Bernard Gutin and Scott Owens
The purposes of this article were to (1): review recent studies of relations between physical activity and cardiometabolic biomarkers of youths (2); highlight areas in which additional research is needed; and (3) make recommendations for preventive interventions. Observational studies show that youths who engage in high amounts of moderate-vigorous physical activity display a more favorable cardiometabolic biomarker profile than youths who engage in lesser amounts of moderate-vigorous physical activity. Intervention studies in obese youths show that favorable changes in biomarkers are produced by moderate-vigorous physical activity doses of 150–180 min/week. However, for nonobese youths, intervention studies suggest that such doses are not effective; higher moderate-vigorous physical activity doses of approximately 300 min/week seem necessary. Continuing a physically active lifestyle from childhood into the adult years will enable people to maintain less end-organ damage and lower rates of morbidity and mortality from cardiovascular disease and type 2 diabetes.
Riley Galloway, Robert Booker and Scott Owens
Purpose: Current in-school physical activity (PA) policies lack regulation, which testifies to the urgency of monitoring in-school moderate to vigorous PA (MVPA). This study quantifies the demographical differences of in-school PA among elementary students. Methods: Fourth-grade students wore accelerometers during school for 1 week. The teachers logged information for PA setting and duration of opportunity. Results: The accelerometry data (N = 148) showed alarming results in the lack of MVPA during in-school PA opportunity times. Significant sex differences showed boys to accumulate more minutes MVPA per day in recess than girls (7.62 ± 5.87 and 5.19 ± 3.03, respectively). Racial differences showed that non-White students accumulated significantly more minutes of MVPA per week during the school day than White students (30.82 ± 19.09 and 23.44 ± 18.41, respectively). Conclusions: The students fell short of the recommended 30 min of MVPA per day during school hours, as advised by a state mandate. Significant differences were seen in PA levels across sex and race, supporting the need for enhanced attention to influential factors on PA engagement.
Andrew T. Scott, Thomas O’Leary, Simon Walker and Rachel Owen
To investigate the effect of ingesting a caffeinated carbohydrate gel (CC) 10 minutes prior on 2000-m rowing performance compared with a carbohydrate-only placebo gel (CP).
A counterbalanced, single-blind, crossover study design was employed (N = 13). All participants completed 1 familiarization trial followed by 2 experimental rowing time trials. The experimental trials were performed 10 min after ingesting CP (21.6 g of carbohydrate, 0 mg caffeine) or CC (21.6 g carbohydrate, 100 mg caffeine), and heart rate (HR), oxygen consumption (VO2), carbon dioxide production, minute ventilation (VE), respiratory-exchange ratio (RER), rating of perceived exertion (RPE), gastrointestinal discomfort (GI), and thirst perception (Thirst) were recorded every 200 m. Blood lactate [La−] was recorded immediately before and after exercise.
A paired-samples t test identified a significant improvement in 2000-m performance of 5.2 ± 3.9 s (1.1% ± 1.7%; P = .034). Two-way repeated-measures ANOVA revealed no significant treatment effect for HR (177 ± 8 vs 177 ± 9 beats/min, P = .817), VO2 (46.1 ± 6.5 vs 46.6 ± 6.2 mL · kg−1 · min−1, P = .590), VE (121.8 ± 14.7 vs 124.8 ± 15.7 L/min, P = .490), RPE, GI, or Thirst for CP and CC, respectively. Paired-samples t tests revealed no treatment effect for postexercise [La−] between CP and CC (11.72 ± 2.69 vs 12.26 ± 3.13 mmol/L, P = .534).
A relatively low dose of caffeine (1.3 ± 0.1 mg/kg body mass) in an isotonic carbohydrate gel ingested only 10 min before performance improved 2000-m rowing time by 5.2 ± 7.8 s (1.1% ± 1.7%).
Scott Owens, Laurel Lambert, Suzanne McDonough, Kenneth Green and Mark Loftin
This pilot study examined the feasibility of an interactive obesity prevention program delivered to a class of fourth-grade students utilizing daily e-mail messages sent to the students’ home computers. The study involved a single intact class of 22 students, 17 (77%) of whom submitted parental permission documentation and received e-mail messages each school day over the course of one month. Concerns regarding Internet safety and children’s use of e-mail were addressed fairly easily. Cost/benefit issues for the school did not seem prohibitive. Providing e-mail access to students without a home computer was accomplished by loaning them personal digital assistant (PDA) devices. In larger interventions, loaning PDAs is probably not feasible economically, although cell phones may be an acceptable alternative. It was concluded that this type of interactive obesity prevention program is feasible from most perspectives. Data from a larger scale effectiveness study is still needed.