Giovanni Grazzi

Identification of a Oo2 Deflection Point Coinciding With the Heart Rate Deflection Point and Ventilatory Threshold in Cycling

Grazzi, G, Mazzoni, G, Casoni, I, Uliari, S, Collini, G, van der Heide, L, and Conconi, F. Identification of a &OV0312;o2 deflection point coinciding with the heart rate deflection point and ventilatory threshold in cycling. J Strength Cond Res 22: 1116-1123, 2008-The purposes of this study were to compare the patterns of the work rate (WR)-&OV0312;o2 and WR-heart rate (HR) relationships in incremental cycling, to ascertain the occurrence of a &OV0312;o2 deflection (&OV0312;o2def) coinciding with the HR deflection point (HRdef ), and to determine whether the &OV0312;o2def, if present, coincides with the ventilatory anaerobic threshold (VT). Twenty-four professional cyclists performed a maximal incremental test on a wind-load cycle ergometer. Work rate, HR, &OV0312;o2, and &OV0312;co2 were recorded. The WR-&OV0312;o2 relationships obtained were linear up to submaximal WR and curvilinear thereafter and thus described a &OV0312;o2def. The WR and &OV0312;o2 at &OV0312;o2def were mathematically determined for all subjects. The ratio of ΔWR·Δ&OV0312;o2−1 up to &OV0312;o2def was significantly lower than that above &OV0312;o2def (90 ± 11 W·L−1·min−1 versus 133 ± 35 W·L−1·min−1, p < 0.0001). The WR-HR relationships obtained were linear up to submaximal WR and curvilinear thereafter. The WR and HR at HRdef were mathematically determined for all subjects. The WR values at &OV0312;o2def and at HRdef (329 ± 32 W and 326 ± 34 W) were significantly correlated (R2 = 0.96, p < 0.0001) and in good concordance (limits of agreement from -4.7% to 3.2%, Bland-Altman analysis). The &OV0312;o2 at VT was then determined for all subjects. The &OV0312;o2 values at &OV0312;o2def and at VT were significantly correlated (R2 = 0.99, p < 0.0001) and in strong concordance (limits of agreement from -1.9% to 1.0%, Bland-Altman analysis). In conclusion, a &OV0312;o2def coinciding with HRdef and VT was shown. This confirms that the determination of the WR-HR relationship and of HRdef is a practical and noninvasive means of identifying anaerobic threshold.

Treadmill walking speed and survival prediction in men with cardiovascular disease: a 10-year follow-up study

Objective To determine whether the walking speed maintained during a 1 km treadmill test at moderate intensity predicts survival in patients with cardiovascular disease. Design Population-based prospective study. Setting Outpatient secondary prevention programme in Ferrara, Italy. Participants 1255 male stable cardiac patients, aged 25–85 years at baseline. Main outcome measures Walking speed maintained during a 1 km treadmill test, measured at baseline and mortality over a median follow-up of 8.2 years. Results Among 1255 patients, 141 died, for an average annual mortality of 1.4%. Of the variables considered, the strongest predictor of all-cause mortality was walking speed (95% CI 0.45 to 0.75, p<0.0001). Based on the average speed maintained during the test, participants were subdivided into quartiles and mortality risk adjusted for confounders was calculated. Compared to the slowest quartile (average walking speed 3.4 km/h), the relative mortality risk decreased for the second, third and fourth quartiles (average walking speed 5.5 km/h), with HRs of 0.73 (95% CI 0.46 to 1.18); 0.54 (95% CI 0.31 to 0.95) and 0.20 (95% CI 0.07 to 0.56), respectively (p for trend <0.0001). Receiver operating curve analysis showed an area under the curve of 0.71 (p<0.0001) and the highest Youden index (0.35) for a walking speed of 4.0 km/h. Conclusions The average speed maintained during a 1 km treadmill walking test is inversely related to survival in patients with cardiovascular disease and is a simple and useful tool for stratifying risk in patients undergoing secondary prevention and cardiac rehabilitation programmes.

