141 research outputs found
Effects of Dairy Consumption on Body Composition and Bone Properties in Youth: A Systematic Review
Background: According to previous reviews, there is no clear evidence on the effects of dairy
consumption on body composition and bone properties in pediatric populations. There is a need
for further assessment of existing findings and the methodologic quality of studies before
summarizing the evidence.
Objective: The aim of the study was to assess the quality, methodologies, and substantive
findings of randomized controlled trials (RCTs) that examined the effects of dairy consumption
on body size, body composition, and bone properties in children and adolescents.
Methods: After searching PubMed and Google Scholar up to December 2016, 15 RCTs were
retained and included in this systematic review for further analysis. The quality of the included
studies was assessed via the Jadad scale; detailed methodologic and statistical characteristics
were evaluated, and the main findings were summarized.
Results: The effects of dairy consumption were found to be significant for bone structure and
nonsignificant for body size and composition. Eight of the 11 RCTs that assessed bone found
significant effects (P , 0.05) for bone mineral content and bone mineral density (BMD), with an
average 8% increase in BMD after 16 mo of dairy consumption. Conversely, significant effects
(P , 0.05) were found only in 2 of the 14 RCTs that focused on body size (i.e., height and weight)
and in only 1 of the 11 RCTs that focused on body composition (i.e., lean mass).
Conclusions: The systematic consumption of dairy products may benefit bone structure and
development, but it does not appear to affect body composition or body size in children and
adolescents. On the basis of the Jadad scale, the methodologic quality of the 15 RCTs was rated
as good overall. However, there were methodologic disparities and limitations that may have led
to nonsignificant results, particularly for body size and composition. Future RCTs designed to
address these limitations are warranted.Brock University Library Open Access Publishing Fun
Canadian Society for Exercise Physiology Position Paper: Resistance Training in Children and Adolescents
Many position stands and review papers have refuted the myths associated with
resistance training (RT) in children and adolescents. With proper training methods, RT
for children and adolescents can be relatively safe and improve overall health. The
objective of this position paper and review is to highlight research and provide
recommendations in aspects of RT that have not been extensively reported in the
pediatric literature. In addition to the well-documented increases in muscular strength and
endurance, RT has been used to improve function in pediatric patients with cystic
fibrosis, cerebral palsy and burn victims. Increases in children’s muscular strength have
been attributed primarily to neurological adaptations due to the disproportionately higher
increase in muscle strength than in muscle size. Although most studies using
anthropometric measures have not shown significant muscle hypertrophy in children,
more sensitive measures such as magnetic resonance imaging and ultrasound have
suggested hypertrophy may occur. There is no minimum age for RT for children.
However the training and instruction must be appropriate for children and adolescents
involving a proper warm-up, cool-down and an appropriate choice of exercises. It is
recommended that low-to-moderate intensity resistance should be utilized 2-3 times per
week on non-consecutive days, with 1-2 sets initially, progressing to 4 sets of 8-15
repetitions for 8-12 exercises. These exercises can include more advanced movements
such as Olympic style lifting, plyometrics and balance training, which can enhance
strength, power, co-ordination and balance. However specific guidelines for these more
advanced techniques need to be established for youth. In conclusion, a RT program that is
within a child’s or adolescent’s capacity, involves gradual progression under qualified instruction and supervision with appropriately sized equipment can involve more
advanced or intense RT exercises which can lead to functional (i.e. muscular strength,
endurance, power, balance and co-ordination) and health benefits
Does bracing affect bone health in women with adolescent idiopathic scoliosis?
Purpose: Adolescent idiopathic scoliosis (AIS) is often associated with low bone mineral content and density (BMC,
BMD). Bracing, used to manage spine curvature, may interfere with the growth-related BMC accrual, resulting in
reduced bone strength into adulthood. The purpose of this study was to assess the effects of brace treatment on
BMC in adult women, diagnosed with AIS and braced in early adolescence.
