Self-reported and accelerometry measures of sleep components in adolescents living in Pacific Island countries and territories: Exploring the role of sociocultural background

OBJECTIVES

The objective of this study is to assess the concordance and its association with sociocultural background of a four-question survey with accelerometry in a multiethnic adolescent population, regarding sleep components. Based on questions from the Pittsburgh Sleep Quality Index and adapted to a school context, the questionnaire focussed on estimating sleep onset time, wake-up time and sleep duration on both weekdays and weekends. This subjective survey was compared with accelerometry data while also considering the influence of sociocultural factors (sex, place of living, ethnic community and socio-economic status).

METHODS

Adolescents aged 10.5-16 years (n = 182) in New Caledonia completed the survey and wore an accelerometer for seven consecutive days. Accelerometry was used to determine sleep onset and wake-up time using validated algorithms. Based on response comparison, Bland-Altman plots provided agreement between subjective answers and objective measures. We categorized participants' answers to the survey into underestimated, aligned and overestimated categories based on time discrepancies with accelerometry data. Multinomial regressions highlighted the sociocultural factors associated with discrepancies.

RESULTS

Concordance between the accelerometer and self-reported assessments was low particularly during weekends (18%, 26% and 19% aligned for onset sleep time, wake-up time and sleep duration respectively) compared with weekdays (36%, 53% and 31% aligned, respectively). This means that the overall concordance was less than 30%. When considering the sociocultural factors, only place of living was associated with discrepancies in onset sleep time and wake-up time primarily on weekdays. Rural adolescents were more likely to overestimate both onset sleep time (B = -1.97, p < 0.001) and wake-up time (B = -1.69, p = 0.003).

CONCLUSIONS

The study found low concordance between self-assessment and accelerometry outputs for sleep components. This was particularly low for weekend days and for participants living in rural areas. While the adapted four-item questionnaire was useful and easy to complete, caution should be taken when making conclusions about sleep habits based solely on this measurement.

Training strategies of 10,074 athletes from 121 countries based on human development index in early COVID-19 lockdown

The aim of this study was to investigate relationships between changes in training practices and human development index (HDI) levels, and identify strategies employed by athletes who consistently maintained their training quantity during the first 100 days of the COVID-19 pandemic. A total of 10,074 athletes (5290 amateur and 4787 professional athletes from 121 countries) completed an online survey between 17 May to 5 July 2020. We explored their training practices, including specific questions on training frequency, duration and quantity before and during lockdown (March-June 2020), stratified according to the human development index (HDI): low-medium, high, or very high HDI. During the COVID-19 lockdown, athletes in low-medium HDI countries focused on innovative training. Nevertheless, women and amateur athletes experienced a substantial reduction in training activity. Performance-driven athletes and athletes from higher HDI indexed countries, were likely to have more opportunities to diversify training activities during lockdowns, facilitated by the flexibility to perform training away from home. Factors such as lockdown rules, socioeconomic environment, and training education limited training diversification and approaches, particularly in low-medium and high HDI countries. Athletes (amateurs and professionals) who maintained the quantity of training during lockdown appeared to prioritize basic cardiovascular and strength training, irrespective of HDI level. Modifying training and fitness programs may help mitigate the decrease in training activities during lockdowns. Customized training prescriptions based on gender, performance, and HDI level will assist individuals to effectively perform and maintain training activities during lockdowns, or other challenging (lockdown-like) situations.

Prevalence, causes and contexts of childhood overweight and obesity in the Pacific region: a scoping review

Background

Non-communicable diseases (NCDs) are a major threat to health and development and account for 75% of deaths in the Pacific Islands Countries and Territories (PICTs). Childhood obesity has been identified as a main risk factor for NCDs later in life. This review compiled overweight and obesity (OWOB) prevalence (anthropometric data) for children aged six to 12 years old living in the Pacific region and identified possible related causes.

Methods

We conducted a systematic search using PubMed, Google Scholar and ScienceDirect for articles published between January 1980 and August 2022. We also searched for technical reports from Ministries of Health. Guided by the eligibility criteria, two authors independently read the selected articles and reports to extract and summarise relevant information related to overweight and obesity.

Results

We selected 25 articles, two worldwide analyses of population-based studies and four national reports. Information revealed that childhood OWOB prevalence reached 55% in some PICTs. This review also indicated that age, gender and ethnicity were linked to children's weight status, while dietary practices, sleep time and level of physical activity played a role in OWOB development, as well as the living environment (socio-economic status and food availability), parenting practices and education level.

Conclusion

This review highlighted that anthropometric data are limited and that comparisons are difficult due to the paucity of surveys and non-standardized methodology. Main causes of overweight and obesity are attributed to individual characteristics of children and behavioural patterns, children's socio-economic environment, parenting practices and educational level. Reinforcement of surveillance with standardised tools and metrics adapted to the Pacific region is crucial and further research is warranted to better understand root causes of childhood OWOB in the Pacific islands. More robust and standardized anthropometric data would enable improvements in national strategies, multisectoral responses and innovative interventions to prevent and control NCDs.

An examination of procrastination in a multi-ethnic population of adolescents from New Caledonia

BACKGROUND

Although procrastination has been widely studied in adults, comparatively little work has focused on adolescent procrastination, especially in the Pacific region. As a contribution to knowledge and diversification of population sampling, therefore, we examined procrastination in a multi-ethnic sample of adolescents from New Caledonia. Specifically, we examined gender and ethnic differences in procrastination, as well as sociodemographic and ethnic identity predictors of procrastination.

METHODS

927 adolescents (474 boys, 453 girls; age M = 13.2 years) completed measures of procrastination and ethnic identity, and reported their ethnicity (Kanak vs. Polynesian vs. European). Sociodemographic data (sex, age, area of residence and socioeconomic status) were also collected.

RESULTS

An analysis of variance indicated significant ethnic (Kanak and Polynesian adolescents had higher procrastination than European adolescents) and sex differences (girls had higher procrastination than boys), but no significant interaction. Regression analysis showed that higher procrastination was significantly associated with sex, ethnicity, age, and the interaction between ethnicity and ethnic identity. Moderation analysis showed that ethnic identity moderated the relationship between ethnicity and procrastination, but only in Kanak adolescents.

CONCLUSION

Relatively high levels of procrastination were observed in Kanak and Polynesian adolescents, and in girls. These findings, while preliminary, may have important implications for academic attainment in the New Caledonian context.

Adolescent screen time and unhealthy food consumption in the context of the digital development in New Caledonia

OBJECTIVE

For several years, the Pacific Island Countries and Territories (PICTs) have been undergoing digital developments that have had an impact on the time adolescents spend in front of screens. The association between screen time and the overconsumption of unhealthy foods has been observed but little studied in New Caledonia. The twofold aim of this research was to analyze adolescent screen time based on the number of screens at home, gender, place of living, ethnic community and family socio-professional category and determine the link with the consumption of unhealthy food and drinks.

METHODS

Self-report questionnaires on time spent in front of tablets, computers and mobile phones, as well as the consumption of unhealthy food and drinks, were administered between July 2018 and April 2019 to 867 adolescents from 11 to 15 years old during school hours in eight schools across the three provinces of New Caledonia.

RESULTS

Adolescents in rural areas had fewer screens than their urban counterparts, and the number of screens determined the amount of screen time, which was significantly higher among the adolescents living in urban areas (3.05 h/day weekdays vs rural 2.33 h/day). Screen time was not related to gender, socio-professional category or ethnic community, but correlations were found between screen time and consumption of unhealthy food and drinks. Those who consumed less than 1 u/day of unhealthy drinks watched screens for 3.30 h/day, whereas those who consumed more than 1 u/day watched screens for 4.13 h/day. Also, those who consumed less than 1 u/day of unhealthy food watched screens for 2.82 h/day and those consuming more than 1 u/day did so for 3.62 h/day. Melanesians and Polynesians consumed greater quantities of unhealthy food and drinks than Europeans. As the consumption of unhealthy products is linked to screen time in the context of digital development, there is an urgent need to address the excessive consumption of unhealthy foods in Oceanian populations, particularly among young people.

