Danielle Lambrick

Prediction of maximal oxygen uptake in sedentary males from a perceptually regulated, sub-maximal graded exercise test

Abstract The purpose of this study was to assess the validity of predicting the maximal oxygen uptake ([Vdot]O2max) of sedentary men from sub-maximal [Vdot]O2 values obtained during a perceptually regulated exercise test. Thirteen healthy, sedentary males aged 29 – 52 years completed five graded exercise tests on a cycle ergometer. The first and fifth test involved a graded exercise test to determine [Vdot]O2max. The two maximal graded exercise tests were separated by three sub-maximal graded exercise tests, perceptually regulated at 3-min RPE intensities of 9, 11, 13, 15, and 17 on the Borg ratings of perceived exertion (RPE) scale, in that order. After confirmation that individual linear regression models provided the most appropriate fit to the data, the regression lines for the perceptual ranges 9 – 17, 9 – 15, and 11 – 17 were extrapolated to RPE 20 to predict [Vdot]O2max. There were no significant differences between [Vdot]O2max values from the graded exercise tests (mean 43.9 ml · kg−1 · min−1, s = 6.3) and predicted [Vdot]O2max values for the perceptual ranges 9 – 17 (40.7 ml · kg−1 · min−1, s = 2.2) and RPE 11 – 17 (42.5 ml · kg−1 · min−1, s = 2.3) across the three trials. The predicted [Vdot]O2max from the perceptual range 9 – 15 was significantly lower (P < 0.05) (37.7 ml · kg−1 · min−1, s = 2.3). The intra-class correlation coefficients between actual and predicted [Vdot]O2max for RPE 9 – 17 and RPE 11 – 17 across trials ranged from 0.80 to 0.87. Limits of agreement analysis on actual and predicted [Vdot]O2 values (bias ± 1.96 × s diff) were 3.4 ml · kg−1 · min−1 (±10.7), 2.4 ml · kg−1 · min−1 (±9.9), and 3.7 ml · kg−1 · min−1 (±12.8) (trials 1, 2, and 3, respectively) of RPE range 9 – 17. Results suggest that a sub-maximal, perceptually guided graded exercise test provides acceptable estimates of [Vdot]O2max in young to middle-aged sedentary males.

The perceptual response to exercise of progressively increasing intensity in children aged 7–8 years: Validation of a pictorial curvilinear ratings of perceived exertion scale

This study assessed the validity of the Eston-Parfitt (E-P) curvilinear Ratings of Perceived Exertion (RPE) Scale and a novel marble quantity task to provide estimates of perceived exertion during cycle ergometry. Fifteen children aged 7-8 years performed a discontinuous incremental graded-exercise test, and reported exertional ratings at the end of each minute. Significant increases in physiological and perceptual data were observed with increasing work rate. The relationship between work rate and marbles was curvilinear (mean R(2)=.94), supporting the theoretical justification for the E-P Scale. Strong linear (R(2)=.93) and curvilinear (R(2)=.94) relationships between RPE from the E-P Scale and work rate confirmed the robustness of the E-P Scale. Valid exertional ratings may be obtained using the E-P Scale with young children. The novel marble quantity task offers an alternative method of deriving perceived exertion responses in children.

Effects of Early Exercise Engagement on Vascular Risk in Patients with Transient Ischemic Attack and Nondisabling Stroke

The objective of this study was to conduct a randomized, parallel-group clinical trial assessed the efficacy of a health-enhancing physical activity program (exercise and education) on vascular risk factors and aerobic fitness in patients who have experienced a transient ischemic attack (TIA) or nondisabling stroke. Sixty patients (69±11 years) completed a baseline (BL) vascular risk stratification and aerobic fitness examination (cycle test) within 2 weeks of symptom onset. Subjects were then randomized to either an 8-week, twice weekly exercise program or to a usual-care control (CON) group. Postintervention (PI) assessments were completed immediately after the intervention and at 3-month follow-up. A series of primary (systolic blood pressure [SBP]) and secondary (vascular risk factors like total cholesterol [TC], high-density lipoproteins, etc.; Framingham risk score; peak oxygen uptake) outcome measures were assessed. Significantly greater reductions in SBP (mean change±SD; -10.4±9.2 mm Hg) and TC (-.53±.90 mmol/L) were observed between BL and PI assessments for the exercise group compared with the CON group (-1.9±15.4 mm Hg and -.08±.59 mmol/L, respectively) (P<.05). These improvements were maintained between the PI and the 3-month follow-up assessment (P>.05). Significant improvements in aerobic fitness were also observed and maintained at the 3-month follow-up assessment after regular exercise participation (P<.05). The early engagement in exercise resulted in significant improvements in vascular risk factors and fitness in those diagnosed with TIA. As these beneficial effects were maintained up to 3 months after completing the exercise program, exercise should be considered a useful additive treatment strategy for newly diagnosed TIA patients. Future research should examine the long-term efficacy of such programs.

