Lisa G. Johnson

Concurrent cardiovascular and resistance training in healthy older adults.

PURPOSE The recommendations for exercise training and physical activity for older adults include cardiovascular and resistance training components (CVT and RT, respectively). The purpose of the present investigation was to compare the fitness benefits of concurrent CVT and RT with those attained through an equivalent duration of CVT or RT alone. METHODS Thirty-six participants (ages 60-84) were assigned to a control group or to one of three exercise treatment groups. The treatment groups exercised three times per week for 12 wk using RT (N = 11), CVT (N = 10), or CVT and RT (BOTH, N = 9). Pre- and post-training, participants performed a submaximal exercise test (GXT), five repetition-maximum strength tests (5RM), and the AAHPERD functional fitness test for older adults. RESULTS All exercise treatment groups revealed lower resting heart rate and rate-pressure product; lower exercise diastolic blood pressure and rating of perceived exertion; increased GXT duration; increased leg, back, and shoulder 5RM scores; and improved AAHPERD flexibility, coordination, and cardiovascular endurance scores. The exercise treatment groups responded differently on the following: RT and BOTH enhanced arm and chest strength more than CVT; and BOTH enhanced AAHPERD strength and agility scores more than CVT or RT. CONCLUSIONS Concurrent CVT and RT is as effective in eliciting improvements in cardiovascular fitness and 5RM performance as CVT or RT, respectively. Moreover, incorporating both CVT and RT in exercise programs for older adults may be more effective in optimizing aspects of functional fitness than programs that involve only one component.

Rigorous Running Increases Growth Hormone and Insulin-Like Growth Factor-I Without Altering Ghrelin

It has been suggested that ghrelin may play a role in growth hormone (GH) responses to exercise. The present study was designed to determine whether ghrelin, GH, insulin-like growth factor-I (IGF-I), and IGF-binding protein-3 (IGFBP-3) were altered by a progressively intense running protocol. Six well-trained male volunteers completed a progressively intense intermittent exercise trial on a treadmill that included four exercise intensities: 60%, 75%, 90%, and 100% of Vo2max. Blood samples were collected before exercise, after each exercise intensity, and at 15 and 30 mins following the exercise protocol. Subjects also completed a separate control trial at the same time of day that excluded exercise. GH changed significantly over time, and GH area under the curve (AUC) was significantly higher in the exercise trial than the control trial. Area under the curve IGF-I levels for the exercise trial were significantly higher than the control trial. There was no difference in the ghrelin and IGFBP-3 responses to the exercise and control trials. Pearson correlation coefficients revealed significant relationships between ghrelin and both IGF-I and IGFBP-3; however, no relationship between ghrelin and GH was found. In conclusion, intense running produces increases in total IGF-I concentrations, which differs from findings in previous studies using less rigorous running protocols and less frequent blood sampling regimens. Moreover, running exercise that produces substantial increases in GH does not affect peripheral ghrelin levels; however, significant relationships between ghrelin and both IGF-I and IGFBP-3 exist during intense intermittent running and recovery, which warrants further investigation.

Adiponectin responses to continuous and progressively intense intermittent exercise.

PURPOSE Adiponectin is a recently discovered adipocyte protein that is lower in patients with coronary artery disease and in Type II diabetics who have insulin resistance. Regular exercise is known to be a preventative factor in the development of atherosclerosis and Type II diabetes. Acute exercise increases insulin sensitivity; however, it also increases beta-adrenergic and glucocorticoid activities that may suppress adiponectin expression. Two experiments were conducted to determine whether acute exercise affects adiponectin concentrations. METHODS In the first experiment, six healthy male subjects completed 30 min of heavy continuous running exercise at 79% of VO (2max). In the second experiment, well-trained runners completed strenuous intermittent exercise consisting of treadmill running at 60, 75, 90, and 100% VO (2max). A resting control trial for the second experiment was also conducted. RESULTS Glucose and insulin were not altered significantly in the first experiment, but both increased significantly (P < 0.05) in the second experiment. A significant increase (P < 0.05) in adiponectin in the first experiment was no longer significant after correction for plasma volumes shifts. In the second experiment, there were significant (P < 0.05) changes in adiponectin concentrations over time but not a significant difference between adiponectin responses in exercise and control trials. CONCLUSIONS The data suggest that 30 min of heavy continuous running or more strenuous intermittent running does not stimulate an increase in production and release of adiponectin, and small increases in adiponectin concentrations resulting from the exercise may be attributed to normal plasma volume shifts.

Effects of estrogen replacement therapy on dehydroepiandrosterone, dehydroepiandrosterone sulfate, and cortisol responses to exercise in postmenopausal women

OBJECTIVE To determine the effects of hormone replacement therapy (HRT) on dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and cortisol (F) responses to treadmill exercise. DESIGN Controlled clinical study. SETTING Female volunteers in an academic research environment. PATIENT(S) Sixteen healthy, postmenopausal women (7 were receiving HRT, 9 were not). INTERVENTION(S) Blood samples were taken from an intravenous catheter before, during, and after 30 minutes of treadmill exercise following an overnight fast. A second session was conducted one month later for the same subjects using the same blood sampling protocol without exercise. MAIN OUTCOME MEASURE(S) Serum DHEA, DHEAS, and F concentrations. RESULT(S) The HRT and untreated DHEA area under the curve (AUC) for the exercise trials was significantly greater than that for the control trials. The untreated, but not the HRT, DHEAS AUC for the exercise trials was significantly greater than that for the control trials. The HRT and untreated F AUC for the exercise trials was significantly greater than that for the control trials. The AUC for the HRT exercise trials was significantly higher than the untreated exercise trials for DHEA and F, but not DHEAS. CONCLUSION(S) Data suggest that treadmill exercise elevates DHEA, DHEAS, and F levels in postmenopausal women and that HRT enhances the DHEA and F responses.

