Application of velocity loss thresholds during free-weight resistance training: Responses and reproducibility of perceptual,metabolic, and neuromuscular outcomes

ABSTRACT

The aim of this study was to investigate the differences and long-term reliability in perceptual, metabolic, and neuromuscular responses to velocity loss resistance training protocols. Using a repeated, counterbalanced, crossover design, twelve team-sport athletes completed 5-sets of barbell back-squats at a load corresponding to a mean concentric velocity of ~0.70 m·s^?1. On different days, repetitions were performed until a 10%, 20% or 30% velocity loss was attained, with outcome measures collected after each set. Sessions were repeated after four-weeks. There were substantial between-protocol differences in post-set differential ratings of perceived exertion (dRPE, i.e., breathlessness and leg muscles, AU) and blood lactate concentration (B[La], mmol·L^?1), such that 30%>20%>10% by small to large magnitudes. Differences in post-set countermovement jump (CMJ) variables were small for most variables, such that 30%<20%<10%. Standard deviations representing four-week variability of post-set responses to each protocol were: dRPE, 8–11; B[La], 0.8–1.0; CMJ height, 1.6–2.0; CMJ PPO, 1.0–1.8; CMJ PCV, 0.04–0.06; CMJ 100ms-Impulse, 5.7–11.9. Velocity loss thresholds control the magnitude of perceptual, metabolic, and neuromuscular responses to resistance training. For practitioners wanting to reliably prescribe training that can induce a given perceptual, metabolic, or neuromuscular response, it is strongly advised that velocity-based thresholds are implemented.     

The diffusion of ideas in the academy: A quantitative illustration from economics

It has long been recognised in policy discussion that the influence of new ideas depends not just on their generation but also on the way in which they diffuse through society. However, while the spread of new ideas in industry has been much studied, there are no similar quantitative studies on diffusion within the academy. This paper addresses that gap by providing quantitative evidence on the adoption of two techniques for empirically testing hypotheses in economics. On the basis of this evidence, and contrary to a common expectation, the spread of ideas seems neither straightforward nor especially rapid in the academy.     

Delay in disclosure of childhood rape: results from a national survey

OBJECTIVE: This study sought to gather representative data regarding the length of time women who were raped before age 18 delayed prior to disclosing such rapes, whom they disclosed to, and variables that predicted disclosure within 1 month. METHOD: Data were gathered from 3,220 Wave II respondents from the National Women's Study (Resnick, Kilpatrick, Dansky, Saunders, & Best, 1993), a nationally representative telephone survey of women's experiences with trauma and mental health. Of these, 288 retrospectively reported at least one rape prior to their 18th birthday. Details of rape experiences were analyzed to identify predictors of disclosure within 1 month. RESULTS: Fully 28% of child rape victims reported that they had never told anyone about their child rape prior to the research interview; 47% did not disclose for over 5 years post-rape. Close friends were the most common confidants. Younger age at the time of rape, family relationship with the perpetrator, and experiencing a series of rapes were associated with disclosure latencies longer than 1 month; shorter delays were associated with stranger rapes. Logistic regression revealed that age at rape and knowing the perpetrator were independently predictive of delayed disclosure. CONCLUSIONS: Delayed disclosure of childhood rape was very common, and long delays were typical. Few variables were identified that successfully predicted disclosure behavior, but older age and rape by a stranger were associated with more rapid disclosure. This suggests that the likelihood of disclosure in a given case is difficult to estimate, and predictions based on single variables are unwarranted.     

Foraging on the radial-arm maze: Effects of altering the reward at a target location

Thirsty rats were trained to collect small water rewards from the end of each arm of an eight-arm radial maze. During these training trials and subsequent testing trials, the subjects were allowed to choose a maximum of eight arms. “Preference” for a target maze location was studied by noting when, in the sequence of eight choices, the target was selected. During testing, when one maze location was consistently devoid of water, rats decreased their preference for this arm over trials (Experiment 1). Similarly, rats that learned a saccharin-lithium association demonstrated lower preferences for a maze location that consistently held the conditioned saccharin solution. This was true for animals that received saccharin-lithium conditioning on the maze (Experiment 3A) and for animals conditioned to saccharin in a separate context (Experiment 3B). An increase in preference for a target maze location consistently containing a sweet chocolate milk solution was observed in animals that were water- and food-deprived (Experiment 2). These studies demonstrate that animals will modify their responses toward (preferences for) maze locations that predictably contain an altered reward.     

