John P. Buckley

Reliability and validity of measures taken during the Chester step test to predict aerobic power and to prescribe aerobic exercise

Objectives: To evaluate the reliability and validity of measures taken during the Chester step test (CST) used to predict VO2max and prescribe subsequent exercise. Methods: The CST was performed twice on separate days by 7 males and 6 females aged 22.4 (SD 4.6) years. Heart rate (HR), ratings of perceived exertion (RPE), and oxygen uptake (VO2) were measured at each stage of the CST. Results: RPE, HR, and actual VO2 were the same at each stage for both trials but each of these measures was significantly different between CST stages (p<0.0005). Intertrial bias ±95% limits of agreement (95% LoA) of HR reached acceptable limits at CST stage IV (−2±10 beats/min) and for RPE at stages III (0.2±1.4) and IV (0.5±1.9). Age estimated HRmax significantly overestimated actual HRmax of 5 beats/min (p = 0.016) and the 95% LoA showed that this error could range from an underestimation of 17 beats/min to an overestimation of 7 beats/min. Estimated versus actual VO2 at each CST stage during both trials showed errors ranging between 11% and 19%. Trial 1 underestimated actual VO2max by 2.8 ml/kg/min (p = 0.006) and trial 2 by 1.6 ml/kg/min (not significant). The intertrial agreement in predicted VO2max was relatively narrow with a bias ±95% LoA of −0.8±3.7 ml/kg/min. The RPE and %HRmax (actual) correlation improved with a second trial. At all CST stages in trial 2 RPE:%HRmax coefficients were significant with the highest correlations at CST stages III (r = 0.78) and IV (r = 0.84). Conclusion: CST VO2max prediction validity is questioned but the CST is reliable on a test-retest basis. VO2max prediction error is due more to VO2 estimation error at each CST stage compared with error in age estimated HRmax. The HR/RPE relation at >50% VO2max reliably represents the recommended intensity for developing cardiorespiratory fitness, but only when a practice trial of the CST is first performed.

McArdle disease: a clinical review.

Methods The clinical phenotype of 45 genetically confirmed McArdle patients is described. Results In the majority of patients (84%), the onset of symptoms was from early childhood but diagnosis was frequently delayed until after 30 years of age. Not all patients could recognise a second wind although it was always seen with exercise assessment. A history of myoglobinuria was not universal and episodes of acute renal failure had occurred in a minority (11%). The condition does not appear to adversely affect pregnancy and childbirth. Clinical examination was normal in most patients, muscle hypertrophy was present in 24% and mild muscle wasting and weakness were seen only in patients over 40 years of age and was limited to shoulder girdle and axial muscles. The serum creatine kinase was elevated in all but one pregnant patient. Screening for the mutations pArg50X (R50X) and pGly205Ser (G205S) showed at least one mutated allele in 96% of Caucasian British patients, with an allele frequency of 77% for pArg50X in this population. A 12 min walking test to evaluate patients is described. Conclusion The results demonstrated a wide spectrum of severity with the range of distance walked (195–1980 m); the mean distance walked was 512 m, suggesting significant functional impairment in most patients.

The sedentary office: an expert statement on the growing case for change towards better health and productivity

An international group of experts convened to provide guidance for employers to promote the avoidance of prolonged periods of sedentary work. The set of recommendations was developed from the totality of the current evidence, including long-term epidemiological studies and interventional studies of getting workers to stand and/or move more frequently. The evidence was ranked in quality using the four levels of the American College of Sports Medicine. The derived guidance is as follows: for those occupations which are predominantly desk based, workers should aim to initially progress towards accumulating 2 h/day of standing and light activity (light walking) during working hours, eventually progressing to a total accumulation of 4 h/day (prorated to part-time hours). To achieve this, seated-based work should be regularly broken up with standing-based work, the use of sit–stand desks, or the taking of short active standing breaks. Along with other health promotion goals (improved nutrition, reducing alcohol, smoking and stress), companies should also promote among their staff that prolonged sitting, aggregated from work and in leisure time, may significantly and independently increase the risk of cardiometabolic diseases and premature mortality. It is appreciated that these recommendations should be interpreted in relation to the evidence from which they were derived, largely observational and retrospective studies, or short-term interventional studies showing acute cardiometabolic changes. While longer term intervention studies are required, the level of consistent evidence accumulated to date, and the public health context of rising chronic diseases, suggest initial guidelines are justified. We hope these guidelines stimulate future research, and that greater precision will be possible within future iterations.

