Applied Physiology Nutrition and Metabolism

Published by NRC Research Press
Online ISSN: 1715-5320
Print ISSN: 1715-5312
Publications
DXA whole-body and CT regional image analysis at 3rd lumbar vertebra (L3).  
Regional DXA analysis of (A) fat mass (FM) and (B) fatfree mass (FFM) at the L3 region correlates with DXA analysis of whole-body FM and FFM (n = 50).  
CT-based muscle analysis at L3 was strongly related to appendicular skeletal muscle mass measured with DXA (n = 31). DXAbased low muscle levels [males <7.26 kg/m 2 ; females <5.45 kg/m 2 (10)] generated corresponding CT values [males <55.4 cm 2 /m 2 and females <38.9 cm 2 /m 2 ].  
Human body composition is important in numerous cancer research domains. Our objective was to evaluate clinically accessible methods to achieve practical and precise measures of body composition in cancer patients. Dual-energy X-ray absorptiometry (DXA)-based analysis of fat and fat-free mass was performed in 50 cancer patients and compared with bioelectrical impedance analysis (BIA) and with regional computed tomography (CT) images available in the patients' medical records. BIA overestimated or underestimated fat-free mass substantially compared with DXA as the method of reference (up to 9.3 kg difference). Significant changes in fat-free mass over time detected with DXA in a subset of 21 patients (+2.2 +/- 3.2%/100 days, p = 0.003), was beyond the limits of detection of BIA. Regional analysis of fat and fat-free tissue at the 3rd lumbar vertebra with either DXA or CT strongly predicted whole-body fat and fat-free mass (r = 0.86-0.94; p < 0.001). CT images provided detail on specific muscles, adipose tissues and organs, not provided by DXA or BIA. CT presents great practical significance due to the prevalence of these images in patient diagnosis and follow-up, thus marrying clinical accessibility with high precision to quantify specific tissues and to predict whole-body composition.
 
The prevalence of childhood overweight and obesity has been shown to differ among regions, including rural-urban regional differences within nations. This study obtained simultaneous accelerometry-derived physical activity, 24 h activity, and food records to clarify the potential contributing factors to rural-urban differences in childhood overweight and obesity in Japan. Sixth-grade children (n = 227, 11-12 years old) from two urban elementary schools in Kyoto and four rural elementary schools in Tohoku participated in the study. The children were instructed to wear a pedometer that included a uniaxial accelerometer and, assisted by their parents, keep minute-by-minute 24 h activity and food records. For 12 children, the total energy expenditure was measured by the doubly labeled water method that was used to correct the Lifecorder-predicted activity energy expenditure and physical activity level. The overweight and obesity prevalence was significantly higher in rural than in urban children. The number of steps per day, activity energy expenditure, physical activity level, and duration of walking to school were significantly lower in rural than in urban children. In contrast, the reported energy intake did not differ significantly between the regions. The physical activity and duration of the walk to school were significantly correlated with body mass index. Rural children had a higher prevalence of overweight and obesity, and this may be at least partly caused by lower physical activity, especially less time spent walking to school, than urban children.
 
Overview of study design. The order of interventions in weeks 2 and 3 was randomized and counterbalanced. 
Participant characteristics.
Comparison of the highest and lowest quartile of mean off-task verbal behaviour on change in d2 test performance from no activity days to FUNterval days. A greater negative change is desirable for total errors (E), errors of commission (E Comm ), and % errors (E%), while a greater positive change is desirable for 
Regression R values of average off-task behaviour as a predictor of d2 test performance.
Effects of FUNtervals on d2 test of attention outcomes. Comparison of FUNterval with no activity days in males and females on total number of items processed (A), errors of omission (B), errors of commission (C), and % errors (D). *, Significant ( p < 0.05) main effect of intervention. 
The amount of time allocated to physical activity in schools is declining. Time-efficient physical activity solutions that demonstrate their impact on academic achievement-related outcomes are needed to prioritize physical activity within the school curricula. "FUNtervals" are 4-min, high-intensity interval activities that use whole-body actions to complement a storyline. The purpose of this study was to (i) explore whether FUNtervals can improve selective attention, an executive function posited to be essential for learning and academic success; and (ii) examine whether this relationship is predicted by students' classroom off-task behaviour. Seven grade 3-5 classes (n = 88) were exposed to a single-group, repeated cross-over design where each student's selective attention was compared between no-activity and FUNtervals days. In week 1, students were familiarized with the d2 test of attention and FUNterval activities, and baseline off-task behaviour was observed. In both weeks 2 and 3 students completed the d2 test of attention following either a FUNterval break or a no-activity break. The order of these breaks was randomized and counterbalanced between weeks. Neither motor nor passive off-task behaviour predicted changes in selective attention following FUNtervals; however, a weak relationship was observed for verbal off-task behaviour and improvements in d2 test performance. More importantly, students made fewer errors during the d2 test following FUNtervals. In supporting the priority of physical activity inclusion within schools, FUNtervals, a time efficient and easily implemented physical activity break, can improve selective attention in 9- to 11-year olds.
 
Glucose infusion rate during a hyperinsulinemic-euglycemic (2 mUÁkg –1 Ámin –1 ) in rats fed water (placebo), caffeinated coffee, or decaffeinated coffee for 4 weeks in combination with a high-fat diet (60% kcal from fat). *, Significant differences (p < 0.05) between treatment groups at individual timepoints. Data represent means ± SE; n = 8 or 9 animals per treatment. Previously published data adapted from Shearer et al. (2007). Results show that decaffeinated coffee, but not caffeinated coffee, mitigates the effects of high-fat food on insulin sensitivity.  
Blood glucose concentrations of rats after a meal tolerance test with or without chlorogenic acid (CGA) (120 mgÁkg –1 ; n = 8 for each treatment). *, Significant difference (p < 0.05) between treatment groups at individual timepoints. Data represent means ± SE. Significant difference (p < 0.05) also exists for area under the curve for CGA and placebo. Adapted from Tunnicliffe et al. (2008a). These results confirm that CGA may limit T2D by inhibiting intestinal glucose absorption or reducing liver glucose production following a meal.  
Antioxidant intake.
Schematic of CGA actions on the liver and gut. CGA is a potent antioxidant and inhibitor of hepatic glucose-6-phosphate translocase (G-6-Pase), the enzyme that catalyzes the terminal reaction of glycogenolysis and gluconeogenesis. Specifically, CGA and its derived compounds inhibit the transporting component (T1), resulting in concentration-dependent declines in net hepatic glucose output in vitro. In addition, CGA is known to alter incretin secretion and glucose absorption in the gut. GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide-1; T2D, type 2 diabetes.  
Epidemiological studies show coffee consumption to be correlated to large risk reductions in the prevalence of type 2 diabetes (T2D). Such correlations are seen with decaffeinated and caffeinated coffee, and occur regardless of gender, method of brewing, or geography. They also exist despite clear evidence showing that caffeine causes acute postprandial hyperglycemia and lower whole-body insulin sensitivity. As the beneficial effects of coffee consumption exist for both decaffeinated and caffeinated coffee, a component of coffee other than caffeine must be responsible. This review examines the specific coffee compounds responsible for coffee's effects on T2D, and their potential physiological mechanisms of action. Being plant-derived, coffee contains many beneficial compounds found in fruits and vegetables, including antioxidants. In fact, coffee is the largest source of dietary antioxidants in industrialized nations. When green coffee is roasted at high temperatures, Maillard reactions create a number of unique compounds. Roasting causes a portion of the antioxidant, chlorogenic acid, to be transformed into quinides, compounds known to alter blood glucose levels. Coffee consumption may also mediate levels of gut peptides (glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1), hormones intimately involved in the regulation of satiety and insulin secretion. Finally, coffee may have prebiotic-like properties, altering gut flora and ultimately digestion. In summary, it is evident that a better understanding of the role of coffee in the development and prevention of T2D has the potential to uncover novel therapeutic targets and nutraceutical formulations for the disease.
 
