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Purpose: Domain and sub-domain physical self-perceptions have been associated with adolescent moderate intensity physical activity although the association with different types of adolescent moderate intensity physical activity remains unclear. This study seeks to examine the relationship between personal self-perceptions and adolescent sport/exercise and lifestyle moderate intensity physical activity frequency. Design/methodology/approach: A total of 122, 13-to-14 year-old, English adolescents from Leeds, West Yorkshire (58 boys and 64 girls) had their personal self-perceptions, sport/exercise and lifestyle moderate intensity physical activity assessed. Findings: No significant positive relationships were found between boys' personal self-perceptions and lifestyle moderate intensity physical activity. However, a range of weak (r = 0.34-0.42 but significant relationships (p less than 0.01) were found between personal self-perceptions and boys' sport/exercise frequency. In contrast, only perceptions of strength competence were significantly related to girls' sport/exercise frequencies (r = 0.28; p less than 0.05), while all personal self-perceptions scales were significantly related to girls' lifestyle moderate intensity physical activity (r = 0.26-0.32; p less than 0.05). Research limitations/implications: The use of correlation analyses by this study placed limitations on the extent to which cause-effect relationships were established. Furthermore, girls' sport/exercise was poorly distributed, which may have led to the non-significant relationship found between this activity type and personal self-perceptions. The presence of a significant relationship between these two variables should therefore not be discounted. Originality/value: This study seems to be the first to investigate and identify variations in the personal self-perceptions--moderate intensity physical activity relationship relative to activity type. Although more research is required, findings have implications for practitioners aiming to tailor physical activity interventions to this group and researchers aiming to match specific correlates to different types of adolescent physical activity. (Contains 1 figure and 4 tables.)

The purpose of the study was to examine the effect of creatine (Cr) supplementation on anaerobic performance when ingesting creatine and carbohydrates (CHO) together. Twenty male physical education students comprised the two experimental (CR and CRCHO) and one control (CON) groups of the study. All groups performed three 30 s anaerobic Wingate tests (AWTs) interspersed with 6 minutes of recovery. The CR group (n = 7) ingested 5 g of Cr 5 times per day for 4 days. Subjects in the CRCHO group (n = 6) ingested the same quantity but additionally after each 5 g dose of Cr consumed 500 ml of a commercially available energy drink containing 100 g of simple sugars. Over all three AWTs average mean power improved significantly compared to baseline for the CR group (5.51%) but not for the CRCHO group (3.06%). Mean power for the second AWT was improved following the acute loading for the CR group only (4.54%) and for the third AWT for both CR (8.49%) and CRCHO (5.75%) groups. Over all three AWTs a significant change was recorded in average peak power following the acute loading for the CR group (8.26%) but not for the CRCHO group (4.11 %). Peak power was significantly improved following the loading only for the CR group during the third AWT (19.79%). No changes in AWT performance were recorded for the CON group after intervention. The findings of the present study suggest that ingesting creatine together with carbohydrates will not further improve performance compared to the ingestion of creatine only. [ABSTRACT FROM AUTHOR]

The use of global positioning systems (GPS) technology within referees of any sport is limited. Therefore, the purpose of the current study was to evaluate the movement and physiological demands of professional rugby league referees using GPS tracking analysis. Time-motion analysis was undertaken on 8 referees using 5-Hz GPS devices and heart rate monitors throughout a series of Super League matches. 44 data sets were obtained with results identifying similar total distance covered between first and second half periods with a significant ( P = 0.004) reduction in the number of high velocity efforts performed between 5.51-7.0 m.s -1 (1 st = 21 ± 8, 2 nd = 18 ± 8). Mean distance covered from greatest to least distance, was 3 717 ± 432 m, 3 009 ± 402 m, 1 411 ± 231 m, 395 ± 133 m and 120 ± 97 m for the following 5 absolute velocity classifications, respectively; 0.51-2.0 m.s -1 ; 2.1-4.0 m.s -11 : 4.01- 5.5 m.s -1 ; 5.51-7.0 m.s -1 ; < 7.01 m.s -1 . Heart rate was significantly ( P < 0.001) greater in the first (85.5 ± 3.4 % maxHR) compared to the second (82.9 ± 3.8 % maxHR) half. This highlights the intermittent nature of rugby league refereeing, consisting of low velocity activity interspersed with high velocity efforts and frequent changes of velocity. Training should incorporate interval training interspersing high velocity efforts of varying distances with low velocity activity while trying to achieve average heart rates of ~ 84 % maxHR to replicate the physiological demands. [ABSTRACT FROM AUTHOR]

