Jason R. Jaggers

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.

The acute effects of dynamic and ballistic stretching on vertical jump height, force, and power

Jaggers, JR, Swank, AM, Frost, KL, and Lee, CD. The acute effects of dynamic and ballistic stretching on vertical jump height, force, and power. J Strength Cond Res 22(6): 1844-1849, 2008- Stretching before performance is a common practice among athletes in hopes of increasing performance and reducing the risk of injury. However, cumulative results indicate a negative impact of static stretching and proprioceptive neuromuscular facilitation (PNF) on performance; thus, there is a need for evaluating other stretching strategies for effective warm-up. The purpose of this study was to compare the differences between two sets of ballistic stretching and two sets of a dynamic stretching routine on vertical jump performance. Twenty healthy male and female college students between the ages of 22 and 34 (24.8 ± 3 years) volunteered to participate in this study. All subjects completed three individual testing sessions on three nonconsecutive days. On each day, the subjects completed one of three treatments (no stretch, ballistic stretch, and dynamic stretch). Intraclass reliability was determined using the data obtained from each subject. A paired samples t-test revealed no significant difference in jump height, force, or power when comparing no stretch with ballistic stretch. A significant difference was found on jump power when comparing no stretch with dynamic stretch, but no significant difference was found for jump height or force. Statistics showed a very high reliability when measuring jump height, force, and power using the Kistler Quattro Jump force plate. It seems that neither dynamic stretching nor ballistic stretching will result in an increase in vertical jump height or force. However, dynamic stretching elicited gains in jump power poststretch.

The Energy Balance Study: The Design and Baseline Results for a Longitudinal Study of Energy Balance

Purpose: The Energy Balance Study (EBS) was a comprehensive study designed to determine over a period of 12 months the associations of caloric intake and energy expenditure on changes in body weight and composition in a population of healthy men and women. Method: EBS recruited men and women aged 21 to 35 years with a body mass index between 20 and 35 kg/m2. Measurements of energy intake and multiple objective measures of energy expenditure, as well as other physiological, anthropomorphic and psychosocial measurements, were made quarterly. Resting metabolic rate and blood chemistry were measured at baseline, 6 and 12 months. Results: Four hundred and thirty (218 women and 212 men) completed all baseline measurements. There were statistically significant differences by sex uncovered for most anthropomorphic, physiological and behavioral variables. Only percent of kcals from fat and alcohol intake, as well as energy expenditure in light activity and very vigorous activity were not different. Self-reported weight change (mean ± SD) over the previous year were 0.92 ± 5.24 kg for women and − 1.32 ± 6.1 kg for men. Resting metabolic rate averages by sex were 2.88 ± 0.35 ml/kg/min for women and 3.05 ± 0.33 ml/kg/min for men. Conclusion: Results from EBS will inform our understanding of the impact of energy balance components as they relate to changes in body weight and composition. Initial findings suggest a satisfactory distribution of weight change to allow for robust statistical analyses. Resting metabolic rates well below the standard estimate suggest that the evaluation of the components of total energy expenditure will be impactful for our understanding of the roles of energy intake and expenditure on changes in energy utilization and storage.

Prehabilitation before knee arthroplasty increases postsurgical function: a case study.

Conditioning the body to undergo physical stress such as joint arthroplasty has been termed prehabilitation. This case study examined the effect of a 4-week prehabilitation intervention on functional outcomes after total knee arthroplasty (TKA). Two female subjects completed baseline strength and functional assessments before TKA. Subjects were randomized to either a 4-week prehabilitation intervention (ES) aimed at increasing strength and range of motion or a usual care condition (CS). After 4 weeks of training, subjects were reassessed and underwent TKA. Subjects completed a final assessment 12 weeks after TKA. Functional outcomes included 6-minute walk, number of times up from a chair in 30 seconds, proprioception, and self-reported function and pain using the Western Ontario and McMaster Universities Osteoarthritis Index. The data suggest that 4 weeks of prehabilitation had a positive effect on functional task performance and knee proprioception before surgery. After surgery, the ES continued to exhibit higher levels of functioning and less pain compared with the CS. Prehabilitation before TKA may contribute to improved recovery after surgery.