Loss of body weight and fat-free mass (FFM) are commonly noted with prolonged exposure to hypobaric hypoxia. Recent evidence suggests protein supplementation, specifically leucine, may potentially attenuate loss of FFM in subcaloric conditions during normoxia. The purpose of this study was to determine if leucine supplementation would prevent the loss of FFM in subcaloric conditions during prolonged hypoxia. Eighteen physically active male (n = 10) and female (n = 8) trekkers completed a 13-day trek in Nepal to Everest Base Camp with a mean altitude of 4140 m (range 2810-5364 m). In this double-blind study, participants were randomized to ingest either leucine (LEU) (7 g leucine, 93 kcal, 14.5 g whey-based protein) or an isocaloric isonitrogenous control (CON) (0.3 g LEU, 93 kcal, 11.3 g collagen protein) twice daily prior to meals. Body weight, body composition, and circumferences of bicep, thigh, and calf were measured pre- and post-trek. There was a significant time effect for body weight (-2.2% ± 1.7%), FFM (-1.7% ± 1.5%), fat mass (-4.0% ± 6.9%), and circumferences (p < 0.05). However, there was no treatment effect on body weight (CON -2.3 ± 2.0%; LEU -2.2 ± 1.5%), FFM (CON -2.1 ± 1.5%; LEU -1.2 ± 1.6%), fat mass (CON -2.9% ± 5.9%; LEU -5.4% ± 8.1%), or circumferences. Although a significant loss of body weight, FFM, and fat mass was noted in 13 days of high altitude exposure, FFM loss was not attenuated by leucine. Future studies are needed to determine if leucine attenuates loss of FFM with longer duration high altitude exposure.
 
The high prevalence of pediatric obesity has made preventing chronic diseases through healthy lifestyle behaviours a priority within pediatrics. Examining the association between diet and insulin sensitivity (IS) in youth may provide important insights for tailoring preventative dietary interventions. The objective of this study was to explore the associations among anthropometry, diet, and IS in 10- to 14-year-olds. In this cross-sectional study, the primary outcome measure was IS, measured noninvasively using a (13)C glucose breath test. Exposure variables included body mass index (BMI) z score and several dietary variables, including glycemic index (GI), glycemic load, and fiber, magnesium, vegetable and fruit, and fat intakes, all of which were derived from a validated, Web-based 24-h recall tool. Multiple regression analyses were performed for boys and girls separately. In total, 378 students (227 girls) aged 12.1 ± 1.2 years were studied. In this sample ∼24% of youth were considered overweight or obese (BMI z score = 0.41 ± 0.93). Multiple regression analyses showed that BMI z score was negatively and independently associated with (13)C insulin sensitivity score ((13)CISS) in both boys and girls (boys: β = -0.501; girls: β = -0.446; both p < 0.001). GI was negatively and independently related to (13)CISS in boys (β = -0.195, p < 0.05) but not in girls. Other dietary variables were not associated with IS. In addition to BMI z score, a low GI diet predicted (13)CISS in boys but not in girls. This finding suggests that interventions that reduce BMI (in both sexes) and include a low GI diet among boys may improve IS.
 
Illustration of the vibratory device strapped to the Achilles tendon 
Mean amplitudes of the Sol, GM and GL M max . 
In a previous study, Achilles tendon vibrations were enough to improve the triceps surae (TS) activation capacities and also to slightly increase TS Hoffmann reflex (H-reflex) obtained by summing up soleus (Sol) and gastrocnemii (GM and GL) EMGs. The purpose of the present study was to analyze separately Sol and GM or GL reflexes to account for different effects of the vibrations on the reflex excitability of the slow soleus and of the gastrocnemii muscles. A control group (n = 13) and a vibration group (n = 16) were tested in pre-test and post-test conditions. The Achilles tendon vibration program consisted of 1 h of daily vibration (frequency: 50 Hz) applied during 14 days. Maximal Sol, GM and GL H-reflexes, and M-waves were recorded, and their H(max)/M(max) ratios gave the index of reflex excitability. After the vibration protocol, only Sol H(max)/M(max) was enhanced (p < 0.001). The enhanced Sol reflex excitability after vibration is in favor of a decrease in the pre-synaptic inhibition due to the repeated vibrations and the high solicitation of the reflex pathway. Those results of a short period of vibration applied at rest may be limited to the soleus because of its high density in muscle spindles and slow motor units, both structures being very sensitive to vibrations.
 
The purpose of this study was to determine which performance measures of physical function are most closely related to frailty and whether physical function is different across levels of frailty. Fifty-three community-dwelling Greek women (63-100 years) participated in this study. Participants were divided into 3 tertiles based on level of frailty as calculated from a frailty index (FI): lowest FI group (<0.19 FI), intermediate FI group (0.19-0.36 FI), and highest FI group (>0.36 FI). Performance measures tested were handgrip and knee extension muscle strength and fatigue, upper and lower body muscular endurance, walking performance, agility, and dynamic balance. The greatest proportion of variance in the FI was explained by combining all performance-based measures of physical function. The performance measures that were most closely related to frailty yet different across levels of frailty were ambulatory mobility, lower body muscular endurance, and nondominant handgrip strength. Walking at a preferred pace had the strongest relationship to frailty rather than walking at maximal pace. Grip strength of the nondominant hand had a stronger correlation with frailty compared with the dominant hand. The FI was a better predictor of physical function than chronological age. The decline in physical function accelerated after the intermediate FI tertile. Definitions of frailty need to combine performance-based measures that can identify impairments in various domains of physical function. The assessment protocols of these measures are important.
 
Glucose uptake into skeletal muscle is primarily mediated by glucose transporter 4 (GLUT4). The number of GLUT4 polypeptides at the surface of muscle cells rises rapidly in response to insulin, contraction, depolarization, or energy deprivation. However, distinct mechanisms underlie the gain in surface GLUT4 in each case. Insulin promotes its exocytosis to the membrane, regulating vesicle movement, tethering, docking, and fusion. In contrast, muscle contraction, depolarization, and energy demand reduce GLUT4 endocytosis. The signals involved in each case also differ. Insulin utilizes Akt, Rabs, and selective actin remodelling, whereas depolarization and energy deprivation engage AMP-activated protein kinase and Ca2+-dependent signals. GLUT4 internalizes via 2 major routes that involve dynamin, but only one requires clathrin. The clathrin-independent route is slowed down by energy deprivation, and is regulated by AMP-activated protein kinase. In addition to regulation of the exocytic and endocytic movement of GLUT4, glucose uptake is also modulated through changes in the transporter's intrinsic activity. The glycolytic enzymes glyceraldehyde-3-dehydrogenase and hexokinase II contribute to such regulation, through differential binding to GLUT4.
 
Toll-like receptor (TLR) 2 and TLR4 signalling pathways activated by extracellular non-esterified fatty acids. AP1, activator protein 1; CD14, cluster of differentiation 14; IKK, I k B kinase; IRAK; interleukin-1 receptor-associated kinase; MAPK, mitogen-activated kinase; MD-2, myeloid differentiation-2; MYD88, myeloid differentiation primary response gene 88; NF k B, nuclear factor kappa B; TAK1, transforming growth factor beta-activated kinase 1; TIRAP, Toll–interleukin-1 receptor domain-containing adapter protein; TLR1, 6, Toll- like receptors 1 and 6; TRAF6, tumour necrosis factor receptor-associated factor 6. 
Toll-like receptors (TLRs) are transmembrane proteins that detect a variety of molecular components mostly derived from microorganisms. TLR2 and TLR4 are amongst others present in liver, adipose tissue, and skeletal muscle. Extracellular long-chain fatty acids bind TLR2 and 4 and induce downstream signalling cascades implicated in cellular stress and inflammatory processes. Evidence indicates that TLR activation by non-esterified fatty acids (NEFAs) may participate in the development of insulin resistance. Exercise seems to induce a downregulation of TLR expression in various tissues, a mechanism that may take part in the protective effect of exercise against insulin resistance. Moreover, TLRs seem to mediate the activation of mitogen-activated protein kinase p38 and Jun-amino-terminal kinase by extracellular NEFAs during endurance exercise. During this type of exercise, circulating NEFAs are known to regulate the expression of various genes including pyruvate dehydrogenase kinase 4, uncoupling protein 3, carnitine palmitoyltransferase 1, and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha. Whether these events are initiated by a TLR-dependent signal transduction remains to be investigated.
 
