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Open access

Andrzej Lewandowski, Marcin Kowalewski, Tomasz Kowalik and Zuzanna Piekorz

Abstract

Study aim: The purpose of this study was to investigate changes in the power output and major morphological characteristics during the competition phase. We hypothesised that substantial overloads occurring during this stage cause a decrease in body mass, fat and power output levels in the cyclists.

Material and methods: Nine members from an affiliated Professional Cycling Group ActiveJet Team were observed during the period between January and September. Their mean age was calculated as 25.1 ± 1.6 years. Each month the main somatic fea­tures were determined and the BMI and Rohrer index were measured. The level of adipose tissue was checked using the Tanita BC-418 Ma and the Schoeberer Rad Messtechnik SRM training system was employed to record the maximum level of power output. The following tests were used to collect data: Shapiro-Wilk and ANOVA (assessment of the distribution of variables), Duncan (assessment of the changes of variables), and Pearson correlation coefficient (assessment of power dependence and morphological features). A significance coefficient of α = 0.05 was assumed.

Results: The research of the studied group revealed a steady decrease in the body mass and fat percentage but no significant differences in power output levels. Its peak was reached in the middle of the starting phase (1195.3 ± 222.3 W) and the lowest level was noted during the last month of our observation (1114.1 ± 152.1 W; D = 81.2 W, p = 0.088). Correlations were found between body mass, fat composition and power output levels: moderate for mass (r = 0.383-0.778) and fat (r = 0.352-0.629) content to power output and small negative for height to power output. In most cases, however, they were either weak or low (r = -0.017-0.339).

Conclusions: Significant changes in the morphological characteristics (body weight 70.2 ± 6.4-69.2 ± 5.9 kg, p < 0.001; BMI 21.4 ± 1.9-21.1 ± 1.7, p < 0.001; Rohrer index 1.18 ± 0.11-1.16 ± 0.10, p < 0.001; fat 9.2 ± 3.2-8.2 ± 2.3, p < 0.001) and no differences in power output combined (1151.0 ± 272.4-1114.1 ± 152.1 W, p = 0.434) with medium correlations of these determinants (body height - 2.53-0.354; body weight 0.383-0.778; fat 0.352-0.629) indicate the significance of motor charac­teristics in road racing cyclists. Thus levels in its competency and performance outcomes are determined to a greater extent by factors other than the somatic characteristics.

Open access

Shahrzad Zandi, Reza Rajabi, Mohammadali Mohseni-Bandpei and Hooman Minoonejad

Abstract

Study aim: The aim of this study was to investigate the reliability of the electromyographic activity of selected shoulder girdle muscles during the overhead volleyball throw.

Material and methods: The test-retest reliability of EMG activity of selected shoulder muscles during an overhead volleyball throw was investigated in 15 non-symptomatic university-level female volleyball players for within-day sessions (with a one-hour interval) and between-day sessions (with a one-week interval). Time broadness (a measure of coordination) and root mean square of electromyography signals were obtained. Results: A high within-day (0.85-0.99) and moderate to high between-day (0.68-0.93) intraclass correlation coefficient for normalized RMS activity and a high within-day and between-day intraclass correlation coefficient (0.94 and 0.80; respectively) for time broadness were observed. Absolute agreement of measurements had small values (0.15-1.96). Trends toward higher intraclass correlation coefficient values and lower standard error of measurements, minimum detectable change, mean differ­ences and limits of agreements values were observed for within-day reliability in all test results compared with between-day reliability.

Conclusions: The results suggest that the activity of shoulder muscles can be reliably assessed during the overhead volleyball throw with the described procedure both in the amplitude domain (normalized average root mean square) and the time domain (time broadness of the activities).

Open access

Timothy A. Brusseau and Ryan D. Burns

Summary

Study aim: Two thirds of children are not meeting recommended levels of physical activity. A solution to physical inactivity is Comprehensive School Physical Activity Programming (CSPAP). Little is known regarding the impact of a school’s physical activity leader on CSPAP effectiveness. Therefore, this study explored changes in physical activity accumulated during school hours in CSPAP schools being led by the physical education teacher compared to a stand-alone physical activity leader.

