RESUMO
The purpose of this study was to examine whether drop height-induced changes in leg muscle activity during drop jumps (DJ) are additionally modulated by surface condition. Twenty-four healthy participants (23.7 ± 1.8 years) performed DJs on a force plate on stable, unstable, and highly unstable surfaces using different drop heights (i.e., 20 cm, 40 cm, 60 cm). Electromyographic (EMG) activity of soleus (SOL), gastrocnemius (GM), tibialis anterior (TA) muscles and coactivation of TA/SOL and TA/GM were analyzed for time intervals 100 ms prior to ground contact (preactivation) and 30-60 ms after ground contact [short latency response (SLR)]. Increasing drop heights resulted in progressively increased SOL and GM activity during preactivation and SLR (P < 0.01; 1.01 ≤ d ≤ 5.34) while TA/SOL coactivation decreased (P < 0.05; 0.51 ≤ d ≤ 3.01). Increasing surface instability produced decreased activities during preactivation (GM) and SLR (GM, SOL) (P < 0.05; 1.36 ≤ d ≤ 4.30). Coactivation increased during SLR (P < 0.05; 1.50 ≤ d ≤ 2.58). A significant drop height × surface interaction was observed for SOL during SLR. Lower SOL activity was found on unstable compared to stable surfaces for drop heights ≥40 cm (P < 0.05; 1.25 ≤ d ≤ 2.12). Findings revealed that instability-related changes in activity of selected leg muscles are minimally affected by drop height.
Assuntos
Desempenho Atlético/fisiologia , Músculo Esquelético/fisiologia , Adulto , Fenômenos Biomecânicos , Eletromiografia , Feminino , Humanos , Perna (Membro) , Masculino , Propriedades de Superfície , Suporte de Carga , Adulto JovemRESUMO
It has previously been shown that fatigue and unstable surfaces affect jump performance. However, the combination thereof is unresolved. Thus, the purpose of this study was to examine the effects of fatigue and surface instability on jump performance and leg muscle activity. Twenty elite volleyball players (18 ± 2 years) performed repetitive vertical double-leg box jumps until failure. Before and after a fatigue protocol, jump performance (i.e., jump height) and electromyographic activity of selected lower limb muscles were recorded during drop jumps (DJs) and countermovement jumps (CMJs) on a force plate on stable and unstable surfaces (i.e., balance pad on top of force plate). Jump performance (3-7%; P < 0.05; 1.14 ≤ d ≤ 2.82), and muscle activity (2-27%; P < 0.05; 0.59 ≤ d ≤ 3.13) were lower following fatigue during DJs and CMJs, and on unstable compared with stable surfaces during DJs only (jump performance: 8%; P < 0.01; d = 1.90; muscle activity: 9-25%; P < 0.05; 1.08 ≤ d ≤ 2.54). No statistically significant interactions of fatigue by surface condition were observed. Our findings revealed that fatigue impairs neuromuscular performance during DJs and CMJs in elite volleyball players, whereas surface instability affects neuromuscular DJ performance only. Absent fatigue × surface interactions indicate that fatigue-induced changes in jump performance are similar on stable and unstable surfaces in jump-trained athletes.
Assuntos
Desempenho Atlético/fisiologia , Fadiga/fisiopatologia , Movimento/fisiologia , Voleibol/fisiologia , Adolescente , Eletromiografia , Fadiga/complicações , Feminino , Músculos Isquiossurais/fisiologia , Humanos , Masculino , Músculo Quadríceps/fisiologia , Propriedades de Superfície , Adulto JovemRESUMO
Cross-sectional studies revealed that inclusion of unstable elements in core-strengthening exercises produced increases in trunk muscle activity and thus potential extra stimuli to induce more pronounced performance enhancements in youth athletes. Thus, the purpose of the study was to investigate changes in neuromuscular and athletic performance following core strength training performed on unstable (CSTU) compared with stable surfaces (CSTS) in youth soccer players. Thirty-nine male elite soccer players (age: 17 ± 1 years) were assigned to two groups performing a progressive core strength-training program for 9 weeks (2-3 times/week) in addition to regular in-season soccer training. CSTS group conducted core exercises on stable (i.e., floor, bench) and CSTU group on unstable (e.g., Thera-Band® Stability Trainer, Togu© Swiss ball) surfaces. Measurements included tests for assessing trunk muscle strength/activation, countermovement jump height, sprint time, agility time, and kicking performance. Statistical analysis revealed significant main effects of test (pre vs post) for trunk extensor strength (5%, P < 0.05, d = 0.86), 10-20-m sprint time (3%, P < 0.05, d = 2.56), and kicking performance (1%, P < 0.01, d = 1.28). No significant Group × test interactions were observed for any variable. In conclusion, trunk muscle strength, sprint, and kicking performance improved following CSTU and CSTS when conducted in combination with regular soccer training.
