Precision of the GE Lunar Total Body-Less Head Scan for the Measurement of Three-Compartment Body Composition in Athletes.

INTRODUCTION: Dual energy X-ray absorptiometry (DXA) is widely used for the assessment of lean mass (LM), fat mass (FM) and bone mineral content (BMC). When observing standardised protocols, DXA has a high level of precision for the assessment of total body composition, including the head region. However, including the head region may have limited relevance in athletes and can be problematic when positioning taller athletes who exceed scan boundaries. This study investigated the precision of a new total-body-less-head (TBLH) DXA scan for three-compartment body composition measurement in athletes, with outcomes compared to the standard total-body DXA scan. METHODS: Precision errors were calculated from two consecutive scans with re-positioning (Lunar iDXA, GE Healthcare, Madison, WI), in male and female athletes from a range of sports. TBLH precision was determined from repeat scans in 95 athletes (male n = 55; female n = 40; age: 26.0 ± 8.5 y; body mass: 81.2 ± 20.5 kg; stature: 1.77 ± 0.11 m), and standard total-body scan precision was derived from a sub-sample of 58 athletes (male n = 19; female n = 39; age: 27.6 ± 9.9 y; body mass: 69.6 ± 14.8 kg; stature: 1.72 ± 0.94 m). Data from the sub-sample were also used to compare precision error and 3-compartment body composition outcomes between the standard total-body scan and the TBLH scan. RESULTS: TBLH precision errors [root mean squared-standard deviation, RMS-SD (coefficient of variation, %CV)] were bone mineral content (BMC): 15.6 g (0.5%), lean mass (LM): 254.3 g (0.4%) and fat mass (FM): 199.4 g (1.3%). These outcomes compared favourably to the precision errors derived from the standard total-body scan [BMC: 12.4 g (0.4%), LM: 202.2 g (0.4%), and FM: 160.8 g (1.1%)]. The TBLH scan resulted in lower BMC (-19.5%), LM (-6.6%), and FM (-4.5%) compared to the total-body scan (BMC: 2,308 vs. 2,865 g; LM: 46,954 vs. 50,276 g; FM: 15,183 vs. 15,888 g, all p<0.005). ConclusionThe TBLH scan demonstrates high in-vivo precision comparable to that of the standard total-body scan in a heterogeneous cohort of athletes. Given the impact of head exclusion on total body composition outcomes, TBLH scans should not be used interchangeably with the standard total-body scan.

Agreement between paper and pen visual analogue scales and a wristwatch-based electronic appetite rating system (PRO-Diary©), for continuous monitoring of free-living subjective appetite sensations in 7-10 year old children.

Electronic capture of free-living subjective appetite data can provide a more reliable alternative to traditional pen and paper visual analogue scales (P&P VAS), whilst reducing researcher workload. Consequently, the aim of this study was to explore the agreement between P&P VAS and a wristwatch-based electronic appetite rating system known as the PRO-Diary© technique, for monitoring free-living appetite sensations in 7-10 year old children. On one occasion, using a within-subject design, the 12 children (n=6 boys; n=6 girls) recorded their subjective appetite (hunger, prospective food consumption, and fullness), at two time points before lunch (11:30 and 12:00) and every 60 min thereafter until 21:00. The agreement between the P&P VAS and PRO-Diary© technique was explored using 95% limits of agreement and 95% confidence intervals (95% CI) calculated using the Bland and Altman (1986) technique. For hunger, prospective food consumption and fullness, the 95% limits of agreement were -1±25 mm (95% CI: lower limit -8mm; upper limit +6mm), 0±21 mm (95% CI: lower limit -6mm; upper limit +6mm) and -6±24 mm (95% CI: lower limit -14 mm; upper limit +1mm), respectively. Given the advantages associated with electronic data capture (inexpensive; integrated alarm; data easily downloaded), we conclude that the PRO-Diary© technique is an equivalent method to employ when continuously monitoring free-living appetite sensations in 7-10 year old children, but should not be used interchangeably with P&P VAS.

Agreement between two methods of dietary data collection in female adolescent netball players.

The accuracy of a combined dietary data collection method (self-reported, weighed food diary and 24-h recall technique) in 13 female, adolescent netball players (14-16 years) was explored. The girls were observed for a 12 h period (08:00-20:00), during which food and drink items were available ad libitum throughout the day and for the period between 20:00 and 08:00 the following morning. All items were covertly weighed before and after consumption to calculate observed energy intake. To calculate participant reported energy intake, food and drink items were weighed and recorded in a food diary by the participants, which was then supplemented with information from the 24-h recall the following morning. Agreement between observed and participant reported energy intake was calculated using the Bland and Altman technique. The mean difference between observed and participant reported energy intake was 0.46 MJ d(-1) (change in mean of 4.2%) indicating a slight bias towards over-reporting using the combined dietary data collection method. There was good agreement at the group level with the confidence interval for bias ranging from 0.00 to 0.92 MJ d(-1). The combined dietary data collection method is an effective technique to employ in 14-16-year old, female adolescent netball players when quantifying energy intake.

Energy intake and appetite following netball exercise over 5 days in trained 13-15 year old girls.

Free-living energy intake and subjective appetite were monitored in a group of eleven 13-15-year old trained adolescent netball players. During preliminary visits, a FLEX heart rate calibration and resting metabolic test were conducted. Heart rate data were collected during a netball exercise session and sedentary period and during the waking hours of all study days, to enable exercise-induced and 24-h energy expenditure to be quantified. The girls completed two 5-day treatment weeks, interspersed with a 2-week 'wash out' period. A 47-min bout of netball exercise or an equivalent sedentary period was carried out on day 3 of each treatment week. Energy intake was measured over each 5-day period using a combined self-reported, weighed, food diary and 24-h recall interview technique. Subjective appetite (hunger, prospective food consumption, fullness) and mood were rated by subjects immediately before and after meals each day, and before and after the netball exercise and the sedentary period. Forty eight hour energy intake was significantly higher following the netball exercise compared to the sedentary period. The girls felt significantly more hungry immediately following the netball exercise compared to immediately before. In conclusion, a single intermittent exercise bout alters subsequent appetite and energy intake in trained 13-15-year old girls.

Where next for the design, delivery, and evaluation of community-based physical activity prescription? Emerging lessons from the United Kingdom.

Despite widespread use, community-based physical activity prescription is controversial. Data limitations have resulted in a lack of clarity about what works, under what circumstances, and for whom, reflected in conservative policy recommendations. In this commentary we challenge a predominantly negative discourse, using contemporary research to highlight promising findings and "lessons learnt" for design, delivery, and evaluation. In doing so, we argue for the importance of a more nuanced approach to future commissioning and evaluation. Novelty: Amalgamating learning from multiple research teams to create recommendations for advancing physical activity prescription.