Peak oxygen uptake prediction from a moderate, perceptually regulated, 1-km treadmill walk in male cardiac patients.

PURPOSE: To determine whether a moderate 1-km treadmill walking test (1KTWT) could be used to predict peak oxygen uptake ( O2peak) in patients with cardiovascular disease. METHODS: One hundred seventy-eight male patients, aged 38 to 83 years, completed a O2peak treadmill test and a 1KTWT using a self-regulated intensity of 11 to 13 of 20 on the Borg scale. Multivariable regression analysis was used to develop equations for predicting O2peak in a development group (n = 110), both for subjects prescribed and not prescribed a &bgr;-blocking agent (BB/NBB, 66/44). These equations were then applied to a cross-validation and reproducibility group (n = 68, BB/NBB, 37/31), who completed the protocol twice within 2 weeks. RESULTS: Analysis from 1KTWT in the development group showed that age, body mass index, walking speed, and heart rate were the most potent predictors of O2peak. Measured and predicted O2peak were not significantly different, and were strongly associated among both the NBB (r = 0.81, P < .0001) and BB (r = 0.69, P < .0001) groups, with a mean residual of approximately 1.0 mL·kg−1·min−1. When applied to the cross-validation and reproducibility group, the equations similarly yielded strong associations (r = 0.64, P < 0.001 and r = 0.71, P < 0.001 for the NBB and BB groups, respectively), with no significantly differences between measured and predicted O2peak. Mean test-retest differences for measured and predicted O2peak were between 0.1 and −0.5 mL·kg−1·min−1. CONCLUSIONS: Equations developed from the 1KTWT accurately predicted O2peak in patients with cardiovascular disease. The model may represent a valid, low cost, and simple tool for indirect estimations of cardiorespiratory fitness in an outpatient setting.

Home-centred physical fitness programme in morbidly obese individuals: a randomized controlled trial

Objective: To assess the effectiveness of domiciliary physical fitness programmes in obese individuals. Design: Nine-month randomized controlled trial. Setting: Home-based intervention with outpatient visits. Subjects: Morbidly obese subjects (body mass index (BMI) ≥30) aged 25—65 years suitable for physical activities at home. Intervention: At the end of a preliminary one-month in-hospital rehabilitation programme (baseline), 52 patients were randomly assigned either to a structured educational programme (intervention group) of daily incremental physical activity at home (walking and skeletal muscle resistance training, with booklets and written instructions) or to a programme of general advice (control group) regarding exercise and long-term fitness. Main measures: Both groups were evaluated at baseline and every three months for: (1) time, metabolic equivalents (METs), and heart rate reserve (HRR) during a standardized 2-km walking test (2kmWT); (2) anthropometric measures (body weight, BMI, abdominal and neck circumference); (3) the Polar Fitness Test index (PFTI), and (4) time to exhaustion while sustaining consecutive isoload extensions in the dominant leg (isoload LE). Time during 2kmWT was the study primary outcome. Results: Body weight, BMI and abdominal circumference improved significantly (P<0.05) over time in the intervention group. The cardiopulmonary fitness variables changed significantly (P<0.05) over time in both study groups. However, all variables improved in the intervention patients, while some worsened or remained stable in the controls. Thus, the mean group difference in changes was significant (P<0.05) for 2kmWT time (—77.4 seconds), HRR (11.7%), and PFTI (5.4 points). Conclusion: This structured domiciliary fitness programme is feasible and provides sustained anthropometric and physiological benefits in some morbidly obese individuals.