Standing-based office work shows encouraging signs of attenuating post-prandial glycaemic excursion

Objectives The main aim of this study was to compare two days of continuous monitored capillary blood glucose (CGM) responses to sitting and standing in normally desk-based workers. Design, setting and participants This open repeated-measures study took place in a real office environment, during normal working hours and subsequent CGM overnight measures in 10 participants aged 21–61 years (8 female). Main outcomes Postprandial (lunch) measures of: CGM, accelerometer movement counts (MC) heart rate, energy expenditure (EE) and overnight CGM following one afternoon of normal sitting work compared with one afternoon of the same work performed at a standing desk. Results Area-under-the-curve analysis revealed an attenuated blood glucose excursion by 43% (p=0.022) following 185 min of standing (143, 95% CI 5.09 to 281.46 mmol/L min) compared to sitting work (326; 95% CI 228 to 425 mmol/L min). Compared to sitting, EE during an afternoon of standing work was 174 kcals greater (0.83 kcals/min; p=0.028). The accelerometer MC showed no differences between the afternoons of seated versus standing work; reported differences were thus a function of the standing work and not from additional physical movements around the office. Conclusions This is the first known ‘office-based’ study to provide CGM measures that add some of the needed mechanistic information to the existing evidence-base on why avoiding sedentary behaviour at work could lead to a reduced risk of cardiometabolic diseases.

Physiologic responses and energy expenditure of kinect active video game play in schoolchildren.

OBJECTIVE To evaluate the physiologic responses and energy expenditure of active video gaming using Kinect for the Xbox 360. DESIGN Comparison study. SETTING Kirkby Sports College Centre for Learning, Liverpool, England. PARTICIPANTS Eighteen schoolchildren (10 boys and 8 girls) aged 11 to 15 years. MAIN EXPOSURE A comparison of a traditional sedentary video game and 2 Kinect activity-promoting video games, Dance Central and Kinect Sports Boxing, each played for 15 minutes. Physiologic responses and energy expenditure were measured using a metabolic analyzer. MAIN OUTCOME MEASURES Heart rate, oxygen uptake, and energy expenditure. RESULTS Heart rate, oxygen uptake, and energy expenditure were considerably higher (P < .05) during activity-promoting video game play compared with rest and sedentary video game play. The mean (SD) corresponding oxygen uptake values for the sedentary, dance, and boxing video games were 6.1 (1.3), 12.8 (3.3), and 17.7 (5.1) mL · min-1 · kg-1, respectively. Energy expenditures were 1.5 (0.3), 3.0 (1.0), and 4.4 (1.6) kcal · min-1, respectively. CONCLUSIONS Dance Central and Kinect Sports Boxing increased energy expenditure by 150% and 263%, respectively, above resting values and were 103% and 194% higher than traditional video gaming. This equates to an increased energy expenditure of up to 172 kcal · h-1 compared with traditional sedentary video game play. Played regularly, active gaming using Kinect for the Xbox 360 could prove to be an effective means for increasing physical activity and energy expenditure in children.

Ratings of perceived exertion in braille: validity and reliability in production mode.

