The running shoe has gone through significant changes since its inception. The purpose of this paper is to review these changes, the majority of which have occurred over the past 50 years. Running ...footwear began as very minimal, then evolved to become highly cushioned and supportive. However, over the past 5 years, there has been a reversal of this trend, with runners seeking more minimal shoes that allow their feet more natural motion. This abrupt shift toward footwear without cushioning and support has led to reports of injuries associated with minimal footwear. In response to this, the running footwear industry shifted again toward the development of lightweight, partial minimal shoes that offer some support and cushioning. In this paper, studies comparing the mechanics between running in minimal, partial minimal, and traditional shoes are reviewed. The implications for injuries in all 3 conditions are examined. The use of minimal footwear in other populations besides runners is discussed. Finally, areas for future research into minimal footwear are suggested.
The purpose of this study was to examine the effects of step length and foot strike pattern along with their interaction on tibiofemoral joint (TFJ) and medial compartment TFJ kinetics during ...running. Nineteen participants ran with a rear foot strike pattern at their preferred speed using a short (−10%), preferred, and long (+10%) step length. These step length conditions were then repeated using a forefoot strike pattern. Regardless of foot strike pattern, a 10% shorter step length resulted in decreased peak contact force, force impulse per step, force impulse per kilometre, and average loading rate at the TFJ and medial compartment, while a 10% increased step length had the opposite effects (all P < 0.05). A forefoot strike pattern significantly lowered TFJ and medial compartment TFJ average loading rates compared with a rear foot strike pattern (both <0.05) but did not change TFJ or medial compartment peak force, force impulse per step, or force impulse per km. The combination of a shorter step length and forefoot strike pattern produced the greatest reduction in peak medial compartment contact force (P < 0.05). Knowledge of these running modification effects may be relevant to the management or prevention of TFJ injury or pathology among runners.
Ultra-endurance running (UER) has seen an important increase in participation over the last few decades. Long hours of UER can lead to excessive stress on the body, resulting in musculoskeletal ...injuries (MSKI). UER is not a uniform sport and events can differ considerably in distance (over 42.195 km), time (e.g., events over 6 h) and multi-day or multi-stage events on various surfaces (e.g., track, on-road, off-road). The aims of this scoping review were therefore: (1) to examine the current evidence of MSKI, providing a synthesis of the most common MSKI by anatomical region and specific diagnosis; (2) categorize MSKI by type of UER activity (competition: time-limited; multi-stage; continuous UER events and training); (3) describe knowledge gaps in the literature and provide advice on potential further research. Our electronic literature search (PubMed, SPORTDiscus, Web of Science) identified a total of 13 studies (9 in competition, and 4 in training). Anatomical site, diagnosis and rate of injuries differ between competition and training as well as between different UER types. MSKI are observed in 18% of multi-stage events (0.7-1.8 injuries/runner and 7.2 injuries/1000 h). Most MSKI involve the lower leg (35.0%), ankle (16.8%), knee (13.1%) and foot (12.6%), with main diagnosis of medial tibial stress syndrome (30.1%) and patella femoral pain syndrome (PFPS; 7.2%). Single, continuous UER events differ between a 1005 km road race with almost all of the injuries due to overuse, with the main anatomical site of the knee (31%), ankle (28%) and lower leg (14%) and main diagnosis of PFPS (15.6%), compared to a 65 km trail race, with 32.8% of MSKI, mainly on the foot plantar fasciitis (28.6%), ankle sprain (28.6%) and knee. Timed-UER events (injury rate of 2.1 injuries/athlete) observed most injuries on the ankle (36%) and knee (19%), with the main diagnosis of tendinitis of the foot dorsiflexors (30%). Injuries during training most commonly affect, the back (42%), and knee (40%) and bone stress injuries (22%). Main diagnoses include ankle sprain (18%), iliotibial band injury (16%) and Achilles tendinopathy (11%). Future considerations include examining MSKI in different UER events, environments and surfaces, and on larger study populations. Establishing risk factors, examining sex differences and using a standard reporting system of MSKI in UER are also important.