Assuntos
Desempenho Atlético/fisiologia , Força Muscular/fisiologia , Treinamento Resistido/métodos , Futebol/fisiologia , Adolescente , Humanos , MasculinoRESUMO
The purpose of this study was to investigate the effects of plyometric training on stable (SPT) vs. highly unstable surfaces (IPT) on athletic performance in adolescent soccer players. 24 male sub-elite soccer players (age: 15±1 years) were assigned to 2 groups performing plyometric training for 8 weeks (2 sessions/week, 90 min each). The SPT group conducted plyometrics on stable and the IPT group on unstable surfaces. Tests included jump performance (countermovement jump [CMJ] height, drop jump [DJ] height, DJ performance index), sprint time, agility and balance. Statistical analysis revealed significant main effects of time for CMJ height (p<0.01, f=1.44), DJ height (p<0.01, f=0.62), DJ performance index (p<0.05, f=0.60), 0-10-m sprint time (p<0.05, f=0.58), agility (p<0.01, f=1.15) and balance (p<0.05, 0.46≤f≤1.36). Additionally, a Training group×Time interaction was found for CMJ height (p<0.01, f=0.66) in favor of the SPT group. Following 8 weeks of training, similar improvements in speed, agility and balance were observed in the IPT and SPT groups. However, the performance of IPT appears to be less effective for increasing CMJ height compared to SPT. It is thus recommended that coaches use SPT if the goal is to improve jump performance.
Assuntos
Desempenho Atlético/fisiologia , Exercício Pliométrico/métodos , Futebol/fisiologia , Adolescente , Teste de Esforço/métodos , Humanos , Masculino , Força Muscular/fisiologiaRESUMO
This study investigated sex-specific effects of surface instability on kinetics and lower extremity kinematics during drop jumping and landing. Ground reaction forces as well as knee valgus and flexion angles were tested in 14 males (age: 23±2 years) and 14 females (age: 24±3 years) when jumping and landing on stable and unstable surfaces. Jump height was found to be significantly lower (9%, p<0.001) when drop jumps were performed on unstable vs. stable surface. Significantly higher peak ground reaction forces were observed when jumping was performed on unstable versus stable surfaces (5%, p=0.022). Regarding frontal plane kinematics during jumping and landing, knee valgus angles were higher on unstable compared to stable surfaces (19-32%, p<0.05). Additionally, at the onset of ground contact during landings, females showed higher knee valgus angles than males (222%, p=0.027). Sagittal plane kinematics indicated significantly smaller knee flexion angles (6-35%, p<0.05) when jumping and landing on unstable vs. stable surfaces. During drop jumps and landings, women showed smaller knee flexion angles at ground contact compared to men (27-33%, p<0.05). These findings imply that knee motion strategies were modified by surface instability and sex during drop jumps and landings.
Assuntos
Planejamento Ambiental , Extremidade Inferior/fisiologia , Exercício Pliométrico , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Movimento , Fatores Sexuais , Adulto JovemRESUMO
The proportion of elderly people in societies of western industrialized countries is continuously rising. Biologic aging induces deficits in balance and muscle strength/power in old age, which is responsible for an increased prevalence of falls. Therefore, nationwide and easy-to-administer fall prevention programs have to be developed in order to contribute to the autonomy and quality of life in old age and to help reduce the financial burden on the public health care system due to the treatment of fall-related injuries. This narrative (qualitative) literature review deals with a) the reasons for an increased prevalence of falls in old age, b) important clinical tests for fall-risk assessment, and c) evidence-based intervention/training programs for fall prevention in old age. The findings of this literature review are based on a cost-free practice guide that is available to the public (via the internet) and that was created by an expert panel (i.e., geriatricians, exercise scientists, physiotherapists, geriatric therapists). The present review provides the scientific foundation of the practice guide.