This study assessed the reproducibility of performance and selected metabolic variables during a variable high-intensity endurance cycling test. 8 trained male cyclists (age: 35.9 ± 7.7 years, maximal oxygen uptake: 54.3 ± 3.9 mL·kg-1·min-1 ) completed 4 high-intensity cycling tests, performed in consecutive weeks. The protocol comprised: 20 min of progressive incremental exercise, where the power output was increased by 5 % maximal workload (Wmax) every 5 min from 70 % Wmax to 85 % Wmax; ten 90 s bouts at 90 % Wmax, separated by 180 s at 55 % Wmax; 90 % Wmax until volitional exhaustion. Blood samples were drawn and heart rate was monitored throughout the protocol. There was no significant order effect between trials for time to exhaustion (mean: 4113.0 ± 60.8 s) or total distance covered (mean: 46126.2 ± 1968.7 m). Total time to exhaustion and total distance covered showed very high reliability with a mean coefficient of variation (CV) of 1.6 % (95 % Confidence Intervals (CI) 0.0 ± 124.3 s) and CV of 2.2 % (95 % CI 0.0 ± 1904.9 m), respectively. Variability in plasma glucose concentrations across the time points was very small (CV 0.46-4.3 %, mean 95 % CI 0.0 ± 0.33 to 0.0 ± 0.94 mmol·L-1 ). Plasma lactate concentrations showed no test order effect. The reliability of performance and metabolic variables makes this protocol a valid test to evaluate nutritional interventions in endurance cycling. [ABSTRACT FROM AUTHOR]

Objectives: To examine the validity of body composition estimates obtained using foot-to-foot bio-electrical impedance analysis (BIA) in overweight and obese children by comparison to a reference four-compartment model (4-CM). Subjects/Methods: 38 males: age (mean ± sd) 13.6 ± 1.3 years, body mass index 30.3 ± 6.0 kg.m-2 and 14 females: age 14.7 ± 2.2 years, body mass index 32.4 ± 5.7 kg.m-2 participated in the study. Estimates of fat-free mass (FFM), fat mass (FM) and percentage body fat (PBF) obtained using a Tanita model TBF-310 and a 4-CM (derived from body mass, body volume, total body water and total body bone mineral measurements) were compared using bias and 95% limits of agreement (Tanita minus 4-CM estimates). Results: Body composition estimates obtained with the Tanita TBF-310 were not significantly different from 4-CM assessments: for all subjects combined the bias was -0.7kg for FM, 0.7kg for FFM and -1.3% for PBF. However, the 95% limits of agreement were substantial for individual children: males, up to ±9.3kg for FFM and FM and ±11.0% for PBF; females, up to ±5.5kg for FFM and FM and ±6.5% for PBF. Conclusions: The Tanita TBF-310 foot-to-foot BIA body composition analyser with the manufacturer's prediction equations is not recommended for application to individual children who are overweight and obese although it may be of use for obtaining group mean values. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To assess the long-term effects of a multidisciplinary approach involving structured fun-type skill learning physical activities in the treatment of obese and overweight children. DESIGN: A longitudinal investigation incorporating repeated measurements before and after the 8 week intervention and after the 44 week follow-up period. METHODS: The camp programme (Massachusetts, USA) utilised structured fun-based skill learning physical activities, moderate dietary restriction and behaviour modification. The primary aims of the intervention were to reduce body mass and promote the maintenance of the reduction in body mass using an alternative to standard exercise prescription. SUBJECTS: One-hundred and ninety-four children (64 boys and 130 girls, aged 12.6±2.5 y) enrolled at a summer weight loss camp, of which 102 children (38 boys and 64 girls aged 13.6±2.4 y) returned 1 y later. MEASUREMENTS: On commencement of the programme all children were assessed for body mass and stature. At follow-up, data was available on 102 subjects for body mass and stature. RESULTS: Over the 8 week intervention significant reductions (P=0.00) in body mass were obtained. During the 44 week follow-up significant increases (P=0.00) were noted in body mass, body mass index (BMI) and stature, but as expected there were large variations in the responses. One year after the initial measures had been taken mean body mass and BMI were lower than at the start of the intervention, BMI significantly so (week 0, 32.9 ± 7.4 kg/m²; week 8 29.1 ± 6.5 kg/m²; week 52, 30.05 ± 7.04 kg/m²); (P=0.00). Stature increased significantly (week 0, 1.58 ± 0.12 m; week 52, 1.64±0.11 m) (P=0.00) during this period, demonstrating a reduction in mean body mass over a I y period whilst subjects continued to increase in stature. When changes in BMI are analysed with the use of standard scores, there is a non-significant increase (P=0.07) in BMI... [ABSTRACT FROM AUTHOR]

