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1.
Nat Commun ; 11(1): 4356, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32868777

RESUMO

Complex motor commands for human locomotion are generated through the combination of motor modules representable as muscle synergies. Recent data have argued that muscle synergies are inborn or determined early in life, but development of the neuro-musculoskeletal system and acquisition of new skills may demand fine-tuning or reshaping of the early synergies. We seek to understand how locomotor synergies change during development and training by studying the synergies for running in preschoolers and diverse adults from sedentary subjects to elite marathoners, totaling 63 subjects assessed over 100 sessions. During development, synergies are fractionated into units with fewer muscles. As adults train to run, specific synergies coalesce to become merged synergies. Presences of specific synergy-merging patterns correlate with enhanced or reduced running efficiency. Fractionation and merging of muscle synergies may be a mechanism for modifying early motor modules (Nature) to accommodate the changing limb biomechanics and influences from sensorimotor training (Nurture).


Assuntos
Músculo Esquelético/fisiologia , Corrida/fisiologia , Adulto , Fenômenos Biomecânicos , Criança , Pré-Escolar , Eletromiografia , Feminino , Humanos , Locomoção , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/crescimento & desenvolvimento
2.
PLoS One ; 15(7): e0236047, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32673375

RESUMO

Providing runners with footwear that match their functional needs has the potential to improve footwear comfort, enhance running performance and reduce the risk of overuse injuries. It is currently not known how footwear experts make decisions about different shoe features and their properties for runners of different levels. We performed a Delphi study in order to understand: 1) definitions of different runner levels, 2) which footwear features are considered important and 3) how these features should be prescribed for runners of different levels. Experienced academics, journalists, coaches, bloggers and physicians that examine the effects of footwear on running were recruited to participate in three rounds of a Delphi study. Three runner level definitions were refined throughout this study based on expert feedback. Experts were also provided a list of 20 different footwear features. They were asked which features were important and what the properties of those features should be. Twenty-four experts, most with 10+ years of experience, completed all three rounds of this study. These experts came to a consensus for the characteristics of three different running levels. They indicated that 12 of the 20 footwear features initially proposed were important for footwear design. Of these 12 features, experts came to a consensus on how to apply five footwear feature properties for all three different running levels. These features were: upper breathability, forefoot bending stiffness, heel-to-toe drop, torsional bending stiffness and crash pad. Interestingly, the experts were not able to come to a consensus on one of the most researched footwear features, rearfoot midsole hardness. These recommendations can provide a starting point for further biomechanical studies, especially for features that are considered as important, but have not yet been examined experimentally.


Assuntos
Técnica Delfos , Corrida/fisiologia , Sapatos , Adulto , Desempenho Atlético , Consenso , Feminino , Humanos , Masculino , Recreação , Inquéritos e Questionários
3.
PLoS One ; 15(7): e0236024, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32687507

RESUMO

Training prescription and monitoring of team-sport athletes rely on accurate quantification of player movement. Our aim was to determine the sensitivity, reliability and construct validity of measures derived from a wearable device incorporating Global Positioning System (GPS) and accelerometer technology to quantify the peak periods of rugby competition. Match movement data were collected from 30 elite and 30 sub-elite rugby union players across respective competitive seasons. Accelerometer and GPS measures were analysed using a rolling average to identify peak movement for epochs ranging from 5 to 600 seconds. General linear mixed modelling was used to quantify the effects of playing position and match-half on the peak movement and variabilities within and between players represented reliability of each measure. Mean positional differences and match-half changes were assessed via standardisation and magnitude-based decisions. Sensitivity of measures was quantified via evaluation of ("signal") and typical error of measurement ("noise"). GPS and accelerometer measures had poor sensitivity for quantifying peak movement across all epochs and both levels of rugby union competition (noise 4× to 5× the signal). All measures displayed correspondingly low reliability across most epochs and both levels of competition (ICC<0.50). Construct validity was evident in mean differences between playing positions and match halves that were consistent with expected activity profiles in rugby union. However, it was clear from the pattern of differences across epoch durations and levels of competition that GPS and accelerometer measures provided different information about player movement. The poor sensitivity and low reliability of GPS and accelerometer measures of peak movement imply that rugby union players need to be monitored across many matches to obtain adequate precision for assessing individuals. Although all measures displayed construct validity, accelerometers provided meaningful information additional to that of GPS. We recommend using accelerometers alongside GPS to monitor and prescribe match respresentative training.


