Choice of sprint start performance measure affects the performance-based ranking within a group of sprinters: which is the most appropriate measure?

Sprint start performance has previously been quantified using several different measures. This study aimed to identify whether different measures could influence the performance-based ranking within a group of 12 sprinters, and if so, to identify the most appropriate measure. None of the 10 performance measures ranked all sprinters in the same order; Spearman's rho correlations between different block phase measures ranged from 0.50 to 0.94, and between block phase measures and those obtained beyond block exit from 0.66 to 0.85. Based on the consideration of what each measure quantifies, normalised average horizontal external power was identified as the most appropriate, incorporating both block velocity and the time spent producing this velocity. The accuracy with which these data could be obtained in an externally valid field setting was assessed against force platform criterion data. For an athlete producing 678 +/- 40 W of block power, a carefully set-up manual high-speed video analysis protocol produced systematic and random errors of +5 Wand +/- 24 W, respectively. Since the choice of performance measure could affect the conclusions drawn from a technique analysis, for example the success of an intervention, it is proposed that external power is used to quantify start performance.     

Biological movement variability during the sprint start: performance enhancement or hindrance?

In the current study, we quantified biological movement variability on the start and early acceleration phase of sprinting. Ten male athletes aged 17-23 years (100-m personal best: 10.87 +/- 0.36s) performed four 10-m sprints. Two 250-Hz cameras recorded the sagittal plane action to obtain the two-dimensional kinematics of the block start and initial strides from subsequent manually digitized APAS motion analysis. Infra-red timing lights (80Hz) were used to measure the 10-m sprinting times. The coefficient of variation (CV%) calculation was adjusted to separate biological movement variability (BCV%) from estimates of variability induced by technological error (SEM%) for each individual sprinter and measure. Pearson's product-moment correlation and linear regression analysis were used to establish relationships between measures of BCV% and 10-m sprint start performance (best 10-m time) or 10-m sprint start performance consistency (10-m time BCV%) using SPSS version 12.0. Measurement error markedly inflated traditional measures of movement variability (CV%) by up to 72%. Variability in task outcome measures was considerably lower than that observed in joint rotation velocities. Consistent generation of high horizontal velocity out of the blocks led to more stable and faster starting strides.     

Front- or rear-weighted track start or grab start: which is the best for female swimmers?

The aim of this study was to compare three competitive swimming starts (grab, rear-weighted track, and front-weighted track). The starts were compared in terms of time and instantaneous horizontal velocity, both at take-off from the block and at 5 m from the wall. Twenty US college female swimmers performed three trials of each of the three randomly ordered starts. Swimmers left the block significantly sooner using the front-weighted track start (0.80 s) than the other two starts (both 0.87 s; P < 0.001). In the rear-weighted track start, however, the athletes left the blocks with significantly higher horizontal velocity than in the grab or front-weighted track start (3.99 vs. 3.87 and 3.90 m/s, respectively; each P < 0.001). By 5 m, the front-weighted track start maintained its time advantage over the grab start (2.19 vs. 2.24s; P = 0.008) but not the rear-weighted track start (2.19 vs. 2.21 s; P = 0.336). However, the rear-weighted track start had a significant advantage over the front-weighted track start in terms of instantaneous horizontal velocity at 5 m (2.25 vs. 2.18 m/s; P = 0.009). Therefore, the rear-weighted track start had a better combination of time and velocity than the front-weighted track start. There was also a trend for the rear-weighted track start to have higher velocity at 5 m than the grab start, although this did not reach statistical significance (2.25 vs. 2.20 m/s; P = 0.042). Overall, these results favour the rear-weighted track start for female swimmers even though most of the athletes had little or no prior experience with it. Additional research is needed to determine whether males would respond similarly to females in these three different swimming starts.     

Biological movement variability during the sprint start: Performance enhancement or hindrance?

In the current study, we quantified biological movement variability on the start and early acceleration phase of sprinting. Ten male athletes aged 17–23 years (100-m personal best: 10.87 ± 0.36 s) performed four 10-m sprints. Two 250-Hz cameras recorded the sagittal plane action to obtain the two-dimensional kinematics of the block start and initial strides from subsequent manually digitized APAS motion analysis. Infra-red timing lights (80 Hz) were used to measure the 10-m sprinting times. The coefficient of variation (CV%) calculation was adjusted to separate biological movement variability (BCV%) from estimates of variability induced by technological error (SEM%) for each individual sprinter and measure. Pearson's product–moment correlation and linear regression analysis were used to establish relationships between measures of BCV% and 10-m sprint start performance (best 10-m time) or 10-m sprint start performance consistency (10-m time BCV%) using SPSS version 12.0. Measurement error markedly inflated traditional measures of movement variability (CV%) by up to 72%. Variability in task outcome measures was considerably lower than that observed in joint rotation velocities. Consistent generation of high horizontal velocity out of the blocks led to more stable and faster starting strides.     

