Heart rate recovery to assess fitness: comparison of different calculation methods in a large cross-sectional study

We propose a cross-sectional study based on 980 maximal effort tests to quantify the effect of the calculation method of heart rate recovery (HRR) on its association with cardiorespiratory fitness (CRF). For five different time t₀ after exercise cessation, HRR has been calculated as: the difference and the ratio between maximal measured heart rate and heart rate (HR) at t₀HR at t₀the decay time of an exponential decay encompassing the first t₀ minutes of the HR recovery.The associations between HRR indices and CRF were estimated from generalized estimating equations stratified by gender and adjusted for age and body mass index. For HRR indices based on exponential regression, no significant association with CRF was found, whereas the other HRR indices are associated with CRF when t₀ is at least 1 minute and is maximum for t₀ = 2 minutes for females and t₀ = 3 minutes for males.

Utility of estimated pulse wave velocity for assessing vascular stiffness: comparison of methods

Background: Pulse wave velocity independently predicts cardiovascular risk. Easy to use single cuff oscillometric methods are utilized in clinical practice to estimate pulse wave velocity. We applied the approach in master athletes to assess possible beneficial effects of lifelong exercise on vascular health. Furthermore, we compared single cuff measurements with a two-cuff method in another cohort.

Methods: We obtained single cuff upper arm oscillometric measurements thrice in 129 master athletes aged 35 to 86 years and estimated pulse wave velocity using the ArcSolver algorithm. We applied the same method in 24 healthy persons aged 24 to 55 years participating in a head down tilt bedrest study. In the latter group, we also obtained direct pulse wave velocity measurements using a thigh cuff.

Results: Estimated pulse velocity very highly correlated with age (R² = 0.90) in master athletes. Estimated pulse wave velocity values were located on the same regression line like values obtained in participants of the head down tilt bed rest study. The modest correlation between estimated and measured PWV (r² 0.40; p<0.05) was attenuated after adjusting for age; the mean difference between pulse wave velocity measurements was 1 m/s.

Conclusion: Estimated pulse wave velocity mainly reflects the entered age rather than true vascular properties and, therefore, failed detecting beneficial effects of life long exercise.

Funding: The AGBRESA-Study was funded by the German Aerospace Center (DLR), the European Space Agency (ESA, contract number 4000113871/15/NL/PG) and the National Aeronautics and Space Administration (NASA, contract number 80JSC018P0078). FH received funding by the DLR and the German Federal Ministry of Economy and Technology, BMWi (50WB1816). SM, JT and JJ were supported by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology, BMK (SPACE4ALL Project, FFG No. 866761).

Effects of Resistance Training in Muscle Mass and Markers of Muscle Damage in Adults with Down Syndrome

Recent studies have emphasized that regular exercise should be encouraged as a key part of care and support for people with Down syndrome (DS). However, muscle hypotonia has traditionally been considered a major barrier to resistance training (RT) in people with DS. The main objective of this study was to analyze the impact of circuit RT on markers of muscle damage. The secondary objective was to assess the influence of a RT program on body composition and work task performance. Thirty-six men with DS were recruited and randomly assigned to perform a circuit RT program with six stations 3 days/week for 12 weeks (n = 18) or to a control group (n = 18). Body composition was assessed by bioelectrical impedance analysis. Serum markers of muscle damage (creatine kinase, myoglobin, and lactate dehydrogenase) were determined at baseline and at the end of training weeks 1, 6, and 12. Work task performance was assessed using the weighted pail-carry test. RT did not induce significant changes in markers of muscle damage during the intervention. Furthermore, muscle mass and work task performance were significantly improved in the exercise group. These findings suggest that circuit RT can be used safely to increase muscle mass and work task performance in young adults with DS. Muscle hypotonia should not be considered a major barrier to exercise in people with DS, provided that qualified staff design and supervise all training sessions.

Sex differences for predicting metabolic syndrome by adipose dysfunction markers in institutionalized elderly

AIMS

Recent studies have emphasized that metabolic syndrome (MetS) was the most important modifiable risk factor for cardiovascular and cerebrovascular diseases in the institutionalized elderly. In addition, the occurrence of MetS was higher in those with longer age-adjusted institutionalization time. The present study was conducted to assess predictive value of markers of adipose tissue dysfunction for the early screening of MetS in this population.

METHODS AND RESULTS

Two hundred and eleven institutionalized older adults (132 women, aged 74.3 ± 7.3 years; 79 men, aged 71.5 ± 7.3 years) were enrolled in the current cross-sectional study. Lipid accumulation product (LAP), visceral adiposity index (VAI), body adiposity index (BAI), and triglycerides (TG)/high-density lipoprotein (HDL)-cholesterol ratio were determined. The receiver operating characteristic curve was calculated to compare the area under the curve of each index. The total prevalence of MetS was 23.8%. In female group, VAI and TG/HDL ratio presented moderate-high sensitivity (77.78% and 78.38%, respectively) and specificity (77.62% and 73.49%, respectively). In males group, LAP presented moderate-high sensitivity (75%) and specificity (76.9%).

CONCLUSION

Gender played a key role on the prediction of MetS by adipose dysfunction markers in institutionalized elderly. Accordingly, VAI and TG/HDL-cholesterol ratio showed the highest predictive value for MetS in female elderly. LAP was the strongest predictor of MetS in male elderly.

