Estimation of body density based on hydrostatic weighing without head submersion in young Japanese adults

Abstract

The aim of this study was to evaluate the effect of a soccer-training season on the anthropometric and performance characteristics of elite youth soccer players.

Two groups (age: 14.4 years) participated in this study: 1) 24 soccer players training 8 to 10 hours per week and 2) 26 non-athletic boys used as controls. Anthropometric measurements, aerobic (Yo-Yo Intermittent Recovery test level 1) and anaerobic (counter-movement-jump (CMJ), squat-jump (SqJ), five-jump-test (5JT), and speed (T5m, 10 m, 30 m)) performances were assessed twice during 8 months (T0: October; T1: May) of the competitive season.

Data showed significant differences in height and weight at T0 between the two groups (P < 0.05), while no difference in the percentage of body fat (%BF) was observed. However, the soccer players were significantly taller and had lower %BF than age-matched controls at T1.

Compared to the controls, the soccer players attained better results in the physical fitness test (P < 0.05) at T0 and T1 except in (T5m) sprinting speed. Hence, significant improvements (P < 0.05) in physical parameters were observed between T0 and T1 only in soccer players.

The results demonstrate that soccer-training season was able to provide maturation free improvement in anthropometric and performance characteristics in young soccer players during the training season.     

A Sport Education Fitness Season’s Impact on Students’ Fitness Levels,Knowledge, and In-Class Physical Activity

Purpose: The purpose of this study was to determine the extent to which a sport education season of fitness could provide students with recommended levels of in-class moderate-to-vigorous physical activity (MVPA) while also increasing students’ fitness knowledge and fitness achievement. Method: One hundred and sixty-six 5th-grade students (76 boys, 90 girls) participated in a 20-lesson season called “CrossFit Challenge” during a 4-week period. The Progressive Aerobic Cardiovascular Endurance Run, push-ups, and curl-ups tests of the FITNESSGRAM® were used to assess fitness at pretest and posttest, while fitness knowledge was assessed through a validated, grade-appropriate test of health-related fitness knowledge (HRF). Physical activity was measured with Actigraph GT3X triaxial accelerometers. Results: Results indicated a significant time effect for all fitness tests and the knowledge test. Across the entire season, the students spent an average of 54.5% of lesson time engaged in MVPA, irrespective of the type of lesson (instruction, free practice, or competition). Conclusions: The results suggest that configuring the key principles of sport education within a unit of fitness is an efficient model for providing students with the opportunity to improve fitness skill and HRF knowledge while attaining recommended levels of MVPA.     

Training load and submaximal heart rate testing throughout a competitive period in a top-level male football team

ABSTRACT

The aim of this study was to investigate training load and cardiorespiratory fitness in a top-level Spanish (LaLiga) football team (n = 17). The submaximal Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1_SUB) was performed in four moments of the competitive period from early February (E1) to early May (E4). Training load was quantified using a 10-Hz global positioning system and heart rate (HR) recording (n = 837 individual training sessions), while match load was quantified using semi-automated cameras (n = 216 individual match observations). Cardiorespiratory fitness moderately improved as the season progressed (P < 0.05; effect sizes = 0.8 to 1.2). Cumulative total distance covered during training between E1 and E4 was negatively correlated with percentage of changes in mean HR during the last 30 s of Yo-Yo IR1_SUB (P = 0.049; r = ?0.47 [?0.71; ?0.14]; moderate). HR during the last 30 s of Yo-Yo IR1_SUB was negatively correlated to total distance covered during the match (P = 0.024; r = ?0.56 [?0.80; ?0.17]; moderate). Yo-Yo IR_SUB can be used to monitor seasonal changes in cardiorespiratory fitness without the need to have players work until exhaustion. Cardiorespiratory fitness given by mean HR during the last 30 s of the test seems meaningful in relation to match performance.     