Generational issues in linking family farming production, traditional food in diet, physical activity and obesity in Pacific Islands countries and territories: the case of the Melanesian population on Lifou Island

In the Melanesian culture, traditional activities are organized around family farming, although the lifestyle transition taking place over the last several decades has led to imbalances in diet and physical activity, with both leading to obesity. The aim of this interdisciplinary study was to understand the links between family farming (produced, exchanged, sold, and consumed food), diet (focused on produced, hunted, and caught food), physical activity (sedentary, light, and moderate-to-vigorous physical activity) and obesity in Melanesian Lifou Island families (parents and children). Forty families, including 142 adults and children, completed individual food frequency questionnaires, wore tri-axial accelerometers for seven continuous days, and had weight and height measured with a bio-impedance device. A family farming questionnaire was conducted at the household level concerning family farming practices and sociodemographic variables. Multinomial regression analyses and logistic regression models were used to analyze the data. Results showed that family farming production brings a modest contribution to diet and active lifestyles for the family farmers of Lifou Island. The drivers for obesity in these tribal communities were linked to diet in the adults, whereas parental socioeconomic status and moderate-to-vigorous physical activity were the main factors associated to being overweight and obesity in children. These differences in lifestyle behaviors within families suggest a transition in cultural practices at the intergenerational level. Future directions should consider seasonality and a more in-depth analysis of diet including macro- and micro- nutrients to acquire more accurate information on the intergenerational transition in cultural practices and its consequences on health outcomes in the Pacific region.

The Barriers to and Facilitators of Physical Activity and Sport for Oceania with Non-European, Non-Asian (ONENA) Ancestry Children and Adolescents: A Mixed Studies Systematic Review

BACKGROUND

Participation in sport and physical activity (PA) leads to better overall health, increased life expectancy, and decreased mortality rates across the lifespan; however, there may be a range of individual, family, and community factors that influence PA participation among ONENA children and adolescents residing in the 22 Pacific Island Countries and Territories (PICT) and Australia. This review aimed to synthesise existing quantitative and qualitative literature regarding barriers to and facilitators of PA and sport among ONENA youth.

METHODS

The literature was systematically searched to include studies reporting barriers to and facilitators of PA and sports participation among ONENA children and adolescents aged 0-18 years residing in the 22 PICT and Australia. Using a pre-established taxonomy based on the social-ecological model, a deductive analysis was performed. Quality appraisal was performed using the mixed methods appraisal tool.

RESULTS

Of 1388 articles, 14 studies were included, with 128 ONENA children and adolescent participants across the four qualitative studies; 156,581 ONENA children and adolescents across the seven quantitative studies; 801 parents, children, and adolescents in one quantitative study; and 642 parents in two quantitative studies. Of the 14 included studies, none were based in Australia and only 10 of the 22 PICT were reported as the participants' residence: Palau, New Zealand, Tonga, Cook Islands, Kiribati, Samoa, Solomon Islands, Tuvalu, Vanuatu, and Fiji. Four studies reported barriers, and another four studies reported facilitators of PA and sport, with the remaining studies reporting both barriers and facilitators. Overall, there were more barriers reported (30 in total) than facilitators (27 in total).

CONCLUSIONS

Research in this area is lacking, with ONENA youth living in Australia and 12 PICT not represented. Overall, there were a larger number of facilitators experienced at individual and interpersonal levels, while barriers were highest at the community level, with the policy level having facilitators and barriers equally represented. Programs that offer PA and sport participation options with embedded SDT-informed strategies for all family members; that are accessible through existing transport and related social, cultural, and physical infrastructure; and that are committed to communities through formal co-design partnerships are needed, to enhance the PA and sport participation of ONENA youth residing in PICT.

Associations between weight status, body satisfaction, ethnic identity and self-esteem in Oceanian adolescents

BACKGROUND

Self-esteem has consistently been observed to be relatively low in adolescents with obesity. In the Pacific region, the prevalence of obesity in adolescence is high, but few studies have considered issues of self-esteem in this population.

OBJECTIVE

To examine associations between weight status, body dissatisfaction and self-esteem in a sample of New Caledonian adolescents and to test for moderation effects of ethnicity on predictors of self-esteem.

METHODS

Objective anthropometric measures (height, weight, waist circumference and thickness of skinfolds) were obtained in a multi-ethnic sample of New Caledonian adolescents. Body mass index (BMI), waist-to-height ratio and the sum of four skinfolds thickness were used as proxies of weight status. Indices of ethnic identity, self-esteem, socio-demographic data (socioeconomic status, ethnicity, gender, urbanicity of residence) and body dissatisfaction were obtained using survey methods.

RESULTS

Between-group analyses indicated that adolescents of European/white origin had significantly higher self-esteem than adolescents with Oceanian Non-European Non-Asian ancestry (ONENA). However, low self-esteem was significantly associated with weight status and body dissatisfactions in European/white adolescents but not ONENA adolescents. Ethnicity moderated the relationships of predictors (BMI z-score, body dissatisfaction, age, urbanicity and ethnic identity) on self-esteem, and the strongest predictors of self-esteem were ethnicity and ethnic identity.

CONCLUSIONS

While self-esteem has important consequences for adolescent well-being and health outcomes, these results highlight the importance of applying different steps to develop and maintain healthy self-esteem in the Pacific region.

Physical Activity in Adolescents Living in Rural and Urban New Caledonia: The Role of Socioenvironmental Factors and the Association With Weight Status

Physical activity (PA) is an important factor for the prevention of overweight and obesity, particularly during adolescence. This study focuses on the understudied adolescent population of New Caledonia with the aim to (1) determine the daily PA levels and estimate the sedentary time through out-of-school sitting time; (2) highlight the influence of sociodemographic and environmental factors, and (3) assess the associations of PA and sitting time with overweight and obesity. A sample of 508 school-going adolescents living in New Caledonia was surveyed about their PA habits using the International Physical Activity Questionnaire-Short Form, as well as about the context in which they usually engage in PA. The influences of the place of living and ethnic community were also investigated. Results indicated that about 66% of the adolescents performed an average of at least 60 min of PA daily. Both Melanesian adolescent boys and girls were more active than Caucasian adolescents but only when they lived in rural areas (females: 115 vs. 93 min/day, p = 0.018; males: 133 vs. 97 min/day, p = 0.018). Indeed, PA was reduced in an urban environment (females: 88 min/day; males: 95 min/day, p = 0.028; rural vs. urban in Melanesian adolescents). Melanesian adolescents also spent less time in out-of-school sitting than Caucasian adolescents independently of where they lived (females: 164 vs. 295 min/day, p < 0.001; males: 167 vs. 239 min/day, p = 0.001). Feeling safe was positively associated with PA levels (females: OR_adj = 2.85, p < 0.001; males: OR_adj = 4.45, p < 0.001). In the adolescent boys, accessibility to a suitable place was also an important factor (OR_adj = 2.94, p = 0.002). Finally, while PA and sitting time were negatively associated with overweight in male adolescents (OR_adj = 0.28, p = 0.044 and OR_adj = 0.39, p = 0.004), they were not in females. Living in a rural area allowed the Melanesian adolescents to maintain a more active lifestyle with more physical activities and less sitting time. Our results also indicated that safety was an important driver for engagement in PA. The urban environment in New Caledonia appears to be a contributor of a less active lifestyle in adolescents.

The Design and Development of a Food Composition Database for an Electronic Tool to Assess Food Intake in New Caledonian Families

The food environment in New Caledonia is undergoing a transition, with movement away from traditional diets towards processed and discretionary foods and beverages. This study aimed to develop an up-to-date food composition database that could be used to analyze food and nutritional intake data of New Caledonian children and adults. Development of this database occurred in three phases: Phase 1, updating and expanding the number of food items to represent current food supply; Phase 2, refining the database items and naming and assigning portion size images for food items; Phase 3, ensuring comprehensive nutrient values for all foods, including saturated fat and total sugar. The final New Caledonian database comprised a total of 972 food items, with 40 associated food categories and 25 nutrient values and 615 items with portion size images. To improve the searchability of the database, the names of 593 food items were shortened and synonyms or alternate spelling were included for 462 foods. Once integrated into a mobile app-based multiple-pass 24-h recall tool, named iRecall.24, this country-specific food composition database would support the assessment of food and nutritional intakes of families in New Caledonia, in a cross-sectional and longitudinal manner, and with translational opportunities for use across the wider Pacific region.

