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David Travis Thomas, Laurie Wideman and Cheryl A. Lovelady

Purpose:

To examine the effect of yogurt supplementation pre- and postexercise on changes in body composition in overweight women engaged in a resistance-training program.

Methods:

Participants (age = 36.8 ± 4.8 yr) with a body-mass index of 29.1±2.1 kg/m2 were randomized to yogurt supplement (YOG; n = 15) or isoenergetic sucrose beverage (CONT; n = 14) consumed before and after exercise for 16 wk. Participants were also instructed to reduce energy intake daily (–1,046 kJ) during the study. Body composition was assessed by dual-energy X-ray absorptiometry, waist circumference, and sagittal diameter. Strength was measured with 1-repetition maximum. Dietary recalls were obtained by a multipass approach using Nutrition Data System software. Insulin-like growth factor-1 and insulin-like growth-factor-binding protein-3 were measured with ELISA.

Results:

Significant weight losses of 2.6 ± 4.5 kg (YOG) and 1.2 ± 2.5 kg (CONT) were observed. Total lean weight increased significantly over time in both YOG (0.8 ± 1.2 kg) and CONT (1.1 ± 0.9 kg). Significant reductions in total fat (YOG = 3.4 ± 4.1 kg vs. CONT = 2.3 ± 2.4 kg) were observed over time. Waist circumference, sagittal diameter, and trunk fat decreased significantly over time without group differences. Both groups significantly decreased energy intake while maintaining protein intake. Strength significantly increased over time in both groups. No changes over time or between groups were observed in hormone levels.

Conclusions:

These data suggest that yogurt supplementation offered no added benefit for increasing lean mass when combined with resistance training and modest energy restriction.

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Darren G. Burke, Darren G. Candow, Philip D. Chilibeck, Lauren G. MacNeil, Brian D. Roy, Mark A. Tarnopolsky and Tim Ziegenfuss

The purpose of this study was to compare changes in muscle insulin-like growth factor-I (IGF-I) content resulting from resistance-exercise training (RET) and creatine supplementation (CR). Male (n = 24) and female (n = 18) participants with minimal resistance-exercise-training experience (≥1 year) who were participating in at least 30 min of structured physical activity (i.e., walking, jogging, cycling) 3–5 ×/wk volunteered for the study. Participants were randomly assigned in blocks (gender) to supplement with creatine (CR: 0.25 g/kg lean-tissue mass for 7 days; 0.06 g/kg lean-tissue mass for 49 days; n = 22, 12 males, 10 female) or isocaloric placebo (PL: n = 20, 12 male, 8 female) and engage in a whole-body RET program for 8 wk. Eighteen participants were classified as vegetarian (lacto-ovo or vegan; CR: 5 male, 5 female; PL: 3 male, 5 female). Muscle biopsies (vastus lateralis) were taken before and after the intervention and analyzed for IGF-I using standard immunohistochemical procedures. Stained muscle cross-sections were examined microscopically and IGF-I content quantified using image-analysis software. Results showed that RET increased intramuscular IGF-I content by 67%, with greater accumulation from CR (+78%) than PL (+54%; p = .06). There were no differences in IGF-I between vegetarians and nonvegetarians. These findings indicate that creatine supplementation during resistance-exercise training increases intramuscular IGF-I concentration in healthy men and women, independent of habitual dietary routine.

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Doeschka A. Ferro, Jan Berend Deijen, Lando L. Koppes, Willem van Mechelen, Jos W. Twisk and Madeleine L. Drent

Background:

Physical activity and fitness in adolescence may improve cognition in adulthood by increasing insulin-like growth factor I (IGF-I).

Methods:

As part of the Amsterdam Growth and Health Longitudinal Study, following subjects from age 13 to 42 years, physical activity and fitness of 303 subjects were assessed annually between the ages 13 to 16. At mean age 36, physical activity, fitness and IGF-I were measured. At mean age 42, IGF-I and cognitive factors (ie, executive functioning and visual-spatial memory) were measured. The linear regression of physical activity and fitness in adolescence and IGF-I in adulthood on cognitive scores in adulthood was investigated.

