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1.
Nutr Res ; 119: 65-75, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37757641

ABSTRACT

Increases in postprandial lipids are linked to the development of cardiometabolic and fatty liver disease. Prior work has suggested that dairy possesses beneficial cardiometabolic effects and thus the aim of the current investigation was to test the hypotheses that the habitual consumption of dairy, in the form of skim milk powder (SMP), would protect against increases in circulating lipids and liver lipid accumulation following an oral fat challenge in rats. Male rats were fed either a semipurified low-fat control diet with casein or a diet with an equivalent amount of protein (∼13% kcal) provided through skim milk powder (SMP) for 6 weeks (n = 40/group). Rats were then given an oral gavage of palm oil (5 mL/kg body weight) or an equivalent volume of water, and serum and liver were harvested 90 minutes or 4 hours after. Rats fed the SMP diet gained less weight than controls but there were no differences in glucose tolerance between groups. The fat gavage increased serum lipids in both diet groups, whereas there was a main effect of the fat challenge to increase, and the SMP diet, to decrease liver triacylglycerol accumulation. The percentage of saturated and monounsaturated fatty acids and the protein content/activity of lipogenic enzymes were reduced in livers from SMP-fed rats, whereas the percentage of polyunsaturated fatty acids was increased. In summary, we provide evidence that SMP consumption, although not protecting against postprandial lipemia, markedly attenuates triacylglycerol accumulation and the relative amount of saturated and monounsaturated fatty acids in the liver.


Subject(s)
Cardiovascular Diseases , Hyperlipidemias , Rats , Male , Animals , Triglycerides , Milk , Lipids , Powders , Diet , Liver/metabolism , Hyperlipidemias/etiology , Fatty Acids, Monounsaturated , Cardiovascular Diseases/metabolism , Fatty Acids/metabolism , Dietary Fats/metabolism
2.
Pediatr Exerc Sci ; 35(1): 41-47, 2023 02 01.
Article in English | MEDLINE | ID: mdl-35894972

ABSTRACT

This study examined differences in resting concentrations of markers of bone formation and resorption, and osteokines between female adolescent (12-16 y) swimmers, soccer players, and nonathletic controls. Resting, morning blood samples were obtained after an overnight fast from 20 swimmers, 20 soccer players, and 20 nonathletic controls, matched for age. carboxyl-terminal cross-linking telopeptide of type I collagen (CTX), amino-terminal propeptide of type I collagen (P1NP), total osteocalcin (OC), sclerostin, osteoprotegerin (OPG), and receptor activator of nuclear factor kappa B ligand (RANKL) were analyzed in serum. After controlling for percent body fat, there were no significant differences between swimmers and nonathletic controls in any of the measured markers. In contrast, soccer players had significantly higher P1NP (89.5 [25.6] ng·mL-1), OC (57.6 [22.9] ng·mL-1), and OPG (1052.5 [612.6] pg·mL-1) compared with both swimmers (P1NP: 66.5 [20.9] ng·mL-1; OC: 24.9 [12.5] ng·mL-1; OPG: 275.2 [83.8] pg·mL-1) and controls (P1NP: 58.5 [16.2] ng·mL-1; OC: 23.2 [11.9] ng·mL-1; OPG: 265.4 [97.6] pg·mL-1), with no differences in CTX, sclerostin, and RANKL. These results suggest that bone formation is higher in adolescent females engaged in high-impact sports like soccer compared with swimmers and controls.


Subject(s)
Collagen Type I , Sports , Humans , Female , Adolescent , Biomarkers , Athletes , Bone Remodeling , Osteocalcin
3.
Article in English | MEDLINE | ID: mdl-36498451

ABSTRACT

The authors of "Effects of Post-Exercise Whey Protein Consumption on Recovery Indices in Adolescent Swimmers" report an error in Table 1 of their article [...].

4.
Children (Basel) ; 9(11)2022 Nov 06.
Article in English | MEDLINE | ID: mdl-36360431

ABSTRACT

Our study examined how increased dairy consumption versus habitually low dairy consumption, against a background of healthy eating (and exercise), influenced diet quality, nutrient intake, and snacking in Canadian female adolescents (14.8 ± 2.2 years) with overweight/obesity (OW/OB). We also explored dairy consumption patterns in the group consuming dairy products. Participants were randomized into two groups: higher/recommended dairy (RDa; 4 svg/d; n = 24) or low dairy (LDa; 0−2 svg/d; n = 23). Both groups participated in a 12-week, eucaloric, lifestyle modification intervention consisting of exercise training and nutritional counseling. The intervention increased the total Canadian Healthy Eating Index score (p < 0.001) with no differences between groups. The "other food" sub-score improved more in RDa than LDa (p = 0.02), and the "saturated fat" sub-score increased more in LDa than RDa (p = 0.02). The intervention significantly increased the consumption of dairy-related nutrients more in RDa than LDa (p < 0.05). The intervention also decreased snack size in both groups (p = 0.01) and improved percentage of healthy snack energy intake more in RDa than LDa (p = 0.04). More servings of dairy products were consumed as snacks than at breakfast, lunch, or dinner (p < 0.05). Thus, our study improved diet quality, and dairy product consumption improved intakes of key related nutrients and snack consumption in adolescents with OW/OB.