Open access

Tomasz Marciniak, Ida Wiszomirska and Lidia Ilnicka

Abstract

Study aim: Assessment of postural stability performed on an unstable stabilometry platform. Comparison of the results ob­tained by two groups consisting of elderly (OW) (60+ years old) and younger women (YW).Material and methods: Seventy-three female volunteers were divided into two groups: 40 young women (20.2 ± 1.75), and 32 elderly women (68.3 ± 7.43). Participants performed five stability tests on Biodex Balance System SD: three 20-second tries, the Postural Stability Test (PST) and the Fall Risk Test (FRT). Three stability indexes - overall (OSI), anterior-posterior (APSI), and medial-lateral (MLSI) - both with eyes open (EO) and closed (EC) were analyzed. The impact of vision on balance was calculated as EC-EO. Also effect size was calculated and evaluated.Results: All of the parameters differed significantly between groups in favour of YW. The largest difference in significance as well as effect size was noted for FRT, p < 0.001 and 1.86 respectively. Tries measure the impact of vision on balance (EC-EO). The results concerning tries with EC-EO showed the strongest discrimination between groups - OSI p = 0.0088 (relative differ­ence 0.23 ± 0.26) and APSI p = 0.0268 (relative difference 0.17 ± 0.2). YW had a significantly better outcome.Conclusions: YW had better results in all of the parameters taken into consideration, with most of them being significant. This confirms that all of the regressive changes appearing with age influence balance. Lack of visual input (EC) in OW caused sig­nificantly worse results in most of the measured parameters, showing that vision is a very important factor for balance mainte­nance in the elderly.

Open access

Zübeyde Aslankeser and Şükrü Serdar Balcı

Abstract

It is well known that substrate oxidation rates are increased by exercise. The present study had two main objectives: firstly, to examine the effect of a single exhaustive exercise session on post-exercise substrate oxidation and energy expenditure; and secondly, to determine the differences between athletes and non-athletes.

Material and methods: Eighteen healthy male athletes (mean ± SD age; 19.38 ± 2.26 years, VO2max; 60.57 ± 3.90 ml · kg-1 · min-1, n = 8) and non-athletes (age; 20.30 ± 1.26 years, VO2max; 44.97 ± 5.43 ml · kg-1 ·min-1, n = 10) volunteered to participate in the study. After an overnight fast, subjects performed a single sprint exercise session on a cycle ergometer with individual loads (0.075 kg per body weight) until volitional exhaustion. Energy expenditure (EE) and the substrate oxidation rate were measured at rest and during the post-exercise recovery period using indirect calorimetry. Results: Exhaustive exercise significantly increased post-exercise fat oxidation, energy expenditure and contribution of fat to EE (p < 0.05). Also, it significantly decreased post-exercise carbohydrate (CHO) oxidation and the contribution of CHO to EE (p < 0.05). However, the changes in the substrate oxidation rate and EE after the exercise test were not different between the groups (p > 0.05). Conclusions: The study results suggest that a single short-duration exhaustive exercise session causes a higher fat oxidation rate during recovery than at rest, whereas training status did not affect this situation

Open access

K. Petri, N Bandow and K Witte

Abstract

This article discusses the development and application of virtual environments (VEs) in the domain of exercise as well as research in recreational and high-performance sports. A special focus is put on the use of virtual characters (VCs). For its elaboration, the following criteria parameters were chosen: scene content and the role of the VC, output device, kind of additional feedback, level of expertise of the tested participants, kind of user’s movement (reaction), kind of the visualization of the user’s body, kind of study and kind of evaluation. We explored the role of VCs embodying virtual opponents, teammates, or coaches in sports. We divided these VCs in passive and autonomous characters. Passive VCs are not affected by the user, whereas autonomous VCs adapt autonomously to the user’s movements and positions. We identified 44 sport related VEs, thereof 22 each in the domain of recreational sports and high-performance sports: of the identified 44 VEs, 19 VEs are without VC, 20 VEs with passive VCs, and 5 VEs with autonomous VCs. We categorized studies examining expert athletes in high-performance sports as well as studies analyzing novices, beginners or advanced athletes in recreational sports. Nevertheless, all identified systems are suitable for athletes of recreational and high-performance level

