High-intensity interval training for improving health-related fitness in adolescents: a systematic review and meta-analysis

BACKGROUND: High-intensity interval training (HIIT) may be a feasible and efficacious strategy for improving health-related fitness in young people. The objective of this systematic review and meta-analysis was to evaluate the utility of HIIT to improve health-related fitness in adolescents and to identify potential moderators of training effects. METHODS: Studies were considered eligible if they: (1) examined adolescents (13-18 years); (2) examined health-related fitness outcomes; (3) involved an intervention of ≥4 weeks in duration; (4) included a control or moderate intensity comparison group; and (5) prescribed high-intensity activity for the HIIT condition. Meta-analyses were conducted to determine the effect of HIIT on health-related fitness components using Comprehensive Meta-analysis software and potential moderators were explored (ie, study duration, risk of bias and type of comparison group). RESULTS: The effects of HIIT on cardiorespiratory fitness and body composition were large, and medium, respectively. Study duration was a moderator for the effect of HIIT on body fat percentage. Intervention effects for waist circumference and muscular fitness were not statistically significant. CONCLUSIONS: HIIT is a feasible and time-efficient approach for improving cardiorespiratory fitness and body composition in adolescent populations.

Population biology of swift (Apus apus) ectoparasites in relation to host reproductive success

1We censused ectoparasite populations of adult and nestling swifts over the course of the host's breeding season. Nearly all of the birds were infested with chewing lice and two-thirds of the nests were infested with louse flies. Feather mites were observed but not quantified.2Lice and louse flies both showed aggregated distributions among hosts. Louse eggs, hatched lice and adult louse flies had negative binomial distributions, whereas the aggregated distribution of louse fly pupae was not adequately described by negative binomial or Poisson models.3Transmission of lice from parents to offspring was documented. A comparison of the age structure of lice on parents and offspring indicated that most transmission was by nymphal lice.4Host reproductive success and survival appeared to be independent of the number of lice or louse flies. Neither parasite correlated with the number, body mass, or date of fledging of young birds, nor with the overwinter survival of adults. We caution, however, that experimental manipulations of parasite load are required for a definitive test of the impact of ectoparasites on evolutionary fitness components.

Oxygen uptake and heart rate during simulated wildfire suppression tasks performed by Australian rural firefighters

Objective: Australian rural fire crews safeguard the nation against the annual devastation of wildfire. We have previously reported that experienced firefighters identified seven physically demanding tasks for Australian rural fire crews suppressing wildfires. These firefighters rated the operational importance, typical duration, core fitness components, and likely frequency of the seven tasks. The intensity of these duties remains unknown. The aim of this study was to quantify the oxygen uptake (VO2), heart rate (HR) and movement speed responses during simulations of these physically demanding wildfire suppression tasks. Method: Twenty six rural firefighters (20 men, six women) performed up to seven tasks, during which time their HR and movement speed were recorded. The VO2 for each task was also calculated from the analysis of expired air collected in Douglas bags. Firefighters’ HR and movement speed were measured using HR monitors and portable global positioning system units, respectively. Results: The hose work tasks elicited a VO2 of 21-27 mL·kg-1·min-1 and peak HR of 77-87% age-predicted maximal HR (HRmax). Hand tool tasks were accompanied by VO2 of 28-34 mL·kg-1·min-1 and peak HR of 85-95%HRmax. Firefighters’ movement speed spanned 0.2 ± 0.1 to 1.8 ± 0.2 m·s-1 across the seven tasks. The cardiovascular responses in the hand tool tasks were, in most cases, higher (P<0.05) than during those elicited by the hose work tasks. Conclusions: The cardiovascular responses elicited during simulations of physically demanding wildfire suppression approximated those reported for similar tasks in urban and forestry fire fighting jurisdictions. The findings may prompt Australian rural fire agencies to consider cardiovascular disease risk screening and physical selection testing to ensure that healthy and fit firefighters are deployed to the fire ground.

