Magnetism and Superconductivity in (Er₀.₁₆Ho₀.₈₄)Rh₄B₄

The superconducting and ferromagnetic phase boundaries in the (Er1-xHox)Rh4B4 mixed ternary alloy system meet in a multicritical point at xcr ≈ 0.9. For xcr, the compounds first become superconducting as the temperature is lowered, and then lose superconductivity in a transition to ferromagnetism. The coexistence of superconductivity and ferromagnetism for alloys near the erbium-rich end of the phase diagram is well established. It has also been suggested that ferromagnetism and superconductivity coexist in alloys with x just below xcr. We have carried out neutron-diffraction, ac magnetic susceptibility, and heat-capacity measurements on a sample of (Er0.16Ho0.84)Rh4B4 to investigate the possibility of coexistence of ferromagnetism and superconductivity for x ≈ xcr. We find that there are minor discrepancies in the superconducting and magnetic transition temperatures reported for different samples of (Er0.16Ho0.84)Rh4B4, but that ferromagnetism and superconductivity do occur simultaneously over a narrow temperature range in this sample. We suggest that an inhomogeneous state occurs, consisting of separate ferromagnetic and superconducting regions, rather than microscopic coexistence

Time-dependent Magnetic Structures of the Superconducting Mixed Ternary System Ho(Rh₁₋ₓIrₓ)₄B₄

Magnetic structures have been determined by netron diffraction for several compositions in the superconducting mixed ternary system Ho(Rh1-xIrx)4B4. Two features previously reported to occur in the heat capacity for some compositions are shown to correspond to successive magnetic transitions. For x=0.30 and 0.45, neutron diffraction peaks for the lowest temperature structure develop over a timescale of many hours. The results are discussed in terms of magnetic frustration

The Relationship of Metabolic Syndrome and Aerobic Exercise in Adult Male Fire Fighters

Previous studies have concluded that incidence of Metabolic Syndrome may be greater in male firefighters than in the US male population. A recent study reported that approximately 31% of firefighters were positive for Metabolic Syndrome; compared to 24% for the U.S. male population (NCEPIII). Participation in aerobic exercise may decrease the risk of Metabolic Syndrome as cardiac risk factors are improved. This study aims to determine the effect of aerobic exercise participation on the prevalence of metabolic syndrome in a sample of male firefighters. Purpose: To examine the effect of aerobic exercise participation on the prevalence of Metabolic Syndrome in a sample of adult male firefighters. Methods: As a part of an annual physical exam, 177 male firefighters (average age=36) participated in an evaluation of risk factors associated with Metabolic Syndrome as defined by NCEP III. Metabolic Syndrome is defined as having the presence of three or more of the following: Waist circumference \u3e 40”, HDL Cholesterol \u3c 40 mg/dl, Triglycerides \u3e 150 mg/dl, Blood Glucose \u3e 110 mg/dl and resting blood pressure \u3e 130/85 mm Hg. Aerobic exercise participation was determined by self reported activity from a standard health history questionnaire. Subjects were classified for aerobic exercise participation as: aerobic exercise participation of less than or equal to 1 day per week (LOW), 2 to 3 days per week (MOD), and aerobic exercise participation greater than or equal to 4 days per week (HIGH). Results: The subjects were divided into groups based on the level of weekly aerobic activity. All data were analyzed using a Chi Square test (p \u3c 0.05). Of the 177 firefighters tested 46.3% (82) reported LOW, 48% (85) reported MOD, and 5.6% (10) reported HIGH weekly aerobic activity. The prevalence of Metabolic Syndrome for LOW was 25.6% (21) while the prevalence of Metabolic Syndrome for MOD was 15.3% (13). No one in the HIGH group met the criteria for Metabolic Syndrome. Conclusion: Participation in aerobic exercise appears to affect the incidence of metabolic syndrome in adult male fire fighters

Prediction of the Total Energy Cost of an Acute Bout of Resistance Exercise in Young Men and Women