Assuntos
Acidentes por Quedas/prevenção & controle , Terapia por Exercício/normas , Avaliação Geriátrica/estatística & dados numéricos , Exame Físico/normas , Guias de Prática Clínica como Assunto , Idoso , Idoso de 80 Anos ou mais , Feminino , Avaliação Geriátrica/métodos , Alemanha , Humanos , MasculinoRESUMO
The objective of this study was to examine the impact of an indoor climbing training and detraining program on core/handgrip strength and trunk mobility in men and women. 28 young sedentary adults participated in this study and were assigned to an intervention (30±3 years) or a control (29±2 years) group. The intervention group participated in 8 weeks (2 times/week) of indoor climbing training, followed by 8 weeks of detraining. Tests included the measurement of maximal isometric strength (MIS) of the trunk flexors/extensors, the assessment of trunk mobility in the sagittal (SAP) and the coronal (CRP) plane as well as testing of handgrip strength. After training, significant improvements were observed in MIS of the trunk flexors/extensors (~19-22%, all p<0.01), in trunk mobility in SAP/CRP (~14-19%, all p<0.01), and in handgrip strength (~5%, p<0.01). During detraining, MIS (~12-13%, all p<0.01) and trunk mobility (~7-10%, all p<0.01) deteriorated significantly, whereas handgrip strength remained. This indoor climbing training program conducted in sedentary adults proved to be feasible (i. e., attendance rate of 89.4%) and effective. It is suggested that indoor climbing should be permanently conducted to maintain the observed improvements in core muscle strength and trunk mobility.
Assuntos
Montanhismo/fisiologia , Força Muscular/fisiologia , Adulto , Feminino , Força da Mão/fisiologia , Humanos , Contração Isométrica/fisiologia , Estudos Longitudinais , Masculino , Músculo Esquelético/fisiologia , Comportamento SedentárioRESUMO
BACKGROUND: Aerobic exercise (AE) may slow age-related cognitive decline. However, such cognition-sparing effects are not uniform across cognitive domains and studies. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation and is also emerging as a potential alternative to pharmaceutical therapies. Like AE, the effectiveness of tDCS is also inconsistent for reducing cognitive impairment in ageing. The unexplored possibility exists that pairing AE and tDCS could produce synergistic effects and reciprocally augment cognition-improving effects in older individuals with and without cognitive impairments. Previous research found such synergistic effects on cognition when cognitive training is paired with tDCS in older individuals with and without mild cognitive impairment (MCI) or dementia. AIM: The purpose of this systematic review with meta-analysis was to explore if pairing AE with tDCS could augment singular effects of AE and tDCS on global cognition (GC), working memory (WM) and executive function (EF) in older individuals with or without MCI and dementia. METHODS: Using a PRISMA-based systematic review, we compiled studies that examined the effects of AE alone, tDCS alone, and AE and tDCS combined on cognitive function in older individuals with and without mild cognitive impairment (MCI) or dementia. Using a PICOS approach, we systematically searched PubMed, Scopus and Web of Science searches up to December 2021, we focused on 'MoCA', 'MMSE', 'Mini-Cog' (measures) and 'cognition', 'cognitive function', 'cognitive', 'cognitive performance', 'executive function', 'executive process', 'attention', 'memory', 'memory performance' (outcome terms). We included only randomized controlled trials (RTC) in humans if available in English full text over the past 20 years, with participants' age over 60. We assessed the methodological quality of the included studies (RTC) by the Physiotherapy Evidence Database (PEDro) scale. RESULTS: Overall, 68 studies were included in the meta-analyses. AE (ES = 0.56 [95% CI: 0.28-0.83], p = 0.01) and tDCS (ES = 0.69 [95% CI: 0.12-1.26], p = 0.02) improved GC in all three groups of older adults combined (healthy, MCI, demented). In healthy population, AE improved GC (ES = 0.46 [95% CI: 0.22-0.69], p = 0.01) and EF (ES = 0.27 [95% CI: 0.05-0.49], p = 0.02). AE improved GC in older adults with MCI (ES = 0.76 [95% CI: 0.21-1.32], p = 0.01). tDCS improved GC (ES = 0.69 [90% CI: 0.12-1.26], p = 0.02), all three cognitive function (GC, WM and EF) combined in older adults with dementia (ES = 1.12 [95% CI: 0.04-2.19], p = 0.04) and improved cognitive function in older adults overall (ES = 0.69 [95% CI: 0.20-1,18], p = 0.01). CONCLUSION: Our systematic review with meta-analysis provided evidence that beyond the cardiovascular and fitness benefits of AE, pairing AE with tDCS may have the potential to slow symptom progression of cognitive decline in MCI and dementia. Future studies will examine the hypothesis of this present review that a potentiating effect would incrementally improve cognition with increasing severity of cognitive impairment.