One bottle too many? Method of testing determines the detection of overshadowing and retention of taste aversions

A two-bottle testing method generally is regarded as a more sensitive measure of taste aversions than a one-bottle test. The current research compared the sensitivity of one-bottle and two-bottle tests in the detection of taste aversions. Specifically, the experiments were designed to detect both overshadowing (single- vs. compound-element conditioning) and retention interval (5 days vs. 1 day) effects. The groups tested with the one-bottle method evidenced both significant overshadowing and stronger aversions at 5-day retention intervals. On the other hand, the differences on these measures were not significant with the two-bottle tests. It is suggested that the efficacy of the two-bottle test be re-evaluated since it may obscure between-group differences in aversion strength.     

Indigenous graduate research students in Australia: a critical review of the research

Over the last decade, there has been a steady increase in the number of Indigenous graduate research students in Australia, yet research and pedagogy has not kept pace with changes underway in the sector. From an extensive search of literature published between 2000 and 2017, 15 papers (representing 10 research projects conducted by seven teams or authors) were identified that addressed Indigenous graduate research student experience. Overall, the literature tends to focus on identifying barriers to completion, noting in particular the impact of financial difficulties, social isolation and racism. A research degree is a key site for the assertion and legitimation of Indigenous knowledges, and it is here that Indigenous students are navigating tensions between legitimated disciplinary practices of the centre and the peripheral status of Indigenous knowledges. We, therefore, adopt Herbert's ‘centre–periphery’ model to interpret the research, arguing that this framework explains the focus on barriers, the neglect of pedagogy centred on academic excellence and student strengths, and research relationships between students and Indigenous communities. Our review identifies the need for a systematic research agenda specifically focused on Indigenous student success at the graduate research level, and looking internationally in order to assess the performance and strategies of Australian higher education providers in comparison to international institutions meeting the aims of First Nations research communities. This approach, we suggest, should move beyond an analysis of the nature of enablers and barriers to focus on Indigenous Higher Degree by Research success.     

Development of sex-trait stereotypes among young children in the United Staes, England, and Ireland

The Sex Stereotype Measure II (SSM II), a 32-item revision of the Williams, Bennett, and Best Sex Stereotype Measure, was developed to assess children's knowledge of conventional, sex-trait stereotypes defined by American university students. The procedure employed brief stories and human figure silhouettes which were individually administered to 5- and 8-year-old children in the United States, England, and Ireland and group administered to 11-year-olds in the United States. In the United States, knowledge of sex-trait stereotypes was found to develop in a linear fashion between the ages of 5 and 11, with more male traits than female traits being known at each age level. Cross-nationally, there was a high degree of similarity in the nature of the sex stereotypes being learned by the children in the 3 countries, although the rate of learning appeared slower among the Irish children. In all countries there was a clear progression in sex-stereotype learning from age 5 to age 8. English boys had greater knowledge of stereotypes than English girls, but this was not true in Ireland and the United States. Generally, knowledge of male stereotype traits appeared to develop earlier while knowledge of the female traits increased more rapidly between ages 5 and 8. The similarity in sex-stereotype learning in the 3 countries is discussed, and studies in progress in other countries of greater cultural diversity are noted.     

Physiological Responses to Maximal Treadmill and Handweighted Exercise

Abstract

The purpose of this investigation was to compare the peak physiological responses among four protocols that employed different amounts of handweighted exercise in 16 males (aged 26.3 ± 4.1 years). The four protocols were (a) uphill treadmill running (UR; 3.36 m-s¹, 2.5% grade increase-3 min¹); (b) uphill treadmill walking while pumping 1.36kg handweights (HW) (UWHW; 1.79ms¹, 5.0% grade increase-3 min¹; (c) treadmill walking while pumping .91-kg HW (WHW; 1.79 m-s¹, 0% grade, .91kg HW increase-3 min¹); and (d) standing in place and pumping HW (SHW; arm work as described in WHW). It was hypothesized that the peak responses would be inversely proportional to the estimated muscle mass activated (i.e., UR = UWHW > WHW > SHW). Dependent variables included peak oxygen uptake (VO₂ peak), peak heart rate (HRpeak), peak ventilation (V_epeak), and peak respiratory exchange ratio (RERpeak). No differences were noted between UR and UWHW with respect to any of the dependent variables. All variables (except RERpeak) were greater (p < .01) in UR and UWHW than either WHW or SHW. RERpeak was greater (p < .01) in UR and UWHW than in WHW. VO₂peak and HRpeak were greater (p < .01) in WHW when compared to SHW. Mean VO₂peak was 97.5, 69.7, and 60% of UR for UWHW, WHW, and SHW, respectively. Therefore, walking and pumping handweights provides a maximal stimulus to the oxygen transport system.