The Future of Graphene: Preparation from Biomass Waste and Sports Applications.

At present, the main raw material for producing graphene is graphite ore. However, researchers actively seek alternative resources due to their high cost and environmental problems. Biomass waste has attracted much attention due to its carbon-rich structure and renewability, emerging as a potential raw material for graphene production to be used in sports equipment. However, further progress is required on the quality of graphene produced from waste biomass. This paper, therefore, summarizes the properties, structures, and production processes of graphene and its derivatives, as well as the inherent advantages of biomass waste-derived graphene. Finally, this paper reviews graphene's importance and application prospects in sports since this wonder material has made sports equipment available with high-strength and lightweight quality. Moreover, its outstanding thermal and electrical conductivity is exploited to prepare wearable sensors to collect more accurate sports data, thus helping to improve athletes' training levels and competitive performance. Although the large-scale production of biomass waste-derived graphene has yet to be realized, it is expected that its application will expand to various other fields due to the associated low cost and environmental friendliness of the preparation technique.

A Model of Collaboration Can Expand the Opportunities in Adaptive Sports Equipment.

ABSTRACT: Physical medicine and rehabilitation requires teamwork and innovation to help patients reach their goals and to optimize their quality of life, and one way is through participation in sports ( Sports Med Arthrosc Rev . 2019;27:73-82; PM R . 2015;7(10):1081-8; PM R . 2012;4(11):851-6; Phys Med Rehabil Clin N Am . 2019;30(1):289-99). Unfortunately, people with disabilities participate in sports ~20% less than their peers, and reasons for this disparity include equipment cost and availability ( Sports Med Arthrosc Rev . 2019;27:73-82; PM R . 2015;7(10):1081-8; Pediatrics . 2008;121(5):1057-61; Res Dev Disabil . 2017;67:9-18). A unique way for physical medicine and rehabilitation clinicians to aid in overcoming these barriers is to collaborate with other fields to make adaptive equipment that meets patients' needs.A multidisciplinary team including a physical medicine and rehabilitation resident physician and biomedical engineer, physical therapist, and machinist collaborated through a local nonprofit organization to design and build adaptive equipment solutions. This team designed two types of adaptive putters that are useable by golfers of various ages and functional ranges and a removable golf club grip for a player with limited grip strength.Implementation of a design team for creating adaptive equipment solutions is possible and can be done in the community setting or as part of a hospital system. In the authors' experience, taking a multidisciplinary team approach allowed developing more innovative and diverse solutions, and the athletes benefited by being able to participate in their desired sports activities.

A New Assessment of Bicycle Helmets: The Brain Injury Mitigation Effects of New Technologies in Oblique Impacts.

New helmet technologies have been developed to improve the mitigation of traumatic brain injury (TBI) in bicycle accidents. However, their effectiveness under oblique impacts, which produce more strains in the brain in comparison with vertical impacts adopted by helmet standards, is still unclear. Here we used a new method to assess the brain injury prevention effects of 27 bicycle helmets in oblique impacts, including helmets fitted with a friction-reducing layer (MIPS), a shearing pad (SPIN), a wavy cellular liner (WaveCel), an airbag helmet (Hövding) and a number of conventional helmets. We tested whether helmets fitted with the new technologies can provide better brain protection than conventional helmets. Each helmeted headform was dropped onto a 45° inclined anvil at 6.3 m/s at three locations, with each impact location producing a dominant head rotation about one anatomical axes of the head. A detailed computational model of TBI was used to determine strain distribution across the brain and in key anatomical regions, the corpus callosum and sulci. Our results show that, in comparison with conventional helmets, the majority of helmets incorporating new technologies significantly reduced peak rotational acceleration and velocity and maximal strain in corpus callosum and sulci. Only one helmet with MIPS significantly increased strain in the corpus collosum. The helmets fitted with MIPS and WaveCel were more effective in reducing strain in impacts producing sagittal rotations and a helmet fitted with SPIN in coronal rotations. The airbag helmet was effective in reducing brain strain in all impacts, however, peak rotational velocity and brain strain heavily depended on the analysis time. These results suggest that incorporating different impact locations in future oblique impact test methods and designing helmet technologies for the mitigation of head rotation in different planes are key to reducing brain injuries in bicycle accidents.

