Reinforcement learning informs optimal treatment strategies to limit antibiotic resistance.

Antimicrobial resistance was estimated to be associated with 4.95 million deaths worldwide in 2019. It is possible to frame the antimicrobial resistance problem as a feedback-control problem. If we could optimize this feedback-control problem and translate our findings to the clinic, we could slow, prevent, or reverse the development of high-level drug resistance. Prior work on this topic has relied on systems where the exact dynamics and parameters were known a priori. In this study, we extend this work using a reinforcement learning (RL) approach capable of learning effective drug cycling policies in a system defined by empirically measured fitness landscapes. Crucially, we show that it is possible to learn effective drug cycling policies despite the problems of noisy, limited, or delayed measurement. Given access to a panel of 15 [Formula: see text]-lactam antibiotics with which to treat the simulated Escherichia coli population, we demonstrate that RL agents outperform two naive treatment paradigms at minimizing the population fitness over time. We also show that RL agents approach the performance of the optimal drug cycling policy. Even when stochastic noise is introduced to the measurements of population fitness, we show that RL agents are capable of maintaining evolving populations at lower growth rates compared to controls. We further tested our approach in arbitrary fitness landscapes of up to 1,024 genotypes. We show that minimization of population fitness using drug cycles is not limited by increasing genome size. Our work represents a proof-of-concept for using AI to control complex evolutionary processes.

Effects of 1,144 km of road cycling performed in 7 days: a cardiometabolic imaging study.

This cardiometabolic imaging study was designed to document the adaptation of middle-aged recreational cyclists to a large exercise prescription not aiming at weight loss. Eleven middle-aged recreational male cyclists traveled 1,144 km over seven consecutive days. A comprehensive cardiometabolic profile including visceral and ectopic adiposity assessed by magnetic resonance imaging was obtained at baseline and following the exercise week. Cardiorespiratory fitness (CRF) was measured using maximal cardiopulmonary exercise testing. During the week, heart rate was monitored to calculate individual energy expenditure. Baseline characteristics of cyclists were compared with 86 healthy males in the same age range. Cyclists presented higher baseline CRF (+9.2 mL/kg/min, P < 0.0001) and lower subcutaneous (-56.2 mL, P < 0.05) and liver (-3.3%, P < 0.05) fat compared with the reference group. Despite the large energy expenditure during the cycling week, the increase in energy intake limited decreases in body weight (-0.8 ± 0.9 kg, P < 0.05) and body mass index (-0.3 ± 0.3 kg/m2, P < 0.05). Loss of fat mass (-1.5 ± 1.0 kg, P < 0.001) and a trend toward an increased lean mass (+0.8 ± 1.2 kg, P < 0.07) were observed. Visceral adiposity (-14.1 ± 14.2 mL, P < 0.01) and waist circumference (-3.2 ± 1.7 cm, P < 0.0001) decreased, whereas subcutaneous (-2.7 ± 5.1 mL, NS), liver (-0.5 ± 0.9%, NS), and cardiac (-0.3 ± 2.3 mL, NS) fat remained unchanged. This cardiometabolic imaging study documents middle-aged recreational cyclists' subcutaneous and visceral adiposity as well as cardiac and liver fat responses to a large volume of endurance exercise despite an increase in energy intake aimed at limiting weight loss.NEW & NOTEWORTHY Even when being accompanied by a substantial increase in energy intake to compensate energy expenditure and limit weight loss, a large volume of endurance exercise performed within a short period of time is associated with a significant reduction in visceral adiposity. High cardiorespiratory fitness is associated with low levels of liver fat in middle-aged males.

Acute partial sleep deprivation attenuates blood pressure responses to cycling exercise.

