Steven P. Hooker

Sedentary Behaviors Increase Risk of Cardiovascular Disease Mortality in Men

PURPOSE The purpose of this study was to examine the relationship between two sedentary behaviors (riding in a car and watching TV) and cardiovascular disease (CVD) mortality in men in the Aerobics Center Longitudinal Study. METHODS Participants were 7744 men (20-89 yr) initially free of CVD who returned a mail-back survey during 1982. Time spent watching TV and time spent riding in a car were reported. Mortality data were ascertained through the National Death Index until December 31, 2003. Cox regression analysis quantified the association between sedentary behaviors (hours per week watching TV, hours per week riding in a car, and total hours per week in these two behaviors) and CVD mortality rates. RESULTS Three hundred and seventy-seven CVD deaths occurred during 21 yr of follow-up. After age adjustment, time riding in a car and combined time spent in these two sedentary behaviors were positively (P(trend) < 0.001) associated with CVD death. Men who reported >10 h x wk(-1) riding in a car or >23 h x wk(-1) of combined sedentary behavior had 82% and 64% greater risk of dying from CVD than those who reported <4 or <11 h x wk(-1), respectively. The pattern of the association did not materially change after multivariate adjustment. Regardless of the amount of sedentary activity reported by these men, being older, having normal weight, being normotensive, and being physically active were associated with a reduced risk of CVD death. CONCLUSION In men, riding in a car and combined time spent in these two sedentary behaviors were significant CVD mortality predictors. In addition, high levels of physical activity were related to notably lower rates of CVD death even in the presence of high levels of sedentary behavior. Health promotion efforts targeting physically inactive men should emphasize both reducing sedentary activity and increasing regular physical activity for optimal cardiovascular health.

Effects of low- and moderate-intensity training in spinal cord-injured persons.

This study examined the applicability of exercise prescription guidelines established for the able-bodied to spinal cord-injured (SCI) persons. Two SCI groups performed wheelchair ergometry (WCE) 20 min three times per week for 8 wk. Low-intensity (LI, N = 6) and moderate-intensity (MI, N = 5) groups trained at 50-60% and 70-80% maximal heart rate reserve (HRR), respectively. The subjects completed an incremental discontinuous maximal WCE test to exhaustion pre- and post-training. A submaximal WCE test consisting of 4-min exercise stages at power outputs of 5, 10, and 15 W was also performed pre- and post-training. Blood samples were collected before and after training and analyzed for total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C). The TC/HDL-C ratio was calculated. Both groups exhibited no significant changes (P greater than 0.10) in VO2max, HRmax, POmax, lactate (La)max, and VO2 at 4 mmol [La]. No pre- to post-training differences were recorded in the LI group for submaximal VO2, HR, VE, La, and ratings of perceived exertion (RPE). The MI group had significantly lower (P less than or equal to 0.10) post-training submaximal HR, La, and RPE and no changes in VO2 or VE. Blood lipid levels remained unaltered in the LI group, while the MI group exhibited significant increases in HDL-C and decreases in TG, LDL-C, and the TC/HDL-C ratio. The maximal test data revealed that 8 wk of LI and MI wheelchair ergometry training did not improve VO2max in SCI persons.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the Built Environment on Physical Activity of Adults Living in Rural Settings

Objective. To conduct a systematic review of the literature to examine the influence of the built environment (BE) on the physical activity (PA) of adults in rural settings. Data Source. Key word searches of Academic Search Premier, PubMed, CINAHL, Web of Science, and Sport Discus were conducted. Study Inclusion and Exclusion Criteria. Studies published prior to June 2008 were included if they assessed one or more elements of the BE, examined relationships between the BE and PA, and focused on rural locales. Studies only reporting descriptive statistics or assessing the reliability of measures were excluded. Data Extraction. Objective(s), sample size, sampling technique, geographic location, and definition of rural were extracted from each study. Methods of assessment and outcomes were extracted from the quantitative literature, and overarching themes were identified from the qualitative literature. Data Synthesis. Key characteristics and findings from the data are summarized in Tables 1 through 3. Results. Twenty studies met inclusion and exclusion criteria. Positive associations were found among pleasant aesthetics, trails, safety/crime, parks, and walkable destinations. Conclusions. Research in this area is limited. Associations among elements of the BE and PA among adults appear to differ between rural and urban areas. Considerations for future studies include identifying parameters used to define rural, longitudinal research, and more diverse geographic sampling. Development and refinement of BE assessment tools specific to rural locations are also warranted.

Musculoskeletal responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise training.

