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Despite intensive efforts to understand the extent to which skeletal muscle mitochondrial capacity changes in older humans, the answer to this important question remains unclear. To determine what the preponderance of evidence from in vivo studies suggests, we conducted a systematic review and meta-analysis of the effects of age on muscle oxidative capacity as measured noninvasively by magnetic resonance spectroscopy. A secondary aim was to examine potential moderators contributing to differences in results across studies, including muscle group, physical activity status, and sex. Candidate papers were identified from PubMed searches ( n = 3561 papers) and the reference lists of relevant papers. Standardized effects (Hedges' g) were calculated for age and each moderator using data from the 22 studies that met the inclusion criteria ( n = 28 effects). Effects were coded as positive when older (age, ≥55 years) adults had higher muscle oxidative capacity than younger (age, 20-45 years) adults. The overall effect of age on oxidative capacity was positive ( g = 0.171, p < 0.001), indicating modestly greater oxidative capacity in old. Notably, there was significant heterogeneity in this result ( Q = 245.8, p < 0.001; I2 = ∼70%-90%). Muscle group, physical activity, and sex were all significant moderators of oxidative capacity ( p ≤ 0.029). This analysis indicates that the current body of literature does not support a de facto decrease of in vivo muscle oxidative capacity in old age. The heterogeneity of study results and identification of significant moderators provide clarity regarding apparent discrepancies in the literature, and indicate the importance of accounting for these variables when examining purported age-related differences in muscle oxidative capacity. [ABSTRACT FROM AUTHOR]

The rates of overweight and obesity are rising in Canada and worldwide, and there is a need for effective methods for weight loss and weight maintenance to empower individuals to make changes. The purpose of this systematic review was to examine the evidence available for successful diet strategies for weight loss and weight maintenance among adults. A search was conducted of the following databases: CAB Abstracts, Central Register of Controlled Trials, EMBASE, MEDLINE, Food Science and Technology Abstracts, and Web of Knowledge. The studies investigated had participants who were overweight or obese and between 18 and 65 years of age. A successful study was defined as one that reported an intervention that created ≥5% weight loss from baseline and a maintenance phase during which the ≥5% weight loss was maintained from baseline to 12 months. After exclusions, the search resulted in 67 papers. Overall, for significant safe weight loss, an energy deficit was required, which was commonly achieved by reduced fat intake. Increased dietary fibre was also a component of 21% of successful interventions. Physical activity was included in 88% of successful interventions, and behaviour training such as self-monitoring was part of 92% of successful interventions. The same combination of energy and fat restriction, regular physical activity, and behavioural strategies was also required for successful weight maintenance. This review confirmed previous knowledge about weight loss and weight maintenance in adults. A comprehensive approach, including reduced dietary intake, regular physical activity, and behavioural strategies, is warranted and is supported by the research evidence. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to report the physical activity and health outcomes results from the Physical Activity Counselling (PAC) trial. Patients ( n = 120, mean age 47.3 ± 11.1 years, 69.2% female) who reported less than 150 min of physical activity per week were recruited from a large community-based Canadian primary care practice. After receiving brief physical activity counselling from their provider, they were randomized to receive 6 additional patient-centered counselling sessions over 3 months from a physical activity counsellor (intensive-counselling group; n = 61), or no further intervention (brief-counselling group; n = 59). Physical activity (self-reported and accelerometer) was measured every 6 weeks up to 25 weeks (12 weeks postintervention). Quality of life was also assessed, and physical and metabolic outcomes were evaluated in a randomly selected subset of patients (33%). In the intent-to-treat analyses of covariance, the intensive-counselling group self-reported significantly higher levels of physical activity at 6 weeks ( p = 0.009) and 13 weeks ( p = 0.01). There were no differences in self-reported physical activity between the groups after the intervention in the follow-up period, nor was there any increase in accelerometer-measured physical activity. Finally, the intensive-counselling patients showed greater decreases in percent body fat and total fat mass from 13 weeks to 25 weeks. Results for physical activity depended on the method used, with positive short-term results with self-report and no effects with the accelerometers. Between-group differences were found for body composition in that the intensive-counselling patients decreased more. A multisite randomized controlled trial with a longer intensive intervention and follow-up is warranted. [ABSTRACT FROM AUTHOR]