'Eating well' in Pacific Islands countries and territories: A qualitative and normative approach to food cultures in New Caledonia

In recent decades, the food cultures of the Pacific populations have undergone a profound transition, particularly because the increasing trade exchanges with Western countries have facilitated access to a wide range of processed foods. Essentially, a new normative model of eating is now taking the place of the traditional models. The aims of this qualitative study were to explore what 'eating well', 'good food' and 'bad food' now mean in the New Caledonian family context and, more broadly, to categorise the current food practices and representations in adolescents' families. A double qualitative methodology was applied: 59 face-to-face interviews with 30 parents and 29 adolescents in both rural and urban areas and 15 collective structured discussions with middle-school classes (11- to 16-year-olds) of almost 25 students each. The main results showed various normative frames for nutrition, food quantities, local provenance, and personal taste. Food practices were related to food availability (having a home garden or involvement in family farming), socioeconomic status and community. In addition, access to nutritional information, temporal and financial constraints mostly in the urban area, and the role of food socialisation between parents and children had an impact on food practices and perceptions. The permanence of food cultures, mainly observed in families in rural areas, and the social inequalities in urban areas regarding food availability are highlighted. The positive perception of 'local food' as 'cultural', 'organic' and 'healthy' may help policymakers communicate clear messages to reach a sustainable food system.

The effect of an Olympic distance triathlon on the respiratory muscle strength and endurance in triathletes

High-intensity exercise, marathons, and long distances triathlons have been shown to induce the fatigue of respiratory muscles (RMs). Never-theless, fatigue and the recovery period have not been studied in re-sponse of an Olympic distance triathlon (1.5-km swim, 40-km bike, 10-km run: short-distance triathlon). The aim of this study was to evaluate the RM fatigue induced by an Olympic distance triathlon. Nine male triath-letes (24±1.1 years) underwent spirometric testing and the assessment of RM performance. Respiratory function tests were conducted in sit-ting position. Spirometric parameters, maximal inspiratory and expirato-ry pressures, and RM endurance assessed by measuring the time limit were evaluated before (pre-T), after (post-T), and the day following the triathlon (post-T-24 hr). Residual volume increased: pre-T vs. post-T (P<0.002), maximal inspiratory pressure significantly decreased from 127.4±17.2 (pre-T) to 121.6±18.5 cmH₂O (post-T) (P<0.001) and returned to the pre-T value 24 hr after the race (125.0±18.6). RM endurance sig-nificantly decreased from 4:51±0:8 (pre-T) to 3:13±0:7 min (post-T, P< 0.001) and then remained decreased for 24 hr after the race from 4:51± 0:8 (pre-T) to 3:39±0:4 min 24 hr after (P<0.002). Both, strength and en-durance of inspiratory muscles decrease after Olympic distance triath-lon. Furthermore, the impaired of inspiratory muscle endurance 24 hr after the race suggested a slow recovery and persistence of inspiratory muscle fatigue.

Overweight in the pluri-ethnic adolescent population of New Caledonia: Dietary patterns, sleep duration and screen time

BACKGROUND

A high prevalence of overweight and obesity has been found in adolescents of New Caledonia and other Pacific Island Countries and Territories. Although Westernization may contribute to the weight gain in populations of Oceanian, Non-European, Non-Asian ancestry (ONENA), little is known about the sociodemographic and lifestyle factors associated with overweight in the Melanesian and Polynesian adolescents of New Caledonia.

METHODS

In this cross-sectional study, a pluri-ethnic sample of New Caledonian adolescents (N = 954; age M = 13.2 years) completed a survey to estimate sleep duration, screen time, and dietary pattern using a food frequency questionnaire. Demographic data (gender, ethnicity, socioeconomic status: SES, area of residence) were collected, and anthropometric measures were used to compute weight status.

FINDINGS

We found a higher risk for being overweight in Melanesian (OR = 1.67) and Polynesian (OR = 5.40) adolescents compared with European adolescents, even after controlling for age, SES, area of residence, dietary pattern, sleep duration and screen time. We also found that low SES (OR = 3.43) and sleep duration (OR = 0.65 per hour) were independently associated with overweight status in the European but not in ONENA adolescents.

INTERPRETATION

In this study, the main contribution to being overweight was ethnic background, i.e. being Melanesian or Polynesian. The hypothesis of a genetic influence thus seems attractive and merits further analyses.

FUNDING

This project was funded by the University of New Caledonia and the Fondation Nestlé France.

Living in Rural and Urban Areas of New Caledonia: Impact on Food Consumption, Sleep Duration and Anthropometric Parameters Among Melanesian Adolescents

BACKGROUND

Food consumption, sleep duration and overweight were assessed in rural and urban Melanesian adolescents.

METHODS

A cross-sectional survey of 312 rural and 104 urban adolescents (11-16 years old) was conducted. Food intakes were assessed by a 26-item food frequency questionnaire and then categorised into the number of serves from each of the three recommended Pacific food groups (energy foods, protective foods, bodybuilding foods), with two additional categories for foods and drinks to be avoided i.e., processed foods and sugary drinks. Number of food serves were compared with the guidelines of 50% serves from energy foods, 35% serves from protective foods and 15% serves from bodybuilding foods. Sleep duration as hours per day was self-reported and body mass index (BMI) was calculated from measured weight and height.

RESULTS

Approximately 17.9% of rural and 26.9% of urban adolescents met the guidelines for energy foods; 61.5% rural and 69.2% urban met the serves for protective foods and 88.5% and 94.2% met the serves for bodybuilding foods. Less than 6.4% rural and 1.9% urban adolescents avoided processed foods but 61.5% rural and 56.7% urban avoided sugary beverages. Sleep duration for school days was below the international recommendations and did not significantly differ between rural and urban groups: respectively, 8.16 ± 1.10 and 8.31 ± 1.29 h. Overweight/obesity percentage was 38.1% for rural and 31.7% for urban adolescents.

CONCLUSIONS

Although traditional foods, including protective food, are still part of the adolescents' diet, low consumption of the energy food group and high consumption of processed food occurs regardless of location. As poor eating habits and insufficient sleep may contribute to overweight/obesity, educational nutrition programs should target these lifestyle variables.

Impact of a neuroscience intervention (NeuroStratE) on the school performance of high school students: Academic achievement, self-knowledge and autonomy through a metacognitive approach

BACKGROUND

Contributions from the cognitive neurosciences encourage the development of innovative tools in learning. Through an innovative intervention program called NeuroStratE, we conducted a study to analyze the impact of brain knowledge, with metacognitive approach, on the academic performance of students. This analysis concerns a cohort of 311 students aged 16. Students' school results were collected over one year and compared with those of a control group. These results are qualitatively refined with student feedback on the value of the intervention program, along with individual teacher interviews. This study showed no significant difference in school results between the two groups of students. However, the study shows the relevance of the program and students acquired knowledge about the brain's functioning. Moreover, this intervention highlights the evidence of the emergence in students of greater autonomy and better self-knowledge, both contributing to a feeling of self-efficacy, which is at the core of educational success.

Body image, body dissatisfaction and weight status of Pacific adolescents from different ethnic communities: a cross-sectional study in New Caledonia

Objective(s): The prevalence of adolescent obesity is high among the various ethnic groups native to the Pacific region (European, Melanesian and Polynesian). An important factor of weight gain or loss is body size satisfaction; however, little is known about adolescent body self-perception in the Pacific region.Design: Body dissatisfaction was evaluated using the Stunkard Figure Rating Scale in a sample of 699 adolescents from rural and urban areas of New Caledonia. The socio-demographic factors associated with higher body dissatisfaction were determined by multiple linear regression modeling.Results: Our results showed a high rate of body dissatisfaction (over 70%) in the adolescents. Body dissatisfaction was strongly related to the body mass index z-score. Melanesians boys had higher body dissatisfaction scores when they felt 'too thin' while Melanesian girls showed lower body dissatisfaction when they felt 'too fat.'.Conclusion: These results showed that social pressure for thinness or musculature may be different among adolescents living in New Caledonia. These results should be taken into account in education overweight prevention programs.

