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1.
Artigo em Inglês | MEDLINE | ID: mdl-32163334

RESUMO

BACKGROUND: B-mode ultrasound is often used to quantify muscle architecture during movements. OBJECTIVES: 1) Systematically review the reliability of fascicle length (FL) and pennation angles (PA) measured using ultrasound during movements involving voluntary contractions, 2) systematically review the methods used in studies reporting reliability, discuss associated challenges, and provide recommendations to improve the reliability and validity of dynamic ultrasound measurements, 3) provide an overview of computational approaches for quantifying fascicle architecture, their validity, agreement with manual quantification of fascicle architecture, and advantages and drawbacks. METHODS: Three databases were searched until June 2019. Studies among healthy human individuals aged 17-85 years that investigated the reliability of FL or PA in lower extremity muscles during isoinertial movements and written in English were included. RESULTS: Thirty studies (n=340 participants) were included for reliability analyses. Between-session reliability as measured by coefficient of multiple correlations (CMC) and coefficient of variation (CV) was FL CMC: 0.89-0.96; CV: 8.3%, and PA CMC: 0.87-0.90; CV: 4.5-9.6%. Within-session reliability was FL CMC: 0.82-0.99; CV: 0.0-6.7%, and PA CMC: 0.91; CV: 0.0-15.0%. Manual analysis reliability was FL CMC: 0.89-0.96; CV: 0.0-15.9%; PA CMC: 0.84-0.90; CV: 2.0-9.8%. Computational analysis FL CMC was 0.82-0.99 and PA CV was 14.0-15.0%. Eighteen computational approaches were identified and these generally showed high agreement with manual analysis and high validity compared to phantoms or synthetic images. CONCLUSIONS: B-mode ultrasound is a reliable method to quantify fascicle architecture during movement. Additionally, computational approaches can provide a reliable and valid estimation of fascicle architecture.

2.
J Sports Sci ; 38(2): 214-230, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31795815

RESUMO

Injuries and lack of motivation are common reasons for discontinuation of running. Real-time feedback from wearables can reduce discontinuation by reducing injury risk and improving performance and motivation. There are however several limitations and challenges with current real-time feedback approaches. We discuss these limitations and challenges and provide a framework to optimise real-time feedback for reducing injury risk and improving performance and motivation. We first discuss the reasons why individuals run and propose that feedback targeted to these reasons can improve motivation and compliance. Secondly, we review the association of running technique and running workload with injuries and performance and we elaborate how real-time feedback on running technique and workload can be applied to reduce injury risk and improve performance and motivation. We also review different feedback modalities and motor learning feedback strategies and their application to real-time feedback. Briefly, the most effective feedback modality and frequency differ between variables and individuals, but a combination of modalities and mixture of real-time and delayed feedback is most effective. Moreover, feedback promoting perceived competence, autonomy and an external focus can improve motivation, learning and performance. Although the focus is on wearables, the challenges and practical applications are also relevant for laboratory-based gait retraining.


Assuntos
Desempenho Atlético/fisiologia , Desempenho Atlético/psicologia , Retroalimentação , Monitores de Aptidão Física , Motivação , Corrida/fisiologia , Corrida/psicologia , Traumatismos em Atletas/prevenção & controle , Fenômenos Biomecânicos , Marcha/fisiologia , Humanos , Percepção , Corrida/lesões
3.
Sports Med ; 2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31802395

RESUMO

BACKGROUND: Treadmills are often used in research, clinical practice, and training. Biomechanical investigations comparing treadmill and overground running report inconsistent findings. OBJECTIVE: This study aimed at comparing biomechanical outcomes between motorized treadmill and overground running. METHODS: Four databases were searched until June 2019. Crossover design studies comparing lower limb biomechanics during non-inclined, non-cushioned, quasi-constant-velocity motorized treadmill running with overground running in healthy humans (18-65 years) and written in English were included. Meta-analyses and meta-regressions were performed where possible. RESULTS: 33 studies (n = 494 participants) were included. Most outcomes did not differ between running conditions. However, during treadmill running, sagittal foot-ground angle at footstrike (mean difference (MD) - 9.8° [95% confidence interval: - 13.1 to - 6.6]; low GRADE evidence), knee flexion range of motion from footstrike to peak during stance (MD 6.3° [4.5 to 8.2]; low), vertical displacement center of mass/pelvis (MD - 1.5 cm [- 2.7 to - 0.8]; low), and peak propulsive force (MD - 0.04 body weights [- 0.06 to - 0.02]; very low) were lower, while contact time (MD 5.0 ms [0.5 to 9.5]; low), knee flexion at footstrike (MD - 2.3° [- 3.6 to - 1.1]; low), and ankle sagittal plane internal joint moment (MD - 0.4 Nm/kg [- 0.7 to - 0.2]; low) were longer/higher, when pooled across overground surfaces. Conflicting findings were reported for amplitude of muscle activity. CONCLUSIONS: Spatiotemporal, kinematic, kinetic, muscle activity, and muscle-tendon outcome measures are largely comparable between motorized treadmill and overground running. Considerations should, however, particularly be given to sagittal plane kinematic differences at footstrike when extrapolating treadmill running biomechanics to overground running. Protocol registration CRD42018083906 (PROSPERO International Prospective Register of Systematic Reviews).