Effects of high-intensity exercise on leptin and testosterone concentrations in well-trained males.

Objective: A number of investigations have examined the effect of exercise on leptin concentrations, because leptin is associated with obesity, satiety, and reproductive function. High-intensity exercise is known to increase testosterone, an inhibitor of leptin. The objective of the study was to determine whether the leptin responses to a progressive, intermittent exercise protocol were related to serum testosterone concentrations. Most previous studies have examined leptin responses to low or moderately high exercise intensities. A second objective was to determine whether leptin responses were different than previous experiments using intermittent moderate and high-intensity exercise.Methods: Well-trained runners completed strenuous intermittent exercise consisting of treadmill running at 60, 75, 90, and 100% VO2max and a subsequent resting control trial was also conducted.Results: There were significant increases in mean serum levels of leptin and testosterone with both quickly returning to baseline during recovery, but no relationship between the two hormones was found. After examining individual data for both hormones, it was discovered that subjects could be classified as leptin responders or nonresponders, whereas testosterone increased in all subjects. Responders had elevated serum leptin levels at baseline and exhibited increases after high-intensity exercise, whereas nonresponders did not show changes in leptin during exercise.Conclusions: Data suggest testosterone levels do not acutely affect leptin responses to exercise or 1-h of recovery. Moreover, varied leptin responses to intense exercise in comparable well-trained runners was observed and was associated with baseline leptin concentrations.

Endurance and resistance training lowers C-reactive protein in young, healthy females

The purpose of this study was to determine whether endurance (E) or endurance + resistance (ER) training affects C-reactive protein (CRP) and if these changes are related to alterations in fitness and (or) body composition in young females. Thirty-eight females (aged 18-24 years) were assigned to 1 of 3 groups: (1) E, (2) ER or (3) active control (AC). The E and ER groups completed 15 weeks of marathon training. The ER group performed additional resistance training and the AC group maintained their usual exercise routine. Primary outcomes were measured pre- and post-training and included anthropometric indices, dual-energy x-ray absorptiometry, plasma CRP, time to complete 1.5 miles (in minutes), and upper and lower body strength tests (i.e., 8 repetition max on bench and leg press (ER group only)). There were no differences in any variable among the groups at baseline. After training, the E group decreased time to complete 1.5 miles (p < 0.05). The AC group decreased percent and absolute body fat while the E group decreased percent body fat, absolute body fat, and android and gynoid body fat (p < 0.05). The ER group significantly improved strength (p < 0.001) and reduced plasma CRP from 2.0 ± 1.1 to 0.8 ± 0.3 mg·L(-1) (p = 0.03). No significant associations were observed between CRP and measures of body composition or aerobic capacity. Combined endurance and resistance training may be an effective modality for reducing plasma CRP in young adult females independent of changes in aerobic capacity or body composition.

Self-reported physical activity improves prediction of body fatness in young adults.

PURPOSE To examine self-reported physical activity levels from the International Physical Activity Questionnaire (IPAQ) as an independent predictor of dual-energy x-ray absorptiometry (DXA)-measured percent body fat (%BF) from body mass index (BMI), gender, and race. METHODS Two hundred and seventy-eight students, aged 18-24 yr, volunteered to participate. There were 133 males (85 white and 48 black) and 145 females (77 white and 68 black). Total activity levels were quantified in MET hours per week (MET h wk(-1)) using the IPAQ short form. Height and weight were measured, and BMI values were calculated (kg m(-2)). %BF was assessed using DXA. Linear regression analysis was used to develop and compare a body fat prediction equation with (full) and without (reduced) the variable MET-h.wk. Both models included BMI, gender, and race as predictor variables. The prediction sum of squares (PRESS) statistic was used to cross-validate both models, and the individual predictive accuracy was compared using modified Bland-Altman plots. RESULTS Mean +/- SD values were as follows: BMI = 24.4 +/- 4.1 kg m(-2), %BF = 24.5 +/- 9.3%, and MET h wk(-1) = 37.4 +/- 21.9. Gender, BMI, and race explained 81% of the variance in %BF, with a root mean square error (RMSE) of 4.07. The full model with MET-h.wk improved the prediction of %BF by 2% (R2 = 0.83, RMSE = 3.87). When cross-validated, the corresponding PRESS statistics for the reduced and full model were 4.10 and 3.90, respectively. Bland-Altman limits of agreement were greater for the reduced model compared with the full model (-8.09, 8.10 vs -7.67, 7.68). CONCLUSION These results suggest that %BF can be predicted with greater precision and accuracy in a young adult population when MET-h.wk are included in addition to BMI, gender, and race.

Implementing Service-Learning Through a Community-Based Fitness Program

Louisiana State University’s School of Kinesiology has partnered with the Dr. Leo S. Butler Community Fitness Center in Baton Rouge, LA since 2003 offering our fitness studies concentration majors a unique service-learning experience. The center is located in a community with citizens battling many health issues, such as high blood pressure and diabetes, with limited access and resources that promote a heathy lifestyle. Students enrolled in a senior capstone course work with the community members in the Sensational Seniors fitness program. This fitness program addresses some of those needs by providing a variety of group exercise sessions promoting overall health and longevity for the participants. Our students are able to apply theoretical concepts learned in lectures and laboratories to address public health concerns in a real-life setting. The students lead group fitness activities, monitor blood pressures, and disseminate appropriate and updated health and exercise information for the seniors.