Assuntos
Acelerometria/métodos , Atletas/estatística & dados numéricos , Desempenho Atlético/fisiologia , Futebol Americano/fisiologia , Sistemas de Informação Geográfica/instrumentação , Corrida/fisiologia , Análise e Desempenho de Tarefas , Adulto , Humanos , Masculino , Curva ROC , Reprodutibilidade dos Testes
5.
Int J Sports Physiol Perform ; 15(5): 696-704, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32698124

RESUMO

PURPOSE: To investigate within-player effect, between-player effect, and individual response of external training load from player tracking devices on session rating of perceived exertion training load (sRPE-TL) in elite football players. METHODS: The authors collected sRPE-TL from 18 outfield players in 21 training sessions. Total distance, high-speed running distance (>14.4 m/s), very high-speed running distance (>19.8 m/s), PlayerLoad™, PlayerLoad2D™, and high-intensity events (HIE > 1.5, HIE > 2.5, and HIE > 3.5 m/s) were extracted from the tracking devices. The authors modeled within-player and between-player effects of single external load variables on sRPE-TL, and multiple levels of variability, using a linear mixed model. The effect of 2 SDs of external load on sRPE-TL was evaluated with magnitude-based inferences. RESULTS: Total distance, PlayerLoad™, PlayerLoad2D™, and HIE > 1.5 had most likely substantial within-player effects on sRPE-TL (100%-106%, very large effect sizes). Moreover, the authors observed likely substantial between-player effects (12%-19%, small to moderate effect sizes) from the majority of the external load variables and likely to very likely substantial individual responses of PlayerLoad™, high-speed running distance, very high-speed running distance, and HIE > 1.5 (19%-30% coefficient of variation, moderate to large effect sizes). Finally, sRPE-TL showed large to very large between-session variability with all external load variables. CONCLUSIONS: External load variables with low intensity-thresholds had the strongest relationship with sRPE-TL. Furthermore, the between-player effect of external load and the individual response to external load advocate for monitoring sRPE-TL in addition to external load. Finally, the large between-session variability in sRPE-TL demonstrates that substantial amounts of sRPE-TL in training sessions are not explained by single external load variables.


Assuntos
Percepção/fisiologia , Condicionamento Físico Humano/métodos , Esforço Físico/fisiologia , Futebol/fisiologia , Adulto , Comportamento Competitivo/fisiologia , Monitores de Aptidão Física , Humanos , Masculino , Corrida/fisiologia
6.
Medicine (Baltimore) ; 99(27): e20943, 2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-32629698

RESUMO

Angiotensin II mediates exercise-induced hypertension (EIH), which adversely impacts future cardiovascular health. There is paucity of data on the association between EIH and angiotensin II in well-trained middle-aged marathoners. Therefore, we investigated the renin-angiotensin-aldosterone-system and total nitric oxide activity in middle-aged marathoners with EIH.Seventy middle-aged marathoners were divided into 3 groups: normal blood pressure ([NBPG] [n = 21]), EIH group ([EIHG] [n = 35]), and complex hypertension group ([CHG] [n = 14]). We defined NBPG as resting systolic BP/diastolic BP (SBP/DBP) of ≤140/90 mm Hg and maximal exercise SBP of ≤210 mm Hg, EIHG as resting SBP/DBP ≤140/90 mm Hg and maximal exercise SBP of ≥210 mm Hg, and CHG as resting SBP/DBP ≥140/90 mm Hg and maximal exercise SBP of ≥210 mm Hg. Renin-angiotensin-aldosterone-system and NO levels were measured before and 30 minutes after the graded exercise test.Renin level was elevated while angiotensin level was reduced after 30 minutes of graded exercise test. There was no change in angiotensin I and angiotensin converting enzyme levels. Comparing the groups, renin level was only elevated in the CHG during recovery, while aldosterone level was higher than the baseline level in the recovery phase in all groups. Angiotensin I level remained unchanged in all groups. Angiotensin II level reduced significantly in the NBPG group but remained at the baseline in the EIHG and CHG groups. NO level was unchanged in the NBPG group but reduced in the EIHG and CHG groups after exercise. At 3 minutes of recovery, SBP was the highest in the NBPG group, followed by the EIHG and CHG groups (P < .05).In conclusion, angiotensin II activity and reduced NO level are associated with EIH in middle-aged long-distance runners. Angiotensin II inhibitors may; therefore, be the more appropriate antihypertensive medication for runners with EIH.


