Square-stepping exercise in older inpatients in early geriatric rehabilitation. A randomized controlled pilot study.

BACKGROUND: Preservation of mobility and fall prevention have a high priority in geriatric rehabilitation. Square-Stepping Exercise (SSE) as an evaluated and standardized program has been proven to be an effective training for older people in the community setting to reduce falls and improve subjectively perceived health status. This randomized controlled trial (RCT), for the first time, examines SSE in the context of inpatient early geriatric rehabilitation compared to conventional physiotherapy (cPT). METHODS: Data were collected in a general hospital in the department of acute geriatric care at admission and discharge. Fifty-eight inpatients were randomized to control (CG, n = 29) or intervention groups (IG, n = 29). CG received usual care with cPT five days per week during their hospital stay. For the IG SSE replaced cPT for at least six sessions, alternating with cPT. Physical function was measured with the Short Physical Performance Battery (SPPB) and Timed "Up & Go" (TUG). Gait speed was measured over a distance of 10 m. In a subgroup (n = 17) spatiotemporal gait parameters were analyzed via a GAITRite® system. RESULTS: Both the SPPB total score improved significantly (p = < 0.001) from baseline to discharge in both groups, as did the TUG (p < 0.001). In the SPPB Chair Rise both groups improved with a significant group difference in favor of the IG (p = 0.031). For both groups gait characteristics improved: Gait speed (p = < 0.001), walk ratio (p = 0.011), step length (p = < 0.001), stride length (p = < 0.001) and double support (p = 0.009). For step length at maximum gait speed (p = 0.054) and stride length at maximum gait speed (p = 0.060) a trend in favor of the IG was visible. CONCLUSIONS: SSE in combination with a reduced number of sessions of cPT is as effective as cPT for inpatients in early geriatric rehabilitation to increase physical function and gait characteristics. In the Chair Rise test SSE appears to be superior. These results highlight that SSE is effective, and may serve as an additional component for cPT for older adults requiring geriatric acute care. TRIAL REGISTRATION: DRKS00026191.

Impaired Standing Balance in Older Adults with Cognitive Impairment After a Severe Fall.

Introduction Fall-related sequelae as well as balance and gait impairments are more pronounced in older adults, who are cognitively impaired (OACI) compared to older adults who are cognitively healthy (OACH). Evidence is scarce about differences in standing balance and gait in OACH and OACI after a fall, even though these are major risks for recurrent falls. Thus, the aim of the study was to investigate early impairments in gait and balance, by adding Inertial Measurement Units (IMUs) to a functional performance test in OACH and OACI after a severe fall with presentation to the emergency department (ED) and immediate discharge. Methods The study sample was stratified into participants with and without probable cognitive impairment using the result of the Montreal Cognitive Assessment total score (maximum of 30 points). The cutoff for probable cognitive impairment was set at ≤ 24. Standing balance and gait parameters were measured using three IMUs in n=69 OACH (72.0 ± 8.2 years) and n=76 OACI (78.7 ± 8.1 years). Data were collected at participants' homes as part of a comprehensive geriatric assessment in the "SeFallED" study within four weeks after presentation to the ED after a severe fall (German Clinical Trials Register ID: 00025949). ANCOVA was used for statistical analysis, adjusted for age. Results The data indicated significantly more sway for OACI compared to OACH during balance tasks, whereas no differences in gait behavior were found. In detail, differences in standing balance were revealed for mean velocity (m/s) during parallel stance with eyes open (ηp2=0.190, p<0.001) and eyes closed on a balance cushion (ηp2=0.059, p=0.029), as well as during tandem stance (ηp2=0.034, p=0.044) between OACI and OACH. Further differences between the two groups were detected for path length (m/s2) during parallel stance with eyes open (ηp2=0.144, p<0.001) and eyes closed (ηp2=0.044, p<0.027) and for range (m/s2) during tandem (ηp2=0.036, p=0.036) and parallel stance with eyes closed (ηp2= 0.045, p=0.032). Conclusion Even though both groups have experienced a severe fall with presentation to the ED in the preceding 4 weeks, balance control among OACI indicated a higher fall risk than among OACH. Therefore, effective secondary falls prevention efforts have to be established, particularly for OACI.

