Aerobic Energy Expenditure Comparisons Between One Traditional and CrossFit-Based Exercise Session

This study sought to compare aerobic energy expenditure, recovery VO2, peak heart rate, and peak VO2 achieved across 45 min of exercise and 15 min of recovery performing both traditional and CrossFit®-based exercise. Thirty healthy, physically active participants of both genders (15 men, 15 women) performed a workout following the guidelines of the American College of Sports Medicine (traditional) and a workout following the CrossFit® method. Each workout consisted of a 5 min warm-up (light aerobic exercise and stretching), resistance exercise (both focused on leg exercises), cardiorespiratory exercise (a treadmill run for the traditional exercise and circuit training for the CrossFit®-based exercise) and 5 min cool-down (walking). The cool-down was followed by 10 min of sitting to record recovery values. During each workout the participants wore a K4b2 Cosmed unit to measure energy expenditure and VO2, and a Polar heart rate monitor to measure heart rate. Each measure was compared using a Dependent t-Test. Energy expenditure (468 ± 116 vs. 431 ± 96 kcal, p\u3c0.001), peak heart rate (189 ± 8 vs. 172 ± 8 bpm, p\u3c0.001), peak VO2 (3.22 ± 0.73 vs. 2.81 ± 0.63 L/min, p\u3c0.001) and average 15 min recovery VO2 (0.89 ± 0.24 vs. 0.78 ± 0.18 L/min, p\u3c0.001) were significantly greater in the CrossFit®-based workout. The present study suggests that CrossFit®-based exercise may result in greater aerobic energy expenditure than traditional exercise

Body Weight Support on Anti-Gravity Treadmill Induces Less Physiological Strain While Running

The anti-gravity treadmill developed by AlterG® can be used as an alternative to traditional treadmill running. The AlterG® unloads an individual’s body weight through lower body positive pressure (LBPP) and can support up to 80% of an individual’s body weight. The cardiorespiratory response resulting from a bout of exercise on an AlterG® treadmill may be attenuated compared to similar exercise on a traditional treadmill. PURPOSE: The purpose of this study was to compare the physiological responses of running at 0%, 15%, 30%, and 45% of body weight support (BWS) on the AlterG® to a traditional treadmill. METHODS: Ten healthy, active males (n = 3) and females (n = 7) (mean ± SD; age 23 ± 3 yrs, weight 60 ± 9.4 kg, height 167.6 ± 6.4 cm) completed two separate treadmill sessions in a randomized order. The exercise sessions included running on an AlterG® treadmill at 6 mph and 1% grade with 0%, 15%, 30% and 45% BWS for 8 min each. The other exercise session included running on a traditional treadmill (TT) at 6 mph and 1% grade for 8 min. Oxygen consumption (VO2) and respiratory exchange ratio (RER) were measured every minute through indirect calorimetry. Heart rate (HR) was measured every minute with a heart rate monitor and values were averaged during the last five minutes of each exercise trial. Rating of perceived exertion (RPE) was measured every other minute. Multivariate ANOVA was used for statistical analysis for each dependent variable (p \u3c 0.05). RESULTS: BWS at 15%, 30% and 45% on the AlterG® treadmill significantly reduced VO2 18.5%, 28.3 and 33.7% compared to TT and 0%. Additionally, HR with BWS at 15%, 30% and 45% was significantly reduced 8.9%, 13.1% and 17.9% compared to TT and 0%. RER during 30% and 45% was significantly different (-8.6% and -7.4%) from TT. Perceived exertion during 45% BWS was significantly lower (10-20%) than all protocols. There was no significant difference in VO2 or HR reported between 30% and 45%. 0% BWS displayed no significant difference in VO2 or HR when compared to the traditional treadmill. CONCLUSION: Increasing the percentage of BWS while running on the AlterG® treadmill reduced VO2 and HR compared to TT and 0%. Greater levels of BWS (30% and 45%) resulted in lowered RER and perceived exertion (45% only). The AlterG® treadmill appears to lessen the physiological demands of running compared to a traditional treadmill

