Sally D. Lark

Joint torques and dynamic joint stiffness in elderly and young men during stepping down

OBJECTIVE To compare the joint torque pattern and dynamic joint stiffness at the knee and ankle in elderly and young men during stepping down. BACKGROUND Adequate joint stiffness is critical during the single support phase to control forward and downward body momentum. DESIGN Six active elderly men (mean 67.7) and six young men (mean 23.6) of similar body mass and height, were filmed stepping down from one force platform to another. Repeated trials were undertaken at three different step heights (200, 250, and 300 mm). METHOD Joint torques were determined for the ankle and knee of the support limb throughout the single support phase. The gradient of the joint torque-angle graph was calculated to define dynamic joint stiffness of the ankle and knee in two phases; (I) from initiation of movement until heel-off of the supporting limb, and (II) from heel-off of the supporting limb to contra-limb touch down. RESULTS Maximum ankle torque values were lower in the elderly and occurred at a larger dorsiflexion angle (P<0.05). Knee torque patterns were similar in both groups. Phase I ankle stiffness was significantly less in the elderly (4.0-5.2 Nm/ degrees ) at all step heights compared to the young (7.6 - 8.7 Nm/ degrees ). In both groups ankle stiffness in Phase II increased with step height, while knee joint stiffness decreased. CONCLUSIONS The different torque pattern and lower dynamic ankle stiffness in the elderly, particularly for Phase I, suggested an altered control strategy. These findings highlight the importance of dynamic ankle joint stiffness in stepping down. RELEVANCE Understanding how the elderly step down may be important in developing strategies to prevent falls.

Cervical range of motion and proprioception in rugby players versus non-rugby players

Abstract In this study, we examined the effects of number of years of playing rugby on neck function. Active cervical spine range of motion and proprioception were assessed in 14 non-rugby-playing but trained sportsmen (mean age 28 years, s = 7) and 46 rugby players (26 rugby forwards: mean age 26 years, s = 5; mean years played 14 years; 20 backs: mean age 24 years, s = 5; mean years played 14 years). Active cervical range of motion in flexion, extension, left and right lateral flexion, plus left and right rotation were measured using a cervical range of motion device. The ability to reposition the head in a central position with eyes closed was taken as a measure of proprioception. Results show that rugby forwards generally had the least active cervical range of motion, particularly neck extension (forwards, 43°; backs, 55°; controls, 58°), with the decrement correlating with the number of years played. In addition, repositioning was significantly worse in rugby players after neck extension than non-rugby players (6° vs. 3°). The active cervical range of motion of rugby forwards is similar to that of whiplash patients, suggesting that participation in rugby can have an effect on neck range of motion that is equivalent to chronic disability. Reduced active cervical range of motion could also increase the likelihood of injury and exacerbate age-related neck problems.

Validity of a Functional Dynamic Walking Test for the Elderly

OBJECTIVE To determine the validity of a safe, quick, and simple method of measuring dynamic balance in the elderly during gait called the parallel walk test. DESIGN Control study. SETTING Outpatient clinic, community. PARTICIPANTS Twenty-seven elderly fallers (age 82+/-6y) registered at a falls clinic and 34 elderly nonfallers (age 76+/-7y) were recruited to this study based on Mini Mental State Examination and Barthel Index scores. INTERVENTIONS Subjects were timed as they walked 6m between 2 parallel lines on the floor at 3 different widths (20, 30.5, 38cm) in their own footwear. They were scored for foot placement on the line (1 point) or outside the lines (2 points). Participants also performed a timed 6-m tandem walk test, a 30-second tandem stance, and a 30-second parallel stance. MAIN OUTCOME MEASURES Scores and time to complete the parallel walk test and tandem walk test along with the time of standing for tandem and parallel stance. Validity coefficients were calculated for the sensitivity and specificity of the parallel walk test. RESULTS All subjects completed the parallel walk test, but few attempted and completed the tandem walk test. The fallers had significantly greater scores at 20 and 30.5cm and took significantly longer to complete the 6m at all widths. The 20-cm width was most discriminatory. The parallel walk test showed a significant correlation with the tandem stance. CONCLUSIONS All subjects attempted and completed the parallel walk test but not the tandem walk test. The time to completion and scoring accurately measures dynamic balance during gait in elderly fallers. The parallel walk test could be a useful tool in the clinical setting for assessing balance in gait pre- and postintervention.