Association between VO2 peak estimated by a 1-km treadmill walk and mortality. A 10-year follow-up study in patients with cardiovascular disease

PURPOSE The aim of this study is to assess the association between peak oxygen uptake (VO2 peak), determined using a perceptually regulated 1-km walking test (1k-TWT), and all-cause mortality in cardiac patients. METHODS 1255 male patients, aged 25-85 years, completed a moderate 1k-TWT to estimate VO2 peak. Subjects were followed for all-cause mortality for up to 10 years. Cox proportional hazard models were employed to determine variables associated with mortality. Based on the estimated VO2 peak, the sample was subdivided into quartiles and mortality risks were calculated. To assess the discriminatory accuracy of the estimated VO2 peak for estimating survival, receiver-operating-characteristics curves were constructed. RESULTS During a median 8.2 year follow-up, a total of 141 deaths from any cause occurred, yielding an average annual mortality of 1.4%. The strongest predictor of all-cause mortality was the estimated VO2 peak (c-statistic 0.71, 95% confidence intervals: 0.69-0.74, P<0.0001). Survival decreased in a graded fashion from the highest estimated VO2 peak quartile to the lowest quartile. Compared to the lowest quartile, the hazard ratios (95% confidence intervals) for the second, third, and fourth quartiles were 0.77 (0.35-1.33), 0.43 (0.20-0.91), and 0.16 (0.05-0.54) respectively (P for trend <0.0001). An 89% reduction in mortality risk was observed among a subset of subjects in the fittest quartile who improved their estimated VO2 peak over the follow-up period relative to subjects in the least fit quartile who did not improve. CONCLUSION VO2 peak estimated by a novel 1k-TWT predicts survival in subjects with stable cardiovascular disease.

Improved walking speed is associated with lower hospitalisation rates in patients in an exercise-based secondary prevention programme

Objective To determine the relationship between walking speed (WS) maintained during a 1 km test and its improvement on hospitalisation in cardiac outpatients who were referred to an exercise-based secondary prevention programme. Methods Hospitalisation was assessed in 1791 patients 3 years after enrolment and related to the WS achieved during a 1 km walk at moderate intensity on a treadmill. Hospitalisation was also assessed during the fourth-to-sixth years as function of improvement in WS in 1111 participants who were re-evaluated 3 years after baseline. Results Three-year hospitalisation rate across tertiles of baseline WS was 50% for the slow walkers (2.7±0.6 km/hour), 41% for the moderate (4.1±0.3 km/hour) and 25% for the fast walkers (5.2±0.5 km/hour) (p for trend <0.0001), with adjusted HRs (95% CI) of 0.93 (0.74 to 1.17, p=0.53) for intermediate and 0.58 (0.43 to 0.78, p=0.0003) for fast. Every 1 km/hour increase in WS was associated with a 21% reduction in hospitalisation (p<0.0001). Hospitalisation from the fourth-to-sixth years was lower across tertiles of improved WS, with 44% for the low (0.2±0.4 km/hour), 34% for the intermediate (0.8±0.2 km/hour) and 30% for the high tertile (1.6±0.4 km/hour) (p for trend <0.0001). Adjusted HRs were 0.68 (p=0.002) for the intermediate and 0.58 (p<0.0001) for the high tertile. Every 1 km/hour increase in WS was associated with a 35% reduction in hospitalisation (p<0.0001). Conclusion Improvement in WS is associated with a significant, dose-dependent lower rate of all-cause hospitalisation in cardiac outpatients. WS is a simple, easily applied and clinically useful tool for cardiac patients undergoing secondary prevention.

A moderate 1-km treadmill walk predicts mortality in men with mid-range left ventricular dysfunction

