Interactions between adipose, bone, and muscle tissue markers during acute negative energy balance in male rowers.

AIM: The purpose of this investigation was to study the influence of prolonged low-intensity single scull rowing exercise on plasma adipocytokine and osteokine concentrations in trained male rowers. Nine single scull rowers (age: 20.1±1.6 yrs; height: 184.1±4.6 cm; body mass: 81.2±5.3 kg; %body fat: 11.1±3.9) participated in this study. METHODS: Venous blood samples were obtained before and after a ~2 h constant load on-water sculling training session (distance: 20.6±1.5 km; HR: 133±4 bpm; intensity: 80.3±1.7% of the HR turn-point). RESULTS: The training session created an energy deficit of 1 200-1 500 kcal. Plasma adiponectin increased (+12.2%; P<0.05) while leptin decreased (-23.1%; P<0.05) at 30 min postexercise. Plasma osteocalcin (+23.7%; P<0.05) and type I carboxyterminal telopeptide (ICTP) (+28.6%; P<0.05) were increased on completion of the training session. Plasma IL-6 concentration was increased (P<0.05) about four-fold while insulin concentration was decreased (P<0.05) more than three-fold upon completion of exercise. There were no differences in TNF-α, glucose, testosterone and cortisol concentrations over time. Plasma adiponectin (r=0.59) and osteocalcin (r=0.57) concentrations measured immediately after the training session were related (P<0.05) to the distance covered. CONCLUSION: Acute negative energy balance induced by a single endurance rowing training session elicited an inverse metabolic response in adiponectin and osteocalcin concentrations in male rowers. Our results suggest that peripheral markers of negative energy balance, such as adiponectin and osteocalcin, may serve as signals for metabolic reaction to the energy cost of acute exercise in athletes.

Measuring energy expenditure in cardiac patients using the Body Media Armband versus indirect calorimetry. A validation study.

AIM: The purpose of this study was to compare differences in energy expenditure using the newly developed SenseWear Armband body monitor to indirect calorimetry in cardiac rehabilitation patients. METHODS: Twenty-four (62+/-8.1 years) patients completed steady state exercise for 8 minutes on 4 modes of exercise (arm ergometry, treadmill walking, recumbent stepping and rowing ergometry). Total cumulative kilojoules were recorded simultaneously by indirect calorimetry and the SenseWear Armband. Statistical analyses assessed the degree of agreement between the 2 measurement methods and 3 different versions of the SenseWear software. RESULTS: The correlations between indirect calorimetry and version 2.2 of the SenseWear armband for arm and rowing ergometry, the treadmill and recumbent stepper were r=0.90, r=0.67, r=0 .80 and r=0.74, respectively. There were no between method differences during arm ergometry (p<1.000) and the recumbent stepper (p<0.102). Bland and Altman plots revealed the greatest spread of scores for the rower and the treadmill. Between method differences were minimal when using the preliminary cardiac software. The correlations for arm and rowing ergometry, the treadmill and recumbent stepper were r=0.90, r=0.84, r=0.78 and r=0.82, respectively. CONCLUSIONS: The accuracy of the BodyMedia SenseWear Armband appears to be exercise modality dependent in those with heart disease when using software developed for the general population. Therefore, the information should be interpreted cautiously, particularly during treadmill walking and rowing. Initial experiments with cardiac-focused software are promising, but preliminary.

Follow up exercise studies in paediatric obesity: implications for long term effectiveness.

OBJECTIVES: To examine the effects of exercise training on paediatric obesity immediately after training and at a one year follow up and to provide recommendations for future research. METHODS: Studies that met the following criteria were included in a meta-analysis: (a) at least six subjects per group; (b) subject groups consisting of children in the 4-17 year age range; (c) pre-test and post-test values for body composition; (d) used exercise such as walking, jogging, cycle ergometry, high repetition resistance exercise, and combinations; (e) training programmes lasting eight weeks or more; (f) full length publications; (g) apparently healthy children. RESULTS: A total of 135 studies of exercise as a method of treatment of paediatric obesity were located. Eight, containing 236 subjects, met our criteria for inclusion. Across all designs and categories, fixed effects modelling yielded significant decreases in the dependent variable percentage body fat immediately (0=1.04 (0.35); 95% confidence interval (CI) 0.41 to 1.6) and one year after the exercise intervention (0=0.84 (0.51); 95% CI 0.22 to 0.94). Forward stepwise linear regression suggested that the percentage body fat measured at the end of exercise training, exercise duration, and programme length accounted for 53-86% of the variance for percentage body fat at one year. CONCLUSIONS: These data indicate that exercise is efficacious for reducing percentage body fat in obese children and adolescents, and that exercise intervention may encourage long term maintenance of the observed gains.