Assuntos
Disfunção Cognitiva , Demência , Estimulação Transcraniana por Corrente Contínua , Idoso , Disfunção Cognitiva/terapia , Exercício Físico , Humanos , Preparações FarmacêuticasRESUMO
BACKGROUND: Adiposity, low aerobic fitness and low levels of activity are all associated with clustered cardiovascular disease risk in children and their high prevalence represents a major public health concern. OBJECTIVE: The aim of this study is to investigate the relationship of objectively measured physical activity (PA) with motor skills (agility and balance), aerobic fitness and %body fat in young children. DESIGN: This study is a cross-sectional and longitudinal analyses using mixed linear models. Longitudinal data were adjusted for baseline outcome parameters. SUBJECTS: In all, 217 healthy preschool children (age 4-6 years, 48% boys) participated in this study. MEASUREMENTS: PA (accelerometers), agility (obstacle course), dynamic balance (balance beam), aerobic fitness (20-m shuttle run) and %body fat (bioelectric impedance) at baseline and 9 months later. RESULTS: PA was positively associated with both motor skills and aerobic fitness at baseline as well as with their longitudinal changes. Specifically, only vigorous, but not total or moderate PA, was related to changes in aerobic fitness. Higher PA was associated with less %body fat at baseline, but not with its change. Conversely, baseline motor skills, aerobic fitness or %body fat were not related to changes in PA. CONCLUSION: In young children, baseline PA was associated with improvements in motor skills and in aerobic fitness, an important determinant of cardiovascular risk.
Assuntos
Tecido Adiposo/fisiologia , Atividade Motora/fisiologia , Destreza Motora/fisiologia , Obesidade/prevenção & controle , Aptidão Física/fisiologia , Doenças Cardiovasculares/fisiopatologia , Doenças Cardiovasculares/prevenção & controle , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Modelos Lineares , Estudos Longitudinais , Masculino , Obesidade/fisiopatologia , Fatores de Risco , Inquéritos e QuestionáriosRESUMO
The prevalence of sustaining fall-related injuries is high in the middle-aged workforce. Deficits in postural control/muscle strength represent important fall-risk factors. The objective of this study was to examine the impact of balance and strength training followed by detraining on postural control and muscle strength in the workforce. Thirty-two adults with sedentary office work participated in this study and were assigned to an intervention (age 56.0 ± 3.7 yrs) or a control group (age 55.5 ± 3.4 yrs). The intervention group participated in 8 weeks of balance and strength training conducted at the worksite, followed by 8 weeks of detraining. Tests included the measurement of (a) total centre of pressure (COP) displacements during one-legged standing, (b) gait velocity and stride-to-stride variability, (c) peak isometric/isokinetic torque and rate of torque development (RTD) of the plantar flexors, and (d) jumping height. After training, significant improvements in COP displacements, gait velocity, peak isometric/isokinetic torque, RTD, and jumping height were observed. During detraining, muscle strength deteriorated, whereas postural control improved. This fall-preventive training program conducted at the worksite proved to be feasible and effective. It is suggested that this training program should be permanently conducted to maintain/improve muscle strength.