A modified TRIMP to quantify the in-season training load of team sport players

Abstract

The aims of the study were to modify the training impulse (TRIMP) method of quantifying training load for use with intermittent team sports, and to examine the relationship between this modified TRIMP (TRIMP_MOD) and changes in the physiological profile of team sport players during a competitive season. Eight male field hockey players, participating in the English Premier Division, took part in the study (mean±s: age 26±4 years, body mass 80.8±5.2 kg, stature 1.82±0.04 m). Participants performed three treadmill exercise tests at the start of the competitive season and mid-season: a submaximal test to establish the treadmill speed at a blood lactate concentration of 4 mmol · l^?1; a maximal incremental test to determine maximal oxygen uptake ([Vdot]O_2max) and peak running speed; and an all-out constant-load test to determine time to exhaustion. Heart rate was recorded during all training sessions and match-play, from which TRIMP_MOD was calculated. Mean weekly TRIMP_MOD was correlated with the change in [Vdot]O_2max and treadmill speed at a blood lactate concentration of 4 mmol · l^?1 from the start of to mid-season (P<0.05). The results suggest that TRIMP_MOD is a means of quantifying training load in team sports and can be used to prescribe training for the maintenance or improvement of aerobic fitness during the competitive season.     

Acceleration and sprint profiles of a professional elite football team in match play

Abstract

The aim of this study was to characterise the acceleration and sprint profiles of elite football match play in one Norwegian elite football team (Rosenborg FC). Fifteen professional players in five playing positions took part in the study (n = 101 observations). Player movement was recorded during every domestic home game of one full season (n = 15) by an automatic tracking system based on microwave technology. Each player performed 91 ± 21 accelerations per match, with a lower number in the second compared with the first half (47 ± 12 vs. 44 ± 12). Players in lateral positions accelerated more often compared to players in central positions (98.3 ± 20.5 vs. 85.3 ± 19.5, p < 0.05). Average sprint distance was 213 ± 111 m distributed between 16.6 ± 7.9 sprints, with no differences between first (106 ± 60 m, 8.2 ± 4.2 sprints) and second halves (107 ± 72 m, 8.3 ± 4.8 sprints). Players in lateral positions sprinted longer distances (287 ± 211 m vs. 160 ± 76 m, p < 0.05) and tended to sprint more often (21.6 ± 7.8 vs. 13.0 ± 5.7, p = 0.064) compared to players in central positions. We found more walking and less of the more intense activities during the last third of the season compared to the first. The main finding in this study was that Norwegian elite players had substantially less number of accelerations and fewer but longer sprints than previous studies reported for higher-ranked leagues. Also, less high-intensity activity was found towards the end of the season. Ultimately, these data provide useful information for the fitness coach (1) in planning of position-specific football training and (2) to avoid the decline in high-intensity activities the last third of the competitive season.     

Interaction of sedentary behaviour,sports participation and fitness with weight status in elementary school children

Abstract

Even though the effect of single components contributing to weight gain in children have been addressed only limited research is available on the combined association of sports participation, physical fitness and time spent watching TV with body weight in children. Baseline data from 1594 children (809 male; 785 female), 7.1±0.6 years of age participating in a large school-based intervention in southern Germany was used. Height and weight was measured and body mass index (BMI) percentiles (BMIPCT) were determined accordingly. Sports participation and time spent watching TV was assessed via parent questionnaire while fitness was determined via a composite fitness test. Combined and single associations of sports participation, TV time and fitness with BMIPCT and weight status were assessed via ANCOVA as well as logistic regression analysis, controlling for age and sex. A significant interaction of TV time, sports participation and fitness on BMIPCT occurred, despite low correlations among the three components. Further, there was a combined association of sports participation and TV time on BMIPCT. TV time and fitness were also independently associated with BMIPCT. Similarly, only increased TV time and lower fitness were associated with a higher odds ratio for overweight/obesity. These results underline the complex interaction of TV time, sports participation and fitness with BMIPCT. In children, TV time and fitness have a stronger influence on BMIPCT compared to sports participation. Sports participation, however, may not reflect overall activity levels of children appropriately. More research is necessary to examine the complex interaction of various behaviours and fitness with BMIPCT.     

