Karianne Backx

Effects of chronic bicarbonate ingestion on the performance of high-intensity work

Abstract We have evaluated whether sodium bicarbonate, taken chronically (0.5 g · kg−1 body mass) for a period of 5 days would improve the performance of eight subjects during 60 s of high-intensity exercise on an electrically braked cycle ergometer. The first test was performed prior to chronic supplementation (pre-ingestion) while the post-ingestion test took place 6 days later. A control test took place approximately 1 month after the cessation of all testing. Acid-base and metabolite data (n = 7) were measured from arterialised blood both pre- and post-exercise, as well as daily throughout the exercise period. The work completed by the subjects in the control and pre-ingestion test [21.1 (0.9) and 21.1 (0.9) MJ, respectively] was less than (P < 0.05) that completed in the post-ingestion test [24.1 (0.9) MJ; F(2,21) = 3.4, P < 0.05, power = 0.57]. Peak power was higher after the 5-day supplementation period (P < 0.05). Ingestion of the sodium bicarbonate for a period of 5 days resulted in an increase in pH (F(5,36) = 12.5, P < 0.0001, power = 1.0) over the 5-day period. The blood bicarbonate levels also rose during the trial (P < 0.05) from a resting level of 22.8 (0.4) to 28.4 (1.1) mmol · l−1 after 24 h of ingestion. In conclusion, the addition of sodium bicarbonate to a normal diet proved to be of ergogenic benefit in the performance of short-term, high-intensity work.

Low-intensity exercise exerts beneficial effects on plasma lipids via PPARF

INTRODUCTION An important mechanism by which physical activity reduces the risk of cardiovascular disease is through regulating plasma lipids. We investigated whether low-intensity exercise modulates lipid metabolism and the transcription factors peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor alpha (LXRalpha) responsible for controlling reverse cholesterol transport (RCT). METHODS Thirty-four sedentary adults, mean age 45.6 +/- 11.1 yr, participated in an 8-wk low-intensity exercise program consisting of walking 10,000 steps, three times a week. Subjects were randomly allocated to either an exercise group or a sedentary control group, and serum lipid or lipoprotein concentrations were determined. RESULTS Compared with controls, there was a significant decrease in total cholesterol (preexercise, 5.73 +/- 1.39 mmol x L; postexercise, 5.32 +/- 1.28 mmol x L) and a significant increase in HDL (preexercise, 1.46 +/- 0.47 mmol x L; postexercise, 1.56 +/- 0.50 mmol x L) after the exercise program. There was a significant increase in serum oxidized LDL (oxLDL) concentrations in the exercise group before and after exercise (0 wk, 554 +/- 107 ng x mL; 4 wk, 698 +/- 134 ng x mL; 8 wk, 588 +/- 145 ng x mL). A significant increase in leukocyte mRNA expression for PPARgamma (4 wk, 1.8 +/- 0.9-fold; 8 wk, 4.3 +/- 1.9-fold) was observed, which was reinforced by increased PPARgamma DNA-binding activity postexercise (preexercise, 0.22 +/- 0.09 OD units; postexercise, 1.13 +/- 0.29 OD units). A significant increase in gene expression was observed for the oxLDL scavenger receptor CD36 (4 wk, 3.8 +/- 0.6-fold; 8 wk, 2.7 +/- 0.5-fold) and LXRalpha (8 wk, 3.5 +/- 0.8-fold). Two LXRalpha-regulated genes involved in RCT, namely, ATP-binding cassette transporters A1 and GI (ABCA1 and ABCG1, respectively), were significantly up-regulated postexercise (8 wk: ABCA1, 3.46 +/- 0.56-fold; ABCG1, 3.06 +/- 0.47-fold). CONCLUSION We propose that the net effect of these changes may be to increase oxLDL uptake, to stimulate RCT, and thus to promote clearance of proatherogenic lipids from the vasculature, ultimately contributing to the cardiovascular benefits of low-intensity aerobic exercise.