Exaggerated blood pressure (BP) responses during exercise are independently associated with future development of hypertension. Partial sleep deprivation (PSD) can increase 24-h ambulatory BP, but the effects on exercise BP are unclear. We hypothesized that acute PSD would augment the BP response to constant load cycling exercise and a 20-min time trial. Twenty-two healthy adults (22 ± 3 yr old; 13 males; V̇o2peak, 43.6 ± 8.2 mL·kg-1·min-1) completed a randomized crossover trial in which they either slept normally (normal sleep-wake schedule for each participant) or sleep was partially deprived (early awakening, 40% of normal sleep duration). Each participant completed a 12-min warm-up consisting of two 6-min steps (step 1, 62 ± 25 W; step 2, 137 ± 60 W) followed by a 20-min time trial on a cycle ergometer. PSD did not alter power output during the 20-min time trial [(control vs. PSD) 170 ± 68 vs. 168 ± 68 W, P = 0.65]. Systolic BP did not differ during step 1 of the warm-up (141 ± 15 vs. 137 ± 12 mmHg, P = 0.39) but was lower following PSD during step 2 (165 ± 21 vs. 159 ± 22 mmHg, P = 0.004) and the 20-min time trial (171 ± 20 vs. 164 ± 23 mmHg, P < 0.001). These results were maintained when peak oxygen uptake (V̇o2peak) was included as a covariate. Systolic BP responses were modulated by sex (time × visit × sex interaction P = 0.03), with attenuated systolic BP during the warm-up and the 20-min time trial in males but not in females. In contrast to our hypothesis, acute PSD attenuates systolic BP responses during constant load and 20-min time trial cycling exercise; however, these observations appear to be primarily driven by changes in males.NEW & NOTEWORTHY A single night of partial sleep deprivation (PSD) can increase ambulatory blood pressure (BP) the following day. Despite this phenomenon, the present study found that acute PSD attenuates systolic BP responses to both constant load cycling and a 20-min cycling time trial in young healthy adults. Interestingly, the attenuated systolic BP responses following PSD appeared to be modulated by sex such that attenuations were observed in males but not in females.

Performance and perceived fatigability across the intensity spectrum: role of muscle mass during cycling.

The role of muscle mass in modulating performance and perceived fatigability across the entire intensity spectrum during cycling remains unexplored. We hypothesized that at task failure (Tlim), muscle contractile function would decline more following single- (SL) versus double-leg (DL) cycling within severe and extreme intensities, but not moderate and heavy intensities. After DL and SL ramp-incremental tests, on separate days, 11 recreationally active males (V̇o2max: 49.5 ± 7.7 mL·kg-1·min-1) completed SL and DL cycling until Tlim within each intensity domain. Power output for SL trials was set at 60% of the corresponding DL trial. Before and immediately after Tlim, participants performed an isometric maximal voluntary contraction (MVC) coupled with one superimposed and three resting femoral nerve stimulations [100 Hz; 10 Hz; single twitch (Qtw)] to measure performance fatigability. Perceived fatigue, leg pain, dyspnea, and effort were collected during trials. Tlim within each intensity domain was not different between SL and DL (all P > 0.05). MVC declined more for SL versus DL following heavy- (-42 ± 16% vs. -30 ± 18%; P = 0.011) and severe-intensity cycling (-41 ± 12% vs. -31 ± 15%; P = 0.036). Similarly, peak Qtw force declined more for SL following heavy- (-31 ± 12% vs. -22 ± 10%; P = 0.007) and severe-intensity cycling (-49 ± 13% vs. -40 ± 7%; P = 0.048). Except for heavy intensity, voluntary activation reductions were similar between modes. Similarly, except for dyspnea, which was lower for SL versus DL across all domains, ratings of fatigue, pain, and effort were similar at Tlim between exercise modes. Thus, the amount of muscle mass modulates the extent of contractile function impairment in an intensity-dependent manner.NEW & NOTEWORTHY We investigated the modulatory role of muscle mass on performance and perceived fatigability across the entire intensity spectrum. Despite similar time-to-task failure, single-leg cycling resulted in greater impairments in muscle contractile function within the heavy- and severe-intensity domains, but not the moderate- and extreme-intensity domains. Perceived fatigue, pain, and effort were similar between cycling modes. This indicates that the modulatory role of muscle mass on the extent of performance fatigability is intensity domain-dependent.

Effects of acute simulated altitude on the maximal lactate steady state in humans.

