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Napasakorn Chuensiri, Hirofumi Tanaka and Daroonwan Suksom

Purpose:

To determine the acute effects of high-intensity intermittent exercise (HIIE) on vascular function.

Methods:

Lean (n = 18, BMI = 17.1 ± 0.7) and obese (n = 17, BMI = 25.4 ± 0.8) prepubescent boys aged 10.2 ± 0.2 years were studied. HIIE consisted of 8 sets of 20 s of cycle ergometry at 100, 130, and 170% of VO2peak alternating with 10 s of rests.

Results:

The obese group had higher (p < .05) body mass, BMI, body fat percentage, waist-hip ratio than the lean group. Carotid artery wall thickness and arterial stiffness as assessed by brachial-ankle pulse wave velocity (baPWV) were greater in the obese than in the lean group (p < .05). Brachial artery flow-mediated dilation (FMD) was not different between the groups. Total energy expenditure increased gradually as the exercise intensity increased in both groups (p < .05). The obese group had significantly greater total energy expenditure in all three HIIE intensities than the lean group. FMD tended to be higher and baPWV lower as the exercise intensity increased in both groups. Only the HIIE at 170% demonstrated greater FMD compared with the baseline in both groups. baPWV decreased significantly after HIIE at 130 and 170% VO2peak in both groups.

Conclusion:

Supramaximal HIIE can be a feasible exercise modality for improving vascular function in obese prepubescent boys. Future exercise intervention studies are warranted.

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David Ogilvie, Billie Giles-Corti, Paula Hooper, Lin Yang and Fiona Bull

Modifying the built environment is increasingly recommended as a means of increasing physical activity, but there is currently little evidence from intervention studies to support this approach. From a discussion of 3 natural experiments in this area (RESIDE, iConnect, and Commuting and Health in Cambridge), several common lessons emerged. First, researchers should anticipate delays in the implementation of interventions that are outside their control, and research funders need to exercise a degree of flexibility to accommodate changing research timetables. Second, new built environments develop and evolve over time, and so do their effects on human behavior. Study designs and exposure measures should take account of this, and long term outcomes should be measured wherever possible to allow for potential sleeper, snowball, or threshold effects emerging over time. Third, it may be difficult to identify suitable control areas for a conventional parallel-group intervention–control design, and it may be necessary to draw on other study designs to provide a counterfactual comparison. Fourth, the effort and cost required to recruit, retain and obtain repeated measurements from participants over a period of years should not be underestimated. Finally, comprehensive process evaluation measures may be required to assess the level and quality of interventions.

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Thomas I. Gee, Duncan N. French, Karl C. Gibbon and Kevin G. Thompson

Purpose:

This study investigated the pacing strategy adopted and the consistency of performance and related physiological parameters across three 2000-m rowing-ergometer tests.

Methods:

Fourteen male well-trained rowers took part in the study. Each participant performed three 2000-m rowing-ergometer tests interspersed by 3–7 d. Throughout the trials, respiratory exchange and heart rate were recorded and power output and stroke rate were analyzed over each 500 m of the test. At the completion of the trial, assessments of blood lactate and rating of perceived exertion were measured.

Results:

Ergometer performance was unchanged across the 3 trials; however, pacing strategy changed from trial 1, which featured a higher starting power output and more progressive decrease in power, to trials 2 and 3, which were characterized by a more conservative start and an end spurt with increased power output during the final 500 m. Mean typical error (TE; %) across the three 2000-m trials was 2.4%, and variability was low to moderate for all assessed physiological variables (TE range = 1.4−5.1%) with the exception of peak lactate (TE = 11.5%).

Conclusions:

Performance and physiological responses during 2000-m rowing ergometry were found to be consistent over 3 trials. The variations observed in pacing strategy between trial 1 and trials 2 and 3 suggest that a habituation trial is required before an intervention study and that participants move from a positive to a reverse-J-shaped strategy, which may partly explain conflicting reports in the pacing strategy exhibited during 2000-m rowing-ergometer trials.

