his overall developmental level and that we work with the family on developmentally appropriate home program activities. This frequency was based on our clinical judgment that frequent intervention and updating of the infant's home program might help him to progress quickly, particularly because of his young age. The family expressed interest in having this level of intervention for their child.

Prior to initiating treadmill training, treadmill stepping was videotaped using Davis and colleagues' protocol for videotaping treadmill steps in infants born preterm at low risk for neuromotor delays. (3) This was done to obtain baseline information. The infant was undressed, and his diaper was removed. Five 1.9-cm (3/4-in) reflective markers were attached on his right side with dark-colored adhesive strips to provide maximal contrast. Markers were placed on the lateral midline of the trunk, lateral thigh crease, lateral femoral condyle, lateral malleolus, and lateral fifth metatarsal head. The infant was placed in a standing position on a small, motorized treadmill (similar to the treadmill described by Thelen and [Ulrich.sup.2]) and was allowed to bear as much weight through his lower extremities (LEs) as possible. The physical therapist held the infant facing away from herself and facing toward the mother, with the treadmill belt pulling his LEs backward. This position was chosen based on our pilot work with typically developing infants who preferred facing away from the physical therapist. Stepping was videotaped for 20 seconds at each of the following speed conditions: stationary, 10 cm/s, 15 cm/s, 20 cm/s, and stationary. The therapist did not facilitate stepping. She supported the infant so his feet were on the treadmill belt, and she repositioned him if the belt pulled his feet too far backward. Stepping patterns were recorded using 2 video cameras (Panasonic WV-CL350,* one with a Sanyo GVR S955 VCR* and one with a Panasonic AG-1970P VCR*) placed to the right of treadmill. The cameras were at 90 degrees to one another and 45 degrees to the treadmill, with one toward the front and the other toward the back (Fig. 2). During videotaping the infant's arousal level (l=asleep to 6=crying) (14) was recorded every 20 seconds when the treadmill belt speed was changed by the individual who changed the speed. The mean of all ratings for arousal level over the course of the study was 4.01 (SD=0.4, mode=4), an alert state. At the initial examination, the infant did not take steps at any of the speed conditions. He did not take weight through his LEs, and he allowed them to be pulled back by the treadmill belt.

[FIGURE 2 OMITTED]

Intervention

Physical therapy intervention was provided twice weekly, consisting of activities to encourage motor development, antigravity control, and symmetry in all positions. Initially, we focused on helping the infant assume and maintain a prone position on his elbows, reach for his feet and toys while in a supine position, decrease extensor thrusting in the sitting position, increase LE weight bearing in a standing position, and increase use of the right arm in all positions.

After approximately 3 weeks of physical therapy, when the infant was 6 months CA, physical therapy activities progressed to include lifting the pelvis off the surface in a supine position, assuming and maintaining a prone position with arms extended and with the pelvis on the surface, reaching for toys in a prone position, and sitting alone with UE support. Later activities included rolling in both directions, independent sitting without UE support and pivoting in a prone position (all initiated at 7 months CA), assuming an all-fours position (9 months CA), standing with UE support, walking with hands held, and moving between various positions (10 months CA). Quantity of movement was encouraged, as this infant seemed relatively inactive. Home program suggestions were given to the mother regarding appropriate positioning and play activities to facilitate development and encourage the child to move more by interacting with toys and family members. She was able to demonstrate the home program correctly and reportedly carried out the suggestions several times daily.

Treadmill training was carried out 3 times a week, early in the afternoon when the infant was awake and alert, using Veriejken and Thelen's training protocol. (4) We videotaped treadmill stepping on another day each week, early in the afternoon; therefore, the infant was on the treadmill 4 times a week, similar to training group infants in Veriejken and Thelen's study. (4) The infant was undressed, and his diaper was removed. He was held in the standing position on the treadmill and was allowed to bear as much weight on his feet as possible. The treadmill ran at a speed of 15 cm/s for 2 minutes 20 seconds. We chose 15 cm/s because it was the middle speed of the treadmill test speeds and we were interested to know if stepping behaviors would carry over to the faster and slower speeds. The infant was given a 2-minute rest period followed by another 2-minute 20-second training period. (4) Treadmill training was done prior to the physical therapy intervention so the infant would not be fatigued when on the treadmill.