5.
Nutrients ; 14(21)2022 Oct 28.
Article in English | MEDLINE | ID: mdl-36364794

ABSTRACT

High-intensity/impact exercise elicits a transient increase in inflammatory biomarkers. Consuming nutrient-dense wholefoods, like milk, following exercise may modulate post-exercise inflammation and aid recovery. We examined the effect of post-exercise skim milk consumption (versus an isoenergetic, isovolumetric carbohydrate [CHO] drink) on acute exercise-induced inflammation in untrained females. Using a randomized crossover design, 13 healthy females (age = 20 ± 2.3 y; BMI = 21.0 ± 1.1 kg/m2) completed two bouts of combined resistance/plyometric exercise followed by either skim milk (MILK) or CHO at 5-min and 1 h post-exercise. Serum interleukin [IL]-1ß, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α) concentrations were measured at pre-exercise, 15-min, 75-min, 24 h, and 48 h post-exercise. IL-6 increased 15-min post-exercise vs. all other timepoints (time effect, p = 0.017). Between 24 and 48 h, IL-10 decreased and increased in the MILK and CHO conditions, respectively (interaction, p = 0.018). There were no significant effects for IL-1ß or TNF-α. Relative concentrations of IL-1ß (p = 0.049) and IL-10 (p = 0.028) at 48 h post-exercise were lower in MILK vs. CHO. Milk post-exercise did not influence the absolute concentration of pro-inflammatory cytokines; however, there were divergent responses for the anti-inflammatory cytokine, IL-10, and milk reduced the relative inflammatory response at 48 h (vs. CHO) for IL-1ß and IL-10. This demonstrates the potential for milk to modulate inflammation post-exercise in this sample.


Subject(s)
Interleukin-10 , Plyometric Exercise , Adolescent , Adult , Female , Humans , Young Adult , Cytokines , Inflammation , Interleukin-6 , Tumor Necrosis Factor-alpha , Cross-Over Studies
6.
Front Nutr ; 9: 840973, 2022.
Article in English | MEDLINE | ID: mdl-35571916

ABSTRACT

Dairy products and impact exercise have previously been identified to be independently beneficial for bone mineral properties, however, it is unknown how the combination of these two osteogenic interventions may alter acute bone turnover. Using a randomized crossover design, we compared the acute effects of consuming milk vs. an isoenergetic carbohydrate control beverage on bone biomarkers following loading exercise. Thirteen healthy female participants (Age = 20.3 ± 2.3y; BMI = 21.0 ± 1.1 kg/m2) consumed either 550 mL of 0% skim white milk (MILK) or 52.7 g of maltodextrin in 550 mL of water (CHO), both 5 min and 1 h following completion of a combined plyometric (198 impacts) and resistance exercise (3-4 sets/exercise, 8-12 reps/set, ∼75% 1-RM) bout. Venous blood samples were obtained pre-exercise, and 15 min, 75 min, 24 h and 48 h post-exercise to assess serum concentrations of bone resorption biomarkers, specifically carboxyl-terminal crosslinking telopeptide of type I collagen (CTX), receptor activator nuclear factor kappa-ß ligand (RANKL), and sclerostin (SOST), as well as bone formation biomarkers, specifically osteoprotegerin (OPG) and osteocalcin (OC). When absolute biomarker concentrations were examined, there were no interaction or group effects for any biomarker, however, there were main time effects (p < 0.05) for RANKL, SOST, and OC, which were lower, and the OPG: OPG/RANKL ratio, which was higher at 75 min post-exercise compared with baseline in both conditions. In addition to assessing absolute biomarker concentrations at specific timepoints, we also evaluated the relative (% change) cumulative post-exercise response (75 min to 48 h) using an area under the curve (AUC) analysis. This analysis showed that the relative post-exercise CTX response was significantly lower in the MILK compared to the CHO condition (p = 0.03), with no differences observed in the other biomarkers. These results show that while milk does not appear to alter absolute concentrations of bone biomarkers compared to CHO, it may attenuate relative post-exercise bone resorption (i.e., blunt the usual catabolic response to exercise).

