James M. Rippe

Chronic psychological effects of exercise and exercise plus cognitive strategies.

Psychological changes associated with 16-wk moderate and low intensity exercise training programs, two of which possessed a cognitive component, were evaluated. Subjects were healthy, sedentary adults, 69 women (mean age = 54.8 +/- 8.3 yr) and 66 men (mean age = 50.6 +/- 8.0 yr). Participants were randomly assigned to a control group (C), moderate intensity walking group (MW), low intensity walking group (LW), low intensity walking plus relaxation response group (LWR), or mindful exercise (ME) group-a Tai Chi type program. Women in the ME group experienced reductions in mood disturbance (tension, P < 0.01; depression, P < 0.05; anger, P < 0.008; confusion, P < 0.02; and total mood disturbance, P < 0.006) and an improvement in general mood (P < 0.04). Women in the MW group noted greater satisfaction with physical attributes (body cathexis, P < 0.03), and men in MW reported increased positive affect (P < 0.006). No other differences were observed between groups on measures of mood, self-esteem, personality, or life satisfaction. Equivocal support is provided for the hypothesis that exercise plus cognitive strategy training programs are more effective than exercise programs lacking a structured cognitive component in promoting psychological benefits.

Development of a single-stage submaximal treadmill walking test

An equation was developed to estimate maximal oxygen uptake (VO2max, ml.kg-1.min-1) based on a single submaximal stage of a treadmill walking test. Subjects (67 males, 72 females) aged 20-59 yr completed 4-min stages at 0, 5, and 10% grades walking at a constant speed (2.0-4.5 mph) and then performed a VO2max test. Heart rate and respiratory gas exchange variables were measured during the test. Multiple regression analysis (N = 117) to estimate VO2max from the 4-min stage at 5% grade yielded the following model (R2 = 0.86; SEE = 4.85 ml.kg-1.min-1): VO2max = 15.1 + 21.8*SPEED (mph) -0.327*HEART RATE (bpm) -0.263*SPEED*AGE (yr) + 0.00504*HEART RATE*AGE + 5.98*GENDER (0 = Female; 1 = Male). The constant and all coefficients were highly significant (P less than 0.01). To assess the accuracy of the model in a cross-validation group (N = 22), an estimated VO2max value was obtained using the above model. Estimated VO2max then was regressed on observed VO2max yielding the following equation (R2 = 0.92): ESTIMATED VO2max = 0.15 + 1.03*OBSERVED VO2max. The intercept and slope of this equation were not significantly different from 0 and 1, respectively. For 90.9% of the subjects in the cross-validation group, residual scores were within the range of +/- 5 ml.kg-1.min-1. In conclusion, this submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating VO2max.

Nonexercise regression models to estimate peak oxygen consumption.

The purpose of this study was to develop a VO2peak prediction model derived from nonexercise (N-EX) based predictors. VO2peak was measured using a walking treadmill protocol with 229 females and 210 males between 20 and 79 yr of age (mean +/- SD: 38.62 +/- 10.36 ml.kg-1.min-1). Subjects were randomly divided into validation (V) (85% of total; N = 374) and cross-validation (CV) (15% of total; N = 65) groups. The V group was used to validate generalized and gender-specific models using stepwise multiple regression procedures with gender, age and age2, percent body fat, and a physical activity code (AC). The generalized ml.kg-1.min-1 (R2 = 0.77, SEE = 4.90 ml.kg-1.min-1, SEE% = 12.7%) and gender-specific (females: R2 = 0.72, SEE = 4.64 ml.kg-1.min-1; males: R2 = 0.72, SEE = 5.02 ml.kg-1.min-1) models were highly accurate relative to N-EX and exercise based models in the literature. Cross-validation procedures were used to evaluate model stability. The generalized model was stable across the total CV group and various CV subsamples (by gender, decade-wide age groups, and AC groups), but not across groups similar in VO2peak. These results suggest that N-EX models can be valid predictors of VO2peak for heterogenous samples.