Insulin and exercise, the most important physiological stimuli to increase glucose transport in skeletal muscle, trigger a redistribution of GLUT4 glucose transporter proteins from the cell interior to the cell surface, thereby increasing glucose transport capacity. The most distal insulin signaling protein that has been linked to GLUT4 translocation, Akt substrate of 160 kDa (AS160), becomes phosphorylated in insulin-stimulated 3T3-L1 adipocytes; this is important for insulin-stimulated GLUT4 translocation and glucose transport. Insulin also induces a rapid and dose-dependent increase in AS160 phosphorylation in skeletal muscle. Available data from skeletal muscle support the concepts developed in adipocytes with regard to the role AS160 plays in the regulation of insulin-stimulated glucose transport. In vivo exercise, in vitro contractions, or in situ contractions can also stimulate AS160 phosphorylation. AMP-activated protein kinase (AMPK) is likely important for phosphorylating AS160 in response to exercise/contractile activity, whereas Akt2 appears to be important for insulin-stimulated AS160 phosphorylation in muscle. Evidence of a role for AS160 in exercise/contraction-stimulated glucose uptake is currently inconclusive. The distinct signaling pathways that are stimulated by insulin and exercise/contraction converge at AS160. Although AS160 phosphorylation is apparently important for insulin-stimulated GLUT4 translocation and glucose transport, it is uncertain whether elevated AS160 phosphorylation plays a similar role with exercise/contraction.
 
Relationship ( r ) of the log-transformed peak oxygen uptake ( V  ̇ O 2peak ) with ( a ) chronological and ( b ) skeletal age and with ( c ) log-transformed stature and ( d ) thigh volume. The 95% CIs of the correlation coefficients are also presented. 
Allometric modeling (eq. 2) and proportional multiplicative allometric modeling (eq. 3) of the peak oxygen uptake for body size variables and for body size variables and age, respectively.
Peak oxygen uptake (V̇O2peak) is routinely expressed in litres per minute and by unit of body mass (mL·kg(-1)·min(-1)) despite the theoretical and statistical limitations of using ratios. Allometric modeling is an effective approach for partitioning body-size effects in a performance variable. The current study examined the relationships among chronological age (CA), skeletal age (SA), total body and appendicular size descriptors, and V̇O2peak in male adolescent roller hockey players. Seventy-three Portuguese, highly trained male athletes (CA, 15.4 ± 0.6 years; SA, 16.4 ± 1.5 years; stature, 169.9 ± 6.9 cm; body mass, 63.7 ± 10.7 kg; thigh volume, 4.8 ± 1.0 L) performed an incremental maximal test on a motorized treadmill. Exponents for body size descriptors were 2.15 for stature (R(2) = 0.30, p < 0.01) and 0.55 for thigh volume (R(2) = 0.46, p < 0.01). The combination of stature or thigh volume and CA or SA, and CA(2) or SA(2), increased the explained variance in V̇O2peak (R(2) ranged from 0.30 to 0.55). The findings of the allometric model combining more than 1 body size descriptor (i.e., stature and thigh volume) in addition to SA and CA(2) were not significant. Results suggest that thigh volume and SA are the main contributors to interindividual variability in aerobic fitness.
 
Change in esophageal temperature ( T es , plotted every 30 s) 
(A) Laser Doppler perfusion measurements of fingertip skin blood flow during 10 min of baseline, 60 min of immersion, and 10 min of recovery. (At start of immersion, time = 0 min.) Data are averaged every 5 min and plotted as percent of baseline. (B) Change in fingertip skin temperature. Data are plotted every 30 s. *, Conditions have different rates of decrease from minute 0 to 30 ( p < 0.04). Not significant (NS) rates of cooling are similar for minutes 30 to 60. Error bars represent SD. Dotted lines indicate start and finish of immersion. Dashed line separates first and second 30-min periods of analysis. 
Head heat loss during the first and second 30-min periods of immersion. Error bars represent SD. *, Different from all other conditions ( p < 0.001) during both time periods. 
This study isolated the effects of dorsal, facial, and whole-head immersion in 17 degrees C water on peripheral vasoconstriction and the rate of body core cooling. Seven male subjects were studied in thermoneutral air (approximately 28 degrees C). On 3 separate days, they lay prone or supine on a bed with their heads inserted through the side of an adjustable immersion tank. Following 10 min of baseline measurements, the water level was raised such that the water immersed the dorsum, face, or whole head, with the immersion period lasting 60 min. During the first 30 min, the core (esophageal) cooling rate increased from dorsum (0.29 ± 0.2 degrees C h-1) to face (0.47 ± 0.1 degrees C h-1) to whole head (0.69 ± 0.2 degrees C h(-1)) (p < 0.001); cooling rates were similar during the final 30 min (mean, 0.16 ± 0.1 degrees C h(-1)). During the first 30 min, fingertip blood flow (laser Doppler flux as percent of baseline) decreased faster in whole-head immersion (114 ± 52% h(-1)) than in either facial (51 ± 47% h-1) or dorsal (41 ± 55% h(-1)) immersion (p < 0.03); rates of flow decrease were similar during minutes 30 to 60 (mean, 22.5 ± 19% h(-1)). Total head heat loss over 60 min was significantly different between whole-head (120.5 ± 13 kJ), facial (86.8 ± 17 kJ), and dorsal (46.0 ± 11 kJ) immersion (p < 0.001). The rate of core cooling, relative to head heat loss, was similar in all conditions (mean, 0.0037 ± 0.001 degree C kJ(-1)). Although the whole head elicited a higher rate of vasoconstriction, the face did not elicit more vasoconstriction than the dorsum. Rather, the progressive increase in core cooling from dorsal to facial to whole-head immersion simply correlates with increased heat loss.
 
Exercise is a potent stimulus for growth hormone (GH) release, although aging appears to attenuate this response. The aim of this study was to investigate GH responses to different exercise stimuli in young and early middle-aged men. Eight men aged 18-25 y and 8 men aged 40-50 y completed 3 trials, at least 7 days apart, in a random order: 30 s cycle-ergometer sprint (sprint), 30 min resistance exercise bout (resistance), 30 min cycle at 70% maximal oxygen consumption (endurance). Blood samples were taken pre-, during, and post-exercise, and area under the GH vs. time curve was calculated for a total of 120 min. Mean blood lactate concentrations and percentage heart rate maximum at which the participants were working were not different between groups in any of the trials. In both groups, blood lactate concentrations were significantly lower in the endurance trial than in the sprint and resistance trials. There were no significant differences in resting GH concentration between groups or trials. GH AUC was significantly greater in the young group than the early middle-aged group, in both sprint (531 (+/-347) vs. 81 (+/-54) microg.L-1 per 120 min, p = 0.003) and endurance trials (842 (+/-616) vs. 177 (+/-137) microg.L-1 per 120 min, p = 0.010). Endurance exercise elicits a greater GH response than sprint and resistance exercise; however, aging per se, factors associated with aging, or an inability to achieve a sufficient absolute exercise intensity results in a smaller GH response to an exercise stimulus in early middle-aged men.
 
In La Traversée Internationale du Lac St-Jean, held between 1955 and 2012 in Canada, the fastest women (r(2) = 0.61, p < 0.0001) and men (r(2) = 0.66, p < 0.0001) improved swimming speed over the years but the sex difference remained unchanged at 8.8% ± 5.6% (r(2) = 0.069, p = 0.065). Annually, for the 3 fastest swimmers, both women (r(2) = 0.53, p < 0.0001) and men (r(2) = 0.71, p < 0.0001) improved swimming speed between 1973 and 2012 and the sex difference decreased (r(2) = 0.29, p = 0.0016) from 14.4% ± 11.0% (1973) to 3.7% ± 1.4% (2012).
 