7.
J Int Soc Sports Nutr ; 19(1): 17-33, 2022.
Article in English | MEDLINE | ID: mdl-35599913

ABSTRACT

Background: During a period of intensified exercise (e.g. training/identification camps), often undertaken by competitive youth athletes, the maintenance of muscle function and peak performance can become challenging due to an accumulation of fatigue. The provision of post-exercise dairy protein in adults has been previously shown to accelerate recovery; however, its efficacy in youth athletes is currently unknown. Therefore, the purpose of this study was to examine the effects of increased dairy protein consumption with plain Greek yogurt (GY) on performance and recovery indices during an intensified soccer training camp in adolescent female soccer players. Methods: Thirteen players (14.3 ± 1.3 years) participated in a randomized, double blinded, crossover design study where they received 3 servings/day of either GY (~115 kcal, 17 g protein, ~11.5 g carbohydrates) or an isoenergetic carbohydrate control (CHO, ~115 kcal, 0.04 g protein, ~28.6 g carbohydrates) during two 5-day soccer-specific training camps. Performance was assessed before and after each training camp. Fasted, morning, creatine kinase (CK), insulin-like growth factor-1 (IGF-1), C-reactive protein (CRP), interleukin 6 (IL6), interleukin 10 (IL10) and tumor necrosis factor-α (TNFα) were measured in plasma pre- and post-training. Results: Training led to decrements in counter-movement jump (p = 0.01), broad jump (p = 0.04) and aerobic capacity (p = 0.006), with no effect of GY. A significant increase in anti-inflammatory cytokine IL10 was observed from pre- to post-training in GY (+26% [p = 0.008]) but not in CHO (p = 0.89). CRP and CK increased (+65% [p = 0.005] and +119% [p ≤ 0.001], respectively), while IGF-1 decreased (-34% [p ≤ 0.001]) from pre- to post-training with no difference between conditions. Conclusions: These results demonstrate that consumption of GY did not offer any added recovery benefit with respect to measures of performance and in the attenuation of exercise-induced muscle damage above that achieved with energy-matched carbohydrate in this group of young female soccer players. However, regular consumption of GY may assist with the acute anti-inflammatory response during periods of intensified training in adolescent athletes.


Subject(s)
Athletic Performance , Soccer , Yogurt , Adolescent , Athletes , Athletic Performance/physiology , C-Reactive Protein/analysis , Carbohydrates , Creatine Kinase , Cross-Over Studies , Female , Humans , Inflammation , Insulin-Like Growth Factor I , Interleukin-10 , Soccer/physiology
8.
Front Physiol ; 13: 1049604, 2022.
Article in English | MEDLINE | ID: mdl-36685198

ABSTRACT

Introduction: Exercise and consumption of dairy foods have been shown to improve bone mineralization. However, little is known about the magnitude and timing of their synergistic effects on markers and regulators of bone metabolism in response to acute exercise in adolescent females with obesity, a population susceptible to altered bone metabolism and mineral properties. This study examined the influence of twelve weeks of exercise training and nutritional counselling on the bone biochemical marker response to acute exercise and whether higher dairy consumption could further influence the response. Methods: Thirty adolescent females (14.3 ± 2.0 years) with overweight/obesity (OW/OB) completed a 12-week lifestyle modification intervention involving exercise training and nutritional counselling. Participants were randomized into two groups: higher dairy intake (RDa; 4 servings/day; n = 14) or low dairy intake (LDa; 0-2 servings/d; n = 16). Participants performed one bout of plyometric exercise (5 circuits; 120 jumps) both pre- and post-intervention. Blood samples were taken at rest, 5 min and 1 h post-exercise. Serum sclerostin, osteocalcin (OC), osteoprotegerin (OPG), receptor activator nuclear factor kappa B ligand (RANKL), and C-terminal telopeptide of type 1 collagen (ßCTX) concentrations were measured. Results: While there was an overall increase in sclerostin pre-intervention from pre to 5 min post-exercise (+11% p = 0.04), this response was significantly decreased post-intervention (-25%, p = 0.03) independent of dairy intake. The OPG:RANKL ratio was unresponsive to acute exercise pre-intervention but increased 1 h post-exercise (+2.6 AU; p < 0.001) post-intervention. Dairy intake did not further influence these absolute responses. However, after the 12-week intervention, the RDa group showed a decrease in the relative RANKL post-exercise response (-21.9%; p < 0.01), leading to a consistent increase in the relative OPG:RANKL ratio response, which was not the case in the LDa group. There was no influence of the intervention or dairy product intake on OC, OPG, or ßCTX responses to acute exercise (p > 0.05). Conclusion: A lifestyle modification intervention involving exercise training blunts the increase in sclerostin and can augment the increase in OPG:RANKL ratio to acute exercise in adolescent females with OW/OB, while dairy product consumption did not further influence these responses.