Adherence to colorectal cancer screening guidelines in Canada

<p>Abstract</p> <p>Background</p> <p>To identify correlates of adherence to colorectal cancer (CRC) screening guidelines in average-risk Canadians.</p> <p>Methods</p> <p>2003 Canadian Community Health Survey Cycle 2.1 respondents who were at least 50 years old, without past or present CRC and living in Ontario, Newfoundland, Saskatchewan, and British Columbia were included. Outcomes, defined according to current CRC screening guidelines, included adherence to: i) fecal occult blood test (FOBT) (in prior 2 years), ii) endoscopy (colonoscopy/sigmoidoscopy) (prior 10 years), and iii) adherence to CRC screening guidelines, defined as either (i) or (ii). Generalized estimating equations regression was employed to identify correlates of the study outcomes.</p> <p>Results</p> <p>Of the 17,498 respondents, 70% were non-adherent CRC screening to guidelines. Specifically, 85% and 79% were non-adherent to FOBT and endoscopy, respectively. Correlates for all outcomes were: having a regular physician (OR = (i) 2.68; (ii) 1.91; (iii) 2.39), getting a flu shot (OR = (i) 1.59; (ii) 1.51; (iii) 1.55), and having a chronic condition (OR = (i) 1.32; (ii) 1.48; (iii) 1.43). Greater physical activity, higher consumption of fruits and vegetables and smoking cessation were each associated with at least 1 outcome. Self-perceived stress was modestly associated with increased odds of adherence to endoscopy and to CRC screening guidelines (OR = (ii) 1.07; (iii) 1.06, respectively).</p> <p>Conclusion</p> <p>Healthy lifestyle behaviors and factors that motivate people to seek health care were associated with adherence, implying that invitations for CRC screening should come from sources that are independent of physicians, such as the government, in order to reduce disparities in CRC screening.</p

Les conséquences démographiques de l'implantation d'agriculteurs repliés d'Afrique du Nord dans le Sud-Ouest

Brisebois D. Les conséquences démographiques de l'implantation d'agriculteurs repliés d'Afrique du Nord dans le Sud-Ouest. In: Économie rurale. N°36, 1958. pp. 19-27

The Effect of Repeated 40 Meter Sprint Trials on Salivary Cortisol in Elite Youth Female Soccer Players

The outcome of an intense exercise session is a stress response, potentially resulting in an increase in circulating cortisol. The acute cortisol response due to intense exercise may vary when comparing elite youth athletes and may not be noticeable in athletic performance. PURPOSE: The purpose of this study was to compare salivary cortisol responses between older (17-19 yo) and younger (11-13 yo) elite female soccer players after repeated 40m sprint trials. METHODS: All participants (n=8) were current United States Soccer Federation Development Academy players. Participants were placed into young (n=4, mean ± SD; age 12 ± 0 yrs; weight 48.3 ± 10.0 kg) and older (n=4, mean ± SD; 17 ± 1 yrs; weight; 60.2 ± 7.1 kg), and completed 3 trials. The control day (CON) consisted of collection of 2ml saliva samples at 0, 30 and 60 min, while participants sat quietly. Sprint Day 1 (SD1) and Sprint Day 2 (SD2) consisted of collection of a baseline saliva sample prior to sprinting, followed by ten 40m sprints with 30 seconds rest between sprints. On SD1 and SD2, additional saliva samples were then collected, immediately, 15, 30, 45, and 60 min following the last sprint. Sprint time (ST) was also recorded for each 40m sprint. Salivary cortisol (SC) levels were determined through enzyme-linked immunosorbent assay (ELISA) with sensitivity range RESULTS: There was a significant overall interaction between age and treatment days (F(2,12) = 4.586, p=0.033). An increase from CON to SD1 in the young group SC AUC (65.69%) was followed by an increase from SD1 to SD2 (46.66%). The older group increased SC AUC from CON to SD1 (157.52%) but decreased from SD1 to SD2 (-25.28%). There was a significant interaction between age and SC AUC (F(1,6) = 11.521, p=0.015) from SD1 and SD2. Additionally, ST did not significantly change, on either day, from sprint 1 to 10 in either group (F(1,6) = 1.075, p=0.34). CONCLUSION: The salivary cortisol response appears to differ in these elite athletes. Based on SC, the stress response in the mature youth athletes appears to decline, where the younger youth athlete appears to have an increase in the stress response to repetitive intense exercise. The physiological responses may not be outwardly observable as athletic performance, as sprint time values did not differ between the groups

Acute Effects of Concurrent Exercise on Biomarkers of Angiogenesis and Cardioprotection in Sedentary Adults: Preliminary Findings