Reports on the enhanced development of bone mass during the growing years of artistic gymnasts. Importance of early involvement in high weight-bearing physical activities in promoting bone health in childhood; Comparison of the bone density of several artistic gymnasts; Demonstration of a greater volumetric lumbar spinal density, arm and total-body bone-mineral density.

Objective: The purpose of this study was to examine the prevalence of obesity over time in the same individuals comparing body mass index (BMI), waist circumference (WC) and waist to height ratio (WHtR). Study design: Five year longitudinal repeated measures study (2005 2010). Children were aged 11-12 (Y7) years at baseline and measurements were repeated at age 13-14 (Y9) years and 15-16 (Y11) years. Methods: WC and BMI measurements were carried out by the same person over the five years and raw values were expressed as standard deviation scores (sBMI and sWC) against the growth reference used for British children. Results: Mean sWC measurements were higher than mean sBMI measurements for both sexes and at all assessment occasions and sWC measurements were consistently high in girls compared to boys. Y7 sWC - 0.792 [95% confidence interval (CI) 0.675-0.908], Y9 sWC = 0.818 (95%CI 0.709-0.928), Y11 sWC = 0.943 (95%CI 0.827-1.06) for boys; Y7 sWC = 0.843 (0.697-0.989), Y9 sWC = 1.52 (95%CI 1.38-0.67), Y11 sWC = 1.89 (95%CI 1.79-2.04) for girls. Y7 sBMI = 0.445 (95%CI 0.315-0.575), Y9 sBMI = 0.314 (95%CI 0.189-0.438), Y11 sBMI = 0.196 (95%CI 0.054-0.337) for boys; Y7 sBMI 0.353 (0.227-0.479),Y9 sBMI = 0.343 (95% CI 0.208-0.478), Y11 sBMI - 0.256 (95%CI 0.102-0.409) for girls. The estimated prevalence of obesity defined by BMI decreased in boys (18%, 12% and 10% in Y 7, 9 and 11 respectively) and girls (14%, 15% and 11% in Y 7, 9 and 11). In contrast, the prevalence estimated by WC increased sharply (boys; 13%, 19% and 23%; gifts, 20%, 46% and 60%). Conclusion: Central adiposity, measured by WC is increasing alongside a stabilization in BMI. Children appear to be getting fatter and the additional adiposity is being stored centrally which is not detected by BMI. These substantial increases in WC are a serious concern, especially in girls. [ABSTRACT FROM AUTHOR]

Aim: The aim of the present study was to assess the validity of jump height (h), absolute (VPOWERABS) and relative to body mass (VPOWERREL) performance indices when elicited of a modified 30 s Bosco vertical jump test (VJT) based on the absolute (WPOWERABS) and relative (WPOWERREL) power values of a 30 s Wingate test (WAnT)., Methods: Nineteen physical education students with mean ± SD age 21 ± 3 y, body mass 73.8 ± 7 kg and height 1.8 ± 0.06 m performed a 30 s VJT on a force plate and a 30 s WAnT on a Monark cycle ergometer. Performance data were expressed in W and W.kg-1 of body mass for WPOWERABS and WPOWERREL; in cm, W and W.kg-1 for h, VPOWERABS and VPOWERREL, respectively. The performance indices' values were expressed as means and SDs of the 30 s duration of both tests, as well as in 4 time intervals of 7.5 s (0-7.5 s, 7.5-15 s, 15-22.5 s, and 22.5-30 s)., Results: WPOWERABS and h were significantly (P<0.05) correlated in the 4 time intervals (0-7.5 s: r=0.51; 7.5-15 s: r=0.36; 15-22.5 s: r=0.39) and in the overall duration of the test (0-30 s: r=0.38). Significant correlation was also revealed between VPOWERABS and WPOWERABS, but only for the interval 0-7.5 s (r=0.48)., Conclusion: A 30 s VJT is valid against a 30 s WAnT only when h is used as performance indices. The selection of the appropriate unit of measurement is important for assessing effort distribution in maximum effort tests of short duration.

