The relationship between running distance and coaches' perception of team performance in professional soccer player during multiple seasons.

This study analyzed how the physical movement profile of soccer matches evolved throughout a season by assessing the variability of different metrics depending on the season phase. In addition, the evolution of running distances was investigated in the relation to the team performance based on the coaches' perception. Games from four consecutives Spanish LaLiga seasons (n = 1520) were recorded using an optical tracking system (i.e., ChyronHego). Total distance (TD), distance covered between 14 and 21 km h-1 (MIRD), 21-24 km h-1 (HIRD), and > 24 km h-1 (VHIRD) were analyzed, as well as the number of efforts between 21 and 24 km h-1 (Sp21) and > 24 km h-1 (Sp24). Seasons were divided into four phases (P): P1 (matches 1-10), P2 (11-19), P3 (20-29), and P4 (30-38). Linear mixed models revealed that soccer players covered significantly greater distances and completed a higher number of sprints in P2 and P3. Also, team performance evaluated by soccer coaches was positively related to TD, HIRD, VHIRD and Sp21 in P1. A negative relationship was observed between team performance and distance covered at speeds below 21 km h-1 in P2 and P3. Team performance was negatively related to TD, MIRD, and HIRD, and Sp21 in P4. As conclusion, the team performance perceived by coaches is related to the movement profile throughout a season, and it significantly influences the evolution of soccer players' movement profiles. Specifically, it seems that the players of the best teams have the best physical performance at the beginning of the season with respect to the rest of the phases.

Validity of an ultra-wideband local positioning system to measure locomotion in indoor sports.

The validity of an Ultra-wideband (UWB) positioning system was investigated during linear and change-of-direction (COD) running drills. Six recreationally-active men performed ten repetitions of four activities (walking, jogging, maximal acceleration, and 45º COD) on an indoor court. Activities were repeated twice, in the centre of the court and on the side. Participants wore a receiver tag (Clearsky T6, Catapult Sports) and two reflective markers placed on the tag to allow for comparisons with the criterion system (Vicon). Distance, mean and peak velocity, acceleration, and deceleration were assessed. Validity was assessed via percentage least-square means difference (Clearsky-Vicon) with 90% confidence interval and magnitude-based inference; typical error was expressed as within-subject standard deviation. The mean differences for distance, mean/peak speed, and mean/peak accelerations in the linear drills were in the range of 0.2-12%, with typical errors between 1.2 and 9.3%. Mean and peak deceleration had larger differences and errors between systems. In the COD drill, moderate-to-large differences were detected for the activity performed in the centre of the court, increasing to large/very large on the side. When filtered and smoothed following a similar process, the UWB-based positioning system had acceptable validity, compared to Vicon, to assess movements representative of indoor sports.

Single-fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+-K+-ATPase α- and ß-isoforms in human skeletal muscle.

The Na(+)-K(+)-ATPase (NKA) plays a key role in muscle excitability, but little is known in human skeletal muscle about fiber-type-specific differences in NKA isoform expression or adaptability. A vastus lateralis muscle biopsy was taken in 17 healthy young adults to contrast NKA isoform protein relative abundance between type I and IIa fibers. We further investigated muscle fiber-type-specific NKA adaptability in eight of these adults following 4-wk repeated-sprint exercise (RSE) training, comprising three sets of 5 × 4-s sprints, 3 days/wk. Single fibers were separated, and myosin heavy chain (I and IIa) and NKA (α1-3 and ß1-3) isoform abundance were determined via Western blotting. All six NKA isoforms were expressed in both type I and IIa fibers. No differences between fiber types were found for α1-, α2-, α3-, ß1-, or ß3-isoform abundances. The NKA ß2-isoform was 27% more abundant in type IIa than type I fibers (P < 0.05), with no other fiber-type-specific trends evident. RSE training increased ß1 in type IIa fibers (pretraining 0.70 ± 0.25, posttraining 0.84 ± 0.24 arbitrary units, 42%, P < 0.05). No training effects were found for other NKA isoforms. Thus human skeletal muscle expresses all six NKA isoforms and not in a fiber-type-specific manner; this points to their different functional roles in skeletal muscle cells. Detection of elevated NKA ß1 after RSE training demonstrates the sensitivity of the single-fiber Western blotting technique for fiber-type-specific intervention effects.

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 >48 h apart. They were then randomly allocated to either FUT (n=12) consisting of 2 x 20 min 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.

High-intensity exercise training produces morphological and biochemical changes in adrenal gland of mice.

The effects of training are dependent on complex, adaptive changes which are induced by acute physical exercise at different levels. In particular, evidence shows that the hypothalamus-pituitary-adrenocortical axis, as well as the sympatho-adrenomedullary system, is mainly involved in mediating the physiological effects of physical exercise. The aim of the present study was to investigate, through a morphological and biochemical approach, the effects of training on the adrenal gland of mice, following two different protocols consisting of either low- or high-intensity training. Mice were run daily on a motorised treadmill for 8 weeks, at a velocity corresponding to 60% (low-intensity exercise) or 90% (high-intensity exercise) of the maximal running velocity previously determined by an incremental exercise test. We found that physical exercise produced an increase in the adrenal gland size compared with the control (sedentary) mice. The increase was 31.04% for mice that underwent high-intensity exercise and 10.08% for mice that underwent low intensity exercise, and this appeared to be the result of an increase in the area of both the adrenal cortex and adrenal medulla. Morphological analysis of the adrenal cortex showed that both types of exercise produced an increase in cytoplasmic vacuoles in steroidogenic cells, appearing more abundant after high-intensity exercise. No change was found in the reticulate zone. In the adrenal medulla, despite the absence of morphological changes, immunohistochemistry for tyrosine hydroxylase, dopamine ß-hydroxylase and phenyl-ethanolamine-N-methyltransferase demonstrated an increased immunopositivity for these cathecolamine-synthesizing enzymes after intense exercise. These results were confirmed by immunoblot accompanied by densitometric analysis.

Heart rate and blood lactate evaluation in bouldering elite athletes.

AIM: Bouldering contests consist of a series of short routes, called ''problems'', which shall be climbed without ropes. The purpose of this study was to determine blood lactate [Lac] concentration and heart rate (HR) adaptations both during an official bouldering competition and a simulated contest. METHODS: Eleven Italian elite climbers (6 males, 5 females) were tested from two bouldering national competitions (BNC). [Lac] assessments were done before and 2, 4, 6, 8 min after the contest. On a separate occasion, 9 different elite climbers (6 males, 3 females), matched for anthropometric features and ranking, were assessed in a simulated bouldering contest (SBC), under conditions and difficulties comparable to BNC. HR was measured through the whole performance; [Lac] was assessed before and 3 min after the achievement of each problem. RESULTS: The ascending time in both BNC and SBC was 391+/-85 s and 551+/-96 s (P<0.001), respectively. During SBC the mean HR peak of each problem was 93+/-8% of the subjects' age-predicted maximal HR (HRmax), and HR showed a full recovery after each problem, but in males only. Peak [Lac] after last problem was 6.6+/-1.1 mmol/L and 5.6+/-1.1 mmol/L during BNC and SBC, respectively. A regression analysis showed that temporal changes in [Lac] depend on the attempts duration, with a critical cut-off time of 20 s. CONCLUSIONS: Bouldering contest requires an intense intermittent effort. The high HR may be due to the repeated isometric contractions, particularly of arm and forearm muscles. The net lactate production may depend on the attempts duration.