Assuntos
Angiotensina II/sangue , Exercício Físico , Hipertensão/fisiopatologia , Óxido Nítrico/sangue , Corrida , Adulto , Pressão Sanguínea , Humanos , Hipertensão/sangue , Masculino , Pessoa de Meia-Idade , Sistema Renina-Angiotensina
7.
PLoS One ; 15(6): e0234458, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32569264

RESUMO

We investigated the association of multiple single nucleotide polymorphisms (SNPs) with athlete status and power/speed performance in elite male youth soccer players (ESP) and control participants (CON) at different stages of maturity. ESP (n = 535; aged 8-23 years) and CON (n = 151; aged 9-26 years) were genotyped for 10 SNPs and grouped according to years from predicted peak-height-velocity (PHV), i.e. pre- or post-PHV, to determine maturity status. Participants performed bilateral vertical countermovement jumps, bilateral horizontal-forward countermovement jumps, 20m sprints and modified 505-agility tests. Compared to CON, pre-PHV ESP demonstrated a higher ACTN3 (rs1815739) XX ('endurance') genotype frequency distribution, while post-PHV ESP revealed a higher frequency distribution of the PPARA (rs4253778) C-allele, AGT (rs699) GG genotype and NOS3 (rs2070744) T-allele ('power' genotypes/alleles). BDNF (rs6265) CC, COL5A1 (rs12722) CC and NOS3 TT homozygotes sprinted quicker than A-allele carriers, CT heterozygotes and CC homozygotes, respectively. COL2A1 (rs2070739) CC and AMPD1 (rs17602729) GG homozygotes sprinted faster than their respective minor allele carrier counterparts in CON and pre-PHV ESP, respectively. BDNF CC homozygotes jumped further than T-allele carriers, while ESP COL5A1 CC homozygotes jumped higher than TT homozygotes. To conclude, we have shown for the first time that pre- and post-PHV ESP have distinct genetic profiles, with pre-PHV ESP more suited for endurance, and post-PHV ESP for power and speed (the latter phenotypes being crucial attributes for post-PHV ESP). We have also demonstrated that power, acceleration and sprint performance were associated with five SNPs, both individually and in combination, possibly by influencing muscle size and neuromuscular activation.


Assuntos
Atletas , Desempenho Atlético/fisiologia , Perfil Genético , Maturidade Sexual/fisiologia , Futebol , Aceleração , Actinina/genética , Adolescente , Estudos de Casos e Controles , Criança , Colágeno Tipo II/genética , Colágeno Tipo V/genética , Frequência do Gene , Humanos , Masculino , Força Muscular/genética , Polimorfismo de Nucleotídeo Único , Corrida/fisiologia , Adulto Jovem
9.
PLoS One ; 15(6): e0233266, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492034

RESUMO

For gait classification, hoof-on and hoof-off events are fundamental locomotion characteristics of interest. These events can be measured with inertial measurement units (IMUs) which measure the acceleration and angular velocity in three directions. The aim of this study was to present two algorithms for automatic detection of hoof-events from the acceleration and angular velocity signals measured by hoof-mounted IMUs in walk and trot on a hard surface. Seven Warmblood horses were equipped with two wireless IMUs, which were attached to the lateral wall of the right front (RF) and hind (RH) hooves. Horses were walked and trotted on a lead over a force plate for internal validation. The agreement between the algorithms for the acceleration and angular velocity signals with the force plate was evaluated by Bland Altman analysis and linear mixed model analysis. These analyses were performed for both hoof-on and hoof-off detection and for both algorithms separately. For the hoof-on detection, the angular velocity algorithm was the most accurate with an accuracy between 2.39 and 12.22 ms and a precision of around 13.80 ms, depending on gait and hoof. For hoof-off detection, the acceleration algorithm was the most accurate with an accuracy of 3.20 ms and precision of 6.39 ms, independent of gait and hoof. These algorithms look highly promising for gait classification purposes although the applicability of these algorithms should be investigated under different circumstances, such as different surfaces and different hoof trimming conditions.