Epidemiology of injuries in First Division Spanish football

Abstract

The aim was to examine the injuries sustained by Spanish football players in the First Division and to compare injury-related variables in the context of both competition and training. The injury data were prospectively collected from 16 teams (427 players) using a specific web-based survey during the 2008/2009 season. A total of 1293 injuries were identified (145 were recurring injuries). The overall injury incidence was 5.65 injuries per 1000 h of exposure. Injuries were much more common during competition than during training (43.53 vs. 3.55 injuries per 1000 h of exposure, P < 0.05). Most of the injuries (89.6%) involved the lower extremities, and overuse (65.7%) was the main cause. Muscle and tendon injuries were the most common types of injury (53.8%) among the players. The incidence of training injuries was greater during the pre-season and tended to decrease throughout the season, while the incidence of competition injuries increased throughout the season (all P < 0.05). In conclusion, the results of this study suggest the need for injury prevention protocols in the First Division of the Spanish Football League to reduce the number of overuse injuries in the muscles and tendons in the lower extremities. In addition, special attention should be paid during the pre-season and the competitive phase II (the last four months of the season) in order to prevent training and competition injuries, respectively.     

Relationships between training load,injury, and fitness in sub-elite collision sport athletes

Abstract

The purpose of this study was to develop statistical models that estimate the influence of training load on training injury and physical fitness in collision sport athletes. The incidence of training injuries was studied in 183 rugby league players over two competitive seasons. Participants were assessed for height, body mass, skinfold thickness, vertical jump, 10-m, 20-m and 40-m sprint time, agility, and estimated maximal aerobic power in the off-season, pre-season, mid-season, and end-season. Training load and injury data were summarised into pre-season, early-competition, and late-competition training phases. Individual training load, fitness, and injury data were modelled using a logistic regression model with a binomial distribution and logit link function, while team training load and injury data were modelled using a linear regression model. While physical fitness improved with training, there was no association (P = 0.16 – 0.99) between training load and changes in physical fitness during any of the training phases. However, increases in training load during the early-competition training phase decreased (P = 0.04) agility performance. A relationship (P = 0.01 – 0.04) was observed between the log of training load and odds of injury during each training phase, resulting in a 1.50 – 2.85 increase in the odds of injury for each arbitrary unit increase in training load. Furthermore, during the pre-season training phase there was a relationship (P = 0.01) between training load and injury incidence within the training load range of 155 and 590 arbitrary units. During the early and late-competition training phases, increases in training load of 175 – 620 arbitrary units and 145 – 410 arbitrary units, respectively, resulted in no further increase in injury incidence. These findings demonstrate that increases in training load, particularly during the pre-season training phase, increase the odds of injury in collision sport athletes. However, while increases in training load from 175 to 620 arbitrary units during the early-competition training phase result in no further increase in injury incidence, marked reductions in agility performances can occur. These findings suggest that reductions in training load during the early-competition training phase can reduce the odds of injury without compromising agility performances in collision sport athletes.     

Changes in body composition and physique of elite university-level female swimmers during a competitive season

Changes in the body composition of a sample of elite university-level female swimmers were monitored at three points during a competitive season, October, December and March. Body composition was estimated via densitometry and a series of anthropometric dimensions was taken at each occasion. Body weight, absolute and relative fatness, all six skinfolds and the calf circumference decreased, while density and lean body mass increased significantly during the period of intensive training between October and December. Changes during the second half of the season were smaller. Weight and relative fatness increased, while body density and the triceps skinfold decreased significantly between December and March. Hence, the major changes in body composition associated with swim training occurred during the early part of the season when training was intense. Most of the changes were maintained during the second half of the season. Correlations between body composition at the start of training and changes after approximately 10 and 24 weeks were negative and generally significant. Changes in anthropometric somatotype estimates with swim training were minor and occurred primarily in the first and third components.     