Recruiting patients for falls prevention in the emergency department - worth the challenge.

BACKGROUND: Severe falls escalate the risk of future falls and functional decline as indicated by recent global guidelines. To establish effective falls prevention, individuals at highest risk must be thoroughly studied and, therefore, successfully recruited. OBJECTIVE: Recruiting from an emergency department (ED) may mitigate common selection biases, such as overrepresentation of individuals with a higher social status and healthier lifestyle. However, this approach presents unique challenges due to ED-specific conditions. Hence, we present the successes and challenges of an ED-based recruitment for an observational study. METHODS: The SeFallED study targets older adults aged ≥60 years, who present to either of two hospitals in Oldenburg after a fall without subsequent admission. A study nurse addressed individuals in the EDs. Subsequently, potential participants were contacted by phone to arrange a home visit for obtaining written consent. Data of participants were compared with total admissions during the recruitment period to determine recruitment rate and compare patients' characteristics. RESULTS: Over 1.500 individuals met the inclusion criteria. Of these, 288 participants were successfully recruited. Most patients presented to the ED outside of the study team's working hours, and some opted not to participate (main reason: too unwell (40%)). Compared to working hours, a participant was recruited every 14 h. Comparing characteristics, a trend towards better health and younger age was observed. CONCLUSION: ED-based recruitment offers the opportunity to include more diverse individuals in falls prevention. To achieve adequate sample sizes, flexibility in working days and hours of the research team are obligatory. TRIAL REGISTRATION: DRKS00025949.

Depth-Imaging for Gait Analysis on a Treadmill in Older Adults at Risk of Falling.

BACKGROUND: Accidental falls are a major health issue in older people. One significant and potentially modifiable risk factor is reduced gait stability. Clinicians do not have sophisticated kinematic options to measure this risk factor with simple and affordable systems. Depth-imaging with AI-pose estimation can be used for gait analysis in young healthy adults. However, is it applicable for measuring gait in older adults at a risk of falling? METHODS: In this methodological comparison 59 older adults with and without a history of falls walked on a treadmill while their gait pattern was recorded with multiple inertial measurement units and with an Azure Kinect depth-camera. Spatiotemporal gait parameters of both systems were compared for convergent validity and with a Bland-Altman plot. RESULTS: Correlation between systems for stride length (r=.992, [Formula: see text]) and stride time (r=0.914, [Formula: see text]) was high. Bland-Altman plots revealed a moderate agreement in stride length (-0.74 ± 3.68 cm; [-7.96 cm to 6.47 cm]) and stride time (-3.7±54 ms; [-109 ms to 102 ms]). CONCLUSION: Gait parameters in older adults with and without a history of falls can be measured with inertial measurement units and Azure Kinect cameras. Affordable and small depth-cameras agree with IMUs for gait analysis in older adults with and without an increased risk of falling. However, tolerable accuracy is limited to the average over multiple steps of spatiotemporal parameters derived from the initial foot contact. Clinical Translation Statement- Gait parameters in older adults with and without a history of falls can be measured with inertial measurement units and Azure Kinect. Affordable and small depth-cameras, developed for various purposes in research and industry, agree with IMUs in clinical gait analysis in older adults with and without an increased risk of falling. However, tolerable accuracy to assess function or monitor changes in gait is limited to the average over multiple steps of spatiotemporal parameters derived from the initial foot contact.

Leisure time physical activity and exercise performance in active older people in rural areas-Comparison of the first and second COVID-19 related lockdown in Germany.