4.
Sports Med ; 49(5): 763-782, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30847825

RESUMO

BACKGROUND: Treadmills are routinely used to assess running performance and training parameters related to physiological or perceived effort. These measurements are presumed to replicate overground running but there has been no systematic review comparing performance, physiology and perceived effort between treadmill and overground running. OBJECTIVE: The objective of this systematic review was to compare physiological, perceptual and performance measures between treadmill and overground running in healthy adults. METHODS: AMED (Allied and Contemporary Medicine), CINAHL (Cumulative Index to Nursing and Allied Health), EMBASE, MEDLINE, SCOPUS, SPORTDiscus and Web of Science databases were searched from inception until May 2018. Included studies used a crossover study design to compare physiological (oxygen uptake [[Formula: see text]O2], heart rate [HR], blood lactate concentration [La]), perceptual (rating of perceived exertion [RPE] and preferred speed) or running endurance and sprint performance (i.e. time trial duration or sprint speed) outcomes between treadmill (motorised or non-motorised) and overground running. Physiological outcomes were considered across submaximal, near-maximal and maximal running intensity subgroups. Meta-analyses were used to determine mean difference (MD) or standardised MD (SMD) ± 95% confidence intervals. RESULTS: Thirty-four studies were included. Twelve studies used a 1% grade for the treadmill condition and three used grades > 1%. Similar [Formula: see text]O2 but lower La occurred during submaximal motorised treadmill running at 0% ([Formula: see text]O2 MD: - 0.55 ± 0.93 mL/kg/min; La MD: - 1.26 ± 0.71 mmol/L) and 1% ([Formula: see text]O2 MD: 0.37 ± 1.12 mL/kg/min; La MD: - 0.52 ± 0.50 mmol/L) grade than during overground running. HR and RPE during motorised treadmill running were higher at faster submaximal speeds and lower at slower submaximal speeds than during overground running. [Formula: see text]O2 (MD: - 1.25 ± 2.09 mL/kg/min) and La (MD: - 0.54 ± 0.63 mmol/L) tended to be lower, but HR (MD: 0 ± 1 bpm), and RPE (MD: - 0.4 ± 2.0 units [6-20 scale]) were similar during near-maximal motorised treadmill running to during overground running. Maximal motorised treadmill running caused similar [Formula: see text]O2 (MD: 0.78 ± 1.55 mL/kg/min) and HR (MD: - 1 ± 2 bpm) to overground running. Endurance performance was poorer (SMD: - 0.50 ± 0.36) on a motorised treadmill than overground but sprint performance varied considerably and was not significantly different (MD: - 1.4 ± 5.8 km/h). CONCLUSIONS: Some, but not all, variables differ between treadmill and overground running, and may be dependent on the running speed at which they are assessed. PROTOCOL REGISTRATION: CRD42017074640 (PROSPERO International Prospective Register of Systematic Reviews).

5.
J Strength Cond Res ; 33(12): 3302-3308, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29489726

RESUMO

Macdonald, B, O'Neill, J, Pollock, N, and Van Hooren, B. Single-leg Roman chair hold is more effective than the Nordic hamstring curl in improving hamstring strength-endurance in Gaelic footballers with previous hamstring injury. J Strength Cond Res 33(12): 3302-3308, 2019-Poor hamstring strength-endurance is a risk factor for hamstring injuries. This study investigated the effectiveness of the single-leg Roman hold and Nordic hamstring curl in improving hamstring strength-endurance. Twelve Gaelic footballers (mean ± SD age, height, and mass were 25.17 ± 3.46 years, 179.25 ± 5.88 cm, 85.75 ± 4.75 kg, respectively) with a history of hamstring injury were randomized into 2 groups that performed 6 weeks of either Nordic hamstring curl or single-leg Roman chair hold training. The single-leg hamstring bridge (SLHB) was measured before and after intervention. The Roman chair group showed a very likely moderate magnitude improvement on SLHB performance for both legs (23.7% for the previously injured leg [90% confidence interval 9.6-39.6%] and 16.9% for the noninjured leg [6.2-28.8%]). The Nordic curl group showed a likely trivial change in SLHB performance for the noninjured leg (-2.1% [-6.7 to 2.6%]) and an unclear, but possibly trivial change for the previously injured leg (0.3% [-5.6 to 6.6%]). The Roman chair group improved very likely more with a moderate magnitude in both the noninjured (19.5% [8.0-32.2%]) and the previously injured leg (23.3% [8.5-40.0%]) compared with the Nordic curl group. This study demonstrated that 6-week single-leg Roman chair training substantially improved SLHB performance, suggesting that it may be an efficacious strategy to mitigate hamstring (re-) injury risk. Conversely, 6-week Nordic curl training did not substantially improve SLHB performance, suggesting this may not be the intervention of choice for modifying this risk factor.


