athletes. 19 Variations in IMTP kinetics reported across the literature may be partially explained by methodological differences. 2 , 8 , 13 , 16 , 18 Early research used a sampling frequency of 500 Hz and 600 Hz, 8 , 13 whereas more recent investigations have implemented a sampling frequency of 1000 Hz
Thomas Dos’Santos, Paul A. Jones, Jonathan Kelly, John J. McMahon, Paul Comfort and Christopher Thomas
Yani L. Dickens, Judy Van Raalte and Russell T. Hurlburt
-aloud methods presume that thinking translates easily and contemporaneously into words, typically focus on thoughts at the expense of other inner experiences such as emotions or sensations, lack random and representative sampling in favor of ongoing, continuous real-time reporting ( Hurlburt, 2011 ), and may be
Thomas Dos’Santos, Paul A. Jones, Jonathan Kelly, John J. McMahon, Paul Comfort and Christopher Thomas
Skeletal-muscle function can be evaluated using force–times curves generated via the isometric midthigh pull (IMTP). Various sampling frequencies (500–1000 Hz) have been used for IMTP assessments; however, no research has investigated the influence of sampling frequency on IMTP kinetics. Therefore, the purpose of this study was to investigate the influence of sampling frequency on kinetic variables during the IMTP, including peak force, time-specific force values (100, 150, and 200 ms), and rate of force development (RFD) at 3 time bands (0–100, 0–150, 0–200 ms).
Academy rugby league players (n = 30, age 17.5 ± 1.1 y, height 1.80 ± 0.06 m, mass 85.4 ± 10.3 kg) performed 3 IMTP trials on a force platform sampling at 2000 Hz, which was subsequently down-sampled to 1500, 1000, and 500 Hz for analysis.
Intraclass correlation coefficients (ICC) and coefficients of variation (CV) demonstrated high within-session reliability for all force and RFD variables across all sampling frequencies (ICC ≥ .80, CV ≤ 10.1%). Repeated-measures analysis of variance revealed no significant differences (P > .05, Cohen d ≤ 0.009) in kinetic variables between sampling frequencies. Overall, high reliability was observed across all sampling frequencies for all kinetic variables, with no significant differences (P > .05) for each kinetic variable across sampling frequencies.
Practitioners and scientists may consider sampling as low as 500 Hz when measuring peak force, time-specific force values, and RFD at predetermined time bands during the IMTP for accurate and reliable data.
Paul J. McCarthy and Marc V. Jones
This focus group study examined the sources of enjoyment and nonenjoyment among younger and older English children in the sampling years of sport participation (ages 7–12). Concurrent inductive and deductive content analysis revealed that, consistent with previous research, younger and older children reported sources of enjoyment such as perceived competence, social involvement and friendships, psychosocial support, and a mastery-oriented learning environment. Nonenjoyment sources included inappropriate psychosocial support, increasing competitive orientation, negative feedback and reinforcement, injuries, pain, and demonstrating a lack of competence. Differences between younger and older children’s sources of enjoyment and nonenjoyment also emerged. Younger children reported movement sensations as a source of enjoyment and punishment for skill errors and low informational support as nonenjoyment sources. Older children reported social recognition of competence, encouragement, excitement, and challenge as sources of enjoyment with rivalry, overtraining, and high standards as sources of nonenjoyment. These differences underscore the importance of tailoring youth sport in the sampling years to the needs of the child.
Lindsy Kass and Roger Carpenter
To compare blood lactate concentration ([Bla]) at 15 s and 45 s during the 1-min rest period between each stage of an incremental test in rowers and to establish the validity of using interchangeable sampling times.
Seventeen male club rowers (mean ± SD, age 28.8 ± 5.7 years, height 186.9 ± 5.1 cm, body mass 85.4 ± 6.6 kg) performed an incremental rowing ergometer test, consisting of five stages of 4 min corresponding to approximately 80% HRmax. A 10-µL earlobe blood sample was collected from each subject at 15 s and again at 45 s in the final minute of each test stage and analyzed in duplicate. A maximum of 10 s was allowed for blood collection.
Statistical analysis using limits of agreement and correlation indicated a high level of agreement between the two [Bla] samples for all fve test stages (agreement >95%, confidence intervals [CI] = -0.5 to 1.5, r = .97, P < .05).
These results suggest that a sampling time between 15 s and 45 s may be recommended for the valid assessment of the [Bla] threshold in rowing performance monitoring. This extends the current sampling time of 30 s used by physiologists and coaches for National and club-level Rowers.
Jacky J. Forsyth, Chris Mann and James Felix
In rowing ergometry, blood for determining lactate concentration can be removed from the toe tip without the rower having to stop. The purpose of the study was to examine whether sampling blood from the toe versus the earlobe would affect lactate threshold (Tlac) determination.
Ten physically active males (mean ± age 21.2 ± 2.3 y; stature 179.2 ± 7.5 cm; body mass 81.7 ± 12.7 kg) completed a multistage, 3 min incremental protocol on the Concept II rowing ergometer. Blood was sampled simultaneously from the toe tip and earlobe between stages. Three different methods were used to determine Tlac.
There were wider variations due to the method of Tlac determination than due to the sample site; for example, ANOVA results for power output were F(1.25, 11.25) = 11.385, P = .004 for method and F(1, 9) = 0.633, P = .45 for site. The greatest differences in Tlac due to sample site in rowing occurred when Tlac was determined using an increase in blood lactate concentration by >1 mmol/L from baseline (TlacΔ1).
