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Susana Meireles, Neil D. Reeves, Richard K. Jones, Colin R. Smith, Darryl G. Thelen and Ilse Jonkers

Medial knee loading during stair negotiation in individuals with medial knee osteoarthritis has only been reported in terms of joint moments, which may underestimate the knee loading. This study assessed knee contact forces (KCF) and contact pressures during different stair negotiation strategies. Motion analysis was performed in 5 individuals with medial knee osteoarthritis (52.8 [11.0] y) and 8 healthy subjects (51.0 [13.4] y) while ascending and descending a staircase. KCF and contact pressures were calculated using a multibody knee model while performing step-over-step at controlled and self-selected speed, and step-by-step strategies. At controlled speed, individuals with osteoarthritis showed decreased peak KCF during stair ascent but not during stair descent. Osteoarthritis patients showed higher trunk rotations in frontal and sagittal planes than controls. At lower self-selected speed, patients also presented reduced medial KCF during stair descent. While performing step-by-step, medial contact pressures decreased in osteoarthritis patients during stair descent. Osteoarthritis patients reduced their speed and increased trunk flexion and lean angles to reduce KCF during stair ascent. These trunk changes were less safe during stair descent where a reduced speed was more effective. Individuals should be recommended to use step-over-step during stair ascent and step-by-step during stair descent to reduce medial KCF.

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Paige M. Watkins, Elissa Burton and Anne-Marie Hill

Resistance training (RT) can maintain and improve physical and mental health in older adults, but this population has low levels of RT participation. Linking older people participating in RT (i.e., peers) with those who have not may promote and maintain adherence. This qualitative study explored the experience of peers in encouraging RT participation among older adults. Data were collected using focus groups, researcher observations, and semistructured interviews. Thematic analysis was conducted. Older people (n = 8) who engaged in RT prior to recruitment, participated as peers. Each provided peer support for between one and four RT participants for 6 weeks. The peer role was perceived by peers as potentially leading to a relationship which benefitted both parties. Peers reported that helping and supporting others was a positive experience and raised their self-efficacy. Difficulty initiating contact and differing expectations of peers and RT participants were viewed as challenges. Peer mentoring could help promote RT participation among older adults.

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Pamela K. Samra, Amanda L. Rebar, Lynne Parkinson, Jannique G.Z. van Uffelen, Stephanie Schoeppe, Deborah Power, Anthony Schneiders, Corneel Vandelanotte and Stephanie Alley

An understanding of physical activity attitudes, preferences, and experiences in older adults is important for informing interventions. Focus groups were conducted with 46 regionally-based Australian adults aged 65 years and older, who were not currently meeting activity recommendations. Content analysis revealed that participants mainly engaged in incidental activities such as gardening and household chores rather than planned exercise; however, leisure-time walking was also mentioned frequently. Although participants valued the physical and mental health benefits of physical activity, they reported being restricted by poor physical health, extreme weather, and fear of injury. Participants were interested in exercise groups and physical activity programs tailored to their existing physical health. The majority of participants reported preferring to be active with others. The findings from this study are useful in for informing future interventions specifically tailored to the needs of older adults in Australia.

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Michael J. Davies, Bradley Clark, Laura A. Garvican-Lewis, Marijke Welvaert, Christopher J. Gore and Kevin G. Thompson

Purpose: To determine if a series of trials with fraction of inspired oxygen (FiO2) content deception could improve 4000-m cycling time-trial (TT) performance. Methods: A total of 15 trained male cyclists (mean [SD] body mass 74.2 [8.0] kg, peak oxygen uptake 62 [6] mL·kg−1·min−1) completed six 4000-m cycling TTs in a semirandomized order. After a familiarization TT, cyclists were informed in 2 initial trials they were inspiring normoxic air (NORM, FiO2 0.21); however, in 1 trial (deception condition), they inspired hyperoxic air (NORM-DEC, FiO2 0.36). During 2 subsequent TTs, cyclists were informed they were inspiring hyperoxic air (HYPER, FiO2 0.36), but in 1 trial, normoxic air was inspired (HYPER-DEC). In the final TT (NORM-INFORM), the deception was revealed and cyclists were asked to reproduce their best TT performance while inspiring normoxic air. Results: Greater power output and faster performances occurred when cyclists inspired hyperoxic air in both truthful (HYPER) and deceptive (NORM-DEC) trials than NORM (P < .001). However, performance only improved in NORM-INFORM (377 W; 95% confidence interval [CI] 325–429) vs NORM (352 W; 95% CI 299–404; P < .001) when participants (n = 4) completed the trials in the following order: NORM-DEC, NORM, HYPER-DEC, HYPER. Conclusions: Cycling performance improved with acute exposure to hyperoxia. Mechanisms for the improvement were likely physiological; however, improvement in a deception trial suggests an additional placebo effect. Finally, a particular sequence of oxygen deception trials may have built psychophysiological belief in cyclists such that performance improved in a subsequent normoxic trial.