The prevalence of heart failure considerably increased over the last three decades because of the aging population and the improved survival rate after acute cardiac events. Clinical and research programs more frequently are directed to patients with severely impaired functional capacity. Nevertheless, heart failure with mid-range left ventricular dysfunction (HFmrEF) has been recently defined as a distinct clinical entity. Cardiorespiratory fitness (CRF), usually best reflected by peak oxygen consumption (VO2peak), has been shown to be a powerful and independent prognostic marker in patients with heart failure. CRF has been linked to both cardiovascular and non-cardiovascular outcomes in ambulatory patients with heart failure. VO2peak is strongly related to walking capacity in older adults, and among heart failure patients. The walking speed maintained during a submaximal 1-km treadmill walk (1 k-TWT) has been demonstrated to be a valid and simple tool for VO2peak estimation, 12–14 and is inversely related to survival, and hospitalization, in outpatients with cardiovascular disease and preserved left ventricular ejection fraction (LVEF). We examine the association between VO2peak estimated by the 1 k-TWT and all-cause mortality in men with HFmrEF. We studied 209 medically stable male outpatients aged 65 10 years, with LVEF 40% 5%, referred to our exercise-based secondary prevention program. Each patient performed the moderate perceptually-regulated (11–13 on the 6–20 Borg scale) 1 k-TWT. Time to walk 1-km, mean and maximal heart rates during the walk, age, height, and weight were entered into the equations for VO2 peak estimation. Based on the VO2peak, the sample was subdivided into tertiles and mortality risks were calculated during a median follow up of 9.4 years. The local Ethics Committee approved the study protocol, and all patients gave written informed consent. Survival decreased in a graded fashion from the highest VO2peak tertile to the lowest tertile (p< 0.0001, Figure 1). During the follow-up period, 23, 11, and 3 all-cause deaths occurred among the lowest, intermediate, and highest VO2peak tertile respectively. Mortality rate was independent from traditional cardiovascular risk factors, including LVEF and clinical history. Compared with the lowest tertile (mean walking speed 2.8 km/h), the full-adjusted mortality risk decreased for the second (mean walking speed 3.8 km/h), and third tertile (mean walking speed 4.6 km/h), with hazard ratios of 0.64 (95% confidence interval (CI): 0.33–1.20, p1⁄4 0.18), and 0.26 (95% CI: 0.08–0.80, p1⁄4 0.02), respectively (p for trend< 0.0001). These results are similar to those obtained by other studies in which VO2peak was determined by maximal cardiopulmonary exercise testing. Consistent with previous studies, we observed a 24.5% reduction in all cause mortality associated with each 1-Metabolic equivalent (MET) increment in VO2peak (p1⁄4 0.04). In conclusion, our findings show that VO2peak estimated from a simple moderate 1 k-TWT predicts

Determining the best percent-predicted equation for estimated VO2 peak by a 1-km moderate perceptually-regulated treadmill walk to predict mortality in outpatients with cardiovascular disease

OBJECTIVES To determine the prognostic ability of established percent-predicted equations of peak oxygen consumption (%PRED) estimated by a moderate submaximal walking test in a large cohort of outpatients with cardiovascular disease (CVD). DESIGN Population-based prospective study. METHODS A total of 1442 male patients aged 25-85 years at baseline, underwent a moderate perceptually-regulated (11-13 on the 6-20 Borg scale) treadmill walk (1k-TWT) for peak oxygen consumption estimation (VO2 peak). %PRED was derived from ACSM, Ades et al, Morris et al, and the Wasserman/Hansen equations, and their prognostic performance was assessed. Overall mortality was the end point. Participants were divided into quartiles of %PRED, and mortality risk was estimated using a Cox regression model. RESULTS During a median 8.2year follow-up, 167 all-cause deaths occurred. The Wasserman/Hansen equation provided the highest prognostic value. Mortality rate was lower across increasing quartiles of %PRED. Compared to the first quartile, after adjustment for confounders, the mortality risk decreased for the second, third, and fourth quartiles, with HRs of 0.75 (95% CI 0.44-1.29, p=0.29), 0.67 (95% CI 0.38-1.18, p=0.17), and 0.37 (95% CI 0.10-0.78, p=0.009), respectively (p for trend <0.0001). Each 1% increase in %PRED conferred a 4% improvement in survival. CONCLUSIONS The percent-predicted VO2 peak determined by Wasserman/Hansen equations applied to the 1k-TWT is inversely and significantly related to survival in cardiac outpatients. The 1k-TWT is a simple and useful tool for stratifying mortality risk in patients participating in secondary prevention programs.