The toe tip can be used as a suitable sample site for blood collection during rowing ergometry, but caution is needed when using the earlobe and toe tip interchangeably to prescribe training intensities based on Tlac, especially when using TlacΔ1 or at lower concentrations of lactate.
Stephen W. Garland and Greg Atkinson
To assess the effect of sample site (earlobe vs toe) and incremental exercise protocol (continuous vs discontinuous) on training zone prescription in rowing.
Twenty-six rowers performed two incremental exercise tests on an ergometer: (1) a five-step discontinuous test with 4-min stages and 30-W increment, with blood samples taken from the earlobe and toe at the start of the 1-min break between steps; (2) a continuous test, with 2-min stages and 30-W increment, with blood samples taken from the right first toe at the end of each stage. Blood was analyzed for lactate concentration.
At a lactate concentration of 2 mmol·L−1, the mean (95% CI) power output was 8.1 (± 15.4) W greater for the continuous protocol, the random error between the methods (1.96 × SD of differences) was ± 58.8 W, and there was no evidence of any relationship between power output and error between methods. At a lactate concentration of 4 mmol·L−1, the mean (95% CI) power output was 24.2 (± 17.0) W greater for the continuous protocol, and the random error was ± 64.8 W. At 4 mmol·L−1, systematic bias between methods increased with high power outputs.
The continuous protocol with toe sampling led to higher power outputs for a given lactate concentration compared with the discontinuous protocol with earlobe sampling. This was partly due to the choice of sample site and largely due to the choice of protocol. This bias, and also random variability, makes direct comparison of these tests inappropriate.
Simon Fryer, Tabitha Dickson, Stephen Hillier, Lee Stoner, Carl Scarrott and Nick Draper
Venipuncture is expensive, invasive, and impractical for many sport-science and clinical-based settings. Salivary free cortisol is often cited as a noninvasive practical alternative. However, when cortisol concentrations exceed the corticosteroid-binding globulin (CBG) point of 500 nmol/L, a lack of agreement between salivary and venous blood cortisol has been found. Alternatively, capillary blood may present a minimally invasive, cost-effective, and practical surrogate for determining cortisol concentration.
The aim of this study was to determine whether cortisol concentrations sampled from capillary blood and saliva accurately reflect those found in venous blood across a large range of concentrations after intense exercise.
Eleven healthy aerobically trained male subjects were recruited. Capillary, salivary, and venous blood samples were collected before and after (immediately and 5, 10, 15, and 20 min after) a treadmill VO2 max test.
Capillary and venous concentrations increased at a similar rate after exercise (Cohen d.14–.33), increasing up to 15 min postexercise before a decline was seen. Salivary cortisol values increased at a slower rate than venous and capillary cortisol but continued to increase 15 min postexercise (Cohen d .19–.47 and .09–.72, respectively).
Capillary cortisol accurately reflects concentrations assayed from venous blood across a range of values below and above the CBG binding point. Capillary sampling provides a minimally invasive, cost-effective, practical surrogate for assessment of hypothalamic-pituitary-gland function.
Deborah Leachman Slawson, Barbara S. McClanahan, Linda H. Clemens, Kenneth D. Ward, Robert C. Klesges, Christopher M. Vukadinovich and Edwin D. Cantler
Adequate calcium intake is integral to bone health as well as for optimal athletic performance. This study was conducted to investigate: (a) food sources of calcium in a sample of collegiate athletes, (b) gender and/or ethnic differences in food sources of calcium, and (c) whether athletes that derive less of their calcium intake from dairy sources increase their calcium intake from supplements or other food sources. Participants were African-American and Euro-American NCAA Division 1-A athletes. Eighty-five men and 59 women participated. Calcium intake for the previous 7-day period was assessed with a brief calcium screen.
Men consumed significantly more calcium than women (1,354 vs. 898 mg/day), with female cross-country runners exhibiting the lowest average intake (605 mg/day). Both men and women obtained the majority of their calcium from dairy products and mixed dishes, while men consumed significantly more calcium-fortified foods. Several gender and ethnic interactions for calcium intake from food groups were found. Mean total dairy calcium intake was found to vary according to total calcium intake in men, and supplemental calcium was not used to augment low dairy intakes of calcium in any group.
While African-Americans and Euro-Americans athletes were consuming similar levels of calcium, the female athletes in the sample did not get adequate amounts.
This study examined preservice physical education teachers’ (PPETs’) technopedagogical content knowledge (TPCK) competencies. The participants were 1028 PPETs from 26 major universities representing all seven geographical regions of Turkey. The Technological Pedagogical Content Knowledge Deep- Scale developed by Kabakci Yurdakul et al. (2012) was used to measure TPCK competencies of PPETs. Descriptive statistics, an independent samples t test, and multivariate analysis of variance were used to analyze the data. The results showed that PPETs rated themselves at a high level in self-reported TPCK competencies in terms of the entire scale and its factors (design, exertion, ethics and proficiency). There was no significant main effect for gender (p < .05). Computer/internet-based background (p > .05) and PPETs’ interest in keeping up with the latest PE-related technological developments (p > .05) were significant variables in PPETs’ TPCK competencies. Overall, this study offers some evidence that the use of information and communication technology (ICT) is an important factor affecting PPETs’ TPCK competencies.