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Bruno Marrier, Alexandre Durguerian, Julien Robineau, Mounir Chennaoui, Fabien Sauvet, Aurélie Servonnet, Julien Piscione, Bertrand Mathieu, Alexis Peeters, Mathieu Lacome, Jean-Benoit Morin and Yann Le Meur

Purpose: Preconditioning strategies are considered opportunities to optimize performance on competition day. Although investigations conducted in rugby players on the effects of a morning preconditioning session have been done, additional work is warranted. The aim of this study was to monitor changes in physical and psychophysiological indicators among international Rugby-7s players after a priming exercise. Methods: In a randomized crossover design, 14 under-18 international Rugby-7s players completed, at 8:00 AM, a preconditioning session consisting of a warm-up followed by small-sided games, accelerations, and 2 × 50-m maximal sprints (Experimental), or no preloading session (Control). After a 2-h break, the players performed a set of six 30-m sprints and a Rugby-7s match. Recovery–stress state and salivary stress-marker levels were assessed before the preloading session (Pre), immediately after the preloading session (Post 1), before the testing session (Post 2), and after the testing session (Post 3). Results: Experimental–Control differences in performance across a repeated-sprint test consisting of six 30-m sprints were very likely trivial (+0.2, ±0.7%, 3/97/1%). During the match, the total distance covered and the frequency of decelerations were possibly lower (small) in Experimental compared with Control. Differences observed in the other parameters were unclear or possibly trivial. At Post 2, the perceived recovery–stress state was improved (small difference) in Experimental compared with Control. No difference in salivary cortisol response was observed, while the preconditioning session induced a higher stimulation of salivary testosterone and α-amylase. Conclusions: The players’ ability to repeat sprints and physical activity in match play did not improve, but their psychophysiological state was positively affected after the present preconditioning session.

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Sasha A. Fleary, Robin Mehl and Claudio Nigg

Background: Health behaviors in childhood and adolescence are implicated in health behaviors and chronic disease risk in adulthood for the majority of the US population. However, little is known about these relationships in Hawaiian youth. This study investigated the extent to which childhood physical activity (PA) and fruit and vegetable consumption behaviors predicted later behaviors across a 10-year period in Hawaiian youth. Methods: Three cohorts of fourth- to sixth-grade students who participated in an elementary after-school program (Fun 5) provided baseline data (Y1—data collected between 2003 and 2007), 5-year (Y5—data collected between 2008 and 2012), and 10-year (Y10—data collected between 2013 and 2017) follow-up surveys. Demographic, PA, and fruit and vegetable consumption measures were completed at all 3 time points. Bivariate and multiple regressions were computed in 2018. Results: Y1 and Y5 behavior predicted PA in young adulthood. For fruit and vegetable consumption, Y1 behavior predicted Y5 behavior but not Y10 behavior, and Y5 behavior predicted Y10 behaviors. Conclusions: Similar to mainland US youth, it is important to address PA and nutrition early in the life span for Hawaiian youth to increase long-term preventive health behaviors and reduce long-term chronic disease risk.