Breathing through a diving snorkel; theory and experiment of air flow resistance and cost of breathing.

The snorkel allows a surface swimmer to observe the underwater world through the face mask without being disturbed by inhaling. The effect of a snorkel on breathing resistance and cost is widely held to be substantial. This study aims to model these parameters and to measure indirectly the actual increases. Further, resistances of differing designs and dimensions were assessed and recommendations were made concerning use and choice. Maximal voluntary ventilation in 12 seconds (MVV12) was measured in 19 volunteers seated on dry land with and without a classic J-type snorkel (inner diameter 20.5 mm). The extra and total resistances and costs were calculated using the MVV12 data and using estimated airways resistance extrapolated from subject's demography and spirometric literature data. MVV12 measurements with snorkel showed a minute volume of 152 ±38 L∙min-1, 6.0 ±3.7% lower than without snorkel (p = 7.0x10-6). The theoretical MVV12, calculated from snorkel and airways resistances, decreased by 3.2%. Experimental total breathing resistance (457±83 Pa∙s∙L-1) was 6.5 ± 3.2% higher than without snorkel (p = 2.6x10-7), but the total mechanical breathing cost was unaffected by the snorkel (13.58 Watts with; 13.64 Watts without). Divers' estimations of resistance increase were exaggerated (8.8% at rest, 23% swimming). Classical J-type snorkels with an inner diameter ≥19.5 mm add 3-16% resistance . There is no risk of hypercapnia. Scuba divers are recommended to use their snorkel to breathe more comfortably on the surface. It is recommended the snorkel be made a mandatory safety accessory. The best multipurpose snorkel (19-21 mm) has no top appendages and no water release valve.

The use of outdoor gyms is associated with women and low-income people: a cross-sectional study.

OBJECTIVE: To examine the prevalence, and the demographic, socio-economic, and health correlates to Outdoor Gyms (OGs) use for adults from a southern Brazilian city. STUDY DESIGN: Population-based cross-sectional study. METHODS: A total of 431 adults (66.8% women) aged 18-87 years living in the surroundings of four OGs distributed in different regions of the city were randomly selected. Information about OG use for physical activity (PA) practice, and demographic, socio-economic, and health variables were collected by household interviews. Associations between independent variables and OG use were analyzed with results expressed as odds ratio (OR) and 95% confidence interval (95% CI). RESULTS: About one-third of participants (30.4%; 95% CI: 26.1-34.7) informed using OGs for PA practice, and 20.4% (95% CI 16.8-24.4) informed using it twice or more times a week (≥2x/week). Adjusted analysis indicated that the OG use ≥2x/week is higher for women (OR: 1.93; 95% CI: 1.11-3.35) and for those with lower family income (OR: 2.13; 95% CI: 1.03-4.13) than men and those with higher family income, respectively. CONCLUSION: About 30% of the population uses OGs for PA practice. Women and low-income people are those who more commonly use OGs for PA practice. The installation of these facilities in public spaces may reduce social inequities related to leisure-time PA.

Concurrent validity, inter-unit reliability and biological variability of a low-cost pocket radar for ball velocity measurement in soccer and tennis.

This study aimed to analyse the (i) concurrent validity, (ii) inter-unit reliability, and (iii) biological variability of a low-cost device called Pocket radar. Eleven men recreational soccer players performed 6 kicks to a soccer ball, whereas 13 men recreational tennis players conducted 10 shots to a tennis ball. All executions were simultaneously measured by two Pocket units and the Stalker radar (reference criterion). The within-subject variation among the executions was used for the biological variability analysis. The level of agreement and magnitude of errors included the intraclass correlation coefficient (ICC), Pearson's correlation coefficient (r), bias, and the smallest detectable change (SDC). A good agreement (ICC ≥ 0.98, r ≥ 0.98) and very low magnitude of error (SDC ≤ 7.70 km·h-1, bias ≤ 3.19 km·h-1) were found between both Pocket units and the Stalker, in soccer and tennis. Inter-unit analysis found limited technical errors (SDC ≤ 5.49 km·h-1, bias ≤ -0.93 km·h-1) and nearly perfect agreement (ICC = 0.99, r ≥ 0.98) in both sessions. These technical errors were lower than the variations due to the biological variability, in soccer (SDC = 2.47 km·h-1 vs. SDC ≥ 8.6 km·h-1) and tennis (SDC = 5.49 km·h-1 vs. SDC ≥ 21.95 km·h-1). These findings suggest the Pocket radar as a valid and highly sensitive tool for BV measurement.

