Gymnastik- och idrottshögskolan, GIH

Purpose: Studies indicate that the rated perceived exertion (RPE) during physical exercise can be lower in field environments than indoors. The environmental conditions of those studies are explored. Furthermore, we study if the same phenomenon is valid when cycling indoors versus in cycle commuting environments with high levels of stimuli from both traffic and suburban-urban elements. 

Methods: Twenty commuter cyclists underwent measurements of heart rate (HR) and oxygen uptake (V̇O2) and RPE assessments for breathing and legs, respectively, while cycling in both laboratory and field conditions. A validated mobile metabolic system was used in the field to measure V̇O2. Three submaximal cycle ergometer workloads in the laboratory were used to establish linear regression equations between RPE and % of HR reserve (%HRR) and %V̇O2max, separately. Based on these equations, RPE from the laboratory was predicted and compared with RPE levels at the participants’ individual cycle commutes at equal intensities. The same approach was used to predict field intensities and for comparisons with corresponding measured intensities at equal RPE levels.    

Results: The predicted RPE levels based on the laboratory cycling were significantly higher than the RPE levels in cycle commuting at equal intensities (67% of HRR; 65% of V̇O2max). For breathing, the mean RPE levels were; 14.0-14.2 in the laboratory and 12.6 in the field. The corresponding levels for legs were; 14.0-14.2 and 11.5. The range of predicted field intensities in terms of %HRR and %V̇O2max was 46-56%, which corresponded to median differences of 19-30% compared to the measured intensities in field at equal RPE.  

Conclusion: The cycle commuters perceived a lower exertion during their cycle commutes compared to ergometer cycling in a laboratory at equal exercise intensities. This may be due to a higher degree of external stimuli in field, although influences from other possible causes cannot be ruled out.

Background 

It is important to examine how motorized traffic variables affect pedestrians along a gradient from rural to inner urban settings.

Methods

Relations between pedestrians´ perceptions of four traffic variables and appraisals of route environments as hindering – stimulating for walking as well as unsafe – safe for reasons of traffic, were therefore studied in the inner urban area of Stockholm, Sweden (n = 294). The pedestrians rated their perceptions and appraisals with the Active Commuting Route Environment Scale (ACRES). Correlation, multiple regression, and mediation analyses were used to study the relationships between the traffic variables and the outcome variables. 

Results 

Noise related negatively to both hindering – stimulating for walking, and to unsafety – safety for traffic reasons. Vehicle speed related negatively to unsafety – safety for traffic reasons. Furthermore, vehicle speed protruded as an important origin of the deterring effects of traffic among those who commute by foot. 

Conclusion

The study shows the value of both partial and simultaneous analyses of the effect of all four traffic variables in relation to outcome variables relevant for walking. 

Background: Quantification of movement intensity and energy utilization, together with frequency of trips, duration, distance, step counts and cadence, is essential for interpreting the character of habitual walking for transport, and its potential support of health. The purpose of the study is to illuminate this with valid methods and novel perspectives, and to thereby provide a new basis for characterizing and interpreting walking in relation to health outcomes.

Methods: Habitual middle-aged commuting pedestrians (males = 10, females= 10) were investigated in the laboratory at rest and with maximal treadmill and cycle ergometer tests. Thereafter, levels of oxygen uptake, energy expenditure, ventilation, heart rate, blood lactate, rated perceived exertion, cadence, number of steps, duration, distance, and speed were recorded during the normal walking commute of each participant in Greater Stockholm, Sweden. The number of commutes per week over the year was self-reported.

Results: Walking in the field demanded about 30% more energy per km compared to level treadmill walking. For both sexes, the walking intensity in field was about 46% of maximal oxygen uptake, and energy expenditure amounted to 0.96 kcal · kg−1 · km−1. The MET values (males: 6.2; females:6.5) mirrored similar levels of walking speed (males: 5.7; females: 5.9 km · h−1) and levels of oxygen uptake (males: 18.6; females: 19.5mL · kg−1 · min−1). The average number of MET-hours per week in a typical month was 22 for males and 20 for females. This resulted in a total weekly energy expenditure of∼1,570 and 1,040 kcal for males and females, respectively. Over the year, the number of walking commutes and their accumulated distance was ∼385 tripsand 800 km for both sexes.

Conclusion: Walking in naturalistic field settings demands its own studies. When males and females walk to work, their relative aerobic intensities and absolute energy demands for a given distance are similar. It is equivalent to the lower part of the moderate relative intensity domain.The combination of oxygen uptake, trip duration and frequency leads to high and sustained levels of MET-hours as well as energy expenditure per week over the year, with a clear health enhancing potential. Based on this study we recommend 6000 transport steps per day, or equivalent, during five weekdays, over the year, in order to reach optimal health gains.

