Acute and residual effects of vibratory stimulation on explosive strength in elite and amateur athletes.

Fourteen elite and 14 amateur athletes were subjected to vibratory stimulation during bilateral biceps curl exercises of explosive strength exertion. The athletes performed two separate series of three sets of exercises in random order. The second set of one series was administered with superimposed vibration of 44 Hz and an acceleration of about 30 m x s(-2) transmitted through the two-arms handle to the arm muscles. The mechanical power of each repetition was measured by the 'Power Teach' instrument. The maximal and mean power values for each set were automatically recorded and shown on the screen. The acute effect was evaluated as the difference between the mean and peak power output in the second (with vibratory stimulation) and first (without vibratory stimulation) sets. Similarly, the residual effect was taken to be the difference between the power values of the third (after vibratory stimulation) and the first (before vibratory stimulation) sets. The results were subjected to a repeated-measures analysis of variance with group as a between-participants factor. The results showed that exercise mode (with vs without vibratory stimulation) resulted in a significant immediate effect for mean power and for maximal power. The factor group (elite vs amateurs) resulted in a significant effect for maximal power only. The increase in explosive strength exertion attributed to vibratory stimulation was 30.1 and 29.8 W (10.4% and 10.2%) for maximal and mean power respectively in the elite group, and 20.0 and 25.9 W (7.9% and 10.7%) respectively in the amateur athletes. Vibratory stimulation resulted in an insignificant residual effect.     

Maple syrup urine disease: An uncommon cause for neonatal metabolic distress

Maple Syrup Urine Disease is an autosomal recessive disorder caused by a deficiency in the activity of the branched-chain α-ketoacid dehydrogenase complex. This rare disorder represents one of the causes of acute neonatal illness which results in devastating disturbances of neurological development. On investigation of 1750 infants with neurological impairment for inborn errors of amino acid metabolism, 4 neonates with classical maple syrup urine disease were detected. These otherwise normal neonates presented in the first week after birth with seizures, lethargy and refusal of feeds, hypoglycemia and metabolic acidosis. The plasma and urine concentrations of the branched-chain amino acids were increased and there was ketoaciduria. Two of these neonates expired before specific treatment could be instituted. Routine biochemical screening of neonates with acute illness could unearth many cases of this rare inherited metabolic disease.     

Factors associated with physical activity referral uptake and participation

The aim of this study was to examine participant and scheme characteristics in relation to access, uptake, and participation in a physical activity referral scheme (PARS) using a prospective population-based longitudinal design. Participants (n = 3762) were recruited over a 3-year period. Logistic regression analyses identified the factors associated with the outcomes of referral uptake, participation, and completion (> or = 80% attendance). Participant's age, sex, referral reason, referring health professional, and type of leisure provider were the independent variables. Based on binary logistic regression analysis (n = 2631), only primary referral reason was associated with the PARS coordinator making contact with the participants. In addition to the influence of referral reason, females were also more likely (odds ratio 1.250, 95% confidence interval 1.003-1.559, P = 0.047) to agree to be assigned to a leisure provider. Referral reason and referring health professional were associated with taking up a referral opportunity. Older participants (1.016, 1.010-1.023, P < 0.001) and males were more likely to complete the referral. In conclusion, the PARS format may be less appropriate for those more constrained by time (women, young adults) and those with certain referral reasons (overweight/obesity, mental health conditions). More appropriate targeting at the point of referral could improve participation rates by revealing or addressing barriers that might later result in dropout.     

Sleep management and the performance of eight sailors in the Tour de France à la voile yacht race

We observed how sailors manage their sleep and alertness before and during competition in a long-haul yacht race. Global performance of the teams was also recorded. We assessed eight sailors aged 21-30 years, split into four teams, who competed in the Tour de France à la Voile 2002 yacht race. Two phases of the race were examined: two legs in both the Atlantic Ocean and Mediterranean Sea. Sleep length, sleep debt, and sleepiness before competition and on board during the race were assessed using ambulatory polysomnography. Intermediate and final rankings were considered as a reflection of performance. A significant correlation was observed between the sleep debt before competition and the total sleep time on board during the Atlantic legs. The greater the sleep debt, the more sleepy the participants were. During the Mediterranean legs, almost all the sailors were deprived of sleep and slept during the daytime competitions. We observed that the final ranking in the race related to the sleep management strategy of the participants. In extreme competitive conditions, the effect of a good night's sleep before competition on performance is important. The strategy of the winners was to get sufficient sleep before each leg so as to be the most alert and efficient during the race.     