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Stephen Seiler and Øystein Sylta

The purpose of this study was to compare physiological responses and perceived exertion among well-trained cyclists (n = 63) performing 3 different high-intensity interval-training (HIIT) prescriptions differing in work-bout duration and accumulated duration but all prescribed with maximal session effort. Subjects (male, mean ± SD 38 ± 8 y, VO2peak 62 ± 6 mL · kg–1 · min–1) completed up to 24 HIIT sessions over 12 wk as part of a training-intervention study. Sessions were prescribed as 4 × 16, 4 × 8, or 4 × 4 min with 2-min recovery periods (8 sessions of each prescription, balanced over time). Power output, HR, and RPE were collected during and after each work bout. Session RPE was reported after each session. Blood lactate samples were collected throughout the 12 wk. Physiological and perceptual responses during >1400 training sessions were analyzed. HIIT sessions were performed at 95% ± 5%, 106% ± 5%, and 117% ± 6% of 40-min time-trial power during 4 × 16-, 4 × 8-, and 4 × 4-min sessions, respectively, with peak HR in each work bout averaging 89% ± 2%, 91% ± 2%, and 94% ± 2% HRpeak. Blood lactate concentrations were 4.7 ± 1.6, 9.2 ± 2.4, and 12.7 ± 2.7 mmol/L. Despite the common prescription of maximal session effort, RPE and sRPE increased with decreasing accumulated work duration (AWD), tracking relative HR. Only 8% of 4 × 16-min sessions reached RPE 19–20, vs 61% of 4 × 4-min sessions. The authors conclude that within the HIIT duration range, performing at “maximal session effort” over a reduced AWD is associated with higher perceived exertion both acutely and postexercise. This may have important implications for HIIT prescription choices.

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Sarah Kozey-Keadle, John Staudenmayer, Amanda Libertine, Marianna Mavilia, Kate Lyden, Barry Braun and Patty Freedson

Background:

Individuals may compensate for exercise training by modifying nonexercise behavior (ie, increase sedentary time (ST) and decrease nonexercise physical activity [NEPA]).

Purpose:

To compare ST and NEPA during a 12-week exercise training and/or lifestyle intervention.

Methods:

Fifty-seven overweight/obese participants (19 M/39 F) completed the study (mean ± SD; age 43.6 ± 9.9 y, BMI 35.1 ± 4.6 kg/m2). There were no between-group differences in activity levels at baseline. Four-arm quasi-experimental intervention study 1) EX: exercise 5 days per week at a moderate intensity (40% to 65% VO2peak) 2) rST: reduce ST and increase NEPA, 3) EX-rST: combination of EX and rST and 4) CON: maintain habitual behavior.

Results:

For the EX group, ST did not decrease significantly (mean ((95% confidence interval) 0.48 (–2.2 to 3.1)% and there was no changes in NEPA at week-12 compared with baseline. The changes were variable, with approximately 50% of participants increasing ST and decreasing NEPA. The rST group decreased ST (–4.8 (0.8 to 7.9)% and increased NEPA. EX-rST significantly decreased ST (–5.1 (–2.2 to 7.9)% and increased time in NEPA at week-12 compared with baseline. The control group increased ST by 4.3 (0.8 to 7.9)%.

Conclusions:

Changes in nonexercise ST and NEPA are variable among participants in an exercise-training program, with nearly half decreasing NEPA compared with baseline. Interventions targeting multiple behaviors (ST and NEPA) may effectively reduce compensation and increase daily activity.

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Lukas D. Linde, Jessica Archibald, Eve C. Lampert and John Z. Srbely

Context: Females suffer 4 to 6 times more noncontact anterior cruciate ligament (ACL) injuries than males due to neuromuscular control deficits of the hip musculature leading to increases in hip adduction angle, knee abduction angle, and knee abduction moment during dynamic tasks such as single-leg squats. Lateral trunk displacement has been further related to ACL injury risk in females, leading to the incorporation of core strength/stability exercises in ACL preventative training programs. However, the direct mechanism relating lateral trunk displacement and lower limb ACL risk factors is not well established. Objective: To assess the relationship between lateral trunk displacement and lower limb measures of ACL injury risk by altering trunk control through abdominal activation techniques during single-leg squats in healthy females. Design: Interventional study setting: movement and posture laboratory. Participants: A total of 13 healthy females (21.3 [0.88] y, 1.68 [0.07] m, and 58.27 [5.46] kg). Intervention: Trunk position and lower limb kinematics were recorded using an optoelectric motion capture system during single-leg squats under differing conditions of abdominal muscle activation (abdominal hollowing, abdominal bracing, and control), confirmed using surface electromyography. Main Outcome Measures: Lateral trunk displacement, peak hip adduction angle, peak knee abduction angle/moment, and average muscle activity from bilateral internal oblique, external oblique, and erector spinae muscles. Results: No differences were observed for peak lateral trunk displacement, peak hip adduction angle, or peak knee abduction angle/moment. Abdominal hollowing and bracing elicited greater muscle activation than the control condition, and bracing was greater than hollowing in 4 of 6 muscles recorded. Conclusion: The lack of reduction in trunk, hip, and knee measures of ACL injury risk during abdominal hollowing and bracing suggests that these techniques alone may provide minimal benefit in ACL injury prevention training.

