Systematically increasing contextual interference is beneficial for learning sport skills

Abstract

To better understand the contextual interference effect, in two experiments we investigated a form of practice schedule that provided novices with systematic increases in contextual interference. This new type of practice schedule was compared with traditional blocked and random scheduling for two types of sports skills. In Experiment 1, we tested the hypothesis that practising variations of the same task with systematic increases in contextual interference would lead to superior performance compared with blocked or random scheduling. Participants practised golf putting tasks following a blocked, random or increasing schedule, which involved initial blocked trials, followed by serial practice trials, and ended with random scheduling. Participants who followed the increasing schedule had superior retention test performance. In Experiment 2, we tested if these learning benefits were observed when learning tasks controlled by different generalized motor programs. Participants practised three different basketball passes (chest, overhead, single arm) in a blocked, random or increasing schedule. Participants practising with gradual increases in contextual interference performed better on retention and transfer tests than participants practising with blocked or random scheduling. The results of these two experiments indicate that a practice schedule offering systematic increases in contextual interference facilitates skill learning.     

Programming Time as a Function of Movement Constraint

Abstract

Although the benefits of exercise are well documented, an international problem of physical inactivity exists. More research, especially theory based, has been recommended. One promising approach for studying exercise behavior is that proposed in the Transtheoretical Model (TTM) of behavior change. This model, however, has received minimal cross-cultural attention and, relative to the current study, measurement instruments have only recently been translated into the Finnish language. The purpose of this study was to assess American and Finnish college students' exercise behaviors on the basis of TTM. Participants were American (n = 169) and Finnish (n = 168) college students who completed language-specific measures of exercise behavior, stage of change, processes of change, decisional balance, self-efficacy, and temptation. The only cultural difference observed was that the American participants rated themselves higher on barrier self-efficacy relative to the Finnish participants. Regardless of nationality or gender, participants classified by their stage of change differed on all the core constructs assessed. These results generally support the utility of TTM for understanding American and Finnish college students' exercise behavior.     

Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.     

资深教练对培养新教练的结构化指导课程的评价：基于自我决定理论的个案研究

探讨资深教练对一个旨在推动和促进新篮球教练员培训质量的结构化指导课程的评价为目的。12 名资深教练（其中 1 名女性教练）受邀参与了本研究,采用自我决定理论设计培养教练员的训练课程项目,采用关注性小组访谈作为资料收集法,让资深教练针对应用自我决定理论的训练课程提出意见。结果显示,此训练课程提供学员一个独特而积极的学习经验。教练员认为,可以通过这个课程获得教练知识并促进技能。本研究结果为今后推广有效的教练培训框架,以及结构化的辅导计划,提高新教练员学习专业知识和提高培训质量提供了新方向。     

Acute cardiovascular responses to interval exercise: A systematic review and meta-analysis

ABSTRACT

Interval exercise training is increasingly recommended to improve health and fitness; however, it is not known if cardiovascular risk is different from continuous exercise protocols. This systematic review with meta-analyses assessed the effect of a single bout of interval exercise on cardiovascular responses that indicate risk of cardiac fibrillation and infarction compared to continuous exercise. Electronic databases Medline, CINAHL, Embase, Scopus and Cochrane were searched. Key inclusion criteria were: (1) intervals of the same intensity and duration followed by a recovery period and (2) reporting at least one of blood pressure, heart rate variability, arterial stiffness or function. Cochrane Risk of Bias tool and GRADE approach were used. Meta-analyses found that systolic blood pressure responses to interval exercise did not differ from responses to continuous exercise immediately (MD 8 mmHg [95% CI ?32, 47], p = 0.71) or at 60 min following exercise (MD 0 mmHg [95% CI ?2, 1], p = 0.79). However, reductions in diastolic blood pressure and flow-mediated dilation with interval exercise were observed 10–15 min post-exercise. The available evidence indicates that interval exercise does not convey higher cardiovascular risk than continuous exercise. Further investigation is required to establish the safety of interval exercise for clinical populations.     

The effect of limb dominance on lower limb functional performance – a systematic review

Lower limb dominance (or lateral preference) could potentially effect functional performance. Clinicians are often asked to make judgements as to when a patient has sufficiently “recovered” from an injury, typically using strength and dynamic performance outcome measures. The primary purpose of this study was to systematically review the literature in relation to limb dominance within active adult populations and discuss some limitations to current methods and relate this to current clinical practice. A search of MEDLINE and CINAHL and EMBASE databases and reference lists of those articles identified was performed. Eleven articles were selected for meta-analysis. There was no statistical effect of limb dominance for any of the functional tests: isokinetic quadriceps and hamstring tests, hamstring:quadriceps ratios, single-leg hop for distance, single-leg vertical jump and vertical ground reaction force following a single-leg vertical jump. Pooled symmetry values varied from 94.6% to 99.6% across the tests, above the clinically accepted benchmark of 90% used in clinical practice. Although the results of this study must be used with discretion, asymmetries in the tasks described in this analysis should be viewed as undesirable and remedied accordingly. Further research is needed to quantify asymmetries, particularly in relation to sport-specific contexts.