Crank length alters kinematics and kinetics, yet not the economy of recumbent handcyclists at constant handgrip speeds.

Handcycling performance is dependent on the physiological economy of the athlete; however, handbike configuration and the biomechanical interaction between the two are also vital. The purpose of this study was to examine the effect of crank length manipulations on physiological and biomechanical aspects of recumbent handcycling performance in highly trained recumbent handcyclists at a constant linear handgrip speed and sport-specific intensity. Nine competitive handcyclists completed a 3-minute trial in an adjustable recumbent handbike in four crank length settings (150, 160, 170 & 180 mm) at 70% peak power output. Handgrip speed was controlled (1.6 m·s-1 ) across trials with cadences ranging from 102 to 85 rpm. Physiological economy, heart rate, and ratings of perceived exertion were monitored in all trials. Handcycling kinetics were quantified using an SRM (Schoberer Rad Messtechnik) powermeter, and upper limb kinematics were determined using a 10-camera VICON motion capture system. Physiological responses were not significantly affected by crank length. However, greater torque was generated (P < .0005) and peak torque occurred earlier during the push and pull phase (P ≤ .001) in longer cranks. Statistical parametric mapping revealed that the timing and orientation of shoulder flexion, shoulder abduction, and elbow extension were significantly altered in different crank lengths. Despite the biomechanical adaptations, these findings suggest that at constant handgrip speeds (and varying cadence) highly trained handcyclists may select crank lengths between 150 and 180 mm without affecting their physiological performance. Until further research, factors such as anthropometrics, comfort, and self-selected cadence should be used to facilitate crank length selection in recumbent handcyclists.

A comparison of economy between two different backpack designs for runners.

We compared two backpack designs (back/front or back only) in twelve recreational runners (age 22.0 ± 1.7years). An initial incremental exercise test (VO2max 52.2 ± 4.7 ml kg-1.min-1) was conducted, followed by four tests of 20 min duration (running speed 9.8 ± 1.1 km/h) with loads carried of 0, 1 kg, 3 kg, and 6 kg with the two backpack designs in a randomized order. Economy was assessed by energy cost of running (CR), oxygen cost (O2 cost), heart rate (HR) and rate of perceived exertion (RPE). Repeated measure ANOVA revealed a non-significant main effect for CR, O2 cost, HR, RPE between systems. Post-hoc comparison of significant time × position interaction showed for CR, F(3,33) = 5.34, p < .01, ηp2 = 0.33, and O2 cost, F(3,33) = 5.15, p < .01, ηp2 = 0.32, that carrying weight in the back/front were significantly lower after 20 min (CR: p = .02 and O2 cost: p = .03). These results suggest, that for longer runs the equal distribution of weight is advantageous.

The influence of pole lengths on O2-cost, kinematics, and performance in double poling at high speeds before and after a training period with long poles.