Utility of the multi-component training distress scale to monitor swimmers during periods of training overload

The purpose of the present study was to determine the efficacy of the multi-component training distress scale (MTDS), in monitoring swimmers prior to national competition. Twenty-one national-level adolescent swimmers completed eight weeks of testing. Once a week participants completed an 8 × 50 m sprint test,
vertical jump test, sit-and-reach test, the MTDS and the
Recovery-Stress Questionnaire for Athletes (REST-Q). All testing
was incorporated into the swimmers’ normal training programme.
The REST-Q accounted for the following variances in performance:
flexibility (14.6%,p= 0.009), power output (17.7%,p= 0.003),swimming speed (15.5%,p
= 0.006) and swimming endurance(17.5%,p= 0.002). In comparison, the MTDS accounted for thefollowing variances in performance:
flexibility (12.1%, p= 0.095),power output (16.4%,p= 0.023), swimming speed (20.5%,p = 0.003) and swimming speed endurance (23.8%,p= 0.001).The findings of the current study suggest that both the REST-Q Sport and the MTDS have the capacity to predict performance on a range of fitness components associated with swimming.

Effects of strength, flexibility and moderate intensity cardiovascular exercise on measures of fitness in sedentary women

The maintenance of functional physical fitness across the lifespan depends upon the presence or absence of disease, injury, and the level of habitual physical activity. The prevalence of sedentariness rises with increasing age culminating in 31% of elderly women being classified as leading a sedentary lifestyle. Exercise prescription that involves easily accomplished physical activity may result in the maintenance of mobility into old age through a reduction in the risk of premature death and disablement from cardiovascular disease and a reduction in the risk of falls and injuries from falls. It may be that short bouts of physical activity are more appealing to the sedentary and to those in full time employment than longer bouts, and it may be that short bouts of exercise, performed three times per day, can improve physical fitness. The purpose of this study was therefore to examine the problem: Does exercise session duration, initial cardiovascular fitness, and age group effect changes in functional physical fitness in sedentary women training for strength, flexibility and aerobic fitness? Twenty-three, sedentary women aged between 19 and 54 years who were employed at a major metropolitan hospital undertook six weeks of moderate intensity physical activity in one of two training groups. Participants were randomly allocated to either short duration (3 x 10 minute), or long duration (30 minute), exercise groups. The 3 x 10 minute group (n=13), participated in three, 10 minute sessions per day separated by at least 2 hours, 3 days per week. The 30 minute group (n=10), participated in three 30 minute sessions per week. The total amount of work was similar, with an average of 129 and 148 kcal training day for the 3 x 10 minute and 30 minute groups, respectively. The training program incorporated three walking and stair climbing courses for aerobic conditioning, a series of eleven static stretches for joint flexibility, and isotonic and isometric strength exercises for lower and upper body muscular strength. Measures of functional strength, functional flexibility and cardiovascular fitness were assessed prior to training, and immediately following the six week exercise program. A two way analysis of variance (Group x Time) was used to examine the effect of training and group on the dependent variables. The level of significance, 0.05 was adopted for all statistical tests. Mean hand grip strength showed for both groups no significant change over time for the 3 x 10 minute group (30.7kg to 31.7kg) and 30 minute group (30.2kg to 32.4kg). Leg strength showed a trend for improvement (p=0.098) in both the 3 x 10 minute and 30 minute training groups representing a 15% and 18% improvement, respectively. Combined right and left neck rotation significantly improved in the 3 x 10 minute group (82.8° to 92.0°) and 30 minute group (82.5° to 91.5°). Wrist flexion and extension improved significantly in 3 out of the 4 measurements. Left wrist flexion improved significantly by an average of 7.0% for the 3 x 10 minute and 4.9% for the 30 minute group. Right and left wrist extension improved significantly in the 3 x 10 minute and 30 minute training groups (5.9% and 6.8%, respectively). Hip and spine flexibility improved 3.4cm (35.2cm to 38.6cm) in the 3 x 10 minute group, and 6.6cm (37.4cm to 44.0cm) in the 30 minute group. There was a significant improvement in cardiovascular fitness for both groups representing a 22% improvement in the 3 x 10 minute group (27.2 to 33.2 ml kg min), and a 25% improvement in the 30 minute group (27.5 to 34.4 ml -kg min). No significant difference was shown in the degree of improvement in cardiovascular fitness over six weeks of training for subjects of either low or moderate initial aerobic fitness. Grip strength showed no significant changes over time for either the young-aged (19-35 years) or middle-aged (36-54 years) groups. Leg strength showed a trend for improvement (p=0.093) in the young-aged group (63.5kg to 71.9kg) and middle-aged group (69.3kg to 85.8kg). Neck rotation flexibility improved a similar amount in both the young and middle aged groups representing an improvement of 9.9° and 8.0° respectively. There was significant improvement in two of the four measures of wrist flexibility. Hip and spine flexibility was significantly greater in the young-aged group compared to the middle-aged group (38.5cm and 30.7cm, respectively). There was a significant improvement in hip and spine flexibility over the six week training program representing an increase in reach of 6.5cm for the young age group and 4.9cm for the older group. The middle-aged subjects had significantly lower cardiovascular fitness than their younger peers, scoring 22.8 and 30.7 ml -kg min, respectively. Cardiovascular fitness improved a similar amount in both age groups representing a significant improvement of 23.8% and 28.1% for the younger-aged and middle-aged subjects, respectively. The findings of this study suggest that short bouts of exercise may be equally as effective as longer bouts of exercise for improving the flexibility and cardiovascular components of functional physical fitness in sedentary young and middle aged women. Additionally short bouts of exercise may be more attractive than longer bouts of exercise for the beginning exerciser as they may more easily fit into the busy lifestyle encountered by many people in today's society. Sedentary young and middle-aged women should benefit from static flexibility exercises designed to improve and/or maintain functional flexibility and thus maintain mobility and reduce the incidence of muscular injury. Regular, brisk walking, incorporating some stair climbing, is likely to be beneficial in improving cardiovascular health and perhaps also in improving leg strength, thereby helping to improve and maintain functional physical fitness for both young and middle-aged sedentary women.