Playground Designs to Increase Physical Activity Levels During School Recess A Systematic Review

School recess provides a major opportunity to increase children’s physical activity levels. Various studies have described strategies to increase levels of physical activity. The purpose of this systematic review is therefore to examine the interventions proposed as forms of increasing children’s physical activity levels during recess. A systematic search of seven databases was made from the July 1 to July 5, 2012, leading to a final set of eight studies (a total of 2,383 subjects—599 “preschoolers” and 1,784 “schoolchildren”) meeting the inclusion criteria. These studies were classified according to the intervention used: playground markings, game equipment, playground markings plus physical structures, and playground markings plus game equipment. The results of these studies indicate that the strategies analyzed do have the potential to increase physical activity levels during recess. The cumulative evidence was (a) that interventions based on playground markings, game equipment, or a combination of the two, do not seem to increase the physical activity of preschoolers and schoolchildren during recess and (ii) that interventions based on playground markings plus physical structures do increase the physical activity of schoolchildren during recess in the short to medium term.

A randomized feasibility study of a 12-week community-based exercise program for people with Huntington's Disease

Background and Purpose: The beneficial role of exercise as a treatment approach in Huntingtons disease (HD) has support from both preclinical work and small-scale studies; however, there have been no controlled studies of gym-based exercise in people with HD. This phase 2 randomized trial (ISRCTN 59910670) assessed feasibility, safety, acceptability, and benefit of a structured exercise program. Methods: Thirty-one participants (16 men; mean [SD] age = 50.4 [11.4] years) were randomly allocated to intervention (n = 16) or control group (usual care; n = 15). The intervention entailed a weekly supervised gym session of stationary cycling and resistance exercises, and a twice weekly independent home-based walking program. Retention and adherence rates and adverse events were recorded. Acceptability was determined from subjective reports of tolerability and physiological measures recorded during the gym sessions. Assessment of benefit included measures of physical abilities, disease severity, and quality of life (36-Item Short Form Health Survey). Analysis of covariance was used to test outcomes of interest. Results: The retention rate was 81% (9 of the 11 individuals who started the intervention completed it) and of the 9 who completed the program, 7 attended more than 75% (9/12) of the gym sessions. There were no related adverse events and the intervention was well tolerated by most participants. The between-group effect estimate for the Mental Component Summary score of the 36-Item Short Form Health Survey (n = 9; intervention, n = 13; control) was 7 (95% CI: 0.4–13.7) Moderate effect sizes for cognitive outcomes and measures of walking were also observed. Discussion and Conclusions: Observed effect sizes for clinical outcomes suggest the structured exercise program has benefit for persons with HD; larger scale trials are warranted. Video Abstract available (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A60) for more insights from the authors.

Cardiac output and related haemodynamics during pregnancy: a series of meta-analyses

Objective Cardiac output, a fundamental parameter of cardiovascular function, has consistently been shown to increase across healthy pregnancy; however, the time course and magnitude of adaptation remains equivocal within published literature. The aim of the present meta-analyses was to comprehensively describe the pattern of change in cardiac output during healthy pregnancy. Method A series of meta-analyses of previously published cardiac output data during healthy, singleton pregnancies was completed. PubMed and Scopus databases were searched for studies published between 1996 and 2014. Included studies reported absolute values during a predetermined gestational age (non-pregnant, late first trimester, early and late second trimester, early and late third trimester, early and late postpartum). Cardiac output was measured through echocardiography, impedance cardiography or inert gas rebreathing. Observational data were meta-analysed at each gestational age using a random-effects model. If reported, related haemodynamic variables were evaluated. Results In total, 39 studies were eligible for inclusion, with pooled sample sizes ranging from 259 to 748. Cardiac output increased during pregnancy reaching its peak in the early third trimester, 1.5 L/min (31%) above non-pregnant values. The observed results from this study indicated a non-linear rise to this point. In the early postpartum, cardiac output had returned to non-pregnant values. Conclusion The present results suggest that cardiac output peaks in the early third trimester, following a non-linear pattern of adaptation; however, this must be confirmed using longitudinal studies. The findings provide new insight into the normal progression of cardiac output during pregnancy.

Relación entre actividad física diaria, actividad física en el patio escolar, edad y sexo en escolares de educación primaria