For the first 12 weeks, the infant and his mother were brought to our clinic for training. During the first 6 weeks of treadmill training, the physical therapist held the infant from behind (facing away from the therapist) so that the mother, who was standing in front of the infant, could entertain him. Because the infant took no steps when held from behind, the physical therapist moved to the opposite end of the treadmill. In this position the infant faced the physical therapist. In both positions, the treadmill belt pulled the infant's LEs backward (Fig. 3). Because no published literature described treadmill training for infants at high risk for neuromotor problems, we decided a priori that we would not change any training conditions for the first 6 weeks. The infant received an additional 6 weeks of treadmill training at the clinic, for a total of 12 weeks.

[FIGURE 3 OMITTED]

For the next 11 weeks, the treadmill was taken to the infant's home and the mother did the training. This was done for the convenience of the infant, the family, and the physical therapist, and because the infant was doing well with treadmill training without adverse effects or apparent discomfort. For example, the infant did not fuss or cry with home treadmill training, and he continued to step when on the treadmill. The physical therapist taught treadmill training to the mother in the clinic, where she demonstrated it correctly. She continued the same protocol of 2 minutes 20 seconds on the treadmill at 15 cm/s, followed by 2 minutes of rest and then another 2 minutes 20 seconds on the treadmill. We asked each week when they came to the clinic for videotaping whether she had done the training and how the infant had responded. She was able to describe training sessions and the infant's response in detail. In addition, stepping frequency and step type progressed consistently during this period. We felt confident that training was carried out as prescribed.

Treadmill training was discontinued after 23 weeks of training when the infant consistently produced alternating steps on the treadmill 3 weeks in a row during the weekly videotape session, determined through observation of treadmill stepping patterns during videotaping. We stopped treadmill training at this point because we believed that the infant would continue stepping without ongoing training once he began to consistently take alternating steps. Furthermore, we monitored treadmill stepping by videotaping the infant on the treadmill every other week after training was discontinued, If the infant had stopped stepping, stopped taking alternating steps, or the variability of step type had increased, we would have resumed treadmill training. Treadmill stepping was videotaped once a week during the 23-week training period. Treadmill stepping was videotaped every other week for the 28-week posttraining phase, and the infant was only on the treadmill during videotaping. When the infant was able to take 3 independent steps on the ground, we stopped videotaping treadmill stepping because we believed his stepping patterns were stable and that we would not see additional changes. (4)

Videotape Analyses

We analyzed each videotape 2 times. First, we visually analyzed videotape segments to determine if the infant stepped. Because the infant did not produce any steps during the first 7 trials (initial trial and weeks 1-6), we did not analyze the videotapes in detail. Frame-by-frame videotape analysis was carried out beginning with trial 8 (6 1/2 months CA) when the infant began taking steps on the treadmill, using the method described in previous studies of infant treadmill stepping. (2-4) Frame numbers were superimposed onto the videotapes; the final 15 seconds of each speed was analyzed to allow several seconds for the infant to adjust to the change in belt speed. The frame numbers indicating the beginning of swing phase, foot initial contact, and end stance were recorded for each foot; swing, stance, and step cycle duration were calculated from the frame numbers. Foot position (heel, toe, medial, lateral, or foot flat) at initial contact and mid-stance were recorded. There were very few medial or lateral steps, so we further collapsed foot position to heel/foot flat or toe. The type of step was identified using the 4 stepping patterns described by Thelen and Ulrich (2): single step, alternating step, parallel step, and double step (Tab. 2). Total number of steps, proportion of step type, and number of alternating steps were calculated for each treadmill speed once the infant began stepping.

Outcomes

Weeks 1-6: Treadmill Training Holding Infant From Behind

The AIMS (13) was repeated at the end of the first 6 weeks of intervention. The infant's score continued to be below the fifth percentile for his CA. His motor development included holding his head at 90 degrees in a prone position, sitting alone momentarily without UE support, and actively bearing weight on his LEs in a supported standing position (Tab. 1). We continued to observe asymmetries and less use of his right side than his left side.