Assuntos
Algoritmos , Análise da Marcha/veterinária , Marcha/fisiologia , Cavalos/fisiologia , Aceleração , Animais , Fenômenos Biomecânicos , Feminino , Membro Anterior/fisiologia , Análise da Marcha/instrumentação , Análise da Marcha/estatística & dados numéricos , Membro Posterior/fisiologia , Casco e Garras/fisiologia , Modelos Lineares , Masculino , Tecnologia de Sensoriamento Remoto/instrumentação , Tecnologia de Sensoriamento Remoto/estatística & dados numéricos , Tecnologia de Sensoriamento Remoto/veterinária , Corrida/fisiologia , Caminhada/fisiologia , Tecnologia sem Fio/instrumentação , Tecnologia sem Fio/estatística & dados numéricos
10.
J Sports Sci ; 38(16): 1877-1885, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32508286

RESUMO

With potential implications for recovery and conditioning practices, the aim of this study was to assess the cumulative and residual response of angle specific eccentric knee flexor (eccKF) strength indices following soccer-specific activity. Thirteen semi-professional soccer players were therefore required to complete a 90-minute soccer-specific treadmill running. with eccKF isokinetic strength assessments completed pre-trial, immediately post-trial, and 48 hours post-trial. The strength assessments comprised the completion of 5 repetitions at angular velocities of 60 and 300 deg·s-1. Isokinetic data was analysed for measures of peak torque (PT), angle of peak torque (APT), functional range (FR), and angle specific torque (AST). Significant post-trial impairments were observed for measures of slow velocity PT60 (6.6%) and AST300 (12.5%). Further significant differences were observed 48 hours post-trial for PT300 (10.7%) and PT60 (12.8%) PT, APT60 (~15°), and AST300 (>13.6%). These data have implications for post exercise recovery monitoring and the prescription of recovery modalities and conditioning practices in the 2 days following match-play. The AST and APT responses highlight the importance of analysis of the entire strength-angle curve and at a range of angular velocities.


Assuntos
Joelho/fisiologia , Força Muscular/fisiologia , Corrida/fisiologia , Futebol/fisiologia , Adulto , Humanos , Masculino , Fadiga Muscular/fisiologia , Dinamômetro de Força Muscular , Músculo Esquelético/fisiologia , Fatores de Tempo , Torque , Adulto Jovem
11.
Sports Health ; 12(4): 334-340, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525466

RESUMO

BACKGROUND: Female runners are at increased risk of stress fractures (SFs) compared with men. Literature is lacking with regard to best practice for preventing and treating SFs in women. The purpose of the study was to compare physiological measures and running-related factors between women of various ages and running abilities with and without a history of running-related SFs. HYPOTHESIS: Women with and without SF histories will differ with regard to medical and menstrual history, bone health, body composition, nutrition, and running history. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 20 female runners with SF histories were matched based on age and running distance with 20 women without SF histories. Data included medical, menstrual, running, injury, and nutritional histories; blood histology related to nutritional, hormonal, and bone-related risk factors; and bone density, fat, and lean tissue using dual energy x-ray absorptiometry. Paired t tests were used to examine differences between women with and without SF histories, and Spearmen correlations were conducted to examine relationships between physiological factors. RESULTS: Women with SF histories had lower hip bone mineral density compared with women without SF histories (P < 0.05). SF history was moderately correlated with menstrual changes during increased training times (r = 0.580; P < 0.0001) but was not correlated with any other physiological factor. There was a moderate correlation within the SF group (r = 0.65; P = 0.004) for bone markers for resorption and formation both increasing, indicating increased bone turnover. CONCLUSION: Female runners with low hip bone mineral density, menstrual changes during peak training, and elevated bone turnover markers may be at increased risk of SF. CLINICAL RELEVANCE: Female runners need routine screening for risks associated with SF occurrence. As bone mineral density and bone turnover markers are not routinely assessed in this population, important risk factors may be missed.