The closure of all sports facilities during the two lockdowns in Germany favoured a reduction of leisure time physical activity during the COVID-19 pandemic. The aim of this study was to compare leisure time physical activity during the 1st and 2nd lockdown and to examine exercise performance before and after resumption of exercise. Leisure time physical activity was measured by the Longitudinal Urban Cohort Ageing Study (LUCAS) functional ability index and energy expenditure in the Minnesota Leisure Time Physical Activity Questionnaire. Participants' exercise performance was extracted from a chip-controlled fitness circuit. Differences were tested for statistical significance using Friedman tests. 35 participants above 60 years were included from the Oldenburg area (20 women, 15 men, mean age and standard deviation 71±6 years). The decline in energy expenditure was higher during the 2nd lockdown (1st lockdown: Median -55.7 kcal.day-1, Q0.25-121.3 kcal.day-1, Q0.75 132.9 kcal.day-1; 2nd lockdown: Median -119.7 kcal.day-1, Q0.25-255.6 kcal.day-1, Q0.75-65.1 kcal.day-1; Friedman test: p<0.001, n = 35, W = 0.262). The time spent in the fitness circuit decreased from lockdown to lockdown as well as the number of participants exercising there. Intense activities were performed during the two lockdowns by only 7 and 3 participants, respectively, and were not resumed by two-thirds of the participants after the 2nd lockdown. During the 1st lockdown, exercise performance on resistance exercise devices increased in most of them, while it decreased by 1 to 7% during the 2nd lockdown. The lockdowns limited leisure time physical activity in older adults. This was more pronounced during the lockdown in winter 2020/2021, when participants engaged less in outdoor activities. Therefore, measures should be taken to maintain physical activity and muscle strength, especially during winter months, with a home-based training, if visiting gyms is not possible.

Comparison of machine learning approaches for near-fall-detection with motion sensors.

Introduction: Falls are one of the most common causes of emergency hospital visits in older people. Early recognition of an increased fall risk, which can be indicated by the occurrence of near-falls, is important to initiate interventions. Methods: In a study with 87 subjects we simulated near-fall events on a perturbation treadmill and recorded them with inertial measurement units (IMU) at seven different positions. We investigated different machine learning models for the near-fall detection including support vector machines, AdaBoost, convolutional neural networks, and bidirectional long short-term memory networks. Additionally, we analyzed the influence of the sensor position on the classification results. Results: The best results showed a DeepConvLSTM with an F1 score of 0.954 (precision 0.969, recall 0.942) at the sensor position "left wrist." Discussion: Since these results were obtained in the laboratory, the next step is to evaluate the suitability of the classifiers in the field.

Physical performance and compensation strategies of older adults to maintain physical fitness and well-being during the COVID-19 pandemic in Germany.

INTRODUCTION: During the first wave of the COVID-19 pandemic in March 2020, worldwide restrictions in social life, including the closure of sport facilities, led to a reduction of physical activity and subjective well-being. The aim of this study is to describe physical training habits, and subjective well-being in relation to objective training data from a chip-controlled fitness circuit in the rural area of Oldenburg, Germany. MATERIALS AND METHODS: Overall, 35 older adults (20 women 71 ± 6 y/o and 15 men, 72 ± 7 y/o), regularly exercising in a chip-controlled fitness circuit before the lockdown in March 2020, were interviewed. The training data from February to August 2020 from six strength and two endurance exercise devices were extracted and compared to data before and up to three months after the lockdown. Additionally, participants' personal characteristics, physical activities and quality of life before, during, and after the first lockdown were assessed. RESULTS: The leg score (pre, postJune, postJuly, postAugust: 1207 ± 469 kg, 1248 ± 477 kg, 1254 ± 516 kg, 1283 ± 493 kg; p = 0.137) and endurance scores (ergometer: 0.93 ± 0.35 min- 1 · watt- 1, 0.86 ± 0.31 min- 1 · watt- 1, 0.86 ± 0.31 min- 1 · watt- 1, 0.85 ± 0.28 min- 1 · watt- 1 ; p = 0.442) were not significantly different, in contrast to the rowing score (1426 ± 582 kg, 1558 ± 704 kg, 1630 ± 757 kg, 1680 ± 837 kg; p < 0.001). A significant increase of total energy expenditure (p = 0.026), mainly through gardening, walking, and bike riding was observed. The greatest personal limitation reported, was the loss of social contacts. CONCLUSION: The presented data did not show a decrease in training performance, but a slight trend towards an increase. A compensatory increase in regular outdoor activities seems to have a protective effect against a loss of training performance and may have the potential to stabilize subjective well-being during lockdown periods.