Mass affects lower extremity muscle activity patterns in children's gait

Overweight children demonstrate biomechanical differences during gait; however it is not known if these differences occur within active or passive tissue. The purpose of this study was to examine differences in lower extremity muscle activation patterns of children with different body mass during three walking speeds. Twenty children (8-12 years) were recruited and classified as overweight (OW), normal-weight (NW), or underweight (UW). Electromyography was recorded for vastus lateralis, semitendinosus, gastrocnemius, and tibialis anterior while participants walked on a treadmill at slow (SP), self-selected (SSP), and fast (FP) speeds. Differences in group and walking speed were analyzed for duration of muscle activation (presented as a percentage of stride, stance, or swing phases). Compared to OW, UW experienced greater duration of vastus lateralis and tibialis anterior activation during the swing phase. OW had greater duration of gastrocnemius activation during stride than UW. Increased walking speed resulted in greater duration of vastus lateralis activation for all groups. NW also exhibited greater duration of tibialis anterior activation at faster walking speeds. During FP, OW had greater duration of gastrocnemius activity during stance, but lower duration during swing. These findings are consistent with the idea that children with greater mass adopt a more passive gait strategy during swing to maximize energy recovery. Increased duration of gastrocnemius activity during stance also provides greater stability and stronger propulsion, which corroborates previous research. These findings help to understand the neuromuscular mechanisms associated with previous biomechanical findings in childrens gait.

The effects of a single game of rugby on active cervical range of motion.

Abstract The cumulative effect of playing rugby over many years decreases active cervical range of motion, especially in the forwards. This in itself should influence long-term neck care; however, it leaves the important question of how noticeable the acute effects of active cervical range of motion are following a single game. The active cervical range of motion was measured in 21 elite rugby players (mean age 24.4 ± 4.3 years; average professional career of 7 ± 3.4 years) before and after a single game of rugby at the start of the season. The active cervical range of motion was recorded in flexion, extension, left and right side flexion, plus left and right rotation using a cervical range of motion device. The results show generally decreased active cervical range of motion from before to after a game independent of position played. Rugby backs had significantly (P < 0.05) reduced active cervical range of motion in flexion, while forwards were affected in extension and left lateral flexion (P < 0.05). These results highlight that a single game of rugby can reduce functional capacity of the neck (active cervical range of motion), and the affected neck movement appears to be related to the role of positional play. The authors suggest that neck training and muscle damage repair should be an important part of a rugby players post-game recovery to limit the reduction in functional capacity.

The effects of a rugby playing season on cervical range of motion

Abstract Rugby players have a reduced active cervical range of motion (ACROM) mid-season compared with age-matched controls. This is most evident in rugby forwards, who have ACROM similar to patients with acute whiplash. This study aims to show if the change in ACROM over an entire rugby season (pre-, mid-, and end of season) shows a pattern of decline. A cross-sectional study of 22 rugby players (11 backs aged 24.9 ± 1.3 years; 11 forwards aged 24.5 ± 1.1 years) from elite English Premiership clubs had their cervical range of motion measured for flexion, extension, left and right side flexion, plus left and right rotation with a cervical range of motion device. The percentage change between start to mid-season, mid- to end of season, and start to end of season were calculated. Group means were compared for absolute ACROM (degrees) and percentage change over the season. The percentage change indicated a decrease in ACROM over the rugby playing season, with most of the decrement occurring in the second half of the season. Most of the relative change was observed in right lateral flexion, while rotation did not change significantly. In conclusion, ACROM declines throughout the playing season, which requires attention in terms of training and rehabilitation.

A randomized controlled trial to assess the effect of self-paced walking on task-specific anxiety in cardiac rehabilitation patients.

PURPOSE: Cardiac rehabilitation can reduce overall anxiety. However, task-specific anxiety is yet to be investigated in the cardiac patient. This study investigates the effect of an outdoor walking intervention (WI) in alleviating the high degree of task-specific anxiety in cardiac patients. METHODS: Participants (N = 22, mean age ± SD = 62.0 ± 10.8 years, 9 women), who had experienced a cardiac event and exhibited a moderate to high level of anxiety for outdoor walking (anxiety score ≥ 7 on a modified version of the Hospital Anxiety and Depression Scale), were initially assessed during an incremental shuttle walk test and a self-paced 1-mile walk. Heart rate and the ratings of perceived exertion were monitored during both tests. Participants also completed an exercise self-efficacy (ESE) questionnaire. Following this, participants were randomized to either a 3 sessions per week, 4 weeks, self-paced WI on a predetermined variable topographic course, or to a control group (CG; 30-minute stationary cycling, 3 sessions per week for 4 weeks). Identical assessments (Incremental Shuttle Walk Test, Self-Paced 1-Mile Walk, Hospital Anxiety and Depression Scale, ESE) were used postintervention. The 2 groups were compared for anxiety, ESE, and fitness by analysis of variance. RESULT: The WI group exhibited a significantly greater decrease in task-specific anxiety (51%; P < .01), increased self-efficacy (6.6%; P < .001) and improved fitness (P < .05) in comparison with CG. CONCLUSION: This study demonstrated that task familiarization reduced the task-specific anxiety associated with outdoor walking in cardiac patients and, as such, may help in changing exercise behavior patterns in patients undergoing cardiac rehabilitation.

