The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s−1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion. We measured the electromyographic activity of the soleus, medial and lateral gastrocnemii just after the perturbation to evaluate the triceps surae stretch reflex. Similar perturbations were also delivered at rest. Our results showed that the stretch reflex was suppressed during the swing phase of running, except in late swing where a late reflex response was observed. At rest, all triceps surae muscles showed an early reflex response to stretch. Our findings suggest that the triceps surae short/medium-latency stretch reflex cannot be evoked during swing phase and thus cannot contribute to the control of the locomotor pattern after aperturbation during this phase.
Mikael Scohier, Dominique De Jaeger and Benedicte Schepens
Andresa R. Marinho-Buzelli, Ana Maria Forti Barela, Jose Angelo Barela, Melissa Leandro Celestino, Milos R. Popovic and Mary Verrier
Aquatic therapies are used to restore step initiation in people with locomotor disabilities. However, there is lack of evidence of underlining mechanisms of gait initiation in water. We investigated center of pressure (CoP), vertical and anterior-posterior impulse forces, and kinematics of the first step performed in water in comparison with overground walking. The peaks of anticipatory postural adjustment (APA) and the sections of CoP trajectories were longer in water than on land. Impulse forces were increased in water compared with land. Range of motion (ROM) of ankle joint increased in water while knee joint ROM did not change. We suggest that the aquatic environment may facilitate gait initiation training by allowing a longer step execution with greater stimuli and imposed resistance for the phases of gait initiation.
Megan A. Kirk and Ryan E. Rhodes
Preschoolers with developmental delay (DD) are at risk for poor fundamental movement skills (FMS), but a paucity of early FMS interventions exist. The purpose of this review was to critically appraise the existing interventions to establish direction for future trials targeting preschoolers with DD. A total of 11 studies met the inclusion criteria. Major findings were summarized based on common subtopics of overall intervention effect, locomotor skill outcomes, object-control outcomes, and gender differences. Trials ranged from 8 to 24 weeks and offered 540–1700 min of instruction. The majority of trials (n = 9) significantly improved FMS of preschoolers with DD, with a large intervention effect (η2 = 0.57–0.85). This review supports the utility of interventions to improve FMS of preschoolers with DD. Future researchers are encouraged to include more robust designs, a theoretical framework, and involvement of parents and teachers in the delivery of the intervention.
Amelia Mays Woods, Kim C. Graber, David Newman Daum and Chris Gentry
This study examined physical activity (PA) variables related to recess PA patterns of kindergarten, first and second grade children, and the social preferences and individuals influencing their PA. Data collected (N = 147) used the System of Observing Children’s Activity and Relationships during Play (SOCARP) instrument. Children were interviewed. Kindergarten boys spent a significantly higher percentage of time in MVPA (t = 3.137, d = .96, p < .008). Kindergarten girls spent significantly more time standing (t = 3.548, d = 1.07, p < .008). Second grade boys spent a significantly (t = 4.44, d = 1.98, p < .0125) more time in sport activities. Second grade girls spent significantly more time in sedentary (t = 4.399, d = 1.11, p < .0125) and locomotor (t = 3.533, d = .899, p < .0125) activities. Participants articulated the prominence of friends, engaging in games/activities, and playing on the playground equipment.
Lauriece L. Zittel and Jeffrey A. McCubbin
The purpose of this study was to investigate the effect of an integrated physical education setting on the motor performance of preschool children with developmental delays. Subjects participated in segregated and integrated physical education classes and were observed practicing locomotor and object control skills. The quality of performance was analyzed to determine the number of critical elements present and the level of teacher or peer prompt required to initiate and complete each performance. A single-subject reversal design (A-B-A-B) was used. Four children with developmental delays were filmed within an 8-week school schedule while practicing two fundamental gross motor skills during segregated and integrated conditions. The results provide evidence that children with developmental delays are able to maintain their level of gross motor skill and independence within an integrated physical education setting. Although day-to-day variability was calculated for each subject, overall skill level remained stable and level of independence was not compromised in the integrated setting.
Ellen M. Kowalski and Claudine Sherrill
This study examined the effects of model type and verbal rehearsal strategy in relation to motor sequencing of boys with learning disabilities (LD). Eighty boys, ages 7 and 8 years, were exposed to four experimental conditions in a 2 × 2 (Model × Verbal Rehearsal Strategy) design. Subjects were randomly assigned to one of four groups: (a) visual-silent model/verbal rehearsal, (b) visual-verbal model/verbal rehearsal, (c) visual-silent model/ no verbal rehearsal, and (d) visual-verbal model/ no verbal rehearsal. The four groups were statistically equal on measures of age, IQ, behavior, learner modality preference, and motor proficiency. Data collected for experimental analysis were generated by the Motor Sequencing Test which measured the ability to model seven locomotor tasks in the correct order. Results revealed that the boys with LD performed significantly better on the motor sequencing test when trained in verbal rehearsal strategy. However, results indicated no significant difference in motor sequencing under visual-silent and visual-verbal model conditions.
