No abstract

Identifying portable methods to measure body composition may be more advantageous than using body mass index (BMI) to categorize associated health consequences. Purpose: To compare the validity and reliability of a portable A-mode ultrasound (US) to a criterion three compartment model (3C) for the measurement of body composition. Methods: Forty-seven overweight and obese subjects participated in this study. Body composition was measured once via air displacement plethysmography for body density (Bd) and bioelectrical impedance spectroscopy for total body water (TBW) for the 3C calculations. Ultrasound measurements (BodyMetrix, Intelametrix) were made using an A mode, 2.5- MHz transmitter. All measurements were made on the right side of the body at 7 skinfold sites. The US software calculated percent body fat (%BF), fat mass (FM) and fat free mass (FFM) from the 7-site Jackson and Pollock equation. Results: %BF and FM, respectively, measured by the US (29.1±6.5%; 27.4±8.1 kg) was significantly lower compared to the 3C model (33.7±7.6%; 31.8±9.8 kg; p<0.0005). Fat free mass was significantly higher for the US (66.7±13.0 kg) compared to the 3C model (62.3±12.6; p = 0.001). The US demonstrated respectable reliability for %BF, FM, and FFM with intraclass correlation coefficients (ICC) ranging from 0.84–0.98 and standard error of the measurement (SEM) values and 2.2%BF, 1.9 kg, 1.9 kg, respectively. Discussion: The US was found to under predict %BF and FM with large deviations from the criterion (n = 10>4%BF error). While the US was not valid in this population, it was reliable producing results with minimal error, suggesting this technique may be effective for tracking changes in a weight loss or clinical setting.

Since the beginning of time people explored and developed new technologies to make their activities of daily living less labour intense, more efficient and, consequently, more sedentary. In addition, technological advances in medicine throughout history have led to a substantial increase in life expectancy. However, the combination of increased sedentary behaviour and increased life-expectancy resulted in a sharp increase in overweight and obesity related chronic conditions and illness. Although people may live longer, they are doing so with poorer physical function and a reduced quality of life. In this review we explore how technological advances have influenced people's sedentary behaviour and, through the lens of the affective-reflective theory (ART), we propose a means by which technology could be repurposed to encourage greater engagement in physical activity.

Rationale A primary goal of therapy for patients with peripheral arterial disease and intermittent claudication (PAD+IC) is increased ambulatory function. Supervised exercise rehabilitation was recently shown to confer superior walking benefits to pharmacological or surgical interventions. Increases in plasma inorganic nitrite, via oral nitrate, have been shown to increase exercise performance in both human and animal models, especially in hypoxic conditions. Objective To determine whether a 36-session exercise rehabilitation program while consuming oral inorganic nitrate (4.2mmol concentrated beetroot juice- EX+BR) would produce superior benefits over exercise plus placebo (EX+PL) in pain free walking and markers of increased skeletal muscle perfusion in patients with PAD+IC. Methods and Results This was a randomized, double-blind, per-protocol study design. Following the 12-week protocol claudication onset time (COT) on a maximal treadmill test increased by 59.2±57.3 sec for the EX+PL group (n=13), and by 180.3±46.6 sec for the EX+BR group (n=11) (p≤0.05). This produced a between treatment medium to large standardized effect size (Cohen’s d) of 0.62 (95%CI = −0.23 to +1.44). The data for six minute walk (6MW) distance showed a similar pattern with increases of 24.6±12.1 m and 53.3±19.6 m (p≤0.05) in the EX+PL and EX+BR groups respectively. Measures of gastrocnemius perfusion including ABI, peak reactive hyperemic blood flow and tissue deoxygenation characteristics during exercise (assessed my near infra-red spectroscopy) all changed significantly for the EX+BR group with moderate to large effect sizes over EX+PL changes. Conclusions While it is premature to speculate on overall clinical utility of a nitrate based therapy for PAD, this early pilot study evidence is encouraging. Specifically, our data suggests that increasing plasma nitrite prior to exercise may allow PAD subjects to train with less pain, at higher workloads for longer durations at each training session thereby maximizing the beneficial peripheral vascular and skeletal muscle adaptations. Clinical Trial Registration (NCT01684930, NCT01785524).