The impact of pandemic-related social distancing regulations on exercise performance-Objective data and training recommendations to mitigate losses in physical fitness.

Introduction: In the context of the COVID-19 pandemic in Germany, governmental restrictions led to the closure of sports facilities for several months. To date, only subjective and fitness-tracking related data on physical activity during the pandemic are available. Using data of a chip-controlled fitness circuit, training data as a measure of physical performance before and after the lockdown during the first wave of the COVID-19 pandemic will show the impact of the training interruption on exercise performance in middle-aged and older adults. The re-training data are analyzed, to extract practical recommendations. Methods: Objective training data of 17,450 participants [11,097 middle-aged (45-64 yrs), 6,353 older (≥65 yrs)] were exported from chip-controlled milon® fitness circuit systems before and after the first COVID-19 related lockdown in Germany. The change in the product of training weight (sum of lifting and lowering the training weight) and repetitions on the leg extension resistance exercise device (leg score) between the last three training sessions before the lockdown and the first ten training sessions after individual training resumption as well as the last training session before the second lockdown in October 2020 was analyzed. Results: Participants who trained with high intensity before the lockdown, experienced deleterious effects of the training interruption (middle-aged group: -218 kg, older group: ~-230.8 kg; p < 0.001 for change in leg score from to post-lockdown) with no age effect. Participants training with a leg score of more than 3,000 kg did not resume their leg score until the second lockdown. Conclusion: The interruption of training in a fitness circuit with combined resistance and endurance training due to the lockdown affected mainly those participants who trained at high intensity. Apparently, high-intensity training could not be compensated by home-based training or outdoor activities. Concepts for high-intensity resistance training during closure of sports facilities are needed to be prepared for future periods of high incidence rates of infectious diseases, while especially vulnerable people feel uncomfortable to visit sports facilities. Trial registration: Identifier, DRKS00022433.

Short-term isolation effects on the brain, cognitive performance, and sleep-The role of exercise.

Isolation is stressful and negatively affects sleep and mood and might also affect the structure and function of the brain. Physical exercise improves brain function. We investigated the influence of physical exercise during isolation on sleep, affect, and neurobehavioral function. N = 16 were isolated for 30 days with daily exercise routines (ISO100) and n = 16 isolated for 45 days with every second day exercise (ISO50). N = 27 were non-isolated controls who either exercised on a daily basis (CTRLEx) or refused exercise (CTRLNonEx) for 30 days. At the beginning and the end of each intervention, intravenous morning cortisol, melatonin, brain-derived neurotrophic factor and IGF-1, positive and negative affect scales, electroencephalography, cognitive function, and sleep patterns (actigraphy) were assessed. High levels of cortisol were observed for the isolated groups (p < .05) without negative effects on the brain, cognitive function, sleep, and mood after 4 to 6 weeks of isolation, where physical exercise was performed regularly. An increase in cortisol and impairments of sleep quality, mood, cognitive function, and neurotrophic factors (p < .05) were observed after 4 weeks of absence of physical exercise in the CTRLNonEx group. These findings raise the assumption that regular physical exercise routines are a key component during isolation to maintain brain health and function.

Sentinel fall presenting to the emergency department (SeFallED) - protocol of a complex study including long-term observation of functional trajectories after a fall, exploration of specific fall risk factors, and patients' views on falls prevention.