%HRmax target heart rate is dependent on heart rate performance curve deflection.

UNLABELLED: The percent of maximal heart rate (%HRmax) model is widely used to determine training intensities in healthy subjects and patients when prescribing training intensities in these groups of subjects. PURPOSE: The aim of the study was to investigate the influence of the time course of the heart rate performance curve (HRPC) on the accuracy of target training heart rate. METHODS: Sixty-two young healthy male subjects performed an incremental cycle ergometer exercise test until voluntary exhaustion. Subjects were then divided into four groups according to the time course of the HRPC. Groups were classified in regular HR response (kHR2 > 0.2), indifferent HR response (0 < kHR2 < 0.2), linear HR response (kHR2 = 0), and inverted HR response (kHR2 < 0). The first and the second lactate turn point (LTP1, LTP2) as well as the heart rate turn point (HRTP) were determined as submaximal markers of performance. Linear regression lines were calculated for HR in the three regions of energy supply defined by LTP1 and LTP2. RESULTS: HR at LTP1 and HRmax was not significantly different between all four groups. HR at LTP2 was dependent on the time course of the HRPC and was significantly lower (P < 0.05) as kHR2 decreased. Power output and blood lactate concentration at LTP1, LTP2 and maximal workload (Pmax) were not significantly different between the groups. CONCLUSION: From our data, we conclude that target training HR detected by means of the %HRmax method may be overestimated in cases where the HR response is not regular, as it was found in many of our subjects.

Treadmill and cycle ergometry testing in 5- to 6-year-old children.

The primary purpose of this study was to determine the maximal cardiorespiratory responses of 48, 5- to 6-year-old children (24 girls and 24 boys), who were tested on a treadmill (TM) and an electronically braked cycle ergometer (CE). We also examined the percentage of boys and girls who were able to achieve the criteria for reaching maximal oxygen consumption (VO2max) on each testing mode. After an orientation period, each child was tested twice (once on the TM and once on the CE), with an interval of 1 week between tests. VO2max was measured during progressive, all out, continuous TM and CE tests using standardized procedures. A 2 x 2 analysis of variance test (genderxexercise mode) with Bonferroni adjustment revealed the following: (1) there were no gender differences in any of the measured dependent variables, (2) the children produced a significantly higher relative VO2max (ml x kg(-1) x min(-1) and a higher absolute VO2max (l x min(-1)) on the TM than on the CE (P < 0.001), (3) the children produced a higher heart rate on the TM than on the CE (P < 0.001), (4) the CE generated significantly higher values for respiratory exchange ratio (P < 0.001), (5) the criteria necessary to establish a maximal exercise effort were achieved on both the TM and the CE, and (6) all of the children reached two of the criteria associated with a maximal effort, while only 46% of the children reached three criterion measures. There were no significant differences in the attainment of criterion measures between the TM and the CE. The results of this study indicate a lack of gender differences in maximal exercise testing in 5- to 6-year-old children, and that both the CE and the TM are effective modes of maximal cardiorespiratory testing in this age group.

Lipid and lipoprotein profiles, cardiovascular fitness, body composition, and diet during and after resistance, aerobic and combination training in young women.