Walking and hypertension: greater reductions in subjects with higher baseline systolic blood pressure following six months of guided walking

Background The aim of the study was to assess the effects of walking on the blood pressure in sedentary adults with differing degrees of systolic blood pressure (SBP). Methods A total of 529 subjects with SBP above 120 mmHg were enrolled. Blood pressure, body weight, body mass index, waist circumference and walking speed were determined at enrolment and after six months. Walking sessions were supervised by exercise physiologists. Results The weekly walking time of the subjects completing the project was uniform and reached 300 minutes by the second month. 56% of participants completed the 6 months intervention (182 women 59.6 ± 9.0 years, and 114 men, 65.4 ± 8.6 years) 27 had a baseline SBP >160 mm Hg, 35 between 150–159, 70 between 140–149, 89 between 130–139 and 75 between 120–129 mmHg. Following six months of supervised walking, SBP was significantly reduced in all subgroups (p < 0.001), with the greatest reduction (−21.3 mmHg) occurring in subjects with baseline SBP >160 and the smallest reduction (−2.6 mmHg) occurring in subjects with baseline SBP of 120–129 mmHg. Diastolic blood pressure, body weight, body mass index and waist circumference were also significantly reduced following the walking intervention (p < 0.001). These reductions were nearly identical within the various groups. Discussion In a large group of sedentary adults with varying degrees of SBP, 6 months of supervised walking elicited a marked reduction in systolic blood pressure with the largest reductions in pressure occurring in individuals with higher baseline SBP.

Moderate walking speed predicts hospitalisation in hypertensive patients with cardiovascular disease

Hypertension (HTN) is a leading risk factor for developing cardiovascular disease (CVD), and carries a major global burden of disease. Blood pressure (BP) and CVD are strongly associated, with even small increments in BP leading to an increased risk of CVD. The prevalence of HTN is influenced by several lifestyle factors, including smoking, diet, body mass and insufficient physical activity. On the other hand, it is well known that healthy lifestyle changes, including increased physical activity, contribute significantly to better BP control. Epidemiological studies have demonstrated an inverse relationship between physical activity, cardiorespiratory fitness (CRF) and HTN. In addition, a considerable number of studies have shown significant lowering of BP through regular aerobic exercise of moderate intensity in patients with HTN. Even though higher CRF has been associated with lower risk of future events among people with HTN, hypertensive patients are less physically active than normotensive people. The gold standard for the assessment of CRF is the direct determination of the peak oxygen uptake (VO2peak) by measuring gas exchange during incremental and maximal exercise testing. The assessment of VO2peak is recommended for assessing CVD severity, predicting prognosis and evaluating the efficacy of cardiac rehabilitation/secondary prevention programmes. When added to common risk factors, including systolic blood pressure, VO2peak significantly improves the estimation of both shortand long-term risk for CVD mortality. However, practical, financial and time constraints limit the direct determination of VO2peak in many clinical settings. VO2peak has been demonstrated to be strongly associated with walking capacity in well-functioning older adults and among heart failure patients. Walking is the most common physical activity among adults, and is the preferred mode of exercise testing. A simple, submaximal 1-km treadmill walking test (1 k-TWT) has been validated for the estimation of VO2peak among stable outpatients with CVD, with and without preserved left ventricular ejection fraction. In addition, walking speed is a well-known indicator of health and function in aging and disease. Whether higher walking speed attenuates the risk of hospitalisation in adults with HTN is less known. Thus, we aimed to examine the association between walking speed and long-term all-cause hospitalisation in patients with HTN and CVD. Hospitalisation was assessed in 1078 patients (male/ female 867/211, age 64 10 years) with HTN and CVD (&85% with coronary heart disease) three years after enrolment in an exercise-based secondary prevention programme. All patients completed a baseline health examination and a 1-km treadmill walk at a moderate intensity, perceptually regulated at 11–13/20 on the Borg Scale. All-cause hospitalisation was assessed as function of the walking speed during the 1 k-TWT. At baseline subjects were subdivided into three groups based on walking speed as follows: SLOW (2.6 0.5 km/h, n1⁄4 359), INTERMEDIATE (3.9 0.3 km/h, n1⁄4 362) and FAST (5.1 0.5 km/h, n1⁄4 357). During the following three years all-cause