Bas de Geus

Guidelines to Classify Subject Groups in Sport-Science Research

AIM To review current cycling-related sport-science literature to formulate guidelines to classify female subject groups and to compare this classification system for female subject groups with the classification system for male subject groups. METHODS A database of 82 papers that described female subject groups containing information on preexperimental maximal cycle-protocol designs, terminology, biometrical and physiological parameters, and cycling experience was analyzed. Subject groups were divided into performance levels (PLs), according to the nomenclature. Body mass, body-mass index, maximal oxygen consumption (VO2max), peak power output (PPO), and training status were compared between PLs and between female and male PLs. RESULTS Five female PLs were defined, representing untrained, active, trained, well-trained, and professional female subjects. VO2max and PPO significantly increased with PL, except for PL3 and PL4 (P < .01). For each PL, significant differences were observed in absolute and relative VO2max and PPO between male and female subject groups. Relative VO2max is the most cited parameter for female subject groups and is proposed as the principal parameter to classify the groups. CONCLUSION This systematic review shows the large variety in the description of female subject groups in the existing literature. The authors propose a standardized preexperimental testing protocol and guidelines to classify female subject groups into 5 PLs based on relative VO2max, relative PPO, training status, absolute VO2max, and absolute PPO.

Subclinical responses in healthy cyclists briefly exposed to traffic-related air pollution: an intervention study

BackgroundNumerous epidemiological studies have demonstrated adverse health effects of a sedentary life style, on the one hand, and of acute and chronic exposure to traffic-related air pollution, on the other. Because physical exercise augments the amount of inhaled pollutants, it is not clear whether cycling to work in a polluted urban environment should be encouraged or not. To address this conundrum we investigated if a bicycle journey along a busy commuting road would induce changes in biomarkers of pulmonary and systematic inflammation in a group of healthy subjects.Methods38 volunteers (mean age: 43 ± 8.6 years, 26% women) cycled for about 20 minutes in real traffic near a major bypass road (road test; mean UFP exposure: 28,867 particles per cm3) in Antwerp and in a laboratory with filtered air (clean room; mean UFP exposure: 496 particles per cm3). The exercise intensity (heart rate) and duration of cycling were similar for each volunteer in both experiments. Exhaled nitric oxide (NO), plasma interleukin-6 (IL-6), platelet function, Clara cell protein in serum and blood cell counts were measured before and 30 minutes after exercise.ResultsPercentage of blood neutrophils increased significantly more (p = 0.004) after exercise in the road test (3.9%; 95% CI: 1.5 to 6.2%; p = 0.003) than after exercise in the clean room (0.2%; 95% CI: -1.8 to 2.2%, p = 0.83). The pre/post-cycling changes in exhaled NO, plasma IL-6, platelet function, serum levels of Clara cell protein and number of total blood leukocytes did not differ significantly between the two scenarios.ConclusionsTraffic-related exposure to particles during exercise caused a small increase in the distribution of inflammatory blood cells in healthy subjects. The health significance of this isolated change is unclear.

Influence of climbing style on physiological responses during indoor rock climbing on routes with the same difficulty

The objectives of this study were to (1) continuously assess oxygen uptake and heart rate; (2) quantify the extent to which maximal whole-body cardiorespiratory capacity is utilized during climbing on four routes with the same difficulty but different steepness and/or displacement. Fifteen expert climbers underwent a maximal graded exercise test (MT), on a treadmill, in order to assess their maximal physiological capacity. After MT, four sport routes, equal in difficulty rating but different in steepness and/or displacement, were climbed. Oxygen uptake and heart rate were continuously measured. Respiratory exchange ratio (RER) was calculated. Blood lactate concentration and rating of perceived exertion (RPE) were taken before and directly after climbing. Data were expressed as peak values (HRpeak, VO2peak and RERpeak) and as averages over the entire climb (HRavg, VO2avg and RERavg). During climbing, higher HRpeak and HRavg were found in routes with a vertical upward displacement in comparison to traversing routes with a horizontal displacement. The average absolute and relative oxygen uptake was significantly lower in the traversing route in comparison with the three other routes. The traverse is done at a lower percent of the running maximum. Comparing four routes with the same difficulty but different steepness and/or displacement shows that (1) routes with an upward displacement causes the highest peak and average heart rate; (2) routes with a vertical displacement on overhanging wall is physiologically the most demanding; (3) the traverse is physiologically the less demanding.

An international review of the frequency of single-bicycle crashes (SBCs) and their relation to bicycle modal share

Objectives To study cyclists’ share of transport modes (modal share) and single-bicycle crashes (SBCs) in different countries in order to investigate if the proportion of cyclist injuries resulting from SBCs is affected by variation in modal share. Methods A literature search identified figures (largely from western countries) on SBC casualties who are fatally injured, hospitalised or treated at an emergency department. Correlation and regression analyses were used to investigate how bicycle modal share is related to SBCs. Results On average, 17% of fatal injuries to cyclists are caused by SBCs. Different countries show a range of values between 5% and 30%. Between 60% and 95% of cyclists admitted to hospitals or treated at emergency departments are victims of SBCs. The proportion of all injured cyclists who are injured in SBCs is unrelated to the share of cycling in the modal split. The share of SBC casualties among the total number of road crash casualties increases proportionally less than the increase in bicycle modal share. Conclusions While most fatal injuries among cyclists are due to motor vehicle–bicycle crashes, most hospital admissions and emergency department attendances result from SBCs. As found in previous studies of cyclists injured in collisions, this study found that the increase in the number of SBC casualties is proportionally less than the increase in bicycle modal share.