Front- or rear-weighted track start or grab start: Which is the best for female swimmers?

The aim of this study was to compare three competitive swimming starts (grab, rear-weighted track, and front-weighted track). The starts were compared in terms of time and instantaneous horizontal velocity, both at take-off from the block and at 5 m from the wall. Twenty US college female swimmers performed three trials of each of the three randomly ordered starts. Swimmers left the block significantly sooner using the front-weighted track start (0.80 s) than the other two starts (both 0.87 s; P < 0.001). In the rear-weighted track start, however, the athletes left the blocks with significantly higher horizontal velocity than in the grab or front-weighted track start (3.99 vs. 3.87 and 3.90 m/s, respectively; each P < 0.001). By 5 m, the front-weighted track start maintained its time advantage over the grab start (2.19 vs. 2.24 s; P = 0.008) but not the rear-weighted track start (2.19 vs. 2.21 s; P = 0.336). However, the rear-weighted track start had a significant advantage over the front-weighted track start in terms of instantaneous horizontal velocity at 5 m (2.25 vs. 2.18 m/s; P = 0.009). Therefore, the rear-weighted track start had a better combination of time and velocity than the front-weighted track start. There was also a trend for the rear-weighted track start to have higher velocity at 5 m than the grab start, although this did not reach statistical significance (2.25 vs. 2.20 m/s; P = 0.042). Overall, these results favour the rear-weighted track start for female swimmers even though most of the athletes had little or no prior experience with it. Additional research is needed to determine whether males would respond similarly to females in these three different swimming starts.     

Hitting a cricket ball: what components of the interceptive action are most linked to expertise?

Differences in interceptive skill between highly skilled and lesser skilled cricket batsmen were examined using a batting task that required participants to strike front-foot drive strokes from a machine-projected ball to a specified target. Task difficulty was manipulated by varying the width of the bat (normal, half, and third width) and target accuracy, and quality of bat-ball contact was monitored along with temporal and sequential elements of the hitting action. Analyses revealed that the highly skilled batsmen were distinguishable from less skilled counterparts by their higher accuracy under the normal and half-width bat conditions, significantly earlier initiation and completion of the front-foot stride, greater synchronization of the completion of the front-foot stride with the commencement of the downswing of the bat, and consistent timing of downswing relative to ball bounce and impact. In keeping with studies of other hitting sports, temporal and spatial coupling of the downswing to ball bounce to help minimize temporo-spatial error at the point of interception appeared critical to skilled performance. Implications for the understanding of interception and for coaching practice are briefly discussed.     

Improvement of darts performance following lucid dream practice depends on the number of distractions while rehearsing within the dream – a sleep laboratory pilot study

In a lucid dream, the dreamer is aware of the dream state and can deliberately practice motor skills. Two field studies indicated that lucid dream practice can improve waking performance in simple motor tasks. The present pilot study investigated the effect of lucid dream practice in a controlled sleep laboratory setting, using a pre-post design with dart throwing in the evening and morning. The experimental group practiced darts in lucid dreams. Because some participants were distracted during lucid dream practice, the group was divided into lucid dreamers with few (n = 4) and many distractions (n = 5). Change of performance was compared to a physical practice group (n = 9) and a control group (n = 9), showing a significant interaction (P = .013, η² = .368). Only the lucid dreamers with few distractions improved (18%) significantly over time (P = .005, d = 3.84). Even though these results have to be considered preliminary, the present study indicates that lucid dream practice can be an effective tool in sports practice if lucid dreamers find ways to minimise distractions during lucid dream practice. Moreover, the study emphasises the necessity to investigate lucid dream practice experiences on a qualitative level.     

Tour de France Champions born or made: where do we take the genetics of performance?

