The Influence of the Inter-Relationship of Leg Position and Riding Posture on Cycling Aerodynamics

Aerodynamics is an important factor affecting cyclist performance, as at the elite level 90% of rider energy is used to overcome aerodynamic drag. As such, much effort has been channeled into understanding the detailed flow around cyclists, since small gains can produce large rewards. Previous studies have shown that cycling aerodynamic drag is sensitive to leg position during the pedaling cycle; however, a systematic analysis comparing the impact of leg position between different riding postures is yet to be undertaken. To address this question, we compare the impact of leg position for two elite-level riding postures: the standard sprint and pursuit body positions. The comparison shows that the effect of leg position on drag is not consistent between the two riding postures, as the altered flow associated with different leg positions is influenced by the wakes from and proximity of other upstream or nearby components, such as the arms. This study reveals the inter-relationship between leg position and riding posture; and suggests that the flow associated with varied leg position should include surrounding geometrical components to obtain and understand the full aerodynamic impact. Practically, the results are valuable for optimizing the posture and improving skin-suit design for drag minimization.

Reliability of the Hip Extension Lower Exercise as a Measure of Eccentric Hamstring Strength

Hamstring strain injury (HSI) is a very common lower-body injury in field sports, and eccentric (ECC) hamstring strength is a potential modifiable risk factor, therefore having reliable eccentric hamstring strength assessments is critical. The aim of this study was to access test–retest reliability of the hip extension lower (HEL) exercise as a measure of ECC hamstring strength and inter-limb asymmetries. Twelve male elite level soccer players (mean; age: 21.8 years; height: 180.4 cm; weight: 75.7 kg) volunteered to participate in this study. Participants were from the same soccer club, covered all playing positions, and had no current injury issues. Participants performed two familiarization sessions to acquaint themselves with the device and exercise protocol. During testing, each participant performed three repetitions with 60s intra-set recovery provided. Average and peak force (N) was recorded for both limbs. Testing sessions took place on the same day and time over a two-week pre-season period and followed a full recovery day. Intraclass Correlation Coefficient (ICC), Coefficient of Variation (CV%), Minimal Detectable Change (MDC) and Typical Error (TE) were used to assess reliability. The HEL showed excellent reliability for average force (N) in the left (ICC (95% CI) = 0.9 (0.7–0.97); TE = 14.1 N, CV% = 1.87; MDC = 39.06 N) and right (ICC (95% CI) = 0.91 (0.73–0.97); TE = 20.89 N, CV% = 3.26; MDC = 57.87 N) limb, and also excellent reliability for peak force in the left (ICC (95% CI) = 0.91 (0.71–0.97); TE = 13.55 N, CV% = 1.61; MDC = 57.87 N) and right (ICC (95% CI) = 0.9 (0.7–0.97); TE = 21.70 N, CV% = 3.31; MDC = 60.11 N) limb. This data suggests the HEL as a reliable measure of both ECC hamstring strength and inter-limb asymmetries. Practitioners should consider the HEL as a reliable choice for measuring and monitoring eccentric hamstring strength in their athletes.

Rewiring Linked Fate: Bringing Back History, Agency, and Power

Linked fate, the concept introduced by Dawson almost three decades ago, reoriented the study of racism and political behavior in the United States. The scholarship traditionally had focused on the racial psychology of whites and how racism seeps into their political views and actions. Dawson proposed the Black utility heuristic theory and linked fate, its associated measure, to investigate the political behavior of Blacks, the minority group most harmed by racism. Since then, linked fate has become a ubiquitous variable of interest in research on minority group politics. Yet the research program around linked fate is due for some extension. Most studies gloss over the fact that the Black utility heuristic theory is historically and socially conditional. We call for bringing elite-level agency and group-level social practices back into the literature to clarify the macro- and meso-level conditions under which a group’s racial status translates into linked fate at the individual level. Greater inquiry into these dynamics is not only warranted but also has broad implications for the research on racial and ethnic politics.