PURPOSE: Previous studies have found an acute performance improvement with longer pole lengths in double poling (DP) at low-to-moderate speeds. We investigated the influence of pole lengths (PL) on O2-cost, 3D kinematics, and performance in DP at moderate-to-high speeds before (Pre) and after (Post) eight training sessions with long poles on a rollerski treadmill. METHODS: Seven male and four female skiers completed tests with two different PLs (84 and 90% of body height). Submaximal O2-cost (1º; 4.5 [females] or 6 m s-1 [males]) and a peak velocity test (1º; ∼ 7.3 m s-1) were assessed before and after a six week training period. The training sessions consisted of 50 min of low-moderate intensity training and 4 × 10 s maximal sprints with PL90%. RESULTS: On average for all tests, PL84% induced 1.0 ± 1.0% higher peak velocity compared to PL90% (mean ± CI) with no difference in vertical displacement of center of mass (COMz). From Pre to Post, peak velocity and cycle time were increased and the displacement of COMz were reduced similarly for both PLs. At moderate speed, PL90% induced less displacement of COMz with subsequent 1.1 ± 0.7% lower O2-cost compared to PL84%. From Pre to Post, the O2-cost and COMz were reduced similarly for both PLs. CONCLUSIONS: Longer PL than skiers self-selected lengths reduce O2-cost at moderate speeds, but induced lower peak velocity. Eight sessions of training with PL90% did not influence the difference between PL84% and PL90% on O2-cost, kinematics or peak velocity.

Horizontal Crank Position Affects Economy and Upper Limb Kinematics of Recumbent Handcyclists.

PURPOSE: To determine the effects of horizontal crank position on economy and upper limb kinematics in recumbent handcycling. METHODS: Fifteen trained handcyclists performed trials at 50% and 70% of their peak aerobic power output (POPeak), determined during a maximal exercise test, in each horizontal crank position. Four horizontal crank positions, 94%, 97%, 100%, and 103% of arm length, were investigated. Horizontal crank positions were defined as the distance between the acromion angle to the center of the handgrip, while the crank arm was parallel to the floor and pointing away from the participant. Economy and upper limb kinematics were calculated during the final minute of each 3-min trial. RESULTS: Horizontal crank position significantly affected handcycling economy at 70% POPeak (P < 0.01) but not at 50% POPeak (P = 0.44). The 97% horizontal crank position (16.0 [1.5] mL·min·W) was significantly more economical than the 94% (16.7 (1.9) mL·min·W) (P = 0.04) and 103% (16.6 (1.7) mL·min·W) (P < 0.01) positions. The 100% horizontal crank position (16.2 (1.7) mL·min·W) was significantly more economical than the 103% position (P < 0.01). Statistical parametric mapping indicated that an increase in horizontal crank position, from 94% to 103%, caused a significant increase in elbow extension, shoulder flexion, adduction, internal rotation, scapular internal rotation, wrist flexion, clavicle depression and clavicle protraction between 0% and 50% (0°-180°) of the cycle (P < 0.05). CONCLUSIONS: Positioning the cranks at 97% to 100% of the athletes' arm length improved handcycling economy at 70% POPeak as, potentially, the musculature surrounding the joints of the upper limb were in a more favorable position to produce force economically.

Effects of a long-term home-based exercise training programme using minimal equipment vs. usual care in COPD patients: a study protocol for two multicentre randomised controlled trials (HOMEX-1 and HOMEX-2 trials).

BACKGROUND: Exercise training is an important component of pulmonary rehabilitation (PR) programmes in chronic obstructive pulmonary disease (COPD), but the great majority of COPD patients who would benefit from PR never follow such programmes or fail to maintain exercise training after PR completion. Against this background, we developed an exercise training programme that requires minimal equipment and can be implemented long-term in the patient's home-setting. The aims of the HOMEX-1 and HOMEX-2 trials are to assess the effectiveness of this home-based exercise training programme in two groups of COPD patients over the course of one year: patients who have completed PR (HOMEX-1 trial) and patients who did not enrol in existing PR programmes within the last two years (HOMEX-2 trial). METHODS: HOMEX-1 and HOMEX-2 are multicentre, parallel group, randomised controlled trials. For both trials each, it is planned to include 120 study participants with a diagnosis of COPD. Participants will be randomised with a 1:1 ratio into the intervention group or the control group (usual care/no intervention). The intervention consists of minimal-equipment exercise training elements with progressive level of intensity, conducted by the participant during six days per week and instructed and coached by a trained health care professional during three home visits and regular telephone calls during one year. Primary outcome is change in dyspnoea (domain of Chronic Respiratory Questionnaire) from baseline to 12-months follow-up. Secondary outcomes are change in dyspnoea over the course of the year (assessed at 3, 6 and 12 month) and change in functional exercise capacity, physical activity, health-related quality of life, health status, exacerbations and symptoms from baseline to 12 months follow-up. In addition, explanatory, safety and cost-effectiveness outcomes will be assessed. We will conduct intention-to-treat analyses separately per trial and per protocol analyses as sensitivity analyses. DISCUSSION: The HOMEX-1 and HOMEX-2 trials assess a novel intervention that provides an innovative way of making exercise training as accessible as possible for COPD patients. If the intervention proves to be effective long-term, it will fill the gap of providing an easily accessible and feasible intervention so that more COPD patients can follow an exercise programme. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: HOMEX-1 NCT03461887 (registration date: March 12, 2018; retrospectively registered); HOMEX-2 NCT03654092 (registration date: August 31, 2018).