Dynamical System Modeling of Self-Regulated Systems Undergoing Multiple Excitations: First Order Differential Equation Approach

This article proposes a dynamical system modeling approach for the analysis of longitudinal data of self-regulated homeostatic systems experiencing multiple excitations. It focuses on the evolution of a signal (e.g., heart rate) before, during, and after excitations taking the system out of its equilibrium (e.g., physical effort during cardiac stress testing). Such approach can be applied to a broad range of outcomes such as physiological processes in medicine and psychosocial processes in social sciences, and it allows to extract simple characteristics of the signal studied. The model is based on a first order linear differential equation with constant coefficients defined by three main parameters corresponding to the initial equilibrium value, the dynamic characteristic time, and the reaction to the excitation. Assuming the presence of interindividual variability (random effects) on these three parameters, we propose a two-step procedure to estimate them. We then compare the results of this analysis to several other estimation procedures in a simulation study that clarifies under which conditions parameters are accurately estimated. Finally, applications of this model are illustrated using cardiology data recorded during effort tests.

Proposed cut-off points for anthropometric and bioelectrical measures based on overweight and obesity criteria in Spanish institutionalised elderly people

The increasing prevalence of obesity among the institutionalised elderly population and its severe consequences on health requires an early and accurate diagnosis that can be easily achieved in any clinical setting. This study aimed to determine new cut-off values for anthropometric and bioelectrical impedance measures that are superior to body mass index criteria for overweight and obesity status in a sample of Spanish institutionalised elderly population. A total of 211 institutionalised older adults (132 women, aged 84.3±7.3 years; 79 men, aged 81.5±7.3 years) were enrolled in the current cross-sectional study. Anthropometric and bioelectrical impedance measures included the body mass index, waist circumference, gluteal circumference, waist-hip ratio, sagittal-abdominal diameter, trunk fat, and visceral-fat ratio. In women, the waist circumference, gluteal circumference, sagittal-abdominal diameter, trunk fat, and visceral-fat index presented strongly significant specificity and sensitivity (area under the curve [AUC], p<0.0001) and elevated discriminative values (receiver operating characteristic [ROC] curves: 0.827 to 0.867) for overweight and obesity status. In men, the waist-hip ratio, waist circumference, gluteal circumference, sagittal-abdominal diameter, trunk fat, and visceral-fat ratio were strongly significant AUC (p<0.0001), with moderate-to-high values (ROC curves: 0.757-0.871). In conclusion, our findings suggest that gluteal circumference, waist circumference, and sagittal-abdominal diameter in women and trunk fat, visceral-fat ratio, and waist circumference in men may represent more suitable cut-off values superior to body mass index criteria for overweight and obesity in the Spanish institutionalised elderly population.

The complex relationship between effort and heart rate: a hint from dynamic analysis

OBJECTIVE

Dynamic analysis can be used to study the changes of self-regulated biological processes driven by external stimuli. Recently, the changes of heart rate during effort tests has successfully been adjusted using a simple first-order differential equation model driven by body power expenditure. Although this approach produces valid estimates and yields pertinent indices for the analysis of such measurements, it suffers from an inability to model the saturation of the heart-rate increase at high power expenditures and the change of heart-rate equilibrium following effort.

APPROACH

We propose a new analysis allowing the estimation of changes of the heart rate in response to effort (gain) as a function of the power expenditure value.

MAIN RESULTS

When applied to the measured heart rates of 30 amateur athletes performing a maximum graded-effort treadmill test, the proposed model was able to predict 99% of the heart rate change measured during exercise. The estimated gains decreased with a power increase above the first ventilatory threshold. This trend was stronger above the second ventilatory threshold and was strongly correlated with the maximum oxygen consumption.

SIGNIFICANCE

The proposed approach yields a highly precise model of heart rate dynamics during variable effort that reflects the changes of metabolic energy systems at play during exercise.

The Effects of Aquatic Plyometric Training on Repeated Jumps, Drop Jumps and Muscle Damage

The purpose of this study was to compare the effects of land- vs. aquatic based plyometric training programs on the drop jump, repeated jump performance and muscle damage. Sixty-five male students were randomly assigned to one of 3 groups: aquatic plyometric training group (APT), plyometric training group (PT) and control group (CG). Both experimental groups trained twice a week for 10 weeks performing the same number of sets and total jumps. The following variables were measured prior to, halfway through and after the training programs: creatine kinase (CK) concentration, maximal height during a drop jump from the height of 30 (DJ30) and 50 cm (DJ50), and mean height during a repeated vertical jump test (RJ). The training program resulted in a significant increase (P<0.01-0.001) in RJ, DJ30, and DJ50 for PT, whereas neither APT nor CG reached any significant improvement APT showed likely/possibly improvements on DJ30 and DJ50, respectively. Greater intra-group Effect Size in CK was found for PT when compared to APT. In conclusion, although APT seems to be a safe alternative method for reducing the stress produced on the musculoskeletal system by plyometric training, PT produced greater gains on reactive jumps performance than APT.

Salivary testosterone and immunoglobulin A were increased by resistance training in adults with Down syndrome

This study was designed to assess the influence of resistance training on salivary immunoglobulin A (IgA) levels and hormone profile in sedentary adults with Down syndrome (DS). A total of 40 male adults with DS were recruited for the trial through different community support groups for people with intellectual disabilities. All participants had medical approval for participation in physical activity. Twenty-four adults were randomly assigned to perform resistance training in a circuit with six stations, 3 days per week for 12 weeks. Training intensity was based on functioning in the eight-repetition maximum (8RM) test for each exercise. The control group included 16 age-, gender-, and BMI-matched adults with DS. Salivary IgA, testosterone, and cortisol levels were measured by ELISA. Work task performance was assessed using the repetitive weighted-box-stacking test. Resistance training significantly increased salivary IgA concentration (P=0.0120; d=0.94) and testosterone levels (P=0.0088; d=1.57) in the exercising group. Furthermore, it also improved work task performance. No changes were seen in the controls who had not exercised. In conclusion, a short-term resistance training protocol improved mucosal immunity response as well as salivary testosterone levels in sedentary adults with DS.