BACKGROUND: Falls are a leading cause for emergency department (ED) visits in older adults. As a fall is associated with a high risk of functional decline and further falls and many falls do not receive medical attention, the ED is ideal to initiate secondary prevention, an opportunity generally not taken. Data on trajectories to identify patients, who would profit the most form early intervention and to examine the impact of a fall event, are lacking. To tailor interventions to the individual's needs and preferences, and to address the whole scope of fall risks, we developed this longitudinal study using an extensive assessment battery including dynamic balance and aerobic fitness, but also sensor-based data. Additionally, participative research will contribute valuable qualitative data, and machine learning will be used to identify trips, slips, and falls in sensor data during daily life. METHODS: This is a mixed-methods study consisting of four parts: (1) an observational prospective study, (2) a randomized controlled trial (RCT) to explore whether a diagnostic to measure reactive dynamic balance influences fall risk, (3) machine learning approaches and (4) a qualitative study to explore patients' and their caregivers' views. We will target a sample size of 450 adults of 60 years and older, who presented to the ED of the Klinikum Oldenburg after a fall and are not hospitalized. The participants will be followed up over 24 months (within four weeks after the ED, after 6, 12 and 24 months). We will assess functional abilities, fall risk factors, participation, quality of life, falls incidence, and physical activity using validated instruments, including sensor-data. Additionally, two thirds of the patients will undergo intensive testing in the gait laboratory and 72 participants will partake in focus group interviews. DISCUSSION: The results of the SeFallED study will be used to identify risk factors with high predictive value for functional outcome after a sentinel fall. This will help to (1) establish a protocol adapted to the situation in the ED to identify patients at risk and (2) to initiate an appropriate care pathway, which will be developed based on the results of this study. TRIAL REGISTRATION: DRKS (Deutsches Register für klinische Studien, DRKS00025949 ). Prospectively registered on 4th November, 2021.

Cardiovascular Regulation During Acute Gravitational Changes with Exhaling on Exertion.

During gravitational changes or changes in the direction of action in relation to the body, fluid displacements can be observed. In special cases different breathing maneuvers (e. g., exhaling on exertion; Ex-Ex) are used to counteract acute fluid shifts. Both factors have a significant impact on cardiovascular regulation. Eight healthy male subjects were tested on a tilt seat, long arm human centrifuge, and parabolic flight. The work aims to investigate the effect of exhaling on exertion on the cardiovascular regulation during acute gravitational changes compared to normal breathing. Possible interactions and differences between conditions (Ex-Ex, normal breathing) for the parameters V'O 2 , V' E , HR, and SV were analysed over a 40 s period by a three-way ANOVA. Significant (p≤0.05) effects for all main factors and interactions between condition and time as well as maneuver and time were found for all variables. The exhaling on exertion maneuver had a significant influence on the cardiovascular response during acute gravitational and positional changes. For example, the significant increase of V'O2 at the end of the exhalation on exertion maneuver indicates an increased lung circulation as a result of the maneuver.

Cardiorespiratory kinetics in exercise physiology: estimates and predictions using randomized changes in work rate.

PURPOSE: Kinetics of cardiorespiratory parameters (CRP) in response to work rate (WR) changes are evaluated by pseudo-random binary sequences (PRBS testing). In this study, two algorithms were applied to convert responses from PRBS testing into appropriate impulse responses to predict steady states values and responses to incremental increases in exercise intensity. METHODS: 13 individuals (age: 41 ± 9 years, BMI: 23.8 ± 3.7 kg m-2), completing an exercise test protocol, comprising a section of randomized changes of 30 W and 80 W (PRBS), two phases of constant WR at 30 W and 80 W and incremental WR until subjective fatigue, were included in the analysis. Ventilation ([Formula: see text]), O2 uptake ([Formula: see text]), CO2 output ([Formula: see text]) and heart rate (HR) were monitored. Impulse responses were calculated in the time domain and in the frequency domain from the cross-correlations of WR and the respective CRP. RESULTS: The algorithm in the time domain allows better prediction for [Formula: see text] and [Formula: see text], whereas for [Formula: see text] and HR the results were similar for both algorithms. Best predictions were found for [Formula: see text] and HR with higher (3-4%) 30 W steady states and lower (1-4%) values for 80 W. Tendencies were found in the residuals between predicted and measured data. CONCLUSION: The CRP kinetics, resulting from PRBS testing, are qualified to assess steady states within the applied WR range. Below the ventilatory threshold, [Formula: see text] and HR responses to incrementally increasing exercise intensities can be sufficiently predicted.

Confinement, partial sleep deprivation and defined physical activity-influence on cardiorespiratory regulation and capacity.