Weeks 6-23: Treadmill Training Holding Infant From Front

Testing with the AIMS, (13) administered at weeks 7, 14, and 19 of treadmill training, revealed that the infant's motor development progressed at a steady rate but continued to be well below the fifth percentile for his CA (Fig. 1). During this period, he began playing more in a prone position and rolled from a prone position to a supine position and back, primarily over the left side and without trunk rotation (Tab. 1). We noted an overall paucity of movement compared with other infants his age, although he appeared to be alert and interested in his environment.

[FIGURE 1 OMITTED]

Once the physical therapist moved to the other end of the treadmill and held him so that he was facing the therapist, the infant began taking steps immediately. The total number of steps increased gradually during this period (Fig. 4). Figure 5 shows that the type of step was initially variable, with alternating and single steps being the most prevalent step types, followed by parallel steps and then double steps. By the end of this phase, however, the infant more consistently took alternating steps, and the other step types were continuing to decline. Figure 6 shows that the infant's foot position was up on the toes more on the right at initial contact and that the proportion of toe-first initial contacts decreased bilaterally during the training phase.

[FIGURES 4, 5, 6 OMITTED]

Weeks 24-52: After treadmill Training The infant's motor development continued to lag behind his peers (Fig. 1), as he continued at or below the fifth percentile on the AIMS. (13) We tested him with the AIMS every 6 weeks during this period. Table 1 describes achievement of some typical motor milestones measured on the AIMS. (13) During this period, the infant's asymmetries appeared to decrease, although we still observed them in some activities. For example, if he needed to use his right hand for an activity, he would use it, but he usually used only his left hand.

Figure 4 shows that the infant's number of steps continued to increase, although at a slower rate. Furthermore, the infant took alternating steps almost exclusively (90% 100%) during the posttraining phase (Fig. 5). Asymmetries in foot position continued, with the infant on his toes more on the right side than the left side (Fig. 6). The proportion of steps with toe-first initial contact increased during the posttraining phase. Conversely, the proportion of heel-first or foot-flat initial contact decreased bilaterally during the posttraining phase.

Follow-up

The infant was seen in his home for a follow-up visit 3 months after we completed treadmill training, at 221/4 months of age (19 1/2 months CA). At that time, he could do all of the developmental skills on the AIMS. (13) His mother reported that he had been walking for approximately 2 months and that walking was his major form of mobility. His gait pattern was within normal limits for a child who had been walking for 2 months. He was able to stand up from the floor without UE support and was crawling up and down stairs. No asymmetry or atypical postures were noted. His mother reported that he continued to be less physically active than other children, most noticeably when she took him to the park or on play dates with other children his age. At about this time, the early intervention agency following the infant initiated speech therapy due to concerns about speech and language delays. The infant continued to remain alert and curious about his environment. Physical therapy was reduced to consultation as needed, provided in the home by the early intervention agency. Review of the medical records revealed that the child was discharged from physical therapy and NICU follow-up clinic at 23 months chronological age. All services through the early intervention agency were discontinued before the infant's third birthday because his development was age appropriate.

Discussion

Treadmill training has been incorporated into physical therapy intervention for children with cerebral palsy (5,6) and Down syndrome. (7) One purpose of this case report is to describe the feasibility of treadmill training for an infant at high risk for poor neuromotor development associated with preterm birth, intraventricular hemorrhage, bronchopulmonary dysplasia, and >28 days of oxygen use. The infant tolerated treadmill training well, as indicated by the clear majority of alert state ratings (state 4), (14) supporting the results of other studies that showed that infants usually enjoy stepping. (2-4) Furthermore, treadmill training was successfully learned and carried out by the infant's mother in the home. We did not detect any changes in stepping behavior that we could attribute to the mother, rather than the physical therapist, performing the training. Training at home saved time for the family and the physical therapist and demonstrates that treadmill training may be a useful home program. In the future, we will use a training log to track home-based treadmill training. Ulrich and colleagues (7) used a treadmill training home program in their study of infants with Down syndrome. They contended that parents of children with disabilities cope better with their situation if given activities to help their children's progress and that treadmill training fulfilled this need. (7) They also reported that treadmill training does not require a specially built treadmill, but that commercially available, full-size treadmills will work if they operate at slow enough speeds (20 m/s [0.5 mph]). (15) Richards and colleagues (5) recommended investigating the feasibility of home-based treadmill training because of difficulties transporting children to treatment centers as frequently as they believed training would be needed.