Provincial nutrition surveys of adults were conducted between 1990 and 1999 in Canada. Eight reports have been issued, and one is forthcoming. The purpose of this study was to estimate the national dietary intake of adult Canadians, using the publicly available data. Group mean-nutrient-intake data from 16 915 adults, aged 18 to 84 years, from published provincial reports were collated by age and sex for each of 9 provinces (Manitoba data were unavailable). Using Canadian census data appropriate to the year of collection, intake data were weighted to provide 1 national intake value for each nutrient, by 8 age and sex categories. In general, the energy and nutrient intake of adults decreased with age. For every age group, with the exception of vitamin C, intake of nutrients by men was greater than that by women. On the basis of a comparison of recently recommended intakes (Dietary Reference Intakes), the nutrients that are of concern because of inadequate intake include dietary fibre, calcium, magnesium, and folate. The data demonstrate the impact of folate fortification on folate intake; the mean intake became twice that of prefortification levels. This study used group mean-intake data; therefore, we cannot make definitive conclusions about the prevalence of inadequacy for the nutrients. Because of limitations with some provincial response rates, our data should not be construed as representative of the Canadian population. However, because these surveys were completed between the 19701972 Nutrition Canada Survey and the 2004 Canadian Community Health Survey, these population-weighted data might be a useful point of comparison for monitoring trends in nutrient intake from food.
 
. Additional analyses revealed that the odds of having MetS in men decreased in a linear dose-response manner when moving from the low to high 
Increasing physical activity is recommended as a therapeutic lifestyle change in the treatment of metabolic syndrome (MetS); however, little evidence exists for a relationship between cardiorespiratory fitness (CRF) and MetS in representative samples. Using data from the US National Health and Nutrition Examination Survey, 1999-2002, the relationship between CRF and MetS was examined in 692 men and 608 women between the ages of 18 and 49 y who were free of major disease and disability. In men, the odds of MetS were significantly lower in moderate and high CRF categories versus the low CRF category, whereas in women there were no significant relationships between CRF and MetS.
 
We investigated the possible association between the sterol regulatory element-binding protein-1c gene (SREBP-1c) rs2297508 polymorphism and the changes in lipid profiles in a high-carbohydrate and low-fat (high-CHO/LF) diet in a Chinese population well characterized by a lower incidence of coronary heart disease and a diet featuring higher carbohydrate and lower fat. Fifty-six healthy youth (aged 22.89 ± 1.80 years) were given wash-out diets of 31% fat and 54% carbohydrate for 7 days, followed by the high-CHO/LF diet of 15% fat and 70% carbohydrate for 6 days, without total energy restriction. Fasting blood samples were collected. Serum variables of lipid and glucose metabolism after the wash-out and high-CHO/LF diets, as well as the rs2297508 polymorphism, were analyzed. Compared with the male subjects on the wash-out diet, significantly elevated levels of high-density lipoprotein cholesterol (HDL-C) and decreased levels of apolipoprotein B-100 were observed in the male carriers of the C allele after the high-CHO/LF diet. In the female subjects, significantly increased triacylglycerol levels, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) were found in the GG genotype after the high-CHO/LF diet. These results suggest that the C allele of the rs2297508 polymorphism is associated with a retardation of the increases in serum triacylglycerol, serum insulin, and HOMA-IR in females and with the elevated serum HDL-C in males after the high-CHO/LF diet.
 
The effects of resistance exercise on fiber-type-specific expression of insulin-like growth factor I receptor (IGF-1R) and glucose transporter 4 (GLUT4) was determined in 6 healthy males. The expression of both genes increased in Type I fibers (p < 0.05), but only GLUT4 increased (p < 0.05) in Type II fibers. These data demonstrates that an acute bout of resistance exercise can up-regulate mechanisms of glucose uptake in slow and fast-twitch fibers, but the IGF signaling axis may not be as effective in fast-twitch fibers.
 
Endurance exercise promotes skeletal muscle adaptation, and exercise-induced peroxisome proliferator-activated receptor gamma coactivator-1alpha (Pgc-1alpha) gene expression may play a pivotal role in the adaptive processes. Recent applications of mouse genetic models and in vivo imaging in exercise studies have started to delineate the signaling-transcription pathways that are involved in the regulation of the Pgc-1alpha gene. These studies revealed the importance of p38 mitogen-activated protein kinase/activating transcription factor 2 and protein kinase D/histone deacetylase 5 signaling transcription axes in exercise-induced Pgc-1alpha transcription and metabolic adaptation in skeletal muscle. The signaling-transcription network that is responsible for exercise-induced skeletal muscle adaption remains to be fully elucidated.
 
The peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator 1alpha (PGC-1alpha), a nuclear encoded transcriptional coactivator, increases the expression of many genes in skeletal muscle, including those involved with fatty acid oxidation and oxidative phosphorylation. Exercise increases the expression of PGC-1alpha, and the exercise-induced upregulation of many genes is attributable, in part, to the preceding activation and upregulation of PGC-1alpha. Indeed, PGC-1alpha overexpression, like exercise training, increases exercise performance. PGC-1alpha reductions in humans have been observed in type 2 diabetes, while, in cell lines, PGC-1alpha mimics the exercise-induced improvement in insulin sensitivity. However, unexpectedly, in mammalian muscle, PGC-1alpha overexpression contributed to the development of diet-induced insulin resistance. This may have been related to the massive overexpression of PGC-1alpha, which induced the upregulation of the fatty acid transporter FAT/CD36 and led to an increase in intramuscular lipids, which interfere with insulin signalling. In contrast, when PGC-1alpha was overexpressed modestly, within physiological limits, mitochondrial fatty acid oxidation was increased, GLUT4 expression was upregulated, and insulin-stimulated glucose transport was increased. More recently, similar PGC-1alpha-induced improvements in the insulin-resistant skeletal muscle of obese Zucker rats have been observed. These studies suggest that massive PGC-1alpha overexpression, but not physiologic PGC-1alpha overexpression, induces deleterious metabolic effects, and that exercise-induced improvements in insulin sensitivity are induced, in part, by the exercise-induced upregulation of PGC-1alpha.
 
Urinary oxidative (8-OHDG, 5-OHMU) and plasma antioxidant capacity markers (FRAP). 
Blood natural killer cells over time in blueberry (N = 12) and control groups (N = 11). Main effects were treatment (p = 0.003), time (p ≤ 0.001), and interaction (p = 0.047). Since interaction was significant, point to point comparisons were examined after a Bonferroni correction to p ≤ 0.025. **, Significantly different from corresponding control value (p ≤ 0.01); ***, significantly different from corresponding control value (p ≤ 0.001). Values are means ± SD. 
Blueberries are rich in antioxidants known as anthocyanins, which may exhibit significant health benefits. Strenous exercise is known to acutely generate oxidative stress and an inflammatory state, and serves as an on-demand model to test antioxidant and anti-inflammatory compounds. The purpose of this study was to examine whether 250 g of blueberries per day for 6 weeks and 375 g given 1 h prior to 2.5 h of running at ∼72% maximal oxygen consumption counters oxidative stress, inflammation, and immune changes. Twenty-five well-trained subjects were recruited and randomized into blueberry (BB) (N = 13) or control (CON) (N = 12) groups. Blood, muscle, and urine samples were obtained pre-exercise and immediately postexercise, and blood and urine 1 h postexercise. Blood was examined for F₂-isoprostanes for oxidative stress, cortisol, cytokines, homocysteine, leukocytes, T-cell function, natural killer (NK), and lymphocyte cell counts for inflammation and immune system activation, and ferric reducing ability of plasma for antioxidant capacity. Muscle biopsies were examined for glycogen and NFkB expression to evaluate stress and inflammation. Urine was tested for modification of DNA (8-OHDG) and RNA (5-OHMU) as markers of nucleic acid oxidation. A 2 (treatment) × 3 (time) repeated measures ANOVA was used for statistical analysis. Increases in F₂-isoprostanes and 5-OHMU were significantly less in BB and plasma IL-10 and NK cell counts were significantly greater in BB vs. CON. Changes in all other markers did not differ. This study indicates that daily blueberry consumption for 6 weeks increases NK cell counts, and acute ingestion reduces oxidative stress and increases anti-inflammatory cytokines.
 