Relationship between weight status and cognition in children: A mediation analysis of physical fitness components

ABSTRACT

Cross-sectional study aimed to analyse differences in cognitive performance across fitness components categories (cardiorespiratory fitness [CRF], speed-agility and muscular fitness [MF]) and weight status in children, and to determine whether physical fitness mediates the association between body mass index (BMI) and cognitive performance. Fitness components and BMI were measured using standard procedures in 630 children aged 5-to-7 years from the provinces of Cuenca and Ciudad Real, Spain. BADyG was used to assess cognitive performance. We used ANCOVA models to test mean differences in cognition scores by BMI and fitness categories. Hayes’s PROCESS macro was used for mediation analyses. Children with normal weight scored better in spatial factor and general intelligence than their overweight/obese peers (p < 0.05), but differences were attenuated when controlling for CRF (p > 0.05). Children with better results in CRF and speed-agility scored better in all cognitive dimensions even after controlling for BMI (p < 0.05). Similarly, children with high MF obtained better scores in verbal factor (p < 0.05). All fitness components acted as mediators of the relationship between BMI and general intelligence (p < 0.05). These findings highlight the crucial role of fitness in minimising the negative effect of excess weight on children’s cognition.

Abbreviations: BMI: Body mass index; CRF: Cardiorespiratory fitness; MF: Muscular fitness; BADyG E1: Battery of general and differential aptitudes; SES: Socioeconomic status; SD: Standard deviation; IE: Indirect effect     

A Comparative Study of Physique and Performance Measures Resulting from a Short-Term Physical Fitness Course

Abstract

Cardiorespiratory and anthropometric assessments were made on 95 randomly selected young college males enrolled in three physical fitness sections and one tennis course, each lasting eight weeks. Laboratory and field measures were utilized to report and evaluate changes in functional fitness and physique variables, including nine selected fat and girth measurements, height and weight, timed vital capacity, Harvard Step Test, grip strength, mile run time, and vertical jump. Analysis of the data yielded the following conclusions: (a) Eight weeks of physical fitness training can produce significant improvements in physique and circulorespiratory characteristics; (b) A skill-oriented tennis class demonstrates no significant physical improvements; (c) Body weight can be increased while body fat is lost; (d) Vital capacity has little value in reflecting levels of physical performance; (e) Specificity of a physical fitness program will influence its outcome.     

10 weeks of heavy strength training improves performance-related measurements in elite cyclists

ABSTRACT

Elite cyclists have often a limited period of time available during their short preparation phase to focus on development of maximal strength; therefore, the purpose of the present study was to investigate the effect of 10-week heavy strength training on lean lower-body mass, leg strength, determinants of cycling performance and cycling performance in elite cyclists. Twelve cyclists performed heavy strength training and normal endurance training (E&S) while 8 other cyclists performed normal endurance training only (E). Following the intervention period E&S had a larger increase in maximal isometric half squat, mean power output during a 30-s Wingate sprint (P < 0.05) and a tendency towards larger improvement in power output at 4 mmol ? L^?1 [la^?] than E (P = 0.068). There were no significant difference between E&S and E in changes in 40-min all-out trial (4 ± 6% vs. ?1 ± 6%, respectively, P = 0.13). These beneficial effects may encourage elite cyclists to perform heavy strength training and the short period of only 10 weeks should make it executable even in the compressed training and competition schedule of elite cyclists.     

Low-dose exercise training does not influence cardiac autonomic control in healthy sedentary men aged 55 – 75 years