We sought to determine the effects of acute simulated altitude on the maximal lactate steady state (MLSS) and physiological responses to cycling at and 10 W above the MLSS-associated power output (PO) (MLSSp and MLSSp+10, respectively). Eleven (4 females) participants (means [SD]; 28 [4] yr; V̇o2max: 54.3 [6.9] mL·kg-1·min-1) acclimatized to ∼1,100 m performed 30-min constant PO trials in simulated altitudes of 0 m sea level (SL), 1,111 m mild altitude (MILD), and 2,222 m moderate altitude (MOD). MLSSp, defined as the highest PO with stable (<1 mM change) blood lactate concentration ([BLa]) between 10 and 30 min, was significantly lower in MOD (209 [54] W) compared with SL (230 [56] W; P < 0.001) and MILD (225 [58] W; P = 0.001), but MILD and SL were not different (P = 0.12). V̇o2 and V̇co2 decreased at higher simulated altitudes due to lower POs (P < 0.05), but other end-exercise physiological responses (e.g., [BLa], ventilation [V̇e], heart rate [HR]) were not different between conditions at MLSSp or MLSSp + 10 (P > 0.05). At the same absolute intensity (MLSSp for MILD), [BLa], HR, and V̇E and all perceptual variables were exacerbated in MOD compared with SL and MILD (P < 0.05). Maximum voluntary contraction, voluntary activation, and potentiated twitch forces were exacerbated at MLSSp + 10 relative to MLSSp within conditions (P < 0.05); however, condition did not affect performance fatiguability at the same relative or absolute intensity (P > 0.05). As MLSSp decreased in hypoxia, adjustments in PO are needed to ensure the same relative intensity across altitudes, but common indices of exercise intensity may facilitate exercise prescription and monitoring in hypoxia.NEW & NOTEWORTHY This study demonstrates the power output and metabolic rate associated with the maximal lactate steady-state (MLSS) decline in response to simulated altitude; however, common indices of exercise intensity remained unchanged when cycling was performed at the work rate associated with MLSS at each simulated altitude. These results support previous studies that investigated the effects of hypoxia on alternative measures of the critical intensity of exercise and will inform exercise prescription/monitoring across altitudes.

Risk Factors and Inequities in Transportation Injury and Mortality in the Canadian Census Health and Environment Cohorts (CanCHECs).

BACKGROUND: Road traffic injury contributes substantially to morbidity and mortality. Canada stands out among developed countries in not conducting a national household travel survey, leading to a dearth of national transportation mode data and risk calculations that have appropriate denominators. Since traffic injuries are specific to the mode of travel used, these risk calculations should consider travel mode. METHODS: Census data on mode of commute is one of the few sources of these data for persons aged 15 and over. This study leveraged a national data linkage cohort, the Canadian Census Health and Environment Cohorts, that connects census sociodemographic and commute mode data with records of deaths and hospitalizations, enabling assessment of road traffic injury associations by indicators of mode of travel (commuter mode). We examined longitudinal (1996-2019) bicyclist, pedestrian, and motor vehicle occupant injury and fatality risk in the Canadian Census Health and Environment Cohorts by commuter mode and sociodemographic characteristics using Cox proportional hazards models within the working adult population. RESULTS: We estimated positive associations between commute mode and same mode injury and fatality, particularly for bicycle commuters (hazard ratios for bicycling injury was 9.1 and for bicycling fatality was 11). Low-income populations and Indigenous people had increased injury risk across all modes. CONCLUSIONS: This study shows inequities in transportation injury risk in Canada and underscores the importance of adjusting for mode of travel when examining differences between population groups.

Physiological assessment of a 16 day, 4385 km ultra-endurance mountain bike race: A case study.

The Tour Divide (TD) is a 4385 km ultra-endurance bicycle race that follows the continental divide from Canada to Mexico. In this case study, we performed a comprehensive molecular and physiological profile before and after the completion of the TD. Assessments were performed 35 days before the start (Pre-TD) and ∼36 h after the finish (Post-TD). Total energy expenditure was assessed during the first 9 days by doubly labelled water (2 H2 18 O), abdominal and leg tissue volumes via MRI, and graded exercise tests to quantify fitness and substrate preference. Vastus lateralis muscle biopsies were taken to measure mitochondrial function via respirometry, and vascular function was assessed using Doppler ultrasound. The 47-year-old male subject took 16 days 7 h 45 min to complete the route. He rode an average of 16.8 h/day. Neither maximal O2 uptake nor maximal power output changed pre- to post-TD. Measurement of total energy expenditure and dietary recall records suggested maintenance of energy balance, which was supported by the lack of change in body weight. The subject lost both appendicular and trunk fat mass and gained leg lean mass pre- to post-TD. Skeletal muscle mitochondrial and vascular endothelial function decreased pre- to post-TD. Overall, exercise performance was maintained despite reductions in muscle mitochondrial and vascular endothelial function post-TD, suggesting a metabolic reserve in our highly trained athlete.

Composite activity type and stride-specific energy expenditure estimation model for thigh-worn accelerometry.