Strategies that enhance the acquisition of bone mass may be protective against osteoporosis. BMD was compared in 20 artistic gymnasts (10 boys; 10 girls) and 20 untrained children ages 7-8 years. Higher regional values of BMD were observed in female gymnasts than untrained girls. If retained to adulthood, this higher BMD may protect skeletal integrity in later life. Strategies that enhance the acquisition of bone mass in children may assist with the prevention of osteoporosis. This study explored the effects of regular high-impact and weight-bearing activity before the age of 7 years on total and regional bone mineral density (BMD). Twenty artistic gymnasts (10 boys and 10 girls) and 20 untrained children, 7-8 years of age, were recruited. The untrained children were matched to gymnasts by sex, height, weight, and age. Female gymnasts trained 8-10 h per week and had trained regularly for 3-4 years. Male gymnasts trained 4-6 h per week and had trained for 1-2 years. Measurements of bone mineral density were made using DXA for total body BMD (TBBMD); lumbar spine, both areal (aSBMD) and volumetric (vSBMD); total spine; pelvis; arms; and legs. Significant mean differences (8-10%) in aSBMD, vSBMD, arm BMD, and TBBMD were observed between female gymnasts and untrained girls (p < 0.05: aSBMD, vSBMD, and TBBMD body mass (BM); p < 0.01: arm BMD). A nonsignificant trend toward a higher TBBMD/BM and arm BMD was observed in male gymnasts compared with untrained boys. Trends toward a higher BMD within the pelvis, legs, and total spine were also observed in gymnasts. There were no differences in total and regional BMD between untrained boys and untrained girls. The results suggest that gymnastics training before the age of 7 years enhances the acquisition of bone mass at selected skeletal sites. The magnitude of this enhancement seems to be linked to the cumulative volume of such training. If retained during adolescence and young adulthood, a surfeit of bone acquired through high-impact and weight-bearing activity in early childhood may protect skeletal integrity in later life.

The aim of this study was to identify the kinematic and postural characteristics associated with sprint running on uphill and downhill slopes of 3 degrees and on a horizontal surface. Eight male physical education students were filmed while sprinting maximally on an uphill-downhill platform under each of three conditions: (a) uphill at 3 degrees, (b) downhill at 3 degrees and (c) horizontal. Running speed, step rate, step length, step time, contact time, flight time and selected postural characteristics of the step cycle were analysed. Running speed was 9.2% faster (P < 0.05) during downhill and 3.0% slower (P < 0.05) during uphill compared with horizontal sprint running. During downhill and uphill sprint running, step length was the main contributor to the observed changes in running speed. It increased by 7.1% (P < 0.05) for downhill sprint running and was associated with significant changes in posture at touchdown and take-off. During uphill sprint running, step length decreased by 5.2% (P < 0.05), which was associated with significant changes in posture and reduced flight distance. Given the interaction between the acute changes in step length and posture when sprinting on a sloping surface, our findings suggest that such changes in posture may detract from the specificity of training on such surfaces. The chronic effects of training on such slopes on the kinematics and posture of horizontal sprint running are currently unclear.