Assuntos
Traumatismos em Atletas/prevenção & controle , Músculos Isquiotibiais/fisiologia , Força Muscular , Resistência Física , Treinamento de Resistência/métodos , Adulto , Traumatismos em Atletas/fisiopatologia , Músculos Isquiotibiais/lesões , Humanos , Masculino , Futebol/lesões , Adulto Jovem
6.
Sports Med ; 48(7): 1575-1595, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29663142

RESUMO

It is widely believed that an active cool-down is more effective for promoting post-exercise recovery than a passive cool-down involving no activity. However, research on this topic has never been synthesized and it therefore remains largely unknown whether this belief is correct. This review compares the effects of various types of active cool-downs with passive cool-downs on sports performance, injuries, long-term adaptive responses, and psychophysiological markers of post-exercise recovery. An active cool-down is largely ineffective with respect to enhancing same-day and next-day(s) sports performance, but some beneficial effects on next-day(s) performance have been reported. Active cool-downs do not appear to prevent injuries, and preliminary evidence suggests that performing an active cool-down on a regular basis does not attenuate the long-term adaptive response. Active cool-downs accelerate recovery of lactate in blood, but not necessarily in muscle tissue. Performing active cool-downs may partially prevent immune system depression and promote faster recovery of the cardiovascular and respiratory systems. However, it is unknown whether this reduces the likelihood of post-exercise illnesses, syncope, and cardiovascular complications. Most evidence indicates that active cool-downs do not significantly reduce muscle soreness, or improve the recovery of indirect markers of muscle damage, neuromuscular contractile properties, musculotendinous stiffness, range of motion, systemic hormonal concentrations, or measures of psychological recovery. It can also interfere with muscle glycogen resynthesis. In summary, based on the empirical evidence currently available, active cool-downs are largely ineffective for improving most psychophysiological markers of post-exercise recovery, but may nevertheless offer some benefits compared with a passive cool-down.


Assuntos
Exercício/fisiologia , Glicogênio/metabolismo , Músculo Esquelético/fisiopatologia , Mialgia , Austrália , Feminino , Humanos , Masculino , Contração Muscular
8.
J Strength Cond Res ; 32(1): e2-e3, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29257798
9.
J Strength Cond Res ; 31(8): 2324-2337, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28737611

RESUMO

Van Hooren, B, Bosch, F, and Meijer, K. Can resistance training enhance the rapid force development in unloaded dynamic isoinertial multi-joint movements? A systematic review. J Strength Cond Res 31(8): 2324-2337, 2017-The objectives of this systematic review were to (a) evaluate whether resistance training can improve the rapid force development in unloaded dynamic isoinertial multi-joint movements and (b) investigate whether these effects differ between untrained/recreationally trained and well-trained individuals. Four electronic databases were screened for studies that measured the effects of resistance training on rapid force development in unloaded dynamic isoinertial multi-joint movements. Twelve studies with a total of 271 participants were included. 10/26 (38%) and 6/14 (43%) of the measures of rapid force development in unloaded dynamic isoinertial multi-joint movements significantly improved following training in the untrained/recreationally trained and well-trained individuals, respectively. Additionally, 7/14 (50%) and 3/12 (25%) of the measures significantly improved during a countermovement and squat jump in the untrained/recreationally trained individuals and 4/6 (67%) and 2/8 (25%) significantly improved during a countermovement and squat jump in the well-trained individuals, respectively. These findings indicate that resistance training has a limited transfer to rapid force development in unloaded dynamic isoinertial multi-joint movements, especially for well-trained individuals and in movements without a countermovement. Furthermore, rapid force development has likely a limited transfer from movements with countermovement to movements without a countermovement and from bilateral movements to unilateral movements. Therefore, it is important to specifically mimic the actual sport movement in order to maximize the transfer of training and testing.