The purpose of this study was to evaluate the effects of various modes of training on the time-course of changes in lipoprotein-lipid profiles in the blood, cardiovascular fitness, and body composition after 16 weeks of training and 6 weeks of detraining in young women. A group of 48 sedentary but healthy women [mean age 20.4 (SD 1) years] were matched and randomly placed into a control group (CG, n = 12), an aerobic training group (ATG, n = 12), a resistance training group (RTG, n = 12), or a cross-training group that combined both aerobic and resistance training (XTG, n = 12). The ATG, RTG and XTG trained for 16 weeks and were monitored for changes in blood concentrations of lipoprotein-lipids, cardiovascular fitness, body composition, and dietary composition throughout a 16 week period of training and 6 weeks of detraining. The ATG significantly reduced blood concentrations of triglycerides (TRI) (P < 0.05) and significantly increased blood concentrations of high-density lipoprotein-cholesterol (HDL-C) after 16 weeks of training. The correlation between percentage fat and HDL-C was 0.63 (P < 0.05), which explained 40% of the variation in HDL-C, while the correlation between maximal oxygen uptake (VO2max) and HDL-C was 0.48 (P < 0.05), which explained 23% of the variation in HDL-C. The ATG increased VO2max by 25% (P < 0.001) and decreased percentage body fat by 13% (P < 0.05) after 16 weeks. Each of the alterations in the ATG had disappeared after the 6 week detraining period. The concentration of total cholesterol (TC), TRI, HDL-C and low density lipoprotein-cholesterol in the blood did not change during the study in RTG, XTG and CG. The RTG increased upper and lower body strength by 29% (P < 0.001) and 38%, respectively. The 6 week detraining strength values obtained in RTG were significantly greater than those obtained at baseline. The XTG increased upper and lower body strength by 19% (P < 0.01) and 25% (P < 0.001), respectively. The 6 week detraining strength values obtained in XTG were significantly greater than those obtained at baseline. The RTG, XTG and CG did not demonstrate any significant changes in either VO2max, or body composition during the training and detraining periods. The results of this study suggest that aerobic-type exercise improves lipoprotein-lipid profiles, cardiorespiratory fitness and body composition in healthy, young women, while resistance training significantly improved upper and lower body strength only.

The effects of physical training of functional capacity in adults. Ages 46 to 90: a meta-analysis.

BACKGROUND: There is a progressive decline in the functional capacity (FC) of the cardiovascular system with aging. This deterioration is reflected in a decrease in the maximal oxygen consumption (VO2max). The purpose of this quantitative review was to determine the effects of various components of the exercise prescription on FC in older individuals (ages 46-90 years). METHODS: This study synthesized the results of 27 studies by meta-analysis, which generated a total of 34 effect sizes. Each effect size represented an independent measure of the impact of physical training on maximal oxygen consumption (VO2max). A total of 720 subjects were included in this review. The studies were coded according to intensity, session duration, length of training and mode of exercise. RESULTS: A significant difference was found (p < 0.001) in FC between studies in which the intensity of exercise was > or = to 80% of VO2max compared to those with training intensities of 60-75% of VO2max. A significant difference was found (p < 0.002) for exercise duration; namely, a duration of > or = 30 minutes produced significantly greater improvements in VO2max when compared to an exercise duration less than 30 minutes. There was no significant difference reported in FC between studies that lasted 15 or more weeks in duration compared to those that lasted less than 15 weeks. Finally, there was no significant difference reported in FC in studies that utilized a walk/jog training mode compared to those which utilized cycle ergometry. CONCLUSIONS: Despite the inevitable decline in VO2max with aging, exercise training imparts favorable adaptations in FC in individuals well into their seventh and eighth decades of life.

Evaluation of physical activity measured via accelerometry in rural fourth-grade children.

Interest in the benefits of exercise has prompted increased research examining the relationship between physical activity and health status in adults. More recently, considerable research effort has been directed toward the role of physical activity in young children as a precursor to adult physical fitness. The purpose of this study was to estimate the relationship between physical activity measured via accelerometry and body mass index, body mass, body composition, and physical fitness in fourth-grade boys and girls during physical education lessons. 54 fourth-grade students in rural Pennsylvania (28 girls, M age 9.6, SD = .56; 26 boys, M age 9.5, SD = .51) were subjects. Girls were significantly less active during all lessons measured (p < .001). The results of linear regression analyses indicated that physical activity was negatively associated with body mass index, body mass, and body fat percentage (p < .05), and positively associated with physical fitness (VO2max) (p < .01). These data indicate the need for curricular intervention to motivate girls to increase their activity during structured physical education lessons and demonstrate the efficacy of the body mass index as a screening tool within the schools.

Exercise tolerance, body composition and blood lipids in obese African-American women following short-term training.

BACKGROUND: The purpose of this investigation was to examine the exercise tolerance, body composition and blood lipids in African-American women, possessing greater than or equal to 30% body fat, following six weeks of endurance training. METHODS: Oxygen consumption (VO2), central hemodynamics, blood lipids, body weight, body fat, and the body mass index of seven subjects (21.0 +/- 0.8 yrs) were studied. Heart rate (HR), blood pressure (BP), exercise duration, rating of perceived exertion (RPE), blood lactate (bLA) and VO2 were obtained in response to a maximal exercise tolerance test on a motorized treadmill. Subjects trained three times per week for 50 minutes per session (30 minutes at 70% maximal oxygen consumption (VO2max). RESULTS: Dependent "t"-tests revealed significant (p < 0.05) increases in VO2max, 27%; exercise duration, 31%; as well as peak HR, systolic blood pressure (SBP), and bLA. Values for submaximal HR, SBP, RPE during the post-training test were lower. In addition, body weight, body fat and the body mass index decreased 2.2%, 1.3% and 3.4% respectively. There were no changes in blood lipids. CONCLUSIONS: These findings suggest short-term training at 70% VO2max provides the necessary stimulus for obese women to improve exercise tolerance and body composition. However, the training stimulus is insufficient to alter lipid profiles.