Exposure measurement in bicycle safety analysis: A review of the literature.

BACKGROUND Cycling, as an active mode of transportation, has well-established health benefits. However, the safety of cyclists in traffic remains a major concern. In-depth studies of potential risk factors and safety outcomes are needed to ensure the most appropriate actions are taken to improve safety. However, the lack of reliable exposure data hinders meaningful analysis and interpretation. In this paper, we review the bicycle safety literature reporting different methods for measuring cycling exposure and discuss their findings. METHODS A literature search identified studies on bicycle safety that included a description of how cycling exposure was measured, and what exposure units were used (e.g. distance, time, trips). Results were analyzed based on whether retrospective or prospective measurement of exposure was used, and whether safety outcomes controlled for exposure. RESULTS We analyzed 20 papers. Retrospective studies were dominated by major bicycle accidents, whereas the prospective studies included minor and major bicycle accidents. Retrospective studies indicated higher incidence rates (IR) of accidents for men compared to women, and an increased risk of injury for cyclists aged 50 years or older. There was a lack of data for cyclists younger than 18 years. The risk of cycling accidents increased when riding in the dark. Wearing visible clothing or a helmet, or having more cycling experience did not reduce the risk of being involved in an accident. Better cyclist-driver awareness and more interaction between car driver and cyclists, and well maintained bicycle-specific infrastructure should improve bicycle safety. CONCLUSION The need to include exposure in bicycle safety research is increasingly recognized, but good exposure data are often lacking, which makes results hard to interpret and compare. Studies including exposure often use a retrospective research design, without including data on minor bicycle accidents, making it difficult to compare safety levels between age categories or against different types of infrastructure. Future research should focus more on children and adolescents, as this age group is a vulnerable population and is underrepresented in the existing literature.

Psychosocial and Environmental Correlates of Walking, Cycling, Public Transport and Passive Transport to Various Destinations in Flemish Older Adolescents.

Background Active transport is a convenient way to incorporate physical activity in adolescents’ daily life. The present study aimed to investigate which psychosocial and environmental factors are associated with walking, cycling, public transport (train, tram, bus, metro) and passive transport (car, motorcycle, moped) over short distances (maximum eight kilometres) among older adolescents (17–18 years), to school and to other destinations. Methods 562 older adolescents completed an online questionnaire assessing socio-demographic variables, psychosocial variables, environmental variables and transport to school/other destinations. Zero-inflated negative binomial regression models were performed. Results More social modelling and a higher residential density were positively associated with walking to school and walking to other destinations, respectively. Regarding cycling, higher self-efficacy and a higher social norm were positively associated with cycling to school and to other destinations. Regarding public transport, a higher social norm, more social modelling of siblings and/or friends, more social support and a higher land use mix access were positively related to public transport to school and to other destinations, whereas a greater distance to school only related positively to public transport to school. Regarding passive transport, more social support and more perceived benefits were positively associated with passive transport to school and to other destinations. Perceiving less walking and cycling facilities at school was positively related to passive transport to school only, and more social modelling was positively related to passive transport to other destinations. Conclusions Overall, psychosocial variables seemed to be more important than environmental variables across the four transport modes. Social norm, social modelling and social support were the most consistent psychosocial factors which indicates that it is important to target both older adolescents and their social environment in interventions promoting active transport. Walking or cycling together with siblings or friends has the potential to increase social norm, social modelling and social support towards active transport.

Influence of electrically assisted cycling on physiological parameters in untrained subjects

Abstract Electrically assisted bicycles (EAB) as a form of transport not only offer the potential to reduce energy use and environmental impact but could also be an effective way of encouraging active living. The purpose of this study is to assess the influence of physical active commuting to work using an EAB, on physiological parameters in 20 untrained men and women. Tests were performed at three different time points over a 10-week period, including four weeks of passive (control period) and six weeks of active commuting (intervention period). ANOVA for repeated measures was used to test differences between the testing series for the most important physiological parameters: Pmax·kg−1, V˙O2peak·kg−1, fixed blood lactate concentration (2, 4 mmol·l−1). The subjects performed over a 6-week period a mean total cycling distance of 405.1±156.0 km with a weekly frequency of 4.1±1.7 days·week−1 for men and 246.0±116.3 km with a frequency of 2.9±1.0 days·week−1 for women. Pmax·kg−1 significantly increased in men and women after 6 weeks of active commuting. Power output at 2 mmol·l−1 significantly increased in women (P=0.001) but not in men (P=0.0604). Power output at 4 mmol·l−1 significantly increased for men and women. V˙O2peak·kg−1 did not differ. With respect to the study limitations, it is concluded that cycling to work on an EAB was effective in increasing the maximal power output and power output at 4 mmol·l−1 in these untrained subjects. Cycling on an EAB seems to be a promising tool as a health enhancing physical activity, for those who will benefit the most in terms of health related fitness, namely the physically inactive, unfit and older people.

