Browse

You are looking at 11 - 20 of 382 items for :

  • Sport and Exercise Science/Kinesiology x
  • User-accessible content x
Clear All
Full access

Mohammad Siahpush, Trish D. Levan, Minh N. Nguyen, Brandon L. Grimm, Athena K. Ramos, Tzeyu L. Michaud and Patrik L. Johansson

Background: The mortality benefits of meeting the US federal guidelines for physical activity, which includes recommendations for both aerobic and muscle-strengthening activities, have never been examined among smokers. Our aim was to investigate the association between reporting to meet the guidelines and all-cause, cancer, cardiovascular disease, and respiratory disease mortality among smokers. Methods: We pooled data from the 1998–2009 National Health Interview Survey, which were linked to records in the National Death Index (n = 68,706). Hazard ratios (HR) were computed to estimate the effect of meeting the physical activity guidelines on mortality. Results: Smokers who reported meeting the guidelines for physical activity had 29% lower risk of all-cause mortality (HR: 0.71; 95% confidence interval [CI], 0.62–0.81), 46% lower risk of mortality from cardiovascular disease (HR: 0.54; 95% CI, 0.39–0.76), and 26% lower risk of mortality from cancer (HR: 0.74; 95% CI, 0.59–0.93), compared with those who reported meeting neither the aerobic nor the muscle-strengthening recommendations of the guidelines. Meeting the aerobic recommendation of the guidelines was associated with a 42% decline in that risk (HR: 0.58; 95% CI, 0.44–0.77). Conclusion: Smokers who adhere to physical activity guidelines show a significant reduction in mortality.

Full access

Christina M. Patch, Caterina G. Roman, Terry L. Conway, Ralph B. Taylor, Kavita A. Gavand, Brian E. Saelens, Marc A. Adams, Kelli L. Cain, Jessa K. Engelberg, Lauren Mayes, Scott C. Roesch and James F. Sallis

Background: A common hypothesis is that crime is a major barrier to physical activity, but research does not consistently support this assumption. This article advances research on crime-related safety and physical activity by developing a multilevel conceptual framework and reliable measures applicable across age groups. Methods: Criminologists and physical activity researchers collaborated to develop a conceptual framework. Survey development involved qualitative data collection and resulted in 155 items and 26 scales. Intraclass correlation coefficients (ICCs) were computed to assess test–retest reliability in a subsample of participants (N = 176). Analyses were conducted separately by age groups. Results: Test–retest reliability for most scales (63 of 104 ICCs across 4 age groups) was “excellent” or “good” (ICC ≥ .60) and only 18 ICCs were “poor” (ICC < .40). Reliability varied by age group. Adolescents (aged 12–17 y) had ICCs above the .40 threshold for 21 of 26 scales (81%). Young adults (aged 18–39 y) and middle-aged adults (aged 40–65 y) had ICCs above .40 for 24 (92%) and 23 (88%) scales, respectively. Older adults (aged 66 y and older) had ICCs above .40 for 18 of 26 scales (69%). Conclusions: The conceptual framework and reliable measures can be used to clarify the inconclusive relationships between crime-related safety and physical activity.