Prediction of the Total Energy Cost of an Acute Bout of Resistance Exercise in Young Men and Women Brad S. Lambert†, Steven E. Martin‡, John S. Green‡ (FACSM), Aaron F. Carbuhn†, Stephen F. Crouse‡ (FACSM). Department of Health and Kinesiology, Texas A&M University, College Station, TX (Sponsor S.F. Crouse) ACSM currently recommends resistance training (RT) for each major muscle group at least 2 times per week with a traditional repetition range of 8-12 per set. Because many investigators as well as fitness professionals consider kcal expenditure when creating training protocols, energy costs during both RT and aerobic training must be considered. PURPOSE: To develop a regression equation to predict kcal expenditure for a RT bout involving each major muscle group using VO2max, height, weight, lean body mass, fat mass, and total exercise volume (TV=sets*reps*wt) as independent variables. METHODS: Twelve subjects (7 men, 5 women, age 21-25 yrs) were tested using the standard Bruce treadmill protocol for VO2max, and strength tested to determine their 3-5 repetition max (RM) on Keiser® RT equipment 1 week prior to their experimental RT bout. Body composition was assessed using DEXA. For their experimental RT bout, a warm-up set followed by 2-3 sets of 8-12 reps at 60-70% predicted 1RM were performed for each exercise. Each set was started every two minutes. Exercises progressed in the following order: leg press, chest press, leg curl, lat pull, leg ext., triceps ext., biceps curl. Oxygen consumption was measured continuously throughout the RT bout using an automated metabolic cart. Multiple Linear Regression was used to determine the best model for prediction of kcal consumption. Results: Mean kcal expenditure for the entire RT bout was 221.8±20.65 kcal (men = 272±36 & women = 150±16) with a mean kcal cost of 26.32-38.94 per exercise. Large muscle group/multi-joint exercises had the highest total kcal expenditures as expected. Collinearity diagnostics from the regression revealed that VO2max (L/min) and the square root of TV (TV0.5) were the only predictors needed in the model with all other variables being highly intercorrellated with VO2max (L/min), thus not adding significant improvement to the model. The prediction equation was (p\u3c0.05, R2=0.86): Total kcal = (37.264*VO2max L/min) + (1.087*TV0.5) – 132.488 CONCLUSIONS: VO2max (L/min) and TV0.5 were found to be significant predictors of the energy cost of a RT bout involving each major muscle group. In regards to fitness, performance, and weight management, this equation may aid practitioners and young exercising adults in documenting kcal expenditure from resistance training

Association of Aerobic Fitness and Metabolic Syndrome in Male Firefighters

Metabolic syndrome has been shown in numerous studies to be related to a higher incidence of coronary artery disease. A study by Jurca and coworkers (Med. Sci. Sports Exerc 36(8):1301-1307, 2004) found a relationship between aerobic fitness and the prevalence of metabolic syndrome in a group of men enrolled in the Aerobics Center Longitudinal Study (ACLS). In addition, recent work in our lab (Int J Exerc Sci 2(1): S43, 2009) has supported these findings. However, research exploring this relationship is still lacking in male firefighters, whose leading cause of line-of-duty deaths is heart attacks. Purpose: To further evaluate the association of metabolic syndrome and aerobic fitness in male fire fighters. Methods: As part of an annual physical exam, 210 male fire fighters (average age = 36) underwent evaluation of risk factors associated with metabolic syndrome as defined by NCEP III. These include the presence of three or more of the following: Waist Circumference \u3e 40 , HDL Cholesterol \u3c 40 mg/dL, Triglycerides \u3e 150 mg/dL, Blood Glucose \u3e 110 mg/dL, and Resting Blood Pressure \u3e 130/85 mm Hg. Aerobic Fitness was determined by estimating VO2max from time on treadmill during a Bruce protocol. Results: The subjects were ranked and divided into quartiles based on VO2max. All data were analyzed using a Chi Square test (p \u3c 0.05). Prevalence of metabolic syndrome increased significantly across quartiles as aerobic fitness declined. Conclusion: These data suggest that as aerobic fitness improves, the likelihood of male firefighters having metabolic syndrome decreases

Exercise Blood Pressures Are Lower After Aquatic Compared To Land Treadmill Training