Assuntos
Fraturas de Estresse/fisiopatologia , Corrida/fisiologia , Adulto , Biomarcadores/sangue , Distribuição da Gordura Corporal , Índice de Massa Corporal , Densidade Óssea/fisiologia , Remodelação Óssea/fisiologia , Feminino , Humanos , Menstruação , Pessoa de Meia-Idade , Condicionamento Físico Humano/fisiologia , Projetos Piloto , Estudos Prospectivos , Fatores de Risco , Fenômenos Fisiológicos da Nutrição Esportiva , Adulto Jovem
12.
PLoS One ; 15(6): e0234401, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32584826

RESUMO

Previous studies suggest that marathon running induces lower extremity muscle damage. This study aimed to examine inter- and intramuscular differences in hamstring muscle damage after a marathon using transverse relaxation time (T2)-weighted magnetic resonance images (MRI). 20 healthy collegiate marathon runners (15 males) were recruited for this study. T2-MRI was performed before (PRE) and at 1 (D1), 3 (D3), and 8 days (D8) after marathon, and the T2 values of each hamstring muscle at the distal, middle, and proximal sites were calculated. Results indicated that no significant intermuscular differences in T2 changes were observed and that, regardless of muscle, the T2 values of the distal and middle sites increased significantly at D1 and D3 and recovered at D8, although those values of the proximal site remained constant. T2 significantly increased at distal and middle sites of the biceps femoris long head on D1 (p = 0.030 and p = 0.004, respectively) and D3 (p = 0.007 and p = 0.041, respectively), distal biceps femoris short head on D1 (p = 0.036), distal semitendinosus on D1 (p = 0.047) and D3 (p = 0.010), middle semitendinosus on D1 (p = 0.005), and distal and middle sites of the semimembranosus on D1 (p = 0.008 and p = 0.040, respectively) and D3 (p = 0.002 and p = 0.018, respectively). These results suggest that the distal and middle sites of the hamstring muscles are more susceptible to damage induced by running a full marathon. Conditioning that focuses on the distal and middle sites of the hamstring muscles may be more useful in improving recovery strategies after prolonged running.


Assuntos
Traumatismos em Atletas/diagnóstico por imagem , Traumatismos em Atletas/etiologia , Músculos Isquiossurais/diagnóstico por imagem , Músculos Isquiossurais/lesões , Corrida/fisiologia , Traumatismos em Atletas/fisiopatologia , Desempenho Atlético/fisiologia , Feminino , Músculos Isquiossurais/patologia , Humanos , Contração Isométrica/fisiologia , Japão , Imagem por Ressonância Magnética , Masculino , Fatores de Tempo , Torque , Adulto Jovem
13.
Arch Endocrinol Metab ; 64(3): 201-204, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32555986

RESUMO

OBJECTIVE: Autonomic nervous system, especially the sympathetic nervous system, may stimulate the expression of peroxisome proliferator-activated receptor γ coactivator-1α, which regulates irisin. This study aimed to explore whether there was any association between autonomic function as assessed by heart rate related indices and irisin release following acute exercise. SUBJECTS AND METHODS: Seventeen healthy adults were asked to perform an incremental exhaustive cycling as well as an incremental exhaustive running separately on different days. Heart rate was monitored, and blood samples were collected before, immediately, 10-, and 60-minutes post-exercise. Serum irisin was measured using ELISA kit. RESULTS: Markers for autonomic function, such as heart rate at rest, peak, or recovery, heart rate reserve, heart rate recovery, and chronotropic index, were comparable between cycling and running (all P > 0.10). Irisin was increased immediately following both exercise. No significant association was observed between heart rate at rest, peak, or recovery and irisin level at the corresponding time-point, as well as between heart rate reserve, heart rate recovery, or chronotropic index and exercise induced irisin release, with or without controlling for age, body mass index, and glucose (all P > 0.10). CONCLUSIONS: Autonomic function might not be associated with irisin release in healthy adults. Arch Endocrinol Metab. 2020;64(3):201-4.