Producing comparable/greater ground reaction forces (GRFs) at faster running speeds is beneficial for sprint performance, and assisted sprint training is used to induce faster running speed ...conditions. This study aimed to demonstrate the characteristics of assisted sprinting at the maximal speed phase and investigate acute differences to control sprinting. Fifteen sprinters completed control and assisted (5 kg) sprints over force platforms. Assisted sprinting increased running speed (9.3% mean difference), while propulsive mean force (−4.3%) and impulse (−12.4%) decreased, suggesting that running speed improvements were caused primarily by assisted pulling force rather than improvements in anteroposterior force production of athletes. In addition, vertical mean force increased (4.2%), probably due to braking mean force (34.2%) and impulse (32.5%) increases. Magnitude of control trial maximum speed was achieved earlier (during acceleration) in assisted trials, and net anteroposterior (includes both braking and propulsive components) mean force (67.2%) and impulse (67.9%) increased at this matched speed, suggesting that assisted sprints could be used to practice producing greater GRFs at comparable speeds. Running speed improvement by pulling force was associated with contact time decreases (r = -.565), suggesting that shortening contact time may be important for effective assisted sprinting.
Aerobic capacity is crucial for the performance of soccer players; however, the relationship between VOsub.2max and the running performance of soccer players with visual impairment is not known. ...Possibly finding relationships would help in the training process, as training would be more targeted. Additionally, both bodyweight and relative VO2max are factors that affect people’s health and wellness. From the literature, it appears that there are no studies that present the normal profile of soccer players with visual impairment. The aims of this study were to (a) determine the differences in VOsub.2max between soccer players and sedentary men with visual impairment; (b) to assess the relationship between the VOsub.2max of players with visual impairment and the distance covered in a soccer match and (c) to describe a profile of physiological parameters and distance running during a soccer match. Six male soccer players with VI and six male sedentary people with VI participated in this study. Anthropometric characteristics (age, height, bodyweight, body fat (BF), body mass index (BMI), cardiorespiratory markers (VOsub.2max, maximum heart rate (HRmax), respiratory exchange ratio (RER)) and the running performance of soccer players during matches were measured, and the VOsub.2max of all the participants was measured in a laboratory. Mann–Whitney U test was used to evaluate differences between sedentary and soccer players’ anthropometric characteristics and performance. A correlation analysis by Spearman’s’ method was used to examine relationships between VOsub.2max and the rest of the physical values during the match. The level of statistical significance was set at p < 0.05. The soccer players’ weight was 33% lower, and their BMI was 23% lower than that of sedentary men (p = 0.023, ηsup.2 = 0.457 and p = 0.048, ηsup.2 = 0.394, respectively). The relative body mass VOsub.2max of the athletes was 42.9% higher in comparison with sedentary men with VI (p = 0.002, ηsup.2 = 0.755). No correlations were found between VOsub.2max and match running performance (p = 0.957, r = −0.029) or other parameters during the match in soccer players with VI. In conclusion, relative VOsub.2max is not related to the match running performance of soccer players. The tactics applied by the team, the style of play and the position of the player may affect the distances covered. Also, as expected, the soccer players showed lower bodyweight and higher relative VOsub.2max. However, this is the first study to observe the level of these differences.
•An extraordinary distance runner completed 100 marathons in equal days.•The marathoner had remarkably low loading-related magnitudes, for example, peak ground reaction forces and loading rates, that ...were associated with a remarkably high duty factor. The low vertical loading rate can be partially explained by a pronounced rearfoot strike.•Monitoring of the case revealed an increase in bone mineral density while the loading-related magnitudes showed no clear change.•The pattern of the successful high-mileage runner may be useful when developing or evaluating load-shifting strategies in distance running.
An extraordinary long-term running performance may benefit from low dynamic loads and a high load-bearing tolerance. An extraordinary runner (age = 55 years, height = 1.81 m, mass = 92 kg) scheduled a marathon a day for 100 consecutive days. His running biomechanics and bone density were investigated to better understand successful long-term running in the master athlete.
