Sand training: Exercise-induced muscle damage and inflammatory responses to matched-intensity exercise

This study compared markers of muscle damage and inflammation elevated by a matched-intensity interval running session on soft sand and grass surfaces. In a counterbalanced, repeated-measures and crossover design, 10 well-trained female athletes completed 2 interval-based running sessions 1 week apart on either a grass or a sand surface. Exercise heart rate (HR) was fixed at 83–88% of HR maximum. Venous blood samples were collected pre-, post- and 24?h post-exercise, and analysed for myoglobin (Mb) and C-reactive protein (CRP). Perceptual ratings of exertion (RPE) and muscle soreness (DOMS) were recorded immediately post- and 24?h post-exercise. A significant time effect showed that Mb increased from pre- to post-exercise on grass (p?=?.008) but not on sand (p?=?.611). Furthermore, there was a greater relative increase in Mb on grass compared with that on sand (p?=?.026). No differences in CRP were reported between surfaces (p?>?.05). The HR, RPE and DOMS scores were not significantly different between conditions (p > .05). These results suggest that in response to a matched-intensity exercise bout, markers of post-exercise muscle damage may be reduced by running on softer ground surfaces. Such training strategy may be used to minimize musculoskeletal strain while still incurring an equivalent cardiovascular training stimulus.     

The validity and reliability of a sample of 10 Wattbike cycle ergometers

ABSTRACT

The purpose of the study was to assess the validity and inter-bike reliability of 10 Wattbike cycle ergometers, and to assess the test–retest reliability of one Wattbike. Power outputs from 100 to 1000 W were applied using a motorised calibration rig (LODE) at cadences of 70, 90, 110 and 130 rev · min^?1, which created nineteen different intensities for comparison. Significant relationships (P < 0.01, r² = 0.99) were found between each of the Wattbikes and the LODE. Each Wattbike was found to be valid and reliable and had good inter-bike agreement. Within-bike mean differences ranged from 0.0 W to 8.1 W at 300 W and 3.3 W to 19.3 W at 600 W. When taking into account the manufacturers stated measurement error for the LODE (2%), the mean differences were less than 2%. Comparisons between Wattbikes at each of the nineteen intensities gave differences from 0.6 to 25.5 W at intensities of 152 W and 983 W, respectively. There was no significant difference (P > 0.05) between the measures of power recorded in the test–retest condition. The data suggest that the Wattbike is an accurate and reliable tool for training and performance assessments, with data between Wattbikes being able to be used interchangeably.     

Computerized Agility Training Improves Change-of-Direction and Balance Performance Independently of Footwear in Young Adults

Understanding the effects of training in different footwear on sporting performance would be useful to coaches and athletes. Purpose: This study compared the effects of computerized agility training using 3 types of footwear on change-of-direction and balance performance in young adults. Method: Thirty recreationally active young adults (M_age = 22.8 ± 3.1 years; M_height = 1.71 ± 0.7 m; M_bodymass = 73.4 ± 10.3 kg) were randomly assigned to a 6-week computerized agility training intervention in 1 of 3 footwear groups (n = 10/group): barefoot, minimal footwear, or traditional shoes. Participants had no previous barefoot or minimal-footwear training experience. Dependent variables included change-of-direction test time to completion, Star Excursion Balance Test, and single-leg stability evaluation. Testing was performed at the start of the training program, after 2 weeks, after 4 weeks, and at the end of the training program. Results: No group or time interactions were found for any of the dependent variables. Time main effects were observed for the performance measures of change of direction, Star Excursion, and single-leg-with-eyes-open stability evaluation. Participants improved in all 3 tests as early as 2 weeks into the intervention, with improvements continuing through the entire 6-week intervention. Conclusions: The lack of interaction and footwear effects suggests that agility and balance improvements during foot agility training are independent of footwear in a recreationally active young-adult population. Computerized agility training improves change-of-direction and balance performance within 2 weeks of training implementation. Future studies should consider footwear training effects in different populations, including frail older adults and athletes.     

Boundary-Work in the Health Research Field: Biomedical and Clinician Scientists’ Perceptions of Social Science Research

Funding agencies in Canada are attempting to break down the organizational boundaries between disciplines to promote interdisciplinary research and foster the integration of the social sciences into the health research field. This paper explores the extent to which biomedical and clinician scientists’ perceptions of social science research operate as a cultural boundary to the inclusion of social scientists into this field. Results indicated that cultural boundaries may impede social scientists’ entry into the health research field through three modalities: (1) biomedical and clinician scientists’ unfavourable and ambivalent posture towards social science research; (2) their opposition to a resource increase for the social sciences; and (3) clinician scientists procedural assessment criteria for social science. The paper also discusses the merits and limitations of Tom Gieryn’s concept of boundary-work for studying social dynamics within the field of science.