Results:

A significant association was found in males between physical activity in adolescence and executive function in adulthood (Spatial Working Memory Between Errors: β = –.18, B = –.13, 95% CI = –.259 to –.010; Spatial Working Memory Strategy: β = –.20, B = –.08, 95% CI = –.147 to –.014). No association between physical activity or fitness in adolescence and cognitive function in adulthood was found in females, nor any intermediate role for IGF-I in either sex.

Conclusions:

The results suggest a stimulating effect of adolescent physical activity in males on executive functions in adulthood, emphasizing the importance of an active lifestyle among adolescent males.

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M.R. Orenstein and C.M. Friedenreich

Purpose:

To review systematically all publications of the effects of exercise on endogenous insulin-like growth factor (IGF) to clarify the nature of this association.

Methods:

We reviewed 115 research studies in humans by subgroup of population (age; sex; athletic training status), physical activity exposure (resistance vs. aerobic activity; duration of activity) and study design.

Results:

Fifty percent of studies reviewed found no difference in total circulating IGF-1 as a result of exercise; 37% showed an increase, and 13% observed decreases in IGF-1 levels with exercise. Age influenced the effects of exercise on IGF levels. Exercise appeared to decrease IGF-1 levels in children, but to increase levels in young adults. Similar results were found for IGFBP-3.

Conclusions:

It is not yet possible to determine if exercise affects IGF levels. Important methodologic differences among studies, as well as concerns about study quality, limit the ability to draw firm conclusions.

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Michelle S. Rockwell, Madlyn I. Frisard, Janet W. Rankin, Jennifer S. Zabinsky, Ryan P. Mcmillan, Wen You, Kevin P. Davy and Matthew W. Hulver

beginning the study. Figure 1 —Experimental design. VITD = 5,000 IU of vitamin D 3 ; PTH = parathyroid hormone; fT = free testosterone; tT = total testosterone; SHBG = sex hormone-binding globulin; IGF-1 = insulin-like growth factor 1; DXA = dual-energy X-ray absorptiometry. Participants Male and female

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Kieran J. Marston, Belinda M. Brown, Stephanie R. Rainey-Smith, Sabine Bird, Linda K. Wijaya, Shaun Y. M. Teo, Ralph N. Martins and Jeremiah J. Peiffer

-related cognitive decline ( Barnes, 2015 ), with key growth factors a likely mechanism, including brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF), which are associated with neurogenesis, neuroprotection, and vascular growth, respectively

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Michael P. Corcoran, Miriam E. Nelson, Jennifer M. Sacheck, Kieran F. Reid, Dylan Kirn, Roger A. Fielding, Kenneth K.H. Chui and Sara C. Folta

, Teixeira, & Lazaretti-Castro, 2009 ; Tieland, Dirks, et al., 2012 ; Tieland, van de Rest, et al., 2012 ). Stimulation of anabolic factors such as insulin-like growth factor-1 (IGF-1) has been noted with postexercise protein and vitamin D supplementation, and therefore may aid in mitigating any age

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Kirsty J. Elliott-Sale, Adam S. Tenforde, Allyson L. Parziale, Bryan Holtzman and Kathryn E. Ackerman

rate; GH = growth hormone; PYY = peptide YY; HPA = hypothalamic–pituitary–adrenal; IGF-1 = insulin-like growth factor 1; HPG = hypothalamic–pituitary–gonadal; TSH = thyroid-stimulating hormone; T3 = triiodothyronine; T4 = thyroxine; LH = luteinizing hormone; FSH = follicle-stimulating hormone. Concept

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Jennifer Sygo, Alexandra M. Coates, Erik Sesbreno, Margo L. Mountjoy and Jamie F. Burr

) and triiodothyronine, and is associated with menstrual dysfunction and secondary functional hypothalamic amenorrhea in women ( Loucks & Thuma, 2003 ; Nattiv et al., 2007 ). LEA suppresses other hormones and substrates, including insulin, insulin-like growth factor-1 (IGF-1), glucose, growth hormone

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Ida A. Heikura, Marc Quod, Nicki Strobel, Roger Palfreeman, Rita Civil and Louise M. Burke

to a university laboratory in Ghent, Belgium for analysis of hemoglobin (Hb), hematocrit (Hct), ferritin (baseline only), thyroid-stimulating hormone (TSH), free thyroxine (T4), free triiodothyronine (T3), cortisol, total testosterone, insulin-like growth factor 1 (IGF-1), luteinizing hormone (LH