Purpose: The relationship of both physical activity and predicted maximum oxygen consumption (VO2max) with the clustering of metabolic risk factors associated with the metabolic syndrome (MS) was examined within 711 employed middle-aged (46.9 +/- 7.8 yr) men., Methods: Metabolic markers included fasting glucose, triglycerides, high-density lipoprotein cholesterol, blood pressure, and BMI, defined by highest risk quintiles or clinically relevant risk thresholds., Results: The prevalence and age-adjusted odds ratios of all MS clusters were inversely graded across both higher physical activity index (PAI) and cardiorespiratory fitness (CRF) categories. The age-adjusted odds ratio for the clustering of clinically relevant metabolic markers was 0.60 (95% CI 0.22-1.22) for subjects in the occasional/light PAI, 0.32 (95% CI 0.12-0.82) for the moderate/moderately vigorous PAI, and 0.13 (95% CI 0.02-1.02) for the vigorous PAI when compared with subjects in the sedentary PAI (P < 0.05 for trend). The corresponding age-adjusted odds ratio was 0.28 (95% CI 0.14-0.57) for subjects in the moderate fitness category and 0.12 (95% CI 0.05-0.32) for the highest fitness category compared with those in the lowest fitness category (P < 0.001 for trend). Higher levels of physical activity or CRF were also associated with significantly lower age-adjusted odds ratios for the MS after exclusion of obesity in the MS definition., Conclusion: Overall, these cross-sectional results suggest that higher physical activity and predicted VO2max levels are associated with a decreased clustering of risk factors associated with the MS in middle-aged men of higher social class.

Purpose: The relationship of both leisure time physical activity and predicted maximum oxygen consumption (VO2max) with plasma fibrinogen concentration was examined within a cohort of employed middle-aged men., Methods: Analyses were performed on a subsample of 635 nonsmoking men (46.7 +/- 7.7 yr) who completed a preventive medical assessment between 1992 and 1996., Results: Among nonsmokers, mean age-adjusted fibrinogen concentration decreased significantly with higher physical activity index (PAL) categories and quartiles of predicted VO2max (mL x kg(-1) x min(-1)) (both P = 0.001). Mean age-adjusted plasma fibrinogen concentrations were significantly different (P < 0.05) between inactive and vigorous PAI groups and extreme quartiles of predicted VO2max (mL x kg(-1) x min(-1)). These relationships were no longer significant after adjustment for the confounding effect of other ischemic heart disease risk factors. Stepwise multiple regression analyses showed that age, sum of skinfolds, and blood leukocyte count were the strongest predictors of plasma fibrinogen concentration., Conclusion: These data do not confirm a significant independent association of both physical activity and predicted VO2max (mL x kg(-1) x min(-1)) with fibrinogen concentrations among nonsmoking middle-aged men of similar high social class.

Purpose: The relationship of both self-reported leisure time physical activity (LTPA) and predicted maximum oxygen consumption (VO2max) with plasma viscosity and hematocrit (Hct) concentration was examined within a cross-sectional sample of employed middle-aged men., Methods: Analyses were performed on a subsample of nonsmoking men who completed a preventive medical assessment between 1992-1996., Results: Among nonsmokers the mean age-adjusted levels of plasma viscosity (N = 590) and Hct concentration (N = 632) were significantly lower with higher Physical Activity Index (PAI) categories (P = 0.001 and P = 0.01, respectively). Following adjustment for conventional IHD risk factors and blood leukocyte count, a significant inverse relationship remained for Hct (P = 0.044) but not plasma viscosity. Mean age-adjusted plasma viscosity and Hct concentration also showed a significant decrease with higher quartiles of predicted VO2max (mL x kg(-1) x min(-1))(P = < 0.00005 and P = 0.0004, respectively). Following adjustment for all confounding variables mean plasma viscosity and Hct concentration remained significantly lower with higher quartiles of predicted VO2max (mL x kg(-1) x min(-1))(P = < 0.00005 and P = 0.047)., Conclusions: These data confirm the inverse relationship between LTPA and/or predicted VO2max with plasma viscosity and Hct concentration within nonsmoking middle-aged men of high socioeconomic status.

We investigated the effect of an acute creatine loading (25 g per day for 4 days) and longer-term creatine supplementation (5 g of creatine or 5 g of placebo per day for 2 months) on the performance of 22 elite swimmers during maximal interval sessions. After the acute creatine loading, the mean of the average interval swim times for all swimmers (n = 22) improved (44.3+/-16.5 s before vs. 43.7+/-16.3 s after supplementation; P<0.01). Three of the 22 swimmers did not respond positively to supplementation. After 2 months of longer-term creatine supplementation or placebo, neither group showed a significant change in swimming performance (38.7+/-13.5 s before vs. 38.7+/-14.1 s after for the creatine group; 48.7+/-18.0 s before vs. 48.7+/-18.1 s after for the placebo group). We conclude that, in elite swimmers, 4 days of acute creatine loading improves swimming performance significantly when assessed by maximal interval sessions. However, longer-term supplementation for 2 months (5 g of creatine per day) did not benefit significantly the creatine group compared with the placebo group.