Walking has been identified as a highly important goal for parents of children with disabilities. (7) In addition, ambulation may be associated with enhanced cognitive and social development because the child is able to more around to interact with peers and explore the environment. (7) Studies with adults have shown that treadmill training is associated with improvements in overground walking. (16-18) Treadmill training provides task-specific practice (16-18) and improved gait parameters such as increased stride length and single-limb support period, (17) more symmetrical pattern, and more normal muscle activity in patients with stroke. (17-18) These parameters are related to balance and antigravity strength, which Thelen and Ulrich (2) identified as critical components for the development of independent walking.

Dynamic systems theory was the conceptual framework we used for treadmill training intervention and for choosing to initiate treadmill training before the infant had developed stepping patterns. We had not anticipated that the holding position would be an important aspect of task context, contributing to the infant's ability to produce steps. The infant did not take steps on the treadmill when he was held from behind, but he began producing steps immediately when the physical therapist moved to the opposite end of the treadmill and faced the infant. Thelen and Ulrich (2) hypothesized that the treadmill belt pulls the stance LE backward, putting a stretch on the hip flexors, which is a crucial component of treadmill stepping. The stance LE was not pulled back as far when our infant was held from behind, perhaps inhibiting adequate stretch of the hip flexors. We believe that changing the physical therapist's holding position enhanced the stretch on the stance LE, facilitating the stepping response. Prior to treadmill training for this infant, we placed 4 infants who were not at risk for neuromotor delays on a treadmill, holding them from both the back and the front. Unlike our infant, they produced steps regardless of how they were held; however, they seemed more content when they were held from the back so they could not see the physical therapist, and they had their mothers in front entertaining them. Future studies should determine if holding position is important for all infants who are at risk for neuromotor delays or if this was unique to our infant. The optimal amount of hip flexor stretch needed to facilitate alternating steps also should be ascertained in future studies.

A second purpose of this case report is to describe treadmill stepping patterns over time. We compared our infant's stepping patterns with those of infants in other treadmill stepping studies. Our infant's general development of stepping patterns was similar to that of infants born at term (2) and to that of infants born preterm at low risk for neuromotor complications. (3) Despite our infant's high-risk status, he produced steps on a moving treadmill during all trials once he was held from the front. Similar to other studies, he initially demonstrated multiple step types, but he showed a preference for alternating steps by 7 months CA, and he was taking alternating steps almost exclusively by 101/2 months CA. His pattern of alternating steps appears most similar to that of the "late-stepping" group of infants born preterm at low risk for neuromotor complications described by Davis and colleagues. (3) Although the "late steppers" produced few steps at 1 and 6 months CA, stepping increased sharply at 9 months CA, similar to the stepping pattern observed in our infant (Fig. 5). This stepping pattern is later than that of both infants born at full term and the "early-stepping" group of infants born preterm, who demonstrated the greatest number of alternating steps by 6 to 7 months of age (chronological age for full-term infants, CA for preterm infants). (2,3) Although later achievement of alternating treadmill steps may be due to individual variability, we cannot overlook the possibility that later stepping may be associated with pathophysiology or impairment related to prematurity. Thus, later stepping on the treadmill could be a predictor of future motor function, which should be investigated in future studies.

The total number of steps and the number of alternating steps increased faster during the training phase than during the posttraining phase. It is impossible, however, to determine if slower acquisition of steps posttraining was due to cessation of training because several other explanations are possible. This pattern roughly parallels that observed in other studies of infant stepping where the number of steps increased sharply and then leveled off, (2,3) so our infant may be have been reflecting a natural plateau in number of steps typical of all infants. Another explanation is that there is a ceiling effect in step number due to treadmill speed, making it impossible for the infant to take more steps at the speeds we used.