Physiological responses and time-motion characteristics of various small-sided soccer games in youth players

The aim of this study was to examine acute physiological responses and time-motion characteristics associated with three different small-sided soccer game formats in youth players. Sixteen male soccer players aged 16.3+/-0.6 years (mean+/-s) completed three variations of a small-sided game (i.e. 2 vs. 2, 4 vs. 4, and 6 vs. 6 players) in which heart rate, rating of perceived exertion (RPE), blood lactate concentration, and time-motion characteristics were recorded. The pitch size was altered to keep the relative pitch area per player consistent for each game format. The 2 vs. 2 games exhibited greater blood lactate, heart rate, and RPE responses compared with 4 vs. 4 and 6 vs. 6 games (P<0.05). The players travelled less (P<0.05) distance at speeds of 0-7 km.h(-1) in the 4 vs. 4 compared with the 2 vs. 2 games (1128+/-10 m and 1176+/-8 m, respectively). Average maximal sprint distances above 18 km.h(-1) were lower (P<0.05) in 2 vs. 2 than in 4 vs. 4 and 6 vs. 6 games (11.5+/-3.9 m, 15.3+/-5.5 m, and 19.4+/-5.9 m, respectively), and in 4 vs. 4 compared with 6 vs. 6 games. The results show that as small-sided game formats decrease in size and relative pitch area remains constant, overall physiological and perceptual workload increases.     

First names and popularity in grade school children

The relationship between first name desirability and popularity was studied using 780 boys and 768 girls from six elementary schools. Girls' popularity, as demonstrated by positive sociometric choices, was significantly related to the desirability of their first names. There is also a slight indication that boys' popularity with girls was influenced by the boys' first names. Sociometric rejections were not related to first name desirability for either boys or girls. The findings for girls remained significant when the effects of parental education and ethnicity were partialled out; the single finding for boys did not.     

Sampling period determination for heart rate logging under an exercise regimen

Using a mathematical procedure, we determine appropriate sampling rates for logging heart rate, at a variety of exercise intensities. The mathematical procedure involves correlating exercise and heart rate data to determine a dynamical mathematical model, from which the frequency response of the relationship between exercise intensity and heart rate can be determined. The sampling rate is then straightforwardly deduced by making appropriate measurements on the frequency response curve. We show how careful consideration needs to be given to the choice of dynamical model structure and the work regimen, so that consistent and convincing conclusions can be drawn. We demonstrate that the dynamics of the work-rate/heart-rate system are dependent on the nominal work/heart rate, but a 5-s sampling period, as used in many commercial heart rate monitors, appears to be adequate, especially when some averaging is performed before logging.     

"Show and tell" in the gymnasium revisited: developmental differences in modeling and verbal rehearsal effects on motor skill learning and performance.

Little research has investigated the observational learning process from a developmental perspective. The purpose of this study was to extend previous research by considering two factors: performance versus learning and sequencing versus form scores. Children (N = 60) comprising two age groups (5-0 to 6-11 and 8-0 to 9-11 years) were randomly assigned to verbal rehearsal only, model only, or model plus verbal rehearsal conditions. The task was a 6-part motor skill sequence in which proper sequencing and quality of form were assessed. A 2 x 3 x 4 (age group by model type by trial blocks) repeated measures MANOVA revealed a significant three-way interaction. Older children performed equally well under any of the model type conditions during both performance and learning. For younger children, a model plus rehearsal was superior to rehearsal only on sequence and form at performance and learning and superior to model only on sequence scores during the first two performance trial blocks. Model only and model plus rehearsal conditions were equally effective on form scores. These results suggest that age differences exist in the modeling of motor skills under conditions varying in model type, sequence and form scores, and performance and learning phases.