Purpose: Evidence shows that those with a learning disability are typically amongst the most inactive and sedentary members of the population, yet few studies have focused on the determinants of physical activity. The aim of the present study was to establish whether a group of 24 adults with mild and moderate learning disabilities receive adequate support to be able to make choices to lead a physically active lifestyle., Method: A descriptive study was used based on interviews with 24 adults with learning disabilities (mean age of 34 years) triangulated by day time and residential care workers. Participants volunteered from two residential homes and one social education centre (SEC) in a city in the North of England., Results: The participants face a set of primary barriers that prevent them from having a choice to adopt the Department of Health's recommendations for physical activity. Identified barriers included: unclear policy guidelines in residential and day service provision together with resourcing, transport and staffing constraints; participant income and expenditure; and limited options for physically active community leisure., Conclusions: These are barriers that are widely acknowledged and understood by day and residential staff and participants in the study, but are arguably poorly understood by policy makers, health promotion agencies, commissioners and providers of learning disability services. The current lack of resources and inadequately specified responsibilities associated with community care deny many people with learning disabilities real choices to live a physically active healthy lifestyle.

Purpose: Whilst the health benefits associated with regular physical activity are well known, little objective evidence exists regarding the activity profiles of adults with mild and moderate learning disabilities. The aims of the present study were to establish 7 day physical activity profiles for 24 adults with mild and moderate learning disabilities and to compare them with the general population and current Department of Health recommendations for physical activity., Method: A descriptive study was used, based on interviews with 24 adults with learning disabilities (mean age 34 years) triangulated by daytime and residential care workers. Participants volunteered from two residential homes and one social education centre (SEC) in a city in the North of England., Results: The physical activity profiles show that the participants led sedentary lifestyles that were more exaggerated than those of the general population. Twenty-two participants (93%) performed significantly less than the minimum daily levels of physical activity recommended by the Department of Health., Conclusions: Few adults with learning disabilities can choose to walk to work, go for a run or visit the local swimming pool without adequate support. This study suggests that there may not be enough moderate or vigorous physical activity choices available in day and residential care settings to empower adults with mild and moderate learning disabilities to meet the minimum recommendations of the Department of Health. Hence some people with learning disabilities have no alternatives to a sedentary lifestyle and the health risks associated with physical inactivity.

We identified eight cases of T-cell lymphoma with evidence of a gamma delta phenotype over a 13-year period. Seven of these cases conformed to a distinct clinicopathologic entity of hepatosplenic gamma delta T-cell lymphoma. Nearly all of these patients were young adult males (five of seven), with a median age at presentation of 20 years. They presented with marked hepatosplenomegaly, without lymphadenopathy or significant peripheral blood lymphocytosis. Thrombocytopenia was seen in all patients, and five of seven were mildly anemic. The clinical course was aggressive, and despite multiagent chemotherapy, the median survival duration was less than 1 year. The morphologic findings were uniform; a monomorphic population of medium-sized lymphoid cells with moderately clumped chromatin and a rim of pale cytoplasm infiltrated the sinusoids of the spleen, liver, and bone marrow. The cells had a characteristic immunophenotype: CD2+, CD3+, CD4-, CD5-, CD7+, CD16+, CD57-, CD25-, T-cell receptor (TCR)delta +, beta F1-. CD8 was positive in four of seven cases tested, and CD56 was positive in five of six. All cases expressed the cytotoxic granule-associated protein, TIA1, but perforin was detected in only one case. All cases with assessable DNA had a TCR gamma gene rearrangement, and lacked Epstein-Barr virus sequences. Isochromosome 7q was identified in two cases with cytogenetic information. The one case of cutaneous gamma delta T-cell lymphoma differed in its clinical manifestations, histologic appearance, and immunophenotype. We conclude that hepatosplenic gamma delta T-cell lymphoma is a distinct clinicopathologic entity derived from cytotoxic gamma delta T cells, and should be distinguished from other lymphomas of T-cell and natural-killer cell (NK)-like T-cell derivation.

