Research Quarterly for Exercise and Sport最新文献

Purpose: The aim of this study was fourfold: (1) to quantify acceleration, velocity, and phase overlap for each phase of the stroke cycle (SC) during 200 m front crawl; (2) for each variable, to identify any differences between the four SC phases; (3) to investigate changes in variables during the 200 m; (4) to explore any association between performance and each variable. Methods: Ten swimmers performed a 200 m maximum swim. Four SCs were analyzed, one for each 50 m, using three-dimensional methods. Each SC was split into four phases: entry, pull, push, and recovery. Center of mass (CM) acceleration; maximum, minimum, and average CM velocity; phase duration, and, overlap of a phase of one arm with each phase of the opposite arm were calculated. Results and Conclusion: Phase velocities were positively correlated with performance and decreased during the 200 m. The acceleration data showed high within and between-swimmer variability. When the entry of one arm overlapped with the pull, and sometimes push, phase of the opposite arm, it was propulsive for the whole body. The pull was the slowest phase and overlapped predominantly with the opposite arm's recovery. The push phase was often propulsive for the whole body, regardless of the overlaps with the other arm, and together with the entry were the fastest phases. The recovery of each arm was mostly resistive for the whole body, except the short period of overlap with the opposite arm's push phase.

Purpose: Midlife adults have been estimated to spend over half of their waking time engaging in sedentary behavior, and greater sedentary behavior has been associated with a reduced likelihood of successful aging. Moreover, more than one-quarter of midlife adults report chronic pain, and there is reason to believe that pain may contribute to sedentary behavior among this population. The goal of these analyses was to test associations between self-reported increases in pain during activity and subsequent sedentary behavior among a sample of midlife adults with chronic pain. Methods: Participants included 200 midlife adults (age 50-64) who reported chronic pain and completed an online prospective survey. Activity-induced pain was assessed at baseline and total time spent engaging in sedentary behavior was assessed at baseline, 1-week, and 4-week follow-up assessments. Results: Activity-induced pain predicted greater sedentary behavior at 1-week (p < .05) and 4-week (p < .01) follow-up assessments, even after controlling for chronic pain intensity and baseline sedentary behavior. Conclusions: Activity-induced pain may represent an important mechanism underlying sedentary behavior among midlife adults with chronic pain, and programs designed to reduce sedentary behavior among this population may benefit from tailoring to account for the antithetical influence of activity-induced pain. Indeed, the current findings suggest that mitigating the extent to which pain increases during activity may be more important than reducing overall pain intensity when attempting to decrease sedentary behavior among this population. This and future work have the potential to inform the refinement of tailored interventions.

Purpose: This study investigated acute workload (wAW), chronic workload (wCW), acute: chronic workload ratio (wACWR), training monotony (wTM), perceived load training strain indicators (wTS), and countermove- ment jump (CMJ) as indicators of wellness in one season and defined weekly variations. In addition, we analyzed the relationships between training load measurements and weekly reports. Methods: 16 elite young wrestlers were monitored daily with individual observations for 46 consecutive weeks throughout the season. Training load was obtained using the session rating of perceived effort. wSleep, wStress, wFatigue & wMuscle Soreness well-being were monitored daily using the Hooper index. Results: As a result of the analysis, it was found that there is a moderate relationship (r = 0.51, p = .003) between ACWR and w mean load (A.U.) and a high relationship (r = 0.81, p < .001) between monotony and strain. Conclusion: All variables other than ACWR, w mean load, strain, and monotony presented small and statistically insignificant relationships. These results provide coaches and practitioners with new insights into perceived loads and health changes during a season at the elite youth level.

Although physical education teachers generally act as the physical activity champion and promote adherence to whole-school physical activity programs, classroom teachers manage the majority of students' access to movement throughout the school day. Purpose: To support the adoption of a whole-school physical activity program, this study developed an instrument that identifies barriers perceived by classroom teachers related to adopting this type of program in their school. Method: A four-step process provided the conceptual framework for this instrument development (literature review, expert review, quantitative evaluation, and validation). The final validation phase (N = 520 teachers) included two individual analyses to separately evaluate respondents from elementary (K-5) and secondary levels (6-12). Each group was randomly split to run exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) of the models. Results: CFA results support models with adequate fit to the data for barriers for elementary, e.g., (SRMR = 0.0726; Bentler CFI = 0.92.79) and secondary (SRMR = 0.0813; Bentler CFI = 0.9374) teachers for whole-school programming. Conclusion: This instrument can be used by school personnel and researchers to understand perceived barriers for classroom teachers to implement a whole-school physical activity program in their context and then follow up to remove or reduce the barriers.