There is evidence that performing brief bouts of aerobic-type exercise before each set of resistance exercise (i.e., integrated concurrent exercise) leads to superior health and fitness outcomes than when the modalities are performed independently (i.e., serial concurrent exercise). This advantage may be due in part to an exaggeration of functional hyperemia leading to an augmented cardiovascular adaptive response. PURPOSE: To analyze circulating levels of an endothelial shear stress-induced biomarker (microRNA-126) and a biomarker of cardiovascular development (microRNA-222) before and after volume- and time-matched serial and integrated concurrent exercise sessions in young, healthy, sedentary adults. METHODS: One female and three male participants (age = 27.8 ± 6 yrs; height = 172.8 ± 4.6 cm; weight = 71.8 ± 17.6 kg; BMI = 23.9 ± 4.9 kg/m2; VO2max = 30.13 ± 4.92 ml/kg/min) who were healthy and had performed no more than 1 hr of structured physical activity per week over the previous year completed all procedures. Participants performed one-repetition maximum tests on the Leg Press, Leg Curl, and Leg Extension exercises, and also completed a maximal cycling test. At least one week after testing, participants performed one of two exercise patterns: 3 sets of 10 repetitions of each resistance exercise followed by 20 min of cycling (serial), or 2 min of cycling performed before each set of resistance exercise (integrated). At least three weeks after the first exercise session, the participants performed the other session. Blood was collected before each exercise session, immediately after each exercise session, and 1 and 3 hours after each exercise session. RNA was extracted from the frozen plasma samples and microRNAs were quantified using PCR analysis. Values were normalized to a spike-in control and adjusted for plasma volume shifts. Fold-change of target microRNAs from baseline were calculated. Data were analyzed using a two-way ANOVA with repeated measures. Significance was set at 0.05. RESULTS: MicroRNA-126 changed 0.24 vs. 1.70-fold immediately post-exercise, 0.23 vs 0.75-fold 1 hr post-exercise, and 0.26 vs. 1.29-fold 3 hr post-exercise following serial and integrated concurrent exercise, respectively. There was no time effect (p = 0.34), no exercise effect (p = 0.85), and no interaction effect (p = 0.58). MicroRNA-222 changed 0.20 vs. 3.07-fold immediately post-exercise, 0.21 vs 1.21-fold 1 hr post-exercise, and 0.22 vs. 2.09-fold 3 hr post-exercise following serial and integrated concurrent exercise, respectively. There was no time effect (p = 0.26), no exercise effect (p = 0.73), and no interaction effect (p = 0.41). CONCLUSION: Although not statistically significant, a more robust response from integrated concurrent exercise compared to serial concurrent exercise was observed. At this early stage, it is unclear if these results will persist with the addition of more participants

Causes of death in canadian forces members deployed to Afghanistan and implications on tactical combat casualty care provision.

BACKGROUND: As part of its contribution to the Global War on Terror and North Atlantic Treaty Organization\u27s International Security Assistance Force, the Canadian Forces deployed to Kandahar, Afghanistan, in 2006. We have studied the causes of deaths sustained by the Canadian Forces during the first 28 months of this mission. The purpose of this study was to identify potential areas for improving battlefield trauma care. METHODS: We analyzed autopsy reports of Canadian soldiers killed in Afghanistan between January 2006 and April 2008. Demographic characteristics, injury data, location of death within the chain of evacuation, and cause of death were determined. We also determined whether the death was potentially preventable using both explicit review and implicit review by a panel of trauma surgeons. RESULTS: During the study period, 73 Canadian Forces members died in Afghanistan. Their mean age was 29 (+/-7) years and 98% were male. The predominant mechanism of injury was explosive blast, resulting in 81% of overall deaths during the study period. Gunshot wounds and nonblast-related motor vehicle collisions were the second and third leading mechanisms of injury causing death. The mean Injury Severity Score was 57 (+/-24) for the 63 study patients analyzed. The most common cause of death was hemorrhage (38%), followed by neurologic injury (33%) and blast injuries (16%). Three deaths were deemed potentially preventable on explicit review, but implicit review only categorized two deaths as being potentially preventable. CONCLUSIONS: The majority of combat-related deaths occurred in the field (92%). Very few deaths were potentially preventable with current Tactical Combat Casualty interventions. Our panel review identified several interventions that are not currently part of Tactical Combat Casualty that may prevent future battlefield deaths. PMID: 2207199

In vitro mitochondrial and myogenic gene expression is influenced by formoterol in human myotubes

Abstract Background Exercise is an effective treatment for establishing and maintaining skeletal muscle health. The interconnected cascade of gene expression pathways related to myogenesis, mitochondrial homeostasis, and thyroid hormone metabolism are critical to skeletal muscle health. This in vitro study was conducted to investigate the effects of exercise mimetic (formoterol) stimulation on human skeletal muscle cell signaling during myogenesis, and to provide insight on potential targets for future studies exploring therapies for skeletal muscle atrophy. Human myoblasts were cultured and differentiated to evaluate the effects of exercise mimetic stimulation on gene expression during mid and late myogenesis. Results We characterized the expression of 24 genes related to myogenesis, mitochondrial biogenesis, thyroid hormone metabolism, and cellular homeostasis and found that 21 genes were altered in response to formoterol, thus affecting related skeletal muscle pathways. Additionally, formoterol stimulation resulted in a myogenic program that appears to favor prolonged myoblast proliferation and delayed myotube maturation. Robust, yet distinctive effects of exercise mimetic stimulation on gene expression during mid-myogenesis and at terminal differentiation occurred. For instance, MYF5 increased in D6 FORM compared to other groups (p < 0.001) while MYOD and MYOG both decreased expression in the FORM groups compared to CON (p < 0.01). Secondly, mitochondrial biogenesis genes were stimulated following formoterol administration, namely PGC-1α, PGC-1β, and TFAM (p < 0.05). Uniquely in our study, thyroid hormone metabolism related genes were differentially expressed. For instance, DIO2 and DIO3 were both stimulated following formoterol administration (p < 0.05). Conclusions The results of our study support the groundwork for establishing further experiments utilizing exercise signaling as a clinical treatment in models targeting dysfunctional skeletal muscle cell growth