Validation of Oscillometric Pulse Wave Analysis Measurements in Children

BACKGROUND Pulse wave analysis (PWA) has emerged as a noninvasive, valid, reliable, and widely used technique to investigate central blood pressures and systemic arterial wave reflection (augmentation index). The gold-standard technique is tonometry, but this technique can be challenging, especially when used on children. The purpose of this study was to validate oscillometric PWA for use in children. METHODS Fifty-seven healthy children were recruited for participation. Central blood pressures and peripheral augmentation index (pAIx) were measured objectively using oscillometric (Pulsecor R7) and tonometric (SphygmaCor) devices. All measurements were made during the same visit under standardized conditions between the hours of 8 am and 10 am in the fasted state. RESULTS Tonometric measurements were unsuccessful on 1 child. Comparisons were made on 56 children (mean age = 9.8±1.0 y; 57% male). A very strong relationship was found between devices for central systolic (r = 0.94; P < 0.001), diastolic (r = 0.99; P < 0.001) and mean (r = 0.96; P < 0.001) blood pressures. However, Bland-Altman analysis indicated a bias toward greater systolic blood pressures with the oscillometric monitor (mean difference = 4.5mm Hg; 95% confidence interval (CI) = -5.16 to -3.89). A good relationship was found for pAIx (r = 0.71; P < 0.001); the mean difference between devices was -1.70% (95% CI = -4.47% to 1.08%), which is not significantly different from zero. CONCLUSIONS Findings from this study suggest that oscillometric PWA provides valid measures of central blood pressure and arterial wave reflection in children aged 8-10 years.

The effectiveness of a high-intensity games intervention on improving indices of health in young children

Abstract This study assessed the effectiveness of a 6-week, high-intensity, games-based intervention on physiological and anthropometric indices of health, in normal weight (n = 26; 32.5 ± 8.9 kg) and obese (n = 29; 49.3 ± 8.9 kg) children (n = 32 boys, 23 girls), aged 8–10 years. Children were randomised into an exercise or control group. The exercise group participated in a twice-weekly, 40 min active games intervention, alongside their usual school physical education classes. The control group did not take part in the intervention. Before and after the intervention, participants completed both a maximal and submaximal graded exercise test. The submaximal exercise test comprised of a 6 min, moderate- and 6 min heavy-intensity bout, interspersed with a 5 min recovery. The exercise group demonstrated improvements in maximal oxygen uptake (51.4 ± 8.5 vs 54.3 ± 9.6 ml · kg−1 · min−1) and peak running speed (11.3 ± 1.6 vs 11.9 ± 1.6 km · h−1), and a reduction in the oxygen cost of submaximal exercise between assessments (P < .05). A decrease in waist circumference and increase in muscle mass were observed between assessments for the obese participants randomised to the intervention (both P < .05). This study demonstrates that a short-term, high-intensity games intervention may elicit positive changes in physiological and anthropometric indices of health in normal weight and obese children.

The Efficacy of a Self-Paced VO2max Test During Motorized Treadmill Exercise

PURPOSE To assess the utility of a self-paced maximal oxygen uptake (VO2max) test (SPV) in eliciting an accurate measure of VO2max in comparison with a traditional graded exercise test (GXT) during motorized treadmill exercise. DESIGN This was a cross-sectional experimental study whereby recreationally trained men (n = 13, 25.5 ± 4.6 y) completed 2 maximal exercise tests (SPV, GXT) separated by a 72-h recovery period. METHODS The GXT was continuous and incremental, with prescribed 1-km/h increases every 2 min until the attainment of VO2max. The SPV consisted of 5 × 2-min stages of incremental exercise, which were self-selected and adjusted according to 5 prescribed RPE levels (RPE 11, 13, 15, 17, and 20). RESULTS Although no significant differences in VO2max were observed between the SPV and GXT (63.9 ± 3.3 cf 60.9 ± 4.6 mL · kg-1 · min-1, respectively, P > .05), the apparent 4.7% mean difference may be practically important. The 95% limits-of-agreement analysis was 3.03 ± 11.49 mL · kg-1 · min-1. Therefore, in the worst-case scenario, the GXT may underestimate measured VO2max as ascertained by the SPV by up to 19%. Conversely, the SPV could underestimate the GXT by 14%. CONCLUSIONS The current study has shown that the SPV is an accurate measure of VO2max during exercise on a motorized treadmill and may provide a slightly higher VO2max value than that obtained from a traditional GXT. The higher VO2max during the SPV may be important when prescribing training or monitoring athlete progression.

Reliability of oscillometric central blood pressure and wave reflection readings: effects of posture and fasting.