Effect of Five Different Recovery Methods on Repeated Cycle Performance

PURPOSE The aim of this study was to determine the influence of five different recovery strategies on repeated simulated time trial (TT) performance on a stationary cycle ergometer. METHODS Study 1 (n=8, male, club-level trained; V˙O2max: 56.9 ± 3.8 mL·min·kg) investigated the influence of passive rest with or without upper leg cooling (cooling device set at 0 °C or 10 °C) and compression after a first time trial (TT1) on a second time trial (TT2). Study 2 (n=9, male, club-level trained; V˙O2max: 53.3 ± 5.2 mL·min·kg) examined the influence of active recovery (AR) with or without upper leg cooling (cooling device set at 0 °C) applied after TT1 on TT2. Exhaustive exercise consisted of a cycle exercise at 55% Wmax lasting 30 min, immediately followed by a TT in which subjects had to complete a preset amount of work, equal to 30 min at 75% Wmax, as fast as possible. Immediately after TT1, a different recovery intervention was used for 20 min, and then subjects passively rested for 100 min before starting TT2. TT performance and physiological parameters were registered during the experiments. RESULTS In both studies, we observed that TT performance did not significantly change for either of the recovery interventions. During the cooling interventions, skin temperatures significantly decreased (P<0.05). AR + cooling + compression versus AR (study 2) clearly showed a significantly (P<0.05) faster decrease of the blood lactate concentration ([BLa]) during the recovery period after TT1 and a lower [BLa] during TT2. CONCLUSIONS Twenty minutes after cooling (device set at 0 °C or 10 °C), AR or the combined recovery method had comparable effects as passive recovery on the maintenance of TT2 performance 120 min after the first TT (TT1). After AR, however, subjects seemed to perform slightly better during TT2.

Creating cycling-friendly environments for children: which micro-scale factors are most important? An experimental study using manipulated photographs

Background Increasing participation in transportation cycling represents a useful strategy for increasing children’s physical activity levels. Knowledge on how to design environments to encourage adoption and maintenance of transportation cycling is limited and relies mainly on observational studies. The current study experimentally investigates the relative importance of micro-scale environmental factors for children’s transportation cycling, as these micro-scale factors are easier to change within an existing neighborhood compared to macro-scale environmental factors (i.e. connectivity, land-use mix, …). Methods Researchers recruited children and their parents (n = 1232) via 45 randomly selected schools across Flanders and completed an online questionnaire which consisted of 1) demographic questions; and 2) a choice-based conjoint (CBC) task. During this task, participants chose between two photographs which we had experimentally manipulated in seven micro-scale environmental factors: type of cycle path; evenness of cycle path; traffic speed; traffic density; presence of speed bumps; environmental maintenance; and vegetation. Participants indicated which route they preferred to (let their child) cycle along. To find the relative importance of these micro-scale environmental factors, we conducted Hierarchical Bayes analyses. Results Type of cycle path emerged as the most important factor by far among both children and their parents, followed by traffic density and maintenance, and evenness of the cycle path among children. Among parents, speed limits and maintenance emerged as second most important, followed by evenness of the cycle path, and traffic density. Conclusion Findings indicate that improvements in micro-scale environmental factors might be effective for increasing children’s transportation cycling, since they increase the perceived supportiveness of the physical environment for transportation cycling. Investments in creating a clearly designated space for the young cyclist, separated from motorized traffic, appears to be the most effective way to increase perceived supportiveness. Future research should confirm our laboratory findings with experimental on-site research.

Cycling on a Bike Desk Positively Influences Cognitive Performance

Purpose Cycling desks as a means to reduce sedentary time in the office has gained interest as excessive sitting has been associated with several health risks. However, the question rises if people will still be as efficient in performing their desk-based office work when combining this with stationary cycling. Therefore, the effect of cycling at 30% Wmax on typing, cognitive performance and brain activity was investigated. Methods After two familiarisation sessions, 23 participants performed a test battery [typing test, Rey auditory verbal learning test (RAVLT), Stroop test and Rosvold continuous performance test (RCPT)] with electroencephalography recording while cycling and sitting on a conventional chair. Results Typing performance, performance on the RAVLT and accuracy on the Stroop test and the RCPT did not differ between conditions. Reaction times on the Stroop test and the RCPT were shorter while cycling relative to sitting (p < 0.05). N200, P300, N450 and conflict SP latency and amplitude on the Stroop test and N200 and P300 on the RCPT did not differ between conditions. Conclusions This study showed that typing performance and short-term memory are not deteriorated when people cycle at 30% Wmax. Furthermore, cycling had a positive effect on response speed across tasks requiring variable amounts of attention and inhibition.