This study was conducted to evaluate a newly designed functional neuromuscular stimulation (FNS)-induced knee extension (KE) exercise system that incorporates the most desired features of previously described systems by determining the musculoskeletal responses of spinal cord injured (SCI) individuals to training. A specially designed chair and electrical stimulator were fabricated for FNS-induced KE resistance exercise. Surface electrodes were placed over motor points of the quadriceps muscles, and KE was alternated between legs at an average rate of 6 KE/min/leg. KE testing protocols were developed for pre- and post-training evaluations of performance, and 12 SCI subjects exercise-trained up to three times per week for 36 sessions using a progressive resistance load at ankle level. Pre- and post-training evaluation data were statistically compared using a 0.05 level for significance. Quadriceps muscle performance (strength x repetitions) improved for both legs in all subjects as indicated by significant increases in load resistance and repetitions over the 36-session training period (right leg mean = 1156.0 versus 1624.8 kg.reps, left leg mean = 1127.3 versus 1721.1 kg.reps). In addition, knee range of motion significantly increased (right leg mean = 134 versus 146 degrees, left leg mean = 133 versus 144 degrees). Thigh skinfold, thigh girth, body weight and bone density were not significantly changed. The lack of decrease in bone density in some subjects suggests that the training may retard the rate of bone loss which typically occurs with SCI. No injuries or problems were encountered during testing and training.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic syndrome and risk of cancer mortality in men

BACKGROUND Metabolic syndrome (MetS) has been linked with an increased risk of developing cancer; however, the association between MetS and cancer mortality remains less clear. Little research has focused on pre-cancer risk factors that may affect the outcome of treatment. The purpose of this study was to examine the association between MetS and all-cancer mortality in men. METHODS The participants included 33,230 men aged 20-88 years who were enrolled in the Aerobics Centre Longitudinal Study and who were free of known cancer at the baseline. RESULTS At baseline 28% of all the participants had MetS. During an average of 14 years follow-up, there were a total of 685 deaths due to cancer. MetS at baseline was associated with a 56% greater age-adjusted risk in cancer mortality. CONCLUSION These data show that MetS is associated with an increased risk of all-cause cancer mortality in men. Based on these findings, it is evident that successful interventions should be identified to attenuate the negative effects of MetS.

Alcohol Consumption and Risk of All-Cause and Cardiovascular Disease Mortality in Men

This study examined the association between consumption of alcoholic beverages and all-cause and cardiovascular disease (CVD) mortality in a cohort of men (n = 31,367). In the Cox proportional hazards model adjusted for age, year of examination, body mass index (BMI), smoking, family history of CVD, and aerobic fitness, there were no significant differences in risk of all-cause mortality across alcohol intake groups. Risk of CVD mortality was reduced 29% in quartile 1 (HR = 0.71, 95% confidence interval (CI): 0.53, 0.95) and 25% in quartile 2 (HR = 0.75, 95% CI: 0.58, 0.98). The amount of alcohol consumed to achieve this risk reduction was <6 drinks/week; less than the amount currently recommended. The addition of other potential confounders and effect modifiers including blood pressure, insulin sensitivity, lipid levels, and psychological variables did not affect the magnitude of association. Future research is needed to validate the current public health recommendations for alcohol consumption.

Cardiorespiratory Fitness as a Predictor of Fatal and Nonfatal Stroke in Asymptomatic Women and Men

Background and Purpose— Prospective data on the association between cardiorespiratory fitness (CRF) and stroke are largely limited to studies in men or do not separately examine risks for fatal and nonfatal stroke. This study examined the association between CRF and fatal and nonfatal stroke in a large cohort of asymptomatic women and men. Methods— A total of 46 405 men and 15 282 women without known myocardial infarction or stroke at baseline completed a maximal treadmill exercise test between 1970 and 2001. CRF was grouped as quartiles of the sex-specific distribution of maximal metabolic equivalents achieved. Mortality follow-up was through December 31, 2003, using the National Death Index. Nonfatal stroke, defined as physician-diagnosed stroke, was ascertained from surveys during 1982 to 2004. Cox regression models quantified the pattern and magnitude of association between CRF and stroke. Results— There were 692 strokes during 813 944 man-years of exposure and 171 strokes during 248 902 woman-years of exposure. Significant inverse associations between CRF and age-adjusted fatal, nonfatal, and total stroke rates were observed for women and men (Ptrend≤0.05 each). After adjusting for several cardiovascular disease risk factors, the inverse association between CRF and each stroke outcome remained significant (Ptrend<0.05 each) in men. In women, the multivariable-adjusted relationship between CRF and nonfatal and total stroke remained significant (Ptrend≤0.01 each), but not between CRF and fatal stroke (Ptrend=0.18). A CRF threshold of 7 to 8 maximal metabolic equivalents was associated with a substantially reduced rate of total stroke in both men and women. Conclusions— These findings suggest that CRF is an independent determinant of stroke incidence in initially asymptomatic and cardiovascular disease-free adults, and the strength and pattern of the association is similar for men and women.