BACKGROUND Sedentary behavior has negative effects on health. School recess playgrounds provide important settings and opportunities for children to engage in physical activity. The aim of this study was to describe the daily physical activity (PA) and physical activity during recess of Primary School children and the relationship with sex and age. METHOD 783 children (379 boys and 359 girls; age=8.5±1.7 years; range 6 to 11) participated in the study. Daily PA of each child was measured using a validated questionnaire that was completed by the parents of each child, whilst playground recess PA was measured using accelerometry. An ANOVA was used to determine differences by sex in each age group with confidence intervals and effect sizes. Also MANOVA was used to analyse the main and interaction effects of age and sex on variables. The Scheffe post-hoc test was used for comparisons. RESULTS Boys reported higher daily PA levels than girls across all age groups. The differences was bigger in seven (47,6±6,5 vs 42,6±6,4 MET/day; p<0,001), eight (48,5±8,6 vs 41,9±4,6MET/day; p<0,001) and nine years old (49,8±8,3 vs 44,1±5,9 MET/day; p<0,001). Measured recess PA was higher for boys compared to girls at age nine (28,4±12,0 vs 23.7±11,8 motion counts; p<0,039), ten (28,5±10,8 vs 23,7±10,0 motion counts; p<0,014) and eleven years old (24,6±12,2 vs 20,7±9,3 motion counts; p<0,047). CONCLUSION Daily PA is higher in boys compared to girls across all age groups (six to eleven years old). On the other hand, recess PA was higher only in boys between nine and eleven years.Background. Sedentary behavior has negative effects on health. School recess playgrounds provide important settings and opportunities for children to engage in physical activity. The aim of this study was to describe the daily physical activity (PA) and physical activity during recess of Primary School children and the relationship with sex and age. Method. 783 children (379 boys and 359 girls; age=8.5±1.7 years; range 6 to 11) participated in the study. Daily PA of each child was measured using a validated questionnaire that was completed by the parents of each child, whilst playground recess PA was measured using accelerometry. An ANOVA was used to determine differences by sex in each age group with confidence intervals and effect sizes. Also MANOVA was used to analyse the main and interaction effects of age and sex on variables. The Scheffe post-hoc test was used for comparisons. Results. Boys reported higher daily PA levels than girls across all age groups. The differences was bigger in seven (47,6±6,5 vs 42,6±6,4 MET/day; p<0,001), eight (48,5±8,6 vs 41,9±4,6MET/day; p<0,001) and nine years old (49,8±8,3 vs 44,1±5,9 MET/day; p<0,001). Measured recess PA was higher for boys compared to girls at age nine (28,4±12,0 vs 23.7±11,8 motion counts; p<0,039), ten (28,5±10,8 vs 23,7±10,0 motion counts; p<0,014) and eleven years old (24,6±12,2 vs 20,7±9,3 motion counts; p<0,047). Conclusion. Daily PA is higher in boys compared to girls across all age groups (six to eleven years old). On the other hand, recess PA was higher only in boys between nine and eleven years.

Exercise testing and training in people with Huntington’s disease

Objective: To explore exercise response in people with Huntington’s disease (HD). Design: Experimental observational study with a randomly allocated subgroup before/after interventional study. Setting: Community. Subjects: People with HD (n=30) and a healthy comparator group (n=20). Thirteen people from the HD group were randomly allocated to an exercise training program. Main measures: Heart rate (HR) and perceived exertion on the Borg-CR10 scale (RPE) during a submaximal cycle ergometer exercise test (three minute unloaded and nine minute 65%-75%HRmaximum phase). Expired air and lactate measures were available for 8 people with HD during the exercise. Intervention: A 12 week gym and home walking exercise programme (n=13). Results: People with HD achieved a lower work rate at nine minutes (82±42(0-195) v 107±35(50 -185) Watts (p<0.05)), but higher RPE at both three (3±2(0-7) v 1±1(0-4)) and nine minutes (7±3(1-10) v 5± 2(2-9)) both p<0.01, compared to the healthy group and did not achieve a steady state HR during unloaded cycling. People with HD also demonstrated higher than expected lactate at three 2.5±2.5(1.1-8)mmo.L-1 and nine 3.8±1.9(1.2-6.6)mmo.L-1 minutes and respiratory exchange ratio at three 0.78±0.03 (0.74-0.81) and nine minutes 0.94±0.11(0.81-1.15). After exercise training there were no changes observed in HR or RPE responses during the exercise test. Conclusions: There was a large variability in the observed metabolic and physiological responses to exercise in people with HD. The observed exercise responses suggest that altered exercise prescription parameters may be required for people with HD and that exercise response and factors’ affecting this requires further investigation.