Obesity and cardiovascular disease risk: research update.

The obesity epidemic has reached unprecedented proportions in Western society. Evidence continues to accumulate that obesity is associated with significant morbidity and mortality and in particular that it is an independent risk factor for cardiovascular disease (CVD). The association of obesity with CVD and its risk factors, including hypertension, dyslipidemia, glucose intolerance, and impaired hemostasis is becoming more clearly understood. An increasing body of data indicates that risk factors tend to cluster in obese individuals and may act synergistically to increase these people’s risk for CVD. Individuals with disproportionate visceral adiposity are at significantly greater risk for CVD. Adult weight gain also underlies the development of many risk factors and augments the risk of CVD. Physicians can play a vital and active role in the prevention and treatment of obesity and overweight and thereby reduce patients’ CVD risk.

Walking for Health and Fitness

Recent studies have linked regular physical activity with reduced likelihood of developing coronary heart disease. Even low- and moderate-intensity exercise such as walking, when carried out consistently, is associated with important cardiovascular health benefits. Walking has also been shown to reduce anxiety and tension and aid in weight loss. Regular walking may help improve cholesterol profile, help control hypertension, and slow the process of osteoporosis. Recent physiological studies have demonstrated that brisk walking provides strenuous enough exercise for cardiovascular training in most adults. A recently developed submaximal 1-mile walk test provides a simple and accurate means for estimating aerobic capacity and guiding exercise prescription. These new insights and tools will assist the clinician in the prescription of safe and effective walking programs.

Sucrose, High-Fructose Corn Syrup, and Fructose, Their Metabolism and Potential Health Effects: What Do We Really Know?

Both controversy and confusion exist concerning fructose, sucrose, and high-fructose corn syrup (HFCS) with respect to their metabolism and health effects. These concerns have often been fueled by speculation based on limited data or animal studies. In retrospect, recent controversies arose when a scientific commentary was published suggesting a possible unique link between HFCS consumption and obesity. Since then, a broad scientific consensus has emerged that there are no metabolic or endocrine response differences between HFCS and sucrose related to obesity or any other adverse health outcome. This equivalence is not surprising given that both of these sugars contain approximately equal amounts of fructose and glucose, contain the same number of calories, possess the same level of sweetness, and are absorbed identically through the gastrointestinal tract. Research comparing pure fructose with pure glucose, although interesting from a scientific point of view, has limited application to human nutrition given that neither is consumed to an appreciable degree in isolation in the human diet. Whether there is a link between fructose, HFCS, or sucrose and increased risk of heart disease, metabolic syndrome, or fatty infiltration of the liver or muscle remains in dispute with different studies using different methodologies arriving at different conclusions. Further randomized clinical trials are needed to resolve many of these issues. The purpose of this review is to summarize current knowledge about the metabolism, endocrine responses, and potential health effects of sucrose, HFCS, and fructose.

High-fructose corn syrup, energy intake, and appetite regulation

High-fructose corn syrup (HFCS) has been implicated in excess weight gain through mechanisms seen in some acute feeding studies and by virtue of its abundance in the food supply during years of increasing obesity. Compared with pure glucose, fructose is thought to be associated with insufficient secretion of insulin and leptin and suppression of ghrelin. However, when HFCS is compared with sucrose, the more commonly consumed sweetener, such differences are not apparent, and appetite and energy intake do not differ in the short-term. Longer-term studies on connections between HFCS, potential mechanisms, and body weight have not been conducted. The main objective of this review was to examine collective data on associations between consumption of HFCS and energy balance, with particular focus on energy intake and its regulation.