Average (SD) of swimming speed (left panel), stroke length (middle panel), and stroke frequency (right panel) for the eight 25-m laps of a 200-m front crawl. a, Statistically
Average (SD) frequency (left panel) and amplitude (right panel) ratio between the last 25-m and the first 25-m lap values. FCR, flexor carpi radialis; BB, biceps brachii; TB, triceps brachii; PM, pectoralis major; UT, upper trapezius; TA, tibialis anterior; BF, biceps femoris; RF, rectus femoris; iEMG, integrated electromyography. *, p < 0.05. 
The aim of this study was to investigate how upper- and lower-limb muscle fatigue evolves in a 200-m front crawl swimming race. Surface electromyography signals were collected from the flexor carpi radialis, biceps brachii, triceps brachii, pectoralis major, upper trapezius, tibialis anterior, biceps femoris, and rectus femoris muscles of 10 international-level swimmers; 4 underwater cameras were used for kinematic analysis. In addition, blood lactate was measured before and after the test using capillary blood samples. Swimming speed and stroke length decreased from the beginning to the end of the effort, whereas stroke frequency increased after an initial decrease to maintain speed. Concomitant with the decrease in speed, blood lactate increased to 11.12 (1.65) mmol·L(-1). The changes in stroke parameters were associated with an increase in integrated electromyography (20%-25%) and a decrease in spectral parameters (40%-60%) for all of the upper-limb muscles, indicating the reaching of submaximal fatigue. The fatigue process did not occur regularly during the 8 laps of the 200 m but was specific for each muscle and each subject. Lower-limb muscles did not present signals of fatigue, confirming their lower contribution to swimming propulsion. The test was conducted to individualize the training process to each muscle and each subject.
 
This introduction summarizes the topics addressed in the three companion review papers on various issues surrounding exercise and the endothelium. Leading experts in the field discuss the most recent findings regarding the following: (i) nitric oxide and exercise hyperemia, (ii) the response of the endothelium to exercise training, and (iii) the impact of exercise on the vascular biology of angiotensin as it relates to the vascular endothelium.
 
This short introduction includes a brief description of papers that were prepared following the "Symposium on Exercise--Diet and Energy Balance", which was presented at the Canadian Society for Exercise Physiology annual meeting in the autumn of 2005. Briefly, these three papers discuss findings related to (i) the emerging role of exercise in the treatment of obesity and its co-morbidities, (ii) the role of novel proteins secreted by fat, and (iii) the control of appetite and food intake after successful weight loss.
 
Dr. Oded Bar-Or was a pioneer in the study of children's physical activity, exercise, and health. His diverse research interests led to numerous scientific explorations on thermoregulation, aerobic and anaerobic capacity, physical activity, economy of movement, obesity, neuromuscular diseases, asthma, cystic fibrosis (CF), and many more. To commemorate the extraordinary contributions that Dr. Bar-Or made to the study of exercise and youth, a symposium on pediatric exercise physiology was held at the CSEP's 2006 Annual Meeting in Halifax. The papers in the following pages include the four papers presented by international colleagues in his memory.
 
The increasing prevalence of obesity among the world's children and youth was the impetus for an international conference convened in Toronto, Canada, to examine issues related to physical activity and obesity in children (24-27 June 2007). The goal of the conference was to assimilate, interpret, and share scientific evidence with key stakeholders to develop recommendations concerning effective physical activity policies and programs to address obesity in children. The conference was attended by approximately 1,000 delegates from 33 countries who gathered to listen to the invited speakers and to share information on promising practices related to the promotion of physical activity with the aim of reducing the burden of obesity in children. The major topics addressed at the conference included the biological and behavioural causes of obesity, current and past levels of physical activity and sedentarism in children, the role of the social, family, and built environments in addressing the physical activity deficit, and the role of legislation and industry in promoting physical activity. Promising physical activity interventions among children were presented, and important research, policy, and practice recommendations to address the issue of physical inactivity and obesity were provided.
 
The number of observations obtained from each of the 14 players. 
Individual playing time and fluid loss for the players at club B throughout the Super League season, mean ± SD. 
The hydration status of rugby league players during competitive home match play was assessed throughout the 2008 Super League season. Fourteen players from 2 Super League clubs were monitored (72 observations). On arrival, 2 h prior to kick off, following normal prematch routines, players' body mass were measured following a urine void. Prematch fluid intake, urine output, and osmolality were assessed until kick off, with additional measurements at half time. Fluid intake was also monitored during match play for club B only, and final measurements of variables were made at the end of the match. Mean body mass loss per match was 1.28 ± 0.7 kg (club A, 1.15 kg; club B, 1.40 kg), which would equate to an average level of dehydration of 1.31% (mass loss, assumed to be water loss, expressed as a percentage of body mass), with considerable intra-individual coefficient of variation (CV, 47%). Mean fluid intake for club B was 0.64 ± 0.5 L during match play, while fluid loss was 2.0 ± 0.7 L, with considerable intra-individual CV (51% and 34%, respectively). Mean urine osmolality was 396 ± 252 mosm·kg-1 on arrival, 237 ± 177 mosm·kg-1 prematch, 315 ± 133 mosm·kg-1 at half time, and 489 ± 150 mosm·kg-1 postmatch. Body mass losses were primarily a consequence of body fluid losses not being completely balanced by fluid intake. Furthermore, these data show that there is large inter- and intra-individual variability of hydration across matches, highlighting the need for future assessment of individual relevance.
 
The effective promotion of healthy dietary patterns rests on a supportive policy environment. Given the vast, ever-expanding selection of foods in Canadian supermarkets and the proliferation of nutrition-related food marketing, more effective communication tools are needed to help consumers understand food selections within the context of a total diet. In addition, policy actions at the federal, provincial, and municipal levels are needed to lift economic and geographic barriers to food access for specific population subgroups.
 
This presentation explores the value of mechanical, electrical, and mathematical analogues in understanding and evaluating a variety of closely integrated transport processes in human biology. Particular attention is directed to a major interest of John Sutton: the factors limiting transport of oxygen from the atmosphere to the working muscles when exercising in a variety of hostile environments. In most circumstances, the limiting term in a closely linked chain of conductances seems to be in the blood stream, and its magnitude can be estimated by measurements of maximal oxygen intake. Despite recent criticisms of this index by those who have proposed a feed-forward control of maximal aerobic effort, conductance theory suggests that the main limitation of oxygen transport is normally maximal cardiac output. Therefore, careful laboratory determinations of maximal oxygen intake continue to provide a convenient integrating assessment of an individual's cardiorespiratory function, with many important applications in sports medicine and exercise science.
 
The purpose of this study was to determine consumers' perceptions of industrially produced trans fats. A cross-sectional study was conducted in Regina at 3 different grocery store chains located in 3 different regions. A 21-item survey was administered in English by 3 research assistants at the grocery stores over a 5-day period. Of 498 potential respondents who were approached, 211 completed the survey, for a 42% response rate. The majority of respondents were female and over 61 years of age. When respondents were asked if they looked for information on food packages while grocery shopping, none of the respondents indicated that they looked for trans fat on the food label. Ninety-six percent of respondents identified that trans fat is found in processed foods, whereas 42% of respondents incorrectly identified trans fat as being found in nonhydrogenated margarines. More female respondents self-reported that they had made dietary changes to decrease trans fat intake as compared with male respondents (p < 0.05). Those participants who made dietary changes to decrease trans fat intake had higher mean knowledge scores than did those who did not make changes (p < 0.043). Sixty-three percent of respondents indicated that they would not make dietary changes to their snack food selections even if their selections contained trans fat. Consumers know a little about trans fats and consider them to be a concern. However, consumers are reluctant to make dietary changes to limit these fats in their snack food selections.
 