Objectives—(a) To assess the validity and reliability of producing and reproducing a given exercise intensity during cycle ergometry using a braille version of Borgs standard 6–20 rating of perceived exertion (RPE) scale, and (b) to determine whether the exercise responses of blind participants, at a given produced RPE, were similar to those reported in recognised guidelines for sighted subjects. Methods—Ten healthy registered blind volunteer participants (four women, six men; mean (SD) age 23.2 (9.0) years) performed an initial graded exercise cycle test to determine maximal heart rate (HRmax) and maximal oxygen uptake (Vo2max). Three trials of three exercise bouts at RPEs 9, 11, and 13 were then performed in random order on three separate days of the same week, with expired air and heart rate measured continuously. Each exercise bout was followed by 10 minutes of rest. The validity of the scale as a means of producing different exercise intensities was assessed using a two factor (RPE × trial) repeated measures analysis of variance. Intertrial reliability was assessed using intraclass correlation coefficients (ICC) and the bias ±95% limits of agreement (95%LoA) procedure. Results—Participants reported no difficulty in using the braille RPE scale. When asked to produce exercise intensities equating to RPE 9, 11, and 13, they elicited mean %Vo2max values of 47%, 53%, and 63% respectively. Analysis of variance showed no significant differences in either %HRmax or %Vo2max between trials at each of the three RPEs, but there was a significant difference (p<0.001) in both %HRmax and %Vo2max between the three RPE levels. All pairwise comparisons of the three different RPEs were significantly different (p<0.016). The ICC between the second and third trial for %HRmax was significant (p <0.05) for all three RPEs. Similarly for %Vo2max, the ICC was significant for RPE 9 and 11 but not 13. The 95%LoA decreased for both %HRmax and %Vo2max with each successive trial. Conclusions—Blind participants were successful in using a braille RPE scale to differentiate exercise intensity on a cycle ergometer. In every trial at RPE 13, all participants achieved %HRmax and %Vo2max levels, which fell within the recommended range for developing cardiorespiratory fitness. Using %HRmax as a judge of intertrial reliability, the participants were able to repeat similar exercise intensities after two trials at each of the three RPEs (9, 11,13). The same was true for RPE 9 and 11, when %Vo2max was used as a judge, but further trials were required to achieve similar reliability at RPE 13. A braille RPE scale can be used by healthy blind people during cycle ergometry, with similar effect to the visual analogue scale recommended for use in healthy sighted people.

The sedentary office: a growing case for change towards better health and productivity. Expert statement commissioned by Public Health England and the Active Working Community Interest Company

An international group of experts convened to provide guidance for employers to promote the avoidance of prolonged periods of sedentary work. The set of recommendations was developed from the totality of the current evidence, including long-term epidemiological studies and interventional studies of getting workers to stand and/or move more frequently. The evidence was ranked in quality using the four levels of the American College of Sports Medicine. The derived guidance is as follows: for those occupations which are predominantly desk based, workers should aim to initially progress towards accumulating 2 h/day of standing and light activity (light walking) during working hours, eventually progressing to a total accumulation of 4 h/day (prorated to part-time hours). To achieve this, seated-based work should be regularly broken up with standing-based work, the use of sit–stand desks, or the taking of short active standing breaks. Along with other health promotion goals (improved nutrition, reducing alcohol, smoking and stress), companies should also promote among their staff that prolonged sitting, aggregated from work and in leisure time, may significantly and independently increase the risk of cardiometabolic diseases and premature mortality. It is appreciated that these recommendations should be interpreted in relation to the evidence from which they were derived, largely observational and retrospective studies, or short-term interventional studies showing acute cardiometabolic changes. While longer term intervention studies are required, the level of consistent evidence accumulated to date, and the public health context of rising chronic diseases, suggest initial guidelines are justified. We hope these guidelines stimulate future research, and that greater precision will be possible within future iterations.