Methods: Participants included women with AIS who: (i) underwent brace treatment (AIS-B, n = 15, 25.6 ± 5.8 yrs),
(ii) underwent no treatment (AIS, n = 15, 24.0 ± 4.0 yrs), and (iii) a healthy comparison group (CON, n = 19, 23.5 ±
3.8 yrs). BMC and body composition were assessed using dual-energy X-ray absorptiometry. Differences between
groups were examined using a oneway ANOVA or ANCOVA, as appropriate.
Results: AIS-B underwent brace treatment 27.9 ± 21.6 months, for 18.0 ± 5.4 h/d. Femoral neck BMC was lower
(p = 0.06) in AIS-B (4.54 ± 0.10 g) compared with AIS (4.89 ± 0.61 g) and CON (5.07 ± 0.58 g). Controlling for lean
body mass, calcium and vitamin D daily intake, and strenuous physical activity, femoral neck BMC was statistically
different (p = 0.02) between groups. A similar pattern was observed at other lower extremity sites (p < 0.05), but not
in the spine or upper extremities. BMC and BMD did not correlate with duration of brace treatment, duration of
daily brace wear, or overall physical activity.
Conclusion: Young women with AIS, especially those who were treated with a brace, have significantly lower BMC
in their lower limbs compared to women without AIS. However, the lack of a relationship between brace treatment
duration during adolescence and BMC during young adulthood, suggests that the brace treatment is not the likely
mechanism of the low BMC
Soft tissues, areal bone mineral density and hip geometry estimates in active young boys: The PRO-BONE study
This is the final version of the article. Available from Springer Verlag via the DOI in this record.Purpose: Soft tissues, such as fat mass (FM) and lean mass (LM), play an important role in bone development but this is poorly understood in highly active youths. The objective of this study was to determine whether FM or LM is a stronger predictor of areal bone mineral density (aBMD) and hip geometry estimates in a group of physically active boys after adjusting for height, chronological age, moderate-to-vigorous physical activity (MVPA), FM, and LM. Methods: Participants included 121 boys (13.1±1.0 years) from the PRO-BONE study. Bone mineral content (BMC) and aBMD measured at total body, femoral neck and lumbar spine using dual-energy X-ray absorptiometry (DXA), and hip structural analysis was used to estimate bone geometry at the femoral neck. Body composition was assessed using DXA. The relationships of FM and LM with bone outcomes were analysed using simple and multiple linear regression analyses. Results: Pearson correlation coefficients showed that total body (less head) aBMD was significantly correlated with LM but not FM. Multiple linear regression analyses showed that FM, after accounting for height, age, MVPA and LM had no significant relationship
with aBMD or hip geometry estimates, except for arms aBMD. By contrast, there were positive associations between LM and most aBMD and hip geometry estimates, after accounting height, age, MVPA and FM. Conclusions: The results of this study suggest that LM, and not FM, is the stronger predictor of aBMD and hip geometry estimates in physically active boys.The research leading to these results has received funding from the European Union Seventh Framework Programme ([FP7/2007–2013] under grant agreement no. PCIG13-GA-2013-618496
Role of the Myokine Irisin on Bone Homeostasis: Review of the Current Evidence
Bone is a highly dynamic tissue that is constantly adapting to micro-changes to facilitate movement. When the balance between bone building and resorption shifts more towards bone resorption, the result is reduced bone density and mineralization, as seen in osteoporosis or osteopenia. Current treatment strategies aimed to improve bone homeostasis and turnover are lacking in efficacy,
resulting in the search for new preventative and nutraceutical treatment options. The myokine irisin, since its discovery in 2012, has been shown to play an important role in many tissues including muscle, adipose, and bone. Evidence indicate that irisin is associated with increased bone formation and decreased bone resorption, leading to reduced risk of osteoporosis in post-menopausal women. In addition, low serum irisin levels have been found in individuals with osteoporosis and osteopenia. Irisin targets key signaling proteins, promoting osteoblastogenesis and reducing osteoclastogenesis. The present review summarizes the existing evidence regarding the effects of irisin on bone homeostasis.Brock Library Open Access Publishing Fun