BACKGROUND: Accurately measuring energy expenditure during physical activity outside of the laboratory is challenging, especially on a large scale. Thigh-worn accelerometers have gained popularity due to the possibility to accurately detect physical activity types. The use of machine learning techniques for activity classification and energy expenditure prediction may improve accuracy over current methods. Here, we developed a novel composite energy expenditure estimation model by combining an activity classification model with a stride specific energy expenditure model for walking, running, and cycling. METHODS: We first trained a supervised deep learning activity classification model using pooled data from available adult accelerometer datasets. The composite energy expenditure model was then developed and validated using additional data based on a sample of 69 healthy adult participants (49% female; age = 25.2 ± 5.8 years) who completed a standardised activity protocol with indirect calorimetry as the reference measure. RESULTS: The activity classification model showed an overall accuracy of 99.7% across all five activity types during validation. The composite model for estimating energy expenditure achieved a mean absolute percentage error of 10.9%. For running, walking, and cycling, the composite model achieved a mean absolute percentage error of 6.6%, 7.9% and 16.1%, respectively. CONCLUSIONS: The integration of thigh-worn accelerometers with machine learning models provides a highly accurate method for classifying physical activity types and estimating energy expenditure. Our novel composite model approach improves the accuracy of energy expenditure measurements and supports better monitoring and assessment methods in non-laboratory settings.

A systematic review on the associations between the built environment and adult's physical activity in global tropical and subtropical climate regions.

BACKGROUND: Physical inactivity is a major public health concern, exacerbated in countries with a (sub)tropical climate. The built environment can facilitate physical activity; however, current evidence is mainly from North American and European countries with activity-friendly climate conditions. This study explored associations between built environment features and physical activity in global tropical or subtropical dry or desert climate regions. METHODS: A systematic review of four major databases (Web of Science, Scopus, PubMed, and SportDISCUS) was performed. To be included, studies had to investigate associations between perceived or objective built environment characteristics and adult's physical activity and had to be conducted in a location with (sub)tropical climate. Each investigated association was reported as one case and results were synthesized based upon perceived and objectively assessed environment characteristics as well as Western and non-Western countries. Study quality was evaluated using a tool designed for assessing studies on built environment and physical activity. RESULTS: Eighty-four articles from 50 studies in 13 countries with a total of 2546 built environment-physical activity associations were included. Design (connectivity, walking/cycling infrastructure), desirability (aesthetics, safety), and destination accessibility were the built environment characteristics most frequently associated with physical activity across the domains active transport, recreational physical activity, total walking and cycling, and moderate-to-vigorous physical activity, particularly if multiple attributes were present at the same time. Very few studies assessed built environment attributes specifically relevant to physical activity in (sub)tropical climates. Most studies were conducted in Western countries, with results being largely comparable with non-Western countries. Findings were largely generalizable across gender and age groups. Results from natural experiments indicated that relocating to an activity-friendly neighborhood impacted sub-groups differently. CONCLUSIONS: Built environment attributes, including destination accessibility, connectivity, walking and cycling infrastructure, safety, and aesthetics, are positively associated with physical activity in locations with (sub)tropical climate. However, few studies focus on built environment attributes specifically relevant in a hot climate, such as shade or indoor recreation options. Further, there is limited evidence from non-Western countries, where most of the urban population lives in (sub)tropical climates. Policy makers should focus on implementing activity-friendly environment attributes to create sustainable and climate-resilient cities.

Uncovering physical activity trade-offs in transportation policy: A spatial agent-based model of Bogotá, Colombia.