PREDICTING MAXIMAL OXYGEN UPTAKE VIA A PERCEPTUALLY REGULATED EXERCISE TEST (PRET)

Recent research has yielded encouraging, yet inconsistent findings concerning the validity and reliability of predicting maximal oxygen uptake ( O 2max ) from a graded perceptually regulated exercise test (PRET). Accordingly, the purpose of the present study was to revisit the validity and reliability of this application of ratings of perceived exertion (RPE) using a modified PRET protocol. Twenty-three volunteers (mean age, 31 ± 9.9 years) completed four counter-balanced PRETs (involving two 2-minute and two 3-minute bouts administered over 9 days, each separated by 48 hours) on an electromagnetically braked cycle ergometer and one maximal graded exercise test. Participants self-regulated their exercise at RPE levels 9, 11, 13, 15 and 17 in a randomized order. Oxygen uptake ( O 2 ) was recorded continuously during each bout. The O 2 values for the RPE ranges 9–17, 9–15 and 9–13 were extrapolated to RPE 20 using regression analysis to predict individual O 2max scores. The concordance of the predicted and actual O 2max scores and the trial-to-trial reliability of the predicted scores were analyzed using the limits of agreement (LoA) technique. The LoA between actual (41.5 ± 8.0 mL·kg −1 ·min −1 ) and predicted O 2max scores for the RPE range 9–17 were −2.6 ± 10.1 and −1.3 ± 7.4 mL·kg −1 ·min −1 (2-minute bout) and −1.0 ± 9.2 and 0.2 ± 7.2 mL·kg −1 ·min −1 (3-minute bout) for trials 1 and 2, respectively. Reliability analysis yielded LoA of −1.3 ± 9.2 mL·kg −1 ·min −1 (2-minute bout) and −0.8 ± 5.7 mL·kg −1 ·min −1 (3-minute bout). The modified PRET provided acceptable and repeatable estimates of O 2max , suggesting its application in environments where maximal tests are inappropriate, and is worthy of further investigation.

Cardiac Rehabilitation Delivery Model for Low-Resource Settings: An International Council of Cardiovascular Prevention and Rehabilitation Consensus Statement.

Cardiovascular disease (CVD) is a global epidemic, which is largely preventable. Cardiac rehabilitation (CR) is demonstrated to be efficacious and cost-effective for secondary prevention in high-income countries. Given its affordability, CR should be more broadly implemented in middle-income countries as well. Hence, the International Council of Cardiovascular Prevention and Rehabilitation (ICCPR) convened a writing panel to recommend strategies to deliver all core CR components in low-resource settings, namely: (1) initial assessment, (2) lifestyle risk factor management (i.e., diet, tobacco, mental health), (3) medical risk factor management (lipids, blood pressure), (4) education for self-management; (5) return to work; and (6) outcome evaluation. Approaches to delivering these components in alternative, arguably lower-cost settings, such as the home, community and primary care, are provided. Recommendations on delivering each of these components where the most-responsible CR provider is a non-physician, such as an allied healthcare professional or community health care worker, are also provided.

The role of lactate in the exercise-induced human growth hormone response: evidence from McArdle disease

Purpose: Increased blood lactate concentration has been suggested as a primary stimulus for the exercise-induced growth hormone response (EIGR). Patients with McArdle disease are unable to produce lactate in response to exercise and thus offer a unique model to assess the role of lactate in the EIGR. Accordingly, McArdle’s patients were exercised to test the hypothesis that lactate is a major stimulus of the EIGR. Methods: 11 patients with McArdle disease (3 male, 8 female; age: 35.5 (SD 13.9) years, height: 166 (8) cm, body mass: 75.2 (13.1) kg) were recruited for the study. The patients walked initially at 0.42 m/s, increasing by 0.14 m/s per 3 min stage. Exercise was terminated when participants completed 3 minutes at 1.80 m/s or when a Borg CR10 pain scale rating of “4” was reached. Stages were separated by 60 s for capillary blood sampling for analysis of hGH and blood lactate concentration. Results: McArdle’s patients’ blood lactate levels remained at resting levels (0.3–1.2 mmol/l) as exercise intensity increased. Nine out of 11 participants failed to demonstrate an EIGR obtaining hGH values below the clinical definition of a response (>3 μg/l). Conclusion: The absence of an EIGR in nine out of 11 participants suggests that lactate could play a major role in the EIGR in humans.