SciCombinator

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Journal: Medicine and science in sports and exercise

68

To examine the associations of birth weight with ability in school sports in adolescence and participation in leisure-time physical activity (LTPA) across adulthood, and to investigate whether associations between birth weight and LTPA change with age.

Concepts: Biology, Sports equipment

64

To determine the effects of heat-acclimatization on performance and pacing during outdoor cycling time-trials (TT, 43.4km) in the heat.

Concepts: Effect, Effects unit

57

PURPOSE: Running and other strenuous sports activities are purported to increase osteoarthritis (OA) risk, more so than walking and less-strenuous activities. Analyses were therefore performed to test whether running, walking, and other exercise affect OA and hip replacement risk, and to assess BMI’s role in mediating these relationships. METHODS: Proportional hazards analyses of patients' report of having physician-diagnosed OA and hip replacement vs. exercise energy expenditure (metabolic equivalents, METs). RESULTS: 74,752 runners reported 2004 OA and 259 hip replacements during 7.1-year follow-up, while the 14,625 walkers reported 696 OA and 114 hip replacements over 5.7 years. Compared to running <1.8 METhr/d, the risks for OA and hip replacement decreased: 1) 18.1% (P=0.01) and 35.1% (P=0.03), respectively, for 1.8 to 3.6 METhr/d run; 2) 16.1% (P=0.03) and 50.4% (P=0.002), respectively, for 3.6 to 5.4 METhr/d run; and 3) 15.6% (P=0.02) and 38.5% (P=0.01), respectively, for ≥5.4 METhr/d run, suggesting that the risk reduction mostly occurred by 1.8 METhr/d. Baseline BMI was strongly associated with both OA (5.0% increase per kg/m, P=2x10) and hip replacement risks (9.8% increase per kg/m, P=4.8x10), and adjustment for BMI substantially diminished the risk reduction from running ≥1.8 METhr/d for OA (from 16.5%, P=0.01 to 8.6%, P=0.21) and hip replacement (from 40.4%, P=0.005 to 28.5%, P=0.07). The reductions in OA and hip replacement risk by exceeding 1.8 METhr/d did not differ significantly between runners and walkers. Other (non-running) exercise increased the risk of OA by 2.4% (P=0.009) and hip replacement by 5.0% per METhr/d (P=0.02), independent of BMI. CONCLUSIONS: Whereas other exercise increased OA and hip replacement risk, running significantly reduced their risk due, in part, to running's association with lower BMI.

Concepts: Risk, Hip replacement, Running, Walking, Hazard, Indian Reductions, Replacements

48

Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques employed by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated.

Concepts: Running

44

The psychobiological model of endurance performance proposes that perception of effort is the ultimate determinant of endurance performance. Therefore, any physiological or psychological factor affecting perception of effort will affect endurance performance. Accordingly this novel study investigated the effects of a frequently used psychological strategy, motivational self-talk (ST), on rating of perceived exertion (RPE) and endurance performance.

Concepts: Psychology, Effect, Affect, Cognition, Educational psychology, Perception, Mind, Experimental psychology

42

Sitting time (ST) is associated with cardiovascular disease risk factors whereas breaking ST has been reported to be beneficial for reducing cardiovascular risk.

Concepts: Atherosclerosis, Blood vessel, Cardiovascular disease, Asymmetric dimethylarginine

40

To explore whether compensatory responses to acute energy deficits induced by exercise or diet differ by sex.

Concepts: Obesity

39

There is a lack of consensus regarding the optimal range of carbohydrate (CHO) ingestion rates recommended for endurance athletes.

Concepts: Dose-response relationship

39

Limited regional sweat rate (RSR) data are available for females, with only a small number of sites measured across the body. Similarly, sex differences in sweating concentrate on whole body values, with limited RSR data available.

Concepts: Male, Female, Sexual dimorphism, Gender, Sex, Perspiration, SWEAT

38

PURPOSE: Commencing selected workouts with low muscle glycogen availability augments several markers of training adaptation compared to undertaking the same sessions with normal glycogen content. However, low glycogen availability reduces the capacity to perform high intensity (>85% of peak aerobic power [V˙O2peak]) endurance exercise. We determined whether a low dose of caffeine could partially rescue the reduction in maximal self-selected power output observed when individuals commenced high intensity interval training (HIT) with low (LOW) compared to normal (NORM) glycogen availability. METHODS: Twelve endurance-trained cyclists/triathletes performed four experimental trials using a double-blind Latin square design. Muscle glycogen content was manipulated via exercise-diet interventions so that two experimental trials were commenced with LOW and two with NORM muscle glycogen availability. Sixty minutes prior to an experimental trial, subjects ingested a capsule containing anhydrous caffeine (CAFF; 3 mg·kg body mass) or placebo (PLBO). Instantaneous power output (W) was measured throughout HIT (8 × 5 min bouts at maximum self-selected intensity with 1 min recovery). RESULTS: There were significant main effects for both pre-exercise glycogen content and caffeine ingestion on power output. LOW reduced power output by ∼8% compared to NORM (P < 0.01) whereas caffeine increased power output by 2.8% and 3.5% for NORM and LOW respectively (P < 0.01). CONCLUSIONS: We conclude that caffeine enhanced power output independently of muscle glycogen concentration but could not fully restore power output to levels commensurate with that when subjects commenced exercise with normal glycogen availability. However, the reported increase in power output does provide a likely performance benefit and may provide a means to further enhance the already augmented training response observed when selected sessions are commenced with reduced muscle glycogen availability.

Concepts: Muscle, Physical exercise, English-language films, Caffeine, Exercise physiology, Intensity, High-intensity interval training, Power