Assuntos
Sistema Nervoso Autônomo/irrigação sanguínea , Sistema Nervoso Autônomo/fisiologia , Fibronectinas/sangue , Frequência Cardíaca/fisiologia , Corrida/fisiologia , Adulto , Estudos Cross-Over , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Distribuição Aleatória , Adulto Jovem
14.
PLoS One ; 15(6): e0233796, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497130

RESUMO

BACKGROUND: Rugby union match demands are complex, requiring the development of multiple physical qualities concurrently. Quantifying the physical qualities of age grade rugby union players is vital for practitioners to support athlete preparation and long-term development. AIM: This systematic review aimed to identify the methods used to quantify the physical qualities of male age grade (≤ Under-20) rugby union players, present the normative values for physical qualities, and compare physical qualities between age grades and positions. METHODS: Electronic databases were systematically reviewed from the earliest record to November 2019 using key words relating to sex, age, sport and physical testing. RESULTS: Forty-two studies evaluated the physical qualities of age grade rugby union players. Seventy-five tests were used to quantify body composition, muscular strength, muscular power, linear speed, change of direction ability, aerobic capacity and anaerobic endurance. Thirty-one studies met the eligibility criteria to present the physical qualities. Physical qualities differentiate between age groups below Under-16, while differences in older age groups (Under-16 to Under-20) are not clear. Positional differences are present with forwards possessing greater height, body mass, body fat percentage and strength while backs are faster and have greater aerobic capacities. CONCLUSIONS: A wide variety of tests are used to assess physical qualities limiting between study comparisons. Although differences in older age grades are unclear, older age groups (Under-19-20) generally performed better in physical tests. Positional differences are associated with match demands where forwards are exposed to less running but a greater number of collisions. Practitioners can use the results from this review to evaluate the physical qualities of age grade rugby union players to enhance training prescription, goal setting and player development. Future research should consider the use of national standardised testing batteries due to the inconsistency in testing methods and small samples limiting the reporting of positional differences.


Assuntos
Atletas , Desempenho Atlético/fisiologia , Teste de Esforço/métodos , Futebol Americano/fisiologia , Força Muscular/fisiologia , Adolescente , Composição Corporal/fisiologia , Tamanho Corporal/fisiologia , Criança , Humanos , Masculino , Resistência Física/fisiologia , Aptidão Física/fisiologia , Corrida/fisiologia , Adulto Jovem
16.
Am J Sports Med ; 48(7): 1711-1719, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32374673

RESUMO

BACKGROUND: Patellofemoral joint (PFJ) osteoarthritis may occur after anterior cruciate ligament reconstruction (ACLR). The mechanisms underpinning the development of PFJ osteoarthritis are not known but may relate to altered PFJ loading. Few studies have assessed PFJ loads during high-impact tasks, such as running, beyond the acute rehabilitation phase (ie, >12 months) after ACLR. PURPOSE/HYPOTHESIS: The purpose was to compare between-limb joint angles, joint moments, and PFJ contact force during running in individuals at 12 to 24 months after unilateral ACLR. We hypothesized that peak knee flexion angle, knee extension moment, and PFJ contact force during stance would be lower in the ACLR limb compared with the uninjured limb. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 55 participants (mean ± SD age, 28 ± 7 years), 12 to 24 months after ACLR, ran at a self-selected speed (2.9 ± 0.3 m/s). Measured kinematics and ground-reaction forces were input into musculoskeletal models to calculate joint moments and muscle forces. These values were subsequently input into a PFJ model to calculate contact force peak and impulse. Outcome measures were compared between the ACLR and uninjured limbs. RESULTS: In the ACLR limb, compared with the uninjured limb, the PFJ contact force displayed a lower peak (ACLR, 6.1 ± 1.3 body weight [BW]; uninjured, 6.7 ± 1.4 BW; P < .001) and impulse (ACLR, 0.72 ± 0.17 BW*seconds [BWs]; uninjured, 0.81 ± 0.17 BWs; P < .001). At the time of the peak PFJ contact force, the knee extension moment was lower in the ACLR limb (ACLR, 14.0 ± 2.4 %BW*height [%BW*HT]; uninjured, 15.5 ± 2.5 %BW*HT; P < .001). The opposite was true for the ankle plantarflexion moment (ACLR, 12.1 ± 2.6 %BW*HT; uninjured, 11.5 ± 2.7 %BW*HT; P = .019) and the hip extension moment (ACLR, 2.3 ± 2.5 %BW*HT; uninjured, 1.6 ± 2.3 %BW*HT; P = .013). The foot-ground center of pressure was located more anteriorly with respect to the ankle joint center (ACLR, 5.8 ± 0.9 %height [%HT]; uninjured, 5.4 ± 1.0 %HT; P = .001). No differences were found for the sagittal plane hip, knee, and ankle angles. CONCLUSION: The ACLR limb experienced lower peak PFJ loads during running, explained by a small anterior shift in the foot-ground center of pressure during stance that offloaded the torque demand away from the ACLR knee. CLINICAL RELEVANCE: Lower net PFJ loading during running in the ACLR limb more than 12 months after ACLR suggests that underloading might play a role in the onset of PFJ osteoarthritis after ACLR.