A Randomized Crossover Study Investigating the Running Economy of Highly-Trained Male and Female Distance Runners in Marathon Racing Shoes versus Track Spikes.

BACKGROUND: Running economy represents a complex interplay of physiological and biomechanical factors that are able to adapt chronically through training, or acutely through other interventions such as changes in footwear. The Nike Vaporfly (NVF) shoe was designed for marathon running on the roads and has been shown to improve running economy by ~ 4% compared with other marathon shoes, however, during track racing, distance runners traditionally wear a much lighter shoe with an embedded spike plate around the forefoot. OBJECTIVE: The aim of this study was to determine if, and to what extent, the NVF shoes improve running economy compared with established track spikes (Nike Zoom Matumbo 3 [NZM]) and marathon racing shoes (Adidas Adizero Adios 3 [ADI]). METHODS: Twenty-four highly-trained runners (12 male, 12 female) ran 4 × 5 min trials on a treadmill while wearing each of the four shoe conditions: NVF, NZM, ADI, and the NVF matched in weight to the ADI shoe (NVF +), during three separate visits-visit 1: familiarization; visit 2: 14 and 18 km·h-1 for men, 14 and 16 km·h-1 for women; visit 3: 16 km·h-1 for men, 15 km·h-1 for women, plus a maximal rate of oxygen uptake (VO2max) test for both sexes. We measured the rates of oxygen uptake (VO2), carbon dioxide production and biomechanical measures while running at each velocity and shoe condition. RESULTS: The NVF shoe improved running economy by 2.6 ± 1.3% compared with the NZM, 4.2 ± 1.2% compared with ADI, and 2.9 ± 1.3% when matched in weight of the ADI shoe. Among the 24 subjects, the difference in running economy over the four velocities between the NVF and NZM shoes ranged from + 0.50 to - 5.34%, and - 1.72 to - 7.15% for NVF versus ADI. Correlations between changes in running economy and changes in biomechanical variables were either trivial or small, but unclear. CONCLUSION: The NVF enhanced running economy compared with track spikes and marathon shoes, and should be considered a viable shoe option for track and road racing.

Laboratory Evaluation of Low-Cost Wearable Sensors for Measuring Head Impacts in Sports.

Advances in low-cost wearable head impact sensor technology provide potential benefits regarding sports safety for both consumers and researchers. However, previous laboratory evaluations are not directly comparable and do not incorporate test conditions representative of unhelmeted impacts. This study addresses those limitations. The xPatch by X2 Biosystems and the SIM-G by Triax Technologies were placed on a National Operating Committee on Standards for Athletic Equipment (NOCSAE) headform with a Hybrid III neck which underwent impact tests using a pendulum. Impact conditions included helmeted, padded impactor to bare head, and rigid impactor to bare head to represent long- and short-duration impacts seen in helmeted and unhelmeted sports. The wearable sensors were evaluated on their kinematic accuracy by comparing results to reference sensors located at the headform center of gravity. Statistical tests for equivalence were performed on the slope of the linear regression between wearable sensors and reference. The xPatch gave equivalent measurements to the reference in select longer-duration impacts, whereas the SIM-G had large variance leading to no equivalence. For the short-duration impacts, both wearable sensors underpredicted the reference. This error can be improved with increases in sampling rate from 1 to 1.5 kHz. Follow-up evaluations should be performed on the field to identify error in vivo.