Improving Pacific Adolescents' Physical Activity Toward International Recommendations: Exploratory Study of a Digital Education App Coupled With Activity Trackers

BACKGROUND

The prevalence of overweight and obesity in children and adolescents has dramatically increased in the Pacific Island countries and territories over the last decade. Childhood overweight and obesity not only have short-term consequences but are also likely to lead to noncommunicable diseases in adulthood. A major factor contributing to the rising prevalence is an insufficient amount of daily moderate-to-vigorous physical activity (MVPA). In the Pacific region, less than 50% of children and adolescents meet the international recommendations of 11,000 steps and 60 min of MVPA per day. Although studies have shown the potential of digital technologies to change behaviors, none has been proposed to guide adolescents toward achieving these recommendations.

OBJECTIVE

The aims of this study were (1) to investigate whether a technology-based educational program that combines education, objective measures of physical activity (PA), and self-assessment of goal achievement would be well received by Pacific adolescents and help change their PA behaviors toward the international PA recommendations and (2) to create more insightful data analysis methods to better understand PA behavior change.

METHODS

A total of 24 adolescents, aged 12 to 14 years, participated in a 4-week program comprising 8 1-hour modules designed to develop health literacy and physical skills. This self-paced user-centered program was delivered via an app and provided health-related learning content as well as goal setting and self-assessment tasks. PA performed during the 4-week program was captured by an activity tracker to support learning and help the adolescents self-assess their achievements against personal goals. The data were analyzed using a consistency rate and daily behavior clustering to reveal any PA changes, particularly regarding adherence to international recommendations.

RESULTS

The consistency rate of daily steps revealed that the adolescents reached 11,000 steps per day 48% (approximately 3.4 days per week) of the time in the first week of the program, and this peaked at 59% (approximately 4.1 days per week) toward the end of the program. PA data showed an overall increase during the program, particularly in the less active adolescents, who increased their daily steps by 15% and ultimately reached 11,000 steps more frequently. The consistency of daily behavior clustering showed a 27% increase in adherence to international recommendations in the least active adolescents.

CONCLUSIONS

Technology-supported educational programs that include self-monitored PA via activity trackers can be successfully delivered to adolescents in schools in remote Pacific areas. New data mining techniques enable innovative analyses of PA engagement based on the international recommendations.

Too big or too thin? New Caledonian adolescents' perceptions of overweight and underweight

OBJECTIVES

The first aim was to examine New Caledonian adolescents' views of what constitutes an overweight or underweight person. The second aim was to assess whether an environment with a high prevalence of overweight is associated with different norms of overweight or underweight in this population.

METHODS

The Stunkard Figure Rating Scale was used for a sample of 699 pluriethnic adolescents in New Caledonia. Body mass index (BMI) was assessed for each participant and weight status was determined. The factors associated with higher figure ratings were determined by linear regression modeling.

RESULTS

Multilinear regression analysis indicated that gender (being male) and BMI were associated with higher rating scores to designate overweight. Moreover, higher BMI z-scores were associated with higher underweight figure ratings. Ethnicity, area of residence, age, and socioeconomic status were not associated with higher ratings of body image.

CONCLUSIONS

These findings show that an environment with a high prevalence of overweight does not necessarily shift adolescent "norms," contrary to visual normalization theory. These results should be taken into account in educational overweight prevention programs.

Energy drink consumption in a pluri-ethnic population of adolescents in the Pacific

OBJECTIVE

Energy drinks are very popular among teenagers but may cause health problems. Energy drink consumption is partly associated with energy drink perception, but little is known about this in the Pacific Island Countries and Territories. The aim of this cross-sectional study was to identify the relationships between energy drink consumption, energy drink perception, weight status and sociodemographic characteristics in a school-going sample of Pacific adolescents.

DESIGN

A cross-sectional study carried out in the schools during school hours between July 2015 and April 2016.

SETTING

Sociodemographic characteristics, weight status, energy drink perception, and quantity of energy drinks consumed were obtained. Chi-square tests of independence, independent t tests, multivariate logistic regressions and multiple linear regressions were used.

SUBJECTS

A representative sample of 678 New Caledonian adolescents (11-16 years).

RESULTS

We found that one third of New Caledonian adolescents consume energy drinks. Boys are more likely to drink them than girls and Polynesians drink significantly more than European and Melanesian adolescents. Higher energy drink consumption in the New Caledonian adolescents is associated with good or neutral perceptions of the energy drink impact on health. Moreover, sex (being male) significantly influences the total energy drink consumption per week. Energy drink consumers have a tendency toward better perceptions of energy drinks than non-consumers.

CONCLUSIONS

Nutritional education targeting energy drink consumers should take these results into account by providing (community-based) educational programs, especially for adolescents from low socioeconomic backgrounds, boys, or those living in rural areas.

Sugar-Sweetened Beverage Consumption and Associated Factors in School-Going Adolescents of New Caledonia

This cross-sectional study assessed sugar-sweetened beverage (SSB) consumption and its associations with the sociodemographic and physical characteristics, behavior and knowledge of New Caledonian adolescents. The survey data of 447 adolescents from ages 11 to 16 years were collected in five secondary public schools of New Caledonia between July 2015 and April 2016. These data included measured height and weight, SSB consumption, sociodemographic characteristics, body weight perception, physical activity, and knowledge (sugar quantity/SSB unit; energy expenditure required to eliminate a unit) and opinions about the SSB‒weight gain relationship. Ninety percent of these adolescents declared regularly drinking SSBs. Quantities were associated with living environment (1.94 L·week⁻¹ in urban environment vs. 4.49 L·week⁻¹ in rural environment, p = 0.001), ethnic community (4.77 L·week⁻¹ in Melanesians vs. 2.46 L·week⁻¹ in Caucasians, p < 0.001) and knowledge about energy expenditure (6.22 L·week⁻¹ in unknowledgeable adolescents vs. 4.26 L·week⁻¹ in adolescents who underestimated, 3.73 L·week⁻¹ in adolescents who overestimated, and 3.64 L·week⁻¹ in adolescents who correctly responded on the energy expenditure required to eliminate an SSB unit, p = 0.033). To conclude, community-based health promotion strategies should (1) focus on the physical effort needed to negate SSB consumption rather than the nutritional energy from SSB units and (2) highlight how to achieve sustainable lifestyles and provide tools for greater understanding and positive action.

Nutrition behaviors and sociodemographic factors associated with overweight in the multi-ethnic adolescents of New Caledonia

Objectives: New Caledonia is a multi-ethnic French territory in the Pacific, characterized by communities with widely varying nutritional habits. Little is currently known about adolescent food behaviors and habits and their association with overweight. This study therefore determined the sociodemographic factors and food behaviors associated with overweight and underweight in this population, as well as the factors associated with skipping breakfast. Methods: A cross-sectional survey was conducted among New Caledonian adolescents using a self-administered questionnaire; anthropometric measurements were also taken. Weight status was determined using international cutoffs, and the factors associated with overweight and underweight were identified with multiple logistic regression analysis. The factors associated with breakfast skipping were also determined. Results: Skipping breakfast, being Melanesian, living in a rural area and having low economic status were positively associated with overweight in these adolescents. Skipping breakfast was relatively infrequent, reported by 18% and 13% of the males and females, respectively. Logistic regression models found that the main factors associated with breakfast consumption habits were gender, weight status and ethnicity. Conclusions: Several factors are associated with overweight status in New Caledonian adolescents. Breakfast education should be improved for adolescents living in rural areas and from low socioeconomic status.

Relationship of body fat and body mass index in young Pacific Islanders: a cross-sectional study in European, Melanesian and Polynesian groups

BACKGROUND

Body mass index is the most often used indicator of obesity but does not distinguish between lean and fat mass. Adiposity at the same body mass index differs across ethnic groups.

OBJECTIVES

The twofold aim of this study was to determine whether body mass index (BMI)-based references are correlated with body fat percentage (%BF) in a pluri-ethnic population of Pacific Islanders and to assess the diagnostic accuracy of these references by using the percentage of body fat as the gold standard.

METHODS

Height and weight were obtained, and triceps and subscapular skinfold thicknesses were measured in a sample of 796 adolescents (11-16 years) from the three main ethnic groups in New Caledonia: Melanesian, European and Polynesian. %BF was derived from the Slaughter equations, and BMI z score was calculated by using various international and national references.