Impact of Aerobic and Resistance Exercise on the Health of HIV-Infected Persons

Individuals infected with HIV experience numerous comorbidities caused by the disease progression and medications, lack of (or inability to perform) physical activity, malnutrition, or a combination of these causes. Common symptoms include loss of muscle mass, fatigue, lypodystrophy, lypoatrophy, and decreases in strength, functional capacity, and overall quality of life. Studies have shown that exercise is a potential treatment of many of these symptoms. Research suggests that exercise may produce beneficial physiological changes in the HIV-infected population such as improved body composition and increases in both strength and endurance. In addition, psychological conditions such as depression and anxiety have been shown to be positively affected by exercise. The purpose of this review is to examine the literature regarding effects of aerobic, resistance, and combined aerobic and resistance exercise training on HIV-infected individuals.

Aerobic and resistance training improves mood state among adults living with HIV.

The purpose of this investigation was to examine the effects of combined aerobic and resistance exercise training among self-reported mood disturbances, perceived stress, frequency of self-reported symptoms, and symptom distress in a sample of HIV+ adults. For this purpose, 49 participants were randomly assigned into an exercise (EX) or control (CON) group. Those in the EX group completed 50 min of supervised aerobic and resistance training at a moderate intensity twice a week for 6 weeks. The CON group reported to the university and engaged in sedentary activities. Data were collected at baseline before randomization and 6 weeks post intervention. Measures included the symptom distress scale (SDS), perceived stress scale (PSS), profile of mood states (POMS) total score, and the POMS sub-scale for depression and fatigue. A 2 way ANOVA was used to compare between and within group interactions. The EX group showed a significant decrease in reported depression scores (p=0.03) and total POMS (p=0.003). The CON group reported no change in POMS or SDS, but showed a significant increase in PSS. These findings indicate that combination aerobic and resistance training completed at a moderate intensity at least twice a week provides additional psychological benefits independent of disease status and related symptoms.

Associations Between Physical Activity and Sedentary Time on Components of Metabolic Syndrome Among Adults with HIV

Recent data show that people living with HIV/AIDS (PLWHA) are at a greater risk of cardiovascular disease (CVD), which could possibly be explained by an increased prevalence of metabolic syndrome (MetSyn) due to the known toxicities associated with antiretroviral therapy (ART). The purpose of this study is to examine the relationships between physical activity (PA) and components of MetSyn in a sample of PLWHA taking ART. A total of 31 males and 32 females living with HIV and currently taking ART were enrolled in a home-based PA intervention aimed to reduce risk factors for CVD. Clinical assessments included measures of resting blood pressure (BP), waist circumference, height, weight, PA levels via accelerometer, and a fasted blood draw. Components of MetSyn were divided into three clusters (1 = 0–1; 2 = 2; 3 = 3 or more). A one-way analysis of variance was used to determine differences between clusters. Multiple linear regressions were used to identify significant associations between moderate intensity PA (MPA) and sedentary time among components of MetSyn. MPA was significantly lower across MetSyn clusters (p < 0.001), whereas sedentary time was significantly higher (p = 0.01). A multiple linear regression showed MPA to be a significant predictor of waist circumference after controlling for age, race, gender, and sedentary time. Routine PA can be beneficial in helping PLWHA reduce waist circumference ultimately leading to metabolic improvements. This in turn would help PLWHA self-manage known components of MetSyn, thus reducing their risk of CVD and mortality.

