Kate Woolf-May

Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men.

OBJECTIVE:To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness.DESIGN:Cross-sectional study of 113 nonsmoking men aged 30–45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (≥100 cm) subgroups.MEASUREMENTS:Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen.RESULTS:Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively.CONCLUSIONS:These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.

Metabolic equivalents during the 10-m shuttle walking test for post-myocardial infarction patients

Objective: Comorbidities are found to affect metabolic equivalents (METs). Therefore the main objective of this study was to compare METs (1 MET: oxygen uptake (Vo2) 3.5 ml/kg/min) during an incremental shuttle walking test (SWT) between non-cardiac and post-myocardial infarction (MI) men, and secondly to determine any differences in Vo2 (ml/kg/min) between flat treadmill walking and the turning during the shuttle walking in non-cardiac subjects. Design: Comparative study. Subjects: Thirty one post-MI (mean (SD) age 63.5 (6.5), range 53–77 years) from phase IV cardiac rehabilitation and 19 non-cardiac (64.6 (7.5), range 51–76 years) men participated. Methods: All subjects performed an SWT, and non-cardiac subjects a treadmill test of similar protocol. Throughout both, the subject’s Vo2 was measured. Results: Analysis comparing lines of regression showed METs at 1.12 to 4.16 mph were higher (p<0.001) for post-MIs versus non-cardiac subjects. For non-cardiac subjects, there were no differences between the treadmill test and SWT (p>0.9) and LoA showed acceptable agreement in METs between treadmill vs SWT, mean difference −1.1 (8.8) (1.96SD). Conclusion: It would appear that for asymptomatic individuals it is appropriate to apply established METs for flat walking to the SWT. However, the significantly higher METs for the post-MI compared with the non-cardiac subjects indicates the need for caution when using METs derived from healthy subjects in the prescription of exercise for myocardial patients.

Effects of an 18 week walking programme on cardiac function in previously sedentary or relatively inactive adults.

OBJECTIVE: To investigate the effects of an 18 week walking programme upon cardiac function. METHODS: 29 sedentary or relatively inactive but otherwise healthy subjects (15 walkers and 14 controls, aged 40-68 years) completed the study. The walkers completed a progressive 18 week walking programme which required an estimated average energy expenditure of 900 kcal week-1 for the total duration of the study and 1161 kcal week-1 during the final six weeks. Walking was carried out at an intensity of 67.8 (SD 4.99)% of maximum oxygen consumption and 73.8(6.99%) of maximum heart rate. Before and after the intervention all subjects underwent an M mode echocardiogram, graded treadmill walking test, and step test for the assessment of aerobic fitness. RESULTS: After 18 weeks the results of the control group showed no change in any of the variables measured while the walkers showed a statistically significant increase in the velocity of relaxation of the longitudinal myocardial fibres of the left ventricle and a decrease in heart rate measured during the step tests, indicating an improvement in aerobic capacity. CONCLUSIONS: Walking promotes improvements in cardiovascular fitness. Moderate forms of exercise may improve cardiac function.

Exploring adaptations to the modified shuttle walking test.

Objective The 10 m modified shuttle walking test (MSWT) is recommended to determine the functional capacity in older individuals and for patients entering cardiac rehabilitation. Participants are required to negotiate around cones set 1 m from the end markers. However, consistent comments indicate that for some individuals manoeuvring around the cones can be quite difficult. Therefore, the objective of this study was to explore differences within and between non-cardiac and postmyocardial infarction (MI) males during MSWT with and without the cones. Design Comparative study. Participants 20 post-MI (64.8±6.6, range 51–74 years) and 20 non-cardiac male controls (64.1±5.7, range 52–74 years) participated. Methods Participants performed MSWT with and without cones. Throughout, the participants expired air, and the heart rate (bpm) (HR) and ratings of perceived exertion (RPE) were measured. Participant protocol preference was recorded verbatim. Results One-way analysis of variance found no significant difference in VO2 peak (cones 20.4±5.1 vs no-cones 21.9±4.8 ml/kg/min, p=0.197) or distance ambulated (cones 631.8±132.9 m vs no-cones 662.4±164.1 m, p=0.371) between protocols or groups. Analysis comparing lines of regression showed a significant trajectory difference in VO2 (ml/kg/min) (p<0.01) between protocols with higher HR (p<0.01) and respiratory exchange ratio (RER, p<0.001) values during cones. RPEs were higher for post-MIs versus controls during both protocols (p<0.05). Post-MIs taking β-blockers produce significantly lower HR values. The χ2 analysis found no significant difference in protocol preference (no-cones: all n=25, 63%; post-MIs n=13, 65%; and controls n=12, 60%). Conclusions Post-MIs found both protocols subjectively harder than controls with no significant difference in the VO2 peak. However, both groups worked at a lesser percentage of their anaerobic threshold during no-cones protocol as indicated by lower RER values. Importantly, for the post-MIs, this would reduce their risk of functional impairment. Therefore, though more research is required, indicators at present are more favourable for the use of the no-cones with post-MIs.