Figure 6 shows foot position at initial contact during training and posttraining phases of the study and clearly demonstrates that the right foot was positioned on the toes a higher proportion of steps and the left foot was flat a higher proportion. Furthermore, foot position seems to have been sensitive to treadmill training in this infant. When treadmill training was terminated, a consistent preference for heel-first or foot-flat positioning at initial contact was emerging. This preference continued for approximately 1 month following the termination of training, and then variability of foot position at initial contact increased sharply, with increased proportion of foot position on the toes. This finding is consistent with previous studies that have shown that children born preterm at high risk for poor developmental outcome had qualitatively different walking patterns, including altered foot position. (11,12) A similar, but less pronounced, pattern was seen in mid-stance foot position. We believe that treadmill training facilitated the heel-first and foot-flat patterns during the training phase.

Once training ended, however, the infant reverted to his former, less mature foot position at initial contact, suggesting that foot position was not yet stable. Treadmill training may have given the infant additional control over foot position that he was unable to maintain after training was discontinued. If this trend is confirmed with other children, treadmill training could prove to be a beneficial part of physical therapy for improving distal control of the LEs and should be continued until foot position is a stable pattern, possibly until the child walks independently. This finding is also interesting because we observed clinically that the infant used his right extremities less than the left extremities during functional movement. We theorized that this might have been related to the intraventricular hemorrhage and ventriculomegaly being on the left side of his brain and that symmetry of foot position during treadmill stepping may be an indicator of neuromotor status.

The infant's motor development remained at or below the fifth percentile on the AIMS (13) until the follow-up visit 3 months after the end of the study. At that time, he had reached the test ceiling. The infant walked independently at approximately 17 months CA and used walking as his primary means of locomotion by 191/4 months CA. Thus, this infant walked independently approximately 1 month earlier than infants identified as having delayed walking. (8, 10) A study with a control group is needed to determine if treadmill training facilitates earlier walking in children at high risk for neuromotor delays associated with prematurity and related complications, as it did in children with Down syndrome. (7)

Conclusions

This case report shows that treadmill training is feasible in an infant born preterm at high risk for neuromotor disabilities, which supports the work of Ulrich and colleagues' work showing that family members can carry out training programs in the home. (7) This report raises many questions, such as the ideal age to begin treadmill training, appropriate frequency and duration of training, and the most time- and cost-effective way to provide treadmill training. Studies of infants at risk for neuromotor disabilities are needed to determine if treadmill training facilitates earlier independent ambulation and better foot position and if there is a relationship between treadmill training and long-term developmental outcome.

Table 1.

Age of Achievement of Developmental Milestones

From Alberta Infant Motor Scale (13)

Developmental Milestone            Chronological Age

Initial examination
  Lifts, maintains head
  briefly in sitting position      7 months, 28 days
  Chin tuck, hands to
  midline in supine position       7 months, 28 days
  Unsustained head raising
  in prone position                7 months, 28 days

First 6 weeks
  Taking weight on legs in
  supported standing position      9 months, 8 days
  Holding head at 90 [degree]
  in prone position                9 months, 8 days
  Momentary sitting with upper
  extremity support
  (prop sitting)                   9 months, 8 days

Treadmill training phase
  Prone on elbows                  10 months, 19 days
  Momentary sitting without
  upper-extremity support          10 months, 19 days
  Hand-to-feet play in
  supine position                  10 months, 19 days
  Prone: playing on extended
  arms, reaching, pivoting         11 months, 26 days
  Independent sitting without
  upper-extremity support          1 year, 21 days

Post-treadmill training phase
  Rolling from supine
  position to prone position       1 year, 1 month, 28 days
  Maintains 4-point
  kneeling position                1 year, 1 month, 28 days
  Creeping on hands and knees      1 year, 3 months, 1 day
  Transition from sitting
  position to 4-point
  kneeling position                1 year, 4 months, 16 days
  Pull to standing position        1 year, 4 months, 16 days
  Cruising along the furniture     1 year, 4 months, 16 days
  Stand alone                      1 year, 5 months, 29 days
  Early stepping                   1 year, 7 months, 3 days
  Walk alone                       1 year, 8 months (a)

