Yahya Al-Nakeeb

Anthropometric and physiological characteristics of junior elite volleyball players

Objectives: To investigate the anthropometric and physiological characteristics of junior elite volleyball players. Method: Twenty five national level volleyball players (mean (SD) age 17.5 (0.5) years) were assessed on a number of physiological and anthropometric variables. Somatotype was assessed using the Heath-Carter method, body composition (% body fat, % muscle mass) was assessed using surface anthropometry, leg strength was assessed using a leg and back dynamometer, low back and hamstring flexibility was assessed using the sit and reach test, and the vertical jump was used as a measure of lower body power. Maximal oxygen uptake was predicted using the 20 m multistage fitness test. Results: Setters were more ectomorphic (p<0.05) and less mesomorphic (p<0.01) than centres. Mean (SD) of somatotype (endomorphy, mesomorphy, ectomorphy) for setters and centres was 2.6 (0.9), 1.9 (1.1), 5.3 (1.2) and 2.2 (0.8), 3.9 (1.1), 3.6 (0.7) respectively. Hitters had significantly greater low back and hamstring flexibility than opposites. Mean (SD) for sit and reach was 19.3 (8.3) cm for opposites and 37 (10.7) cm for hitters. There were no other significant differences in physiological and anthropometric variables across playing positions (all p>0.05). Conclusion: Setters tend to be endomorphic ectomorphs, hitters and opposites tend to be balanced ectomorphs, whereas centres tend to be ectomorphic mesomorphs. These results indicate the need for sports scientists and conditioning professionals to take the body type of volleyball players into account when designing individualised position specific training programmes.

Body image and physical activity in British secondary school children.

This study assessed the relationship between children’s body image and physical activity and examined any variation in these variables. Two hundred and seventy seven British secondary school children aged 11 to 14 (mean age ± SD = 12.5 ± 0.8 years) participated in this study. Results indicated no significant relationships between body image and physical activity (all p> .05). Boys had higher body esteem scores than girls (p< .01), black children had higher body esteem scores than Asian children (p< .05) and a significant school year by gender interaction (p< .01) indicated that as school year increased body esteem increased in boys but decreased in girls. Boys and high socioeconomic status children also reported greater levels of physical activity than girls and low socioeconomic status children respectively.

Body dissatisfaction, body fat and physical activity in British children

OBJECTIVESnThe present study examined the relationship among body dissatisfaction, body fat and physical activity in British children from different ethnic groups.nnnMETHODSnTwo hundred and seventy-six 11-14 year-old males and females (12.5 +0.8 years) took part in the study. Body dissatisfaction was assessed using a figure rating scale; percent body fat was determined by skinfold measures, and physical activity was assessed using a self-report measure.nnnRESULTSnSignificant, positive relationships were evident between body dissatisfaction and body fat for the whole sample (r = -0.65, p < 0.01). Similar relationships were evident between body dissatisfaction and body fat when split by gender and ethnicity (both p < 0.01). No significant relationships were evident between body dissatisfaction and physical activity (all p > 0.05). ANCOVA controlling for body fat and physical activity revealed that as the covariate of physical activity increased, so did body dissatisfaction (F(1,269) = 13.36, p < 0.01). A significant interaction between fat and ethnicity was also evident (F2,269 = 4.49, p < 0.05). Girls had lower levels of physical activity (F(1,270) = 6.00, p < 0.01); greater body dissatisfaction (F(1,269) = 9.34, p <0.01), and greater fatness (F(1,275) = 37.51, p < 0.01) than boys.nnnCONCLUSIONSnThe majority of children in this study were dissatisfied with their bodies and girls were more dissatisfied than boys. The main novel finding of this study was that the association between body dissatisfaction and body fatness differed across ethnic groups, with this association being greatest in Asian children (Indian, Pakistani and Bangladeshi in origin) in comparison to black and white children.

Body fatness and physical activity levels of young children.

