Criterion Validity of Catapult ClearSky T6 Local Positioning System for Measuring Inter-Unit Distance

The validity of a local positioning system (LPS) to measure inter-unit distance was investigated during a team sport movement circuit. Eight recreationally active, female indoor team-sport players completed a circuit, comprising seven types of movements (walk, jog, jump, sprint, 45° change of direction and shuffle), on an indoor court. Participants wore a receiver tag (ClearSky T6, Catapult Sports) and seven reflective markers, to allow for a comparison with the reference system (©Vicon Motion Systems, Oxford Metrics, UK). Inter-unit distance was collected for each combination of participants. Validity was assessed via root mean square error, mean bias and percentage of variance accounted for, both as an overall dataset and split into distance bands. The results presented a mean root mean square error of 0.20 ± 0.05 m, and mean bias detected an overestimation for all distance bands. The LPS shows acceptable accuracy for measuring inter-unit distance, opening up opportunities to utilise player tracking for tactical variables indoors

DIFFERENCES IN KICKING DYNAMICS OF FUTSAL AND SOCCER BALL

Differences in equipment influence the execution of a skill. To date, no literature has identified if ball properties influence foot-ball impact of kicking. The aim of this study was to compare kick impact characteristics of a futsal (FB) and soccer ball (SB). A mechanical limb impacted each ball to standardise all kicking characteristics. High speed video camera (4,000 Hz) captured impact characteristics of each ball. Significant differences (P \u3c 0.05) were observed between the two balls. The SB displayed a higher coefficient of restitution, average force and ball velocity. The timing of key events during impact differed; the FB velocity was higher for the first 75% of impact duration, where it was then exceeded by the SB. The SB was characterised by decreased energy losses, notable during the reformation phase. This work identified that ball properties do influence the impact phase of kicking

Response: Commentary: Long-term Practice with Domain-Specific Task Constraints Influences Perceptual Skills

A Commentary on: Commentary: Long-term Practice with Domain-Specific Task Constraints Influences Perceptual Skills by Yiannaki, C., Carling, C., and Collins, D. (2018). Front. Psychol. 9:1214. doi: 10.3389/fpsyg. 2018.0121

Expertise-related differences in the performance of simple and complex tasks: an event-related potential evaluation of futsal players

Background: In recent years, anecdotal evidence has pointed to the importance of futsal as a significant activity for the development of perceptual and technical skills, possibly due to the intensity of the game providing a multitude of different stimuli to the players. However, no scientific evidence to date exists regarding the processes that may underpin such benefits. The purpose of this study was to assess differences in electro-cortical activity and reaction time (RT) between expert and recreational futsal players. Methods: 11 expert and 12 recreational futsal players (mean age: 28.7 ± 4.9 years) performed congruent and incongruent trials of a modified Flanker task on a customised computer screen. RT generated by an index-finger mouse press was recorded via a customised micro-processing system and electro-cortical activity was recorded by electroencephalography during task performance. Results: There was a significant difference in RT and error rate in congruent and incongruent task performance, and difference in electro-cortical activity showing an enhanced N1 ERP mean amplitude within the parietal region in the expert compared to recreational group. Conclusion: Similar to previous research, a greater level of expertise leads to recruitment of brain areas necessary for the efficient integration and processing of information required to produce desired goal-directed behaviour

Acute high-intensity interval exercise-induced redox signaling is associated with enhanced insulin sensitivity in obese middle-aged men