Kicking Performance in Young U9 to U20 Soccer Players: Assessment of Velocity and Accuracy Simultaneously.

PURPOSE: The purpose of this study was to compare the kicking performance of young soccer players in the U9 to U20 age groups. METHOD: Three hundred and sixty-six Brazilian players were evaluated on an official pitch using three-dimensional kinematics to measure (300 Hz) ball velocity (Vball), foot velocity (Vfoot), Vball/Vfoot ratio, last stride length, and distance between the support foot and the ball. Simultaneously, a two-dimensional procedure was also conducted to compute (60 Hz) the mean radial error, bivariate variable error, and accuracy. Possible age-related differences were assessed through one-way analysis of variance and magnitude-based inferences. RESULTS: Ball velocity increased by 103% (p < .001, η2 = .39) from the U11 age group (48.54 ± 8.31 km/hr) to the U20 age group (98.74 ± 16.35 km/hr). Foot velocity presented a 59% increase (p < .001, η2 = .32) from the U11 age group (49.08 ± 5.16 km/hr) to U20 (78.24 ± 9.49 km/hr). This finding was due to improvement in the quality of foot-ball impact (Vball/Vfoot ratio) from U11 (0.99 ± 0.13 a.u.) to U20 (1.26 ± 0.11 a.u.; p < .001, η2 = .25). Parameters such as mean radial error and accuracy appeared to be impaired during the growth spurt (U13-U15). Last stride length was correlated, low to moderately high, with Vball in all age groups (r = .36-.79). CONCLUSIONS: In summary, we concluded that simple biomechanical parameters of kicking performance presented distinct development. These results suggest that different training strategies specific for each age group could be applied. We provide predictive equations to aid coaches in the long-term monitoring process to develop the kick in soccer or search for talented young players.

Pole lengths influence O2-cost during double poling in highly trained cross-country skiers.

PURPOSE: In elite cross-country skiing, double poling is used in different terrain. This study compared O2-cost and kinematics during double poling with four different pole lengths [self-selected (SS), SS - 5 cm, SS + 5 cm, SS + 10 cm] at Low versus Moderate incline. METHODS: Thirteen highly trained male cross-country skiers (mean ± SD 23 ± 3 years; 182 ± 4 cm; 77 ± 6 kg) completed eight submaximal trials with roller skis on a treadmill at two conditions: "Low incline" (1.7°; 4.5 m s-1) and "Moderate incline" (4.5°; 2.5 m s-1) with each of the four pole lengths. O2-cost and 3D body kinematics were assessed in each trial. RESULTS: In Low incline, SS + 10 cm induced a lower O2-cost than all the other pole lengths [P < 0.05; effect size (ES) 0.5-0.8], whereas no differences were found between the remaining pole lengths (P > 0.05; ES 0.2-0.4). In Moderate incline, significant differences between all pole lengths were found for O2-cost, with SS - 5 cm > SS > SS + 5 cm > SS + 10 cm (P < 0.05; ES 0.6-1.8). The relative differences in O2-cost between SS and the other pole lengths were greater in Moderate incline than Low incline (SS - 5 cm; 1.5%, ES 0.8, SS + 5 cm; 1.3%, ES 1.0, and SS + 10 cm; 1.9%, ES 1.0, all P < 0.05). No difference was found in cycle, poling or reposition times between pole lengths. However, at both conditions a smaller total vertical displacement of center of mass was observed with SS + 10 cm compared to the other pole lengths. CONCLUSION: Increasing pole length from SS - 5 cm to SS + 10 cm during double poling induced lower O2-cost and this advantage was greater in Moderate compared to Low incline.