Assuntos
Promoção da Saúde , Força Muscular/fisiologia , Equilíbrio Postural/fisiologia , Acidentes por Quedas/prevenção & controle , Europa (Continente) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Saúde Ocupacional , Inquéritos e Questionários , Torque , CaminhadaRESUMO
It has been demonstrated that strength training can be organized in children in a safe and effective way. However, there is limited data regarding its impact on muscle hypertrophy. This study investigated the effects of a high-intensity strength training (HIS) on knee extensor/flexor strength, countermovement (CMJ) jumping height, postural control, soft lean mass and muscle cross-sectional area (CSA) of the dominant leg in prepubertal children. Thirty-two children participated in this study and were assigned to an intervention (INT; N=17) or a control class ( N=15). The INT participated in 10 weeks of weight-machine based HIS integrated in physical education. Pre/post tests included the measurements of peak torque of the knee extensors/flexors at 60 and 180°/s, CMJ jumping height, postural sway, soft lean mass of the leg by bioelectrical impedance analysis, and CSA (m. quadriceps) by magnetic resonance imaging. HIS resulted in significant increases in knee extensor/flexor peak torque (60°/s and 180°/s). HIS did not produce significant changes in CMJ jumping height, postural sway, soft lean mass, and CSA. Although HIS was effective at increasing peak torque of the knee extensors/flexors in children, it was unable to affect muscle size. It appears that neural factors rather than muscle hypertrophy account for the observed strength gains in children.
Assuntos
Músculo Esquelético/metabolismo , Treinamento Resistido/métodos , Criança , Impedância Elétrica , Feminino , Humanos , Masculino , SuíçaRESUMO
This systematic review and meta-analysis aimed to examine the effects of home-based exercise programmes on measures of physical-fitness in healthy older adults. Seventeen randomized-controlled trials were included with a total of 1,477 participants. Results indicated small effects of home-based training on muscle strength (between-study standardised-mean-difference [SMD] = 0.30), muscle power (SMD = 0.43), muscular endurance (SMD = 0.28), and balance (SMD = 0.28). We found no statistically significant effects for single-mode strength vs. multimodal training (e.g., combined balance, strength, and flexibility exercises) on measures of muscle strength and balance. Single-mode strength training had moderate effects on muscle strength (SMD = 0.51) and balance (SMD = 0.65) while multimodal training had no statistically significant effects on muscle strength and balance. Irrespective of the training type, >3 weekly sessions produced larger effects on muscle strength (SMD = 0.45) and balance (SMD = 0.37) compared with ≤3 weekly sessions (muscle strength: SMD = 0.28; balance: SMD = 0.24). For session-duration, only ≤30 min per-session produced small effects on muscle strength (SMD = 0.35) and balance (SMD = 0.34). No statistically significant differences were observed between all independently-computed single-training factors. Home-based exercise appears effective to improve components of health- (i.e., muscle strength and muscular endurance) and skill-related (i.e., muscle power, balance) physical-fitness. Therefore, in times of restricted physical activity due to pandemics, home-based exercises constitute an alternative to counteract physical inactivity and preserve/improve the health and fitness of healthy older adults aged 65-to-83 years.
Assuntos
COVID-19 , Treinamento Resistido , Idoso , Idoso de 80 Anos ou mais , Terapia por Exercício , Humanos , Força Muscular , Aptidão Física , SARS-CoV-2RESUMO
The prevalence of sustaining a sport injury is high in adults. Deficits in postural control/muscle strength represent important injury-risk factors. Thus, the purpose of this study was to investigate the impact of a specific type of balance training, i. e. slackline training, followed by detraining on balance and strength performance. Twenty-seven adults participated in this study and were assigned to an intervention (age 22.8±3.3 yrs) or a control group (age 23.9±4.4 yrs). The intervention group participated in 4 weeks of slackline training on nylon webbings. Detraining lasted 4 weeks. Tests included the measurement of (A) total centre of pressure displacements during one-legged standing on a balance platform and during the compensation of a perturbation impulse, (B) maximal torque and rate of force development (RFD) of the plantar flexors on an isokinetic device, and (C) jumping height on a force platform. After training, no significant interaction effects were observed for variables of static/dynamic postural control, maximal torque, and jumping height. Training-induced improvements were found for RFD. After the withdrawal of the training stimulus, RFD slightly decreased. Given that the promotion of balance and strength is important for injury prevention, changes in RFD only might not be sufficient to produce an injury-preventive effect.