Developmental Milestone            Corrected Age

Initial examination
  Lifts, maintains head
  briefly in sitting position      5 months, 7 days
  Chin tuck, hands to
  midline in supine position       5 months, 7 days
  Unsustained head raising
  in prone position                5 months, 7 days

First 6 weeks
  Taking weight on legs in
  supported standing position      6 months, 17 days
  Holding head at 90 [degree]
  in prone position                6 months, 17 days
  Momentary sitting with upper
  extremity support
  (prop sitting)                   6 months, 17 days

Treadmill training phase
  Prone on elbows                  7 months, 28 days
  Momentary sitting without
  upper-extremity support          7 months, 28 days
  Hand-to-feet play in
  supine position                  7 months, 28 days
  Prone: playing on extended
  arms, reaching, pivoting         9 months, 5 days
  Independent sitting without
  upper-extremity support          10 months, 0 days

Post-treadmill training phase
  Rolling from supine
  position to prone position       11 months, 7 days
  Maintains 4-point
  kneeling position                11 months, 7 days
  Creeping on hands and knees      1 year, 10 days
  Transition from sitting
  position to 4-point
  kneeling position                1 year, 1 month, 25 days
  Pull to standing position        1 year, 1 month, 25 days
  Cruising along the furniture     1 year, 1 month, 25 days
  Stand alone                      1 year, 3 months, 8 days
  Early stepping                   1 year, 4 months, 12 days
  Walk alone                       1 year, 5 months, 9 days

(a) By mother's report.

References

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(2) Thelen E, Ulrich BD. Hidden skills: a dynamic systems analysis of treadmill stepping during the first year. Monogr Soc Res Child Dev. 1991;56(serial no. 223):1-97.

(3) Davis DW, Thelen E, Keck J. Treadmill stepping in infants born prematurely. Early Hum Dev. 1994;39:211-223.

(4) Vereijken B, Thelen E. Training infant treadmill stepping: the role of individual pattern stability. Dev Psychobiol. 1997;30:89-102.

(5) Richards CL, Malouin F, Dumas F, et al. Early and intensive treadmill locomotor training for young children with cerebral palsy: a feasibility study. Pediatric Physical Therapy. 1997;9:158-165.

(6) Schindl MR, Forstner C, Kern H, Hesse S. Treadmill training with partial body weight support in nonambulatory patients with cerebral palsy. Arch Phys Med Rehabil. 2000;81:301-306.

(7) Ulrich DA, Ulrich BD, Angulo-Kinzler RM, Yun J. Treadmill training of infants with Down syndrome: evidence-based developmental outcomes. Pediatrics. 2001;108(5):E84.

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AW Bodkin, PT, MS, PCS, is Instructor, Rehabilitation Medicine, University of Colorado Health Sciences Center, and Physical Therapist, Center For Gait and Movement Analysis, Box A036/B476, Denver, CO, 80262 ([e-mail]). Address all correspondence to Ms Bodkin.

RS Baxter, PT, MS, is Physical Therapist, Rapid City Regional Hospital, Rapid City, SD.

CB Heriza, PT, EdD, is Director, Physical Therapy Program and Assistant Dean, Allied Health, University of Colorado Health Sciences Center, Denver, Colo.

Dr Heriza provided concept/idea/project design, fund procurement, facilities/equipment, and institutional liaisons. Ms Bodkin provided writing, project management, and the subject. Ms Bodkin and Ms Baxter provided data analysis. All authors provided data collection and consultation (including review of manuscript before submission).

This project was approved by the Colorado Multiple Institutional Review Board.

Partial results of this work were presented at the Combined Sections Meeting of the American Physical Therapy Association, February 3--7, 1999, Seattle, Wash; the International Conference of Infant Studies, July 16-19, 2000, Brighton, England; and the University of Colorado Health Sciences Center Student Research Forum, October 30, 2000, Denver, Colo.

This work was partially supported by grant 6773MC00011 from the Maternal and Child Health Bureau awarded to Dr Heriza.

* Panasonic Broadcast & Television Systems Co, One Panasonic Way, Secaurus, NJ 07094,

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