Gema Torres-Luque

Actigraph GT3X: Validation and Determination of Physical Activity Intensity Cut Points

The aims of this study were: to compare energy expenditure (EE) estimated from the existing GT3X accelerometer equations and EE measured with indirect calorimetry; to define new equations for EE estimation with the GT3X in youth, adults and older people; and to define GT3X vector magnitude (VM) cut points allowing to classify PA intensity in the aforementioned age-groups. The study comprised 31 youth, 31 adults and 35 older people. Participants wore the GT3X (setup: 1-s epoch) over their right hip during 6 conditions of 10-min duration each: resting, treadmill walking/running at 3, 5, 7, and 9 km · h⁻¹, and repeated sit-stands (30 times · min⁻¹). The GT3X proved to be a good tool to predict EE in youth and adults (able to discriminate between the aforementioned conditions), but not in the elderly. We defined the following equations: for all age-groups combined, EE (METs)=2.7406+0.00056 · VM activity counts (counts · min⁻¹)-0.008542 · age (years)-0.01380 ·  body mass (kg); for youth, METs=1.546618+0.000658 · VM activity counts (counts · min⁻¹); for adults, METs=2.8323+0.00054 · VM activity counts (counts · min⁻¹)-0.059123 · body mass (kg)+1.4410 · gender (women=1, men=2); and for the elderly, METs=2.5878+0.00047 · VM activity counts (counts · min⁻¹)-0.6453 · gender (women=1, men=2). Activity counts derived from the VM yielded a more accurate EE estimation than those derived from the Y-axis. The GT3X represents a step forward in triaxial technology estimating EE. However, age-specific equations must be used to ensure the correct use of this device.

Technical variability of the GT3X accelerometer

To analyze the intra- and inter-instrument reliability of the ActiGraph GT3X accelerometer using a vibration table on each orthogonal axis and at five frequencies of motion. Ten GT3X units were subjected to a specific vibration using a motorized vibration table along the vertical, horizontal right-left and horizontal front-back axis, and at 1.1, 2.1, 3.1, 4.1 and 10.2 Hz. The 5 min data for each frequency were analyzed separately for frequency, axis effects, and inter- and intra-instrument variability. We found overall high intra-and inter-instrument reliability for the GT3X accelerometer at frequencies between 2.1 and 4.1 Hz. For frequencies ranging between 2.1 and 4.1 Hz, the intra-instrument coefficient of variation was ≤2.5%. The inter-instrument coefficient of variation ranged widely along axes and frequencies, with the lowest values (≤9%) corresponding to 2.1-4.1 Hz. The intra-class correlation coefficient for activity counts across frequencies and for all axes was 0.97. Overall, our findings support the use of the GT3X accelerometer as an accurate tool to estimate free-living physical activity, at least within those frequencies that are common to most types of human daily activities.

An analysis of competition in young tennis players

Abstract The aim of this study was to analyse the temporal structure of individual tennis play on hard courts in adolescence. Thirty-two national-level tennis players (16 females, 16 males) participated in the study (age 15.6±0.9 years, weight 61.7±1.4 kg, height 1.70±0.14 m). All participants played an official competition on hard courts and with the same type of balls. Games were recorded for later analysis of total play time, real play time, and resting time, both in absolute values and as a percentage of total time. The average duration of a point and the number of strokes per rally were also determined. Results showed no differences based on gender, with a total play time of 105.00±20.00 min, real play time of 31.50±5.83 min, and resting time of 73.5±8.50 min. The ratio of work to resting time was 1:2.7, the number of strokes per rally was 5.12±0.17, and a point lasted an average of 9.08±0.60 s. Our results show the importance of keeping in mind the technical evolution of players at this age, with the goal of reaching maximum athletic performance. The adolescent players showed approximately the same number of strokes per rally, but with a greater average duration compared with adult elite athletes.

Effects of different vibration exercises on bench press.

This study was undertaken to analyze the effects of different vibration recovery strategies via feet or hands on the number of repetitions performed and on mean velocity, peak velocity and blood lactate concentration during consecutive bench-press sets. 9 elite judo athletes performed 3 sets of bench press at 60% of one-repetition maximum (1RM), leading to failure and allowing a 180 s rest period between sets. During the rest period, 1 of the 3 following procedures was performed: 150 s rest plus 30 s push-up vibration exercise (Push-up), 150 s rest plus 30 s squat vibration exercise (Squat) or 180 s only rest (Passive). Statistical analysis revealed that the Squat condition resulted in a significant increase in the number of repetitions achieved, in comparison with all other rest strategies. However, kinematic parameters and blood lactate concentration were not affected by vibration. These data suggest that a vibration stimulus applied to the feet, between sets, can result in positive improvements in upper body resistance exercise performance. Although the mechanisms are not fully understood, this positive effect of vibration could be due to an increased motor cortex excitability and voluntary drive.