9.
Br J Nutr ; 127(1): 68-77, 2022 01 14.
Article in English | MEDLINE | ID: mdl-34027846

ABSTRACT

Dairy fat is rich in SFA such as palmitic acid (16:0) but low in linoleic acid (18:2n-6). The natural carbon 13 enrichment (δ13C) of 16:0 is higher in dairy fat than in most of the food supply. In adults, serum levels of pentadecanoic acid (15:0) and heptadecanoic acid (17:0) are recognised as biomarkers of dairy intake. In adolescents, no study has evaluated serum fatty acid levels or δ13C in response to chronic dairy consumption. The objectives of this study were to evaluate whether increased dairy product consumption can modulate (1) serum fatty acid levels and (2) 16:0 δ13C in adolescents with overweight/obesity who followed a 12-week weight management programme. This secondary analysis of a randomised control trial included two groups of adolescent females: recommended dairy (RDa; n 23) and low dairy (LDa; n 23). The RDa group was given 4 servings/d of dairy products while the LDa group maintained dairy intakes at ≤ 2 servings/d. Blood was sampled before and after the intervention. Lipids were extracted and separated, and fatty acids were quantified by GC. Isotope ratio MS was used to assess 16:0 δ13C. There were no group differences on serum changes of 15:0 or 17:0. Within TAG, 18:2n-6 was lowered by 7·4 % only in the RDa group (P = 0·040). The difference in delta 16:0 δ13C between the LDa and RDa groups did not reach statistical significance (P = 0·070). Reductions in serum 18:2n-6 by dairy consumption could have positive health implications, but more studies are needed to confirm this assertion.


Subject(s)
Linoleic Acid , Overweight , Adolescent , Adult , Dairy Products/analysis , Fatty Acids , Female , Humans , Obesity
10.
J Sports Sci ; 39(21): 2434-2443, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34157957

ABSTRACT

When designing efficacy trials, researchers have a responsibility to "do no harm" and to "do good". Given the psychological vulnerability of adolescent girls with overweight and obesity, it is important to consider the implications of participating in weight-related research studies. We investigated psychological outcomes from a 12-week laboratory-based randomised controlled trial aimed at improving body composition and bone health in adolescent girls with overweight and obesity. Sixty-three participants were randomised to three groups (Recommended dairy diet plus exercise (RDa, n = 24); Low dairy diet plus exercise (LDa, n = 25); no-intervention control (n = 14)). Self-Determination Theory-informed strategies were applied in both intervention groups to foster motivation and enhance psychological wellbeing. Motivation, perceived competence and self-perceptions were measured at 0 and 12 weeks. Fifty-four participants (24 RDa, 23 LDa, 7 Control) provided complete psychological data. There were no between group differences in 0- to 12-week change in motivation, perceived competence or global self-worth. Both intervention groups showed significant improvements in physical self-worth (p = 0.001), body satisfaction (p = 0.002) and perceived physical conditioning (p = 0.002), compared with the control group. A theory-informed, laboratory-based diet and exercise intervention produced favourable psychological outcomes for adolescent girls with overweight and obesity.


Subject(s)
Diet, Reducing , Exercise Therapy , Healthy Lifestyle , Overweight/psychology , Overweight/therapy , Pediatric Obesity/psychology , Pediatric Obesity/therapy , Adolescent , Behavior Therapy , Body Composition , Child , Diet, Healthy , Female , Humans , Motivation , Personal Autonomy , Self Concept , Treatment Outcome
11.
Front Nutr ; 8: 673589, 2021.
Article in English | MEDLINE | ID: mdl-34095194