Exercise blood pressures are lower after aquatic compared to land treadmill training Alex T. Carradine1, Brad S. Lambert1, Nicolas P. Greene2, Travis W. Constanzo1, Steven E. Martin1, Stephen F. Crouse (FACSM)1. Texas A&M University, College Station, TX. 2University of Virginia, Charlottesville, VA. Traditional treadmill training has been shown to moderately decrease exercise blood pressures but the degree to which aquatic running alters exercise blood pressures has not been fully investigated. PURPOSE: To compare the exercise blood pressure responses after land treadmill (LTM) training to an equivalent volume of aquatic treadmill training (ATM). METHODS: We tested blood pressure responses to the Bruce treadmill protocol PRE and POST 12-wks of matched volume training on LTM (n= 9♂,13♀, age=43±3 yrs, weight=88.1±3.6 kg) or ATM (n=18♂, 17♀, age=45±2 yrs, weight=90.6±3.0 kg). Systolic (SBP), diastolic (DBP), pulse pressure (PP) and mean arterial pressure (MAP) were analyzed using a 2 (ATM or LTM) x 2 (PRE & POST) ANOVA repeated for the training time at rest, 3 stages of the exercise protocol, and 1 and 5 minutes of recovery; Tukey\u27s post hoc tests were used as follow-up for significant interactions, α=0.05. RESULTS: VO2max increased significantly 11-15% with training in both groups. Significant training changes for MAP shown in Table (mmHg, mean±SE); SBP and PP paralleled these results. Significance remained after covarying for BMI, %body fat, and age. GROUP (TIME) STG 1 STG 2 PEAK REC 1 REC 5 ATM (PRE) 105.9 ±1.9 112.3 ±2.1 115.2 ±1.8 111.4 ±1.9 99.7 ±2.3 ATM (POST) 99.8 ±1.5* 104.1 ±1.2* 110.4 ±1.3* 105.9 ±1.3* 93.6 ±1.3* LTM (PRE) 105.1 ±1.9 110.1 ±1.8 113.9 ±1.3 111.1 ±1.7 99.6 ±2.1 LTM (POST) 103.0 ±1.9 106.8 ±2.1 112.1 ±1.5 110.8 ±1.7 101.4 ±2.5 * = Within group by time (p\u3c0.05). Bruce Protocol Stage (STG) 1, 2, Peak; Recovery (REC) 1,5 minutes CONCLUSION: ATM significantly reduces exercise blood pressures. These data suggest ATM may provide a superior benefit over LTM for promoting said reduction

Association of Cardiovascular Fitness and Syndrome X in Male Firefighters

Metabolic syndrome has been shown in numerous studies to be related to a higher incidence of coronary artery disease. A study by Jurca and coworkers (Med. Sci. Sports Exerc 36(8):1301-1307, 2004) found a relationship between cardiovascular fitness and the prevalence of metabolic syndrome in a group of men enrolled in the Aerobics Center Longitudinal Study (ACLS). In addition, recent work in our lab (Int J Exerc Sci 2(1): S43, 2009) has supported these findings. However, research exploring this relationship is still lacking in male firefighters, whose leading cause of line-of-duty deaths is heart attacks. Purpose: To further evaluate the association of metabolic syndrome and cardiovascular fitness in male fire fighters. Methods: As part of an annual physical exam, 224 male fire fighters (average age = 36) underwent evaluation of risk factors associated with metabolic syndrome as defined by NCEP III. These include the presence of three or more of the following: Waist Circumference \u3e 40 , HDL Cholesterol \u3c 40 mg/dL, Triglycerides \u3e 150 mg/dL, Blood Glucose \u3e 110 mg/dL, and Resting Blood Pressure \u3e 130/85 mm Hg. Cardiovascular Fitness was determined by estimating VO2max from time on treadmill during a Bruce protocol. Results: The subjects were ranked and divided into quartiles based on VO2max. All data were analyzed using a Chi Square test (p \u3c 0.05). Prevalence of metabolic syndrome increased significantly across quartiles as cardiovascular fitness declined. Conclusion: These data suggest that as cardiovascular fitness improves, the likelihood of male firefighters having metabolic syndrome decreases