BACKGROUND: Transportation policies can impact health outcomes while simultaneously promoting social equity and environmental sustainability. We developed an agent-based model (ABM) to simulate the impacts of fare subsidies and congestion taxes on commuter decision-making and travel patterns. We report effects on mode share, travel time and transport-related physical activity (PA), including the variability of effects by socioeconomic strata (SES), and the trade-offs that may need to be considered in the implementation of these policies in a context with high levels of necessity-based physical activity. METHODS: The ABM design was informed by local stakeholder engagement. The demographic and spatial characteristics of the in-silico city, and its residents, were informed by local surveys and empirical studies. We used ridership and travel time data from the 2019 Bogotá Household Travel Survey to calibrate and validate the model by SES. We then explored the impacts of fare subsidy and congestion tax policy scenarios. RESULTS: Our model reproduced commuting patterns observed in Bogotá, including substantial necessity-based walking for transportation. At the city-level, congestion taxes fractionally reduced car use, including among mid-to-high SES groups but not among low SES commuters. Neither travel times nor physical activity levels were impacted at the city level or by SES. Comparatively, fare subsidies promoted city-level public transportation (PT) ridership, particularly under a 'free-fare' scenario, largely through reductions in walking trips. 'Free fare' policies also led to a large reduction in very long walking times and an overall reduction in the commuting-based attainment of physical activity guidelines. Differential effects were observed by SES, with free fares promoting PT ridership primarily among low-and-middle SES groups. These shifts to PT reduced median walking times among all SES groups, particularly low-SES groups. Moreover, the proportion of low-to-mid SES commuters meeting weekly physical activity recommendations decreased under the 'freefare' policy, with no change observed among high-SES groups. CONCLUSIONS: Transport policies can differentially impact SES-level disparities in necessity-based walking and travel times. Understanding these impacts is critical in shaping transportation policies that balance the dual aims of reducing SES-level disparities in travel time (and time poverty) and the promotion of choice-based physical activity.

Thigh-worn accelerometry: a comparative study of two no-code classification methods for identifying physical activity types.

BACKGROUND: The more accurate we can assess human physical behaviour in free-living conditions the better we can understand its relationship with health and wellbeing. Thigh-worn accelerometry can be used to identify basic activity types as well as different postures with high accuracy. User-friendly software without the need for specialized programming may support the adoption of this method. This study aims to evaluate the classification accuracy of two novel no-code classification methods, namely SENS motion and ActiPASS. METHODS: A sample of 38 healthy adults (30.8 ± 9.6 years; 53% female) wore the SENS motion accelerometer (12.5 Hz; ±4 g) on their thigh during various physical activities. Participants completed standardized activities with varying intensities in the laboratory. Activities included walking, running, cycling, sitting, standing, and lying down. Subsequently, participants performed unrestricted free-living activities outside of the laboratory while being video-recorded with a chest-mounted camera. Videos were annotated using a predefined labelling scheme and annotations served as a reference for the free-living condition. Classification output from the SENS motion software and ActiPASS software was compared to reference labels. RESULTS: A total of 63.6 h of activity data were analysed. We observed a high level of agreement between the two classification algorithms and their respective references in both conditions. In the free-living condition, Cohen's kappa coefficients were 0.86 for SENS and 0.92 for ActiPASS. The mean balanced accuracy ranged from 0.81 (cycling) to 0.99 (running) for SENS and from 0.92 (walking) to 0.99 (sedentary) for ActiPASS across all activity types. CONCLUSIONS: The study shows that two available no-code classification methods can be used to accurately identify basic physical activity types and postures. Our results highlight the accuracy of both methods based on relatively low sampling frequency data. The classification methods showed differences in performance, with lower sensitivity observed in free-living cycling (SENS) and slow treadmill walking (ActiPASS). Both methods use different sets of activity classes with varying definitions, which may explain the observed differences. Our results support the use of the SENS motion system and both no-code classification methods.

Understanding how and why travel mode changes: analysis of longitudinal qualitative interviews.

BACKGROUND: Encouraging alternatives to the car such as walking, cycling or public transport is a key cross-sector policy priority to promote population and planetary health. Individual travel choices are shaped by individual and environmental contexts, and changes in these contexts - triggered by key events - can translate to changes in travel mode. Understanding how and why these changes happen can help uncover more generalisable findings to inform future intervention research. This study aimed to identify the mechanisms and contexts facilitating changes in travel mode. METHODS: Prospective longitudinal qualitative cohort study utilising semi-structured interviews at baseline (in 2021), three- and six-month follow up. Participants were residents in a new town in Cambridgeshire, UK, where design principles to promote walking, cycling and public transport were used at the planning stage. At each interview, we followed a topic guide asking participants about previous and current travel patterns and future intentions. All interviews were audio recorded and transcribed. Data analysis used the framework approach based on realist evaluation principles identifying the context and mechanisms described by participants as leading to travel behaviour change. RESULTS: We conducted 42 interviews with 16 participants and identified six mechanisms for changes in travel mode. These entailed increasing or reducing access, reliability and financial cost, improving convenience, increasing confidence and raising awareness. Participants described that these led to changes in travel mode in contexts where their existing travel mode had been disrupted, particularly in terms of reducing access or reliability or increasing cost, and where there were suitable alternative travel modes for their journey. Experiences of the new travel mode played a role in future travel intentions. IMPLICATIONS: Applying realist evaluation principles to identify common mechanisms for changes in travel mode has the potential to inform future intervention strategies. Future interventions using mechanisms that reduce access to, reduce reliability of, or increase the financial cost of car use may facilitate modal shift to walking, cycling and public transport when implemented in contexts where alternative travel modes are available and acceptable.