Moderate-Intensity Exercise Improves Body Composition and Improves Physiological Markers of Stress in HIV-Infected Men

HIV/AIDS and its treatment often alter body composition and result in poorer physical functioning. The aim of this study was to determine the effects of a moderate-intensity exercise program on body composition and the hormones and cytokines associated with adverse health outcomes. HIV-infected males (N = 111) were randomized to an exercise group (EX) who completed 6 weeks of moderate-intensity exercise training, or to a nonintervention control group (CON). In pre- and postintervention, body composition was estimated via DXA, peak strength was assessed, and resting blood samples were obtained. There was a decrease in salivary cortisol at wake (P = 0.025) in the EX and a trend (P = 0.07) for a decrease 1 hour after waking. The EX had a significant increase in lean tissue mass (LTM) (P < 0.001) following the intervention. Those in the EX below median body fat (20%) increased LTM (P = 0.014) only, while those above 20% decreased fat mass (P = 0.02), total fat (N = 0.009), and trunk fat (P = 0.001), while also increasing LTM (P = 0.027). Peak strength increased between 14% and 28% on all exercises in the EX group. These data indicate that 6 weeks of moderate-intensity exercise training can decrease salivary cortisol levels, improve physical performance, and improve body composition in HIV-infected men.

A home-based exercise intervention to increase physical activity among people living with HIV: study design of a randomized clinical trial

BackgroundWhile combination antiretroviral therapy has extended the life expectancy of those infected with human immunodeficiency virus (HIV), there is a high prevalence of comorbidities that increase the risk of cardiovascular morbidity and mortality among people living with HIV/AIDS (PLWHA). The side effects associated with antiretroviral therapy (ART) lead to multiple metabolic disorders, making the management of these metabolic issues and risk of cardiovascular disease (CVD) in those treated with ART a critical issue. Clinical research trials, primarily clinical exercise, rarely include this population due to unique challenges in research methods with underserved minority populations living with a life threatening illness like HIV/AIDS. This paper describes the rationale and design of a randomized clinical trial evaluating the feasibility of a home-based exercise program designed to increase physical activity (PA) and reduce the risk of CVD in PLWHA.Methods/designPLWHA being treated with ART will be randomly assigned to one of two groups: a home-based PA intervention or standard care. All participants will receive an educational weight loss workbook and pedometer for self-monitoring of PA. Only those in the intervention group will receive additional elastic Thera-bands® for strength training and behavioral telephone based coaching.DiscussionThis study will evaluate the feasibility of a home-based program designed to increase PA among PLWHA. Further, it will evaluate the effectiveness of such a program to decrease modifiable risk factors for CVD as a secondary outcome. This study was funded by the NIH/NINR R21 Grant 1R21NRO11281.Trial registrationClinical Trial Identifier NCT01377064

Association of Exercise Heart Rate Response and Incidence of Hypertension in Men

OBJECTIVE To examine the association of heart rate (HR) responses at rest, during exercise, and after exercise with incident hypertension (HTN) in men. PARTICIPANTS AND METHODS A total of 10,418 healthy normotensive men without abnormalities on electrocardiography or a history of myocardial infarction, stroke, cancer, or diabetes underwent a maximal exercise test and were followed up for incidence of HTN. Heart rate reserve was defined as the maximal HR minus resting HR. Heart rate recovery was defined as HR 5 minutes after the exercise test. RESULTS During a mean follow-up of 6 years, there were 2831 cases of HTN. Compared with men who had lower HR reserve, the risk of incident HTN was significantly lower for men with higher HR reserve (hazard ratio, 0.84; 95% CI, 0.74-0.95 for the highest quartile vs the lowest quartile of HR reserve; P=.002) when adjusted for age, baseline examination year, smoking, heavy drinking, body mass index, resting blood pressure, cholesterol and glucose levels, and cardiorespiratory fitness. Compared with men who had higher HR recovery, the risk of incident HTN was significantly lower for men with lower HR recovery (hazard ratio, 0.90; 95% CI, 0.80-0.99 for quartile 3 vs highest quartile; P=.04) after adjusting for the aforementioned confounders. However, the overall linear trend for HR recovery was not significant (P=.26). CONCLUSION The risk of HTN decreased in men with higher HR reserve. Therefore, HR reserve may be considered as a useful exercise parameter for predicting the risk of HTN in men.