“This is the Whiteman’s Law”: Aboriginal resistance,bureaucratic change and the Census of Canada, 1830–2006

Census information of some form has been collected in Canada since the 1611 census of New France. Aboriginal people, identified or not, have been included in these enumerations. The collection of this information has had a profound impact on Aboriginal people and has been an element that has shaped their relationship with the dominant society. In response, Canadian Aboriginal people have often resisted and refused to co-operate with census takers and their masters. This article is an examination of this phenomenon focused on the censuses conducted in the post-Confederation period to the present. A census is made to collect information on populations and individuals that can then be used to configure and shape social and political relations between those being enumerated and the creators of the census. However, the human objects of the census are not just passive integers and they have resisted its creation in a number of ways, including being “missing” when the census is taken, refusing to answer the questions posed by enumerators or even driving them off Aboriginal territory. A census identifies elements of the social order and attempts to set them in their “proper” place and those who do not wish to be part of that order may refuse to take part. Archivists and historians must understand that the knowledge gained in a census is bound with the conditions of own creation. This has been noted by contemporary Aboriginal researchers who often state that the archival record of their people often distorts history and reflects the ideas and superficial observations of their Euro-Canadian creators. Changes to the Census of Canada since 1981, have increased the participation rate and therefore changed the nature of the record.

Teacher behavior, student interest and affective learning: putting theory to practice

Students of Project Adapt (PA), an instructional program for at-risk middle school students in Brooklyn NY, have displayed startling improvement on cognitive outcome measures. Teacher given grades and standardized tests illuminate the progress students have made since entering the program. The current investigation attempts to analyze PA on students' affective responses in a pre/post-test experimental design. Upon entering PA, students completed measures of interest, affect, and their previous teachers' behavior (pre). These ratings were then compared to end of year ratings on the same instruments (post). Results indicate students' perceive PA teachers utilizing different behaviors than their previous teachers. Additionally, student affect and interest increased significantly. Results of this study have implications for both instructional researchers and educational practitioners.     

Can changes in resistance exercise workload influence internal load,countermovement jump performance and the endocrine response?

This study examined the influence of differing volume load and intensity (%1 repetition maximum[%1RM]) resistance exercise workouts on session rating of perceived exertion (sRPE) countermovement jump (CMJ) performance and endocrine responses. Twelve participants performed a workout comprising four exercises (bench press, back squat, deadlift and prone bench pull) in randomised order as either power (POW); 3 sets × 6 repetitions at 45%1RM × 3 min inter-set rest, strength (ST); 3 sets × 3 repetitions at 90%1RM × 3 min inter-set rest, or hypertrophy (HYP); 3 sets × 10 repetitions at 70%1RM × 1 min inter-set rest in a randomised-crossover design. CMJ performance and endocrine responses were measured immediately pre-, post-, 12, 24, 48 and 72 h post-exercise. POW sRPE (3.0 ± 1.0) was lower than ST (4.5 ± 1.0) (P = 0.01), and both were lower than HYP (8.5 ± 1.0) (P = 0.01). Duration of CMJ decrement was longer (P ≤ 0.05) for HYP (72 h) compared to POW (12 h) and ST (24 h). Testosterone concentration was greater (P ≤ 0.05) immediately post-exercise in HYP compared to POW and ST. In conclusion, less inter-set rest, greater volume load and intensity (%1RM) may increase sRPE, duration of CMJ performance decrement and testosterone responses in resistance exercise.     

Workload and non-contact injury incidence in elite football players competing in European leagues

Purpose: The aim of this study was to analyse the relationship between absolute and acute:chronic workload ratios and non-contact injury incidence in professional football players and to assess their predictive ability. Methods: Elite football players (n?=?130) from five teams competing in European domestic and confederation level competitions were followed during one full competitive season. Non-contact injuries were recorded and using session rate of perceived exertion (s-RPE) internal absolute workload and acute:chronic (A:C) workload ratios (4-weeks, 3-weeks, 2-weeks and week-to-week) were calculated using a rolling days method. Results: The relative risk (RR) of non-contact injury was increased (RR?=?1.59, CI95%: 1.18–2.15) when a cumulative 4-week absolute workload was greater than 10629 arbitrary units (AU) in comparison with a workload between 3745 and 10628?AU. When the 3-week absolute workload was more than 8319?AU versus between 2822 and 8318?AU injury risk was also increased (RR=?1.46, CI95% 1.08–1.98). Injury incidence was higher when the 4-week A:C ratio was <0.85 versus >0.85 (RR?=?1.31, CI95%: 1.02–1.70) and with a 3-week A:C ratio >1.30 versus <1.30 (RR?=?1.37, CI95%: 1.05–1.77). Importantly, none of the A:C workload combinations showed high sensitivity or specificity. Conclusions: In elite European footballers, using internal workload (sRPE) revealed that cumulative workloads over 3 and 4 weeks were associated with injury incidence. Additionally, A:C workloads, using combinations of 2, 3 and 4 weeks as the C workloads were also associated with increased injury risk. No A:C workload combination was appropriate to predict injury.