Oxygen uptake and heart rate relationship in persons with spinal cord injury

The percent (%) peak oxygen uptake (VO2) and % peak heart rate (HR) relationships were determined in 13 persons with high (T1-T6) and 14 persons with low lesion (T7-T12) spinal cord injured paraplegia (SCI PARA) and 15 nonimpaired subjects during graded arm crank (AC) tests to exhaustion. Subjects were instructed to maintain a target cadence of 60 rpm on a modified electronically braked leg cycle ergometer. After 3 min of unloaded cranking, power output (PO) was increased by 8-16 W.min-1. VO2 and HR were determined via open-circuit spirometry and 12-lead ECG, respectively. Absolute HR and VO2 values for each PO were converted to % peak HR and % peak VO2 values. Linear regression slopes describing individual % peak HR and % peak VO2 relationships were calculated and compared between groups with one-way ANOVA. No significant differences (P > 0.05) were noted between the mean (+/- SD) regression slopes for persons with high lesion SCI PARA (1.48 +/- 0.21), persons with low lesion SCI PARA (1.48 +/- 0.26), and nonimpaired subjects (1.53 +/- 0.29). Regression equations derived using all data points within each group were as follows: High lesion SCI PARA: y = 1.3x-37.0, R = 0.85 Low lesion SCI PARA: y = 1.23x-30.9, R = 0.88 Nonimpaired subjects: y = 1.41x-46.2, R = 0.95 (y = % peak VO2, x = % peak HR). These equations are similar to those previously reported for nonimpaired men and women and cardiac patients during AC and leg cycle ergometry.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic responses of paraplegics and quadriplegics to passive and active leg cycle ergometry.

The purposes of this study were three-fold: (a) to determine acute physiologic responses of spinal cord injured (SCI) subjects to peak levels of leg cycle ergometry utilizing functional neuromuscular stimulation (FNS) of paralyzed leg muscles, (b) to determine the relative contributions of passive and active components of FNS cycling to the peak physiologic responses, and (c) to compare these physiologic responses between persons who have quadriplegia and those who have paraplegia. Thirty SCI subjects (17 quadriplegics and 13 paraplegics) performed a discontinuous graded FNS exercise test from rest to fatigue on an ERGYS 1 ergometer. Steady-state physiologic responses were determined by open-circuit spirometry, impedance cardiography with ECG, and auscultation. In the combined statistics of both groups, it was noted that peak FNS cycling significantly increased (from rest levels) mean oxygen uptake by 255%, arteriovenous O2 difference VO2 and VE, Q and a-vO2 and VCO by 69%, and stroke volume by 45%, while total peripheral vascular resistance decreased by 43%. Mean peak power output for paraplegics (15 W) was significantly higher than for quadriplegics (9 W), eliciting higher peak levels of pulmonary ventilation and sympathetically mediated hemodynamic responses such as cardiac output, heart rate, and systolic and diastolic arterial blood pressure. Passive cycling without FNS produced no statistically significant increases in physiologic responses above the resting level in either group.

Metabolic and hemodynamic responses to concurrent voluntary arm crank and electrical stimulation leg cycle exercise in quadriplegics

This study determined the metabolic and hemodynamic responses in eight spinal cord injured (SCI) quadriplegics (C5-C8/T1) performing subpeak arm crank exercise (ACE) alone, subpeak functional electrical stimulation leg cycle exercise (FES-LCE) alone, and subpeak FES-LCE concurrent with subpeak ACE (hybrid exercise). Subjects completed 10 minutes of each exercise mode during which steady-state oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), arteriovenous oxygen difference (a-v O2 diff), and total peripheral resistance (TPR) were determined. Although mean VO2 for both ACE alone and FES-LCE alone was matched at 0.66 l/mi, individualized power outputs ranged from 0-30 W (mean = 19.4 +/- 1.3) and 0-12.2 W (mean = 2.3 +/- 0.6), respectively. Hybrid exercise elicited significantly higher VO2 (by 54 percent), VE (by 39-53 percent), HR (by 19-33 percent), and CO (by 33-47 percent), and significantly lower TPR (by 21-34 percent) than ACE or FES-LCE performed alone (P less than or equal to 0.05). Stroke volume was similar between hybrid exercise and FES-LCE alone, and these two exercise modes evoked a significantly higher SV (by 41-56 percent) than during ACE alone. These data clearly demonstrate that hybrid exercise creates a higher aerobic metabolic demand and cardiac-volume load in SCI quadriplegics than either subpeak levels of ACE or FES-LCE performed separately. Therefore, hybrid exercise may provide more advantageous central cardiovascular training effects in quadriplegics than either ACE or FES-LCE alone.