Effect of early exercise engagement on arterial stiffness in patients diagnosed with a transient ischaemic attack

This study investigated the effects of regular exercise participation on common carotid artery stiffness in patients recently diagnosed with transient ischaemic attack (TIA). A total of 21 male and 4 female participants (mean±s.d.; 66±12 years, 1.72±0.07 m, 85.5±12.4 kg), recruited within 2 weeks of TIA diagnosis, completed a risk stratification assessment (including fasting blood glucose, cholesterol), a health history questionnaire and underwent measures of arterial stiffness (compliance and distensibility). Participants were then randomized to either an exercise (EX; 8-week intervention) or a usual-care control (CON) condition. Identical measures were obtained post intervention. Within-subject, repeated measures analysis of variance, with Condition as the between-subject factor (EX and CON), was used to assess measures of arterial stiffness at the baseline and postintervention assessment. Results revealed a significant interaction whereby an increase in compliance (0.71±0.24 vs 0.83±0.28 mm2 kPa−1, P=0.048, partial η2=0.159) and distensibility (15.98±5.95 vs 19.49±6.60 10−3 kPa−1, P=0.023, partial η2=0.204) was observed for EX but not for CON. The present study has demonstrated that engagement in exercise soon after TIA diagnosis leads to improved large artery health. These improvements in vascular health may reduce the risk of an ensuing or recurring cardio- or cerebrovascular event.

Reliability of the parallel walk test for the elderly.

OBJECTIVE To determine interrater agreement and test-retest reliability of the parallel walk test (PWT), a simple method of measuring dynamic balance in the elderly during gait. DESIGN Cohort study. SETTING Outpatient clinic. PARTICIPANTS Elderly fallers (N=34; mean ± SD age, 81.3±5.4y) registered at a falls clinic participated in this study based on Mini-Mental State Examination and Barthel Index scores. INTERVENTIONS Subjects were timed as they walked 6m between 2 parallel lines on the floor at 3 different widths (20, 30.5, 38cm) wearing their own footwear. They were scored for foot placement on (1 point) or outside the lines (2 points) by 2 separate raters. Fifteen subjects were retested 1 week later. MAIN OUTCOME MEASURES Footfall score and time to complete the PWT. Intraclass correlation coefficients (ICCs) and 95% limits of agreement were calculated for interrater and test-retest reliability. RESULTS For widths of 20, 30.5, and 38cm, interrater reliability ICC range was .93 to .99 and test-retest ICC range was .63 to .90. CONCLUSIONS The PWT was implemented easily by 2 raters with a high degree of interrater reliability. Test-retest reliability was not as high, possibly because of the high susceptibility of variation from 1 week to the next for frail elderly subjects. The 20- and 30.5-cm widths are recommended for future use of the PWT.

Pre-adolescent cardio-metabolic associations and correlates: PACMAC methodology and study protocol

Introduction Although cardiovascular disease is typically associated with middle or old age, the atherosclerotic process often initiates early in childhood. The process of atherosclerosis appears to be occurring at an increasing rate, even in pre-adolescents, and has been linked to the childhood obesity epidemic. This study will investigate the relationships between obesity, lifestyle behaviours and cardiometabolic health in pre-pubescent children aged 8–10 years, and investigates whether there are differences in the correlates of cardiometabolic health between Māori and Caucasian children. Details of the methodological aspects of recruitment, inclusion/exclusion criteria, assessments, statistical analyses, dissemination of findings and anticipated impact are described. Methods and analysis Phase 1: a cross-sectional study design will be used to investigate relationships between obesity, lifestyle behaviours (nutrition, physical activity/fitness, sleep behaviour, psychosocial influences) and cardiometabolic health in a sample of 400 pre-pubescent (8–10 years old) children. Phase 2: in a subgroup (50 Caucasian, 50 Māori children), additional measurements of cardiometabolic health and lifestyle behaviours will be obtained to provide objective and detailed data. General linear models and logistic regression will be used to investigate the strongest correlate of (1) fatness; (2) physical activity; (3) nutritional behaviours and (4) cardiometabolic health. Ethics and dissemination Ethical approval will be obtained from the New Zealand Health and Disabilities Ethics Committee. The findings from this study will elucidate targets for decreasing obesity and improving cardiometabolic health among preadolescent children in New Zealand. The aim is to ensure an immediate impact by disseminating these findings in an applicable manner via popular media and traditional academic forums. Most importantly, results from the study will be disseminated to participating schools and relevant Māori health entities.