Lynda Norton

Evidence for secular trends in children’s physical activity behaviour

It is not clear whether the global increase in weight problems in children is the result of excessive energy intake or decreasing energy expenditure. Methodological limitations have made it difficult to analyse. There is evidence that at least part of the problem may lie with increasing energy consumption, but it is important to examine the other side of the energy equation also. However, it is not possible to conclusively describe physical activity trends because of the absence of suitable baseline data. One solution is to summate all available evidence in as many areas of daily activities as possible and then draw tentative conclusions. This review summarises available trend data on direct representations of physical activity in a range of contexts, together with indirect measures such as sedentariness, fitness, and attitudes. The conclusions drawn are: physical activity in clearly defined contexts such as active transport, school physical education, and organised sports is declining in many countries; young people would like to be active but are often constrained by external factors such as school policy or curricula, parental rules in relation to safety and convenience, and physical environmental factors.

Position statement on physical activity and exercise intensity terminology.

The terminology used for monitoring and promoting physical activity and exercise among health and fitness professionals varies considerably. There is a large array of descriptor terms reported in the literature and used in day-to-day practice and this inconsistency can be confusing for clients and practitioners alike. The variation in terminology also makes it difficult to track changes in activity patterns over time and across studies. There are also a range of objective and relative intensity cut-offs used to describe the same intensity descriptors. This position statement addresses the question of standardisation of physical activity and exercise intensity terminology and makes recommendations that should assist those undertaking research and prescribing physical activity/exercise as well as those clients who are receiving professional guidance.

Glucose control, organ failure, and mortality in pediatric intensive care

Objective: In ventilated children, to determine the prevalence of hyperglycemia, establish whether it is associated with organ failure, and document glycemic control practices in Australasian pediatric intensive care units (PICUs). Design: Prospective inception cohort study. Setting: All nine specialist PICUs in Australia and New Zealand. Patients: Children ventilated >12 hrs excluding those with diabetic ketoacidosis, on home ventilation, undergoing active cardiopulmonary resuscitation on admission, or with do-not-resuscitate orders. Interventions: None. Measurements and Main Results: All blood glucose measurements for up to 14 days, clinical and laboratory values needed to calculate Paediatric Logistic Organ Dysfunction (PELOD) scores, and insulin use were recorded in 409 patients. Fifty percent of glucose measurements were >6.1 mmol/L, with 89% of patients having peak values >6.1 mmol/L. The median time to peak blood glucose was 7 hrs. Hyperglycemia was defined by area under the glucose-time curve >6.1 mmol/L above the sample median. Thirteen percent of hyperglycemic subjects died vs. 3% of nonhyperglycemic subjects. There was an independent association between hyperglycemia and a PELOD score ≥10 (odds ratio 3.41, 95% confidence interval 1.91–6.10) and death (odds ratio 3.31, 95% confidence interval 1.26–7.7). Early hyperglycemia, defined using only glucose data in the first 48 hrs, was also associated with these outcomes but not with PELOD ≥10 after day 2 or with worsening PELOD after day 1. Five percent of patients received insulin. Conclusions: Hyperglycemia is common in PICUs, occurs early, and is independently associated with organ failure and death. However, early hyperglycemia is not associated with later or worsening organ failure. Australasian PICUs seldom use insulin.

A comparison of two short-term intensive physical activity interventions: methodological considerations

BackgroundIncreases in chronic illness due to sedentary lifestyles and poor metabolic fitness have led to numerous intervention strategies to promote physical activity (PA). This paper describes the methodological strategies of two short-term PA interventions. Outcome measures reported are PA adherence and compliance rates during the intervention and at 3, 6 and 12-month follow-up.MethodsThe 40-day interventions were: a pedometer-based walking program (n = 251) and a group-based intensive program (n = 148). There was also an active control group (n = 135). Intervention subjects were prescribed PA each day and required to record all activity sessions (pedometer steps or energy expenditure from heart rate monitors).ResultsCompliance (≥ 150 min/wk PA) was highest post-intervention (81.1% and 64.5% for the group and pedometer subjects, respectively) and then progressively decreased across the 12-month follow-up period (final compliance rates were 53.5% and 46.6%, respectively) although they remained significantly higher than pre-intervention rates (zero %). There was significantly higher adherence to 6 months (75.0% and 64.9%), and compliance to 3 months (64.9% and 51.0%), for group versus pedometer subjects. The active control group maintained the highest adherence and compliance rates across the study.ConclusionsThe group-based program resulted in higher adherence and compliance rates post-intervention although both types of interventions showed long-term effectiveness to increase activity patterns.

Impact of stretching on the performance and injury risk of long-distance runners.

ABSTRACT Stretching, either prior to exercise or at the end, or both, is typically carried out by all individuals undertaking sporting activity whether they be elite or recreational athletes. The many forms of stretching available to the athlete, either passive or active, have long been thought to improve performance, decrease injury and generally be advantageous to the athlete. This review examines the current state of the literature and evaluates what athletes can and should do with respect to this controversial topic.