Assuntos
Lesões do Ligamento Cruzado Anterior/fisiopatologia , Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior , Articulação Patelofemoral/fisiologia , Corrida/fisiologia , Adolescente , Adulto , Reconstrução do Ligamento Cruzado Anterior/métodos , Fenômenos Biomecânicos , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/etiologia , Osteoartrite do Joelho/fisiopatologia , Torque , Suporte de Carga/fisiologia , Adulto Jovem
17.
J Sports Sci ; 38(16): 1869-1876, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32379007

RESUMO

Loading rates have been linked to running injuries, revealing persistent impact features that change direction among three-dimensional axes in different footwear and footstrike patterns. Extracting peak loads from ground reaction forces, however, can neglect the time-varying loading patterns experienced by the runner in each footfall. Following footwear and footstrike manipulations during laboratory-based overground running, we examined three-dimensional loading rate-time features in each direction (X, Y, Z) using principal component analysis. Twenty participants (9 M, 11 F, age: 25.3 ± 3.6 y) were analysed during 14 running trials in each of two footwear (cushioned and minimalist) and three footstrike conditions (forefoot, midfoot, rearfoot). Two principal components (PC) captured the primary loading rate-time features (PC1: 42.5% and PC2: 22.8% explained variance) and revealed interaction among axes, footwear, and footstrike conditions (PC1: F (2.1, 40.1) = 5.6, p = 0.007, η 2 = 0.23; PC2: F (2.0, 38.4) = 62.3, p < 0.001, η 2 = 0.77). Rearfoot running in cushioned footwear attenuated impact loads in the vertical direction, and forefoot running in minimalist footwear attenuated impact loads in the anterior-posterior and medial-lateral directions relative to forefoot running in cushioned shoes. Loading patterns depend on footwear and footstrike interactions, which require shoes that match the runner's footstrike pattern.


Assuntos
Pé/fisiologia , Corrida/fisiologia , Sapatos , Adulto , Fenômenos Biomecânicos , Desenho de Equipamento , Feminino , Análise da Marcha , Humanos , Masculino , Análise de Componente Principal , Corrida/lesões , Estudos de Tempo e Movimento , Adulto Jovem
18.
J Sports Sci ; 38(16): 1844-1858, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32449644

RESUMO

Running is a common exercise with numerous health benefits. Vertical ground reaction force (vGRF) influences running injury risk and running performance. Measurement of vGRF during running is now primarily constrained to a laboratory setting. The purpose of this study was to evaluate a new approach to measuring vGRF during running. This approach can be used outside of the laboratory and involves running shoes instrumented with novel piezoresponsive sensors and a standard accelerometer. Thirty-one individuals ran at three different speeds on a force-instrumented treadmill while wearing the instrumented running shoes. vGRF was predicted using data collected from the instrumented shoes, and predicted vGRF were compared to vGRF measured via the treadmill. Per cent error of the resulting predictions varied depending upon the predicted vGRF characteristic. Per cent error was relatively low for predicted vGRF impulse (2-7%), active peak vGRF (3-7%), and ground contact time (3-6%), but relatively high for predicted vGRF load rates (22-29%). These errors should decrease with future iterations of the instrumented shoes and collection of additional data from a more diverse sample. The novel technology described herein might become a feasible way to collect large amounts of vGRF data outside of the traditional biomechanics laboratory.