Cross-validation of a Prediction Equation for Energy Expenditure of an Acute Resistance Exercise Bout

Previously, our laboratory introduced a regression equation for predicting net kcal consumption of a resistance exercise (RE) bout: Total net kcal = 0.874(height, cm) - 0.596(age, years) - 1.016(fat mass, kg) + 1.638(lean mass, kg) + 2.461(total volume x 10-3) - 110.742 (R2 = 0.773, SEE=28.5 kcal). PURPOSE: The purpose of this study was to validate this regression equation using the same variables as predictors. METHODS: Forty-seven healthy, active subjects (23 men, 24 women, 20-58 yrs, 173.5 ± 10.5 cm, 85.5 ± 19.0 kg, VO2max 36.0 ± 8.4 ml/kg/min) were randomly divided into validation and cross-validation groups (nv = 24, ncv = 23). The validation group’s data was used to develop an equation to predict net kcal consumption, which was applied to the cross-validation group’s data to estimate net kcal consumption. Similarly, a prediction equation was derived from the cross-validation group’s raw data and applied to that of the validation group. The strength of the relationship between each group’s measured and estimated net kcal consumption was assessed via correlational analysis. RESULTS: Multiple linear regression yielded the following estimates of net kcal consumption: validation net kcal = 1.125(height, cm) – 0.662(age, years) – 0.800(fat mass, kg) + 1.344(lean mass, kg) + 2.278(total volume x 10-3) – 144.846 (R2 = 0.751, p \u3c 0.0001, SEE=29.7 kcal); cross-validation net kcal = 0.515(height, cm) - 0.520(age, years) - 1.220(fat mass, kg) + 1.995(lean mass, kg) + 2.620(total volume x 10-3) – 59.988 (R2 = 0.823, p \u3c 0.0001, SEE=29.2 kcal). These equations had a cross-validation coefficient of 0.902 and a double cross-validation coefficient of 0.863. CONCLUSION: The strong relationship between the measured and estimated net kcal consumption of both the cross-validation and validation group lead us to conclude that the regression equation derived by this laboratory is valid for estimating net energy expenditure for a total RE bout

Changes in PPARδ Protein Content following Acute Aerobic Exercise in Human Vastus Lateralis Muscle.

PPARδ is a transcription factor which functions in the regulation of lipid and glucose metabolism, and may be implicated as a therapeutic target for several metabolic diseases. Exercise training has previously been shown to increase PPARδ protein content, but the response of PPARδ to acute exercise is not yet understood. PURPOSE: To explore changes in PPARδ protein content following an acute bout of aerobic exercise in untrained obese adults. METHODS: 8 men and 4 women participated in the study. Subjects’ mean age, weight, VO2MAX (Bruce treadmill GXT), and body composition (DEXA) were 44 yr, 93.2 kg, 28.2 mL/kg/min, and 40.5% body fat, respectively. Subjects were asked to refrain from exercise for 1 week prior to the experiment and to maintain normal dietary habits during the study. Muscle biopsies were obtained from the vastus lateralis 3 days prior to acute exercise and again 24 hours after exercise. Subjects were exercised on a motorized treadmill at 70% VO2MAX for a target duration of 400kcal energy expenditure during the exercise session. PPARδ protein content in biopsied tissue was determined by Western blot analysis. Data were analyzed by repeated measures ANOVA and expressed as means ± standard error. RESULTS: PPARδ content was enhanced 24 hours following acute exercise in previously untrained, obese adults (unexercised 1.54±0.38 vs. exercised 2.30±0.39 arbitrary units, P\u3c0.05). Gel mobility shift indicated no difference in activity of PPARδ (phosphorylated: total) following exercise (unexercised 0.36±0.03 vs. exercised 0.34±0.04). CONCLUSION: Our study shows that PPARδ expression is enhanced in untrained, obese adults following a single bout of aerobic exercise with no relative change in phosphorylation of PPARδ. These data indicate that acute exercise plays a role in the expression of PPARδ. Funding for this research was provided by HydroWorx International, Inc., the Sydney & J.L. Huffines Institute for Sports Medicine and Human Performance at Texas A&M University and The Texas Chapter of The American College of Sports Medicin