Abstract

The purpose of this study was to evaluate the effects of a realistic, feasible, and commonly used fitness training programme on cardiac autonomic control in 14 sedentary men aged 62.0 ± 6.1 years (mean ± s). All participants performed a one-year fitness training programme in which training intensity and frequency were specifically chosen to be compliant for the majority of the participants (2 – 3 sessions per week at moderate intensity). At the same time, a reference group consisting of 15 sedentary age-matched men (age 64.2 ± 6.5 years) did not change their habitual physical activity. Measurements were performed before and after the training intervention. Cardiac autonomic control was inferred from resting values (supine and standing) of heart rate variability (HRV) computed in the frequency domain over 10-min intervals. Endurance capacity was evaluated during a maximal incremental bicycle ergometer test. In spite of an increase in peak oxygen consumption ([Vdot]O_2peak) by 6.4% after training, heart rate in the training group remained unchanged at rest and at the same metabolic demand. No changes in resting parameters of HRV were shown for either groups or positions. Results from this study provide no evidence of a clinically meaningful increase in the vagal modulation to the sinus node at rest after one year of low-volume and moderate-intensity fitness training in men aged 55 – 75 years.     

Monitoring biological and psychological measures throughout an entire season in male handball players

Abstract

The aim of this study was to monitor biological markers of inflammation and oxidative stress, mood states, and recovery-stress states throughout an entire season in male handball players. Fourteen handball players (age 20.1±2.5 years) with a regular training and competitive background in handball (11.0±3.7 years) from the same club volunteered to participate. All participants completed 40 weeks of training. The training load was increased progressively throughout the season. Blood samples were collected and questionnaires were administered during preparatory, competitive, and recovery periods. Blood C-reactive protein and oxidized glutathione (GSSG) concentrations increased during periods of high load, while the reduced/oxidized glutathione ratio (GSH/GSSG) decreased. These changes were accompanied by a significant increase in total leukocyte count. Positive correlations were found between C-reactive protein, GSSG, GSH/GSSG ratio, and training load. No changes were observed in the Total Mood Disturbance score of the Profile of Mood States (POMS). However, scores on some Recovery-Stress Questionnaire for Athletes subscales, such as Injury, Physical Recovery, and Being in Shape, correlated with training load. Findings indicate that during periods of high training load, handball players developed a low grade of inflammation and oxidative state. Results support the usefulness of monitoring psychological and biological markers of inflammation, oxidative stress, and training load during season.     

Psychological Mood Profiles of Sighted and Unsighted Beep Baseball Players

Purpose: Decline of motor performance in older individuals affects their quality of life. Understanding the contribution of sport-related training in advanced ages might help to attenuate motor performance decay as one gets older. The purpose of our study was to evaluate the extent to which long-lasting training in running or sport-specific skills during old age preserves motor performance in different motor tasks. Method: Older runners and tennis players with at least 10 years of training were assessed as were age-matched and young exercisers. Performance was evaluated for 6 motor tasks requiring different functions of sensorimotor control expected to decline with aging. Results: Analysis revealed that runners had increased aerobic fitness in comparison with the other older participants and that they presented similar performance to older exercisers in the motor tasks. Tennis players outperformed the other groups of older participants on coincident timing and simple reaction time and achieved similar performance to the young group on the timing task. Conclusions: These results suggest selective maintenance of task-specific processing through extensive practice of tennis-related motor skills in older adults.     

Erythrocyte Changes during Training in High School Women Cross-Country Runners

Abstract

Indices of red blood cell (RBC) status were assessed in eight high school women cross-country runners (experimental group) six times during a competitive season (Weeks 0, 1, 2, 4, 6, and 8) and three times (Weeks 0, 1, and 3) in 11 high school women who were not runners (comparison group). The only significant preseason hematological difference between the groups was a higher RBC fragility for the runners. All blood indices for both groups were within normal ranges throughout the study. During the competitive season (Weeks 0–8), the runners had a significant increase in [Vdot]O₂ max (ml/kg · min^?1) of 7.6% and a significant decrease in post step-test heart rate (13.4%) but showed no changes in body weight, height, or percent body fat. At Week 3, the comparison group showed an increase (0.9%) in body weight, but no changes were observed in the other anthropometric variables or post step-test heart rate. During the competitive season, the runners had significant changes in all blood variables except reticulocyte count; these changes were most marked during the first week of the season when there were significant decreases in hemoglobin (Hb) concentration (8.0%), hematocrit (Hct) (7.7%), RBC count (6.8%), and osmotic fragility (21.5% and 42.0% in 5.95 and 6.80 mM NaCl solutions, respectively) and a significant increase in mean RBC volume (1.8%). In contrast, the only significant change in blood indices of the comparison group was a decrease (1.9%) in mean RBC volume at the end of Week 1. Changes in blood variables of the runners appeared to be transient, in that values at Week 8 were comparable to those at preseason except for mean RBC volume. Although blood volume changes could be responsible for some of the blood variable changes in the runners, the results support increased RBC destruction rather than hemodilution as a cause of the RBC changes in the runners, and suggest a possible stress on body iron reserves for increased erythropoiesis during recovery from those changes.     