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Zachary K. Winkelmann, Ethan J. Roberts and Kenneth E. Games

Context: Hamstring inflexibility is typically treated using therapeutic massage, stretching, and soft tissue mobilization. An alternative intervention is deep oscillation therapy (DOT). Currently, there is a lack of evidence to support DOT’s effectiveness to improve flexibility. Objective: To explore the effectiveness of DOT to improve hamstring flexibility. Design: Randomized single-cohort design. Setting: Research laboratory. Participants: Twenty-nine healthy, physically active individuals (self-reported activity of a minimum 200 min/wk). Interventions: All participants received a single session of DOT with randomization of the participant’s leg for the intervention. The DOT intervention parameters included a 1∶1 mode and 70% to 80% dosage at various frequencies for 28 minutes. Hamstring flexibility was assessed using passive straight leg raise for hip flexion using a digital inclinometer. Patient-reported outcomes were evaluated using the Copenhagen Hip and Groin Outcome Score and the Global Rating of Change (GRoC). Main Outcome Measure: The independent variable was time (pre and post). The dependent variables included passive straight leg raise, the GRoC, and the participant’s perceptions of the intervention. Statistical analyses included a dependent t test and a Pearson correlation. Results: Participants reported no issues with sport, activities of daily living, or quality of life prior to beginning the intervention study on the Copenhagen Hip and Groin Outcome Score. Passive straight leg raise significantly improved post-DOT (95% confidence interval, 4.48°–7.85°, P < .001) with a mean difference of 6.17 ± 4.42° (pre-DOT = 75.43 ± 21.82° and post-DOT = 81.60 ± 23.17°). A significant moderate positive correlation was identified (r = .439, P = .02) among all participants between the GRoC and the mean change score of hamstring flexibility. Participants believed that the intervention improved their hamstring flexibility (5.41 ± 1.02 points) and was relaxing (6.21 ± 0.86). Conclusions: DOT is an effective intervention to increase hamstring flexibility.

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Nili Steinberg, Roger Adams, Oren Tirosh, Janet Karin and Gordon Waddington

Context: Ankle sprains are common among adolescent ballet dancers and may be attributed to inadequate ankle proprioception. Thus, a short period of training utilizing proprioceptive activities requires evaluation. Objective: To assess training conducted for 3 or 6 weeks on a textured-surface balance board using ankle proprioception scores for ballet dancers with and without chronic ankle instability, and with and without previous ankle sprain (PAS). Design: Intervention study. Setting: The Australian Ballet School. Participants: Forty-two ballet dancers, aged 14–18 years. Interventions: Dancers randomized into 2 groups: group 1 undertook 1 minute of balance board training daily for 3 weeks; group 2 undertook the same training for 6 weeks. Main Outcome Measures: Preintervention, Cumberland Ankle Instability Tool questionnaire data were collected, and PAS during the last 2 years was reported. Active ankle inversion movement discrimination ability was tested immediately pre and post intervention and at 3 and 4 weeks. Results: Ankle discrimination acuity scores improved over time for both groups, with a performance decline associated with the early cessation of training for group 1 (P = .04). While dancers with PAS had significantly worse scores at the first test, before balance board training began (P < .01), no significant differences in scores at any test occasion were found between dancers with and without chronic ankle instability. A significantly faster rate of improvement in ankle discrimination ability score over the 4 test occasions was found for dancers with PAS (P = .002). Conclusions: Three weeks of textured balance board training improved the ankle discrimination ability of ballet dancers regardless of their reported level of chronic ankle instability and at a faster rate for dancers with PAS. Previous ankle sprain was associated with a lower level of ankle discrimination ability; however, following 3 weeks of balance board training, previously injured dancers had significantly improved their ankle discrimination acuity scores.

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Julien Tripette, Haruka Murakami, Hidemi Hara, Ryoko Kawakami, Yuko Gando, Harumi Ohno, Nobuyuki Miyatake and Motohiko Miyachi

manipulate exercise perception and increase PA in inactive people. However, Judice et al. ( 2013 ) did not observe any increase in PA in subjects supplemented with caffeine during a 5-day intervention study conducted under free-living conditions. These studies ( Judice et al., 2013 ; Schrader et al., 2013

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Haichun Sun and Tan Zhang

experiences, they tend to lose motivation in physical education ( Cothran & Ennis, 1999 ). Guided by social constructivist approaches, Ennis et al. conducted a series of curriculum intervention studies in physical education. In the following sections, we review some of the studies to illustrate the