Purpose: To examine the effects of a 5-week continuous cycling training intervention on electromyographic amplitude (EMG_RMS)- and mechanomyographic amplitude (MMG_RMS)-torque relationships of the vastus lateralis (VL) during a prolonged contraction. Methods: Twenty-four sedentary, young adults performed maximal voluntary contractions (MVCs) and a prolonged isometric trapezoidal contraction at the same absolute 40% MVC for the knee extensors before (PRE) and after training (POST_ABS). Individual b- (slopes) and a-terms (y-intercepts) were calculated from the log-transformed electromyographic amplitude (EMG_RMS)- and mechanomyographic amplitude (MMG_RMS)-torque relationships during the increasing and decreasing segments of the trapezoid. EMG_RMS and MMG_RMS was normalized for the 45-s steady torque segment. Results: At PRE, b-terms for the EMG_RMS-torque relationships during the linearly decreasing segment were greater than the increasing segment (p < .001), and decreased from PRE to POST_ABS (p = .027). a-terms were greater during the linearly increasing than decreasing segment at PRE, while the a-terms for the linearly decreasing segment increased from PRE to POST_ABS (p = .027). For the MMG_RMS-torque relationships, b-terms during the linearly decreasing segment decreased from PRE to POST_ABS (p = .013), while a-terms increased from PRE to POST_ABS when collapsed across segments (p = .022). Steady torque EMG_RMS increased for POST_ABS (p < .001). Conclusion: Although cycling training increased aerobic endurance, incorporating resistance training may benefit athletes/individuals as the alterations in neuromuscular parameters post-training suggest a greater neural cost (EMG_RMS) and mechanical output (MMG_RMS) to complete the same pre-training fatiguing contraction.

Purpose: The aim of the study was to compare bone mineral density (BMD) in the lumbar spine (LS_BMD) and the femoral neck (F_BMD) in male road cyclists (RC n = 39), mountain cyclists (MC n = 30) and controls (C n = 27) and to determine the factors associated with BMD in the same group of participants. Methods: BMD, fat mass (FM) and fat-free mass (FFM) were measured using DXA. Calcium intake (Cal), exercise energy expenditure (EEE) and energy availability (EA) were assessed using self-reported questionnaires. Samples for circulating hormones were also obtained. VO_2max was estimated by a cycloergometric test. Results: After adjustment for body mass, in cyclists LS_BMD (RC 0.98 ± 0.12; MC 0.98 ± 0.10 g/cm²) was significantly lower than in C (1.11 ± 0.10; p < .001), while F_BMD resulted in no significant difference in cyclists compared to C (p = 0.213). EA (kcal/FFM/day) was different in cyclists and in C (p < .05). In C, EEE and EA were positively associated with LS_BMD (R = 0.561, R = 0.656, respectively, p < .01), whereas only EA was associated with F_BMD (R = 0.554, p < .05); a positive association between EA and F_BMD was found in MC (R = 0.464, p < .05). A negative relationship between VO_2max and LS_BMD in RC (R = -0.418, p < .05) and a positive one between EEE and LS_BMD in MC were found (R = 0.605, p < .001). CaI, free testosterone and cortisol were unrelated to BMD. Conclusion: Both the RC and MC had lower LS_BMD than C, whereas no difference was found between the two groups of cyclists. The factors associated with BMD are manifold, vary in relation to the measurement site and are likely different in RC, MC and C.

Purpose: In a rested state, foam rolling has been shown to improve blood flow to the working tissues. When inducing post-activation performance enhancement (PAPE), previous research suggests a longer recovery period between the conditioning activity and performance assessment in weaker participants (back squat <2.0 × body mass). It is possible that a cool-down effect may take place between the conditioning activity and performance assessment for these participants. Therefore, the purpose of this investigation was to determine if foam rolling could help mitigate any cool-down effect to help participants capitalize on PAPE. Methods: Seventeen physically active participants completed baseline jumps followed by rest (control), back squat exercise (heavy squats), rest and foam rolling (FR), and heavy squats followed by foam rolling (combo). VJ performance was assessed three times post-treatment with 2 min between each assessment. Results: VJ height and impulse were greater at baseline than at any other time point across all sessions (p < .001). Impulse for the control and FR sessions were greater than the squats session (p < .015). Impulse for the combo session was less than the FR session (p = .04). Conclusions: Foam rolling did not have a significant impact on attenuating any cool-down effect. In addition, our heavy squats protocol appears to induce too much fatigue that possibly masked the effects of PAPE.

Purpose: Physical activity (PA) has considerable public health benefits. Positive aspects of the interpersonal environment are known to affect PA, yet few studies have investigated whether negative dimensions also influence PA. This study examines the link between changing social network negativity and PA, net of stable confounding characteristics of persons and their environments. Method: Polling respondents in the San Francisco Bay Area over three waves (2015-2018), the UCNets project provides a panel study of social networks and health for two cohorts of adults. Respondents were recruited through stratified random address sampling, and supplemental sampling was conducted through Facebook advertising and referral. With weights, the sample is approximately representative of Californians aged 21-30 and 50-70. Personal social networks were measured using multiple name-generating questions. Fixed effects ordered logistic regression models provide parameter estimates. Results: Younger adults experience significant decreases in PA when network negativity increases, while changes in other network characteristics (e.g. support, size) did not significantly predict changes in PA. No corresponding association was found for older adults. Results are net of baseline covariate levels, stable social and individual differences, and select time-varying characteristics of persons and their environments. Conclusion: Leveraging longitudinal data from two cohorts of adults, this study extends understanding on interpersonal environments and PA by considering the social costs embedded in social networks. This is the first study to investigate how changes in network negativity pattern PA change. Interventions that help young adults resolve or manage interpersonal conflicts may have the benefit of helping to promote healthy lifestyle choices.