INTRODUCTION: Adequate cardiorespiratory fitness is of utmost importance during spaceflight and should be assessable via moderate work rate intensities, e.g., using kinetics parameters. The combination of restricted sleep, and defined physical exercise during a 45-day simulated space mission is expected to slow heart rate (HR) kinetics without changes in oxygen uptake ([Formula: see text]) kinetics. METHODS: Overall, 14 crew members (9 males, 5 females, 37 ± 7 yrs, 23.4 ± 3.5 kg m-2) simulated a 45-d-mission to an asteroid. During the mission, the sleep schedule included 5 nights of 5 h and 2 nights of 8 h sleep. The crew members were tested on a cycle ergometer, using pseudo-random binary sequences, changing between 30 and 80 W on day 8 before (MD-8), day 22 (MD22) and 42 (MD42) after the beginning and day 4 (MD + 4) following the end of the mission. Kinetics information was assessed using the maxima of cross-correlation functions (CCFmax). Higher CCFmax indicates faster responses. RESULTS: CCFmax(HR) was significantly (p = 0.008) slower at MD-8 (0.30 ± 0.06) compared with MD22 (0.36 ± 0.06), MD42 (0.38 ± 0.06) and MD + 4 (0.35 ± 0.06). Mean HR values during the different work rate steps were higher at MD-8 and MD + 4 compared to MD22 and MD42 (p < 0.001). DISCUSSION: The physical training during the mission accelerated HR kinetics, but had no impact on mean HR values post mission. Thus, HR kinetics seem to be sensitive to changes in cardiorespiratory fitness and may be a valuable parameter to monitor fitness. Kinetics and capacities adapt independently in response to confinement in combination with defined physical activity and sleep.

[Feasibility and acceptance of video-based physiotherapy : New medical care provision for older people during the COVID-19 pandemic]. / Machbarkeit und Akzeptanz videobasierter Physiotherapie : Neues Versorgungsangebot für ältere Menschen während der COVID-19-Pandemie.

BACKGROUND AND OBJECTIVE: Restrictions in public life during the COVID-19 pandemic mainly addressed the safety of high-risk older multimorbid patients to protect them from infection. Nevertheless, detrimental aspects of the lockdown for older people are a reduction in physical activity and limited access to physiotherapy, which are likely to have a negative impact on the health status. This study examined the feasibility of video-based physiotherapy (VT) and the subjective rating of VT by patients and therapists. METHODS: From April to June 2020, 4 facilities with 9 patients (6 women, 64-82 years old) participated in the study and were provided with technical equipment. Semistructured telephone interviews were conducted in eight patients to assess physical activity, functional ability and participation before and during the restrictions. Both patients and therapists were asked about their subjective experiences with VT. RESULTS: A total of 92 VT sessions took place. Performance of the exercises and comprehension of instructions were rated as good to very good. The level of acceptance was high. Of the patients four described a perceived reduction in their physical activities due to the public restrictions; however, in the questionnaires no substantial differences in participation and physical activity were found. DISCUSSION: The use of VT is feasible in older patients. Only minor technical support is needed. In pandemic situations or in other contexts VT appears to be a promising supplement or alternative to normal physiotherapy. Further studies are needed to identify suitable patient groups, to prove efficacy and to develop further content-related aspects of VT.

Time-series analysis of heart rate and blood pressure in response to changes in work rate before and after 60 days of 6° head down tilt bed rest.

PURPOSE: Cardiovascular regulation during exercise, described using time series analysis, is expected to be attenuated after bed rest (BR) and this effect will be dampened by a reactive jumps countermeasure. METHODS: Twenty subjects (29 ± 6 years, 23.6 ± 1.7 kg m-2) were tested on a cycle ergometer 9 days (BDC-9) before the beginning of BR as well as 2 (R + 2) and 13 days (R + 13) after the end of BR, applying moderate pseudo-random binary (PRBS) work rate changes. Heart rate (HR) and mean arterial blood pressure (mBP) were measured beat-to-beat and interpolated to 1 s intervals. HR and mBP were cross-correlated [CCF(HR-mBP)] during the PRBS. Eleven subjects participated in a reactive jump countermeasure (JUMP) during the BR period, the other part of the group served as control group (CTRL). RESULTS: In the CTRL group, significantly lower CCF(HR-mBP) values during BDC-9 were observed compared to R + 2 during the lags 20-25 s and significantly higher values during the lags - 39 s to - 35 s. In the JUMP group, significantly lower CCFs were only observed at R + 2 compared with BDC-9 during the lags 23 s and 24 s, whereas the CCFs for BDC-9 were significantly higher at several lags compared with R + 13. CONCLUSION: Attenuations in the regulation of the cardiovascular system during cycling exercise after BR were found in the CTRL group of the RSL study. Cardiovascular regulation in the JUMP group was improved compared to values before the beginning of BR, suggesting the effectiveness of the reactive jumps countermeasure to mitigate the deleterious effects of prolonged BR.