Assuntos
Atletas , Articulações/fisiologia , Força Muscular/fisiologia , Treinamento de Resistência/métodos , Feminino , Humanos , Masculino , Esportes
10.
J Strength Cond Res ; 31(7): 2011-2020, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28640774

RESUMO

Van Hooren, B and Zolotarjova, J. The difference between countermovement and squat jump performances: a review of underlying mechanisms with practical applications. J Strength Cond Res 31(7): 2011-2020, 2017-Two movements that are widely used to monitor athletic performance are the countermovement jump (CMJ) and squat jump (SJ). Countermovement jump performance is almost always better than SJ performance, and the difference in performance is thought to reflect an effective utilization of the stretch-shortening cycle. However, the mechanisms responsible for the performance-enhancing effect of the stretch-shortening cycle are frequently undefined. Uncovering and understanding these mechanisms is essential to make an inference regarding the difference between the jumps. Therefore, we will review the potential mechanisms that explain the better performance in a CMJ as compared with a SJ. It is concluded that the difference in performance may primarily be related to the greater uptake of muscle slack and the buildup of stimulation during the countermovement in a CMJ. Elastic energy may also have a small contribution to an enhanced CMJ performance. Therefore, a larger difference between the jumps is not necessarily a better indicator of high-intensity sports performance. Although a larger difference may reflect the utilization of elastic energy in a small-amplitude CMJ as a result of a well-developed capability to co-activate muscles and quickly build up stimulation, a larger difference may also reflect a poor capability to reduce the degree of muscle slack and build up stimulation in the SJ. Because the capability to reduce the degree of muscle slack and quickly build up stimulation in the SJ may be especially important to high-intensity sports performance, training protocols might concentrate on attaining a smaller difference between the jumps.


Assuntos
Desempenho Atlético/fisiologia , Exercício/fisiologia , Músculo Esquelético/fisiologia , Fenômenos Biomecânicos , Humanos , Masculino
11.
J Sports Sci ; 35(23): 2313-2321, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27937671

RESUMO

It is widely assumed that there is an eccentric hamstring muscle fibre action during the swing phase of high-speed running. However, animal and modelling studies in humans show that the increasing distance between musculotendinous attachment points during forward swing is primarily due to passive lengthening associated with the take-up of muscle slack. Later in the swing phase, the contractile element (CE) maintains a near isometric action while the series elastic (tendinous) element first stretches as the knee extends, and then recoils causing the swing leg to forcefully retract prior to ground contact. Although modelling studies showed some active lengthening of the contractile (muscular) element during the mid-swing phase of high-speed running, we argue that the increasing distance between the attachment points should not be interpreted as an eccentric action of the CE due to the effects of muscle slack. Therefore, there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstrings CE during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this, we propose that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running.


Assuntos
Músculos Isquiotibiais/fisiologia , Contração Muscular/fisiologia , Corrida/fisiologia , Animais , Fenômenos Biomecânicos , Simulação por Computador , Elasticidade/fisiologia , Músculos Isquiotibiais/anatomia & histologia , Músculos Isquiotibiais/lesões , Humanos , Modelos Animais , Condicionamento Físico Humano/métodos , Corrida/lesões
12.
J Sports Sci ; 35(23): 2322-2333, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27935419

RESUMO

We have previously argued that there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstring muscle fibres during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this we suggested that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running. In this review we argue that some of the presumed beneficial adaptations following eccentric training may actually not be related to the eccentric muscle fibre action, but to other factors such as exercise intensity. Furthermore, we discuss several disadvantages associated with commonly used eccentric hamstring exercises. Subsequently, we argue that high-intensity isometric exercises in which the series elastic element stretches and recoils may be equally or even more effective at conditioning the hamstrings for high-speed running, since they also avoid some of the negative side effects associated with eccentric training. We provide several criteria that exercises should fulfil to effectively condition the hamstrings for high-speed running. Adherence to these criteria will guarantee specificity with regards to hamstrings functioning during running. Practical examples of isometric exercises that likely meet several criteria are provided.


Assuntos
Músculos Isquiotibiais/fisiologia , Contração Muscular/fisiologia , Corrida/fisiologia , Adaptação Fisiológica , Animais , Fenômenos Biomecânicos , Simulação por Computador , Elasticidade/fisiologia , Músculos Isquiotibiais/anatomia & histologia , Músculos Isquiotibiais/lesões , Humanos , Modelos Animais , Condicionamento Físico Humano/métodos , Corrida/lesões
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