Reliability of transcranial magnetic stimulation-evoked responses on knee extensor muscles during cycling.

Transcranial magnetic stimulation (TMS) measures the excitability and inhibition of corticomotor networks. Despite its task-specificity, few studies have used TMS during dynamic movements and the reliability of TMS paired pulses has not been assessed during cycling. This study aimed to evaluate the reliability of motor evoked potentials (MEP) and short- and long-interval intracortical inhibition (SICI and LICI) on vastus lateralis and rectus femoris muscle activity during a fatiguing single-leg cycling task. Nine healthy adults (2 female) performed two identical sessions of counterweighted single-leg cycling at 60% peak power output until failure. Five single pulses and ten paired pulses were delivered to the motor cortex, and two maximal femoral nerve stimulations (Mmax) were administered during two baseline cycling bouts (unfatigued) and every 5 min throughout cycling (fatigued). When comparing both baseline bouts within the same session, MEP·Mmax-1 and LICI (both ICC: >0.9) were rated excellent while SICI was rated good (ICC: 0.7-0.9). At baseline, between sessions, in the vastus lateralis, Mmax (ICC: >0.9) and MEP·Mmax-1 (ICC: 0.7) demonstrated good reliability; LICI was moderate (ICC: 0.5), and SICI was poor (ICC: 0.3). Across the fatiguing task, Mmax demonstrated excellent reliability (ICC > 0.8), MEP·Mmax-1 ranged good to excellent (ICC: 0.7-0.9), LICI was moderate to excellent (ICC: 0.5-0.9), and SICI remained poorly reliable (ICC: 0.3-0.6). These results corroborate the cruciality of retaining mode-specific testing measurements and suggest that during cycling, Mmax, MEP·Mmax-1, and LICI measures are reliable whereas SICI, although less reliable across days, can be reliable within the same session.

Effects of workload and saddle height on muscle activation of the lower limb during cycling.

BACKGROUND: Cycling workload is an essential factor in practical cycling training. Saddle height is the most studied topic in bike fitting, but the results are controversial. This study aims to investigate the effects of workload and saddle height on the activation level and coordination of the lower limb muscles during cycling. METHODS: Eighteen healthy male participants with recreational cycling experience performed 15 × 2-min constant cadence cycling at five saddle heights of 95%, 97%, 100%, 103%, and 105% of greater trochanter height (GTH) and three cycling workloads of 25%, 50%, and 75% of functional threshold power (FTP). The EMG signals of the rectus femoris (RF), tibialis anterior (TA), biceps femoris (BF), and medial gastrocnemius (MG) of the right lower limb were collected throughout the experiment. RESULTS: Greater muscle activation was observed for the RF and BF at a higher cycling workload, whereas no differences were observed for the TA and MG. The MG showed intensified muscle activation as the saddle height increased. The mean and maximum amplitudes of the EMG signals of the MG increased by 56.24% and 57.24% at the 25% FTP workload, 102.71% and 126.95% at the 50% FTP workload, and 84.27% and 53.81% at the 75% FTP workload, respectively, when the saddle height increased from 95 to 100% of the GTH. The muscle activation level of the RF was minimal at 100% GTH saddle height. The onset and offset timing revealed few significant differences across cycling conditions. CONCLUSIONS: Muscle activation of the RF and BF was affected by cycling workload, while that of the MG was affected by saddle height. The 100% GTH is probably the appropriate saddle height for most cyclists. There was little statistical difference in muscle activation duration, which might be related to the small workload.

Longitudinal and Concurrent Effortful Control as Predictors of Risky Bicycling in Adolescence: Moderating Effects of Age and Gender.