Factor XIIa and triacylglycerol rich lipoproteins: responses to exercise intervention

Objectives—(a) To determine if factor XIIa (FXIIa) would be sensitive to change from exercise intervention in a group of previously sedentary/low active middle aged men and women; (b) to investigate further the previously reported relation between FXIIa and triacylglycerol (TAG) rich lipoproteins. Methods—Thirty seven men (mean (SD) age 57 (7) years) and 60 women (mean age 54 (7) years) completed the study. Before the intervention, these subjects were randomly allocated to a group of walkers (n = 81) or controls (n = 16). Before and after an 18 week walking intervention, fasted blood samples were collected and analysed for FXIIa, TAG, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and apolipoprotein (apo) B. Results—Kruskal-Wallis analysis of data obtained before the intervention showed no significant differences (p>0.4) between the walking and control groups for age, height, body mass, gender, FXIIa, TAG, TC, HDL-C, or apo B, although the women did show significantly lower levels of TAG (p<0.04) and higher HDL-C (p<0.0001) than the men. General linear model analysis of data obtained after the intervention, using the baseline value as a covariate, showed significant reductions (p<0.0001) in FXIIa for the walkers compared with the controls. Pearson product-moment correlations also showed significant relations between the concentrations of FXIIa and TAG, TC, LDL-C, and apo B. Conclusions—The findings of this study suggest that FXIIa is sensitive to change from exercise intervention and support previous research showing an association between the concentrations of FXIIa and TAG rich lipoproteins.

The lack of effectiveness of 18 weeks of accumulative short bouts of brisk walking upon the function of the heart

Cardiac function generally deteriorates with increasing age, although recent research has found a reversal in this decline in a group of middle‐aged individuals after 18 weeks of brisk walking in single daily bouts of between 20‐40 minutes. Government guidelines advocate accumulative short bouts of exercise for the promotion of health. The purpose of this study was to determine whether accumulative short walking bouts were as effective at producing changes in cardiac function as those previously found from single daily bouts. Presents the results of post‐intervention ANCOVA statistical analysis of 64 healthy men and women, aged 40‐68 years, who were not habitual exercisers, who were randomly divided into matched groups of either short walkers or controls who were also not habitual exercisers.

Appropriateness of the metabolic equivalent (MET) as an estimate of exercise intensity for post-myocardial infarction patients

Aims To explore: (1) whether during exercise metabolic equivalents (METs) appropriately indicate the intensity and/or metabolic cost for post-myocardial infarction (MI) males and (2) whether post-exercise VO2 parameters provide insight into the intensity and/or metabolic cost of the prior exercise. Methods 15 male phase-IV post-MIs (64.4±6.5 years) and 16 apparently healthy males (63.0±6.4 years) participated. Participants performed a graded cycle ergometer test (CET) of 50, 75 and 100 W, followed by 10 min active recovery (at 50 W) and 22 min seated recovery. Participants’ heart rate (HR, bpm), expired air parameters and ratings of perceived exertion (exercise only) were measured. Results General linear model analysis showed throughout significantly lower HR values in post-MI participants that were related to β-blocker medication (F (2,5)=18.47, p<0.01), with significantly higher VCO2/VO2 (F (2,5)=11.25, p<0.001) and gross kcals/LO2/min (F (2,5)=11.25, p<0.001). Analysis comparing lines of regression showed, during the CET: post-MI participants worked at higher percentage of their anaerobic threshold (%AT)/MET than controls (F (2,90)=18.98, p<0.001), as well as during active recovery (100–50 W) (F (2,56)=20.81, p<0.001); during seated recovery: GLM analysis showed significantly higher values of VCO2/VO2 for post-MI participants compared with controls (F (2,3)=21.48, p=0.001) as well as gross kcals/LO2/min (F (2,3)=21.48, p=0.001). Conclusion Since METs take no consideration of any anaerobic component, they failed to reflect the significantly greater anaerobic contribution during exercise per MET for phase-IV post-MI patients. Given the anaerobic component will be greater for those with more severe forms of cardiac disease, current METs should be used with caution when determining exercise intensity in any patient with cardiac disease.

Young children’s physical activity levels in primary (elementary) schools: what impact does physical education lessons have for young children?

ABSTRACT Objectives: This paper explores the impact of physical education (PE) lessons, focusing on children aged 6–7 years, an underrepresented age in physical activity research. Methods: 10 children wore Actigraph accelerometers recording physical activity throughout the school day (9 am until 3.10 pm), for a year. Repeated measures ANOVA analysed: type of day (days including PE and days that did not) and gender (p < .05). Results: Boys achieved 88% (girls 70%) of the recommended daily physical activity levels on PE days compared to 77% (girls 63%) on non-PE days. Significant differences occurred, boys more active than girls also PE days being more active than non-PE days. Conclusion: The novel findings indicate PE lessons significantly contributes to children’s physical activity levels.