Open access

Øyvind Skattebo, Thomas Losnegard and Hans Kristian Stadheim

Purpose: Long-distance cross-country skiers specialize to compete in races >50 km predominantly using double poling (DP). This emphasizes the need for highly developed upper-body endurance capacities and an efficient DP technique. The aim of this study was to investigate potential effects of specialization by comparing physiological capacities and kinematics in DP between long-distance skiers and skiers competing using both techniques (skating/classic) in several competition formats (“all-round skiers”). Methods: Seven male long-distance (32 [6] y, 183 [6] cm, 76 [5] kg) and 6 all-round (25 [3] y, 181 [5] cm, 75 [6] kg) skiers at high international levels conducted submaximal workloads and an incremental test to exhaustion for determination of peak oxygen uptake (VO2peak) and time to exhaustion (TTE) in DP and running. Results: In DP and running maximal tests, TTE showed no difference between groups. However, long-distance skiers had 5–6% lower VO2peak in running (81 [5] vs 85 [3] mL·kg−1·min−1; P = .07) and DP (73 [3] vs 78 [3] mL·kg−1·min−1; P < .01) than all-round skiers. In DP, long-distance skiers displayed lower submaximal O2 cost than all-round skiers (3.8 ± 3.6%; P < .05) without any major differences in cycle times or cyclic patterns of joint angles and center of mass. Lactate concentration over a wide range of speeds (45–85% of VO2peak) did not differ between groups, even though each workload corresponded to a slightly higher percentage of VO2peak for long-distance skiers (effect size: 0.30–0.68). Conclusions: The long-distance skiers displayed lower VO2peak but compensated with lower O2 cost to perform equally with the all-round skiers on a short TTE test in DP. Furthermore, similar submaximal lactate concentration and reduced O2 cost could be beneficial in sustaining high skiing speeds in long-duration competitions.

Open access

Mhairi K. MacLean and Daniel P. Ferris

The authors tested 4 young healthy subjects walking with a powered knee exoskeleton to determine if it could reduce the metabolic cost of locomotion. Subjects walked with a backpack loaded and unloaded, on a treadmill with inclinations of 0° and 15°, and outdoors with varied natural terrain. Participants walked at a self-selected speed (average 1.0 m/s) for all conditions, except incline treadmill walking (average 0.5 m/s). The authors hypothesized that the knee exoskeleton would reduce the metabolic cost of walking uphill and with a load compared with walking without the exoskeleton. The knee exoskeleton reduced metabolic cost by 4.2% in the 15° incline with the backpack load. All other conditions had an increase in metabolic cost when using the knee exoskeleton compared with not using the exoskeleton. There was more variation in metabolic cost over the outdoor walking course with the knee exoskeleton than without it. Our findings indicate that powered assistance at the knee is more likely to decrease the metabolic cost of walking in uphill conditions and during loaded walking rather than in level conditions without a backpack load. Differences in positive mechanical work demand at the knee for varying conditions may explain the differences in metabolic benefit from the exoskeleton.

Full access

Angela Maria Hoyos-Quintero and Herney Andrés García-Perdomo

Objective: To evaluate the relationship between biologico-demographical, sociocultural, and environmental factors and the performance of physical activity in early childhood. Methodology: A systematic search was carried out of the databases MEDLINE, EMBASE, CENTRAL, and LILACS, as well as Google Scholar, Open Grey, ClinicalTrials.gov, DARE, PROSPERO, Health Technology Assessment, and the World Health Organization International Clinical Trials Registry Platform, from their first records to June 2018. The selection criteria were previously defined with respect to population age and article theme. No meta-analyses were carried out due to the heterogeneity of the studies. Results: The percentage of moderate to vigorous physical activity runs between 3% and 47%. Environmental and sociocultural factors were identified as exerting a greater influence on children’s physical activity in early childhood, with the environmental factors being, according to almost all the study authors, the greater of the two. Conclusions: According to the studies included in this research project, the factors identified as associated with moderate to vigorous physical activity are environmental (play in open spaces) and sociocultural (the role of the family and the physical activity of the mother). The evidence is not strong enough to conclude that biologico-demographic factors are significantly influential in the physical activity at this age.

Open access

Sang-Ho Lee, Steven D. Scott, Elizabeth J. Pekas, Jeong-Gi Lee and Song-Young Park