Effects of post exercise protein supplementation on markers of bone turnover in adolescent swimmers
This is the final version. Available from the publisher via the DOI in this record.The data that support the findings of this study are available on request
from the corresponding author [PK]. The data are not publicly available due
to REB restrictions.BACKGROUND: This study examined the effects of whey protein supplementation, compared with an isocaloric carbohydrate beverage and water, consumed immediately following an intense swimming trial on bone turnover in adolescent swimmers. METHODS: Fifty-eight (31 female, 27 male) swimmers (14.1 ± 0.4 years) were stratified into three groups matched for age, sex and body mass. The protein and carbohydrate groups consumed two isocaloric post-exercise beverages each containing 0.3 g.kg- 1 of whey protein (with ~ 6 mg of calcium) or maltodextrin while the control group consumed water. Participants provided a morning, fasted, resting blood sample, then performed an intense swimming trial consisting of a maximal 200 m swim followed by a high intensity interval swimming protocol (5x100m, 5x50m and 5x25m; 1:1 work-to-rest ratio). Following swimming, they consumed their first respective post-exercise beverage, and 2 h later, they performed a second maximal swim immediately followed by the second beverage. Approximately 3 h after the second beverage, two post-consumption blood samples were collected at 8 h and 24 h from baseline. Procollagen type 1 intact N-terminal propeptide (PINP) and carboxy-terminal collagen crosslinks (CTXI) were measured in serum. The multiples of medians of PINP and CTXI were also used to calculate bone turnover rate and balance. RESULTS: No significant changes were observed in PINP. CTXI increased (+ 11%) at 8 h in all groups, but then significantly decreased (- 22%) at 24 h in the protein group only. The protein group also had a significantly higher calculated rate of bone turnover at 8 h and 24 h compared to baseline, which was not observed in the other groups. CONCLUSIONS: These results shed light on the potential importance of protein consumed shortly after intense swimming in promoting positive bone turnover responses up to 24 h following exercise in adolescent athletes. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov PRS; NCT04114045. Registered 1 October 2019 - Retrospectively registered
Comparison of different wheelchair seating on thermoregulation and perceptual responses in thermoneutral and hot conditions in children
We examined the effects of 4 different wheelchair seatings on physiological and perceptual measures in 21 healthy, pre-pubertal children (9 ± 2 years). Participants were able-bodied and did not regularly use a wheelchair. Participants sat for 2 h in Neutral (∼22.5 °C, ∼40%RH) and Hot (∼35 °C, ∼37%RH) conditions. Four seating technologies were: standard incontinent cover and cushion (SEAT1); standard incontinent cover with new cushion (SEAT2) were tested in Neutral and Hot; new non-incontinent cover with new cushion (SEAT3); new incontinent cover and new cushion (SEAT4) were tested in Neutral only. Measurements included skin blood flow (SkBF), sweating rate (SR) and leg skin temperature (TlegB) on the bottom of the leg (i.e. skin-seat interface), heart rate (HR), mean skin temperature, tympanic temperature, thermal comfort, and thermal sensation. During Neutral, SkBF and TlegB were lower (∼50% and ∼1 °C, respectively) and SR higher (∼0.5 mg cm−2·min−1) (p  0.05). During Hot, HR and temperatures were higher than in Neutral but there were no differences (p > 0.05) between SEATs. New cover and cushion improved thermoregulatory responses during Neutral but not Hot. An impermeable incontinent cover negated improvements from cushion design. Seat cover appears more important than seat cushion during typical room conditions
The impact of obesity on skeletal muscle architecture in untrained young vs. old women.