OBJECTIVE: Collisions between bicycles and motor vehicles are one of the leading risk factors for injury and death in childhood and adolescence. We examined longitudinal and concurrent effortful control (EC) as predictors of risky bicycling behavior in early- to mid-adolescence, with age and gender as moderators. We also examined whether EC was associated with parent-reported real-world bicycling behavior and all lifetime unintentional injuries. METHODS: Parent-reported EC measures were collected when children (N = 85) were 4 years old and when they were either 10 years (N = 42) or 15 years (N = 43) old. We assessed risky bicycling behavior by asking the adolescents to bicycle across roads with high-density traffic in an immersive virtual environment. Parents also reported on children's real-world bicycling behavior and lifetime unintentional injuries at the time of the bicycling session. RESULTS: We found that both longitudinal and concurrent EC predicted adolescents' gap choices, though these effects were moderated by age and gender. Lower parent-reported early EC in younger and older girls predicted a greater willingness to take tight gaps (3.5 s). Lower parent-reported concurrent EC in older boys predicted a greater willingness to take gaps of any size. Children lower in early EC started bicycling earlier and were rated as less cautious bicyclists as adolescents. Adolescents lower in concurrent EC were also rated as less cautious bicyclists and had experienced more lifetime unintentional injuries requiring medical attention. CONCLUSION: Early measures of child temperament may help to identify at-risk populations who may benefit from parent-based interventions.

Bicycling for Rehabilitation of Persons With Parkinson Disease: A Scoping Review.

BACKGROUND AND PURPOSE: Exercise is beneficial for persons with Parkinson disease (PwPD). The overarching purpose of this scoping review was to provide guidance to clinicians and scientists regarding current evidence for bicycling exercise for PwPD. A scoping review was conducted to examine the heterogeneous literature on stationary bicycling for PwPD to reduce motor symptoms and body function structure impairments, improve activities and motor performance, and reduce disease severity. METHODS: The Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines were followed. PubMed, CINAHL, and PEDro were searched from inception to January 23, 2023. Articles reporting original data on relevant outcome measures were included. Search results were screened and articles were extracted. Data were analyzed quantitatively with percentages of significant and clinically meaningful findings and qualitatively to extract themes. RESULTS: Bicycling was categorized using bicycle types (assisted, nonassisted) and training modes (speed, aerobic, force). A high percentage of the 34 studies showed statistical significance for reducing motor symptoms (83%), body function structure impairments (78%), disease severity (82%), and improving activities (gait 72%, balance 60%). Clinically meaningful findings were achieved in 71% of the studies for reduction in disease severity and in 50% for improving gait. DISCUSSION AND CONCLUSIONS: The literature on bicycling for PwPD has evolved from speed to aerobic studies. The terminology describing types of bicycling was simplified. Of all the outcomes reported, reduction of disease severity achieved the highest frequency of clinical meaningful improvements. Bicycling was comparable with other forms of aerobic training for walking speed and endurance. Opportunities for translation to practice and research are presented.

The use of Virtual Reality (VR) to assess the impact of geographical environments on walking and cycling: a systematic literature review.

BACKGROUND: Geographical environments influence people's active mobility behaviors, contributing to their physical and mental health. The use of Virtual Reality (VR) in experimental research can unveil new insights into the relationship between exposure to geographic environments and active mobility behaviors. This systematic review aims to (1) identify environmental attributes investigated in relation with walking and cycling, using VR, (2) assess their impacts on active mobility behaviors and attitudes, and (3) identify research gaps, strengths and limitations in VR-based experimental research. METHODS: Articles published between January 2010 and February 2022 within five databases (PubMed, Scopus, EBSCO, IEEE Xplore, and Cochrane Library) were explored using three keywords and their synonyms: Virtual Reality, Active mobility behavior, and Geographical environments. Studies focusing on indoor environments, driving simulation, disease-specific groups, non-relevant disciplines (e.g. military, emergency evacuation), VR methodology/software optimization, and those with static participants' involvement were excluded. The full protocol is available from PROSPERO (ID = CRD42022308366). RESULTS: Out of 3255 articles, 18 peer-reviewed papers met the selection criteria, mostly focusing on walking (83%). Most studies used head-mounted displays (94%) and relied on convenience sampling (72% below 100 participants). Both static (33%) and dynamic (45%) environmental attributes have been investigated, with only 22% of them simultaneously in the same virtual environment. Greenness and crowd density were the most frequent attributes, rather consistently associated with emotional states and movement behaviors. Few studies have taken into account participant's previous VR experience (33%) and cybersickness (39%) while both are likely to affect an individual's perception and behavior. CONCLUSIONS: Future research should explore a broader range of environmental attributes, including static and dynamic ones, as well as a more complex integration of these attributes within a single experiment to mimic the effect of realistic environments on people's active mobility behaviors and attitudes. Larger and more diverse population samples are deemed required to improve result generalizability. Despite methodological challenges, VR emerges as a promising tool to disentangle the effect of complex environments on active mobility behaviors.