BACKGROUND: The heart rate (HR) method enables estimating oxygen uptake (V̇O₂) in physical activities. However, there is a paucity in knowledge about the interchangeability of this method when applied to cycling, walking and running. Furthermore, with the aim of optimization, there is a need to compare different models for establishing HR-V̇O₂ relationships.

METHODS: Twenty-four physically active individuals (12 males and 12 females) participated. For each participant, two models of HR-V̇O₂ relationships were individually established in ergometer cycling, level treadmill walking and running. Model 1 consisted of five submaximal workloads, whereas model 2 included also a maximal workload. Linear regression equations were used to estimate V̇O₂ at seven intensity levels ranging between 25 and 85% of heart rate reserve (HRR). The estimated V̇O₂ levels were compared between the exercise modalities and models, as well as with data from a previous study.

RESULTS: A high level of resemblance in estimated V̇O₂ was noted between running and cycling as well as between running and walking, with both model 1 and model 2. When comparing walking and cycling, the V̇O₂ levels for given intensities of %HRR were frequently slightly higher in walking with both models (range of significant differences: 5-12%). The variations of the estimated individual V̇O₂ values were reduced when using model 2 compared to model 1, both between and within the exercise modalities.

CONCLUSION: The HR method is optimized by more workloads and wider ranges. This leads to overall high levels of interchangeability when HR methods are applied in ergometer cycling, level treadmill walking and running.

Purpose: Quantifying intensities of physical activities through measuring oxygen uptake (V̇O₂) is of importance for understanding the relation between human movement, health and performance. This can in principle be estimated by the heart rate (HR) method, based on the linear relationship between HR and V̇O₂ established in the laboratory. It needs, however, to be explored whether HR methods, based on HR-V̇O₂ relationships determined in the laboratory, are valid for estimating spectrums of V̇O₂ in field exercise. We hereby initiate such studies, and use cycle commuting as the form of exercise.

Methods: Ten male and ten female commuter cyclists underwent measurements of HR and V̇O₂ while performing ergometer cycling in a laboratory and a normal cycle commute in the metropolitan area of Stockholm County, Sweden. Two models of individual HR-V̇O₂ relationships were established in the laboratory through linear regression equations. Model 1 included three submaximal work rates, whereas model 2 also involved a maximal work rate. The HR-V̇O₂ regression equations of the two models were then used to estimate V̇O₂ at six positions of field HR: five means of quintiles and the mean of the whole commute. The estimations obtained were for both models compared with the measured V̇O₂.

Results: The measured quintile range during commuting cycling was about 45-80% of V̇O₂max. Overall, there was a high resemblance between the estimated and measured V̇O₂, without any significant absolute differences in either males or females (range of all differences: -0.03-0.20 L⋅min^-1). Simultaneously, rather large individual differences were noted.

Conclusion: The present HR methods are valid at group level for estimating V̇O₂ of cycle commuting characterized by relatively wide spectrums of exercise intensities. To further the understanding of the external validity of the HR method, there is a need for studying other forms of field exercises.

Introduction. The heart rate (HR) method is a promising approach for evaluating oxygen uptake (V̇O₂), energy demands and exercise intensities in different forms of physical activities. It would be valuable if the HR method, established on ergometer cycling, is interchangeable with other regular activities, such as level walking. This study therefore aimed to examine the interchangeability of the HR method when estimating V̇O₂ for ergometer cycling and level treadmill walking in submaximal conditions. 

Methods. Two models of HR-V̇O₂ regression equations for cycle ergometer exercise (CEE) and treadmill exercise (TE) were established with 34 active commuters. Model 1 consisted of three submaximal intensities of ergometer cycling or level walking, model 2 included also one additional workload of maximal ergometer cycling or running. The regression equations were used for estimating V̇O₂ with seven individual HR values based on 25-85% of HR reserve (HRR). The V̇O₂ estimations were compared between CEE and TE, within and between each model.

Results. Only minor, and in most cases non-significant, average differences were observed when comparing the estimated V̇O₂ levels between CEE and TE. Model 1 ranged from -0.4 to 4.8% (n.s.) between 25-85 %HRR. In model 2, the differences between 25-65 %HRR ranged from 1.3 to -2.7% (n.s.). At the two highest intensities, 75 and 85 %HRR, V̇O₂ was slightly lower (3.7%, 4.4%; P < 0.05), for CEE than TE. The inclusion of maximal exercise in the HR-V̇O₂ relationships reduced the individual V̇O₂ variations between the two exercise modalities.

Conclusion. The HR methods, based on submaximal ergometer cycling and level walking, are interchangeable for estimating mean V̇O₂ levels between 25-85% of HRR. Essentially, the same applies when adding maximal exercise in the HR-V̇O₂ relationships. The inter-individual V̇O₂ variation between ergometer cycling and treadmill exercise is reduced when using the HR method based on both submaximal and maximal workloads.