Assessing the impact of road traffic on cycling for leisure and cycling to work

Background

This study investigated the associations of physical characteristics and personality in adolescence with physical activity and sedentary behaviour in adulthood.

Findings

Physical characteristics (i.e. objectively measured BMI, sum of skin folds, MOPER test battery performance), and personality (i.e. self-reported inadequacy, social inadequacy, rigidity, self-sufficiency/recalcitrance, dominance, achievement motivation, facilitating anxiety, debilitating anxiety, and social desirability) were assessed in 217 adolescent boys (Mean 13.0, SD 0.6) and girls (Mean 12.9, SD 0.6). Twenty-nine years later, at the age of 42, their physical activity and sedentary behaviour were assessed by means of accelerometry. Boys who scored lower on self-sufficiency/recalcitrance and higher on facilitating anxiety spent more time sedentary in adulthood. Girls with a superior standing high jump performance, and a lower score on social desirability spent more time sedentary in adulthood. In contrast with sedentary behaviour, physical activity at age 42 year could not be predicted by physical characteristics or personality in adolescence.

Conclusions

Sedentary behaviour in adulthood was partly explained by physical characteristics and/or personality in adolescence. Thus, our results suggest that it may be possible to identify people who are at risk of becoming sedentary at a rather young age.     

Effects of weight cycling induced by diet cycling in rats differing in susceptibility to dietary obesity

OBJECTIVE: Although the majority of evidence in rodents does not support the view that weight cycling (consisting of bouts of food restriction and refeeding) promotes obesity, the effects of weight cycling on body weight regulation remain controversial. We have previously demonstrated that some rats within a strain are more susceptible to develop obesity than others when given free access to a high-fat diet. In this study, we tested the hypothesis that rats most susceptible to weight gain on a high-fat diet would also be most susceptible to weight gain as a consequence of weight cycling. RESEARCH METHODS AND PROCEDURES: Rats were provided a low-fat diet (12% corn oil) for 2 weeks, then given a high-fat diet (45% corn oil) for 2 weeks to identify those most (obesity prone) and least (obesity resistant) susceptible to weight gain. Half of each group was then subjected to three 30-day cycles of food restriction (10 days) and refeeding (20 days) [weight cycler (WC) rats]. The other half were allowed free access to the high-fat diet [control (CO) rats]. All rats were then followed for an additional 10 weeks, with free access to the high-fat diet. RESULTS: When considering the entire 160 days of the study, we found no evidence that WC rats relative to CO rats had increased body weight, increased body fat content, or elevated energy efficiency. We found no evidence that rats most prone to dietary obesity were also prone to weight gain after weight cycling. During the weight cycling phase (days 1 to 90), weight cycled groups consumed less energy and gained less weight than controls. During the follow-up phase, WC and CO rats did not differ significantly in weight gain or energy intake. DISCUSSION: In this study, weight cycling did not exacerbate the obesity produced by high-fat diet feeding.     

Putative effects of doping in cycling

After recent scandals in cycling involving doping, it has been asserted that top-level cycling is impossible without pharmacological support. An important prerequisite for successfully completing the Tour de France is maintaining energy balance. To compensate for the daily caloric expenditure of 23-25 MJ, conventional food must be supplemented with liquid food. Quick administration of liquid carbohydrates is essential for optimal recovery of glycogen stores in the liver and skeletal muscle. Androgenic anabolic steroids are a frequently used form of doping. In endurance sports, these drugs have not been shown to affect endurance performance, and there is little evidence to suggest that they enhance recovery. Although epoetin use can increase maximal oxygen uptake, its effects on maximal power output are less pronounced than what is generally assumed. A relationship between haemoglobin concentration and sport performance has not been proved. It has been found that growth hormone rather has a negative than a positive influence on the sport performance. The doping problem is due in part to superstition, hearsay and insufficient knowledge among the athlete's support personnel, which frequently leads to medical malpractice in sport. Education and quality control for sport professionals, including sports physicians, may help to control the doping problem.     

Social-cognitive correlates of risky adolescent cycling behavior

Background  

Bicycle use entails high safety and health risks especially for adolescents. Most safety education programs aimed at adolescents focus on accident statistics and risk perceptions. This paper proposes the investigation of the social-cognitive correlates of risky cycling behaviors of adolescents prior to developing safety education programs.     

The effectiveness of community-based cycling promotion: findings from the <Emphasis Type="Italic">Cycling Connecting Communities</Emphasis>project in Sydney,Australia

Background  

Encouraging cycling is an important way to increase physical activity in the community. The Cycling Connecting Communities (CCC) Project is a community-based cycling promotion program that included a range of community engagement and social marketing activities, such as organised bike rides and events, cycling skills courses, the distribution of cycling maps of the area and coverage in the local press. The aim of the study was to assess the effectiveness of this program designed to encourage the use of newly completed off-road cycle paths through south west Sydney, Australia.     