ABSTRACT

Background: The presence of obesity and some cardiometabolic disease risk factors in childhood and adolescence track into adulthood. Intake of dairy products has been shown to be inversely related to adiposity and cardiometabolic variables in youth. However, limited research has examined cardiometabolic disease risk factors following increased dairy product consumption as part of a lifestyle modification intervention in youth with overweight/obesity. This secondary analysis aimed to determine whether 12 weeks of increased dairy consumption, as part of a lifestyle modification program, affects cardiometabolic variables in adolescent females (range: 10-18 years) with overweight/obesity (BMI > 85th centile). Methods: Participants were randomized into two groups: higher dairy intake (RDa; four servings/day [to reflect previous Canada's Food Guide recommendations]; n = 23) or low dairy intake (LDa; 0-2 servings/day; n = 23). Both RDa and LDa participated in a 12-week, eucaloric, lifestyle modification intervention consisting of exercise training, and nutritional counseling. Adiposity (percent body fat [%BF]), dietary intake, and measures of cardiometabolic health were measured pre- and post-intervention. Results: There were no significant changes over time within groups or differences over time between groups for triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), TC/HDL ratio, low-density lipoprotein cholesterol (LDL), glucose, insulin, homeostatic model assessment of insulin resistance, adiponectin, and tumor necrosis factor alpha (TNF-α) (main effects of time and interactions, p > 0.05). Leptin decreased over the 12-week lifestyle intervention in both groups (main effect of time, p = 0.02). After combining the groups (n = 46), significant correlations were found between change in %BF and change in some cardiometabolic variables (HDL [r = -0.40], TC/HDL ratio [r = 0.42], LDL [r = 0.36], and TNF-α [r = 0.35], p < 0.05). After controlling for change in dairy product intake, the correlations were unchanged. Conclusion: Our findings demonstrate that increased dairy product consumption, as part of a lifestyle modification, weight management intervention, had a neutral effect on cardiometabolic disease risk factors in adolescent females with overweight/obesity. Change in dairy product intake did not influence the relationships between change in adiposity and change in cardiometabolic variables. Future research designed to primarily assess the effect of increased dairy product consumption on cardiometabolic disease risk factors in this population is warranted. Clinical Trial Registration: Clinicaltrials.gov; NCT#02581813.

12.
Article in English | MEDLINE | ID: mdl-33920132

ABSTRACT

Purpose: The transition to university is often accompanied by the adoption of negative lifestyle habits, which may result in weight and fat gain. While this has been demonstrated during 1st year, little is known about subsequent years. We investigated changes in body composition, energy expenditure, and dietary/energy intake from 1st to 4th year university. Methods: Thirty-eight students (14 males, 24 females) completed a lifestyle questionnaire and had their body mass, fat mass, lean body mass (LBM), and body fat percentage (%BF) measured three times: at the beginning and end of 1st year, and end of 4th year. Results: During 1st year, body mass, fat mass, LBM, and %BF increased (+3.2 ± 3.8 kg, +2.5 ± 3.0 kg, +0.7 ± 2.1 kg, +2.3 ± 4.9%, respectively; p < 0.01), while daily energy intake and expenditure decreased (-359 ± 1019 kcal·d-1 and -434 ± 786 kcal·d-1, respectively; p < 0.01). Between the end of 1st year and end of 4th year, body mass, LBM, and energy expenditure increased (+3.2 ± 3.8 kg, +1.3 ± 2.9 kg, +209 ± 703 kcal·d-1, respectively; p ≤ 0.05), while %BF, fat mass, and energy intake did not change. Conclusions: Although %BF and fat mass remained stable from the end of 1st year to the end of 4th year in this group of university students, the positive increase in energy expenditure was not enough to reverse the weight and fat gained during 1st year.


Subject(s)
Body Composition , Universities , Energy Intake , Energy Metabolism , Female , Follow-Up Studies , Humans , Male
13.
Front Nutr ; 8: 798036, 2021.
Article in English | MEDLINE | ID: mdl-35004824

ABSTRACT

Dairy products can act as a dietary source of lithium (Li), and a recent study in university-aged males demonstrated that Greek yogurt (GY) supplementation augmented gains in fat free mass, strength and bone formation after 12 weeks of resistance exercise training compared to carbohydrate (CHO) pudding supplementation. Here, we performed secondary analyses to explore whether GY would alter serum Li levels and whether changes in serum Li would associate with changes in body composition, strength, and bone turnover markers. Results show that the GY group maintained serum Li levels after exercise training, whereas the CHO group did not. Maintaining/elevating serum Li levels was also associated with greater gains in strength and reductions in bone resorption. However, controlling for other dietary factors in GY such as protein and calcium weakened these associations. Thus, future studies should assess the causative role, if any, of dietary Li alone on strength and bone resorption in humans.