RESULTS

Melanesian teens had lower %BF compared with their European counterparts for the same BMI z score. Whatever the BMI-based reference used to detect overfatness (%BF >25% for boys and >30% for girls), sensitivity was higher in Melanesian adolescents, while specificity was higher in their European counterparts. Diagnostic accuracy was better in Melanesian compared with European adolescents.

CONCLUSIONS

This study shows that Melanesian adolescents have lower %BF than their European counterparts for the same BMI z score. Therefore, the diagnostic accuracy of BMI to detect overfatness is related to ethnicity. Whatever the BMI-based reference, sensitivity was higher in the Melanesian group, while specificity was higher in the European group.

Potential for waist-to-height ratio to detect overfat adolescents from a Pacific Island, even those within the normal BMI range

INTRODUCTION

Waist-to-height ratio (WHtR) is a simple anthropometric proxy for central body fat; it is easy to use from a health education perspective. A WHtR value >0.5 has been proposed as a first level indicator of health risk. The first aim of this study was to compare WHtR with values based on body mass index (BMI) in their prediction of the percentage of body fat (%BF) in a multi-ethnic population of adolescents from New-Caledonia (age 11-16year). Secondly, to see whether WHtR >0.5 could be used to detect overfat subjects whose BMI was in the normal range.

MATERIALS AND METHODS

Body fat percentage (%BF, based on skinfold measurements), BMI and WHtR were calculated for New Caledonian adolescents from different ethnic backgrounds. The relationship between %BF, BMI and WHtR was determined using quadratic models and from linear regression equations. The sensitivity and specificity of WHtR for detecting overfat adolescents (%BF >25% in boys and >30% in girls) were assessed and compared with those from the BMI-based classification.

RESULTS

WHtR showed better correlation with %BF than BMI-based measurements. WHtR >0.5 was also more accurate than BMI in detecting overfat adolescents. Moreover, using this boundary value, 8% of adolescents in the normal BMI range were shown to be over-fat.

CONCLUSIONS

WHtR is a good anthropometric proxy to detect overfat adolescents. Detecting overfat adolescents within the normal BMI range is particularly important for preventing non communicable diseases. We therefore recommend using WHtR for health education programs in the Pacific area and more generally.

Anthropometric Characteristics and Physical Fitness in Rural and Urban 11- to 16-Year-Old Melanesian Adolescents: A Cross-sectional Study in New Caledonian Schools

We evaluated anthropometric characteristics and physical fitness in 556 Melanesian adolescents from rural and urban New Caledonia to build health education programs focused on physical activity. In 2013, body weight, height, skinfold thickness, lean body mass (LBM), percentage fat body mass (%FBM), physical fitness (power, agility, speed, maximal aerobic speed [MAS], estimated VO_2max), and self-reported physical activity were assessed. Rural adolescents were significantly shorter and faster, had lower weight, %FBM, LBM, and power output and similar MAS and VO_2max, and were more active than urban adolescents. Rural girls were significantly shorter, had higher MAS and VO_2max, and were faster and significantly more active than urban girls while similar %BFM was observed in both groups of girls. Rural boys showed significantly lower height, weight, %FBM, and power and were significantly faster and more active than urban boys. In conclusion, rural Melanesian adolescents are more active, with good physical fitness (especially boys), although high %FBM was noted (especially in girls).

Self-Reported Height and Weight in Oceanian School-Going Adolescents and Factors Associated With Errors

We examined the accuracy of self-reported weight and height in New Caledonian school-going adolescents. Self-reported and measured height and weight data were collected from 665 adolescents of New Caledonia and were then compared. Multivariable logistic regressions identified the factors associated with inaccurate self-reports. Sensitivity and specificity of self-reported body mass index values to detect overweight or obesity were evaluated. Self-reported weight was significantly lower than measured weight (boys, -3.56 kg; girls, -3.13 kg). Similar results were found for height (boys, -2.51 cm; girls, -3.23 cm). Multiple regression analyses indicated that the difference between self-reported and measured height was significantly associated with ethnicity and pubertal status. Inaccurate self-reported weight was associated with socioeconomic status, place of residence, body-size perception and weight status. Screening accuracy of self-reported body mass index was low, particularly in the Melanesian subgroup. These findings should be considered when overweight is estimated in the Melanesian adolescent population at individual scale.

Misperception of weight status in the pacific: preliminary findings in rural and urban 11- to 16-year-olds of New Caledonia

Background

Adolescent obesity is prevalent in Pacific region ethnic groups (European, Melanesian and Polynesian) living in both urban and rural areas. Although body perception is an important factor of weight gain or loss, little is known about the body self-perceptions of Pacific region adolescents. This study therefore evaluated adolescent perceptions of body weight according to ethnicity (European, Melanesian or Polynesian), socioeconomic status (low, intermediate or high) and living area (rural or urban) in New Caledonia.

Methods

Sociodemographic and anthropomorphic data from 737 adolescents (351 boys and 386 girls) with ages ranging from 11 to 16 years were collected and analysed. The International Obesity Task Force (IOTF) standards were used to define weight status as normal-weight, underweight or overweight/obese. Weight perception was assessed from detailed questionnaires, with adolescents rating their own weight with the following descriptors: ‘about the right weight’, ‘too heavy’, or ‘too light’.

Results

Results showed that only 8.5% of normal-weight adolescents (7% boys and 10% girls) identifying themselves as ‘too heavy’. Normal-weight Melanesian adolescents were less likely than their European counterparts to assess themselves as too heavy (OR = 0.357). However, half the overweight/obese adolescents underestimated their weight status (53% boys and 48% girls). Weight misperception was associated with ethnicity, socioeconomic status and living area, with gender-specific differences.

Conclusions

The results of this study suggest that these sociodemographic factors should be taken into account when designing public health policies and health education school programmes in New Caledonia and, more broadly, the Pacific region.

Intensity, recovery kinetics and well-being indices are not altered during an official FIFA futsal tournament in Oceanian players

Physiological responses (intensity and recovery kinetics) and well-being indices were examined during a 4-day FIFA international tournament. Ten outfield New Caledonian players (age: 25.5 ± 3.8 years; height: 170 ± 7 cm; weight: 70.7 ± 8.6 kg) were assessed during the four matches. Players' aerobic and anaerobic capacities were measured before the tournament while heart rate (HR), intra-matches recovery and well-being indices (Hooper index) were measured throughout the tournament. HR (168 ± 8 bpm), exercise intensity (83.4 ± 2.3% of HR reserve) and recovery indices were similar throughout the tournament. Well-being indices were largely alike during the tournament while rating of perceived exertion increased throughout the tournament that was not associated with HR or well-being indices. High aerobic and anaerobic capacities were associated with high match intensities and slow recovery indices. In summary, match intensity assessed by HR, recovery kinetics and well-being of Oceanian futsal players were not modified during a 4-day FIFA futsal tournament. Assessment of aerobic and anaerobic capacities may be useful to select players for optimal performance during this type of international tournament.

Anthropometric and physiological characteristics of Melanesian futsal players: a first approach to talent identification in Oceania

This study assessed the anthropometric and physiological characteristics of elite Melanesian futsal players in order to determine the best performance predictors. Physiological parameters of performance were measured in 14 Melanesian (MEL-G, 24.4±4.4 yrs) and 8 Caucasian (NMEL-G, 22.9±4.9) elite futsal players, using tests of jump-and-reach (CMJ), agility (T-Test), repeated sprint ability (RSA), RSA with change-of-direction (RSA-COD), sprints with 5 m, 10 m, 15 m, and 30 m lap times, and aerobic fitness with the 30-15 intermittent fitness test (30-15 IFT). The anthropometric data revealed significantly lower height for MEL-G compared with NMEL-G: 1.73±0.05 and 1.80±0.08 m, respectively; P = 0.05. The CMJ was significantly higher for MEL-G than NMEL-G: 50.4±5.9 and 45.2±4.3 cm, respectively; P = 0.05. T-Test times were significantly lower for MEL-G than NMEL-G: 10.47±0.58 and 11.01±0.64 seconds, respectively; P = 0.05. MEL-G height was significantly related to CMJ (r = 0.706, P = 0.01), CMJ_peakP (r = 0.709, P = 0.01) and T-Test (r = 0.589, P = 0.02). No significant between-group differences were observed for sprint tests or 30-15 IFT, including heart rate and estimated VO_2max. Between groups, the percentage decrement (%Dec) in RSA-COD was significantly lower in MEL-G than NMEL-G (P = 0.05), although no significant difference was noted between RSA and RSA-COD. Within groups, no significant difference was observed between %Dec in RSA or RSA-COD; P = 0.697. This study presents specific anthropometric (significantly lower height) and physiological (significantly greater agility) reference values in Melanesians, which, taken together, might help coaches and physical fitness trainers to optimize elite futsal training and talent identification in Oceania.