Background: The decline in physical activity levels of young children seems to be combined with a high prevalence of obesity and overweight and a reduction in the participation in organized sport. With the ever-increasing interest in exploring the relationship between physical activity and obesity amongst children, it is important to provide a more precise estimate of both physical activity and body fatness. A significant proportion of previous research on this topic has relied on self-report methods to assess physical activity and body mass index as a proxy for actual body fatness. There is a need to investigate the relationships between physical activity and fatness in children using objective methods. Aim: This study was conducted in order to explore the relationship between physical activity patterns and percentage body fat amongst a group of primary school children. Subjects and methods: Forty-seven primary school children (boys, nu2009=u200923; girls, nu2009=u200924) participated in this study. They were randomly selected from children in years 5 and 6 (9–11 year olds) of four schools drawn from the same catchment area in the city of Birmingham, UK. The frequency, intensity and duration of physical activity were determined using continuous heart rate monitoring from 8:30 am to 8:30u2009pm over three separate days (two weekdays and one weekend day). Percentage body fat was assessed using air displacement plethysmography. Results: Results indicated that 52% of children did not achieve a single 15-min bout of sustained moderate physical activity over the three days of monitoring. Independent t-tests revealed that girls were significantly fatter (t44u2009=u2009−3.126, pu2009=u20090.003) than boys. There was no significant difference (t45u2009=u20090.225, pu2009>u20090.05) between boys and girls in accumulated time spent with heart rates above the moderate physical activity threshold. Pearsons product moment correlation coefficients revealed no significant (ru2009=u2009−0.017, pu2009>u20090.05) relationship between per cent body fat and average daily time spent in moderate and vigorous activity. Conclusion: Despite the prediction to the contrary, there was no evidence of a significant relationship between percentage body fat of children and time spent in moderate and vigorous activity. Additionally, while there were no significant gender differences in physical activity patterns, children were more physically active during weekdays than weekends.

Perceived Exertion is Related to Muscle Activity During Leg Extension Exercise

This study examined the relationship between ratings of perceived exertion and muscle activity during dynamic leg extension exercise using a resistance exercise specific OMNI-RPE scale. Twenty volunteers (10 males, 10 females, age 22.2 ± 3.1 yr) performed one set of leg extension exercise at 30%, 60%, and 90% of their one-repetition maximum (1-RM). OMNI-RPE responses were assessed for both the active muscle (OMNI-AM) and the overall body (OMNI-O) following each intensity. Electromyography (EMG) data were collected from the rectus femoris, vastus lateralis, and vastus medialis muscles. A two-factor repeated measures ANOVA showed a significant OMNI-RPE (region) X intensity interaction (p < 0.01). Both OMNI-AM and OMNI-O increased with exercise intensity, and RPE-AM was higher than RPE-O at all intensities. EMG activity increased with exercise intensity in all muscle groups (all p < 0.01). Muscle activity was significantly and positively related to OMNI-RPE in both the active muscle and overall body (all p < 0.01). The OMNI-Res RPE scale may be a promising technique for regulating resistance training intensity.

The Impact of the Built Environment on Young People's Physical Activity Patterns: A Suburban-Rural Comparison Using GPS

The built environment in which young people live has a significant influence on their physical activity (PA). However, little is known regarding how youth from suburban and rural settings utilise their surrounding environments to participate in free-living PA. 50 adolescents aged 13–14 years old (22 rural; 28 suburban) wore an integrated GPS and heart rate device during non-school hours and completed a daily PA diary over 7 days. Descriptive statistics and analyses of variance were used to explore differences in the amount and location of moderate-to-vigorous physical activity (MVPA) between genders and youth from different geographical settings. Suburban youth participated in significantly (p = 0.004) more daily PA (52.14 minutes MVPA) and were more extensive in their utilisation of their surroundings, compared to rural youth (26.61 minutes MVPA). Suburban youth visited more public recreational facilities and spent significantly more time outdoors and on local streets (109.71 minutes and 44.62 minutes, respectively) compared to rural youth (55.98 minutes and 17.15 minutes, respectively) during weekdays. Rural youth on average spent significantly more time within the home (350.69 minutes) during weekends compared to suburban youth (214.82 minutes). Rural females were the least active group of adolescents, participating in the least amount of daily PA (20.14 minutes MVPA) and spending the least amount of time outdoors (31.37 minutes) during weekdays. Time spent outdoors was positively associated with PA. The findings highlight the disparity in PA levels and the utilisation of the surrounding built environment between youth from two different geographical settings and possible environmental causes are discussed. The study supports the use of GPS (combined with other methods) in investigating geographical differences in young people’s PA and movement patterns. This method provides a wealth of information that may assist future policies and interventions in identifying environmental characteristics that promote PA in youth from different geographical settings.