Gender differences in recreational and transport cycling: a cross-sectional mixed-methods comparison of cycling patterns, motivators, and constraints

ABSTRACT: BACKGROUND: Gender differences in cycling are well-documented. However, most analyses of gender differences make broad comparisons, with few studies modeling male and female cycling patterns separately for recreational and transport cycling. This modeling is important, in order to improve our efforts to promote cycling to women and men in countries like Australia with low rates of transport cycling. The main aim of this study was to examine gender differences in cycling patterns and in motivators and constraints to cycling, separately for recreational and transport cycling. METHODS: Adult members of a Queensland, Australia, community bicycling organization completed an online survey about their cycling patterns; cycling purposes; and personal, social and perceived environmental motivators and constraints (47% response rate). Closed and open-end questions were completed. Using the quantitative data, multivariable linear, logistic and ordinal regression models were used to examine associations between gender and cycling patterns, motivators and constraints. The qualitative data were thematically analyzed to expand upon the quantitative findings. RESULTS: In this sample of 1862 bicyclists, men were more likely than women to cycle for recreation and for transport, and they cycled for longer. Most transport cycling was for commuting, with men more likely than women to commute by bicycle. Men were more likely to cycle on-road, and women off-road. However, most men and women did not prefer to cycle on-road without designed bicycle lanes, and qualitative data indicated a strong preference by men and women for bicycle-only off-road paths. Both genders reported personal factors (health and enjoyment related) as motivators for cycling, although women were more likely to agree that other personal, social and environmental factors were also motivating. The main constraints for both genders and both cycling purposes were perceived environmental factors related to traffic conditions, motorist aggression and safety. Women, however, reported more constraints, and were more likely to report as constraints other environmental factors and personal factors. CONCLUSION: Differences found in men's and women's cycling patterns, motivators and constraints should be considered in efforts to promote cycling, particularly in efforts to increase cycling for transport.     

Maximal accumulated oxygen deficit in running and cycling

The purpose of this study was to compare values of maximal accumulated oxygen deficit (MAOD; a measure of anaerobic capacity) in running and cycling. Twenty-seven women and 25 men performed exhaustive treadmill and cycle ergometer tests of ～3 min, ～5 min, and ～7 min duration. Oxygen demands were estimated assuming a linear relationship between demand and intensity and also using upwardly curvilinear relationships. When oxygen demand was estimated using speed (with exponent 1.05), values for MAOD for the three running tests were virtually identical; the mean of the three values was 78 ± 7 mL·kg?1. Use of an oxygen demand that was estimated using work rate (with exponent 1.00) generated the most similar values for MAOD from the three cycling tests (mean of 59 ± 6 mL·kg?1). Consistent with the higher (p < 0.05) MAOD in running, peak post-exercise blood lactate concentrations were also higher (p < 0.05) in running (13.9 ± 2.2 mmol·L?1) than in cycling (12.6 ± 2.4 mmol·L?1). The results suggest that the relationship between oxygen demand and running speed is upwardly curvilinear for the speeds used to measure MAOD; the relationship between demand and cycle ergometer work rate is linear; MAOD is greater in running than in cycling.     

试论医院顾客价值循环体系中的风轮效应

满足顾客需求的过程实际上就是为顾客创造和传递价值的循环过程,顾客价值决定了顾客满意和顾客忠诚。在顾客价值的循环体系中,由于风轮效应的存在有可能会导致顾客价值在传递过程中的衰减和失效。因此,医院只有持续地为顾客提供高水平的价值,才能获得可靠并持续的顾客满意水平,赢得顾客的忠诚。     

Carbohydrate feedings 1 h before exercise improves cycling performance

The effects of consuming two different amounts of liquid carbohydrate 1 h before exercise on the metabolic responses during exercise and on exercise performance were determined. Subjects consumed either 1.1 g (LC) or 2.2 g (HC) carbohydrate/kg body mass or a placebo (P). Subjects cycled at 70% of maximal oxygen consumption (VO2max) for 90 min and then underwent a performance trial. Blood glucose and insulin responses during exercise were different among the three trials. Total carbohydrate oxidation was greater for the carbohydrate trials compared with P. Time-trial performance was significantly improved by LC and HC. Despite elevated insulin concentrations at the start of and during exercise, and despite an initial drop in blood glucose, consumption of between 1.1 and 2.2 g liquid carbohydrate/kg body mass 60 min before moderately intense prolonged exercise can improve performance, presumably via enhanced carbohydrate oxidation.     

Carbohydrate-electrolyte feedings and 1 h time trial cycling performance

The effects of a commercial sports drink on performance in high-intensity cycling was investigated. Nine well-trained subjects were asked to complete a set amount of work as fast as possible (time trial) following 24 h of dietary (subjects were provided with food, energy 57.4+/-2.4 kcal/kg and carbohydrate 9.1+/-0.4 g/kg) and exercise control. During exercise, subjects were provided with 14 mL/kg of either 6% carbohydrate-electrolyte (CHO-E) solution or carbohydrate-free placebo (P). Results showed that subjects' performances did not greatly improve (time, 62:34+/-6:44 min:sec (CHO-E) vs. 62:40+/-5:35 min:sec (P); average power output, 283.0+/-25.0 W (CHO-E) vs. 282.9+/-29.3 W (P), P > 0.05) while consuming the sports drink. It was concluded that CHO-E consumption throughout a 1-h time trial, following a pre-exercise dietary regimen designed to optimize glucose availability, did not improve time or power output to a greater degree than P in well-trained cyclists.