ABSTRACT

Cyclists in the Tour de France are endurance specialists. Twin and family studies have shown that approximately 50% of the variance in a number of performance-related phenotypes (whether measured at baseline, i.e., natural talent, or in response to training) including those important to cycling can be explained by genetic variation. Research into the specific genetic variants that are responsible has identified over 200 genes containing common genetic variants involved in the genetic predisposition to physical performance. However, typically these explain only a small portion of the variance, perhaps 1–2% and collectively they rarely explain anything approaching the 50% of the variance identified in the twin and family studies. Thus, there is a gap in our understanding of the relationship between heritability and performance. This gap may be bridged by investigation of rare variants or epigenetic variation or by altering study designs through increased collaborations to pool existing cohorts together. Initial findings from such efforts show promising results. This mini-review will touch on the genetics and epigenetics of sporting performance, how they relate to cyclists in the Tour de France and where best future efforts may be directed as well as discuss some preliminary research findings.     

Initial identification & selection bias versus the eventual confirmation of talent: evidence for the benefits of a rocky road?

Abstract

The relative age effect (RAE), whereby earlier birthdate children within a selection year are more commonly selected as talented, has been highlighted in the literature. As a consequence, these young athletes get into specialised training earlier and in greater numbers, leading (it is suggested) to a disproportionate opportunity for success. However, this disproportionality seems not to be manifest in senior teams. Accordingly, we examine the identification and conversion rates for academy rugby players, examining a sample of all players passing into and either graduating, or being dismissed from, a major English rugby academy. Data demonstrated a reversal of the RAE “benefit”, whereby late-birth players were less likely to be selected, but more likely to achieve senior professional status. Possible reasons are explored and, on the basis of our data, we propose a psychologically based explanation of greater “growth” due to additional challenge experienced by these initially disadvantaged younger players.     

Unlocking a novel determinant of athletic performance: The role of the gut microbiota,short-chain fatty acids,and “biotics” in exercise

The gut microbiota refers to the collection of trillions of intestinal microorganisms that modulate central aspects of health and disease through influential effects on host physiology. Recently, a connection has been made between the gut microbiota and exercise. Initial investigations demonstrated the beneficial effects of exercise on the gut microbiota, with cross-sectional studies revealing positive correlations between exercise-associated states, and healthy gut microbiota and exercise interventions showed post-intervention increases in the abundance of beneficial bacterial taxa. More recent investigations have focused on exploring the reverse relationship: the influence of the gut microbiota on exercise performance. Murine investigations have revealed that certain bacterial taxa may enhance endurance exercise performance by augmenting various aspects of lactate metabolism. Further, short-chain fatty acids—which modulate metabolism at various organ sites, including within skeletal muscle—have been shown to enhance endurance exercise capacity in mice. This review highlights what is currently known about the connection between the gut microbiota and exercise, with a particular focus on the ergogenic potential of the gut microbiota and how it may be leveraged to enhance endurance exercise performance.     

The "how" and "why" of the ancient Greek long jump with weights: a five-fold symmetric jump in a row?

A plausible explanation for the ancient long jump records from Greek antiquity is sought on the basis of pictorial and written sources, and corroborated with practical tests. Ancient sources report that athletes jumped more than 15 m with weights in their hands, which enabled them to jump further than without these weights. It is proposed that the ancient Greek long jump was a continuous succession of five standing broad jumps, in which the landing phase of one jump was also the countermovement for the next jump. Four trained athletes jumped further with (14.64 +/- 0.76 m, range 13.64-15.63 m) than without weights (13.88 +/- 0.70 m, range 12.60-14.75 m; P = 0.001). These results show that this technique is executable, fits with ancient written and pictorial sources, and allows trained modern athletes to jump distances well over 15 m. The extra distance jumped when using weights may be due to changes in the position of the jumper's centre of mass at take-off and at landing, and an increase in take-off velocity stemming from several biomechanical mechanisms.     

Finding the missing voices of Sport for Development and Peace (SDP): using a ‘Participatory Social Interaction Research’ methodology and anthropological perspectives within African developing countries

Abstract

Whilst the SDP sector has in recent years continued to gain momentum, academic enquiry has largely continued to question its place within development agendas from the outside looking in, examining SDP at the operational and policy levels using methods that advocate the formal guises of research. Through extensive fieldwork experiences in Rwanda and Liberia, the authors propose a form of participatory research methodology for the purpose of empowerment, cultural understanding and insight beyond policy, practice and evaluation. Participatory social interaction research (PSIR) methodology is thus introduced and developed as an approach that looks beyond interventions, deconstructs SDP rhetoric, conceptualizes according to culturally specific contexts and allows narratives and qualitative data to drive theorization and academic discussion. We believe that an embodied, thorough and thoughtful PSIR methodology locates not only diversity within an ill-defined ‘African’ context, but empowers local voices to construct detailed accounts of culture within and outside of SDP.