The relationship between pedometer-determined physical activity, body mass index and lean body mass index in children

OBJECTIVEnTo cross-sectionally assess weekend to weekday variation of physical activity in British children and to consider the role of Body Mass Index (BMI, W/H(2)) and Lean Body Mass Index (LBMI, H(2)/W) when examining this issue.nnnMETHODSnA total of 496 children aged 8-14 years, were measured for height and weight and the activity levels were analysed using pedometers to measure mean step counts for 4 consecutive days (2 weekdays, 2 weekend days).nnnRESULTSnBoys had significantly lower BMI than girls. Higher values for average weekend steps were associated with lower BMI values. BMI values were; however, found to be positively skewed but when the analysis was repeated using LBMI, data was normally distributed and the conclusions remained the same.nnnCONCLUSIONSnWeekday steps are higher than weekend steps for children irrespective of gender or weight status. Mean steps taken during weekend days are significantly associated with reduced BMI in children. These findings may be questioned because BMI is highly skewed and not normally distributed. However, LBMI provides a suitable alternative that is normally distributed and can be used to compare the relationship between weight status and physical activity.

Relationship between body image and percent body fat among British school children.

The aim of the study was to examine the relationship between body image and percent body fat in British school children. A total of 223 11- to 14-yr.-old children from central England took part in the study. Body image was measured using a self-report questionnaire, and percent body fat was measured using skinfold indices. Analysis indicated that body image and adiposity were significantly (p <.01) related for the whole sample, for boys and girls and for White children, Black children, and Asian children. An analysis of variance further indicated significant differences in body image and adiposity between boys and girls, with boys having a more positive body image and a lower percent body fat. Differences (p <.05) were also evident between Black and Asian children, with Black children having a more positive body image and lower percent body fat. No differences were evident between Black and White children or Asian and White children.

Influence of Familiarization on a Backward, Overhead Medicine Ball Explosive Power Test

This study examined the influence of familiarization with the backward, overhead medicine ball throw test of explosive power. Male rugby players (N = 28) aged 15 to 16 (M ± SD = 15.1 ± 0.5) years completed the medicine ball throw six times. Repeated measures ANOVA indicated that the distance thrown differed across trials (F5,135 = 12.83, p < 0.01). Least significant differences post hoc multiple comparisons revealed significant differences between a number of trials; however, no significant difference was evident between the fifth and sixth trials (Mdiff = .005, p > 0.05). Typical error of measurement became less as trials progressed, with the typical error of measurement being 0.10 m between the fifth and sixth trials indicating little within subject variation between medicine ball throws following a familiarization period. The backward, overhead medicine ball throw may be a practical, reliable method to assess total body, explosive power of male teen-aged rugby players; however, completion of at least 5 to 6 practice trials is suggested for participants to obtain a stable score.

Differences in Body Fat of British Children from Various Ethnic Groups

This study assessed the percent body fatness of British secondary school children and examined any variation in fatness according to school year, gender and ethnicity. 782 children aged 11 to 14 participated in the study. Body fatness was assessed using skinfold measures and obesity was classified using child-specific cut-off points. Results from 2 3 3 ways ANOVA indicated that approximately 25 to 30 percent of children were classified as obese. Significant differences were evident in body fatness according to gender (p<.01) and ethnicity (p<.01). Boys were leaner than girls and black children were leaner than white and Asian children (both p<.01). Furthermore a significant gender ethnicity interaction (p<0.01) was found. Both white and black boys had significantly lower percent body fat compared to white and black girls but Asian boys had similar percent body fat to Asian girls. The body fatness of British secondary school children may therefore be a cause for concern.