This paper examines the problems of modelling bivariate relationships when repeated observations are recorded for each subject. The statistical methods required to test for a common group model were introduced using an example from exercise physiology, where the oxygen cost of running at four different speeds was recorded for a group of 30 recreationally active males. When data for each subject were studied individually, both the plots and correlations suggested the relationship to be linear. Hence, the homogeneity of the subjects' regression lines was compared using the appropriate ANOVA test. The analysis revealed a significant difference in the slopes and intercepts of the lines, thus precluding the use of a single linear model to represent the group. If the subjects were divided into two groups according to the median maximum oxygen consumption (VO2max), a multivariate analysis of variance of the slope and intercept parameters helped to explain some of this heterogeneity (P less than 0.05). However, for physiological rather than statistical reasons, it was necessary to re-analyse the data without the fourth running speed. The revised analysis suggested that the subjects' lines would be better modelled with a common slope but separate intercepts. As before, by dividing the subjects into two groups according to the median VO2max score, a simple t-test indicated that differences in the subjects' intercept parameters were not significant (P = 0.08). Notwithstanding the relatively homogeneous nature of the 30 subjects in terms of VO2max, the statistical methods showed that differences in running economy are, to some extent, dependent on VO2max.

Late-onset cerebellar degeneration can be induced transplacentally in mice by a single low-dose (1 mg/kg) injection of the direct-acting DNA alkylating agent N-methyl-N-nitrosourea (MNU) on day 16 of pregnancy. The offspring develop a mild ataxia that manifests by 12-16 weeks of age postnatally when the animals are challenged with a motor coordination task. Morphological evidence of degeneration includes pyknosis of Purkinje cells and abnormal foliation patterns. Additionally, these animals demonstrate a progressive retinopathy characterized by thinning of the nuclear and plexiform layers of the retina. Efforts to retard the cerebellar degeneration were undertaken in the present study. MNU-exposed and control animals were fed a standard mouse chow diet supplemented with 0.75% butylated hydroxytoluene (BHT), an antioxidant. This supplementation commenced 24 h following exposure to the teratogen and continued throughout the life of the offspring. A second group of MNU-exposed and control mice were fed a non-BHT-supplemented, standard Purina mouse chow diet. Quantitative histological evaluation of cerebellar coronal sections indicated that by 4 weeks of age BHT-fed, MNU-exposed mice had significantly fewer pyknotic Purkinje cells than non-BHT-fed, MNU-exposed animals. This was true for the vermal, paravermal, and lateral areas of the cerebellum. The findings suggest the usefulness of teratogenic models of degenerative diseases for the testing of potential intervention strategies.

A 1 mg/kg dose of the DNA alkylating agent, N-methyl-N-nitrosourea (MNU), when administered on day 16 of gestation provokes a progressive retinal degeneration in CD-1 albino mice reared under standard fluorescent lighting conditions (12 hr light: 12 hr dark); this degeneration begins at about 4 weeks post-natally and worsens with age. It is accelerated by constant fluorescent light exposure but is retarded greatly by constant darkness, suggesting the importance of secondary insults in the post-natal period for development of the degenerative disease. To determine whether the secondary photochemical damage might be specifically blocked, MNU-exposed and control animals in the present study were fed an antioxidant-enriched diet of Purina mouse chow supplemented with 0.75% butylated hydroxytoluene (BHT). A second group of MNU-exposed and control animals were fed a non-BHT supplemented standard Purina mouse chow diet. Systematic measurements of the number of rows of photoreceptor cell nuclei, the thickness of the inner/outer segment layer, and the thickness of the whole retina were made, to quantify and degenerative changes in animals 2, 4, 6, and 8 weeks of age. By 8 weeks, retinas of BHT-fed, MNU-exposed animals were significantly thicker and had more rows of photoreceptor cell nuclei than regular-diet, MNU-exposed animals. Moreover, the retinas of BHT-fed animals, both for MNU-exposed and controls, demonstrated sporadic morphologic changes in the form of circular configurations composed of ganglion cells, arcades of nuclear and plexiform layers, and, in one control animal, a hyperplastic nodule. These experiments suggested that MNU-induced retinal degeneration may be retarded by a BHT-enriched diet; however, continuous high doses of this compound pre- and postnatally may induce other retinal abnormalities.