Assuntos
Traumatismos em Atletas/prevenção & controle , Educação Física e Treinamento/métodos , Equilíbrio Postural/fisiologia , Adulto , Feminino , Humanos , Perna (Membro)/fisiologia , Masculino , Movimento/fisiologia , Força Muscular/fisiologia , Torque , Adulto JovemRESUMO
Age-related impairment in gait patterns when simultaneously performing cognitive (CI) and/or motor (MI) interference tasks are associated with an increased risk of falling in seniors. The objective of this study was to investigate the impact of balance training (BT) on walking performance with and without concurrently performing a CI and/or MI task in seniors. Twenty healthy women (n=14) and men (n=6) were assigned to either an intervention (n=11, age 71.9+/-4.8 yrs) or a control group (n=9, age 74.9+/-6.3 yrs). The intervention group conducted a six week BT (3/week). Pre and post tests included the assessment of stride-to-stride variability during single (walking), dual (CI or MI+walking), and triple (CI+MI+walking) task walking on an instrumented walkway. BT resulted in statistically significant reductions in stride time variability under single (p=0.02, Delta34.8%) but not dual or triple-task walking. Significant improvements in the MI task (p=0.05, Delta39.1%), but not in the CI task were found while walking. Findings showed that improved performance during single-task walking did not transfer to walking under dual or triple-task conditions suggesting multi-task BT as an alternative training modality. Improvement of the secondary motor but not cognitive task may indicate the need for the involvement of motor and particularly cognitive tasks during BT.
Assuntos
Marcha/fisiologia , Equilíbrio Postural/fisiologia , Análise e Desempenho de Tarefas , Idoso , Idoso de 80 Anos ou mais , Atenção/fisiologia , Feminino , Humanos , Masculino , Desempenho Psicomotor , Inquéritos e Questionários , SuíçaRESUMO
Age-related processes in the neuromuscular and the somatosensory system are responsible for decreases in maximal and explosive force production capacity and deficits in postural control. Thus, the objectives of this study were to investigate the effects of resistance training on strength performance and on postural control in seniors. Forty healthy seniors (67+/-1 yrs) participated in this study. Subjects were randomly assigned to a resistance training (n=20) and a control group (n=20). Resistance training for the lower extremities lasted for 13 weeks at 80% of the one repetition maximum. Pre and post tests included the measurement of maximal isometric leg extension force with special emphasis on the early part of the force-time-curve and the assessment of static (functional reach test) and dynamic (tandem walk test, platform perturbation) postural control. Resistance training resulted in an enhanced strength performance with increases in explosive force exceeding those in maximal strength. Improved performances in the functional reach and in the tandem walk test were observed. Resistance training did not have an effect on the compensation of platform perturbations. Increases in strength performance can primarily be explained by an improved neural drive of the agonist muscles. The inconsistent effect of resistance training on postural control may be explained by heterogeneity of testing methodology or by the incapability of isolated resistance training to improve postural control.
Assuntos
Contração Isométrica/fisiologia , Força Muscular/fisiologia , Treinamento Resistido , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Teste de Esforço/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Equilíbrio Postural/fisiologiaRESUMO
The aging neuromuscular system is affected by structural and functional changes which lead to a general slowing down of neuromuscular performance and an increased risk of falling. The impact of heavy resistance (HR) training in the elderly on maximum voluntary contraction (MVC) and rate of force development (RFD) has been investigated in the past. However, the influence of sensorimotor (SENSO) training and HR training on the ability to compensate for gait perturbations has not yet been investigated in the elderly. Therefore, the purpose of the study was to examine the impact of HR and SENSO training in elderly men on unexpected treadmill perturbations. Functional reflex activity was recorded by means of surface EMG in 40 male subjects (>60 years) before and after 13 weeks of HR and SENSO training and in another 20 male subjects (>60 years), which served as a CONTROL-group. SENSO training resulted in a decrease in onset latency, an enhanced reflex activity in the prime mover as well as a decrease in maximal angular velocity of the ankle joint complex during the perturbation impulses. No significant changes were observed in the HR- and in the CONTROL-group. The results clearly indicate that SENSO training has an impact on spinal motor control mechanisms in the elderly. Training induced improvements in perception and procession of afferent information could be a possible reason for the increase in reflex contraction. Due to these adaptive processes, SENSO training could be a well-suited method for fall preventive programs in elderly people.