14.
Front Endocrinol (Lausanne) ; 11: 531926, 2020.
Article in English | MEDLINE | ID: mdl-33362710

ABSTRACT

Background: In adults, excess adiposity has been associated with low-grade, chronic inflammation and compromised bone health, but less is known about these linkages in children. The purpose of this study was to compare the circulating levels of inflammatory cytokines, adipokines, osteokines, and bone markers at rest and in response to plyometric exercise between obese and normal weight adolescent females. Methods: Ten normal weight (BMI = 21.3 ± 2) and 10 obese (BMI = 32.9 ± 4), postmenarcheal females, aged 13-17 years, performed one bout of plyometric exercise (5 circuits; 120 jumps). Blood samples were taken at rest, 5 min, 1 h, and 24 h post-exercise. Tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), insulin, leptin, osteocalcin, carboxy-terminal telopeptide (CTX), sclerostin, and parathyroid hormone (PTH) were measured in serum. Results: Cytokines were not different between groups at rest or over time with IL-6 increasing (+31%; p = 0.04) 5 min post-exercise and TNF-α decreasing (-9%; p = 0.001) 1 h post-exercise. Insulin and leptin were higher in the obese compared to the normal weight females. In both groups, insulin significantly increased 5 min post-exercise but remained elevated 1 h post-exercise only in the obese group. Leptin did not change in response to exercise. Osteocalcin was lower in the obese group across time and increased (+12%; p = 0.02) 24 h post-exercise in both groups. CTX was similar between groups at rest and decreased (-24%; p < 0.001) 1 h post-exercise. Sclerostin was similar between groups at rest, but there was a significant interaction reflecting a significant increase (+29%; p = 0.04) 5 min post-exercise in the obese group and a non-significant decrease (-13%; p = 0.08) in normal weight controls. PTH increased 5 min post-exercise, dropped 1 h post-exercise to lower than pre-exercise, and returned to baseline 24 h post-exercise in both groups. Conclusion: Obese adolescent females from our study had no evidence of resting inflammation or differences in bone resorption but show blunted bone formation when compared to normal weight controls. The direction and temporal changes in inflammatory cytokines, adipokines, and bone turnover markers to exercise were similar in both groups, reflecting an overall bone anabolic response for most biomarkers, except sclerostin, which increased only in the obese females immediately post-exercise, suggesting a different systemic regulation of sclerostin depending on adiposity.


Subject(s)
Adipokines/blood , Cytokines/blood , Exercise/physiology , Osteocalcin/blood , Parathyroid Hormone/blood , Pediatric Obesity/blood , Adolescent , Biomarkers/blood , Bone Remodeling/physiology , Female , Humans
15.
Article in English | MEDLINE | ID: mdl-33114186

ABSTRACT

Purpose: This study examined the effect of whey protein consumption following high-intensity interval swimming (HIIS) on muscle damage, inflammatory cytokines and performance in adolescent swimmers. Methods: Fifty-four swimmers (11-17 years-old) were stratified by age, sex and body mass to a whey protein (PRO), isoenergetic carbohydrate (CHO) or a water/placebo (H2O) group. Following baseline blood samples (06:00 h) and a standardised breakfast, participants performed a maximal 200 m swim, followed by HIIS. A total of two post-exercise boluses were consumed following HIIS and ~5 h post-baseline. Blood and 200 m performance measurements were repeated at 5 h, 8 h and 24 h from baseline. Muscle soreness was assessed at 24 h. Creatine kinase (CK), interleukin-6 (IL-6), interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-α) were measured in plasma. Results: No difference in 200 m swim performance was observed between groups. CK activity was elevated at 5 h compared to baseline and 24 h and at 8 h compared to all other timepoints, with no differences between groups. Muscle soreness was lower in PRO compared to H2O (p = 0.04). Anti-inflammatory IL-10 increased at 8 h in PRO, while it decreased in CHO and H2O. Conclusions: Post-exercise consumption of whey protein appears to have no additional benefit on recovery indices following HIIS compared to isoenergetic amounts of carbohydrate in adolescent swimmers. However, it may assist with the acute-inflammatory response.


Subject(s)
Dietary Supplements , Myalgia/prevention & control , Sports Nutritional Physiological Phenomena , Swimming , Whey Proteins/administration & dosage , Adolescent , Athletes , Child , Creatine Kinase/blood , Cytokines/blood , Dietary Carbohydrates/administration & dosage , Female , Humans , Male , Muscle, Skeletal
16.
Pediatr Obes ; 15(12): e12690, 2020 12.
Article in English | MEDLINE | ID: mdl-32602233