Comparison of Physical Fitness Scores of White and Black Seventh Grade Boys of Similar Socioeconomic Level

Abstract

Boys (N = 115) in the seventh grade of a junior high school were tested for physical fitness by the AAHPER Youth Fitness Test. In addition, data were collected for age, height, weight, and socioeconomic level of each boy. Two racial groups were formed consisting of 30 white and 30 black students who were matched on age and socioeconomic level. The purpose of this study was to determine whether the physical fitness of white and black students of equal socioeconomic level was significantly different. There were no significant differences between the groups in age, height, weight, and socioeconomic level. The black students exceeded the white students significantly on the shuttle run, 50-yd. dash, 600-yd. run and composite fitness score. It was concluded that black male students of similar socioeconomic level to white students in the seventh grade, have a higher level of physical fitness.     

Monitoring of immunological parameters in adolescent basketball athletes during and after a sports season

Abstract

The objective of the present study was to monitor the immunological and hormonal responses and the occurrence of upper respiratory symptoms in adolescent basketball athletes during the different stages of a sports season. Anthropometric measures, biochemical analyses (interleukin-6, interleukin-10, tumour necrosis factor-alpha, C-reactive protein, testosterone and cortisol), neuromuscular evaluations (standing vertical jumping ability, agility and estimated VO_2max) and leukocyte counts were performed at four moments: 72 h before the season (?72 h); before the season (Pre-season); after six weeks, at the end of the preparatory period (Preparatory); and after 20 weeks, at the end of the competitive period (Competitive). Also, the occurrence of upper respiratory symptoms was collected weekly during all stages of the season. There were significant increases in monocytes, cortisol, tumour necrosis factor-alpha and C-reactive protein at the Competitive moment as compared to the Pre-season. In addition, interleukin-10 decreased at the Competitive moment as compared to the Pre-season. Occurrence of upper respiratory symptoms demonstrated increases (38%) during the competitive period as compared to the preparatory. These results suggest that periods of training and competition could increase the occurrence of upper respiratory symptoms in adolescent athletes and this may be due to the unwanted effects of an inflammatory process in response to the excessive stress of training and competition.     

Ground Reaction Force Symmetry during Walking and Running

Abstract

The purpose of this study was to determine the effect of triathlon training using multiple, short cycle-run sequences (multicycle-run training) on cycle-run performance. Twelve competitive triathletes, randomized into two groups, underwent multicycle-run training or normal training for 6 weeks. During this period, baseline training remained the same for both groups, and only the high-intensity component differed. The differentiated exercises were performed at or above 100% maximal aerobic velocity. The improvements in overall cycle-run performance were similar (3.3 ± 1.4 % and 6.1 ± 1.7 % rise in performance in multicycle-run and normal training, respectively). However, the improvement in performance was significantly greater for the multicycle-run training (- 11.2 ± 6.8 s versus ?1.2 ± 7.7 s for multicycle-run training and normal training, respectively) during both the cycle-run change and the first 333-m lap, which together are termed the cycle-run transition. We concluded that 6 weeks of multicycle-run training did not induce greater improvement in cycle-run performance than did normal training in competitive triathletes. However, it did induce significant improvement in the cycle-run transition. This finding indicates that multicycle-run training may help competitive triathletes to develop greater skill and better physiological adaptations during this critical transition period of the triathlon race.