Remote magnetic actuation of micrometric probes for in situ 3D mapping of bacterial biofilm physical properties

Bacterial adhesion and growth on interfaces lead to the formation of three-dimensional heterogeneous structures so-called biofilms. The cells dwelling in these structures are held together by physical interactions mediated by a network of extracellular polymeric substances. Bacterial biofilms impact many human activities and the understanding of their properties is crucial for a better control of their development - maintenance or eradication - depending on their adverse or beneficial outcome. This paper describes a novel methodology aiming to measure in situ the local physical properties of the biofilm that had been, until now, examined only from a macroscopic and homogeneous material perspective. The experiment described here involves introducing magnetic particles into a growing biofilm to seed local probes that can be remotely actuated without disturbing the structural properties of the biofilm. Dedicated magnetic tweezers were developed to exert a defined force on each particle embedded in the biofilm. The setup is mounted on the stage of a microscope to enable the recording of time-lapse images of the particle-pulling period. The particle trajectories are then extracted from the pulling sequence and the local viscoelastic parameters are derived from each particle displacement curve, thereby providing the 3D-spatial distribution of the parameters. Gaining insights into the biofilm mechanical profile is essential from an engineer's point of view for biofilm control purposes but also from a fundamental perspective to clarify the relationship between the architectural properties and the specific biology of these structures.

Sequential exercise in triathletes: variations in GH and water loss

Growth hormone (GH) may stimulate water loss during exercise by activating sweating. This study investigated GH secretion and water loss during sequential cycling and running, taking postural changes into account. The two exercise segments had similar durations and were performed at the same relative intensity to determine their respective contributions to water loss and the plasma volume variation noted in such trials. Eight elite triathletes first performed an incremental cycle test to assess maximal oxygen consumption. Then, the triathletes performed one of two trials in randomized order: constant submaximal cycling followed by treadmill running (C₁-R₂) or an inversed succession of running followed by cycling (R₁-C₂). Each segment of both trials was performed for 20 minutes at ∼75% of maximal oxygen consumption. The second trial, reversing the segment order of the first trial, took place two weeks later. During cycling, the triathletes used their own bicycles equipped with a profiled handlebar. Blood sampling (for GH concentrations, plasma viscosity and plasma volume variation) was conducted at rest and after each segment while water loss was estimated from the post- and pre-measures. GH increases were significantly lower in R₂ than C₂ (72.2±50.1 vs. 164.0±157 ng.ml⁻¹.min⁻¹, respectively; P<0.05). Water loss was significantly lower after C₁-R₂ than R₁-C₂ (1105±163 and 1235±153 ml, respectively; P<0.05). Plasma volume variation was significantly negative in C₁ and R₁ (−6.15±2.0 and −3.16±5.0%, respectively; P<0.05), not significant in C₂, and significantly positive for seven subjects in R₂ (4.05±3.1%). We concluded that the lower GH increases in R₂ may have contributed to the smaller reduction in plasma volume by reducing sweating. Moreover, this lower GH response could be explained by the postural change during the transition from cycling to running. We recommend to pay particular attention to their hydration status during R₁ which could limit a potential dehydration during C₂.

Relationships between heart rate and physiological parameters of performance in top-level water polo players

The aim of this study was to measure the heart rate (HR) response of eight elite water polo players during the four 7-min quarters of the game and to check for relationships with the physiological parameters of performance ([Formula: see text]O2max, Th1vent, Th2vent). Each athlete performed a [Formula: see text]O2max treadmill test and played a water polo game wearing a heart rate monitor. The game fatigue index was calculated as the ratio of the fourth-quarter HR to the first-quarter HR: HR4/HR1. The results showed a slight decrease in fourth-quarter HR compared with the first quarter, with the mean four-quarter HR equal to 79.9±4.2% of HRmax. Stepwise multiple regression analysis showed [Formula: see text]O2max to be the main explanatory factor of game intensity, i.e. game HR expressed in %HRreserve (R=0.88, P<0.01). We observed that higher aerobic capacity resulted in higher game intensity. We also observed a decrease in the playing intensity in the fourth quarter compared with the first, likely due to very high game involvement. We concluded that high aerobic capacity seems necessary to ensure high game intensity in water polo. This suggests that coaches should encourage their athletes to reach a minimum level of [Formula: see text]O2max and that HR monitoring could be of great interest in the control of water polo training sessions.

Mapping of bacterial biofilm local mechanics by magnetic microparticle actuation

Most bacteria live in the form of adherent communities forming three-dimensional material anchored to artificial or biological surfaces, with profound impact on many human activities. Biofilms are recognized as complex systems but their physical properties have been mainly studied from a macroscopic perspective. To determine biofilm local mechanical properties, reveal their potential heterogeneity, and investigate their relation to molecular traits, we have developed a seemingly new microrheology approach based on magnetic particle infiltration in growing biofilms. Using magnetic tweezers, we achieved what was, to our knowledge, the first three-dimensional mapping of the viscoelastic parameters on biofilms formed by the bacterium Escherichia coli. We demonstrate that its mechanical profile may exhibit elastic compliance values spread over three orders of magnitude in a given biofilm. We also prove that heterogeneity strongly depends on external conditions such as growth shear stress. Using strains genetically engineered to produce well-characterized cell surface adhesins, we show that the mechanical profile of biofilm is exquisitely sensitive to the expression of different surface appendages such as F pilus or curli. These results provide a quantitative view of local mechanical properties within intact biofilms and open up an additional avenue for elucidating the emergence and fate of the different microenvironments within these living materials.

The effect of a silicone swim cap on swimming performance in tropical conditions in pre-adolescents

We tested whether the silicone swim caps (SC) worn by young swimmers in a tropical climate negatively influence aerobic performance. Nine trained pre- adolescents [11.8 (± 0.8) years] swam randomized 800-m trials (water: 32.9°C, outdoors: shade, 29.2 ± 0.2 °C, 74 ± 0.3 % rh) with a SC or a nude head (NH). Performance times and heart rate (HR) were monitored continuously. Rectal temperature (Trec) was measured before and after trials. The rating of perceived exertion (RPE) was assessed. Stroke frequency (SF), stroke length (SL) and stroke index (SI) were measured every 50-m. The SC trial was significantly longer than NH (799 ± 16 and 781 ± 16 seconds, respectively). Mean delta Trec was significantly greater in SC (0.2 ± 0.1°C vs. -0.1 ± 0.1°C in SC vs. NH), mean SI was significantly different in SC versus NH (1.83 ± 0.07 vs 1.73 ± 0.06); but RPE and mean HR, SF and SL showed no change. We conclude that a silicone swim cap worn in tropical environment significantly decreased 800-m crawl performance without affecting HR or RPE. Silicone swim caps worn by young swimmers in a tropical environment may also have negative effects on training capacity. Key pointsSwimming in tropical climate represents a physiological stressSwimming with swim cap in warm water could induce thermal stressThermoregulation processes have to be used in order to make training in tropical climate safer.

Continuous lipase-catalyzed production of esters from crude high-oleic sunflower oil

The objective of this work was to develop an economically relevant enzymatic process of butyl ester production using crude high-oleic sunflower oil. Novozym 435, a non-regiospecific biocatalyst, provided the best compromise between activity and butyl-ester yield. The inhibition caused by the presence of phopholipids in crude oil was eliminated by using tert-butanol. It demonstrates the key role of the medium polarity in order to insure the stability of a process. Initial substrate concentrations and their molar ratio were optimized in a continuous packed-bed reactor to maximize product yield and productivity. The best compromise was obtained for an initial oil concentration of 500 mM and a molar ratio of 5. It enabled a high productivity of 13.8 tons year(-1)kg Novozym 435(-1) with a butyl-ester purity of 96.5% to be obtained. Experiments with the continuous reactor were performed over 50 days without any loss of enzyme activity.