ABSTRACT

BACKGROUND: Exercise can improve body composition in adolescents and adults with overweight/obesity. Consumption of dairy foods, as part of a healthy lifestyle program, can also promote favourable body composition changes in adults with overweight/obesity. However, the few studies examining these combined effects on body composition in adolescents are inconclusive. OBJECTIVE: To determine whether increased dairy product consumption, as part of a lifestyle modification program featuring exercise training and dietary guidance promotes favourable body composition changes in adolescent females with overweight/obesity. METHODS: Fifty-four participants (age: 14.8 ± 2.2y; BMI percentile: 95th ± 6) assigned to three groups completed the study. There were two experimental groups: recommended dairy (RDa; n = 24) and low dairy (LDa; n = 22), and a no-intervention control group (Con; n = 8). RDa and LDa participated in a 12-week, eucaloric, lifestyle modification intervention consisting of mixed-mode exercise (3x/week), and nutritional counselling. RDa was provided 4 servings/day of dairy foods, while LDa and Con maintained habitually low intakes (0-2 servings/day). Body weight/composition, waist/hip circumference, cardiovascular fitness and food intake were assessed at weeks 0 and 12. RESULTS: Weight did not significantly change in any group. RDa significantly decreased fat mass (FM) and increased lean mass (LM) more than LDa and Con (FM: -1.3 ± 2.1 kg, -1.1 ± 2.0 kg, 0.8 ± 1.8 kg; LM: 1.5 ± 1.9 kg, 0.7 ± 1.6 kg, 0.5 ± 1.4 kg, respectively). LDa also significantly decreased FM and increased LM more than Con (P < .005; all interactions). CONCLUSION: The inclusion of dairy foods in the diet of adolescent females with overweight/obesity, as part of a diet and exercise intervention, favourably improves body composition in the absence of weight loss.


Subject(s)
Body Composition , Dairy Products , Exercise , Overweight/therapy , Pediatric Obesity/therapy , Weight Reduction Programs , Adolescent , Diet , Female , Humans
17.
J Int Soc Sports Nutr ; 17(1): 20, 2020 Apr 15.
Article in English | MEDLINE | ID: mdl-32293471

ABSTRACT

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.


Subject(s)
Bone Remodeling , Dietary Supplements , Swimming , Whey Proteins/administration & dosage , Adolescent , Beverages , Double-Blind Method , Female , Humans , Male , Polysaccharides/administration & dosage , Sports Nutritional Physiological Phenomena , Water/administration & dosage
18.
Pediatr Res ; 88(6): 910-916, 2020 12.
Article in English | MEDLINE | ID: mdl-32179870

ABSTRACT

BACKGROUND: We examined whether increased dairy intake was associated with changes in the levels of bone-related biochemical markers in overweight/obese adolescent girls undergoing a 12-week diet and exercise intervention. METHODS: Thirty-five girls were assigned to a low dairy group (LDa; 0-2 servings/day; n = 16) or a higher dairy group (RDa; 4 servings/day; n = 19). Morning, fasted/resting blood samples were collected before and after the intervention and serum concentrations of procollagen-type-1-N-terminal-propeptide (P1NP), ß-isomerized-C-terminal-cross-linking-telopeptides (ß-CTX), osteocalcin (OC), 25-hydroxyvitamin-D, sclerostin and parathyroid hormone were measured. RESULTS: At baseline, there were no significant differences between groups in any bone variable. Changes (∆) over time in ß-CTΧ (p = 0.035; interaction) and OC (p = 0.015; interaction) were significantly different between groups characterized by decreases in RDa and increases in LDa. P1NP and P1NP:ß-CTX ratio decreased in both groups (main time effects: p = 0.003, p = 0.041, respectively). ∆ß-CTX (r = -0.37; p = 0.028) and ∆OC (r = -0.39; p = 0.021) were correlated with average number of dairy servings consumed during the study and with each other (r = 0.45; p = 0.006). ∆OC was not correlated with ∆P1NP (r = 0.19; p = 0.27). CONCLUSIONS: Our results suggest that the osteogenic response to a diet and exercise program in this population can be improved with increased dairy intake via a decrease in bone resorption. IMPACT: We demonstrated that bone resorption significantly decreased over the intervention period in the group consuming adequate levels of dairy products compared to the group consuming little to no dairy products. Change in bone resorption was negatively correlated with average number of dairy servings consumed during the study. Our results suggest that the osteogenic response to a diet and exercise program in this population can be improved with increased dairy intake via a decrease in bone resorption. This is the first study to date to assess changes in bone marker status following a lifestyle intervention with exercise and different intakes of dairy products in a sample of OW/OB adolescent girls. We provide evidence that increased dairy product intake is associated with beneficial changes in circulating levels of bone-related biochemical markers in these girls undergoing a 12-week lifestyle (nutrition counseling and exercise training) intervention program. The main impact of our work relates particularly to the recent changes to Canada's food guide. Using the old recommendations, we demonstrated that the inclusion of 3-4 servings of mixed dairy foods per day improved bone health (primarily as a decrease in resorption) in OW/OB adolescent girls and that this level of dairy product intake appears appropriate and should still be encouraged for this age group. We also demonstrated that adolescent girls, a group that usually does not sufficiently consume dairy products, also improved their BMI percentile and nutrient intake with the inclusion of dairy products in their diets.