The current study describes the frequency of use of different forms of nutrition marketing in Canada and the nutrients and conditions that are the focus of nutrition marketing messages. Prepackaged foods with a Nutrition Facts table (N = 10 487) were collected between March 2010 and April 2011 from outlets of the 3 largest grocery chains in Canada and 1 major western Canadian grocery retailer. The nutrition marketing information collected included nutrient content claims, disease risk reduction claims, and front-of-pack nutrition rating systems (FOPS). We found that nutrition marketing was present on 48.1% of Canadian food packages, with nutrient content claims being the most common information (45.5%), followed by FOPS on 18.9% of packages. Disease risk reduction claims were made least frequently (1.7%). The marketing messages used most often related to total fat and trans fat (15.6% and 15.5% of nutrient content claims, respectively). Limiting total and trans fats is a current public health priority, as recommended by Health Canada and the World Health Organization. However, other nutrients that are also recommended to be limited, including saturated fats, sodium, and added sugars, were not nearly as prominent on food labels. Thus, greater emphasis should be placed by the food industry on these other important nutrients. Repeated data collection in the coming years will allow us to track longitudinal changes in nutrition marketing messages over time as food marketing, public health, and consumer priorities evolve.
 
We reported results obtained in estimating the energy expenditure (EE) of an active adult subject participating in LANY Footrace 2011 (5129 km, 70 consecutive days). At each stage EE was calculated from literature metabolic cost equations and GPS-measured speeds-inclines. The subject's average speed was 7.41 ± 0.51 km·h(-1). Race expenditure amounted to 87% of EE (31.3 MJ·day(-1)) (47.8%-37.1% of measured maximal oxygen uptake). These results provide data about EE for future stage-type ultra-endurance competitors.
 
The present article summarizes the results from the Active Healthy Kids Canada 2012 Report Card on Physical Activity for Children and Youth. The Report Card assessed the physical activity levels of Canadian children and youth nationally, and the initiatives of public and nongovernment sectors to promote and facilitate physical activity opportunities for children and youth in Canada. Based on a comprehensive collection of data that were analyzed and/or published in 2011, 24 indicators relating to physical activity were graded. The Physical Activity Levels indicator, the core indicator of the Report Card, was graded an 'F' for the sixth consecutive year. Although the majority of grades remained unchanged from the previous year, four grades improved and two worsened. These results suggest that few Canadian children and youth have sufficient physical activity levels, and that greater efforts are required across sectors to promote and facilitate physical activity opportunities for children and youth in Canada.
 
The Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) are internationally known preparticipation screening tools developed on the basis of expert opinion. The primary purposes of this consensus document were to seek evidence-based support for the PAR-Q and PARmed-X forms, to identify whether further revisions of these instruments are warranted, to determine how people responding positively to questions on the PAR-Q can be safely cleared without medical referral, and to develop exercise clearance procedures appropriate for various clinical conditions across the human lifespan. Seven systematic reviews were conducted, examining physical-activity-related risks and effective risk-stratification procedures for various prevalent chronic conditions. An additional systematic review assessed the risks associated with exercise testing and training of the general population. Two gap areas were identified and evaluated systematically: the role of the qualified exercise professional and the requisite core competencies required by those working with various chronic conditions; and the risks associated with physical activity during pregnancy. The risks associated with being physically inactive are markedly higher than transient risks during and following an acute bout of exercise in both asymptomatic and symptomatic populations across the lifespan. Further refinements of the PAR-Q and the PARmed-X (including online versions of the forms) are required to address the unique limitations imposed by various chronic health conditions, and to allow the inclusion of individuals across their entire lifespan. A probing decision-tree process is proposed to assist in risk stratification and to reduce barriers to physical activity. Qualified exercise professionals will play an essential role in this revised physical activity clearance process.
 
The science of lipid research continues to rapidly evolve and change. New knowledge enhances our understanding and perspectives on the role of lipids in health and nutrition. However, new knowledge also challenges currently held opinions. The following are the proceedings of the 2013 Canadian Nutrition Society Conference on the Advances in Dietary Fats and Nutrition. Content experts presented state-of-the-art information regarding our understanding of fish oil and plant-based n-3 polyunsaturated fatty acids, nutrigenomics, pediatrics, regulatory affairs, and trans fats. These important contributions aim to provide clarity on the latest advances and opinions regarding the role of different types of fats in health.
 
The effects of daily exercise or caloric restriction on (A) FGF-21 serum concentration, (B) hepatic FGF-21 mRNA expression, and (C) hepatic FGF-21 protein content. Different letters above the bars indicate that the values (means ± standard error (SE); n = 6 – 8) are significantly different ( P < 0.05). AU, arbitrary units. 
Chronic treatment with fibroblast growth factor 21 (FGF-21) favorably improves obesity and nonalcoholic fatty liver disease (NAFLD) outcomes; however, FGF-21 expression is paradoxically elevated in obese conditions. Here, we sought to determine the effects of obesity prevention by daily exercise (EX) vs. caloric restriction (CR) on hepatic FGF-21 in the hyperphagic, Otsuka Long-Evans Tokushima Fatty (OLETF) rat. Four-week-old male OLETF rats were randomized into groups (n = 7-8 per group) of ad libitum fed, sedentary (OLETF-SED), voluntary wheel running exercise (OLETF-EX), or CR (OLETF-CR; 70% of SED) until 40 weeks of age. Nonhyperphagic, Long-Evans Tokushima Otsuka (LETO-SED) rats served as controls. Both daily EX and CR prevented obesity and NAFLD development observed in the OLETF-SED animals. This was associated with significantly (p < 0.01) lower serum FGF-21 (~80% lower) and hepatic FGF-21 mRNA expression (~65% lower) in the OLETF-EX and OLETF-CR rats compared with the OLETF-SED rats. However, hepatic FGF-21 protein content was reduced to the greatest extent in the OLETF-EX animals (50% of OLETF-SED) and did not differ between the OLETF-SED and OLETF-CR rats. Hepatic FGF-21 signaling mediators - hepatic FGF-21 receptor 2 (FGFR2, mRNA expression), hepatic FGF-21 receptor substrate 2 (FRS2, protein content), and co-receptor β-Klotho (protein content) - were all elevated (60%-100%, ~40%, and +30%-50%, respectively) in the OLETF-EX and OLETF-CR animals compared with the OLETF-SED animals. Daily exercise and caloric restriction modulate hepatic FGF-21 and its primary signaling mediators in the hyperphagic OLETF rat. Enhanced metabolic action of FGF-21 may partially explain the benefits of exercise and caloric restriction on NAFLD outcomes.
 
Custom-built modified boot apparatus designed to measure plantar-flexion torque. 
Summary of rates of recovery of voluntary and evoked properties during recovery in normothermic and hypothermic conditions
The purpose of this study was to investigate the effect of 22 degrees C local muscle temperature of intact human plantar flexors performing fatiguing contractions on evoked and voluntary contractile properties before and after fatigue. Twelve subjects were tested on plantar flexor voluntary torque, percent muscle activation derived from twitch interpolation, integrated electromyographic (iEMG) activity, and evoked torque and temporal characteristics of maximal twitch and tetanic stimulations before fatigue and 1, 5, and 10 min after intermittent, high-intensity, isometric fatigue under both normothermic and hypothermic conditions. Hypothermic and normothermic changes between time points were analysed by repeated-measures analysis of variance. Normothermic fatigue induced small to large effects (Cohen's d: 0.29-3.06) on voluntary and evoked contractile properties, whereas most effects of unfatigued hypothermia were limited to rate-dependent processes (Cohen's d: 0.78-1.70). Most tetanic properties were potentiated 1 min after normothermic fatigue, but remained unchanged by hypothermic fatigue, resulting in significant differences between the two conditions. Soleus iEMG significantly declined 1 min after normothermic fatigue (-29%), but not after hypothermic fatigue. Twitch torque was potentiated by 29% one minute after fatigue while normothermic, but was potentiated by 46% while hypothermic; rate of twitch torque development and time to peak twitch were potentiated by 39% and 10% while normothermic, but 89% and 28% while hypothermic. Although voluntary contractile properties are generally impaired soon after normothermic fatigue, most were not after hypothermic fatigue. Furthermore, evoked contractile properties were generally higher 1 min after hypothermic fatigue. We conclude that the hypothermic condition slows the recovery of potentiated evoked contractile properties back to baseline values.
 