Relationship between maximal aerobic power with aerobic fitness as a function of signal-to-noise ratio.

Efforts to better understand cardiorespiratory health are relevant for the future development of optimized physical activity programs. We aimed to explore the impact of the signal quality on the expected associations between the ability of the aerobic system in supplying energy as fast as possible during moderate exercise transitions with its maximum capacity to supply energy during maximal exertion. It was hypothesized that a slower aerobic system response during moderate exercise transitions is associated with a lower maximal aerobic power; however, this relationship relies on the quality of the oxygen uptake data set. Forty-three apparently healthy participants performed a moderate constant work rate (CWR) followed by a pseudorandom binary sequence (PRBS) exercise protocol on a cycle ergometer. Participants also performed a maximum incremental cardiopulmonary exercise testing (CPET). The maximal aerobic power was evaluated by the peak oxygen uptake during the CPET, and the aerobic fitness was estimated from different approaches for oxygen uptake dynamics analysis during the CWR and PRBS protocols at different levels of signal-to-noise ratio. The product moment correlation coefficient was used to evaluate the correlation level between variables. Aerobic fitness was correlated with maximum aerobic power, but this correlation increased as a function of the signal-to-noise ratio. Aerobic fitness is related to maximal aerobic power; however, this association appeared to be highly dependent on the data quality and analysis for aerobic fitness evaluation. Our results show that simpler moderate exercise protocols might be as good as maximal exertion exercise protocols to obtain indexes related to cardiorespiratory health.NEW & NOTEWORTHY Optimized methods for cardiorespiratory health evaluation are of great interest for public health. Moderate exercise protocols might be as good as maximum exertion exercise protocols to evaluate cardiorespiratory health. Pseudorandom or constant workload moderate exercise can be used to evaluate cardiorespiratory health.

Breath-by-breath oxygen uptake during running: Effects of different calculation algorithms.

NEW FINDINGS: What is the central question of this study? Breath-by-breath gas exchange analysis during treadmill exercise can be disturbed by different breathing patterns depending on cadence, and the flow sensor might be subjected to variable mechanical stress. It is still unclear whether the outcomes of the gas exchange algorithms can be affected by running at different speeds. What is the main finding and its importance? Practically, the three investigated breath-by-breath algorithms ('Wessel', 'expiration-only' and 'independent breath') provided similar average gas exchange values for steady-state conditions. The 'independent breath' algorithm showed the lowest breath-by-breath fluctuations in the gas exchange data compared with the other investigated algorithms, both at steady state and during incremental exercise. ABSTRACT: Recently, a new breath-by-breath gas exchange calculation algorithm (called 'independent breath') was proposed. In the present work, we aimed to compare the breath-by-breath O2 uptake ( V̇O2 ) values assessed in healthy subjects undergoing a running protocol, as calculated applying the 'independent breath' algorithm or two other commonly used algorithms. The traces of respiratory flow, O2 and CO2 fractions, used by the calculation algorithms, were acquired at the mouth on 17 volunteers at rest, during running on a treadmill at 6.5 and 9.5 km h-1 , and thereafter up to volitional fatigue. Within-subject averages and standard deviations of breath-by-breath V̇O2 were calculated for steady-state conditions; the V̇O2 data of the incremental phase were analysed by means of linear regression, and their root mean square was assumed to be an index of the breath-by-breath fluctuations. The average values obtained with the different algorithms were significantly different (P < 0.001); nevertheless, from a practical point of view the difference could be considered 'small' in all the investigated conditions (effect size <0.3). The standard deviations were significantly lower for the 'independent breath' algorithm (post hoc contrasts, P < 0.001), and the slopes of the relationships with the corresponding data yielded by the other algorithms were <0.70. The root mean squares of the linear regressions calculated for the incremental phase were also significantly lower for the 'independent breath' algorithm, and the slopes of the regression lines with the corresponding values obtained with the other algorithms were <0.84. In conclusion, the 'independent breath' algorithm yielded the least breath-by-breath O2 uptake fluctuation, both during steady-state exercise and during incremental running.