Overground running gait analysis and bone densitometry were conducted before the marathon-a-day challenge and near its completion. The case's running biomechanics were compared pre-challenge to 31 runners who were matched by a similar foot strike pattern.
The case's peak vertical loading rate (Δx̄ = –61.9 body weight (BW)/s or –57%), peak vertical ground reaction force (Δx̄ = –0.38 BW or –15%), and peak braking force (Δx̄ = –0.118 BW or –31%) were remarkably lower (p < 0.05) than the control group at ∼3.3 m/s. The relatively low loading-related magnitudes were attributed to a remarkably high duty factor (0.41) at the evaluated speed. The foot strike angle of the marathoner (29.5°) was greater than that of the control group, affecting the peak vertical loading rate. Muscle powers in the lower extremity were also remarkably low in the case vs. controls: peak power of knee absorption (Δx̄ = –9.16 watt/kg or –48%) and ankle generation (Δx̄ = –3.17 watt/kg or –30%). The bone mineral density increased to 1.245 g/cm² (+2.98%) near completion of the challenge, whereas the force characteristics showed no statistically significant change.
The remarkable pattern of the high-mileage runner may be useful in developing or evaluating load-shifting strategies in distance running.
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Thermal comfort is one of the most important factors for satisfying occupants within indoor environments, especially in regions that experience warm summer seasons, and analyses of thermal comfort ...and occupant behaviour are critical for the effective implementation of energy saving programs. This paper presents the results of studies on the thermal comfort and adaptive behaviour of occupants in university buildings with free running (FR) and cooling (CL) mode offices in Fukuoka, Japan. Both thermal measurements and thermal comfort surveys were conducted during the summer season. The mean thermal sensation vote (TSV) in FR and CL modes was 0.7 and −0.1, respectively. These data show that occupants in FR mode offices felt slightly warmer than those in CL mode offices, where occupants typically reported feeling neutral. The mean comfort temperature for both cases, as estimated by using the Griffiths method, was 26.6 °C. For personal clothing, we found that the use of clothing insulation was inversely proportional to the outdoor temperature. The adaptive behaviours of occupants were found to be more active in FR mode offices compared to those in CL mode offices, which were more passive. This indicates that amenable thermal conditions were present in the air conditioning (A/C)-controlled indoor environments where occupants expressed no wish to make changes.
•Thermal comfort and occupant behaviour in offices with FR and CL modes was studied.•The mean comfort temperature obtained for both FR and CL modes was 26.6 °C.•Occupants in FR mode offices frequently adapted to heat discomfort by taking drinks.•Fan usage behaviour was higher (19%) for the FR mode compared to the CL mode (5%).
Purpose
To reduce inflow and motion artifacts in free‐breathing, free‐running, steady‐state spoiled gradient echo T1‐weighted (SPGR) myocardial perfusion imaging.
Method
Unsaturated spins from ...inflowing blood or out‐of‐plane motion cause flashing artifacts in free‐running SPGR myocardial perfusion. During free‐running SPGR, 1 non‐selective RF excitation was added after every 3 slice‐selective RF excitations to suppress inflow artifacts by forcing magnetization in neighboring regions to steady‐state. Bloch simulations and phantom experiments were performed to evaluate the impact of the flip angle and non‐selective RF frequency on inflowing spins and tissue contrast. Free‐running perfusion with (n = 11) interleaved non‐selective RF or without (n = 11) were studied in 22 subjects (age = 60.2 ± 14.3 years, 11 male). Perfusion images were graded on a 5‐point Likert scale for conspicuity of wall enhancement, inflow/motion artifact, and streaking artifact and compared using Wilcoxon sum‐rank testing.