Influence of COVID-19 Restrictions on Training and Physiological Characteristics in U23 Elite Cyclists

PURPOSE: The COVID-19 pandemic and its associated mobility restrictions caused many athletes to adjust or reduce their usual training load. The aim of this study was to investigate how the COVID-19 restrictions affected training and performance physiology measures in U23 elite cyclists. METHODS: Twelve U23 elite cyclists (n = 12) participated in this study (mean ± SD: Age 21.2 ± 1.2 years; height 182.9 ± 4.7 cm; body mass 71.4 ± 6.5 kg). Training characteristics were assessed between 30 days pre, during, and post COVID-19 restrictions, respectively. The physiological assessment in the laboratory was 30 days pre and post COVID-19 restrictions and included maximum oxygen uptake (V̇O2max), peak power output for sprint (SprintPmax), and ramp incremental graded exercise (GXTPmax), as well as power output at ventilatory threshold (VT) and respiratory compensation point (RCP). RESULTS: Training load characteristics before, during, and after the lockdown remained statistically unchanged (p > 0.05) despite large effects (>0.8) with mean reductions of 4.7 to 25.0% during COVID-19 restrictions. There were no significant differences in maximal and submaximal power outputs, as well as relative and absolute V̇O2max between pre and post COVID-19 restrictions (p > 0.05) with small to moderate effects. DISCUSSION: These results indicate that COVID-19 restrictions did not negatively affect training characteristics and physiological performance measures in U23 elite cyclists for a period of <30 days. In contrast with recent reports on professional cyclists and other elite level athletes, these findings reveal that as long as athletes are able to maintain and/or slightly adapt their training routine, physiological performance variables remain stable.

Recent COVID-19 vaccination has minimal effects on the physiological responses to graded exercise in physically active healthy people

Athletes are advised to receive the COVID-19 vaccination to protect them from SARS CoV-2 infection during major competitions. Despite this, many athletes are reluctant to get the COVID-19 vaccine due to concerns that symptoms of vaccinosis may impair athletic performance. OBJECTIVE: To determine the effects of COVID-19 vaccination on the physiological responses to graded exercise. METHODS: Healthy physically active participants completed a 20-minute bout of graded cycling exercise at intensities corresponding to 50, 60, 70 and 80% of the pre-determined V̇O2max before and ~21 days after receiving the COVID-19 vaccine (2 dose Pfizer mRNA or 1 dose Johnson&Johnson). RESULTS: Vaccination had no effect on a large number of physiological responses to exercise measured in blood (e.g. lactate, epinephrine, cortisol) and by respiratory gas exchange (e.g. oxygen uptake, CO2 production, ventilation, respiratory exchange ratio, predicted V̇O2max, ventilatory threshold) (p>0.05). We did, however, find significant elevations in heart rate (~5 bpm) and norepinephrine (p = 0.006 and 0.04, respectively) in response to vigorous (e.g. 70-80% V̇O2max) intensity exercise after vaccination, particularly in those that received the two shot Pfizer mRNA vaccine regimen. These findings held true when compared to demographically matched controls who completed identical bouts of exercise several weeks apart without receiving a vaccine. CONCLUSION: Recent COVID-19 vaccination has minimal effects on the physiological responses to graded exercise in physically active healthy people. The small elevations in cardiovascular and neuroendocrine responses to exercise after the Pfizer mRNA vaccine regimen could have implications for athletes at the elite level and warrants investigation.

The nonlinear feedback dynamics of asymmetric political polarization

Using a general model of opinion dynamics, we conduct a systematic investigation of key mechanisms driving elite polarization in the United States. We demonstrate that the self-reinforcing nature of elite-level processes can explain this polarization, with voter preferences accounting for its asymmetric nature. Our analysis suggests that subtle differences in the frequency and amplitude with which public opinion shifts left and right over time may have a differential effect on the self-reinforcing processes of elites, causing Republicans to polarize more quickly than Democrats. We find that as self-reinforcement approaches a critical threshold, polarization speeds up. Republicans appear to have crossed that threshold while Democrats are currently approaching it.