Effects of the TP53 p.R249S mutant on proliferation and clonogenic properties in human hepatocellular carcinoma cell lines: interaction with hepatitis B virus X protein

Aflatoxin B(1) (AFB(1)) is a risk factor for hepatocellular carcinoma (HCC) in many low-resource countries. Although its metabolites bind at several positions in TP53, a mutation at codon 249 (AGG to AGT, arginine to serine, p.R249S) accounts for 90% of TP53 mutations in AFB(1)-related HCC. This specificity suggests that p.R249S confers a selective advantage during hepatocarcinogenesis. Using HCC cell lines, we show that p.R249S has lost the capacity to bind to p53 response elements and to transactivate p53 target genes. In p53-null Hep3B cells, stable transfection of p.R249S or of another mutant, p.R248Q, did not induce significant changes in cell proliferation and survival after cytotoxic stress. In contrast, in a cell line that constitutively expresses both p.R249S and the hepatitis B virus antigen HBx (PLC/PRF/5), silencing of either p.R249S or HBx by RNA interference slowed down proliferation, with no additive effects when both factors were silenced. Furthermore, the two proteins appear to form a complex. In human HCC samples, mutation at codon 249 did not correlate with p.R249S protein accumulation or HBx truncation status. We suggest that p.R249S may contribute to hepatocarcinogenesis through interaction with HBx, conferring a subtle growth advantage at early steps of the transformation process, but that this interaction is not required for progression to advanced HCC.

Anthropometrical and Physiological Determinants of Performance in French West Indian Monofin Swimmers: A First Approach

To characterise the anthropometrical and physiological parameters of French West Indian monofin swimmers, seven French West Indian male competitors underwent anthropometrical measurements and physiological testing. The results were analysed in relation with their performances during national and international events (from 50- to 1500-m). We found that both anthropometrical and physiological (aerobic and anaerobic components) factors contributed to the performances of these swimmers. The results demonstrated that certain parameters consistently contributed to the global performance: aerobic parameters (maximal oxygen uptake and the second ventilatory threshold, R (2) = 0.72 and 0.69, respectively), anaerobic parameters (power obtained with the counter-movement jump [R (2) = 0.58] and the force-velocity test [R (2) = 0.54]), leg volume (V1, R (2) = 0.54) and perimeter (P1, R (2) = 0.64), and fat and lean body mass (R (2) = 0.76 and 0.62, respectively). Further studies are needed to compare these determinants of performance in French West Indian and European swimmers and to investigate how they contribute to swimming technique.

Exercise intensity during repeated days of racing in professional triathletes

The purpose of this study was to estimate the exercise intensity from the competition heart rate (HR) of professional triathletes during a multi-triathlon race. Five internationally ranked professional triathletes completed incremental cycling and running tests to assess the first and second ventilatory thresholds (i.e., VT and RCT) and the HR at VT and RCT. HR was then monitored during a 5 d multi-triathlon race: a prologue time trial (PTT, 0.2 km swim -- 5 km cycle -- 1.2 km run) that opened the race; short-distance triathlons (SHD; 1.3 km swim -- 36 km cycle -- 8.4 km run) performed on the 2nd and 5th days; and sprint-distance triathlons (SPD; 0.75 km swim -- 20 km cycle -- 5 km run) performed on the 3rd and 4th days. All trials except the last (i.e., the second SHD) were performed above HR corresponding to RCT. PTT elicited significantly higher mean HR than the other trials (except for the first SPD trial). In contrast, the last SHD elicited significantly lower HR than the other trials. These responses were globally similar in the 3 segments (i.e., swim, cycle, and run). This study demonstrates that the triathletes performed at very high intensity during a drafting-permitted multi-triathlon race. However, as shown for multi-day cycling distances, the HR responses depended on (i) the distance covered and (ii) group behavior.

Is exercise-induced arterial hypoxemia in triathletes dependent on exercise modality?

To determine whether exercise modality affects arterial hypoxemia (EIAH) during training-intensity exercise, 13 triathletes performed 20 min of cycling (C) followed by 20 min of running (R): C-R, and two weeks later, 20 min of R followed by 20 min of C:R-C. Each trial was performed at an intensity slightly above the ventilatory threshold and close to the daily training intensity (75 % of VO2max). Ventilatory data were collected continuously using an automated breath-by-breath system. Partial pressure of oxygen in arterial blood (PaO2) was measured after each C and R segment and arterial oxyhemoglobin saturation (SpO2) was monitored continuously via pulse oximetry. The metabolic rate was similar across modalities and trials, i.e., C-R (53.8 +/- 3.8 vs. 51.1 +/- 5.3 ml.min(-1).kg(-1)) and R-C (52.2 +/- 4.5 vs. 53.2 +/- 4.6 ml.min(-1).kg (-1)). EIAH showed significantly greater severity for R compared to C irrespective of the order (p < 0.05 for both trials). R values of PaO2 (and SpO2) for C-R and R-C were 88.7 +/- 6.0 mm Hg (93.0 +/- 0.6 % SpO2) and 86.6 +/- 7.3 mm Hg (93.5 +/- 0.6 % SpO2) and C values were 93.7 +/- 8.4 mm Hg (95.4 +/- 0.4 % SpO2) and 91.4 +/- 5.4 mm Hg (94.8 +/- 0.3 % SpO2). R ventilatory data described a significantly different breathing pattern than C, with higher respiratory rate (35.9 b.min(-1) vs. 51.1 b.min(-1) for C-R, p < 0.01; and 50.0 b.min(-1) vs. 41.5 b.min(-1) for R-C, p < 0.01) and lower tidal volume (2636 ml vs. 2282 ml for C-R, p < 0.02 and 2272 ml vs. 2472 ml for R-C, p < 0.05). We concluded that EIAH was greater during running than cycling for a similar metabolic rate corresponding to training intensity and that EIAH could thus be considered dependent on exercise modality.

Blood Rheological Responses to Running and Cycling: A Potential Effect on the Arterial Hypoxemia of Highly Trained Athletes?

To investigate 1) the blood rheological responses to high training volume and 2) the potential effect of these responses on arterial hypoxemia induced during submaximal running and cycling, 10 triathletes performed an incremental cycle test, 20 minutes of running (R), and 20 minutes of cycling (C). All trials were performed at nearly 75 % of VO2max. Hematocrit (H), blood viscosity (etab), plasma viscosity (etapl), index of erythrocyte rigidity (Tk), changes in plasma volume (DeltaPV), pulmonary diffusing capacity (DLco), and arteriolized blood gas (PaO2) were measured before and after each trial. Pulse oxymetry (SpO2) and cardioventilatory data were collected continuously. A significant increase in etab, etapl, and H was noted after R and C with respect to pre-exercise, whereas DeltaPV decreased, with a greater decrease after C. Tk was significantly higher after R than after C. A significantly greater drop in DLco was noted after C compared with R. SpO2 decreased significantly more during R, as did PaO2. We conclude that blood rheological responses are specific to running and cycling. Cycling induced a sharp decrease in plasma volume, which could partially explain the greater DLco alteration. Running was characterized by an increase in Tk, which could be implicated in the severity of the drop in arterial oxygenation observed.

Field and laboratory testing in young elite soccer players

AIM

To determine if there are correlations between the physical fitness of young soccer players assessed by field and laboratory testing.

METHODS

Thirty four male soccer players took part in the study (mean (SD) age 17.5 (1.1) years, height 177.8 (6.7) cm, weight 70.5 (6.4) kg). Maximal oxygen uptake (VO(2)MAX) during treadmill running and vertical jump height on a force platform were measured in the laboratory. Field tests consisted of a soccer specific endurance test (Bangsbo test) and 30 m sprint with 10 m lap times.

RESULTS

The Bangsbo test correlated with the lowest velocity associated with VO(2)MAX (vVO(2)MAX; R(2) = 0.55, p<0.001), but not with VO(2)MAX. Sprint times at 30 m and 20 m were related to peak extension velocity and peak extension force measured during vertical jumping, but not to vertical jump height per se. The jumping force and velocity could explain 46% of the 30 m sprint performance (R(2) = 0.46, p<0.001).