Effects of Short-Term Physical Activity Interventions on Simple and Choice Response Times

Objective. Response time (RT) is important for health and human performance and provides insight into cognitive processes. It deteriorates with age, is associated with chronic physical activity (PA), and improves with PA interventions. We investigated associations between the amount and type of PA undertaken and the rate of change in RT for low-active adults across the age range 18–63 yr. Methods. Insufficiently active adults were assigned to either a walking (n = 263) or higher-intensity (n = 380) exercise program conducted over 40 days. Active controls were also recruited (n = 135). Simple response time (SRT) and choice response time (CRT) were measured before and after the intervention and at 3-, 6-, and 12-month follow-up. Results. SRT and CRT slowed across the age range; however, habitually active participants at baseline had significantly faster CRT (p < 0.05). The interventions increased weekly PA with corresponding increases in physical fitness. These changes were mirrored in faster CRT across the study for both intervention groups (p < 0.05). No changes were found for SRT. Conclusions. Both PA interventions resulted in improvements in CRT among adults starting from a low activity base. These improvements were relatively rapid and occurred in both interventions despite large differences in exercise volume, type, and intensity. There were no effects on SRT in either intervention.

Adherence, Compliance, and Health Risk Factor Changes following Short-Term Physical Activity Interventions

Background. Low physical activity (PA) levels are associated with poor health risk factor profiles. Intervention strategies to increase PA and quantify the rate and magnitude of change in risk factors are important. Methods. Interventions were conducted over 40 days to increase PA in 736 insufficiently active (<150 min/wk PA) participants using either a pedometer or instructor-led group protocol. There were a further 135 active participants as controls. Major cardiovascular and metabolic risk factors, including fitness parameters, were measured before and after intervention. Results. Adherence to the interventions was higher for the group versus pedometer participants (87.1% versus 79.8%) and compliance rates for achieving sufficient levels of PA (≥150 min/wk) were also higher for the group participants (95.8% versus 77.6%). Total weekly PA patterns increased by 300 and 435 minutes, for the pedometer and group participants, respectively. Improvements were found for waist girth, total cholesterol, aerobic fitness, and flexibility relative to controls. The change in vigorous PA, but not moderate PA, was a significant predictor of the change in eight of 11 risk factor variables measured. Conclusions. Rapid and dramatic increases in PA among previously insufficiently active adults can result in important health benefits.

Exercise training improves fasting glucose control.

Purpose Numerous studies have measured changes in fasting blood glucose (FBG) levels in response to physical activity (PA) interventions. While studies involving clinical populations such as type 2 diabetics typically report significant reductions, most others report no change in FBG. This study investigated changes in FBG in apparently healthy adults following a PA intervention. Methods We measured fingertip samples for FBG pre and post a 40-day PA program in 575 insufficiently active adults. The PA goal was at least 30 minutes of moderate exercise daily, and there was 73% compliance. Results A PA questionnaire showed the average level of activity was 69 ± 46 min/wk preintervention, and this increased to 635 ± 458 min/wk postintervention. When the change in FBG was regressed against baseline FBG levels, there was a significant negative relationship (y = 2.623 − 0.471 × x; r = 0.472; P < 0.0001). The regression line showed, on average, subjects with low pre-study glucose levels had increased FBG while those with high levels had reductions in FBG. Conclusion It appears that the body’s response to PA training is to upregulate glucose control, which is reflected in tighter FBG levels around a physiological set point (5.6 mmol/L, in the present study). Regulation of blood glucose is a complex neuroendocrine process with numerous organs involved, but it was not possible in the present study to determine which of these regulatory steps are involved in exercise-induced changes of FBG.

Agreement between pre-exercise screening questionnaires completed online versus face-to-face

Objectives To investigate the levels of agreement between self-reported responses to the Adult Pre-exercise Screening System (APSS) questionnaire using online versus face-to-face (F2F) modalities. Design Convenience sample of adults completing a pre-exercise screening questionnaire using different modalities. Methods Adult volunteers (n = 94) were recruited to complete the APSS using both online and F2F modalities. Participants were provided a URL link to an online APSS questionnaire then followed-up the next day in a F2F interview. Objective health risk factors were also measured. Comparisons between responses were undertaken using kappa and correlation statistics to determine levels of agreement. Results The levels of agreement between online versus F2F responses for the seven compulsory Stage 1 questions (known diseases and signs and/or symptoms of disease) were >94% (kappa = 0.644–0.794). Response comparisons for Stage 2 questions on health risk factors were also generally high (>82% agreement) but there were larger differences between reported and measured risk factors in Stage 3. Conclusions Levels of agreement between the Stage 1 responses were substantial and support the use of this online option for pre-exercise screening. There were larger differences between self-reported and objectively measured health risk factors in Stages 2 and 3.

Comparison of Reduced Volume-High Intensity Interval Training Compared to High Volume Training on Endurance Performance in Triathletes

PURPOSE To investigate changes in physiological and performance variables in triathletes following a 4-wk period of reduced training volume and increased training intensity. METHODS Sixteen moderately trained triathletes were randomly allocated to 2 groups: a control (CON) group, which followed their usual training, or a high-intensity interval training (HIIT) group, which completed 2 HIIT sessions per week during 4 wk of reduced training volume Results: Maximal oxygen consumption (VO2max) increased significantly in the HIIT group (P = .03, d = 0.5) but remained unchanged in the CON group. Cycling power at first and second ventilatory thresholds increased significantly in the HIIT subjects (P = .03, d = 1.0) and was unchanged in the CON participants (P = .57). During the simulated triathlon test, pretest-posttest cycling times and average power were unchanged in both groups (P > .05). No significant interactive effects between groups were observed for running time (P = .50). CONCLUSION After a 4-wk HIIT program, VO2max and power at first and second ventilatory thresholds were found to have increased significantly while cycling and running performance were unchanged, despite an overall reduction in training time. In the present study, performance was only shown to improve with usual (high-volume) training. Summarizing, in order to improve running or cycling performances, high-volume training programs are highly recommended.