Injuries in Elite Men’s Rugby Union: An Updated (2012–2020) Meta-Analysis of 11,620 Match and Training Injuries

Background The most recent meta-analytic review of injuries in elite senior men’s Rugby Union was published in 2013. The demands of the game at the elite level are continually changing alongside law amendments and developments in player preparation. As such, an updated meta-analysis of injury data in this setting is necessary. Objective To meta-analyse time-loss injury data in elite senior men’s Rugby Union between 2012 and 2020. Methods Electronic databases were searched using the keywords ‘rugby’ and ‘inj*’. Nineteen studies met the inclusion criteria. Injury incidence rate data were modelled using a mixed-effects Poisson regression model. Days missed data were modelled using a general linear mixed model. Results The included data encompassed a total of 8819 match injuries and 2801 training injuries. The overall incidence rate of injuries in matches was 91 per 1000 h (95% confidence interval (CI) 77–106). The estimated mean days missed per match injury was 27 days (95% CI 23–32). The overall incidence rate of match concussions was 12 per 1000 h (95% CI 9–15). The overall incidence rate of training injuries was 2.8 per 1000 h (95% CI 1.9–4.0). Playing level was not a significant effect modifier for any outcome. Conclusions The injury incidence rate and mean days missed per injury in the present meta-analysis were higher, but statistically equivalent to, the 2013 meta-analysis (81 per 1000 h and 20 days, respectively). The injury incidence rate for match injuries in elite senior men’s Rugby Union is high in comparison to most team sports, though the training injury incidence rate compares favourably. The tackle event and concussion injuries should continue to be the focus of future preventative efforts.

Relationship Between Yo-Yo Intermittent Endurance Test-Level 1 and Match Running Performance in Soccer: Still on the Right Path?

Introduction. The Yo-Yo Intermittent Endurance Test-Level 1 (Yo-Yo IR1) is considered a valuable measurement tool in assessing specific soccer endurance. However, there is a lack of recent research validating this test with regard to match running performance (MRP) in elite-level soccer. Material and Methods. The aim of this study was to evaluate the validity of Yo-Yo IR1 in predicting MRP during elite-level soccer matches. The participants were soccer players who competed in the highest-level Croatian soccer league (23.57 ± 2.84 years, 181.9 ± 5.17 cm, 78.36 ± 4.18 kg), and they were all tested using Yo-Yo IR1 in the middle of the season 2019/2020. The players’ MRP (n = 71) was measured using the Global Positioning System over one-half season, and included the total distance covered, the distance covered in different speed zones, accelerations and decelerations. The association between MRP and Yo-Yo IR1 was identified with Pearson’s correlation. Results. The results indicated that central midfielders and fullbacks achieved significantly higher results in Yo-Yo IR1 than forwards and central defenders (F-test: 29.80; p < 0.01; large effect size). Higher results in Yo-Yo IR1 were correlated with the match amount of (i) the total distance covered (r = 0.65); (ii) high-speed running (r = 0.42); (iii) high-intensity distance covered (r = 0.36); (iv) total accelerations (r = 0.37); and total decelerations (r = 0.42). Conclusions. The established associations between Yo-Yo IR1 and MRP in this study confirmed the validity of Yo-Yo IR1 in predicting MRP in professional soccer today.

Accuracy and Reliability of Inertial Devices for Load Assessment During Flywheel Workout

There is currently an increase in inertial flywheel application in strength training; thus, it must be monitored by an accurate and reliable device. The present study tested: (1) the accuracy of an inertial measurement device (IMU) to correctly measure angular velocity and (2) its inter-unit reliability for the measurement of external load. The analysis was performed using Pearson Correlation and Intraclass Correlation Coefficient (ICC). The IMU accuracy was tested using Bland-Altman and the reliability with the coefficient of variation (CV). Ten elite-level football players performed ten series of 5 repetitions in a one-hand standing row exercise (5 series with each arm). A nearly perfect accuracy (ICC=.999) and a very good between-device reliability (Bias=-.010; CV=.017%) was found. IMU is a reliable and valid device to assess angular velocity in inertial flywheel workout objectively.