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Benno M. Nigg, Edward C. Frederick, Michael R. Hawes and Simon M. Luethi

Pain, discomfort, and/or injuries in tennis can be influenced by the individual movement pattern and the external and/or internal boundary conditions. The influence of external boundary conditions on the occurrence of short-term pain was studied in a prospective study with 229 subjects. The boundary conditions investigated were shoe, temperature, type and length of game and subjective assessment of comfort, sole grip, and lateral stability Pain was reported by 40% of the 171 subjects included in the final analysis. It was frequently reported in the first two playing sessions but less frequently afterward. Discomfort was the dominant type of pain, accounting for 71.6% of all reported cases. The foot was the major site of pain (85%). The boundary conditions influencing pain were found to be the shoe (the more flexible shoe 1 had less pain than the suffer shoe 2), the type of game (competitive more than recreational), and the length of the game (longer playing sessions with more pain). Subjective assessment of comfort, sole grip, and lateral support also showed differences for the pain/no pain groups. Subjects who complained about these aspects were more frequently in the pain groups. The results show that the occurrence of pain in tennis can be influenced by various external boundary conditions.

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Eric E. Wickel

Background:

This study examined associations between sedentary time, physical activity (PA), and executive function among youth participating in the Study of Early Child Care and Youth Development.

Methods:

Sedentary time and PA (light, moderate, vigorous, and moderate-to-vigorous (MVPA)) were objectively assessed at 9 and 15 years, while executive function (inhibition, working memory, and fluid intelligence) were assessed at 15 years. Regression models were used to examine associations.

Results:

Sedentary time at 9 years predicted fluid intelligence at 15 years (B = 0.031), whereas increased sedentary time from 9 to 15 years predicted higher inhibition (B = 0.003), working memory (B = 0.074), and fluid intelligence (B = 0.029). Relatively lower levels of working memory at 15 years were predicted from increased levels of light PA, moderate PA, and MVPA from 9 to 15 years (B = –0.075, –0.293, and –0.173, respectively). At 15 years, inhibition, working memory, and fluid intelligence were significantly associated with sedentary time (B = 0.003, 0.055, and 0.045, respectively).

Conclusions:

Childhood sedentary time and PA may affect executive function at 15 years; however, prospective studies are needed to examine the concurrent change in both sedentary time and PA with executive function.

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Dagfinn Aune, Michael Leitzmann and Lars Johan Vatten

Background:

Physical activity has been hypothesized to reduce the risk of gallbladder disease (gallstones, cholecystitis, cholecystectomy); however, results from epidemiological studies have not always shown statistically significant associations. We conducted a systematic review and meta-analysis to clarify the presence and strength of an association between physical activity and gallbladder disease risk.

Methods:

PubMed and Embase databases were searched for studies of physical activity and gallbladder disease up to 9th of January 2015. Prospective studies reporting relative risk (RR) estimates and 95% confidence intervals (CIs) of gallbladder disease associated with physical activity were included. Summary RRs were estimated using a random effects model.

Results:

Eight studies including 6958 cases and 218,204 participants were included. The summary RR for the highest versus the lowest level of physical activity was 0.75 (95% CI: 0.69–0.81, n = 8) and there was no evidence of heterogeneity, I2 = 0%). In the dose-response analysis the summary relative risk per 20 MET-hours of activity was 0.85 (95% CI: 0.80–0.90, I2 = 0%, n = 2) for leisure-time physical activity, 0.83 (95% CI: 0.76–0.90, I2 = 0%, n = 2) for vigorous physical activity, and 0.86 (95% CI: 0.76–0.98, I2 = 0%, n = 2) for nonvigorous physical activity.

Conclusion:

Our analysis confirms a protective effect of physical activity on risk of gallbladder disease.

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Yuki Kondo, Ryuichi Sawa, Aoi Ebina, Masayo Takada, Hiromi Fujii, Yoko Okuyama, Yuko Tanikawa, Kaoru Souke and Rei Ono

Background:

Physical activity during pregnancy has numerous benefits, but the influence on the duration of labor is unclear. We investigated the influence of habitual physical activity during late pregnancy on the duration of labor, with consideration of previous delivery experience and the stage of labor.