Subject(s)
Bone Resorption , Dairy Products , Diet , Exercise Therapy/methods , Obesity/blood , Overweight/blood , Adaptor Proteins, Signal Transducing/blood , Adolescent , Anthropometry , Body Mass Index , Bone and Bones , Child , Collagen Type I/blood , Energy Intake , Feeding Behavior , Female , Humans , Osteocalcin/blood , Osteogenesis , Parathyroid Hormone/blood , Peptide Fragments/blood , Peptides/blood , Procollagen/blood , Vitamin D/analogs & derivatives , Vitamin D/blood
19.
Pediatr Exerc Sci ; 32(2): 65-72, 2020 05 01.
Article in English | MEDLINE | ID: mdl-31770720

ABSTRACT

This study compared salivary and serum concentrations of testosterone and cortisol at rest and in response to intense multitask exercise in boys and men. Early morning saliva and venous blood samples were obtained before and 15 minutes after exercise from 30 competitive swimmers (15 boys, age 14.3 [1.9] y; 15 men, age 21.7 [3.1] y). Exercise included a swim-bench maximal strength task and an all-out 200-m swim, followed by a high-intensity interval swimming protocol (5 × 100 m, 5 × 50 m, and 5 × 25 m). At baseline, fasting testosterone (but not cortisol) concentration was higher in men than boys in serum and saliva (P < .05). Salivary and serum cortisol increased postexercise, with a greater increase in men compared with boys (men: 226% and 242%; boys: 78% and 64%, respectively; group by time interaction, P < .05). Testosterone was reduced postexercise in serum but not in saliva (men: -14.7% and 0.1%; boys: -33.9% and -4.5%, respectively, fluid by time interaction, P < .01). Serum and salivary cortisol (but not testosterone), preexercise and postexercise values were strongly correlated in both men and boys (r = .79 and .82, respectively; P < .01). In summary, early morning high-intensity exercise results in a decrease in testosterone in serum, but not saliva, and an increase in cortisol irrespective of the fluid used, in both boys and men. When examining immediate postexercise changes, the lack of correlation in testosterone between saliva and serum suggests that saliva may not be an appropriate fluid to examine changes in testosterone. The high correlation observed between serum and saliva for cortisol indicates that, in both boys and men, saliva may be used to monitor the immediate cortisol response to exercise.


Subject(s)
Hydrocortisone/analysis , Hydrocortisone/blood , Swimming/physiology , Testosterone/analysis , Testosterone/blood , Adolescent , Adult , Child , Humans , Male , Ontario , Saliva/chemistry , Young Adult
20.
Appl Physiol Nutr Metab ; 45(1): 91-100, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31652407

ABSTRACT

Exercise combined with protein and calcium has been shown to benefit bone turnover and bone metabolism. Greek yogurt (GY) contains important nutrients that support bone but has yet to be studied with exercise for this purpose. Thirty untrained, university-aged, males were randomized to 2 groups (n = 15/group): GY (20 g protein, 208 mg calcium/dose) or placebo pudding (PP; 0 g protein, 0 g calcium/dose) consumed 3×/day on training days and 2×/day on nontraining days. Both groups underwent a resistance/plyometric training program for 12 weeks. Blood was obtained at weeks 0, 1, and 12 to measure procollagen-type-I-N-terminal-propeptide (P1NP) and C-terminal-telopeptide (CTX). After outlier treatment, P1NP increased more over time in GY versus PP (p = 0.002; interaction). Both groups decreased CTX over time (p = 0.046; time effect). Following 1 week of training, there was a trend towards a significant increase in CTX in PP with no change in GY (p = 0.062; interaction). P1NP changed more in GY than PP (baseline to week 12; p = 0.029) as did the P1NP/CTX ratio (p = 0.015) indicating a greater increase in formation with GY. Thus, GY added to a high-load, high-impact exercise program positively shifted bone turnover towards increased formation while attenuating resorption. GY could be a plausible postexercise food to support bone health in young adult males. Novelty Greek yogurt, with exercise, increased bone formation in young adult males over 12 weeks. After 1 week of an osteogenic exercise program, Greek yogurt tended to blunt a rise in bone resorption seen with the placebo. Greek yogurt is a plausible postexercise food that supports bone.


Subject(s)
Bone Remodeling/physiology , Diet , Exercise/physiology , Yogurt , Adolescent , Adult , Biomarkers/blood , Exercise Therapy , Humans , Male , Peptide Fragments/blood , Procollagen/blood , Resistance Training , Young Adult
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