Metabolic equivalents fail to indicate metabolic load in post-myocardial infarction patients during the modified Bruce treadmill walking test

Aim To investigate the suitability of metabolic equivalents (METs) for determining exercise intensity in phase-IV post-myocardial infarction (MI) men during the modified Bruce treadmill walking test (MBWT). Methods Twenty phase-IV post-MI men (mean±SD, aged 64.4±5.8 years) and 20 healthy non-cardiac male controls (59.8±7.6 years) participated. Participants performed a MBWT. Throughout the participants’ heart rate (HR), heart rhythm, expired air parameters and ratings of perceived exertion (RPEs) were measured. MET values were compared between groups and those currently ascribed to each stage of the MBWT. Results General linear model analysis found no significant differences between groups during the MBWT for VO2, VCO2, HR, METs or RPEs (Borg 6–20 scale). Ascribed METs did not differ from mean METs of post-MIs or controls other than at stage 5 where post-MI METs were significantly lower. Irrespective, the post-MI group worked at a higher percentage of their anaerobic threshold (AT) (respiratory exchange ratio, RER=1.0) (F (2,5)=7.22, p<0.008), higher RER (F (2,5)=11.25, p<0.001) with increased breathing frequency (F (2,5)=7.22, p<0.001). Regression analysis revealed AT to be VO2 25.6 (mL/kg/min) for post-MI versus VO2 31.1 (mL/kg/min) for controls. Gross energy expenditure (kcal/min) was greater for the post-MI group compared with controls (F (2,5)=11.22, p<0.001). Throughout the MBWT, post-MI group worked at a higher %AT/MET than controls (F (2,196)=211.76, p<0.01). Body composition did not strongly influence %AT/MET, parameters of VO2, METs or RPE. Conclusion During the MBWT, post-MI men worked more anaerobically per MET (%AT/MET) than controls. Therefore, current METs based on non-cardiac individuals appear unsuitable in determining the full metabolic load of the exercise intensity for cardiac patients during the MBWT.

24 Weeks of Walking Decreases Waist Circumference and Enhances Insulin Sensitivity in Previously Sedentary Men: 1415

Insulin resistance in the presence of obesity, especially high abdominal fat levels (of which men are particularly prone), are prime risk factors for type II diabetes and metabolic syndrome (MetS), and a sedentary lifestyle is a known contributor for these. Walking is accessible exercise for the majority of the population but there is still relatively little empirical research looking directly at its effect upon all prime MetS risk factors.PURPOSE: To determine whether 24 weeks of walking for 30 min·d-1 on at least 5 d·wk-1 affected prime MetS risk factors and insulin sensitivity in previously sedentary men.METHODS: 48 (28.4±3.2 BMI) low-active/sedentary men were randomly selected into controls (n=19, 52.4±8.0) or walkers (n=29, 54.9±8.0 years). Walking diaries indicated intensity, duration and compliance. Pre- and post-intervention criterion MetS measures were taken in addition to insulin (insulin sensitivity index (ISI) derived) and treadmill-walking VO2max. Fasted venous blood samples were taken. The GLM was employed using baseline covariate measures. Bonferroni correction was applied which set statistical significance at P<0.006.RESULTS: Over 24-weeks 156.4±26.5 min·walking·wk-1 was performed in 7.2±2.9 sessions·wk-1 for a mean of 25.1±10.3 min·session-1 at 50.6±9.1% estimated VO2max mL·kg-1·min-1. Significant post-intervention changes were observed in waist circumference (WC) (walkers -2.0±2.7 vs. controls +1.3±3.1 cm, F=15.27, P<0.0001); W/H ratio (-0.02 ±0.03 vs. +0.01±0.03, F=19.82, P<0.0001), serum insulin (-1.7±1.5 vs. +2.0±6.0, F=8.40, P<0.006 μU·ml-1) and ISI (+2.0±6.0 vs. -0.4±0.7, F=10.82, P<0.002 M·mU-1·L-1, respectively). No significant effect was observed in levels of triglyceride, high-density lipoprotein cholesterol, blood pressure, or blood glucose. Post-intervention changes for insulin correlated with WC (R=0.441; R2=0.19: P<0.002); and ISI negatively with WC (R=-0.433; R2=0.19: P<0.003).CONCLUSIONS: Given the importance of insulin resistance in the presence of abdominal obesity, these findings demonstrate around 30 min·d-1 of walking on at least 5 d·wk-1 at an easily attainable intensity for most adults (∼51% VO2max) can reduced WC, which appeared to enhance insulin sensitivity, thereby helping reduce risk of type II diabetes and MetS.