Assuntos
Adaptação Fisiológica , Postura/fisiologia , Reflexo/fisiologia , Idoso , Idoso de 80 Anos ou mais , Desaceleração , Eletromiografia , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiologia , Modalidades de Fisioterapia , Análise e Desempenho de Tarefas , Levantamento de PesoRESUMO
BACKGROUND: Muscle strength and speed are important determinants of soccer performance. It has previously been shown that complex training (CT, combination of strength and plyometric exercises within a single training session) is effective to enhance strength and speed performance in athletes. However, it is unresolved whether CT is more effective than conventional strength training that is delivered in one single block (BT) to increase proxies of athletic performance. Thus, the aim of the present study was to investigate the effects of CT versus BT on measures of muscle strength/power, speed, and agility in elite youth soccer players. METHODS: Eighteen male elite youth soccer players conducted six weeks (2 sessions/week, 30 min. each) of progressive CT (n = 10, age: 18.5 ± 2.2 years) or BT (n = 8, age: 18.1 ± 1.6 years) in addition to their regular soccer training (approx. 6 sessions/week, 60-90 min. each). Before and after training, tests were conducted for the assessment of strength (one-repetition maximum [1RM] squat), power (countermovement jump [CMJ]), speed (30-m linear sprint), and agility (T test). Non-parametric analyses were used to calculate differences within (Wilcoxon test) and between (Mann-Whitney-U test) groups. RESULTS: Both CT and BT proved to be safe (i.e. no training-related, but six match-related injuries reported) and feasible (i.e. attendance rate of ≥ 80% in both groups) training regimens when implemented in addition to regular soccer training. The statistical analysis revealed significant improvements from pre-training to post-training tests for the CT group in 1 RM squat (p = 0.043) and CMJ height (p = 0.046). For the BT-group, significantly enhanced sprint times were observed over 5 m (p = 0.039) and 10 m (p = 0.026). Furthermore, both groups significantly improved their t test time (CT: p = 0.046; BT: p = 0.027). However, group comparisons (CT vs. BT) over time (post-training minus pre-training test) did not show any significant differences. CONCLUSION: Six weeks of CT and BT resulted in significant improvements in proxies of athletic performance. Yet CT did not produce any additional effects compared to BT. Future research is needed to examine whether the observed test-specific changes, i.e. improvements in strength/power for the CT-group and improvements in speed for the BT-group, are due to the applied configuration of strength, plyometric, and sprint exercises or if they rather indicate a general training response.
Assuntos
Desempenho Atlético/fisiologia , Força Muscular/fisiologia , Condicionamento Físico Humano/métodos , Aptidão Física/fisiologia , Desempenho Psicomotor/fisiologia , Futebol/fisiologia , Adolescente , Exercício Físico/fisiologia , Humanos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Resultado do TratamentoRESUMO
BACKGROUND: Post-activation potentiation (PAP) can elicit acute performance enhancements in variables of strength, power, and speed. However, it is unresolved whether the frequent integration of PAP eliciting conditioning activities in training (i.âe., complex training) results in long-term adaptations. In this regard, it is of interest to know whether complex training results in larger performance enhancements as compared to more traditional and isolated training regimens (e.âg., resistance training). Thus, this systematic literature review summarises the current state of the art regarding the effects of complex training on measures of strength, power, and speed in recreational, subelite, and elite athletes. Further, it provides information on training volume and intensities that proved to be effective. METHODS: Our literature search included the electronic databases Pubmed, SportDiscus, and Web of Science (1995 to September 2013). In total, 17 studies met the inclusionary criteria for review. Ten studies examined alternating complex training and 7 studies sequenced complex training. RESULTS: Our findings indicated small to large effects for both alternating complex training (countermovement jump height: +â7.4â% [ESdâ=â-0.43]; squat jump height: +â9.8â% [ESdâ=â-0.66]; sprint time: -2.4â% [ESdâ=â0.63]) and sequenced complex training (countermovement jump height: +â6.0â% [ESdâ=â-0.83]; squat jump height: +â11.9â% [ESd â=â-0.97], sprint time: -0.7â% [ESdâ=â0.52]) in measures of power and speed. As compared to more traditional training regimens, alternating and sequenced complex training showed only small effects in measures of strength, power, and speed. A more detailed analysis of alternating complex training revealed larger effects in countermovement jump height in recreational athletes (+â9.7â% [ESdâ=â-0.57]) as compared to subelite and elite athletes (+â2.7â% [ESdâ=â-0.15]). Based on the relevant and currently available literature, missing data (e.âg., time for rest interval) and diverse information regarding training volume and intensity do not allow us to establish evidence-based dose-response relations for complex training. CONCLUSION: Complex training represents an effective training regimen for athletes if the goal is to enhance strength, power, and speed. Studies with high methodological quality have to be conducted in the future to elucidate whether complex training is less, similar, or even more effective compared to more traditional training regimens. Finally, it should be clarified whether alternated and/or sequenced conditioning activities implemented in complex training actually elicit acute PAP effects.