Reference values for the sprint performance in male football players aged from 9–35 years

Summary Study aim: The aim of the present study was twofold: firstly, to examine the effect of age on a 20 m sprint performance; and secondly, to establish normative data for the 20 m sprint performance by age in football players. Material and methods: The anthropometric characteristics of 474 football players (aged 16.81 ± 5.35 yrs, range 9.02–35.41 yrs) were examined and their 20 m sprint performance (with 0–10 and 10–20 m splits) was monitored by a photocell system (Brower Timing Systems, Utah, USA). Results: A one-way analysis of variance revealed significant differences between the yearly age groups with regards to the sprint time (p < 0.001, η2 = 0.584), as well as the 0–10 m (p < 0.001, η2 = 0.361) and 10–20 m split times (p < 0.001, η2 = 0.635). The older groups scored better than the younger groups. The time attained in the 20 m sprint, and the 0–10 m and 10–20 m splits correlated moderately to largely with the athlete’s age (r = –0.53, –0.40 and –0.57, respectively, p < 0.001). Conclusions: In summary, the speed ability of the football players improved with age until 15 years old, where it reached its peak. On the other hand, the other age groups U16 to U35 revealed no major differences in the speed over a 20 m sprint. The reference values presented in this study might help football coaches and fitness trainers in monitoring training and in the selection of players. Moreover, since this is the first study of this kind to compare adult age groups, sport scientists focusing on relevant topics might use it as a reference in future studies.

Efectos de un programa de entrenamiento de fuerza sobre la composición corporal y la fuerza máxima en jóvenes entrenados

The aim of this study was to know the adjustments in corporal composition, maximum force and muscular local resistance of a program of training of force in intermittent circuit with overcharges. Method: Eight young males trained in resistance (24,07 ± 3,12 years, 77,96 +7,5 kg, 173 ± 0,2 cm and 14,50 ± 2,00 months of experience) were selected. All the subjects signed an assent in writing of participation in the same one. Characteristic anthropometric, 10 tests of 1RM and one test of muscular local resistance was realized. Later, there was carried out a program of resistance training of 8 weeks of duration by the characteristic of being in intermittent circuit with overcharges, 3 times per week, between 62%72 % of 1RM. A final valuation with the same characteristics of the initial valuation was realized. Results: The results showed a decrease in the percentages of corporal fat of 9,46%, improvements in maximum strength about 3%-31% and an increase in the muscular local resistance of 1,42%. Conclusions: The training in intermittent circuit with overcharges after 8 weeks of duration offers adjustments to level of corporal composition, of maximum strength and muscular local resistance for trained subjects.

Physical and Physiological Characteristics of Judo Athletes: An Update

Judo competition is characterized structurally by weight category, which raises the importance of physiological control training in judo. The aim of the present review was to examine scientific papers on the physiological profile of the judokas, maintenance or loss of weight, framing issues, such as anthropometric parameters (body fat percentage), heart rate responses to training and combat, maximal oxygen uptake, hematological, biological and hormones indicators. The values shown in this review should be used as a reference for the evaluation of physical fitness and the effectiveness of training programs. Hence, this information is expected to contribute to the development of optimal training interventions aiming to achieve maximum athletic performance and to maintain the health of judokas.

Anthropometric characteristics and neuromuscular function in young judo athletes by sex, age and weight category

PurposeThe aim of the study was to examine anthropometric characteristics and neuromuscular function in young judo athletes by sex, age and weight category.Methods146 child and cadet judo athletes were examined for height, body mass (BM), body fat percentage (BF), countermovement jump (CMJ), sit-and-reach (SAR) test and handgrip muscle strength (HMS).ResultsThe results showed that male adolescents were taller, had more HMS, and less BF and flexibility than girls. Significant differences in the sex and weight category were observed, chiefly in BF and body mass index. There were no differences in time to peak force of HMS and CMJ.ConclusionsBased on these findings, special attention should be put to heavy BM categories targeting low BF and high muscle mass, which might contribute to improved neuromuscular function and in turn contribute to the dynamics randori. This study might help profiling the young judoka taking into account sex, age and BM category.

Match analysis of women’s wheelchair tennis matches for the Paralympic Games

The purpose of this study was to determine the differences between winning and losing a wheelchair tennis match in the 2012 Paralympic Games. Data from 67 sets of 32 matches played by 32 female players in the 2012 Paralympic Games were analysed. The variables were grouped into four groups: variables related to the serve, to the return, to winners and errors, and variables related to net points. Univariate (Wilcoxon test) and multivariate (discriminant) analyses of data were carried out to discriminate the result of the set (win or loss). The variables that best predict the result of the set are break points won and points won on the first serve. The results showed that the winning player is a more aggressive server and serve returner, achieves more winning shots than her opponent, and commits fewer errors during the match. The paper discusses the differences between conventional tennis and wheelchair tennis and the application of the results.

Match analysis of elite players during paddle tennis competition

The aim of this study was to determine notational anaylisis structure in paddle tennis in relation to gender. Sixteen semi-final or final paddle tennis matches (8 men and 8 women) of the circuit Paddle Pro Tour were selected. All matches were recorded with a wide-angle camera (Panasonic HC-700; Japan) and were analysed with Kinovea 8.15 software according to Anguera’s method. Match analysis (total time, real time, rest time, work-to-rest-time, points, strokes for points, rally time, and rest rally time) and shots (service, return, ground strokes, net strokes, and indirect strokes) were studied. The results showed statistically significant differences in real time, rest time and number of strokes with higher values in female than in male paddle tennis players (p<.05). A statistical difference was shown in percentage of type of strokes (backhand volley, indirect forehand lob, backhand lob) by gender (p<.05). In conclusion, knowledge of activity patterns within competition helps with specific training for the sport. These findings might help coaches to know better this speciality.