Total oxygen consumption at each measurement point (A) and over 24 h (B). CON, control; HIIT, high-intensity interval training; END, continuous moderate-intensity training; HR max , maximal heart rate. *, p < 0.05 vs. CON; †, p < 0.05 vs. HIIT. 
Subjects performed high-intensity interval training (HIIT) and continuous moderate-intensity training (END) to evaluate 24-h oxygen consumption. Oxygen consumption during HIIT was lower versus END; however, total oxygen consumption over 24 h was similar. These data demonstrate that HIIT and END induce similar 24-h energy expenditure, which may explain the comparable changes in body composition reported despite lower total training volume and time commitment.
 
This 24 month study evaluated the effect of dietitian coaching combined with minimal endocrinologist follow up on the glycemic control and cardiovascular risks of diabetic participants, compared with conventional endocrinologist follow up. Participants with type 1 or type 2 diabetes were assigned to either the control group with conventional endocrinologist follow up (C; n = 50) or the dietitian-coached group (DC; n = 51) with on-site diabetes self-management education every 3 months combined with annual endocrinologist followup. Over the 24 month intervention, weight (-0.7 vs. +2.1 kg; p = 0.04), BMI (+0.3 vs. +0.7 kg/m(2); p = 0.009), and waist circumference (-1.3 vs. +2.4 cm; p = 0.01) significantly differed between the DC and control groups. HbA(1C) dropped significantly in participants of the DC versus the control group (-0.6% vs.-0.3%; p = 0.04). This was accompanied by improved overall energy intake (-548 vs. -74 kcal/day; p = 0.04). However, no link associated glycemic control to nutrient intake or intensiveness of pharmacotherapy. Coaching by a dietitian improves glycemic control and reduces certain cardiovascular risk factors in diabetic subjects, demonstrating that a joint dietitian-endocrinologist model of care provides a convenient strategy for cardiovascular risk management in the diabetic population.
 
Mean sleep period time estimates for each sleep identification method. 
Analysis of 24-h waist-worn accelerometer data for physical activity and sedentary behavior requires that sleep-period time (from sleep onset to the end of sleep, including all sleep epochs and wakefulness after onset) is first identified. To identify sleep-period time in children in this study, we evaluated the validity of a published automated algorithm that requires nonaccelerometer bed- and wake-time inputs, relative to a criterion expert visual analysis of minute-by-minute waist-worn accelerometer data, and validated a refined fully automated algorithm. Thirty grade 4 schoolchildren (50% girls) provided 24-h waist-worn accelerometry data. Expert visual inspection (criterion), a published algorithm (Algorithm 1), and 2 additional automated refinements (Algorithm 2, which draws on the instrument's inclinometer function, and Algorithm 3, which focuses on bedtime and wake time points) were applied to a standardized 24-h time block. Paired t tests were used to evaluate differences in mean sleep time (expert criterion minus algorithm estimate). Compared with the criterion, Algorithm 1 and Algorithm 2 significantly overestimated sleep time by 43 min and 90 min, respectively. Algorithm 3 produced the smallest mean difference (2 min), and was not significantly different from the criterion. Relative to expert visual inspection, our automated Algorithm 3 produced an estimate that was precise and within expected values for similarly aged children. This fully automated algorithm for 24-h waist-worn accelerometer data will facilitate the separation of sleep time from sedentary behavior and physical activity of all intensities during the remainder of the day.
 
Walker 256 tumor weight and cell proliferation. (A) Walker 256 tumor weight (g) 14 days after inoculation in sedentary (S) and anaerobic exercise trained (EX) rats. (B) Proliferation of Walker 256 tumor cells ex vivo (cpm) harvested from S and EX Walker 256 tumor-bearing rats. Cells were isolated from tumors and cultivated for 24 h in the presence of (2- 14 C)-thymidine. Data are presented as 
Lipid peroxidation, apoptosis, and necrosis. (A) Lipid peroxidation determined in the tumor tissue of S and EX Walker 256 tumor-bearing rats. (B) Percentage of apoptotic cells in tumors from S and EX Walker 256 tumor-bearing rats. (C) Percentage of necrotic cells in tumors from S and EX Walker 256 tumor-bearing rats. Data are presented as the mean ± SE of 18 tumors for each group. 
Bax and Bcl-2 expression determined by Western Blotting. (A) Bax expression in the tumor tissue from S and EX Walker 256 tumor-bearing rats. (B) Bcl-2 expression in the tumor tissue from S and EX Walker 256 tumor-bearing rats. Data are presented as the mean ± SE of 7 tumors for each group. 
Physical activity has been used in cancer prevention and treatment. In this study, we investigated some of the mechanisms by which anaerobic exercise reduces tumor growth. To do so, rats were trained for 8 weeks. Training consisted of jumping in a swimming pool for ten 30-s sets, with a load that was 50% of body weight attached to the back, 4 times per week. At the sixth week, anaerobic exercise trained rats (EX group) were inoculated with a suspension of Walker 256 tumor cells. Tumor weight, apoptotic tumor cells, tumor Bax and Bcl-2 protein expression, tumor lipid peroxidation, and tumor cell proliferation ex vivo were evaluated. Tumor weight was significantly lower in the EX group (∼30%) than in rats that did not undergo training (sedentary group) (p < 0.05). Apoptosis in the tumor cells of EX rats was 2-fold higher than in the tumor cells of sedentary rats; in addition, Bax expression increased by 10% and Bcl-2 decreased by 13% in EX rats. Lipid peroxidation was 4-fold higher in the tumor cells of EX rats than in those of sedentary rats (p < 0.05). Tumor cell proliferation ex vivo was 29% lower in the EX group than in the sedentary group (p < 0.05). In conclusion, Walker 256 tumor-bearing exercised rats presented more tumor cell apoptosis, a higher tumor content of lipid peroxides, pro-apoptotic protein expression balance, and reduced tumor weight and cell proliferation ex vivo, compared with sedentary rats. These events, together, account for the lower tumor growth we observed in the EX rats.
 
The primary purpose of this investigation was to examine the physiological profile of a National Hockey League (NHL) team over a period of 26 years. All measurements were made at a similar time of year (pre-season) in 703 male (mean age +/- SD = 24 +/- 4 y) hockey players. The data were analyzed across years, between positions (defensemen, forwards, and goaltenders), and between what were deemed successful and non-successful years using a combination of points acquired during the season and play-off success. Most anthropometric (height, mass, and BMI) and physiological parameters (absolute and relative VO2 peak, relative peak 5 s power output, abdominal endurance, and combined grip strength) showed a gradual increase over the 26 year period. Defensemen were taller and heavier, had higher absolute VO2 peak, and had greater combined grip strength than forwards and goaltenders. Forwards were younger and had higher values for relative VO2 peak. Goaltenders were shorter, had less body mass, a higher sum of skinfolds, lower VO2 peak, and better flexibility. The overall pre-season fitness profile was not related to team success. In conclusion, this study revealed that the fitness profile for a professional NHL ice-hockey team exhibited increases in player size and anaerobic and aerobic fitness parameters over a 26 year period that differed by position. However, this evolution of physiological profile did not necessarily translate into team success in this particular NHL franchise.
 