Methods:

This prospective study included 103 women (48 nulliparous, 55 multiparous) in late pregnancy. Habitual physical activity was evaluated using the Baecke physical activity questionnaire (BQ). Women were divided into a high activity group (HA) and a low activity group (LA) based on their median total BQ score. Data pertaining to the duration of labor were obtained from the birth records after delivery.

Results:

In multiparous women, the duration of the second stage of labor was significantly shorter in the HA group than in the LA group [median (range): HA, 11 min (1–102 min); LA, 20 min (4–175 min); P < .05]. The significant difference persisted after adjusting for confounding variables (standardized β = –0.34; P = .01). In nulliparous women, there were no significant differences in duration of labor between groups.

Conclusions:

Higher physical activity in multiparous women during late pregnancy might positively influence the duration of the second stage of labor.

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Eileen K. Nehme, Adriana Pérez, Nalini Ranjit, Benjamin C. Amick III and Harold W. Kohl III

Background:

This quasi-experimental study assessed the effects of new workplace showers on physical activity behaviors in a sample of downtown employees in Austin, TX.

Methods:

The study design was quasi-experimental with 2 comparison groups. Data were collected via internet-based surveys before and 4 months after shower installation at 1 worksite. Differences across study groups in the ranks of change in past-week minutes of physical activity from baseline to follow-up were assessed. Adjusted odds ratios and 95% confidence intervals for reporting an increase of ≥10 min past-week physical activity and workday physical activity among those with new showers and existing showers relative to those with no showers were also assessed.

Results:

No significant differences in changes in physical activity from baseline to follow-up across study groups were found. One-quarter of participants with new workplace showers and 46.9% of those with existing workplace showers at baseline reported ever using the showers.

Conclusions:

This prospective study did not find significant changes in employee physical activity 4 months after installation of worksite showers. Worksite shower users were highly active at baseline, suggesting a possible early adopter effect, with potential for diffusion. Future studies may benefit from longer exposure times and larger samples.

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Louis Passfield and James G. Hopker

This paper explores the notion that the availability and analysis of large data sets have the capacity to improve practice and change the nature of science in the sport and exercise setting. The increasing use of data and information technology in sport is giving rise to this change. Web sites hold large data repositories, and the development of wearable technology, mobile phone applications, and related instruments for monitoring physical activity, training, and competition provide large data sets of extensive and detailed measurements. Innovative approaches conceived to more fully exploit these large data sets could provide a basis for more objective evaluation of coaching strategies and new approaches to how science is conducted. An emerging discipline, sports analytics, could help overcome some of the challenges involved in obtaining knowledge and wisdom from these large data sets. Examples of where large data sets have been analyzed, to evaluate the career development of elite cyclists and to characterize and optimize the training load of well-trained runners, are discussed. Careful verification of large data sets is time consuming and imperative before useful conclusions can be drawn. Consequently, it is recommended that prospective studies be preferred over retrospective analyses of data. It is concluded that rigorous analysis of large data sets could enhance our knowledge in the sport and exercise sciences, inform competitive strategies, and allow innovative new research and findings.

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Inacio C. M. da Silva, Valerie L. C. Payne, Adriano Akira Hino, Andrea Ramirez Varela, Rodrigo S. Reis, Ulf Ekelund and Pedro C. Hallal

Background:

The aim of this study was to review the evidence to date on the association between physical activity and safety from crime.

Methods:

Articles with adult populations of 500+ participants investigating the association between physical activity and safety from crime were included. A methodological quality assessment was conducted using an adapted version of the Downs and Black checklist.

Results:

The literature search identified 15,864 articles. After assessment of titles, abstracts and full-texts, 89 articles were included. Most articles (84.3%) were derived from high-income countries and only 3 prospective articles were identified. Articles presented high methodological quality. In 38 articles (42.7%), at least one statistically significant association in the expected direction was reported (ie, safety from crime was positively associated with physical activity). Nine articles (10.1%) found an association in the unexpected direction and 42 (47.2%) did not find statistically significant associations. The results did not change when we analyzed articles separately by sex, age, type of measurement, or domains of physical activity evaluated.