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Samuel D. Muir, Sandun S.M. Silva, Mulu A. Woldegiorgis, Hayley Rider, Denny Meyer and Madawa W. Jayawardana

Background: Despite holding great potential for addressing concerns regarding public health, recent systematic reviews have found effect sizes for interventions targeting physical activity to be small. Before interventions can be improved, the factors influencing outcomes must be identified. This systematic review aimed to identify predictors of success, measured in terms of engagement (eg, involvement duration) and health behavior change (eg, increased step counts), of workplace interventions targeting physical activity. Methods: A structured search of 3 databases (PubMed, PsycINFO, and Web of Science) was conducted to identify articles published between January 2000 and April 2017. For inclusion, articles needed to test a workplace intervention targeting physical activity and perform a quantitative analysis, identifying predictors of engagement or health behavior change. Results: Twenty-two studies were identified for review (median quality score = 70%). Demographic variables (eg, gender, age) were inconsistent predictors of success. However, employees in better health and physically active at baseline were found to have a greater likelihood of success. Conclusions: It appears that achieving successful results among employees at high risk of poor health outcomes remains a significant challenge for interventions. It is hoped that program developers can use this information to create effective interventions particularly for more sedentary employees.

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Breanna E. Studenka and Kodey Myers

Children with autism spectrum disorder (ASD) exhibit impairment in helping someone else with a motor action, which may arise from impairment in selecting and preparing motor responses. Five children with ASD and five typically developing children performed a cooperative motor planning task that required them to reach for, lift, and hand an object (hammer or stick) to a researcher. The response, movement, and grasp time were measured. Children with ASD grasped the object longer on trials where they helped, indicating that the action was planned in sequence versus as a whole (i.e., prior to the onset of movement). The hammer object elicited a quicker response than the stick, suggesting the facilitation of planning by tools with inherent action properties. Finally, the increased helping of children with ASD was not mirrored by changes in the response, movement, or grasp time.

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Lachlan J.G. Mitchell, Ben Rattray, Paul Wu, Philo U. Saunders and David B. Pyne

Purpose: Critical speed (CS) and supra-CS distance capacity (D′) are useful metrics for monitoring changes in swimmers’ physiological and performance capacities. However, the utility of these metrics across a season has not been systematically evaluated in high-level swimmers. Methods: A total of 27 swimmers (mean [SD]: 18 females, age = 19.1 [2.9] y, and 9 males, age = 19.5 [1.9] y) completed the 12 × 25-m swimming test multiple times (4 [3] tests/swimmer) across a 2-y period. Season-best times in all distances for the test stroke were sourced from publicly available databases. Swimmers’ distance speciality was determined as the event with the time closest to world record. Four metrics were calculated from the 12 × 25-m test: CS, D′, peak speed, and drop-off %. Results: Guyatt responsiveness index values were calculated to ascertain the practically relevant sensitivity of each 12 × 25-m metric: CS = 1.5, peak speed = 2.3, D′ = 2.1, and drop-off % = 2.6. These values are modified effect sizes; all are large effects. Bayesian mixed modeling showed substantial between-subjects differences between genders and strokes for each variable but minimal within-subject changes across the season. Drop-off % was lower in 200-m swimmers (14.0% [3.3%]) than in 100-m swimmers (18.1% [4.1%], P = .003, effect size = 1.10). Conclusions: The 12 × 25-m test is best suited to differentiating between swimmers of different strokes and events. Further development is needed to improve its utility in quantifying meaningful changes over a season for individual swimmers.

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Guy C. Wilson, Yorgi Mavros, Lotti Tajouri and Maria Fiatarone Singh

Background: Variations in genotype may contribute to heterogeneity in functional adaptations to exercise. Methods: A systematic search of eight databases was conducted, and 9,696 citations were screened. Results: Eight citations from seven studies measuring 10 single-nucleotide polymorphisms and nine different functional performance test outcomes were included in the review. There was one observational study of physical activity and six experimental studies of aerobic or resistance training. The ACE (D) allele, ACTN3 (RR) genotype, UCP2 (GG) genotype, IL-6-174 (GG) genotype, TNF-α-308 (GG) genotype, and IL-10-1082 (GG) genotype all predicted significantly superior adaptations in at least one functional outcome in older men and women after prescribed exercise or in those with higher levels of physical activity. Conclusion: There is a small amount of evidence that older adults may have better functional outcomes after exercise/physical activity if they have specific alleles related to musculoskeletal function or inflammation. However, more robust trials are needed.