Objectives: To study the training effects of eight weeks of stair climbing on VO 2 MAX, blood lipids, and homocysteine in sedentary, but otherwise healthy young women. Methods: Fifteen women (mean (SD) age 18.8 (0.7) years) were randomly assigned to control (n = 7) or stair climbing (n = 8) groups. Stair climbing was progressively increased from one ascent a day in week 1 to five ascents a day in weeks 7 and 8. Training took place five days a week on a public access staircase (199 steps), at a stepping rate of 90 steps a minute. Each ascent took about two minutes to complete. Subjects agreed not to change their diet or lifestyle over the experimental period. Results: Relative to controls, the stair climbing group displayed a 17.1% increase in VO 2 MAX and a 7.7% reduction in low density lipoprotein cholesterol (p,0.05) over the training period. No change occurred in total cholesterol, high density lipoprotein cholesterol, triglycerides, or homocysteine. Conclusions: The study confirms that accumulating short bouts of stair climbing activity throughout the day can favourably alter important cardiovascular risk factors in previously sedentary young women. Such exercise may be easily incorporated into the working day and therefore should be promoted by public health guidelines.
Background: Researchers and practitioners working in sports medicine and science require valid tests to determine the effectiveness of interventions and enhance understanding of mechanisms underpinning adaptation. Such decision making is influenced by the supportive evidence describing the validity of tests within current research. The objective of this study is to review the validity of lower body isometric multi-joint tests ability to assess muscular strength and determine the current level of supporting evidence. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed in a systematic fashion to search, assess and synthesize existing literature on this topic. Electronic databases such as Web of Science, CINAHL and PubMed were searched up to 18 March 2015. Potential inclusions were screened against eligibility criteria relating to types of test, measurement instrument, properties of validity assessed and population group and were required to be published in English. The Consensus-based Standards for the Selection of health Measurement Instruments (COSMIN) checklist was used to assess methodological quality and measurement property rating of included studies. Studies rated as fair or better in methodological quality were included in the best evidence synthesis.
A countermovement jump (CMJ) represents one of the most frequently used performance tests for monitoring neuromuscular function in athletes. An often-overlooked feature that may provide some useful diagnostic information is the actual shape of the force-time curve. The aim of this study was therefore to consider how the shape of the force-time curve influences jump performance. Thirty-three male rugby union players performed two CMJs on a force plate, with discrete variables and continuous curve analysis used. The subjects were dichotomized based on shape of the force-time curve during the propulsion phase and by jump height. The differences between the unimodal and bimodal groups were unclear for jump height (ES = 0.28, ±0.58) and reactive strength index-modified (ES = −0.30, ±0.59). A substantial difference between high (40.2 ± 2.9 cm) and low (31.2 ± 3.2 cm) jumpers only existed in the late propulsion phase by 79.0% to 97.0% of the normalized force-time curve. A bimodal force-time curve is not representative of an optimal pattern of performance and simply reflects an inefficient stretch-shortening cycle. The inter-individual variability that exists in braking COM displacement renders temporal phase analysis impractical in cross-sectional type studies.
Isometric tests have been used to assess rate of force development (RFD), however variation 29 in testing methodologies are known to effect performance outcomes. The aim of this study was 30 to assess the RFD in the isometric squat (ISqT) using two test protocols and two testing angles. 31Eleven participants (age: 26.8 4.5 years, strength training experience: 7.1 3.03 years) 32 completed test and retest sessions one week apart, whereby two test protocols with respect to 33 duration and instructions were compared. Isometric peak force (ISqT peak ) and isometric 34 explosive force (ISqT exp ) tests were assessed at two joint angles (knee flexion angle 100° and 35 125°). Force-time traces were sampled and subsequently analysed for RFD measures. Average 36 and instantaneous RFD variables did not meet reliability minimum criteria in ISqT peak at 100 37 or 125. The ISqT exp test at 100 met reliability criteria in the RFD 0-200 and 0-250ms 38 variables. The ISqT exp test at 125 met reliability criteria in the RFD 0-150, 0-200 and 0-250ms 39 variables. Force-time characteristics were optimized at the higher knee joint angle. This study 40 provides new insights into the reliability of RFD testing. Average and instantaneous RFD 41 measures obtained using a traditional peak force test do not meet basic reliability criteria. 42Researchers assessing multi-joint RFD should employ the explosive RFD test protocol as 43 opposed to the traditional isometric peak force.
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