The nuclear factor (NF)-kB pathway. (1) NF-kB is normally inactive in the cytosol when it is bound to its inhibitor, IkB-a. (2) For NF-kB to become activated, the NF-kB pathway must be stimulated. Pathway stimulation results in IkB kinase (IKK) activation (phosphorylation), and IKK then phosphorylates IkB-a. (3) After IkB-a phosphorylation, IkB-a dissociates from the NF-kB p50/p65 subunits and is ubiquitinated and degraded by the 26S proteasome . (4) With the nuclear localization sequence (NLS) exposed, NF-kB translocates into the nucleus, binds to the promotor region of the NF-kB-regulated genes, and initiates the transcription of IkB-a and various anti-apoptotic and pro-inflammatory factors, including cytokines. (5) IkB-a binds to NF-kB and causes the release of NF-kB from the DNA. NF-kB/IkB-a, with a nuclear export sequence on IkB-a, exits the nucleus. Adapted from Ghosh and Karin (2002) and Karin and Lin (2002).  
(A) Effect of heat shock (HS) treatment on angiotensin (Ang) II-induced hypertension in rats. Heat shock treatment was administered 24 h before the initiation of Ang II infusion. Systolic blood pressure was measured on days 0, 1, 3, 5, 7, and 14 of Ang II infusion. Data points represent mean ± SEM (n = 6). *, p < 0.01, day 0 vs. day 1 to day 14 of Ang II infusion; p < 0.05, day 0 vs. day 1 of HS + Ang II infusion; p < 0.01, day 0 vs. day 3 to day 14 of HS + Ang II infusion; {, p < 0.01, day 3 to day 14 of Ang II infusion vs. HS + Ang II infusion. (B) Effect of HS treatment on Ang II-induced NF-kB activation in rat aorta. Semiquantitative densitometry of NF-kB activity. {, p < 0.01 vs. sham; §, p < 0.05; }, p < 0.01, Ang II infusion vs. HS + Ang II infusion. (From Chen et al. 2004a, used with permission of Cell Stress Chaperones, Vol. 9, pp. 101–102, # 2004 Cell Stress Society International.)  
Western analysis of IKK-a and IkB-a. Heat shock (HS) treatment depleted IKK-a and blocked the Ang II-induced phosphorylation of IKK-a (pIKK-a). HS treatment restored the Ang IIsuppressed expression of IkB-a, and HS suppressed the Ang IIinduced expression of phosphorylated IkB-a (pIkB-a). *, p < 0.01 vs. sham; {, p < 0.05 vs. sham; {, p < 0.01, HS + Ang II infusion vs. Ang II infusion; §, p < 0.01 vs. sham. }, p < 0.01, HS + Ang II infusion vs. Ang II infusion; **, p < 0.01 vs. sham; {{, p < 0.01, HS + Ang II infusion vs. Ang II; {{, p < 0.01 vs. sham. Data are means ± SE and are representative of 3 separate experiments. (From Chen et al. 2004b, used with permission of Am. J. Physiol. Heart Circ. Physiol., Vol. 287, p. H1109, # 2004 The American Physiological Society.)  
Western analysis of heat shock protein (Hsp)70 and Hsp27 in rat hearts after heat shock treatment and Ang II infusion. *, p < 0.01 vs. sham; {, p < 0.05 vs. sham. Data are means ± SE and are representative of 3 separate experiments. (From Chen et al. 2004b, used with permission of Am. J. Physiol. Heart Circ. Physiol., Vol. 287, p. H1110, # 2004 The American Physiological Society.)  
Heat shock proteins (HSPs) are critical for cell survival and have several mechanisms of action. HSPs regulate protein folding, suppress apoptosis, and regulate anti-oxidative activity. In addition, HSPs are involved in the regulation of the pro-inflammatory transcription factor nuclear factor (NF)-kappaB. When angiotensin (Ang) II is infused into rats, there is a significant increase in systolic blood pressure, and NF-kappaB is activated in the heart. If rats are heat shocked to induce the heat shock response and HSPs before Ang II infusion, there is a significant suppression of both the Ang II-induced increase in blood pressure and NF-kappaB activation in the heart. Although the role of specific HSPs in the regulation of NF-kappaB is unclear, several HSPs, including Hsp27 and Hsp70, are thought to be involved in the regulation of Ang II-induced NF-kappaB. The role of Hsp27 and Hsp70 in NF-kappaB activation is reviewed here, along with evidence suggesting that HSPs regulate Ang II-induced blood pressure through the regulation of NF-kappaB.
 
Elevated plasma lipoprotein (a) (Lp(a)) and total homocysteine (tHcy) concentrations, as well as fat distributions, are associated with cardiovascular disease (CVD) risk. The purpose of this study was to evaluate plasma Lp(a), tHcy, percentage body fat, anthropometric indices, and blood pressure (BP) and their relationships with each other in well-defined, hospital-based, CVD patients in a Nigerian African community. One hundred seventy patients suffering from hypertensive heart disease, hypertension, ischaemic heart disease, and myocardial infraction with the mean age of 45.3 +/- 1.3 years and 58 apparently healthy volunteers with the mean age of 44.8 +/-1.2 years were selected. Anthropometric indices and BP were measured. Percentage body fat, body mass index, and waist-to-hip ratio (WHR) were calculated. Plasma Lp(a) and tHcy concentrations were determined. The results showed significant increases in BP, skinfold thickness (SFT) variables, and WHR in all of the CVD patients. Plasma Lp(a) was also significantly increased (p < 0.001), whereas the slight increase in the mean tHcy was not statistically significant. Positive significant correlations were found between systolic BP, triceps, SFT, and percentage body fat (p < 0.01), whereas significant correlations were found between some body composition variables, tHcy, and systolic BP (p < 0.05). Our findings provide supportive evidence for altered plasma Lp(a) concentration in addition to some other traditional CVD risk factors in Nigerians. The role of homocysteine is not well defined.
 
Relationship between observed and predicted resting oxygen uptake ( V  ̇ O 2 ) from body surface area and percent body fat. The dashed lines represent the 95% limits of agreement of the best-fit 
Pearson's correlation coefficient between resting oxygen uptake (V ˙ O 2 ) and each predictor variable.
This study compared resting oxygen uptake (V̇O2) with the standard metabolic equivalent (MET) value of 3.5 mL·kg(-1)·min(-1), tested the accuracy of a previously published prediction model for resting V̇O2, and proposed a new prediction model for a more homogeneous population. One hundred and twenty-five apparently healthy men, aged 17-38 years, visited the laboratory for the assessment of resting V̇O2. The mean resting V̇O2 of 3.21 mL·kg(-1)·min(-1) (95% confidence interval (CI), 3.13 to 3.30) was significantly lower than the standard MET value of 3.5 mL·kg(-1)·min(-1) (mean difference, 0.29; 95% CI, 0.20 to 0.37; t = 6.7; p < 0.001). The prediction model proposed by a previous study, derived from a heterogeneous sample, exhibited no predictive ability in our more homogeneous sample. However, our population-specific regression model, which included body surface area and percent body fat as predictors, demonstrated relatively poor predictive ability, with a low R(2) (0.22) and high standard error of the estimate (0.42 mL·kg(-1)·min(-1)). Pearson's correlation coefficients for body surface area and resting V̇O2, and for percent body fat and resting V̇O2, were 0.20 (p = 0.022) and -0.36 (p < 0.001), respectively. In conclusion, the standard MET value of 3.5 mL·kg(-1)·min(-1) considerably overestimates mean resting V̇O2 in a relatively large group of apparently healthy men. Our population-specific prediction model for resting V̇O2 demonstrated relatively poor accuracy, although it was considerably more accurate than the previously published model. Further research needs to be conducted to establish accurate population-specific prediction models.
 
Top-cited authors
Jenna Gillen
  • University of Toronto
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  • Pennington Biomedical Research Center
Jonathan Peter Little
  • University of British Columbia - Okanagan
Mary E Jung
  • University of British Columbia - Vancouver
Emily Mire
  • Pennington Biomedical Research Center