Result
Numeric simulation showed that 1 non‐selective RF excitation applied after every 3 slice‐selective RF excitations produced superior out‐of‐plane signal suppression compared to 1 non‐selective RF excitation applied after every 6 or 9 slice‐selective RF excitations. In vitro experiments showed that a 30° flip angle produced near‐optimal myocardial contrast. In vivo experiments demonstrated that the addition of interleaved non‐selective RF significantly (P < .01) improved conspicuity of wall enhancement (mean score = 4.4 vs. 3.2) and reduced inflow/motion (mean score = 4.5 vs. 2.5) and streaking (mean score = 3.9 vs. 2.4) artifacts.
Conclusion
Non‐selective RF excitations interleaved between slice‐selective excitations can reduce image artifacts in free‐breathing, ungated perfusion images. Further studies are warranted to assess the diagnostic accuracy of the proposed solution for evaluating myocardial ischemia.
•This study examines the impact of daytime running light (non)use on the estimation of motorcycle speed.•There is a difference in the estimation of motorcycle speed when DRL are on/off and when DRL ...are on with LED systems.•The use of LED DRL system has a greater contribution to the perception of motorcycle speed on roads with higher speed limits.•The driving license category and the frequency of driving have an impact on the accurate assessment of motorcycle speed.
Motorcycles are the most common type of vehicle involved in traffic deaths, especially in underdeveloped and developing countries. In order to prevent traffic accidents involving motorcyclists, one of the measures is to respect the “see and be seen” rule. If a motorcycle is perceived in time or another motorcyclist is spotted in time, there is enough time to react, in order to avoid a traffic accident or reduce the consequences. In many countries, it is for this reason that the use of daytime running lights on motor vehicles and/or motorcycles is legally prescribed. In the Republic of Serbia, a country that belongs among the least developed countries, about a third of those killed in traffic accidents are motorcycle drivers. For these reasons, an experimental study was conducted on a driving simulator to examine the importance of (non) use of daytime running lights on the estimation of motorcycle speed. Three different situations were examined: without daytime running lights, with daytime running lights, and with LED daytime running lights; for test speeds of 30 km/h, 50 km/h, 70 km/h, and 90 km/h. In the experiment, 128 young drivers participated. The results showed that the speed of a motorcycle with LED daytime running lights on is perceived most accurately.
Background Investigation into strenuous activity and kidney function has gained interest given increasing marathon participation. Study Design Prospective observational study. Setting & Participants ...Runners participating in the 2015 Hartford Marathon. Predictor Completing a marathon. Outcomes Acute kidney injury (AKI) as defined by AKI Network (AKIN) criteria. Stage 1 AKI was defined as 1.5- to 2-fold or 0.3-mg/dL increase in serum creatinine level within 48 hours of day 0 and stage 2 was defined as a more than 2- to 3-fold increase in creatinine level. Microscopy score was defined by the number of granular casts and renal tubular epithelial cells. Measurements Samples were collected 24 hours premarathon (day 0), immediately postmarathon (day 1), and 24 hours postmarathon (day 2). Measurements of serum creatinine, creatine kinase, and urine albumin were completed, as well as urine microscopy analysis. 6 injury urine biomarkers (IL-6, IL-8, IL-18, kidney injury molecule 1, neutrophil gelatinase-associated lipocalin, and tumor necrosis factor α) and 2 repair urine biomarkers (YKL-40 and monocyte chemoattractant protein 1) were measured. Results 22 marathon runners were included. Mean age was 44 years and 41% were men. 82% of runners developed an increase in creatinine level equivalent to AKIN-defined AKI stages 1 and 2. 73% had microscopy diagnoses of tubular injury. Serum creatinine, urine albumin, and injury and repair biomarker levels peaked on day 1 and were significantly elevated compared to day 0 and day 2. Serum creatine kinase levels continued to significantly increase from day 0 to day 2. Limitations Small sample size and limited clinical data available at all time points. Conclusions Marathon runners developed AKI and urine sediment diagnostic of tubular injury. An increase in injury and repair biomarker levels suggests structural damage to renal tubules occurring after marathon. The results of our study should be validated in larger cohorts with longer follow-up of kidney function.
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