Jin H. Yan and John H. Downing
Tai Chi, an ancieni form of Chinese fitness exercise, affords its participants a variety of physical and psychological benefits. Research has suggested that individuals engaging in Tai Chi exercises improve cardiovascular fitness and motor control while reducing stress, anxiety and depression. Tai Chi is particularly suitable for seniors, who are often at risk for a variety of problems associated with aging (e.g.. arthritis, neurological dysfunction, and general decline of balance, coordination, and locomotor function). Because of its self-paced. nonstressful, and noncompetitive nature, and its ability to afford economy of lime, space, and equipment, Tai Chi presents an effective, functional alternative exercise form for the senior adult population. This article presents the background of Tai Chi practice and introduces several key elements and suggestions for teaching Tai Chi to senior participants. Finally, some selected resources for Tai Chi practice are listed.
Jason D. Vescovi and Devon H. Frayne
To examine locomotor demands and metabolic-power characteristics of National Collegiate Athletic Association (NCAA) field hockey matches.
Using a cross-sectional design, global positioning system (GPS) technology tracked Division I field hockey players from 6 teams during 1 regular-season match (68 player observations). An ANOVA compared locomotor demands and metabolic-power characteristics among positions. Paired t tests compared dependent variables between halves.
Defenders played 5−6 min more than midfielders, whereas midfielders played 6−7 min more than forwards. Defenders covered less relative distance (98 m/min) than forwards and midfielders (110−111 m/min), as well as more low-intensity running than forwards and less high-intensity running than midfielders. Lower mean metabolic power (9.3 W/kg) was observed for defenders than forwards and midfielders (10.4 W/kg). There was no difference in playing time between halves; however, all 3 positions had a reduction in relative distance (7−9%) and mean metabolic power (8−9%) during the second half.
Despite more playing time, defenders covered less relative distance and had lower mean metabolic power than other positions. Moderate-intensity, high-intensity, and sprint distance were similar between positions, highlighting the greater relative demands on forwards because they tended to have the least amount of playing time. The reduction of key metrics during the second half was similar among positions and warrants further investigation. These initial results can be used to design position-specific drills or create small-sided games that replicate match demands for NCAA athletes, thus helping establish strategies for developing physiological ability of players at this level.
Atsumichi Tachibana, Futoshi Mori, Carol A. Boliek, Katsumi Nakajima, Chijiko Takasu and Shigemi Mori
This study investigated developmental aspects of the acquisition of operant-trained bipedal (Bp) standing and Bp walking in the normally quadrupedal (Qp) juvenile Japanese monkey (M. fuscata). Four male monkeys (age: 1.6 to 2.4 years, body weight: 3.3 to 4.6 kg) were initially operantly trained to stand upright on a smooth floor and a stationary treadmill belt (width = 60 cm, walking length = 150 cm). They were then trained to walk bipedally on the moving treadmill belt (speed: 0.4–0.7 m/s). A regular training program (5 days/week; 30–60 min/day) was given to each monkey for the first 40 to 60 days, followed by less intensive training. After the beginning of locomotor training, upright postural stability and Bp walking capability were assessed kinematically for 592, 534, 526, and 537 days on monkeys A, B, C, and D, respectively. Left side- and back-views of the walking monkey were photographed (10 frames/s) and videotaped (250 frames/s). Stick figures of the head, body, and hindlimbs were drawn with reference to ink-marks positioned in front of the ear and over the pivot points of hindlimb joints. All kinematic data were digitized and analyzed using image-analyzing software. After sufficient physical growth and locomotor training, all the monkeys gradually acquired: (a) a more upright and a more stable posture with a constant body axis orientation during Bp locomotion; (b) a more stable and a stronger functional coupling between the body and hindlimb movements with a less anterior (A)-posterior (P) fluctuation of a body axis; (c) a smaller leftward (Lt)-rightward (Rt) displacement of the midline pelvic position, allowing the monkey to walk along a straight course; (d) a more coordinated relationship among hip-knee, knee-ankle, and ankle-metatarsophalangeal (MTP) joints; and finally (e) the acquisition of well-coordinated Bp walking even at high treadmill belt speeds up to 1.5 m/s. All of these results demonstrated the capability of the physically developing monkey to integrate the neural and musculoskeletal mechanisms required for sufficient coordination of upper (head, neck, trunk) and lower (hindlimbs) motor segments so that Bp standing and Bp walking could be elaborated.
Moeko Ueno, Ichiro Uchiyama, Joseph J. Campos, David I. Anderson, Minxuan He and Audun Dahl
Infants show a dramatic shift in postural and emotional responsiveness to peripheral lamellar optic flow (PLOF) following crawling onset. The present study used a novel virtual moving room to assess postural compensation of the shoulders backward and upward and heart rate acceleration to PLOF specifying a sudden horizontal forward translation and a sudden descent down a steep slope in an infinitely long virtual tunnel. No motion control conditions were also included. Participants were 53 8.5-month-old infants: 25 prelocomotors and 28 hands-and-knees crawlers. The primary findings were that crawling infants showed directionally appropriate postural compensation in the two tunnel motion conditions, whereas prelocomotor infants were minimally responsive in both conditions. Similarly, prelocomotor infants showed nonsignificant changes in heart rate acceleration in the tunnel motion conditions, whereas crawling infants showed significantly higher heart rate acceleration in the descent condition than in the descent control condition, and in the descent condition than in the horizontal translation condition. These findings highlight the important role played by locomotor experience in the development of the visual control of posture and in emotional reactions to a sudden optically specified drop. The virtual moving room is a promising paradigm for exploring the development of perception–action coupling.