Assuntos
Desempenho Atlético/fisiologia , Desempenho Atlético/estatística & dados numéricos , Força Muscular/fisiologia , Condicionamento Físico Humano/métodos , Condicionamento Físico Humano/estatística & dados numéricos , Aptidão Física/fisiologia , Desempenho Psicomotor/fisiologia , Feminino , Humanos , MasculinoRESUMO
BACKGROUND: Therapeutic climbing exercises are employed for the treatment of shoulder- and knee-joint injuries. However, there is a void in the literature regarding muscle activation levels during the performance of these exercises. Thus, the purpose of this study was to investigate differences in muscle activation during therapeutic climbing exercises depending on the degree of task difficulty. PARTICIPANTS/MATERIAL AND METHODS: A sample of 10 healthy subjects (sex: 4 females, 6 males; age: 27 ± 3 years; climbing experience: 5 ± 3 years) performed three shoulder girdle (i. e., wide shoulder pull, narrow shoulder pull, shoulder row) and two leg extensor (i. e., ascending frontal, ascending sidewards) exercises. Electromyographic (EMG) data were recorded on the right side for eleven muscles and then normalised using the maximum voluntary contractions for each muscle. RESULTS: With increasing task difficulty, muscle activity in all but one muscle (i. e., m. trapezius ascendens) increased significantly for the three shoulder girdle exercises. For the two leg extensor exercises, an increase in task difficulty produced a tendency towards yet not significantly higher muscle activity. CONCLUSION: Shoulder row was the most effective therapeutic climbing exercise in the ability to activate muscles while showing the highest EMG signals. The absence of significant differences in muscle activity between the two leg extensor exercises indicates their equivalent use for muscle activation during therapy.
Assuntos
Terapia por Exercício/métodos , Articulação do Joelho/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Articulação do Ombro/fisiologia , Esportes/fisiologia , Adulto , Feminino , Humanos , MasculinoRESUMO
BACKGROUND: The contractile history of a muscle or a muscle group can result in an acute enhancement of subsequent muscle force output. This phenomenon is referred to as postactivation potentiation (PAP) and it was frequently substantiated in original research manuscripts, systematic literature reviews, and meta-analyses. However, there is a lack in the literature regarding precise dose-response relations. This literature review describes the main determinants of PAP effects and additionally presents the state of the art regarding the acute effects of PAP protocols on measures of strength, power, and speed in subelite and elite athletes of different sport disciplines. Furthermore, an attempt is made to demonstrate evidence-based information concerning the design of effective PAP protocols. METHODS: Our literature search included the electronic databases Pubmed, SportDiscus, and Google Scholar (1995-March 2013). In total, 23 studies met the inclusionary criteria for review. RESULTS: Findings from our literature review indicate that various conditioning activities produce acute PAP effects in subelite and particularly elite athletes. More specifically, conditioning activities that are characterised by multiple sets, moderate to high intensities (60-84 % of the one repetition maximum), and rest intervals of 7-10 min. following the conditioning activity have the potential to induce short-term improvements in muscle force output and sports performance. CONCLUSION: It is recommended that subelite and particularly elite athletes from strength, power, and speed disciplines apply specifically tailored conditioning activities during the acute preparation process for competition to induce performance enhancing PAP effects.