Adaptation of Systemic and Pulmonary Circulation to Acute Changes in Gravity and Body Position.

INTRODUCTION: Changes in gravity or body position provoke changes in hydrostatic pressure in the arterial system and in venous return. Potential asymmetries between left (QLV) and right ventricular (QRV) cardiac output during transient gravity changes were investigated. It was hypothesized that blood volume is temporarily stored in the pulmonary vessels, with amount and duration depending on the level and directions of gravity.METHODS: Eight healthy, male subjects (32 ± 3 yr, 182 ± 7 cm, 82 ± 6 kg) were tested on a tilt seat (TS), in a long arm human centrifuge (laHC), and during parabolic flights (PF). The gravitational changes during PF were reconstructed by changing gravity in a laHC and different body positions on a TS. All participants were tested in the seated, resting position. Heart rate and blood pressure were recorded continuously and QLV was calculated, applying the Modelflow Algorithm. Gas exchange was measured breath-by-breath. QRV was calculated from these data according to the Fick Principle. Four sequences were superimposed and analyzed by ANOVA with the factors Time, Ventricle (QRV, QLV), and Mode (TS, PF, laHC).RESULTS: After reductions in gravity QRV and QLV were transiently desynchronized. ANOVA showed no main effect for Mode, but significant changes were found for Time and Ventricle and all interactions.DISCUSSION: Phases of reduced gravity seem to lead to transiently increased storage of blood volume inside the pulmonary vascular system. A more detailed understanding of these mechanisms might help to describe the compliance of the pulmonary vascular system in diseases of the pulmonary circulation.Hoffmann U, Koschate J, Appell Coriolano H-J, Drescher U, Thieschäfer L, Dumitrescu D, Werner A. Adaptation of systemic and pulmonary circulation to acute changes in gravity and body position. Aerosp Med Hum Perform. 2019; 90(8):688-695.

Cardiorespiratory kinetics: comparisons between athletes with different training habits.

PURPOSE: Fast muscular oxygen uptake ([Formula: see text]) kinetics are limiting factors for high exercise capacities. It is hypothesized that [Formula: see text] and heart rate (HR) kinetics would be faster in individuals, performing long-distance endurance training (CONT) compared with athletes performing predominantly interval-based sports (INT). METHODS: 17 subjects (INT: n = 7, 24 ± 5 years, 183 ± 7 cm, 85 ± 10 kg, 6 ± 3 h of training per week, CONT: n = 10, 37 ± 7 years, 175 ± 9 cm, 69 ± 10 kg, 6 ± 3 h of training per week) completed a treadmill work rate (WR) protocol with pseudo-randomized WR changes with velocities of 6.5 and 9.5 km h-1. [Formula: see text]O2musc and the respective kinetics were estimated from the measured pulmonary oxygen uptake and HR combined with a circulatory model. Kinetics information were calculated using time series analysis. Higher maxima of the cross-correlation function (CCF) of WR and the respective parameter ([Formula: see text], HR) indicate faster kinetics responses. RESULTS: The kinetics of HR (INT: 0.23 ± 0.04 vs. CONT: 0.42 ± 0.18; P = 0.001), [Formula: see text]O2pulm (0.30 ± 0.05 vs. 0.53 ± 0.20; P = 0.005) and [Formula: see text]O2musc (0.31 ± 0.06 vs. 0.53 ± 0.16; P = 0.005) were significantly slower in INT compared with the CONT athletes. CONCLUSIONS: It seems that at least in the long-term CONT exercise, training without the need of changing intensities is favorable for fast [Formula: see text]O2 and HR kinetics compared with INT exercise including frequently changing intensities.