Gender, age, and educational-attainment differences in Australian adults' participation in vigorous sporting and fitness activities

Background: Participation in regular vigorous physical activity could confer health benefits additional to those derived from moderate-intensity physical activities that are currently the focus of public health strategies.
Methods: Sociodemographic differences in reported participation in vigorous sporting and fitness activities over the past 2 weeks were examined using cross-sectional data from an Australian urban population sample.
Results: Participation at least once in any form of vigorous physical activity and regular participation (six or more sessions) both decreased across successive age groups and from high to low levels of education. The most frequently reported types of vigorous physical activity were cycling (13.3%), jogging (10.1%), swimming (8.4%) for men; and, swimming (8.9%), cycling (8.8%) and aerobics (8.6%) for women.
Conclusion: Rates of regular participation in vigorous activities were low. Interventions might focus on ways to encourage younger adults to engage more regularly in these activities and to maintain participation through the lifespan.

Training packages and the AQTF: freedom to move or components of a compliance-driven straightjacket?

This paper reports on a PhD research project being undertaken through the Faculty of Education, Deakin University. Training Packages and the Australian Quality Training Framework (AQTF) form part of the ruling relations of VET, but how do they operate in practice? Do they provide frameworks within which training professionals are free to use judgement and respond in innovative ways to local learning and assessment contexts? Do they impose rigid 'guidelines' within which the decision-making authority of practitioners over appropriate practices is displaced by that of auditors, constraining creativity and creating pressures towards conformity? Or does their impact vary, depending on how they are interpreted and who is doing the interpreting? My PhD research explores issues relating to the use of Training Packages in workbased learning. Interview data suggests that, in practice, different training organisations respond very differently to a regulatory framework that aims to achieve national consistency. Some practitioners describe working in a compliance-driven environment, in which their ability to meet the needs of learners is stifled by standardised training and assessment practices imposed by Training Packages and the AQTF. This view is reflected in phrases such as 'you're not allowed to…', and 'you always feel uneasy because you've got AQTF compliance, inspections, auditors'. In contrast, other practitioners talk about having freedom to design learning and assessment programs for their particular target group and context, providing they stay within broad guidelines that guarantee national recognition of qualifications they issue. This view is reflected in comments such as 'it just leaves it open … to be as creative and flexible as you like', and 'It just gives us freedom'. This paper explores the proposition that the impact of these abstract and generalised texts is influenced by local interpretations, and it considers the role that organisational culture plays in determining these interpretations.

An exploration of the components of relational bonds to an arts festival brand

This research investigates the nature of the bonds that consumers form with a brand that provides highly uncertain outcomes, and is only available intermittently. The research model draws upon elements of Keller’s (2001) conceptualisation of brand resonance, and extends McAlexander, Kim, and Roberts’ (2003), and Muniz and O’Guinn’s (2001) brand community construct, testing these in an atypical service environment. Qualitative research suggested the need for a broader view of the bond formed in these circumstances, specifically one comprising measures of anticipation of usage, social attraction, commitment, loyalty, and trust. This paper reports on analysis undertaken to develop such a construct, which has been labelled “brand affinity”. Tests for discriminant validity suggest that the brand affinity construct is a distinct construct that can be used to measure consumer attitudes toward a highly uncertain, intermittently available product.

