Trained humans can exercise safely in extreme dry heat when drinking water ad libitum     

Nolte HW  Noakes TD  Van Vuuren B 《Journal of sports sciences》2011,29(12):1233-1241

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Participation-related relative age effects in Masters swimming: a 6-year retrospective longitudinal analysis     

Medic N  Young BW  Medic D 《Journal of sports sciences》2011,29(1):29-36

Medic and colleagues (Medic, Starkes, & Young, 2007) found that relatively younger cohorts of Masters athletes had higher participation rates and achieved higher performances compared with a relatively older cohort. Considering that Medic and colleagues' (2007) study was cross-sectional in nature, the purpose of this investigation was to employ a retrospective longitudinal study design to examine the participation rates of Masters swimmers as a function of an individual's constituent year within any 5-year age category over a period of 6 years. Using archived data from the 2003 to 2009 US Masters Short Course National Championships, swimmers' attendance was followed for a period of six consecutive years. Results indicated that a participation-related relative age effect was observed among swimmers who, over a period of 6 years, competed in either at least one championship (N = 2596; Cochran's Q? = 64.16, r(s) = -0.92, both P < 0.0001) or at least three championships (N = 441; Cochran's Q? = 47.51, r(s) = -0.91, both P < 0.0001). Overall, effect size analyses indicated that the odds of a Masters swimmer participating in the championship during the first constituent year of any 5-year age category was more than two times greater than the odds of that athlete participating during the fifth constituent year.  相似文献   

The secular trend for grip strength in Canada and the United States     

Silverman IW 《Journal of sports sciences》2011,29(6):599-606

Worldwide, body weight has risen dramatically in recent decades, raising the question of whether there were concomitant changes in physical fitness. Past research with children and adolescents has shown that body weight and grip strength are positively correlated. Therefore, it was predicted that grip strength had increased on average in children and adolescents over the past four or five decades. To test this prediction, relevant data were extracted from 18 studies for males (N = 5676 in total) and 17 studies for females (N = 5489 in total). The studies were conducted in Canada and the United States from about 1966 on, with participants' ages ranging from 6 through 19 years. Weighted least squares regression analyses showed that grip strength was significantly predicted by age but not by country. Male grip strength decreased significantly over the period covered, but the change was very small, accounting for far less than 1% of the variance in male grip strength. Discussion focuses on potential explanations for why grip strength did not change over time as predicted.  相似文献   

Let’s talk about sex and sports     

Dr. Daniela Schaaf  Dr. Jörg-Uwe Nieland 《Sportwissenschaft》2011,41(1):62-64

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Effect of different swim caps on the assessment of body volume and percentage body fat by air displacement plethysmography     

Peeters MW  Claessens AL 《Journal of sports sciences》2011,29(2):191-196

Isothermal air trapped in scalp hair generates an underestimation of body volume when it is measured by air displacement plethysmography. The aim of this study was to examine the effect of wearing different types of swim caps on the measurement of body volume and percentage body fat by air displacement plethysmography. It was hypothesized that wearing a silicone swim cap would more thoroughly compress scalp hair compared with a lycra swim cap, yielding higher estimates of body volume and percent body fat. Thirty female participants aged 25.7 ± 6.4 years were measured in random order when wearing no swim cap, a lycra swim cap or a silicone swim cap. For the no-cap versus lycra cap condition, the mean bias for body volume was -0.579 ± 0.380 litre (limits of agreement: -1.340 to 0.181 litre) and for percent fat -4.9 ± 3.1% fat (limits of agreement: -11.2 to 1.3% fat) (P < 0.05). For the silicone versus lycra condition, the mean bias for body volume was 0.137 ± 0.099 litre (limits of agreement: -0.062 to 0.335 litre) and for percent fat 1.2 ± 0.9% fat (limits of agreement: -0.5 to 2.9% fat) (P < 0.05). In conclusion, attention should be paid to optimal compression of isothermal air trapped in scalp hair when using air displacement plethysmography. The present results suggest that this compression may be more thorough when wearing a silicone swim cap.  相似文献   

Effects of cold water immersion on the recovery of physical performance and muscle damage following a one-off soccer match     

Ascensão A  Leite M  Rebelo AN  Magalhäes S  Magalhäes J 《Journal of sports sciences》2011,29(3):217-225

The aim of this study was to assess the effects of a single session of cold or thermoneutral water immersion after a one-off match on muscular dysfunction and damage in soccer players. Twenty-male soccer players completed one match and were randomly divided into cryotherapy (10 min cold water immersion, 10°C, n = 10) and thermoneutral (10 min thermoneutral water immersion, 35°C, n = 10) groups. Muscle damage (creatine kinase, myoglobin), inflammation (C-reactive protein), neuromuscular function (jump and sprint abilities and maximal isometric quadriceps strength), and delayed-onset muscle soreness were evaluated before, within 30 min of the end, and 24 and 48 h after the match. After the match, the players in both groups showed increased plasma creatine kinase activity (30 min, 24 h, 48 h), myoglobin (30 min) and C-reactive protein (30 min, 24 h) concentrations. Peak jump ability and maximal strength were decreased and delayed-onset muscle soreness increased in both groups. However, differential alterations were observed between thermoneutral water and cold water immersion groups in creatine kinase (30 min, 24 h, 48 h), myoglobin (30 min), C-reactive protein (30 min, 24 h, 48 h), quadriceps strength (24 h), and quadriceps (24 h), calf (24 h) and adductor (30 min) delayed-onset muscle soreness. The results suggest that cold water immersion immediately after a one-off soccer match reduces muscle damage and discomfort, possibly contributing to a faster recovery of neuromuscular function.  相似文献   

