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Benjamin James and David Collins

A qualitative investigation was conducted to identify sources of stress and the self-presentational mechanism that may underpin them during competition. Twenty athletes described factors they perceived as stressful during competition. Content analysis revealed eight general sources of stress, including significant others, competitive anxiety and doubts, perceived readiness, and the nature of the competition (e.g., importance). Two thirds (67.3%) of all stress sources appeared to heighten the athletes’ need to present themselves in a favorable way to the audience. Factors that increased perceived likelihood of poor personal performance lowered the athletes’ ability to convey a desired image to their audience. Social evaluation and self-presentation was also identified as a general source of stress in its own right. These findings suggest that (a) these athletes were sensitive about the impressions people form of them during competition, and (b) stress responses maybe triggered by factors that primarily influence the self-presentational implications of performance.

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Jill A. Kanaley, Richard A. Boileau, Benjamin H. Massey and James E. Misner

Changes in muscular efficiency as it relates to age were examined during inclined submaximal treadmill walking in 298 boys ages 7–15 years. Furthermore, the changes in efficiency with increased work intensity (67–90% V̇O2max) were studied. Efficiency was expressed as submaximal oxygen consumption (V̇O2) and was calculated mathematically as energy out/energy in = (vertical distance) (wt of subject)/(V̇O2 L • min−1) (kcal equivalent). Efficiency, calculated mathematically, was found to significantly increase (p<.01) with age, with the younger children (<9 yrs) being less efficient than the older children (13–15 yrs). These values ranged from 12.8% for the youngest boys (<9 yrs) to 16.4% for the oldest boys (13–15 yrs). In addition, efficiency significantly increased in a linear fashion (p<.01) during submaximal workloads within each age group. No significant interactions (p>.05) between age and workload were found. These values are lower than gross efficiency values during cycling previously reported in the literature for adults; however, they support earlier findings that children increase in efficiency with age and work intensity, regardless if expressed as efficiency or V̇O2 (ml • kg−1 •min−1). These findings suggest that parameters associated with growth and development may influence muscular efficiency with age.

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Jennifer L. Etnier, Benjamin A. Sibley, Jeremy Pomeroy and James C. Kao

Research suggests that there are differences in response time (RespT) as a function of age but that aerobic fitness might have a facilitatory effect on RespT. This study was designed to examine this relationship while addressing methodological issues from past research. Men from 3 age groups completed speeded tasks, a physical activity questionnaire, and an aerobic-fitness test. Results indicated that age has a negative impact on RespT (specifically premotor time and movement time). The interaction of aerobic fitness by age was also a significant predictor of RespT (specifically movement time) such that aerobic fitness was positively related to speed of performance for older participants. It is concluded that aerobic fitness might serve a preservative function for speeded tasks in older adults.

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Constantine P. Nicolozakes, Daniel K. Schneider, Benjamin D. Roewer, James R. Borchers and Timothy E. Hewett

Context: The functional movement screen (FMS™) is used to identify movement asymmetries and deficiencies. While obesity has been reported to impede movement, the correlation between body mass index (BMI), body fat percentage (BF%), and FMS™ in athletes is unknown. Objective: To determine if there is a relationship between BMI, BF%, and FMS™ scores in a sample of National Collegiate Athletic Association Division I football athletes. Design: Cross-sectional study. Setting: Biodynamics laboratory. Participants: A total of 38 male freshman football players (18.0 [0.7] y, 185.3 [5.5] cm, and 103.9 [20.3] kg). Interventions: Height, weight, and BF% were collected, and subjects underwent the FMS™ conducted by a certified athletic trainer. Main Outcome Measures: The dependent variables were BMI, BF%, composite FMS™ score, and 7 individual FMS™ test scores. Subjects were grouped as normal BMI (BMI < 30 kg/m2) or obese (BMI ≥ 30 kg/m2). A composite FMS™ score of ≤14 and an individual FMS™ score of ≤1 were classified as cutoffs for poor movement performance. Results: A negative correlation between composite FMS™ score and BMI approached significance (P = .07, ρ = .296). A negative correlation between composite FMS™ score and BF% was significant (P = .01, ρ = −.449). There was a significant difference in the number of obese subjects scoring below the composite FMS™ cutoff (χ 2 = 5.179, P = .02) and the individual FMS™ cutoff on the deep squat (χ 2 = 6.341, P = .01), hurdle step (χ 2 = 9.870, P = .002), and in-line lunge (χ 2 = 5.584, P = .02) when compared with normal BMI subjects. Conclusions: Increased BF% and BMI relate to lower composite FMS™ and individual FMS™ test scores, indicating potentially poor movement patterns in larger National Collegiate Athletic Association football athletes. Future research should focus on examining lower extremity–specific FMS™ tasks individually from composite FMS™ scores.

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Katherine Histen, Julia Arntsen, Lauren L’Hereux, James Heeren, Benjamin Wicki, Sterling Saint, Giselle Aerni, Craig R. Denegar and Michael F. Joseph

Context:

Tendon adapts to load through alterations in its composition and mechanical properties. Mechanical adaptation to increased load often involves increases in cross-sectional area (CSA), stiffness, and modulus. Runners exhibit these adaptations.

Objective:

To determine if runners wearing minimalist shoes had larger and stiffer Achilles tendons (AT) than traditionally shod runners.

Design:

Cross-sectional study of well-trained, traditionally and minimally shod runners.

Setting:

Laboratory assessment of trained runners.

Participants:

23 men (11 traditional, 12 minimalist) and 8 women (6 traditional, 2 minimalist). Runners wearing minimalist shoes had 4.2 ± 1.6 y of training experience in minimalist shoes.

Main Outcome Measures:

The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force-elongation curve and its derivatives.

Results:

Minimalist runners had a greater CSA: mean difference (MD) = 9.2 mm2, stiffness (MD = 268.1 N/mm), and modulus (MD = 202.9 MPa). ATs of minimalist runners experienced greater stress (MD 8.6 N/mm2) during maximal voluntary isometric contraction of the plantar-flexor muscles due to greater force of contraction (MD 798.9 N).

Conclusion:

The AT in minimalist runners adapts by increasing size, stiffness, and modulus, which is consistent with our understanding of mechanical adaptation of tendon to increased loading. Increased stress to the AT likely requires a slow transition to minimalist running to allow the AT to adapt without evidence of injury.