Open access

G. Pollard and T. Barnett

Abstract

Recently there has been an interest in developing tennis scoring systems that involve playing a fewer number of points on average. In devising such ‘shorter’ tennis scoring systems, it would be ideal for them to also have the following four characteristics: A smaller standard deviation of duration, a similar value for the probability that the better player wins, an increased efficiency, and a greater average excitement per point played. Thus, in total there are five considerations when devising such new scoring systems. Quite often in this type of study a scoring system that is ‘better’ with regard to one of these characteristics is ‘worse’ with regard to another (or others). In this paper we outline some new tennis scoring systems that have improvements in all (or almost all) of these five characteristics. We identify 3 or 4 different game structures that could be useful for tournaments. A common thread in the approach taken is the elimination of unimportant and unexciting points within the game structure. The choice of which is the most appropriate new format for a particular tournament would depend amongst other things on the planned reduction in the expected set duration

Open access

D. L. Carey, K. Ong, R. Whiteley, K. M. Crossley, J. Crow and M. E. Morris

Abstract

To investigate whether training load monitoring data could be used to predict injuries in elite Australian football players, data were collected from athletes over 3 seasons at an Australian football club. Loads were quantified using GPS devices, accelerometers and player perceived exertion ratings. Absolute and relative training load metrics were calculated for each player each day. Injury prediction models (regularised logistic regression, generalised estimating equations, random forests and support vector machines) were built for non-contact, non-contact time-loss and hamstring specific injuries using the first two seasons of data. Injury predictions were then generated for the third season and evaluated using the area under the receiver operator characteristic (AUC). Predictive performance was only marginally better than chance for models of non-contact and non-contact time-loss injuries (AUC<0.65). The best performing model was a multivariate logistic regression for hamstring injuries (best AUC=0.76). Injury prediction models built using training load data from a single club showed poor ability to predict injuries when tested on previously unseen data, suggesting limited application as a daily decision tool for practitioners. Focusing the modelling approach on specific injury types and increasing the amount of training observations may improve predictive models for injury prevention

Open access

Lucas de Lucena Simões e Silva, Matheus Santos de Souza Fernandes, Eline Autran de Lima, Raul Emídio de Lima and Patrícia Muniz Mendes Freire de Moura

Summary

Study aim: Was to verify whether the regular practice of physical activity promotes some protective factor against the develop­ment of LS in patients infected with hepatitis C virus (HCV). Materials and method: Clinical data were obtained through medical records available at the Pernambuco Liver Institute. Physi­cal activity levels were obtained through the International Physical Activity Questionnaire (IPAQ) short form to classify the patients according to the guidelines of the American College of Sports Medicine (ACSM). Results: The sample consisted of patients of both genders, over 18 years of age, who had positive anti-HCV, HCV-RNA and confirmatory tests for presence or absence of liver steatosis. 126 patients were included in the study. Patients with liver steatosis (G1) were more frequently male (57%) compared to patients without liver steatosis (G2) (p = 0.02). Physical activity analysis showed significant differences for GGT (p = 0.04), HDL (p = 0.04), AF (p = 0.02), viral genotype 3 (p = 0.04) and waist-to-hip ratio (p = 0.01) in anthropometric data. Correlation analysis showed a significant difference for GGT (r = -0.23; p = 0.01) and total bilirubin (BT) (r = -0.22; p = 0.01). Conclusions: Regular practice of physical activity generates a protective factor against the development of LS in patients in­fected by the hepatitis C virus and it is associated with the maintenance of variables related to hepatic and biochemical damage in patients infected with HCV.

Open access

Mohsen Razeghi, Samaneh Ebrahimi, Farzaneh Yazdani and Behdad Tahayori

Abstract

Study aim: There is a lack of evidence to show the presence or absence of a relationship between foot morphology and changes of the force applied to the knee extensor mechanism. The purpose of this study was to examine whether the type of foot is a determining factor in the force applied to the extensor mechanism during walking. Materials and methods: Twenty female subjects (18-30 years), 10 with neutrally aligned feet and 10 with functional flat foot, participated in this study. Data were collected by employing a three dimensional motion capture system and a force platform, while the subjects were walking at their preferred speed. Knee extensor mechanism force was measured at sub-phases of gait (heel strike and toe-off). Results: A significant interaction was found between groups and sub-phases of gait for all the variables tested. The subjects with flat foot exhibited a significantly higher extensor mechanism force at toe-off compared to the control group (p < 0.05). Conclusion: It can be concluded that subtalar hyper-pronation would increase the force applied to the knee extensor mecha­nism at toe-off, through increasing the knee sagittal angle, net external flexion moment and extensor mechanism moment arm. Therefore it may increase the possibility of musculoskeletal injuries