CONCLUSION

The Bangsbo test and 30 m sprint test correlate with vVO(2)MAX and vertical jump force and velocity respectively. The Bangsbo test does not give a good estimate of VO(2)MAX in young soccer players.

Application of a specific and sensitive radiometric assay for microbial lipase activities in marine water samples from the lagoon of nouméa

Marine microbiologists commonly assay lipase activities by using a synthetic fluorescent analog, 4-methylumbelliferyl (MUF)-oleate. The technique is convenient, but it is considered to be unspecific because of the structure of this analog. This study reports the design of a new specific and sensitive lipase assay based on the use of a radiolabeled triglyceride, [3H]triolein. Free fatty acids (FFA) resulting from its hydrolysis are isolated as a function of time in a one-step liquid-liquid extraction and then radioassayed. MUF-oleate and [3H]triolein techniques were compared by measuring lipase activities at similar substrate concentrations along a trophic gradient in the Southwest Lagoon of New Caledonia, near Nouméa. Hydrolysis rates decreased from the nearshore station to the offshore station and showed similar trends regardless of the technique used. Rates decreased from 5.83 to 0.88 nmol of FFA. liter-1. h-1 and from 0.76 to 0.23 nmol of 3H-FFA. liter-1. h-1, respectively. These results appeared to be consistent with bacterial production results, which also decreased similarly (from 0.59 to 0.26 micrograms of C. liter-1. h-1). However, the ratio of MUF-oleate activities to [3H]triolein activities, which was constant at the offshore stations (3.8 +/- 0.1), gradually increased at the nearshore stations (from 4.1 to 7.6). This result shows that the two assays respond in different ways to changes in environmental conditions and validates the need to set up more specific enzymatic assays.

Competitive Season of Triathlon Does not Alter Bone Metabolism and Bone Mineral Status in Male Triathletes

This longitudinal study evaluated the effects of a triathlon season on bone metabolism and hormonal status. Seven male competitive triathletes (mean age 19.3 years, range 18 - 20) with 5.0 +/- 0.3 years of competition experience were tested twice during the season: at the beginning of training and 32 weeks later. Total and regional bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry, while bone turnover was evaluated by specific biochemical markers: bone-specific alkaline phosphatase (B-ALP), osteocalcin, and urinary type I collagen C-telopeptide. In addition, sexual, calciotropic and somatotropic hormones were also analyzed. After 32 weeks, a BMD increase was found at the lumbar spine (1.9 %; p = 0.031) and skull (3.1 %; p = 0.048), while no variation was observed for total body or at the proximal femur. The B-ALP level decreased (-23.2 %; p = 0.031), but no variation was found for the other bone markers. 1.25 (OH) (2)D3, IGF-1 and the bioavailability IGF-1 index (IGF-1/IGFBP-3) increased by 18.3 % (p = 0.047), 29 % (p = 0.048), 33 % (p = 0.011), respectively, while PTH, testosterone, IGFBP-3 and cortisol concentrations were unchanged. In conclusion, the triathlon season had a moderately favourable effect on BMD, although a slowing down of bone formation activity was observed. No variation in hormonal levels was observed that could have limited the effects of exercise on bone tissue.

Effects of successive running and cycling on the release of atrial natriuretic factor in highly trained triathletes

AIM

To evaluate the influence of successive running and cycling on both exercise-induced arterial hypoxemia (EIAH) and atrial natriuretic factor (ANF) release, 5 triathletes performed 2 separate exercise trials.

METHODS

One trial consisted of a 20-min+20-min successive cycle-run exercise (C(1)-R(2)) and the other consisted of a 20-min+20-min successive run-cycle exercise (R(1)-C(2)). Arterial oxygenation (PaO(2)) and ANF were determined at pre-exercise, at the end of each 20-min segment of exercise and after 10 min of recovery.

RESULTS

EIAH was noted during C(1)-R(2) and R(1)-C(2) trials. A higher EIAH was observed during running compared with cycling performed in the 1(st) position (R(1) vs C(1)) in the succession. In contrast, no difference was observed between successive running and successive cycling (R(2) vs C(2)), (-10.6+/-7.0 vs -15.6+/-4.0 mmHg for C(1)-R(2) and -20.9+/-6.0 vs -16.2+/-2.4 mmHg for R(1)-C(2)). ANF showed no difference between cycling and running performed in first position, whereas a significantly lower ANF was observed during successive cycling compared with successive running (C(2) vs R(2)) (19.9+/-3.72 vs 36.2+/-6.4 pmol.L(-1)). During recovery, neither PaO(2) nor ANF plasma returned to baseline level after either trial.

CONCLUSION

This study provides new information on some of the physiological modifications that occur during multi-sports. Specifically, the impact of the modality of the successive exercise on ANF release and body fluid regulation was observed. Cycling as the successive exercise seems to cause lower ANF release than does running.

Effects of 8 days acclimation on biological and performance response in a tropical climate

BACKGROUND

This study was designed to determine the acclimation process elicited by exposure to a tropical climate.

METHODS

Nine triathletes performed 3 outdoor indirect continuous running multistage tests in both thermoneutral and tropical conditions. Before travelling to the tropical area (Martinique Island, FWI), the triathletes performed the thermoneutral test (TN) in 14 degrees C and 45% rh conditions. The tropical tests were performed 2 and 8 days after arrival (T2 and T8, performed at a mean environmental temperature of 33.4 degrees C and 75.5% rh). The day before T8, blood samples were drawn for biochemical analysis. During each test, tympanic temperature, sweat rate, weight loss, heart rate (HR), and performance were recorded.

RESULTS

The results demonstrated that: 1) the mean tympanic temperature was greater in T2 (p<0.001) and T8 (p<0.01) than in TN; 2) the mean sweat rate was significantly greater (p<0.001) in T2 and T8 than in TN and significantly greater in T8 than in T2 (p<0.03); 3) the weight loss after trials was significantly greater (p<0.001) in T2 and T8 than in TN and in T8 than in T2 (p<0.04); 4) the mean HR and the HR at rest were significantly greater in T2 than in TN (p<0.001) and T8 (p<0.005); 6) significant reductions were observed in T8 vs TN in red cell count (p<0.05) and plasma proteins (p<0.04), the consequence of a 7.5% plasma volume expansion; and 7) the performance was significantly lower in both T2 (p<0.02) and T8 (p<0.03) than in TN.

CONCLUSIONS

We concluded that 8 days exposure to hot/wet conditions induced impairments in physiological responses and performance that were still evident on the 8th day. Further and longer outdoor studies are needed to investigate if return to optimal performance levels after adaptation to hot/wet conditions is possible.

Effects of the order of running and cycling of similar intensity and duration on pulmonary diffusing capacity in triathletes

To study the pathophysiological mechanisms involved in the decrease of post-triathlon diffusing capacity (DLco), blood rheologic properties (blood viscosity: eta(b); changes in plasma volume: deltaPV) and atrial natriuretic factor (ANF) were assessed in ten triathletes during cycle-run (CR) and run-cycle (RC) trials at a metabolic intensity of 75% of maximal oxygen consumption ( VO(2max)). The DLco was measured before and 10 min after trials. ANF and deltaPV were measured at rest, after the cycle and run of CR and RC trials, and at the end of and 10 min after exercise. RC led to a greater deltaDLco decrease, a lower ANF concentration and a lower deltaPV than did CR, whereas for both CR and RC eta(b) was increased throughout exercise and 10 min after. In addition, after CR the deltaDLco decrease was inversely correlated ( r=-0.764; P<0.01) with deltaPV. The association of decreased plasma volume, increased eta(b), and lower ANF concentrations after RC suggested that lower blood pulmonary volume may have caused the greater decrease in Dlco as compared with CR. The inverse correlation between deltaPV and deltaDLco reinforces the hypothesis that fluid shifts limit the post-exercise DLco decrease after the CR succession in triathletes. Lastly, cycling in the crouched position might increase intra-thoracic pressure, decrease thorax volume due to the forearm position on the handlebars, and weaken peripheral muscular pump efficacy, all of which would limit venous return to the heart, and thus result in low pulmonary blood volume. Compared with cycling, running appeared to induce the opposite effects.