It is unknown whether loading of the lower limbs through additional storage of fat mass as evident in obesity would promote muscular adaptations similar to those seen with resistance exercise. It is also unclear whether ageing modulates any such adjustments. This study aimed to examine the relationships between adiposity, ageing and skeletal muscle size and architecture. A total of 100 untrained healthy women were categorised by age into young (Y) (mean ± SD: 26.7 ± 9.4 years) vs. old (O) (65.1 ± 7.2 years) and body mass index (BMI) classification (underweight, normal weight, overweight and obese). Participants were assessed for body fat using dual energy x-ray absorptiometry, and for gastrocnemius medialis (GM) muscle architecture (skeletal muscle fascicle pennation angle and length) and size [GM muscle volume and physiological cross-sectional area (PCSA)] using B-mode ultrasonography. GM fascicle pennation angle (FPA) in the obese Y females was 25% greater than underweight (P = 0.001) and 25% greater than normal weight (P = 0.001) individuals, while O females had 32 and 22% greater FPA than their underweight (P = 0.008) and normal weight (P = 0.003) counterparts. Furthermore, FPA correlated with body mass in both Y and O females (Y r = 0.303; P 0.05). Both GM muscle volume (P = 0.003) and PCSA (P = 0.004) exhibited significant age × BMI interactions. In addition, muscle volume and PCSA correlated with BMI, body mass and fat mass. Interestingly, ageing reduced both the degree of association in these correlations (P < 0.05) and the slope of the regressions (P < 0.05). Our findings partly support our hypotheses in that obesity-associated changes in GM PCSA and volume differed between the young and old. The younger GM muscle adapted to the loading induced by high levels of body mass, adiposity and BMI by increasing its volume and increasing its pennation angle, ultimately enabling it to produce higher maximum torque. Such an adaptation to increased loading did not occur in the older GM muscle. Nonetheless, the older GM muscle FPA increased to a similar extent to that seen in young GM muscle, an effect which partly explains the relatively enhanced absolute maximum torque observed in obese older females
Characterization of sclerostin’s response within white adipose tissue to an obesogenic diet at rest and in response to acute exercise in male mice
This study examined the effect of a high-fat diet (HFD) on sclerostin content within subcutaneous inguinal visceral white adipose tissue (iWAT), and visceral epididymal WAT (eWAT) depots at rest and in response to acute aerobic exercise. Male C57BL/6 mice (n=40, 18 weeks of age) underwent 10 weeks of either a low-fat diet (LFD) or HFD. Within each diet group, mice were assigned to either remain sedentary (SED) or perform 2h of endurance treadmill exercise at 15 m·min-1 with 5° incline (EX), creating 4 groups: LFD+SED (N=10), LFD+EX (N=10), HFD+SED (N=10), and HFD+EX (N=10). Serum and WAT depots were collected 2h post-exercise. Serum sclerostin showed a diet-by-exercise interaction, reflecting HFD+EX mice having higher concentration than HFD-SED (+31%, p=0.03), and LFD mice being unresponsive to exercise. iWAT sclerostin content decreased post-exercise in both 28 kDa (-31%, p=0.04) and 30 kDa bands (-36%, main effect for exercise, p=0.02). iWAT b-catenin (+44%, p=0.03) and GSK3b content were elevated in HFD mice compared to LFD (+128%, main effect for diet, p=0.005). Monomeric sclerostin content was abolished in eWAT of HFD mice (-96%, main effect for diet, p<0.0001), was only detectable as a 30 kDa band in LFD mice and was unresponsive to exercise. b-catenin and GSK3b were both unresponsive to diet and exercise within eWAT. These results characterized sclerostin’s mobilization to WAT depots in response to acute exercise, which appears to be specific to a reduction in iWAT and identified a differential regulation of sclerostin’s form/post-translational modifications depending on diet and WAT depot.This research was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC grant to P. Klentrou # 2020-00014). N. Kurgan, B. Baranowski and Joshua Stoikos hold NSERC doctoral scholarships
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