Purpose: Athletes in combat sports undergo rapid changes in body weight prior to competition in order to gain a size advantage over their opponent. However, these large weight changes with concomitant high-intensity exercise training create poor lipid profiles and high levels of oxidative stress, which can be detrimental to health and sport performance. Therefore, the purpose of this study was to investigate the ability of the nutritional supplement octacosanol to combat the physiological detriments that occur in taekwondo players during rapid weight loss with high-intensity exercise training. Methods: A total of 26 male taekwondo players were randomly divided into 2 groups: An experimental group performed a 5% weight-loss and taekwondo training program with 40-mg octacosanol intake (OCT; n = 13) for 6 d, and a control group performed the same weight-loss and taekwondo training program with a placebo (CON; n = 13). Results: There were significant (P < .05) group × time interactions for low-density lipoprotein and triglycerides, which significantly decreased (Δ18 [5] mg/dL and Δ80 [7] mg/dL, respectively), and high-density lipoprotein, which significantly increased (Δ10 [7] mg/dL), in the OCT group compared with the CON group. There were also significant (P < .05) group × time interactions for superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA), with SOD increasing (Δ226 [121] U/gHb) in the OCT group, while GPx decreased (Δ20 [13] U/gHb) and MDA increased (Δ72 [0.04] nmol/mL) in the CON group. Conclusion: These results suggest that octacosanol may be a beneficial supplement to protect against the poor cholesterol levels and oxidative stress that occurs during taekwondo training.

Full access

Ítalo R. Lemes, Rômulo A. Fernandes, Bruna C. Turi-Lynch, Jamile S. Codogno, Luana C. de Morais, Kelly A.K. Koyama and Henrique L. Monteiro

Background: Metabolic syndrome (MetS) is a combination of risk factors for cardiovascular disease and type 2 diabetes mellitus. The prevalence of MetS worldwide is increasing. There is no study investigating the economic burden of MetS, especially in developing countries, on medication-related expenditure. The aim of this study was to investigate the association of medication-related expenditures with MetS and to explore how physical activity (PA) may influence this association. Methods: A total of 620 participants, 50 years or older, randomly selected in the city of Bauru, Brazil. Participants were followed from 2010 to 2014, and data on health care expenditure were collected annually. PA questionnaire was applied at baseline, 2 (2012), and 4 (2014) years later. Results: Mean age was 64.7 (95% confidence interval, 64.1–65.3). MetS was associated with higher medication expenditure related to diseases of the circulatory (P <.01) and endocrine (P <.01) systems. MetS explained 17.2% of medication-related expenditures, whereas PA slightly attenuated this association, explaining 1.1% of all health care costs. Conclusion: This study demonstrates that MetS has a significant burden on health care expenditures among adults, whereas PA seems to affect this phenomenon significantly, but in low magnitude.

Open access

David M. Shaw, Fabrice Merien, Andrea Braakhuis, Daniel Plews, Paul Laursen and Deborah K. Dulson

This study investigated the effect of the racemic β-hydroxybutyrate (βHB) precursor, R,S-1,3-butanediol (BD), on time-trial (TT) performance and tolerability. A repeated-measures, randomized, crossover study was conducted in nine trained male cyclists (age, 26.7 ± 5.2 years; body mass, 69.6 ± 8.4 kg; height, 1.82 ± 0.09 m; body mass index, 21.2 ± 1.5 kg/m2; VO2peak,63.9 ± 2.5 ml·kg−1·min−1; Wmax, 389.3 ± 50.4 W). Participants ingested 0.35 g/kg of BD or placebo 30 min before and 60 min during 85 min of steady-state exercise, which preceded a ∼25- to 35-min TT (i.e., 7 kJ/kg). The ingestion of BD increased blood D-βHB concentration throughout exercise (0.44–0.79 mmol/L) compared with placebo (0.11–0.16 mmol/L; all p < .001), which peaked 1 hr following the TT (1.38 ± 0.35 vs. 0.34 ± 0.24 mmol/L; p < .001). Serum glucose and blood lactate concentrations were not different between trials (all p > .05). BD ingestion increased oxygen consumption and carbon dioxide production after 20 min of steady-state exercise (p = .002 and p = .032, respectively); however, no further effects on cardiorespiratory parameters were observed. Within the BD trial, moderate to severe gastrointestinal symptoms were reported in five participants, and low levels of dizziness, nausea, and euphoria were reported in two participants. However, this had no effect on TT duration (placebo, 28.5 ± 3.6 min; BD, 28.7 ± 3.2 min; p = .62) and average power output (placebo, 290.1 ± 53.7 W; BD, 286.4 ± 45.9 W; p = .50). These results suggest that BD has no benefit for endurance performance.