Background: There is limited insight into the mechanisms of anterior cruciate ligament injuries in alpine skiing, particularly among professional ski racers.

The increased awareness for the environment and steadily higher costs for gasoline makes bicycles more and more attractive for short-distance traffic. Due to this the infrastructure of cycling pathways gets more important not only for safety reasons but also for the aspect of cycling (dis)comfort. Comfortable cycling requires smooth rolling at lowest possible energy input. To better understand this relationship, the objective of the study was to determine rolling resistance and the resulting accelerations due to external agitations for different surfaces. Rolling resistance was quantified using a one degree of freedom pendulum (transversal rotation). By setting it at an initial angular displacement the measured decay of oscillations is a direct measure for the rolling resistance. To investigate the vibrations, an accelerometer was applied under the seat of a racing bicycle. The cyclist had to roll over a distance of 15 m at 3 different velocities with no pedaling. Four different surfaces were investigated. An effective value factor was defined for an overall description of the observed data. The covered distance of the pendulum is directly related to the rolling resistance and varied from 22,1 m on concrete slabs to 10,2 m on cobblestones. Asphalt and self-binding gravel rank in between. This ranking however changes when analyzing the vibrations. Lowest effective value factors were measured on asphalt (0, 05) whereas concrete slabs (0, 17), self-binding gravel (0, 21) and cobblestones (0, 57) are far behind. Comfort decreases with higher velocities. The results of this study allow suggestions about the best surface for cycling pathways thus making the systematic design of comfortable bicycle lanes easier. Designing bike lanes for comfort is an important issue to persuade more people to use the bike, especially the elderly population

Purpose: – The purpose of this paper is to understand the difference in purchase decision behavior of compression sportswear by Baby Boomers and Generation Y. Design/methodology/approach: – Two methods were used for data collection: a simulation study with 17 Baby Boomers and 23 Generation Y subjects using eye-tracking technology; and a questionnaire from a sample of 82 Baby Boomers and 84 Generation Y consumers. Findings: – Generation Y are more inquisitive and focus greatly on technical information. Baby Boomers are more confident with their choices, taking a shorter time to reach a purchase decision; they are more concerned with aspects that protect the wearer. Research limitations/implications: – Limited demographic information was collected from participants in the simulation study, further research is required in this area. Practical implications: – This study provides important insights into the purchase decision behavior of Baby Boomers and Generation Y for compression sportswear. By providing better understanding of some of the key drivers for purchase decisions it enables marketers to develop more effective marketing plans to engage with these important consumer groups. Social implications: – The focus and findings of this study provide further understanding of the motivations of two significant consumer cohorts. This study provides further momentum to the body of cohort research already available. Originality/value: – This study addresses a gap in literature with reference to the comparison of consumer behavior of generational cohorts when purchasing compression sportswear. Findings can be applied in other areas of sportswear and to other countries.

Heart rate measurement has become one of the most widely used methods of monitoring the intensity of physical activity. The purpose of this study was to assess whether in-ear photoplethysmographic (PPG) pulse rate (PR) measurement devices represent a valid alternative to heart rate derived from electrocardiography (ECG), which is considered a gold standard. Twenty subjects (6 women, 14 men) completed one trial of graded cycling under laboratory conditions. In the trial, PR was recorded by two commercially available in-ear devices, the Dash Pro and the Cosinuss°One. They were compared to HR measured by a Bodyguard2 ECG. Validity of the in-ear PR measurement devices was tested by ANOVA, mean absolute percentage errors (MAPE), intra-class correlation coefficient (ICC), and Bland–Altman plots. Both devices achieved a MAPE ≤5%. Despite excellent to good levels of agreement, Bland–Altman plots showed that both in-ear devices tend to slightly underestimate the ECG’s HR values. It may be concluded that in-ear PPG PR measurement is a promising technique that shows accurate but imprecise results under controlled conditions. However, PPG PR measurement in the ear is sensitive to motion artefacts. Thus, accuracy and precision of the measured PR depend highly on measurement site, stress situation, and exercise.

Activity trackers are a simple and mostly low-priced method to capture physiological parameters. Despite the high number of wrist-worn devices, there is a lack of scientific validation. The purpose of this study was to assess whether the activity trackers represent a valid alternative to gold-standard methods in terms of estimating energy expenditure (EE) and maximum oxygen uptake (VO_2max). Twenty-four healthy subjects participated in this study. In total, five commercially available wrist-worn devices were tested with regard to their validity of EE and/or VO_2max. Estimated values were compared with indirect calorimetry. Validity of the activity trackers was determined by paired sample t-tests, mean absolute percentage errors (MAPE), Intraclass Correlation Coefficient, and Bland-Altman plots. Within the tested devices, differences in scattering in VO_2max and EE could be observed. This results in a MAPE > 10% for all evaluations, except for the VO_2max-estimation of the Garmin Forerunner 920XT (7.3%). The latter significantly underestimates the VO_2max (t(23) = –2.37, p = 0.027), whereas the Garmin Vivosmart HR significantly overestimates the EE (t(23) = 2.44, p = 0.023). The tested devices did not show valid results concerning the estimation of VO_2max and EE. Hence, the current wrist-worn activity trackers are most likely not accurate enough to be used for neither purposes in sports, nor in health care applications.