Effects of strength and endurance exercise order on endocrine responses to concurrent training     

Thomas W. Jones  Glyn Howatson  Mark Russell 《European Journal of Sport Science》2017,17(3):326-334

The present study examined the effect of strength and endurance training order on the endocrine milieu associated with strength development and performance during concurrent training. A randomised, between-groups design was employed with 30 recreationally resistance-trained males completing one of four acute experimental training protocols; strength training (ST), strength followed by endurance training (ST-END), endurance followed by strength training (END-ST) or no training (CON). Blood samples were taken before each respective exercise protocol, immediately upon cessation of exercise, and 1?h post cessation of exercise. Blood samples were subsequently analysed for total testosterone, cortisol and lactate concentrations. Ability to maintain 80% 1RM during strength training was better in ST and ST-END than END-ST (both p?<?.05). Immediately following the respective exercise protocols all training interventions elicited significant increases in testosterone (p?<?.05). ST and END-ST resulted in greater increases in cortisol than ST-END (both p?<?.05). The testosterone:cortisol ratio was similar following the respective exercise protocols. Blood lactate concentrations post-training were greater following END-ST and ST than ST-END (both p?<?.05). Conducting endurance exercise prior to strength training resulted in impaired strength training performance. Blood cortisol and lactate concentrations were greater when endurance training was conducted prior to strength training than vice versa. As such, it may be suggested that conducting endurance prior to strength training may result in acute unfavourable responses to strength training when strength training is conducted with high loads.  相似文献   

Kinematical analysis of the V2 ski skating technique: A longitudinal study     

Thomas Losnegard  Håvard Myklebust  Angela Ehrhardt  Jostein Hallén 《Journal of sports sciences》2017,35(12):1219-1227

To characterise timing of movements and evaluate performance effects of technique alterations in V2 ski skating, 13 elite male cross-country skiers (age, 23 ± 2 years; stature, 182 ± 6 cm; body mass, 76 ± 8 kg; V2 V?O_2max, 79.3 ± 4.4 mL · kg^?1 · min^?1) were tested four times during the preparation and competition phase on a roller ski treadmill. Each test consisted of submaximal intensities of exercise for determination of oxygen cost followed by one 1000-m performance test. Hip movement (from accelerometer data) and joint angles (2D video) were determined for high-intensity exercise (6° and 3.5 m · s^?1; ~ 97–100% of V?O_2peak). Each ski thrust consisted of three phases: gliding phase (18–50% of cycle time), poling phase (50–70% of cycle time), and kick phase (70–78% of cycle time). Flexion/extension of the hip initiated all phases, followed by the respective joints in legs and arms. Mixed-model analysis, adjusting for systematic time-point effects, identified that both reduced vertical hip acceleration and increased cycle time gave a small likely reduction in oxygen cost and 1000-m time. In conclusion, well-developed hip movement is a key characteristic of the V2 technique for elite-standard skiers’ long-term performance development.  相似文献   

Associations between prolonged sedentary time and breaks in sedentary time with cardiometabolic risk in 10–14-year-old children: The HAPPY study     

Daniel P. Bailey  Sarah J. Charman  Thomas Ploetz  Louise A. Savory  Catherine J. Kerr 《Journal of sports sciences》2017,35(22):2164-2171

This study examines the association between prolonged sedentary time and breaks in sedentary time with cardiometabolic risk in 10–14-year-old children. This cross-sectional design study analysed accelerometry-determined sedentary behaviour and physical activity collected over 7 days from 111 (66 girls) UK schoolchildren. Objective outcome measures included waist circumference, fasting lipids, fasting glucose, blood pressure, and cardiorespiratory fitness. Logistic regression was used for the main data analysis. After adjustment for confounders, the odds of having hypertriglyceridaemia (P = 0.03) and an increased clustered cardiometabolic risk score (P = 0.05) were significantly higher in children who engaged in more prolonged sedentary bouts per day. The number of breaks in sedentary time per day was not associated with any cardiometabolic risk factor, but longer mean duration of daily breaks in sedentary time were associated with a lower odds of having abdominal adiposity (P = 0.04) and elevated diastolic blood pressure (P = 0.01). These associations may be mediated by engagement in light activity. This study provides evidence that avoiding periods of prolonged uninterrupted sedentary time may be important for reducing cardiometabolic disease risk in children.  相似文献   

Extracurricular Physical Activity Programs in California Private Secondary Schools     

David Kahan  Thomas L. McKenzie 《Research quarterly for exercise and sport》2017,88(4):524-529

Purpose: Interscholastic, intramural, and club physical activity (PA) programs can be important contributors to student PA accrual at schools. Few studies have assessed factors related to the provision of these extracurricular PA programs, especially in private schools. Methods: We used a 16-item questionnaire to assess the associations and influences of selected factors relative to extracurricular PA program policies and practices in 450 private California secondary schools. Associations were evaluated using contingency table analyses (i.e., chi-squared, effect size, and post-hoc analyses). Results: Six factors were associated with schools providing extracurricular PA programs: school location, level, enrollment, and religious classification and whether the physical education (PE) program met state PE time standards and was taught by PE specialists. Conclusions: Both static factors (e.g., school location, level, enrollment, and religious affiliation) and modifiable factors (e.g., meeting PE standards and employing specialists) affect the provision of extracurricular PA programs. As education is state-mandated, additional study is recommended to assess the generalizability of these findings to other states and to public schools.  相似文献   