Effect of Adding Early Bedside Cycling to Inpatient Cardiac Rehabilitation on Physical Function and Length of Stay After Heart Valve Surgery: A Randomized Controlled Trial.

OBJECTIVE: To assess whether adding bedside cycling to inpatient cardiac rehabilitation (CR) early after heart valve surgery could lead to better physical function and shorter length of hospital stays. DESIGN: This is a single-centered, randomized, controlled, parallel-group intervention study. SETTINGS: This study was conducted at the National Heart Institute from December 2022 to June 2023. PARTICIPANTS: Thirty-one patients following heart valve surgery completed this study after being randomized into 2 groups: an intervention group (n1=16) and an active control group (n2=15). Eligibility criteria were heart valve surgery with median sternotomy, clinical stability, and age from 20 to 40 years. INTERVENTIONS: The intervention group received early bedside cycling for the lower limbs, using a mini bike, in addition to an inpatient CR program, and the control group received the inpatient CR program alone. MAIN OUTCOME MEASURE: The primary outcome was the physical functional capacity assessed by the 6-minute walk distance (6MWD). The secondary outcomes were the Barthel Index (BI), the forced vital capacity (FVC), the length of intensive care unit (ICU) stay, the total length of hospital stay, and the physical component summary (PCS) of the 12-item Short Form (SF-12) Health Survey. RESULTS: Compared with the control group, the intervention group showed significantly greater 6MWD (P<.001), BI score (P<.001), and FVC (P=.006) at hospital discharge, and shorter ICU stay (P=.002) and total hospital stay (P=.015). At 1-month follow-up, the intervention group showed a non-significantly higher PCS mean score than the control group (P=.057). CONCLUSION: Adding early bedside cycling to a usual inpatient CR program after heart valve surgery could induce significantly greater short-term physical functional capacity as assessed by the 6MWD, better activities of daily living as evaluated by the BI, higher pulmonary function as measured by the FVC, and shorter lengths of ICU and total hospital stays than the usual inpatient CR program alone.

An 8-week Forced-rate Aerobic Cycling Program Improves Cardiorespiratory Fitness in Persons With Chronic Stroke: A Randomized Controlled Trial.

OBJECTIVE: To examine the cardiorespiratory effects of a forced-rate aerobic exercise (FE) intervention among individuals with chronic stroke compared with an upper extremity repetitive task practice (UE RTP) control group. DESIGN: Secondary analysis of data from a randomized controlled trial. SETTING: Research laboratory. PARTICIPANTS: Individuals with chronic stroke (N=60). INTERVENTIONS: Participants completed 24 sessions of FE followed by RTP (FE+RTP, N=30) or time matched RTP alone (N=30). The FE+RTP group was prescribed exercise at 60%-80% of heart rate reserve on a motorized stationary cycle ergometer for 45 minutes followed by 45 minutes of RTP. The control group completed 90 minutes of RTP. MAIN OUTCOME MEASURES: Metabolic exercise stress tests on a cycle ergometer were conducted at baseline and post-intervention. Outcomes included peak oxygen consumption (peak V̇o2) and anaerobic threshold (AT). RESULTS: Fifty participants completed the study intervention and pre/post stress tests. The FE+RTP group demonstrated significantly greater improvements in peak V̇o2 from 16.4±5.7 to 18.3±6.4 mL/min/kg compared with the RTP group (17.0±5.6 to 17.2±5.6 mL/min/kg, P=.020) and significantly greater improvements in AT from 10.3±2.8 to 11.5±3.6 mL/min/kg compared with the RTP group (10.8±3.9 to 10.4±3.2 mL/min/kg, P=.020). In analyzing predictors of post-intervention peak V̇o2, the multivariable linear regression model did not reveal a significant effect of age, sex, body mass index, or beta blocker usage. Similarly, bivariate linear regression models for the FE group only did not find any exercise variables (aerobic intensity, power, or cycling cadence) to be significant predictors of peak V̇o2. CONCLUSIONS: While the aerobic exercise intervention was integrated into rehabilitation to improve UE motor recovery, it was also effective in eliciting significant and meaningful improvements in cardiorespiratory fitness. This novel rehabilitation model may be an effective approach to improve motor and cardiorespiratory function in persons recovering from stroke.