Conclusions:

The current evidence, mostly based on cross-sectional studies, suggests a lack of association between physical activity and safety from crime. Prospective studies and natural experiments are needed, particularly in areas with wide crime variability.

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Sarah Kozey Keadle, Shirley Bluethmann, Charles E. Matthews, Barry I. Graubard and Frank M. Perna

Background:

This paper tested whether a physical activity index (PAI) that integrates PA-related behaviors (ie, moderate-to-vigorous physical activity [MVPA] and TV viewing) and performance measures (ie, cardiorespiratory fitness and muscle strength) improves prediction of health status.

Methods:

Participants were a nationally representative sample of US adults from 2011 to 2012 NHANES. Dependent variables (self-reported health status, multimorbidity, functional limitations, and metabolic syndrome) were dichotomized. Wald-F tests tested whether the model with all PAI components had statistically significantly higher area under the curve (AUC) values than the models with behavior or performance scores alone, adjusting for covariates and complex survey design.

Results:

The AUC (95% CI) for PAI in relation to health status was 0.72 (0.68, 0.76), and PAI-AUC for multimorbidity was 0.72 (0.69, 0.75), which were significantly higher than the behavior or performance scores alone. For functional limitations, the PAI AUC was 0.71 (0.67, 0.74), significantly higher than performance, but not behavior scores, while the PAI AUC for metabolic syndrome was 0.69 (0.66, 0.73), higher than behavior but not performance scores.

Conclusions:

These results provide empirical support that an integrated PAI may improve prediction of health and disease. Future research should examine the clinical utility of a PAI and verify these findings in prospective studies.

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James M. Pivarnik, Christopher P. Connolly, Mallory R. Marshall and Rebecca A. Schlaff

Previous research clearly indicates that exercise training decreases during pregnancy, even among the fittest of women. Despite this, women are typically able to resume their prepregnancy exercise routines soon after delivery, and in some instances, their postpartum performances are better than previously experienced. While anecdotal reports are common, there does not appear to be significant research data to explain this phenomenon. In this review, we explore possible physiologic explanations for heightened postpartum exercise performance, such as pregnancy related changes in aerobic fitness, lactate threshold, flexibility, and musculoskeletal fitness. At this time, limited data do not appear to support an ergogenic role for these variables. Another consideration is a positive change in a woman’s psyche or perceptions toward her athletic abilities as a result of her pregnancy and delivery. While this concept is theoretically possible and may have scientific merit, data are sparse. What is clear is that an increasing number of women are maintaining their physical activity and exercise routines during pregnancy, with many able to return to competition soon after delivery. Well-designed studies are needed to further explore the relationships among physiologic and psychological variables and postpartum exercise performance. Ideally, these studies should be prospective (studying women prepregnancy through the postpartum period) and include diverse samples of women with regard to activity type and fitness level.

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Laura Capranica and Mindy L. Millard-Stafford

A prevailing theory (and practical application) is that elite performance requires early childhood skill development and training across various domains, including sport. Debate continues whether children specializing early (ie, training/competition in a single sport) have true advantage compared with those who sample various sports early and specialize in a single sport later (adolescence). Retrospective data and case studies suggest either model yields elite status depending upon the sport category (ie, situational: ball games, martial arts, fencing; quantitative: track and feld, swimming, skiing; or qualitative: gymnastics, diving, figure skating). However, potential risks of early specialization include greater attrition and adverse physical/emotional health outcomes. With the advent of the IOC Youth Olympic Games, increased emphasis on global youth competition has unknown implications but also represents a potential platform for investigation. Modification of youth competition formats should be based upon multidisciplinary research on psycho-physiological responses, and technical-tactical behaviors during competition. The assumption that a simple scaled-down approach of adult competitions facilitates the development of technical/tactical skills of youth athletes is not necessarily substantiated with field-based research. Relatively little evidence exists regarding the long-term effects of rigorous training and competitive schedules on children in specific sports. It is clear that more prospective studies are needed to understand the training dose that optimally develops adaptations in youth without inducing dropout, overtraining syndrome, and/or injury. Such an approach should be sport specific as well as gender based. Until such evidence exists, coaches and sport administrators will continue to rely upon their sport-specific dogma to influence programmatic development of our most vulnerable population.