The effect of patellar taping on EMG activity of vasti muscles during squatting in individuals with patellofemoral pain syndrome     

Mostamand J  Bader DL  Hudson Z 《Journal of sports sciences》2011,29(2):197-205

Although patellar taping has been shown to reduce pain in participants with patellofemoral pain syndrome, the mechanisms of pain reduction have not completely been established following its application. The purpose of this study was to evaluate EMG activity of vastus medialis and vastus lateralis following the application of patellar taping during a functional single leg squat. Both vastus medialis obliquus-vastus lateralis onset and vastus medialis obliquus/vastus lateralis amplitude of 18 participants with patellofemoral pain syndrome and 18 healthy participants as controls were measured using an EMG unit. This procedure was performed on the affected knee of participants with patellofemoral pain syndrome, before, during, and after patellar taping during unilateral squatting. The same procedure was also performed on the unaffected knees of both groups. The mean values of vastus medialis obliquus-vastus lateralis onset prior to taping (2.54 ms, s = 4.35) were decreased significantly following an immediate application of tape (-3.22 ms, s = 3.45) and after a prolonged period of taping (-6.00 ms, s = 3.40 s) (P < 0.05). There was also a significant difference between the mean values of vastus medialis obliquus-vastus lateralis onset among controls (-2.03 ms, s = 6.04) and participants with patellofemoral pain syndrome prior to taping (P < 0.05). However, there were no significant difference between the ranked values of vastus medialis obliquus/vastus lateralis amplitude of the affected and unaffected knees of participants with patellofemoral pain syndrome and controls during different conditions of taping (P > 0.05). Decreased values of vastus medialis obliquus-vastus lateralis onset may contribute to patellar realignment and explain the mechanism of pain reduction following patellar taping in participants with patellofemoral pain syndrome.  相似文献   

Automaticity of exercise self-regulatory efficacy beliefs in adults with high and low experience in exercise self-regulation     

Buckley J  Cameron LD 《运动与训练心理学杂志》2011,33(3):325-348

Guided by social cognitive theory (SCT), we investigated whether exercise self-regulatory efficacy beliefs can be activated nonconsciously in individuals experienced and inexperienced in exercise self-regulation, and whether these beliefs are automatically associated with exercise self-regulation processes. The study used a 2 (Exercise Self-Regulation Experience Group) × 3 (Prime Condition) between-subjects design in which individuals experienced and inexperienced in exercise self-regulation were randomly assigned to receive subliminal, supraliminal, or no priming of exercise self-regulatory efficacy beliefs. Participants completed hypothetical diary entries, which were assessed for exercise self-regulatory efficacy and self-regulation expressions using content analyses with a SCT coding system and the Linguistic Inquiry and Word Count (LIWC) text analysis program. For both exercise self-regulation experience groups, self-efficacy priming led to more expressions of low exercise self-regulatory efficacy and dysfunctional exercise self-regulation strategies compared with the control prime. For participants experienced in exercise self-regulation, supraliminal priming (vs. control priming) led to more expressions of high exercise self-regulatory efficacy and functional exercise self-regulation strategies. For the experienced groups, priming led to automaticity of exercise expressions compared with the control condition. For inexperienced participants in the subliminal prime condition, priming led to automaticity of self-regulatory efficacy beliefs and work-related goals compared with the control condition. Automatic activation of exercise self-regulatory efficacy and exercise self-regulation processes suggests that self-regulation of exercise behavior can occur nonconsciously.  相似文献   

The real woman behind Ammonite: Tom Sharpe,The Fossil Woman: A Life of Mary Anning,Dovecote Press, 2020, 240pp, £20, plus 32 colour plates,ISBN 978-0-9955462-9-5     

Thomas W. Goodhue 《Endeavour》2021,45(1-2):100747

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Facilitators and inhibitors for integrating expertise diversity in innovation teams: The case of plasmid exchange in molecular biology     

Michael A. Zaggl  Judith Pottbäcker 《Research Policy》2021,50(9):104313

Innovation increasingly relies on collaboration in teams instead of individual efforts. Although the advantages of teams for innovating are virtually undisputed, we have only a very rudimentary understanding of their success drivers. To shed more light on innovation teams, we conceptualize multiplicity in expertise as nonredundant expertise and distinguish it from factors that facilitate or hinder the integration of this expertise. These factors are overlap in expertise, disparity in team members’ status, and whether or not teams use automation technology. We use the empirical context of molecular biology, especially the part of this field in which teams produce and exchange genetic material in the form of so-called plasmids. Combining data about plasmids from a central plasmid repository (AddGene) with bibliometric data endows us with a rich dataset capturing information about team diversity in addition to two innovation performance measures (the number of plasmid orders and the number of citations attracted by publications). Our analysis shows that multiplicity in expertise increases innovation performance; this relationship is strengthened by the overlap in expertise and weakened by disparity in status and the use of the automation technology. Our paper provides a more detailed theory of expertise diversity and contributes to the diversity literature. Our findings also lead to implications for practitioners.  相似文献