Background: Obesity and aging are associated with increased oxidative stress, activation of stress and mitogen activated protein kinases (SAPK), and the development of insulin resistance and metabolic disease. In contrast, acute exercise also increases oxidative stress and SAPK signaling, yet is reported to enhance insulin sensitivity and reduce the risk of metabolic disease. This study explored this paradox by investigating the effect of a single session of high-intensity interval-exercise (HIIE) on redox status, muscle SAPK and insulin protein signaling in eleven middle-aged obese men. Methods: Participants completed a 2 h hyperinsulinaemic-euglycaemic clamp at rest, and 60 min after HIIE (4 × 4 mins at 95% HRpeak; 2 min recovery periods), separated by 1–3 weeks. Results: Irrespective of exercise-induced changes to redox status, insulin stimulation both at rest and after HIIE similarly increased plasma superoxide dismutase activity, plasma catalase activity, and skeletal muscle 4-HNE; and significantly decreased plasma TBARS and hydrogen peroxide. The SAPK signaling pathways of p38 MAPK, NF-κB p65, and JNK, and the distal insulin signaling protein AS160Ser588, were activated with insulin stimulation at rest and to a greater extent with insulin stimulation after a prior bout of HIIE. Higher insulin sensitivity after HIIE was associated with higher insulin-stimulated SOD activity, JNK, p38 MAPK and NF-κB phosphorylation (r = 0.63, r = 0.71, r = 0.72, r = 0.71; p < 0.05, respectively). Conclusion: These findings support a role for redox homeostasis and SAPK signaling in insulin-stimulated glucose uptake which may contribute to the enhancement of insulin sensitivity in obese men 3 h after HIIE

Acute exercise alters skeletal muscle mitochondrial respiration and H2O2 emission in response to hyperinsulinemic-euglycemic clamp in middle-aged obese men

Obesity, sedentary lifestyle and aging are associated with mitochondrial dysfunction and impaired insulin sensitivity. Acute exercise increases insulin sensitivity in skeletal muscle; however, whether mitochondria are involved in these processes remains unclear. The aim of this study was to investigate the effects of insulin stimulation at rest and after acute exercise on skeletal muscle mitochondrial respiratory function (JO2) and hydrogen peroxide emission (JH2O2), and the associations with insulin sensitivity in obese, sedentary men. Nine men (means ± SD: 57 ± 6 years; BMI 33 ± 5 kg.m2) underwent hyperinsulinemic-euglycemic clamps in two separate trials 1–3 weeks apart: one under resting conditions, and another 1 hour after high-intensity exercise (4x4 min cycling at 95% HRpeak). Muscle biopsies were obtained at baseline, and pre/post clamp to measure JO2 with high-resolution respirometry and JH2O2 via Amplex UltraRed from permeabilized fibers. Post-exercise, both JO2 and JH2O2 during ADP stimulated state-3/OXPHOS respiration were lower compared to baseline (P<0.05), but not after subsequent insulin stimulation. JH2O2 was lower post-exercise and after subsequent insulin stimulation compared to insulin stimulation in the rest trial during succinate supported state-4/leak respiration (P<0.05). In contrast, JH2O2 increased during complex-I supported leak respiration with insulin after exercise compared with resting conditions (P<0.05). Resting insulin sensitivity and JH2O2 during complex-I leak respiration were positively correlated (r = 0.77, P<0.05). We conclude that in obese, older and sedentary men, acute exercise modifies skeletal muscle mitochondrial respiration and H2O2 emission responses to hyperinsulinemia in a respiratory state-specific manner, which may have implications for metabolic diseases involving insulin resistance

Futsal and Continuous Exercise Induce Similar Changes in Specific Skeletal Muscle Signalling Proteins

Exercise elicits skeletal-muscle adaptations which are important for improved health outcomes. We compared the effects of a futsal game (FUT) and moderate-intensity continuous exercise (MOD), on the skeletal-muscle protein signalling responses in young, healthy individuals. 16 men undertook an incremental exercise test and a resting muscle biopsy performed &gt;48\u2009h apart. They were then randomly allocated to either FUT (n=12) consisting of 2\u2009x\u200920\u2009min halves, or MOD (n=8) consisting of a work-matched running bout performed at an intensity corresponding to the individual ventilatory threshold 1. Work matching was achieved by means of triaxial accelerometers. Immediately after FUT and MOD, participants underwent a second biopsy to assess exercise-induced changes in protein signalling. Total and phosphorylated protein abundance was assessed via western blotting. Both FUT and MOD altered signalling responses in skeletal muscle. FUT increased total ATF2 protein abundance (p=0.048) and phosphorylation (p=0.029), while no changes occurred with MOD. Both exercise regimes increased ACC phosphorylation (p=0.01) and returned a trend for increased p38MAPK phosphorylation. Futsal may be employed as an alternative to continuous exercise to elicit muscle adaptations which may be associated with improved health outcomes. As only FUT increased ATF2 activation, this protein might be a target of future investigation on exercise-induced signalling