High-intensity interval training versus moderate-intensity steady-state training in UK cardiac rehabilitation programmes (HIIT or MISS UK): study protocol for a multicentre randomised controlled trial and economic evaluation

Introduction Current international guidelines for cardiac rehabilitation (CR) advocate moderate-intensity exercise training (MISS, moderate-intensity steady state). This recommendation predates significant advances in medical therapy for coronary heart disease (CHD) and may not be the most appropriate strategy for the ‘modern’ patient with CHD. High-intensity interval training (HIIT) appears to be a safe and effective alternative, resulting in greater improvements in peak oxygen uptake (VO2 peak). To date, HIIT trials have predominantly been proof-of-concept studies in the laboratory setting and conducted outside the UK. The purpose of this multicentre randomised controlled trial is to compare the effects of HIIT and MISS training in patients with CHD attending UK CR programmes. Methods and analysis This pragmatic study will randomly allocate 510 patients with CHD to 8 weeks of twice weekly HIIT or MISS training at 3 centres in the UK. HIIT will consist of 10 high-intensity (85–90% peak power output (PPO)) and 10 low-intensity (20–25% PPO) intervals, each lasting 1 min. MISS training will follow usual care recommendations, adhering to currently accepted UK guidelines (ie, >20 min continuous exercise at 40–70% heart rate reserve). Outcome measures will be assessed at baseline, 8 weeks and 12 months. The primary outcome for the trial will be change in VO2 peak as determined by maximal cardiopulmonary exercise testing. Secondary measures will assess physiological, psychosocial and economic outcomes. Ethics and dissemination The study protocol V.1.0, dated 1 February 2016, was approved by the NHS Health Research Authority, East Midlands—Leicester South Research Ethics Committee (16/EM/0079). Recruitment will start in August 2016 and will be completed in June 2018. Results will be published in peer-reviewed journals, presented at national and international scientific meetings and are expected to inform future national guidelines for exercise training in UK CR. Trial registration number NCT02784873; pre-results.

The effect of a supported exercise programme in patients with newly diagnosed Type 2 diabetes: A pilot study

Abstract The aim of this study was to examine the effectiveness of either a standard care programme (n = 9) or a 12-week supported exercise programme (n = 10) on glycaemic control, β-cell responsiveness, insulin resistance, and lipid profiles in newly diagnosed Type 2 diabetes patients. The standard care programme consisted of advice to exercise at moderate to high intensity for 30 min five times a week; the supported exercise programme consisted of three 60-min supported plus two unsupported exercise sessions per week. Between-group analyses demonstrated a difference for changes in low-density lipoprotein cholesterol only (standard care programme 0.01 mmol · L−1, supported exercise programme –0.6 mmol · L−1; P = 0.04). Following the standard care programme, within-group analyses demonstrated a significant reduction in waist circumference, whereas following the supported exercise programme there were reductions in glycosylated haemoglobin (6.4 vs. 6.0%; P = 0.007), waist circumference (101.4 vs. 97.2 cm; P = 0.021), body mass (91.7 vs. 87.9 kg; P = 0.007), body mass index (30.0 vs. 28.7 kg · m−2; P = 0.006), total cholesterol (5.3 vs. 4.6 mmol · L−1; P = 0.046), low-density lipoprotein cholesterol (3.2 vs. 2.6 mmol · L−1; P = 0.028), fasting β-cell responsiveness (11.5 × 10−9 vs. 7.0 × 10−9 pmol · kg−1 · min−1; P = 0.009), and insulin resistance (3.0 vs. 2.1; P = 0.049). The supported exercise programme improved glycaemic control through enhanced β-cell function associated with decreased insulin resistance and improved lipid profile. This research highlights the need for research into unsupported and supported exercise programmes to establish more comprehensive lifestyle advice for Type 2 diabetes patients.

Relationship Between Break-Time Physical Activity, Age, and Sex in a Rural Primary Schools, Wales, UK

Abstract The aim of this study was to examine the physical activity during the break-times of primary school children in rural areas, and its relationship with age and sex. 380 children (192 boys and 188 girls; age=9.5±1.1 years) participated in the study. Break-time physical activity in the morning and lunch breaks was measured by accelerometry. An ANOVA was used to determine differences by sex in each age group, together with the respective confidence intervals and effect sizes. The results showed that 8-year-olds performed more physical exercise than 11-year-olds during the two breaks (p=0.005). For the boys, the 8-year-olds did more physical activity than the 10-year-olds, while, for the girls, those aged 8 and 9 years did more PA than girls aged 11 years (p<0.001). The only difference between boys and girls was for the 10-year-olds (p=0.043), with the boys doing more physical activity. Teachers might find it useful to take these findings into account to design physical activity programmes aimed at increasing the playground physical activity of older children.