The effect of mountain bike wheel size on cross-country performance     

Howard Thomas Hurst  Jonathan Sinclair  Stephen Atkins  Lee Rylands  John Metcalfe 《Journal of sports sciences》2017,35(14):1349-1354

ABSTRACT

The purpose of this study was to determine the influence of different wheel size diameters on indicators of cross-country mountain bike time trial performance. Nine competitive male mountain bikers (age 34.7 ± 10.7 years; stature 177.7 ± 5.6 cm; body mass 73.2 ± 8.6 kg) performed 1 lap of a 3.48 km mountain bike (MTB) course as fast as possible on 26″, 27.5″ and 29″ wheeled MTB. Time (s), mean power (W), cadence (revs · min^?1) and velocity (km · h^?1) were recorded for the whole lap and during ascent and descent sections. One-way repeated measure ANOVA was used to determine significant differences. Results revealed no significant main effects for any variables by wheel size during all trials, with the exception of cadence during the descent (F_{(2, 16)} = 8.96; P = .002; P² = .53). Post hoc comparisons revealed differences lay between the 26″ and 29″ wheels (P = .02). The findings indicate that wheel size does not significantly influence performance during cross-country when ridden by trained mountain bikers, and that wheel choice is likely due to personal choice or sponsorship commitments.  相似文献   

Studies of Physical Education in the United States Using SOFIT: A Review     

Thomas L. McKenzie  Nicole J. Smith 《Research quarterly for exercise and sport》2017,88(4):492-502

Purpose: An objective database for physical education (PE) is important for policy and practice decisions, and the System for Observing Fitness Instruction Time (SOFIT) has been identified as an appropriate surveillance tool for PE across the nation. The purpose of this review was to assess peer-reviewed studies using SOFIT to study K–12 PE in U.S. schools. Method: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses informed the review, and 10 databases were searched for English-language articles published through 2016. A total of 704 records identifying SOFIT were located, and 137 full texts were read. Two authors reviewed full-text articles, and a data extraction tool was developed to select studies and main topics for synthesis. Results: Twenty-nine studies that included direct observations of 12,256 PE lessons met inclusion criteria; 17 were conducted in elementary schools, 9 in secondary schools, and 3 in combined-level schools. Inconsistent reporting among studies was evident, including not all identifying the number of classes and teachers involved. All studies reported student physical activity, but fewer reported observer reliabilities (88%), lesson context (76%), teacher behavior (38%), and PE dosage (34%). The most frequently analyzed independent variables were teacher preparation (48%), lesson location (38%), and student gender (31%). Conclusions: SOFIT can be used reliably in diverse settings. Inconsistent reporting about study procedures and variables analyzed, however, limited comparisons among studies. Adherence to an established protocol and more consistent reporting would more fully enable the development of a viable database for PE in U.S. schools.  相似文献   

Making Science Relevant: The Experiences of Prospective Elementary School Teachers in an Innovative Science Content Course     

McLoughlin  Andrea Sabatini  Dana  Thomas M. 《Journal of Science Teacher Education》1999,10(2):69-91

Journal of Science Teacher Education -  相似文献   

Relationship Between Counselor and Client Perceptions of Psychological Problems and Counseling Outcomes     

Ramona N. Mellott  Thomas J. DeStefano  Julie French-Bloomfield  Voyko Kavcic 《Journal of College Counseling》1999,2(2):134-147

This study examined congruence levels between client and counselor beliefs about psychological problems and its impact on counseling outcomes. Clients and counselors endorsed differing views for causation and treatment of psychological problems. Counseling outcomes were unaffected by congruence levels. Practical implications for college counseling staff are provided.  相似文献   

The Organizational Outsider Within     

Karen L. Proudford  Kecia M. Thomas 《Journal of Career Development》1999,26(1):3-5

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The Effects of Videoconferencing,Class Size,and Learner Characteristics on Training Outcomes     

Kenneth G. Brown  Thomas A. Rietz  Brenda Sugrue 《Performance Improvement Quarterly》2005,18(1):59-82

ABSTRACT We examined direct and interaction effects of learners' characteristics (cognitive ability, prior knowledge, prior experience, and motivation to learn) and classroom characteristics (videoconferencing and class size) on learning from a 16-week course. A 2times2 quasi-experimental design varied the class size between large (∼60 students) and small (∼30 students) and between traditional classes with the instructor always present and classes taught using a videoconferencing system with the instructor present at each site every other week. Theory regarding instructor immediacy was used to predict that larger and videoconferenced classes would have negative effects on learner reactions and learning, but that highly motivated learners would overcome the negative effects on learning. Interactions between videoconferencing and motivation to learn, and class size and motivation to learn, were found in support of the theory. Research and practice implications are discussed.  相似文献