Assuntos
Acelerometria/instrumentação , Acelerometria/métodos , Nanocompostos , Corrida/fisiologia , Adolescente , Fenômenos Biomecânicos , Desenho de Equipamento , Feminino , Análise da Marcha , Humanos , Masculino , Modelos Estatísticos , Análise de Componente Principal , Adulto Jovem
19.
PLoS One ; 15(5): e0223698, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32401793

RESUMO

Limb length, cursoriality and speed have long been areas of significant interest in theropod paleobiology, since locomotory capacity, especially running ability, is critical in the pursuit of prey and to avoid becoming prey. The impact of allometry on running ability, and the limiting effect of large body size, are aspects that are traditionally overlooked. Since several different non-avian theropod lineages have each independently evolved body sizes greater than any known terrestrial carnivorous mammal, ~1000kg or more, the effect that such large mass has on movement ability and energetics is an area with significant implications for Mesozoic paleoecology. Here, using expansive datasets that incorporate several different metrics to estimate body size, limb length and running speed, we calculate the effects of allometry on running ability. We test traditional metrics used to evaluate cursoriality in non-avian theropods such as distal limb length, relative hindlimb length, and compare the energetic cost savings of relative hindlimb elongation between members of the Tyrannosauridae and more basal megacarnivores such as Allosauroidea or Ceratosauridae. We find that once the limiting effects of body size increase is incorporated there is no significant correlation to top speed between any of the commonly used metrics, including the newly suggested distal limb index (Tibia + Metatarsus/ Femur length). The data also shows a significant split between large and small bodied theropods in terms of maximizing running potential suggesting two distinct strategies for promoting limb elongation based on the organisms' size. For small and medium sized theropods increased leg length seems to correlate with a desire to increase top speed while amongst larger taxa it corresponds more closely to energetic efficiency and reducing foraging costs. We also find, using 3D volumetric mass estimates, that the Tyrannosauridae show significant cost of transport savings compared to more basal clades, indicating reduced energy expenditures during foraging and likely reduced need for hunting forays. This suggests that amongst theropods, hindlimb evolution was not dictated by one particular strategy. Amongst smaller bodied taxa the competing pressures of being both a predator and a prey item dominant while larger ones, freed from predation pressure, seek to maximize foraging ability. We also discuss the implications both for interactions amongst specific clades and Mesozoic paleobiology and paleoecological reconstructions as a whole.


Assuntos
Evolução Biológica , Dinossauros/anatomia & histologia , Dinossauros/fisiologia , Extremidade Inferior/anatomia & histologia , Extremidade Inferior/fisiologia , Animais , Tamanho Corporal , Conjuntos de Dados como Assunto , Comportamento Alimentar , Paleontologia , Comportamento Predatório , Corrida
20.
Science ; 368(6490)2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32355002

RESUMO

Repeated bouts of exercise condition muscle mitochondria to meet increased energy demand-an adaptive response associated with improved metabolic fitness. We found that the type 2 cytokine interleukin-13 (IL-13) is induced in exercising muscle, where it orchestrates metabolic reprogramming that preserves glycogen in favor of fatty acid oxidation and mitochondrial respiration. Exercise training-mediated mitochondrial biogenesis, running endurance, and beneficial glycemic effects were lost in Il13-/- mice. By contrast, enhanced muscle IL-13 signaling was sufficient to increase running distance, glucose tolerance, and mitochondrial activity similar to the effects of exercise training. In muscle, IL-13 acts through both its receptor IL-13Rα1 and the transcription factor Stat3. The genetic ablation of either of these downstream effectors reduced running capacity in mice. Thus, coordinated immunological and physiological responses mediate exercise-elicited metabolic adaptations that maximize muscle fuel economy.


Assuntos
Adaptação Fisiológica/imunologia , Glicogênio/metabolismo , Interleucina-13/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Resistência Física/imunologia , Animais , Glicemia/metabolismo , Linhagem Celular , Ácidos Graxos/metabolismo , Feminino , Humanos , Interleucina-13/sangue , Interleucina-13/genética , Subunidade alfa1 de Receptor de Interleucina-13/genética , Subunidade alfa1 de Receptor de Interleucina-13/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mioblastos/metabolismo , Oxirredução , Condicionamento Físico Animal , Corrida , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo
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