Determination of lactate threshold by respiratory gas exchange measures and blood lactate levels during incremental load work.

OBJECTIVE: The purpose of this investigation was the determination of the lactate threshold (LT) by selected respiratory gas exchange measures and venous blood lactate levels during incremental load work on a mechanically braked cycle ergometer. DESIGN: Repeated measures design. SETTING: Human Performance Laboratory. PARTICIPANTS: Eight healthy trained soccer players (mean age 21.9 +/- 3.0 yr, mean VO2max = 59.2 +/- 3.6 ml.kg.min-1). OUTCOME MEASURE: Subjects conducted two incremental load work tests. Incremental load work was increased by 1 kilopond (kp) every third minute at 60 rpm until voluntary exhaustion. Blood samples from a forearm vein were collected during the second trial (T2) only and analyzed for lactic acid [LA-]. RESULTS: One-way analysis of variance (ANOVA) with repeated measures indicated no statistically significant difference between the two tests for maximal oxygen uptake (VO2max), maximal carbon dioxide production (VCO2max), maximal heart rate (HRmax), maximal pulmonary ventilation (VEBTPSmax) and lowest ventilatory equivalent of oxygen (VE/VO2), respectively; however, there was a significant difference among the oxygen uptake (VO2) values at the LT for the four determination methods. In our subjects, the measured (mean +/- SD) VE/VO2 in relation to VO2 for the first trial (T1) of 22.9 +/- 1.9 occurred at VO2 of 1.27 +/- 0.8 l.min-1. The lowest VE/VO2 and the onset of [LA-] accumulation calculated from individual exponential equations relating VE to VO2 yielded VO2 values of 1.77 +/- 0.18 and 1.74 +/- 0.25 l.min-1 for the T2. Utilizing natural log for lactate ln [LA-] to natural log for ln (VO2) equations, the LT for T2 occurred at VO2 of 1.30 +/- 0.70 l.min-1. CONCLUSION: LT was best predicted by the measured lowest VE/VO2 and the plot of the ln [LA-] to ln VO2 relationship. The methods used in this study provide a valid estimate of the LT and support the use of measured lowest VE/VO2 as an indirect measure of the LT.

Interrelationship between plasma potassium concentration, pulmonary ventilation and electrocardiographic change during and after highly intense exercise.

OBJECTIVE: The purpose of this investigation was to induce elevated plasma concentrations of potassium (K+) efflux from active muscle cells during intense muscular exercise. The relationship between K+, pulmonary ventilation (VE) and EKG changes, specifically T-wave amplitude, is presently controversial. DESIGN: Repeated measures design. SETTING: Human performance laboratory. PARTICIPANTS: Twelve volunteer trained recreational cyclists (10 males, mean age 31.9 +/- 7.4, and 2 females, mean age 27.5 +/- 0.7, mean VO2max 571.2 +/- 6.4 ml.kg.min-1). OUTCOME MEASURE: Subjects performed 10 min of pedaling at 90 rpm, yielding a power output of 45 W.min-1 on a mechanically braked cycle ergometer as a warm-up. Each exercise stage was 2 min in duration, beginning at 135 W and increased by 45 W thereafter until voluntary exhaustion. Respiratory gas exchange measures were obtained every 10 sec. Venous blood samples for K+ and lactate (LA-) determination were drawn at rest, at the end of stage 2, all subsequent stages, and during 3 and 10 min of recovery. EKG recordings were concurrent with venous sampling. RESULTS: Statistical analyses for VE vs. K+, respiratory exchange ratio (RER) vs. K+ and RER vs. LA- revealed neither significant change nor an associative relationship from stages 1-3. However, stages 4-8 were statistically significant (p < .05) and highly correlated. No relationship was found between K+ change and T-wave amplitude during exercise or recovery. CONCLUSION: These data indicate a strong relationship between selected respiratory gas exchange measures and K+ during intermediate to highly intense exercise.