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The purpose of this study was to investigate the effect of exercise mode on the characteristics of the oxygen uptake (VO(2)) ()response to exercise within the severe intensity domain. Twelve participants each performed a treadmill running test and a cycle ergometer test to fatigue at intensities selected to elicit a mode-specific VO(2)max and to cause fatigue in ~5 min. The tests were at 234 (30) m.min(-1) and 251 (59) W, and times to fatigue were 297 (15) s and 298 (14) s, respectively. The overall rapidity of the VO(2)response was influenced by exercise mode [VO(2)max was achieved after 115 (20) s in running versus 207 (36) s in cycling; p<0.01]. VO(2) responses were fit to a three-phase exponential model. The time constant of the primary phase was faster in treadmill tests than in cycle ergometer tests [14 (6) s versus 25 (4) s; p<0.01], and the amplitude of the primary phase was greater in running than in cycling when it was expressed in absolute terms [2327 (393) ml.min(-1) versus 2036 (301) ml.min(-1); p=0.02] but not when it was expressed as a percentage of the total increase in VO(2) [86 (6)% versus 82 (6)%; p=0.09]. When quantified as the difference between the end-exercise VO(2) and the VO(2) at 2 min, the amplitude of the slow component was ~40% smaller in running [177 (92) ml.min(-1) versus 299 (153) ml min(-1); p=0.03]. It is concluded that exercise modality affects the characteristics of the VO(2) response at equivalent intensities in the severe domain.

BackgroundReduced time dedicated to physical education and free play in recent decades emphasizes the need to promote opportunities for sport participation in adolescents in order to increase physical activity levels. The purpose of this study was to examine the association of sociodemographic and biological characteristics, behavioural patterns, and school-related and sport-specific variables with time spent participating in sport.MethodsA total of 1837 secondary school students (age: 14.6 ± 1.2 years; 50.9 % boys) from 19 of 23 schools in the Otago Region (New Zealand) completed an online sport survey and Youth Physical Activity Questionnaire in 2009. Using multilevel modeling, we examined the association of individual-, school- and sport-related variables on sport participation and the amount of time spent in sports.ResultsHigher rates of sport participation were associated with lower neighbourhood deprivation scores (OR (95%CI): 0.75 (0.49-1.14), 0.57 (0.38-0.86), 0.48 (0.28-0.81)), higher quintiles of physical activity (2.89 (2.10-3.96), 2.81 (1.68-4.70), 3.54 (2.24-5.57), 3.97 (1.99-7.95)), highest quintiles of screen time (1.58 (0.94-2.65), 1.99 (1.42-2.80), 2.17 (1.43-3.30), 1.88 (1.37-2.57)) and boys only school status (2.21 (1.57-3.10)). Greater amount of time spent in sports was associated with male gender (0.56 (0.43-0.74), lower neighbourhood deprivation scores (0.72 (0.59-0.93), 0.78 (0.58-1.04), 0.62 (0.39-1.00)), higher quintiles of physical activity (3.18 (2.29-4.41), 4.25 (2.91-6.20), 8.33 (5.58-12.44), 6.58 (4.07-10.64)), highest quintile of screen time (1.83 (1.31-2.56), greater availability of sports outside school (1.68 (1.22-2.32)), better sport management (2.57 (1.63-4.07)) and provision of sport courts at school (0.57 (0.40-0.81)). Conversely, obesity was associated with less time spent participating in sport (0.50 (0.31-0.80)).ConclusionResults support the use of sport participation as an effective strategy to increase physical activity levels and identify target groups and areas for interventions, program design and policy development. Interventions should focus on improving accessibility to sport programs for all adolescents, providing adequate sport grounds at school, and promoting good sport management practices. Programs and policies encouraging sport participation should address in particular the needs of adolescents living in deprived neighborhoods, those attending coeducational and girls-only schools, and those who are obese.

Assessment of physical activity needs to improve in order to gain a more comprehensive understanding of the relationship between characteristics of the environment and physical activity. Our study evaluated a method [Block Walk Method (BWM)] for observing physical activity along residential sidewalks and streets. The BWM was utilized in 12 U.S. Census block groups over a three-month period. Examination transportation routes (ETRs), 1,524 m in length, were constructed and examined in each block group. On 6 days, ETRs were traversed by a trained observer for 50 min. Physical activities, street names, and geographical locations (e.g., addresses) were recorded. We found encouraging results for the BWM. The level of agreement between independent observers was 998% for activity type. The number of individuals seen walking, running, or biking did not differ significantly between the days of the week or observation times. The number of individuals observed was correlated with block group characteristics (e.g., percent walking/biking to work) and weather (e.g., temperature). The BWM is an easy to use, economically viable observational approach to obtaining reliable information concerning physical activities performed on residential streets and sidewalks. Its use could help advance our understanding about the environment-physical activity relationship.