The Effect of High-Fructose Corn Syrup Consumption on Triglycerides and Uric Acid

Rates of overweight and obesity have been on a steady rise for decades, and the problems society faces from this and associated metabolic diseases are many. As a result, the need to understand the contributing factors is great. A very compelling case can be made that excess sugar consumption has played a significant role. In addition, fructose, as a component of the vast majority of caloric sweeteners, is seen to be particularly insidious. Evidence shows that fructose bypasses many of the bodys satiating signals, thus potentially promoting overconsumption of energy, weight gain, and the development on insulin resistance. It has also been shown to increase uric acid levels, which in turn promotes many of the abnormalities seen in the metabolic syndrome including hypertriglyceridemia. However, the main source of fructose in the diet is high-fructose corn syrup (HFCS), an artificially manufactured disaccharide that is only 55% fructose. This review highlights the fact that limited data are available about the metabolic effects of HFCS compared with other caloric sweeteners. The data suggest that HFCS yields similar metabolic responses to other caloric sweeteners such as sucrose.

Consumption of sucrose and high-fructose corn syrup does not increase liver fat or ectopic fat deposition in muscles

It has been postulated that fructose-induced triglyceride synthesis is augmented when accompanied by glucose. Chronic elevations could lead to excess fat accumulation in the liver and ectopic fat deposition in muscles, which in turn could contribute to the induction of abnormalities in glucose homeostasis, insulin resistance, and the subsequent development of type 2 diabetes. Our objective was to evaluate the effect of the addition of commonly consumed fructose- and (or) glucose-containing sugars in the usual diet on liver fat content and intramuscular adipose tissue. For 10 weeks, 64 individuals (mean age, 42.16 ± 11.66 years) consumed low-fat milk sweetened with either high-fructose corn syrup (HFCS) or sucrose; the added sugar matched consumption levels of fructose in the 25th, 50th, and 90th percentiles of the population. The fat content of the liver was measured with unenhanced computed tomography imaging, and the fat content of muscle was assessed with magnetic resonance imaging. When the 6 HFCS and sucrose groups were averaged, there was no change over the course of 10 weeks in the fat content of the liver (13.32% ± 10.49% vs. 13.21% ± 10.75%; p > 0.05), vastus lateralis muscle (3.07 ± 0.74 g per 100 mL vs. 3.15 ± 0.84 g per 100 mL; p > 0.05), or gluteus maximus muscle (4.08 ± 1.50 g per 100 mL vs. 4.24 ± 1.42 g per 100 mL; p > 0.05). Group assignment did not affect the result (interaction > 0.05). These data suggest that when fructose is consumed as part of a typical diet in normally consumed sweeteners, such as sucrose or HFCS, ectopic fat storage in the liver or muscles is not promoted.

Weight loss and total lipid profile changes in overweight women consuming beef or chicken as the primary protein source

OBJECTIVE Conflicting recommendations are prevalent regarding the appropriateness of red meat versus white meat consumption for individuals aiming to reduce body weight and cardiovascular disease risk. METHODS We examined changes in body weight and lipid profiles in a 12-wk, randomized, controlled trial, in which overweight women followed a hypocaloric diet with lean beef or chicken as the primary protein source, while participating in a fitness walking program. Sedentary non-smoking females (n = 61), age 43.4 +/- 7.8 years, with body mass indexes of 32.1 +/- 3.4 kg/m(2) (means +/- standard deviation), followed calculated-deficit diets (-500 kcal daily) and were randomly assigned to the beef-consumption or chicken-consumption dietary group, while following a fitness walking program. Body weight, body composition (by hydrodensitometry), and blood lipid profiles were measured at baseline and 12 wk. RESULTS Weight loss was significant within (P < 0.05) but similar between (P > 0.05) the beef-consumption (5.6 +/- 0.6 kg, mean +/- standard error) and the chicken-consumption (6.0 +/- 0.5 kg) groups. Both groups showed significant reductions in body fat percentage (P < 0.05) and total (P < 0.05) and low-density lipoprotein (P < 0.05) cholesterol, with no significant differences between groups. High-density lipoprotein cholesterol did not change significantly in either group. CONCLUSIONS These findings demonstrated that weight loss and improved lipid profile can be accomplished through diet and exercise, whether the dietary protein source is lean beef or chicken.