Distribución de los escenarios deportivos en la ciudad de Medellín: condiciones de posibilidad para su acceso para la mejora de la cualidad de vida de los ciudadanos / Distribuição de instalações esportivas na cidade de Medellín: condições de possibilidade de contribuir para a melhoria da qualidade de vida dos cidadãos / Distribution of sports scenarios in the city of Medellín: conditions of possibility for accessing them in order to improve citizens' life quality

Se presentan los resultados de la aplicación del Índice de desarrollo y acceso deportivo (IDAD), realizado como componente de la investigación Los escenarios deportivos y las Unidades de Vida Articulada (UVA) en la dinámica activa de la ciudad, que buscó establecer la relación entre estos y objetivos sociales. Se trabajó con una perspectiva cuanti-cualitativa, con el IDAD, conversaciones, talleres, formatos y socializaciones. El texto se ocupa del IDAD. La investigación logró evidenciar la importancia de la relación entre acceso y distribución para la equidad, como uno los principales asuntos problemáticos en relación con objetivos de tipo social y contribuyó con propuestas y posibles rutas para el fortalecimiento de la política pública del sector en la ciudad, desde los escenarios deportivos como condición de posibilidad(AU)

Este artigo apresenta os resultados da implementação do Índice de Desenvolvimento e Acesso Desportivo (IDAD), realizados como um componente da investigação "Os recintos esportivos e Unidades de Vida Articulada" (UVA) na dinâmica ativa da cidade, que procura estabelecer a relação entre esses e os fins sociais. Trabalhamos com uma perspectiva quanti-qualitativa com o IDAD, palestras, workshops, formatos e socializações. Este artigo trata do IDAD. Nesse contexto, a pesquisa conseguiu evidenciar a importância da relação para acesso e distribuição como um dos principais problemas relacionados aos objetivos sociais e contribuiu com propostas e possíveis caminhos para fortalecer as políticas públicas do setor na cidade, a partir dos espaços desportivos como condição de possibilidade(AU)

The article presents the results of the application of the Development Index and Sports Access (IDAD) under the study Sports Scenarios and the Articulated Life Unit (UVA) in the city's active dynamics, which sought to establish the relationship between these and social objectives. We worked under a quantitative-qualitative perspective, using the IDAD, conversations, workshops, formats, and socializations. The present text addresses the IDAD. In this context, the research was able to highlight the importance of the relationship between access and distribution for equity as one of the main problems related to social objectives and contributed with proposals and possible routes for strengthening the sector's public policy in the city based on sports scenarios as a condition of possibility(AU)

The Influence of Pole Length on Performance, O2 Cost, and Kinematics in Double Poling.

PURPOSE: In the double-poling (DP) cross-country-skiing technique, propulsive forces are transferred solely through the poles. The aim of the current study was to investigate how pole length influences DP performance, O2 cost, and kinematics during treadmill roller skiing. METHODS: Nine male competitive cross-country skiers (24 ± 3 y, 180 ± 5 cm, 72 ± 5 kg, VO2max running 76 ± 6 mL · kg-1 · min-1) completed 2 identical test protocols using self-selected (84% ± 1% of body height) and long poles (self-selected + 7.5 cm; 88% ± 1% of body height) in a counterbalanced fashion. Each test protocol included a 5-min warm-up (2.5 m/s; 2.5°) and three 5-min submaximal sessions (3.0, 3.5, and 4.0 m/s; 2.5°) for assessment of O2 cost, followed by a selfpaced 1000-m time trial (~3 min, >5.0 m/s; 2.5°). Temporal patterns and kinematics were assessed using accelerometers and 2D video. RESULTS: Long poles reduced 1000-m time (mean ± 90% confidence interval; -1.0% ± 0.7%, P = .054) and submaximal O2 cost (-2.7% ± 1.0%, P = .002) compared with self-selected poles. The center-of-mass (CoM) vertical range of displacement tended to be smaller for long than for self-selected poles (23.3 ± 3.0 vs 24.3 ± 3.0 cm, P = .07). Cycle and reposition time did not differ between pole lengths at any speeds tested, whereas poling time tended to be shorter for self-selected than for long poles at the lower speeds (≤3.5 m/s, P ≤ .10) but not at the higher speeds (≥4.0 m/s, P ≥ .23). CONCLUSIONS: DP 1000-m time, submaximal O2 cost, and CoM vertical range of displacement were reduced in competitive cross-country skiers using poles 7.5 cm longer than self-selected ones.

Historical Improvement in Speed Skating Economy.