Objective: Oscillometric pulse wave analysis devices have recently emerged, presenting suitable options for investigating central hemodynamic properties in clinical practice. This study sought to examine whether the between-day reliability of central SBP (cSBP) and systemic arterial wave reflection (augmentation index, AIx) readings exceed the criterion for acceptable reliability or are affected by posture (supine and seated) and fasting state. Methods: Twenty healthy adults (50% female, 27.9 years, 24.2 kg/m2) were tested on six different mornings: 3 days fasted and 3 days nonfasted. On each occasion, participants were tested in supine and seated postures. Oscillometric pressure waveforms were recorded on left upper arm. Results: For cSBP, there was nonsignificant main effect for fasting state (P = 0.819) but there was a main effect for posture (P = 0.002). Conversely, for AIx, there was nonsignificant main effect for posture (P = 0.537) but there was a large main effect for fasting state (P = < 0.001). The criterion intraclass correlation coefficient value of 0.75 was exceeded for both variables when participants were assessed under the combined supine-fasted condition. For cSBP, the reliability coefficient was lowest (best) when supine fasted (6.8 mmHg) and greatest (worst) when seated nonfasted (8.6 mmHg). For AIx, the reliability coefficient was lower for the supine (11.4–11.7%) compared with the seated (14.0–15.2%) posture. Conclusion: Findings from this study suggest that oscillometric assessments of central hemodynamic variables exceed the criterion for acceptable reliability and are most reliable when participants are evaluated while supine and fasted.

Modifiable Cardiovascular Disease Risk Factors among Indigenous Populations

Objective. To identify modifiable cardio-metabolic and lifestyle risk factors among indigenous populations from Australia (Aboriginal Australians/Torres Strait Islanders), New Zealand (Māori), and the United States (American Indians and Alaska Natives) that contribute to cardiovascular disease (CVD). Methods. National health surveys were identified where available. Electronic databases identified sources for filling missing data. The most relevant data were identified, organized, and synthesized. Results. Compared to their non-indigenous counterparts, indigenous populations exhibit lower life expectancies and a greater prevalence of CVD. All indigenous populations have higher rates of obesity and diabetes, hypertension is greater for Māori and Aboriginal Australians, and high cholesterol is greater only among American Indians/Alaska Natives. In turn, all indigenous groups exhibit higher rates of smoking and dangerous alcohol behaviour as well as consuming less fruits and vegetables. Aboriginal Australians and American Indians/Alaska Natives also exhibit greater rates of sedentary behaviour. Conclusion. Indigenous groups from Australia, New Zealand, and the United States have a lower life expectancy then their respective non-indigenous counterparts. A higher prevalence of CVD is a major driving force behind this discrepancy. A cluster of modifiable cardio-metabolic risk factors precede CVD, which, in turn, is linked to modifiable lifestyle risk factors.

The effect of a short-term exercise programme on haemodynamic adaptability; a randomised controlled trial with newly diagnosed transient ischaemic attack patients

This study assessed the effect of a short-term, 8-week exercise programme on resting and exercise blood pressure (systolic (SBP); diastolic (DBP)), and other haemodynamic responses (heart rate (HR), pulse pressure (PP), double product (DP)), of newly diagnosed transient ischaemic attack (TIA) patients. Sixty-eight TIA patients completed a continuous and incremental exercise test within 2 weeks of symptom diagnosis. HR, SBP and DBP were regularly measured at rest, during exercise and in recovery. Participants were then randomised to either an 8-week exercise programme or to a usual care control group prior to completing an identical post-intervention (PI) re-assessment. Individuals randomised to the exercise condition experienced a significantly greater reduction in resting HR (−5.4±10.2%), SBP (−6.7±8.1%) and DBP (−2.8±7.2%) than the control group at the PI assessment (all P<0.05). Similar findings were demonstrated at the PI assessment when comparing haemodynamic responses during exercise (P<0.05), with significantly larger decrements observed for SBP and HR (both 10–14%), PP (17–24%) and DP (26–32%) for those randomised to the exercise intervention (all P<0.05). This study demonstrates that structured physical activity soon after TIA diagnosis will improve haemodynamic responses. The early implementation of exercise following TIA diagnosis may be an important secondary prevention strategy for this population.

Effects of continuous and intermittent exercise on executive function in children aged 8–10 years

Understanding the effects of acute exercise on executive function in prepubescent children may be important for the enhancement of school performance. This study assessed the effect of an acute bout of continuous (CONT) or intermittent (INT), moderate-intensity treadmill exercise on executive function in young children. Twenty healthy children, mean (SD); age: 8.8 (0.8) years; height: 140 (9) cm; weight: 36 (11) kg; boys: n = 9, performed a graded-exercise test to determine maximal oxygen uptake, and two 15-min submaximal bouts of treadmill exercise; protocols were either CONT or INT. During CONT, participants ran at 90% of gas exchange threshold. During INT, participants performed six consecutive 2.5 min blocks of exercise, which were designed to reflect childrens typical activity patterns, comprising 45 s at a heavy intensity, 33 s at a moderate intensity, 10 s at a severe intensity, and 62 s at a low intensity. Participants performed the Stroop task before the submaximal exercise bouts and after, at 1-, 15-, and 30-min intervals. Near-infrared spectroscopy (NIRS) measured cerebral perfusion and oxygenation. Regardless of condition, Stroop performance was improved at 1 min after compared to before, 54.9 (9.8) s versus 57.9 (11) s, respectively, p < .01, and improvements were maintained until 30 min after. NIRS (oxyhemoglobin, total hemoglobin) explained a significant amount of variance in the change in Stroop performance for INT only (49%, p < .05). An acute bout of exercise, of either an intermittent or continuous nature, improves executive function in children, and effects are maintained for ≤ 30 min following exercise cessation. Accordingly, it is recommended that children should engage in physical activity during periods of school recess.