Photosynthesis of hydrogen and methane as key components for clean energy system

While researchers are trying to solve the world's energy woes, hydrogen is becoming the key component in sustainable energy systems. Hydrogen could be produced through photocatalytic water-splitting technology. It has also been found that hydrogen and methane could be produced through photocatalytic reduction of carbon dioxide with water. In this exploratory study, instead of coating catalysts on a substrate, pellet form of catalyst, which has better adsorption capacity, was used in the photo-reduction of carbon dioxide with water. In the experiment, some water was first absorbed into titanium dioxide pellets. Highly purified carbon dioxide gas was then discharged into a reactor containing these wet pellets, which were then illuminated continuously using UVC lamps. Gaseous samples accumulated in the reactor were extracted at different intervals to analyze the product yields. The results confirmed that methane and hydrogen were photosynthesized using pellet form of TiO₂ catalysts. Hydrogen was formed at a rate as high as 0.16 micromoles per hour (μmol h⁻¹). The maximum formation rate of CH₄ was achieved at 0.25 μmol h⁻¹ after 24 h of irradiation. CO was also detected.

Finite element simulation of deformation processes of micro-components

The aim of this paper is to improve the understanding of deformation of micro medical needle and thread during assembly and then to develop an economical and flexible deformation method. Therefore, the swaging process is computationally simulated with the finite element method in this paper. A commercially available explicit nonlinear finite element analysis code, LS-Dyna, is used to model the 3-D deformation and contact problem. As the firmness of the assembly on the needle depends on the contact force and friction, the contact and the slide between the needle and thread are taken into account in the simulation. The general surface-to-surface contact algorithm (STS) is used to simulate the contact. The paper provides an insight into the deformation of the micro products.

A longitudinal study of body change strategies of fitness center attendees

This study evaluated predictors of strategies to change weight and muscles among men and women who attend fitness centers. A questionnaire was completed by 107 men (mean age = 39.17, SD = 13.14), and 151 women (mean age = 35.31, SD = 11.38) who regularly attended fitness centers at two points in time, one year apart. The only unique predictor of body change strategies over time for men was body dissatisfaction predicting drive for thinness; for women, body dissatisfaction predicted strategies to lose weight, drive for thinness, use of food supplements to lose weight and levels of bulimia. Media messages also predicted drive for thinness and bulimia among women. These findings would suggest that attendance body dissatisfaction is an important factor predicting other normative and health risk behaviors among fitness center attendees, particularly women at a fitness center over a 12 month period was not generally associated with adverse health risk behaviors.

Sustainable components of leadership effectiveness in organizational performance

Purpose – The objective is to describe a selection of sustainability components of leadership effectiveness in organizational performance.
Design/methodology/approach – The paper is based on a conceptual discussion. Findings – The paper contributes to descriptive models that address sustainability components of leadership effectiveness in organizational performance. The study highlights some common views that exist in the management literature and in prosperous management practice related to the direct impact of the relationship in organizational performance between leadership and effectiveness. In fact, it also highlights the critical or sceptical views of leadership effectiveness in organizational performance raised in the literature. Research limitations/implications – The paper contends that the actual leadership effectiveness in organizational performance varies over time and across contexts. At times, the achievement in organizational performance is the outcome of prosperous and conscious leadership, while it at other times may be the outcome of poor and deficient leadership. The topic at hand is positioned and limited to the interface that may describe and explain the connection between these two views. Furthermore, it is limited to corporate decision making and business behaviour in relation to leadership effectiveness and organizational performance. Practical implications – The leadership of an organization need not only to be successful today, but they also need to be successful tomorrow to stay in control and to flourish. Quality control and quality assurance are no longer enough for most organizations. They need to build an awareness of the sustainability components into processes of their management and business practices (i.e. internal and external ones) in order to be judged as successful in corporate decision-making and business behaviour in organizational performance in the long term. Originality/value – The principal contributions of the study are a model of timely leadership effectiveness, a model of contextual leadership effectiveness, and a typology of leadership effectiveness in corporate decision-making and business behaviour. These contributions provide theoretical and managerial ideas and insights into the sustainability components of leadership effectiveness in organizational performance.