Half the improvement in 1500-m speed-skating world records can be explained by technological innovations and the other half by athletic improvement. It is hypothesized that improved skating economy is accountable for much of the athletic improvement. PURPOSE: To determine skating economy in contemporary athletes and to evaluate the change in economy over the years. METHODS: Contemporary skaters of the Dutch national junior team (n = 8) skated 3 bouts of 6 laps at submaximal velocity, from which skating economy was calculated (in mL O2 ・ kg-1 ・ km-1). A literature search provided historic data on skating velocity and submaximal V̇O2 (in mL ・ kg-1 ・ min-1), from which skating economy was determined. The association between year and skating economy was determined using linear-regression analysis. Correcting the change in economy for technological innovations resulted in an estimate of the association between year and economy due to athletic improvement. RESULTS: A mean (± SD) skating economy of 73.4 ± 6.4 mL O2 ・ kg-1 ・ km-1 was found in contemporary athletes. Skating economy improved significantly over the historical time frame (-0.57 mL O2 ・ kg-1 ・ km-1 ・ y-1, 95% confidence interval [-0.84, -0.31]). In the final regression model for the klapskate era, with altitude as confounder, skating economy improved with a nonsignificant -0.58 mL O2 ・ kg-1 ・ km-1 ・ y-1 ([-1.19, 0.035]). CONCLUSIONS: Skating economy was 73.4 ± 6.4 mL O2 ・ kg-1 ・ km-1 in contemporary athletes and improved over the past ~50 y. The association between year and skating economy due to athletic improvement, for the klapskate era, approached significance, suggesting a possible improvement in economy over these years.

Metabolic cost of running is greater on a treadmill with a stiffer running platform.

Exercise testing on motorised treadmills provides valuable information about running performance and metabolism; however, the impact of treadmill type on these tests has not been investigated. This study compared the energy demand of running on two laboratory treadmills: an HP Cosmos (C) and a Quinton (Q) model, with the latter having a 4.5 times stiffer running platform. Twelve experienced runners ran identical bouts on these treadmills at a range of four submaximal velocities (reported data is for the velocity that approximated 75-81% VO2max). The stiffer treadmill elicited higher oxygen consumption (C: 46.7 ± 3.8; Q: 50.1 ± 4.3 ml·kg-1 · min-1), energy expenditure (C: 16.0 ± 2.5; Q: 17.7 ± 2.9 kcal · min-1), carbohydrate oxidation (C: 9.6 ± 3.1; Q: 13.0 ± 3.9 kcal · min-1), heart rate (C: 155 ± 16; Q: 163 ± 16 beats · min-1) and rating of perceived exertion (C: 13.8 ± 1.2; Q: 14.7 ± 1.2), but lower fat oxidation (C: 6.4 ± 2.3; Q: 4.6 ± 2.5 kcal · min-1) (all analysis of variance treadmill comparisons P < 0.01). This study confirms that caution is required when comparing performance and metabolic results between different treadmills and suggests that treadmills will vary in their comparability to over-ground running depending on the running platform stiffness.

Increasing surfboard volume reduces energy expenditure during paddling.

The purpose of this study was to investigate how altering surfboard volume (BV) affects energy expenditure during paddling. Twenty surfers paddled in a swim flume on five surfboards in random order twice. All surfboards varied only in thickness and ranged in BV from 28.4 to 37.4 L. Measurements of heart rate (HR), oxygen consumption (VO2), pitch angle, roll angle and paddling cadence were measured. VO2 and HR significantly decreased on thicker boards [VO2: r = -0.984, p = 0.003; HR: r = -0.972, p = 0.006]. There was also a significant decrease in pitch and roll angles on thicker boards [Pitch: r = -0.995, p < 0.001; Roll: r = -0.911, p = 0.031]. Results from this study suggest that increasing BV reduces the metabolic cost of paddling as a result of lower pitch and roll angles, thus providing mechanical evidence for increased paddling efficiency on surfboards with more volume. Practioner Summary: This study investigated the impact of surfboard volume on energy expenditure during paddling. Results from this study suggest that increasing surfboard volume reduces the metabolic cost of paddling as a result of lower pitch and roll angles, thus providing mechanical evidence for increased paddling efficiency on surfboards with more volume.